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Sample records for tropical southwestern atlantic

  1. Seaweed beds support more juvenile reef fish than seagrass beds in a south-western Atlantic tropical seascape

    Science.gov (United States)

    Eggertsen, L.; Ferreira, C. E. L.; Fontoura, L.; Kautsky, N.; Gullström, M.; Berkström, C.

    2017-09-01

    Seascape connectivity is regarded essential for healthy reef fish communities in tropical shallow systems. A number of reef fish species use separate adult and nursery habitats, and hence contribute to nutrient and energy transfer between habitats. Seagrass beds and mangroves often constitute important nursery habitats, with high structural complexity and protection from predation. Here, we investigated if reef fish assemblages in the tropical south-western Atlantic demonstrate ontogenetic habitat connectivity and identify possible nurseries on three reef systems along the eastern Brazilian coast. Fish were surveyed in fore reef, back reef, Halodule wrightii seagrass beds and seaweed beds. Seagrass beds contained lower abundances and species richness of fish than expected, while Sargassum-dominated seaweed beds contained significantly more juveniles than all other habitats (average juvenile fish densities: 32.6 per 40 m2 in Sargassum beds, 11.2 per 40 m2 in back reef, 10.1 per 40 m2 in fore reef, and 5.04 per 40 m2 in seagrass beds), including several species that are found in the reef habitats as adults. Species that in other regions worldwide (e.g. the Caribbean) utilise seagrass beds as nursery habitats were here instead observed in Sargassum beds or back reef habitats. Coral cover was not correlated to adult fish distribution patterns; instead, type of turf was an important variable. Connectivity, and thus pathways of nutrient transfer, seems to function differently in east Brazil compared to many tropical regions. Sargassum-dominated beds might be more important as nurseries for a larger number of fish species than seagrass beds. Due to the low abundance of structurally complex seagrass beds we suggest that seaweed beds might influence adult reef fish abundances, being essential for several keystone species of reef fish in the tropical south-western Atlantic.

  2. Salinity-induced mixed and barrier layers in the southwestern tropical Atlantic Ocean off the northeast of Brazil

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    M. Araujo

    2011-01-01

    Full Text Available High-resolution hydrographic observations of temperature and salinity are used to analyze the formation and distribution of isothermal depth (ZT, mixed depth (ZM and barrier layer thickness (BLT in a section of the southwestern Atlantic (0°30´ N–14°00´ S; 31°24´–41°48´ W, adjacent to the northeastern Brazilian coast. Analyzed data consists of 279 CTD casts acquired during two cruises under the Brazilian REVIZEE Program. One occurred in late austral winter (August–October 1995 and another in austral summer (January–April 1997. Oceanic observations are compared to numerical modeling results obtained from the French Mercator-Coriolis Program. Results indicate that the intrusion of subtropical Salinity Maximum Waters (SMW is the major process contributing to the seasonal barrier layer formation. These waters are brought by the South Equatorial Current (SEC, from the subtropical region, into the western tropical Atlantic boundary. During late austral winter southeastern trade winds are more intense and ITCZ precipitations induce lower surface salinity values near the equator. During this period a 5–90 m thick BLT (median = 15 m is observed and BLT > 30 m is restricted to latitudes higher than 8° S, where the intrusion of salty waters between 8°–12.3° S creates shallow mixed layers over deep (ZT ≥ 90 m isothermal layers. During austral summer, shallow isothermal and mixed layers prevail, when northeasterly winds are predominant and evaporation overcomes precipitation, causing saltier waters at the surface/subsurface layers. During that period observed BLT varies from 5 to 70 m and presents thicker median value of 35 m, when comparing to the winter. Furthermore, BLT ≥ 30 m is observed not only in the southernmost part of the study area, as verified during late winter, but in the latitude range 2°–14° S, where near-surface salty waters are transported westward by the

  3. GARP Atlantic Tropical Experiment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The GARP Atlantic Tropical Experiment (GATE) was the first major international experiment of the Global Atmospheric Research Program (GARP). It was conducted over...

  4. Temporal variability in phytoplankton pigments, picoplankton and coccolithophores along a transect through the North Atlantic and tropical southwestern Pacific

    Science.gov (United States)

    Dandonneau, Yves; Montel, Yves; Blanchot, Jean; Giraudeau, Jacques; Neveux, Jacques

    2006-04-01

    Biogeochemical processes in the sea are triggered in various ways by chlorophyll-containing phytoplankton groups. While the variability of chlorophyll concentration at sea has been observed from satellites for several years, these groups are known only from cruises which are limited in space and time. The Geochemistry, Phytoplankton and Color of the Ocean programme (GeP&CO) was set up to describe and understand the variability of phytoplankton composition on large spatial scales under a multi-year sampling strategy. It was based on sea-surface sampling along the route of the merchant ship Contship London which travelled four times a year from Le Havre (France) to Nouméa (New Caledonia) via New York, Panama and Auckland. Observations included the measurement of photosynthetic pigments, counts of picoplanktonic cells by flow cytometry (Prochlorococcus, Synechococcus, and picoeucaryotes) and counting and identification of coccolithophores. The results confirmed that tropical areas have low seasonal variability and are characterized by relatively high divinyl-chlorophyll a and zeaxanthin concentration and that the variability is strongest at high latitudes where the phytoplankton biomass and population structure are found to have large seasonal cycles. Thus, the spring bloom in the North Atlantic and an austral winter bloom north of New Zealand are marked by chlorophyll concentrations which are often higher than 0.5 μg l -1 and by high concentration of fucoxanthin (a pigment used as an indicator for diatoms), while summer populations are dominated by Prochlorococcus sp. and have low chlorophyll concentrations. Apart from this yearly bloom at temperate latitudes, fucoxanthin is scarce, except in the equatorial upwelling zone in the eastern Pacific Ocean, where it is found in moderate amounts. In this region, relatively high chlorophyll concentrations extend generally as far as 14°S and do not respond to the seasonal strengthening of the equatorial upwelling during

  5. Effects of tourist visitation and supplementary feeding on fish assemblage composition on a tropical reef in the Southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    Martina Di Iulio Ilarri

    Full Text Available The effects of tourist visitation and food provisioning on fish assemblages were assessed by visual censuses (stationary technique carried out in a tropical reef in Northeastern Brazil. Comparisons of species abundance, richness, equitability, and trophic structure in the presence (PT and absence (AT of tourists suggest that tourist visitation and supplementary food influenced the structure of the fish assemblage, as follows: (a diversity, equitability and species richness were significantly higher on the AT period, while the abundance of a particular species was significantly higher during PT; (b trophic structure differed between the AT and PT periods, omnivores being more abundant during the latter period, while mobile invertivores, piscivores, roving herbivores and territorial herbivores were significantly more abundant on AT. Reef tourism is increasingly being regarded as an alternative to generate income for human coastal communities in the tropics. Therefore, closer examination of the consequences of the various components of this activity to reef system is a necessary step to assist conservation and management initiatives.

  6. Two Distinct Roles of Atlantic SSTs in ENSO Variability: North Tropical Atlantic SST and Atlantic Nino

    Science.gov (United States)

    Ham, Yoo-Geun; Kug, Jong-Seong; Park, Jong-Yeon

    2013-01-01

    Two distinct roles of the Atlantic sea surface temperatures (SSTs), namely, the North Tropical Atlantic (NTA) SST and the Atlantic Nino, on the El Nino-Southern Oscillation (ENSO) variability are investigated using the observational data from 1980 to 2010 and coupled model experiments. It appears that the NTA SST and the Atlantic Nino can be used as two independent predictors for predicting the development of ENSO events in the following season. Furthermore, they are likely to be linked to different types of El Nino events. Specifically, the NTA SST cooling during February, March, and April contributes to the central Pacific warming at the subsequent winter season, while the negative Atlantic Nino event during June, July, and August contributes to enhancing the eastern Pacific warming. The coupled model experiments support these results. With the aid of a lagged inverse relationship, the statistical forecast using two Atlantic indices can successfully predict various ENSO indices.

  7. Satellite captures trichodesmium blooms in the southwestern tropical Pacific

    Science.gov (United States)

    Dupouy, Cécile; Neveux, Jacques; Subramaniam, Ajit; Mulholland, Margaret R.; Montoya, Joseph P.; Campbell, Lisa; Carpenter, Edward J.; Capone, Douglas G.

    Obtaining a true estimate of nitrogen fixation by cyanobacteria in the oceans, mainly Trichodesmium, is an important step toward understanding the entire nitrogen cycle in the tropical ocean. This strictly anaerobic process, which has a high Fe requirement, could regulate atmospheric CO2 over geological time. For example, during interglacial periods, N2 fixation would be too low (low Fe) to balance denitrification and the ocean would lose its fixed nitrogen [Falkowski, 1997]. Has the level of marine nitrogen fixation been underestimated until now? High N2 fixation rates measured on Trichodesmium spp. communities have led to an upward revision of this marine flux [Capone et al, 1997]. Recent modeling studies and observations predict that N2 fixation could regulate the long-term N:P equilibrium in the oceans and balance denitrification [Tyrell, 1999; J L. Sarmiento and N. Gruber, manuscript in preparation, 1999].The major nitrogen fixer, Trichodesmium spp., which are filamentous, nonheterocystous N2-fixing cyanobacteria, has a nearly ubiquitous distribution in the euphotic zone of tropical and subtropical seas and could play a major role in bringing new N to these oligotrophic systems. Satellite images from Sea-viewing Wide Field-of-view Sensor (SeaWiFs), the recently launched ocean color sensor, and data from a recent cruise, provide further evidence of the importance of Trichodesmium in the southwestern tropical Pacific Ocean.

  8. Acoustic habitat of an oceanic archipelago in the Southwestern Atlantic

    Science.gov (United States)

    Bittencourt, Lis; Barbosa, Mariana; Secchi, Eduardo; Lailson-Brito, José; Azevedo, Alexandre

    2016-09-01

    Underwater soundscapes can be highly variable, and in natural conditions are often dominated by biological signals and physical features of the environment. Few studies, however, focused on oceanic islands soundscapes. Islands in the middle of ocean basins can provide a good example of how untouched marine soundscapes are. Autonomous acoustic recordings were carried out in two different seasons in Trindade-Martin Vaz Archipelago, Southwestern Atlantic, providing nearly continuous data for both periods. Sound levels varied daily and between seasons. During summer, higher frequencies were noisier than lower frequencies, with snapping shrimp being the dominating sound source. During winter, lower frequencies were noisier than higher frequencies due to humpback whale constant singing. Biological signal detection had a marked temporal pattern, playing an important role in the soundscape. Over 1000 humpback whale sounds were detected hourly during winter. Fish vocalizations were detected mostly during night time during both summer and winter. The results show an acoustic habitat dominated by biological sound sources and highlight the importance of the island to humpback whales in winter.

  9. Structure and Evolution of Thermohaline Staircases in Tropical North Atlantic

    Science.gov (United States)

    2007-12-01

    series of mixed layers separated by sharp interfaces. The discovery of these ‘ thermohaline staircases’ by Tait and Howe (1968) further stimulated...EVOLUTION OF THERMOHALINE STAIRCASES IN TROPICAL NORTH ATLANTIC by Steven Wall December 2007 Thesis Advisor: Timour Radko Second Reader...DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Structure and Evolution of Thermohaline Staircases in Tropical North Atlantic 6. AUTHOR(S

  10. Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic reefs.

    Science.gov (United States)

    Kikuchi, Ruy K P; Leão, Zelinda M A N; Oliveira, Marília D M

    2010-05-01

    Coral reefs along the Eastern Brazilian coast extend for a distance of 800 km from 12 degrees to 18 degrees S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90's in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA) protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA) Regional Node of the Global Coral Reef Monitoring Network (GCRMN) by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts) and similarity percentages (SIMPER) tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonics > 20cm per reef site) and of the coral recruits (colonies vital condition than the nearshore reefs and have a set of vitality indices more closely related to the Northwestern Atlantic reefs than the nearshore reef. These have been most severely impacted by the effects of direct human activities such as cuthrophic waters associated with sewage pollution, higher sedimentation rates and water turbidity, inadequate use of the reefs and over exploitation of their resources. The implementation of a more effective coral reef monitoring program in Bahia is mandatory, in order to improve the strategies for protection and management efforts of the reefs.

  11. Impact of the Atlantic on multidecadal tropical Pacific Variability

    Science.gov (United States)

    Levine, A. F. Z.; McPhaden, M. J.; Frierson, D. M.

    2017-12-01

    Multidecadal shifts in ENSO variability have been observed, but it is unclear if this variability is just a random variation in the ENSO cycle or whether it is forced by other modes of climate variability. Recent studies have suggested that the observed mean state differences in the tropical Pacific from the first decade and a half of the new millennium were driven by changes in the Atlantic SSTs. Here, we will show that the impact of Atlantic SST forcing on the tropical Pacific mean state are expressed as asymmetric changes to the annual cycle. The asymmetric changes in the tropical Pacific annual cycle creates a distinct signature in the relationship between the ENSO and the tropical Pacific annual cycle that we observe in the multidecadal ENSO variability in reanalysis and proxy records and that this variability follows the Atlantic Multidecadal Variability. We further find that there are concurrent changes in the location of the tropical Pacific ITCZ on multidecadal timescales. The shifts in location of the ITCZ in response to a warmer north Atlantic are consistent with the predictions of an ITCZ shift forced by an enhanced interhemispheric energy gradient. Targeted coupled model experiments are then used to confirm the impact of Atlantic Multidecadal Variability on the tropical Pacific multidecadal variability and explore the impact of SST changes across different regions of the Atlantic.

  12. Spatial and temporal distribution of North Atlantic tropical cyclones ...

    African Journals Online (AJOL)

    month of genesis and their lifecycles and to study the role of African Easterly Waves (AEWs) in North Atlantic cyclogenesis. Between 1980 and 2004, 269 tropical cyclones (TCs) were formed over the North Atlantic, 77% of which occurred during the August-October period and 95% of major hurricanes (TCs in which the ...

  13. Global Warming Attenuates the Tropical Atlantic-Pacific Teleconnection.

    Science.gov (United States)

    Jia, Fan; Wu, Lixin; Gan, Bolan; Cai, Wenju

    2016-02-03

    Changes in global sea surface temperature (SST) since the end of last century display a pattern of widespread warming intercepted by cooling in the eastern equatorial Pacific and western coasts of the American continent. Studies have suggested that the cooling in the eastern equatorial Pacific may be partly induced by warming in the North Atlantic. However, it remains unknown how stable this inter-tropical teleconnection will be under global warming. Here we show that the inter-tropical teleconnection from the tropical Atlantic to Pacific weakens substantially as the CO2 concentration increases. This reduced impact is related to the El Niño-like warming of the tropical Pacific mean state, which leads to limited seasonal migration of the Pacific inter-tropical convergence zone (ITCZ) and weakened ocean heat transport. A fast decay of the tropical Atlantic SST anomalies in a warmer climate also contributes to the weakened teleconnection. Our study suggests that as greenhouse warming continues, the trend in the tropical Pacific as well as the development of ENSO will be less frequently interrupted by the Atlantic because of this attenuation. The weakened teleconnection is also supported by CMIP5 models, although only a few of these models can capture this inter-tropical teleconnection.

  14. Global Warming Attenuates the Tropical Atlantic-Pacific Teleconnection

    Science.gov (United States)

    Jia, Fan; Wu, Lixin; Gan, Bolan; Cai, Wenju

    2016-01-01

    Changes in global sea surface temperature (SST) since the end of last century display a pattern of widespread warming intercepted by cooling in the eastern equatorial Pacific and western coasts of the American continent. Studies have suggested that the cooling in the eastern equatorial Pacific may be partly induced by warming in the North Atlantic. However, it remains unknown how stable this inter-tropical teleconnection will be under global warming. Here we show that the inter-tropical teleconnection from the tropical Atlantic to Pacific weakens substantially as the CO2 concentration increases. This reduced impact is related to the El Niño-like warming of the tropical Pacific mean state, which leads to limited seasonal migration of the Pacific inter-tropical convergence zone (ITCZ) and weakened ocean heat transport. A fast decay of the tropical Atlantic SST anomalies in a warmer climate also contributes to the weakened teleconnection. Our study suggests that as greenhouse warming continues, the trend in the tropical Pacific as well as the development of ENSO will be less frequently interrupted by the Atlantic because of this attenuation. The weakened teleconnection is also supported by CMIP5 models, although only a few of these models can capture this inter-tropical teleconnection. PMID:26838053

  15. Remotely forced variability in the tropical Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Huang, B. [Center for Ocean-Land-Atmosphere Studies, Institute of Global Environment and Society, 4041 Powder Mill Road, Calverton, Maryland 20705 (United States)

    2004-08-01

    An ensemble of eight hindcasts has been conducted using an ocean-atmosphere general circulation model fully coupled only within the Atlantic basin, with prescribed observational sea surface temperature (SST) for 1950-1998 in the global ocean outside the Atlantic basin. The purpose of these experiments is to understand the influence of the external SST anomalies on the interannual variability in the tropical Atlantic Ocean. Statistical methods, including empirical orthogonal function analysis with maximized signal-to-noise ratio, have been used to extract the remotely forced Atlantic signals from the ensemble of simulations. It is found that the leading external source on the interannual time scales is the El Nino/Southern Oscillation (ENSO) in the Pacific Ocean. The ENSO signal in the tropical Atlantic shows a distinct progression from season to season. During the boreal winter of a maturing El Nino event, the model shows a major warm center in the southern subtropical Atlantic together with warm anomalies in the northern subtropical Atlantic. The southern subtropical SST anomalies is caused by a weakening of the southeast trade winds, which are partly associated with the influence of an atmospheric wave train generated in the western Pacific Ocean and propagating into the Atlantic basin in the Southern Hemisphere during boreal fall. In the boreal spring, the northern tropical Atlantic Ocean is warmed up by a weakening of the northeast trade winds, which is also associated with a wave train generated in the central tropical Pacific during the winter season of an El Nino event. Apart from the atmospheric planetary waves, these SST anomalies are also related to the sea level pressure (SLP) increase in the eastern tropical Atlantic due to the global adjustment to the maturing El Nino in the tropical Pacific. The tropical SLP anomalies are further enhanced in boreal spring, which induce anomalous easterlies on and to the south of the equator and lead to a dynamical

  16. Rapid acidification of mode and intermediate waters in the southwestern Atlantic Ocean

    NARCIS (Netherlands)

    Salt, L.A.; Heuven, S.M.A.C.; Claus, M.E.; Jones, E.M.; de Baar, H.J.W.

    2015-01-01

    Observations along the southwestern Atlantic WOCE A17 line made during the Dutch GEOTRACES-NL programme (2010–2011) were compared with historical data from 1994 to quantify the changes in the anthropogenic component of the total pool of dissolved inorganic carbon (?Cant). Application of the extended

  17. Rapid acidification of mode and intermediate waters in the southwestern Atlantic Ocean

    NARCIS (Netherlands)

    Salt, L.A.; van Heuven, S.M.A.C.; Claus, M.E.; Jones, E.M.; de Baar, H.J.W.

    2015-01-01

    Observations along the southwestern Atlantic WOCE A17 line made during the Dutch GEOTRACESNL programme (2010-2011) were compared with historical data from 1994 to quantify the changes in the anthropogenic component of the total pool of dissolved inorganic carbon (Delta C-ant). Application of the

  18. Tropical Atlantic-Korea teleconnection pattern during boreal summer season

    Science.gov (United States)

    Ham, Yoo-Geun; Chikamoto, Yoshimitsu; Kug, Jong-Seong; Kimoto, Masahide; Mochizuki, Takashi

    2017-10-01

    The remote impact of tropical Atlantic sea surface temperature (SST) variability on Korean summer precipitation is examined based on observational data analysis along with the idealized and hindcast model experiments. Observations show a significant correlation (i.e. 0.64) between Korean precipitation anomalies (averaged over 120-130°E, 35-40°N) and the tropical Atlantic SST index (averaged over 60°W-20°E, 30°S-30°N) during the June-July-August (JJA) season for the 1979-2010 period. Our observational analysis and partial-data assimilation experiments using the coupled general circulation model demonstrate that tropical Atlantic SST warming induces the equatorial low-level easterly over the western Pacific through a reorganization of the global Walker Circulation, causing a decreased precipitation over the off-equatorial western Pacific. As a Gill-type response to this diabatic forcing, an anomalous low-level anticyclonic circulation appears over the Philippine Sea, which transports wet air from the tropics to East Asia through low-level southerly, resulting an enhanced precipitation in the Korean peninsula. Multi-model hindcast experiments also show that predictive skills of Korean summer precipitation are improved by utilizing predictions of tropical Atlantic SST anomalies as a predictor for Korean precipitation anomalies.

  19. Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic Reefs

    Directory of Open Access Journals (Sweden)

    Ruy K.P Kikuchi

    2010-05-01

    Full Text Available Coral reefs along the Eastern Brazilian coast extend for a distance of 800km from 12° to 18°S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90’s in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA Regional Node of the Global Coral Reef Monitoring Network (GCRMN by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts and similarity percentages (SIMPER tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonies >20cm per reef site and of the coral recruits (colonies<2cm per square meter, and the percentage of macroalgae indicate that the nearshore reefs, which are located less than 5km from the coast, are in poorer condition than the reefs located more than 5km off the coast. A higher density of coral colonies, lower macroalgal index, higher relative percent of turf algae and higher density of coral recruits in offshore reefs compared to the nearshore reefs are the conditions that contribute more than 80% to the dissimilarity between them. The offshore reefs are in better vital condition than the nearhore reefs and have a set of vitality indices more closely

  20. Remote impact of North Atlantic sea surface temperature on rainfall in southwestern China during boreal spring

    Science.gov (United States)

    Li, Gang; Chen, Jiepeng; Wang, Xin; Luo, Xia; Yang, Daoyong; Zhou, Wen; Tan, Yanke; Yan, Hongming

    2018-01-01

    As an important oceanic signal, the North Atlantic sea surface temperature (SST) affects not only the climate variability over East China and Northeast China but also can affect climate variability over southwestern China (SWC). Based on station rainfall data and reanalysis datasets, the present study investigates the relationship of North Atlantic SST with SWC rainfall during boreal spring for the period 1979-2016. The results show that there is a significant positive correlation between North Atlantic SST and SWC rainfall during boreal spring. The atmospheric circulation over southern Asia associated with North Atlantic SST is favorable for positive rainfall anomalies. Further analyses show that North Atlantic SST can induce a North Atlantic-western Russia-western Tibetan Plateau-SWC (NRTC) teleconnection wave train from upper level to low level. At low level, two anomalous anticyclones are found over the mid-high latitude of North Atlantic and the western Tibetan Plateau, and two anomalous cyclones are observed over the western Russia and Bay of Bengal (BOB), respectively. The NRTC teleconnection wave train plays a bridging role between the North Atlantic SST and SWC rainfall during boreal spring. Both the observational analysis and two numerical experiments suggest that the North Atlantic SST during boreal spring can induce an anomalous cyclone over BOB by the NRTC teleconnection pattern. The anomalous cyclone over BOB favors moisture transport to SWC, accompanying with significant anomalous ascending motion, and thus results in positive rainfall anomalies in SWC during boreal spring.

  1. Dissolved Carbon Dioxide in Tropical East Atlantic Surface Waters

    NARCIS (Netherlands)

    Bakker, D.C.E.; Baar, H.J.W. de; Jong, E. de

    1999-01-01

    Variability of dissolved inorganic carbon (DIC) and the fugacity of carbon dioxide (fCO2) is discussed for tropical East Atlantic surface waters in October–November 1993 and May–June 1994. High precipitation associated with the Intertropical Convergence Zone, river input and equatorial upwelling

  2. Stelletta hajdui, a new species from the southwestern Atlantic (Porifera, Choristida, Ancorinidae)

    NARCIS (Netherlands)

    Lerner, Cléa; Mothes, Beatriz

    1999-01-01

    A new species of Stelletta from the southwestern Atlantic, Stelletta hajdui sp.n. is described from the slope off Rio Grande do Sul State coast, Brazil (32°24'S, 50°15'W) (Fig.1). The material studied was dredged up at the depth of 200m by the R/V Atlântico Sul, during “Projeto Talude” run by

  3. Tropical Pacific influences on the North Atlantic Thermohaline Circulation

    Directory of Open Access Journals (Sweden)

    M. Latif

    2003-06-01

    Full Text Available Most global climate models simulate a weakening of the North Atlantic Thermohaline Circulation (THC in response to enhanced greenhouse warming. Both surface warming and freshening in high latitudes, the so-called sinking region, contribute to the weakening of the THC. Some models simulate even a complete breakdown of the THC at sufficiently strong forcing. Here results from a state-of-the-art global climate model are presented that does not simulate a weakening of the THC in response to greenhouse warming. Large-scale air-sea interactions in the tropics, similar to those operating during present-day El Niños, lead to anomalously high salinities in the tropical Atlantic. These are advected into the sinking region, thereby increasing the surface density and compensating the effects of the local warming and freshening. The results of the model study are corroborated by the analysis of observations.

  4. Tropical Forcing of the Summer East Atlantic Pattern

    Science.gov (United States)

    Wulff, C. Ole; Greatbatch, Richard J.; Domeisen, Daniela I. V.; Gollan, Gereon; Hansen, Felicitas

    2017-11-01

    The Summer East Atlantic (SEA) mode is the second dominant mode of summer low-frequency variability in the Euro-Atlantic region. Using reanalysis data, we show that SEA-related circulation anomalies significantly influence temperatures and precipitation over Europe. We present evidence that part of the interannual SEA variability is forced by diabatic heating anomalies of opposing signs in the tropical Pacific and Caribbean that induce an extratropical Rossby wave train. This precipitation dipole is related to SST anomalies characteristic of the developing El Niño-Southern Oscillation phases. Seasonal hindcast experiments forced with observed sea surface temperatures (SSTs) exhibit skill at capturing the interannual SEA variability corroborating the proposed mechanism and highlighting the possibility for improved prediction of boreal summer variability. Our results indicate that tropical forcing of the SEA likely played a role in the dynamics of the 2015 European heat wave.

  5. Persistent influence of tropical North Atlantic wintertime sea surface temperature on the subsequent Atlantic hurricane season

    Science.gov (United States)

    Wang, Xidong; Liu, Hailong; Foltz, Gregory R.

    2017-08-01

    This study explores the seasonally lagged impact of wintertime sea surface temperature (SST) in the Atlantic main development region (MDR) on the subsequent Atlantic hurricane season. It is found that wintertime SST anomalies in the MDR can persist into the summer, explaining 42% of the variance in the subsequent hurricane season's SST during 1951-2010. An anomalously warm wintertime in the MDR is usually followed by an anomalously active hurricane season. Analysis shows an important constraint on the seasonal evolution of the MDR SST by the water vapor feedback process, in addition to the well-known wind-evaporation-SST and cloud-SST feedback mechanisms over the tropical North Atlantic. The water vapor feedback influences the seasonal evolution of MDR SST by modulating seasonal variations of downward longwave radiation. This wintertime thermal control of hurricane activity has significant implications for seasonal predictions and long-term projections of hurricane activity over the North Atlantic.

  6. Tropical Atlantic Impacts on the Decadal Climate Variability of the Tropical Ocean and Atmosphere.

    Science.gov (United States)

    Li, X.; Xie, S. P.; Gille, S. T.; Yoo, C.

    2015-12-01

    Previous studies revealed atmospheric bridges between the tropical Pacific, Atlantic, and Indian Ocean. In particular, several recent works indicate that the Atlantic sea surface temperature (SST) may contribute to the climate variability over the equatorial Pacific. Inspired by these studies, our work aims at investigating the impact of the tropical Atlantic on the entire tropical climate system, and uncovering the physical dynamics under these tropical teleconnections. We first performed a 'pacemaker' simulation by restoring the satellite era tropical Atlantic SST changes in a fully coupled model - the CESM1. Results reveal that the Atlantic warming heats the Indo-Western Pacific and cools the Eastern Pacific, enhances the Walker circulation and drives the subsurface Pacific to a La Niña mode, contributing to 60-70% of the above tropical changes in the past 30 years. The same pan-tropical teleconnections have been validated by the statistics of observations and 106 CMIP5 control simulations. We then used a hierarchy of atmospheric and oceanic models with different complexities, to single out the roles of atmospheric dynamics, atmosphere-ocean fluxes, and oceanic dynamics in these teleconnections. With these simulations we established a two-step mechanism as shown in the schematic figure: 1) Atlantic warming generates an atmospheric deep convection and induces easterly wind anomalies over the Indo-Western Pacific in the form of Kelvin waves, and westerly wind anomalies over the eastern equatorial Pacific as Rossby waves, in line with Gill's solution. This circulation changes warms the Indo-Western Pacific and cools the Eastern Pacific with the wind-evaporation-SST effect, forming a temperature gradient over the Indo-Pacific basins. 2) The temperature gradient further generates a secondary atmospheric deep convection, which reinforces the easterly wind anomalies over the equatorial Pacific and enhances the Walker circulation, triggering the Pacific to a La Ni

  7. Variability in Global-Scale Circulations and Their Impacts on Atlantic Tropical Cyclone Activity

    National Research Council Canada - National Science Library

    Rosencrans, Matthew J

    2006-01-01

    ... favorable or unfavorable for tropical cyclone formation. Favorable impacts on tropical Atlantic circulation characteristics are defined by an increase in low-level relative vorticity, a decrease in westerly vertical wind shear, and increased convection...

  8. Use efficiency of tropical rainforest soils of southwestern Nigeria as ...

    African Journals Online (AJOL)

    Conventional management methods degraded soil quality indicators while farmers' traditional practices minimize soil quality degradation. It is recommended that farmers' practices that will protect sensitive soil quality indicators are panacea to soil quality management in forest ecology of the tropics. Keywords: Soil quality ...

  9. Teleconnections of the tropical Atlantic to the tropical Indian and Pacific Oceans. A review of recent findings

    Energy Technology Data Exchange (ETDEWEB)

    Wang Chunzai [NOAA Atlantic Oceanographic and Meteorological Lab., Miami, FL (United States); Kucharski, Fred; Barimalala, Rondrotiana [The Abdus Salam International Centre for Theoretical Physics, Earth System Physics, Section Trieste (Italy); Bracco, Annalisa [School of Earth and Atmospheric Sciences Georgia, Inst. of Tech., Atlanta, GA (United States)

    2009-08-15

    Recent studies found that tropical Atlantic variability may affect the climate in both the tropical Pacific and Indian Ocean basins, possibly modulating the Indian summer monsoon and Pacific ENSO events. A warm tropical Atlantic Ocean forces a Gill-Matsuno-type quadrupole response with a low-level anticyclone located over India that weakens the Indian monsoon circulation, and vice versa for a cold tropical Atlantic Ocean. The tropical Atlantic Ocean can also induce changes in the Indian Ocean sea surface temperatures (SSTs). especially along the coast of Africa and in the western side of the Indian basin. Additionally, it can influence the tropical Pacific Ocean via an atmospheric teleconnection that is associated with the Atlantic Walker circulation. Although the Pacific El Nino does not contemporaneously correlate with the Atlantic Nino, anomalous warming or cooling of the two equatorial oceans can form an inter-basin SST gradient that induces surface zonal wind anomalies over equatorial South America and other regions in both ocean basins. The zonal wind anomalies act as a bridge linking the two ocean basins, and in turn reinforce the inter-basin SST gradient through the atmospheric Walker circulation and oceanic processes. Thus, a positive feedback seems to exist for climate variability of the tropical Pacific-Atlantic Oceans and atmospheric system, in which the inter-basin SST gradient is coupled to the overlying atmospheric wind. (orig.)

  10. Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic Reefs

    Directory of Open Access Journals (Sweden)

    Ruy K.P Kikuchi

    2010-05-01

    Full Text Available Coral reefs along the Eastern Brazilian coast extend for a distance of 800km from 12° to 18°S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90’s in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA Regional Node of the Global Coral Reef Monitoring Network (GCRMN by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts and similarity percentages (SIMPER tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonies >20cm per reef site and of the coral recruits (coloniesDesde el año 2000 se inició un programa de monitoreo utilizando el protocolo AGRRA en el Parque Nacional Marino de Abrolhos en el marco de la creación del Nodo STA de la GCRMN. Entre 2000 y 2005 se realizaron varias evaluaciones en 26 arrecifes. Los patrones espaciales y temporales de la vitalidad de los arrecifes fueron estudiados mediante análisis de ordenación (MDS, similaridad (ANOSIM y porcentajes de similaridad (SIMPER. La cobertura de coral vivo, la densidad de colonias grandes (>20cm y de reclutas (<2cm y la cobertura de macroalgas indicaron que los arrecifes ubicados a más de 5km de la

  11. Medicinal plants popularly used in the Brazilian Tropical Atlantic Forest.

    Science.gov (United States)

    Di Stasi, L C; Oliveira, G P; Carvalhaes, M A; Queiroz, M; Tien, O S; Kakinami, S H; Reis, M S

    2002-02-01

    A survey of medicinal plants used by rural and urban inhabitants of the three cities of the Tropical Atlantic Forest, Region of Vale do Ribeira, State of São Paulo, Brazil was performed by means of 200 interviews with medicinal plant users and extractors and, traditional healers. One hundred fourteen herbal remedies were recorded and the following information reported: Latin, vernacular and English names, plant part used, forms of preparation and application of the herbal remedies, medicinal or food uses, areas of plant collection, economic importance (when available) and other data.

  12. Invasive species in the Northeastern and Southwestern Atlantic Ocean: A review.

    Science.gov (United States)

    Castro, Maria Cecilia T de; Fileman, Timothy W; Hall-Spencer, Jason M

    2017-03-15

    The spread of non-native species has been a subject of increasing concern since the 1980s when human-mediated transportation, mainly related to ships' ballast water, was recognized as a major vector for species transportation and spread, although records of non-native species go back as far as 16th Century. Ever increasing world trade and the resulting rise in shipping have highlighted the issue, demanding a response from the international community to the threat of non-native marine species. In the present study, we searched for available literature and databases on shipping and invasive species in the North-eastern (NE) and South-western (SW) Atlantic Ocean and assess the risk represented by the shipping trade between these two regions. There are reports of 44 species associated with high impacts for the NE Atlantic and 15 for the SW Atlantic, although this may be an underestimate. Vectors most cited are ballast water and biofouling for both regions while aquaculture has also been a very significant pathway of introduction and spread of invasive species in the NE Atlantic. Although the two regions have significant shipping traffic, no exchange of invasive species could be directly associated to the shipping between the two regions. However, it seems prudent to bring the exchange of ballast water between the two regions under control as soon as possible. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Microbial diversity from chlorophyll maximum, oxygen minimum and bottom zones in the southwestern Atlantic Ocean

    Science.gov (United States)

    Medina-Silva, Renata; de Oliveira, Rafael R.; Pivel, Maria A. G.; Borges, Luiz G. A.; Simão, Taiz L. L.; Pereira, Leandro M.; Trindade, Fernanda J.; Augustin, Adolpho H.; Valdez, Fernanda P.; Eizirik, Eduardo; Utz, Laura R. P.; Groposo, Claudia; Miller, Dennis J.; Viana, Adriano R.; Ketzer, João M. M.; Giongo, Adriana

    2018-02-01

    Conspicuous physicochemical vertical stratification in the deep sea is one of the main forces driving microbial diversity in the oceans. Oxygen and sunlight availability are key factors promoting microbial diversity throughout the water column. Ocean currents also play a major role in the physicochemical stratification, carrying oxygen down to deeper zones as well as moving deeper water masses up towards shallower depths. Water samples within a 50-km radius in a pockmark location of the southwestern Atlantic Ocean were collected and the prokaryotic communities from different water depths - chlorophyll maximum, oxygen minimum and deep-sea bottom (down to 1355 m) - were described. At phylum level, Proteobacteria were the most frequent in all water depths, Cyanobacteria were statistically more frequent in chlorophyll maximum zone, while Thaumarchaeota were significantly more abundant in both oxygen minimum and bottom waters. The most frequent microorganism in the chlorophyll maximum and oxygen minimum zones was a Pelagibacteraceae operational taxonomic unit (OTU). At the bottom, the most abundant genus was the archaeon Nitrosopumilus. Beta diversity analysis of the 16S rRNA gene sequencing data uncovered in this study shows high spatial heterogeneity among water zones communities. Our data brings important contribution for the characterisation of oceanic microbial diversity, as it consists of the first description of prokaryotic communities occurring in different oceanic water zones in the southwestern Atlantic Ocean.

  14. Spatial variation in density and size structure indicate habitat selection throughout life stages of two Southwestern Atlantic snappers.

    Science.gov (United States)

    Aschenbrenner, Alexandre; Hackradt, Carlos Werner; Ferreira, Beatrice Padovani

    2016-02-01

    The early life history of Lutjanus alexandrei and Lutjanus jocu in Southwestern Atlantic is still largely unknown. Habitat use of different life stages (i.e. size categories and densities) of the Brazilian snapper (L. alexandrei) and dog snapper (L. jocu) was examined in a tropical portion of NE coast of Brazil. Visual surveys were conducted in different shallow habitats (mangroves and reefs). Both snapper species showed higher densities in early life stages in mangrove habitat, with a clear increase in fish size from mangrove to adjacent reefs. Post-settler individuals were exclusively found in mangroves for both species. Juveniles of L. alexandrei were also registered only in mangroves, while sub-adult individuals were associated with both mangrove and reef habitats. Mature individuals of L. alexandrei were only observed in reef habitats. Juvenile and sub-adult individuals of the dog snapper were both associated with mangrove and reef habitats, with high densities registered in mangroves. Mature individuals of L. jocu were not registered in the study area. This pattern suggests preference for mangrove habitat in early life stages for both species. Ontogenetic movement between habitats was also recorded. This pattern denotes habitat selection across different life cycle of both species. Such information highlights the importance of directing management and conservation efforts to these habitats to secure the continuity of contribution to adult populations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Isopycnal diffusivity in the tropical North Atlantic oxygen minimum zone

    Science.gov (United States)

    Köllner, Manuela; Visbeck, Martin; Tanhua, Toste; Fischer, Tim

    2017-04-01

    Isopycnal diffusivity plays an important role in the ventilation of the Eastern Tropical North Atlantic (ETNA) Oxygen Minimum Zone (OMZ). Lateral tracer transport is described by isopycnal diffusivity and mean advection of the tracer (e.g. oxygen), together they account for up to 70% of the oxygen supply for the OMZ. One of the big challenges is to separate diffusivity from advection. Isopycnal diffusivity was estimated to be Ky=(500 ± 200) m2 s-1 and Kx=(1200 ± 600) m2 s-1 by Banyte et. al (2013) from a Tracer Release Experiment (TRE). Hahn et al. (2014) estimated a meridional eddy diffusivity of 1350 m2 s-1 at 100 m depth decaying to less than 300 m2 s-1 below 800 m depth from repeated ship sections of CTD and ADCP data in addition with hydrographic mooring data. Uncertainties of the estimated diffusivities were still large, thus the Oxygen Supply Tracer Release Experiment (OSTRE) was set up to estimate isopycnal diffusivity in the OMZ using a newly developed sampling strategy of a control volume. The tracer was released in 2012 in the core of the OMZ at approximately 410 m depth and mapped after 6, 15 and 29 months in a regular grid. In addition to the calculation of tracer column integrals from vertical tracer profiles a new sampling method was invented and tested during two of the mapping cruises. The mean eddy diffusivity during OSTRE was found to be about (300 ± 130) m2 s-1. Additionally, the tracer has been advected further to the east and west by zonal jets. We compare different analysis methods to estimate isopycnal diffusivity from tracer spreading and show the advantage of the control volume surveys and control box approach. From the control box approach we are estimating the strength of the zonal jets within the OMZ core integrated over the TRE time period. References: Banyte, D., Visbeck, M., Tanhua, T., Fischer, T., Krahmann, G.,Karstensen, J., 2013. Lateral Diffusivity from Tracer Release Experiments in the Tropical North Atlantic Thermocline

  16. Statistical Aspects of Tropical Cyclone Activity in the North Atlantic Basin, 1945-2010

    Science.gov (United States)

    Wilson, Robert M.

    2012-01-01

    Examined are statistical aspects of the 715 tropical cyclones that formed in the North Atlantic basin during the interval 1945-2010. These 715 tropical cyclones include 306 storms that attained only tropical storm strength, 409 hurricanes, 179 major or intense hurricanes, and 108 storms that struck the US coastline as hurricanes. Comparisons made using 10-year moving average (10-yma) values between tropical cyclone parametric values and surface air and ENSO-related parametric values indicate strong correlations to exist, in particular, against the Armagh Observatory (Northern Ireland) surface air temperature, the Atlantic Multi-decadal Oscillation (AMO) index, the Atlantic Meridional Mode (AMM) index, and the North Atlantic Oscillation (NAO) index, in addition to the Oceanic Ni o index (ONI) and Quasi-Biennial Oscillation (QBO) indices. Also examined are the decadal variations of the tropical cyclone parametric values and a look ahead towards the 2012 hurricane season and beyond.

  17. Evidences linking ENSO and coral growth in the Southwestern-South Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Evangelista, H. [LARAMG, Laboratorio de Radioecologia e Mudancas Globais/DBB/UERJ. Pav. HLC, Subsolo, Maracana, RJ (Brazil); Godiva, D. [LARAMG, Laboratorio de Radioecologia e Mudancas Globais/DBB/UERJ. Pav. HLC, Subsolo, Maracana, RJ (Brazil); Universidade Federal Fluminense, Outeiro Sao Joao Batista, s/n, Centro, Departamento de Geoquimica Ambiental, Niteroi, RJ (Brazil); Sifeddine, A. [IRD, Institut de Recherche Pour le Developpement, UR055 Paleotropique, Bondy (France); Universidade Federal Fluminense, Outeiro Sao Joao Batista, s/n, Centro, Departamento de Geoquimica Ambiental, Niteroi, RJ (Brazil); Leao, Z.M.A.N.; Kikuchi, R.K.P. [UFBA/Instituto de Geociencias. Rua Barao de Geremoabo, s/n, Federacao, Salvador, BA (Brazil); Rigozo, N.R. [LARAMG, Laboratorio de Radioecologia e Mudancas Globais/DBB/UERJ. Pav. HLC, Subsolo, Maracana, RJ (Brazil); FAETEC, Faculdade de Educacao e Tecnologia Thereza Porto Marques, Jacarei, SP (Brazil); Segal, B. [UFRJ/Museu Nacional/Setor de Celenterologia/Departamento de Invertebrados, Quinta da Boa Vista s/n, Sao Cristovao, RJ (Brazil); Ambrizzi, T. [USP/Department of Atmospheric Sciences, Sao Paulo, SP (Brazil); Kampel, M. [INPE/Divisao de Sensoriamento Remoto, Sao Paulo, SP (Brazil); Cornec, F. le [Universidade Federal Fluminense, Outeiro Sao Joao Batista, s/n, Centro, Departamento de Geoquimica Ambiental, Niteroi, RJ (Brazil)

    2007-12-15

    Physical and biological changes in the marine environment, induced by oceanic-atmospheric processes, can be imprinted in massive coral skeletons. Herein, we present an evidence of potential El Nino impacts at the Southwestern South Atlantic Ocean (SWSA) inferred from the sclerochronology of the reef coral Favia leptophylla. The application of spectral analysis (wavelet decomposition and the iterative regression) to coral growth length and to meteorological-oceanographic parameters (air temperature, sea surface temperature and precipitation) as well as to Southern Oscillation Index (SOI) and solar irradiation indicated a major significant inverse relationship between SOI and coral growth length at the 4-8 years frequency band. We propose here that coral growth length from the SWSA could be affected by El Nino Southern Oscillation (ENSO) events through an ''atmospheric bridge'', in contrast to its direct effect at the Pacific Ocean, related to the increase in sea surface temperature. (orig.)

  18. A new species of dwarf sea bass, genus Serranus (Serranidae: Actinopterygii, from the southwestern Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Alfredo Carvalho Filho

    Full Text Available Serranus aliceae n. sp. is described from Rio de Janeiro and Espírito Santo States, southeastern Brazilian coast. The species is readily distinguished from its congeners by the following combination of characters: scales around the caudal peduncle 20 or 21; total gill rakers on first branchial arch 23-29; cheek-scales rows 5 or 6; and by the coloration of live specimens, which are reddish with a broad, conspicuous, white stripe from post-orbital region to the caudal-fin base and a white abdomen. The new species apparently inhabits the deeper (30 or more meters portions of reef environments along the subtropical Brazilian coast, and is possibly associated with upwelling cold-water masses. The species was observed hovering above rocky bottoms, feeding on micro-crustaceans, squid larvae, and zooplankton. This new species increases to eight the number of valid Serranus species recorded in the southwestern Atlantic.

  19. Absonifibula estuarina sp. n. (Monogenea: Diclidophoridae parasite of juvenile Cynoscion guatucupa (Osteichthyes from southwestern Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Cláudia Portes Santos

    2009-11-01

    Full Text Available Absonifibula estuarina sp. n. (Diclidophoridae, Absonifibulinae, is described from the gills of juvenile striped weakfish, Cynoscion guatucupa (Cuvier, from the southwestern Atlantic, Argentinean coast. This marine fish migrates to estuarine areas to spawn where exclusively juveniles are found parasitized; adult fish in marine water were never found to be parasitized by this monogenean. A. estuarina sp. n. is characterized mainly by the pedunculate clamps dissimilar in size, the shape of anterior jaw with sclerite 'a' attached to a sub-trapezoidal lamellate extension and fused to sclerites 'c' and 'd'. It differs from Absonifibula bychowskyi Lawler & Overstreet, 1976, the only known species of the genus, in the shape and arrangement of the genital corona, which is armed with six similar hooks disposed in circle and the sub-trapezoidal shape of lamellate extension ('b'. The restriction to juvenile sciaenids is a shared feature among the Absonifibulinae indicating an estuary-dependent life cycle.

  20. Statistical Aspects of the North Atlantic Basin Tropical Cyclones: Trends, Natural Variability, and Global Warming

    Science.gov (United States)

    Wilson, Robert M.

    2007-01-01

    Statistical aspects of the North Atlantic basin tropical cyclones for the interval 1945- 2005 are examined, including the variation of the yearly frequency of occurrence for various subgroups of storms (all tropical cyclones, hurricanes, major hurricanes, U.S. landfalling hurricanes, and category 4/5 hurricanes); the yearly variation of the mean latitude and longitude (genesis location) of all tropical cyclones and hurricanes; and the yearly variation of the mean peak wind speeds, lowest pressures, and durations for all tropical cyclones, hurricanes, and major hurricanes. Also examined is the relationship between inferred trends found in the North Atlantic basin tropical cyclonic activity and natural variability and global warming, the latter described using surface air temperatures from the Armagh Observatory Armagh, Northern Ireland. Lastly, a simple statistical technique is employed to ascertain the expected level of North Atlantic basin tropical cyclonic activity for the upcoming 2007 season.

  1. Do the Atlantic climate modes impact the ventilation of the eastern tropical North Atlantic oxygen minimum zones?

    Science.gov (United States)

    Burmeister, Kristin; Lübbecke, Joke F.

    2017-04-01

    Oxygen minimum zones (OMZs) exist in the upwelling regions of the eastern tropical Atlantic and Pacific at intermediate depth. They are a consequence of high biological productivity in combination with weak ventilation. The flow fields in the tropical Atlantic is characterized by Latitudinally Alternating Zonal Jets (LAZJs) with a large vertical scale. It has been suggested that LAZJs play an important role for the ventilation of the OMZ as eastward currents advect oxygen-rich waters from the western boundary towards the OMZ. In the Eastern Tropical North Atlantic (ETNA), the eastward flowing North Equatorial Undercurrent and North Equatorial Countercurrent (NECC) provide the main oxygen supply into the OMZ. Variability in the strength and location of the LAZJs is associated with oxygen variability in the ETNA OMZ. We here want to address the question whether the variability in the zonal current field can be partly attributed to the large-scale climate modes of the tropical Atlantic, namely the Atlantic zonal and meridional mode. An influence of these modes on the NECC has been found in previous studies. For the analysis we are using the output of a global ocean circulation model, in which a 1/10° nest covering the tropical Atlantic is embedded into a global 1/2° model, as well as reanalysis products and satellite data. The zonal current field and oxygen distribution from the high resolution model is compared to observational data. The location and intensity of the current bands during positive and negative phases of the Atlantic climate modes are compared by focusing on individual events and via composite analysis. Based on the results, the potential impact of the Atlantic climate modes on the ventilation of the ETNA OMZ is discussed.

  2. Property Changes of Abyssal Waters in the Western Tropical Atlantic

    Science.gov (United States)

    Herrford, Josefine; Brandt, Peter; Zenk, Walter

    2017-04-01

    Flowing northward towards the equator, Antarctic Bottom Water (AABW) encounters the lighter overlying North Atlantic Deep Water (NADW), both water masses creating an abyssal stratification and gradually mixing across their interface. Changes in the associated water mass formation and/or along-path transformation, observable in the evolution of water mass volume and characteristics, might impact the deep oceans uptake of anthropogenic CO2 or its contribution to global sea level rise. We compile historic and recent shipboard measurements of hydrography and velocity to provide a comprehensive view on water mass distribution, pathways, along-path transformation and long-term temperature changes of abyssal waters in the western South and Equatorial Atlantic. We are able to confirm previous results showing that the northwest corner of the Brazil Basin represents a splitting point for the southward/northward flow of NADW/AABW. The available measurements sample water mass transformation along the two major routes for deep and bottom waters in the tropical to South Atlantic - along the deep western boundary and eastward, parallel to the equator - as well as the hot spots of extensive mixing. We find lower NADW and lighter AABW to form a highly interactive transition layer in the northern Brazil Basin. The AABW north of 5°S is relatively homogeneous with only lighter AABW being able to pass through the Equatorial Channel (EQCH) into the North Atlantic. Spanning a period of 26 years, our data also allow an estimation of long-term temperature trends in abyssal waters. We find a warming of 2.5 ± 0.7•10-3 °C yr-1 of the waters in the northern Brazil Basin being colder than 0.6 °C throughout the period 1989-2014 and can relate that warming to a thinning of the dense AABW layer. While isopycnal heave is the dominant effect defining the vertical distribution of temperature trends on isobars, we also find temperature changes on isopycnals in the transition layer the lower NADW

  3. The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Satellite observations.

    Science.gov (United States)

    Guerrero, Raul A; Piola, Alberto R; Fenco, Harold; Matano, Ricardo P; Combes, Vincent; Chao, Yi; James, Corinne; Palma, Elbio D; Saraceno, Martin; Strub, P Ted

    2014-11-01

    Satellite-derived sea surface salinity (SSS) data from Aquarius and SMOS are used to study the shelf-open ocean exchanges in the western South Atlantic near 35°S. Away from the tropics, these exchanges cause the largest SSS variability throughout the South Atlantic. The data reveal a well-defined seasonal pattern of SSS during the analyzed period and of the location of the export of low-salinity shelf waters. In spring and summer, low-salinity waters over the shelf expand offshore and are transferred to the open ocean primarily southeast of the river mouth (from 36°S to 37°30'S). In contrast, in fall and winter, low-salinity waters extend along a coastal plume and the export path to the open ocean distributes along the offshore edge of the plume. The strong seasonal SSS pattern is modulated by the seasonality of the along-shelf component of the wind stress over the shelf. However, the combined analysis of SSS, satellite-derived sea surface elevation and surface velocity data suggest that the precise location of the export of shelf waters depends on offshore circulation patterns, such as the location of the Brazil Malvinas Confluence and mesoscale eddies and meanders of the Brazil Current. The satellite data indicate that in summer, mixtures of low-salinity shelf waters are swiftly driven toward the ocean interior along the axis of the Brazil/Malvinas Confluence. In winter, episodic wind reversals force the low-salinity coastal plume offshore where they mix with tropical waters within the Brazil Current and create a warmer variety of low-salinity waters in the open ocean. Satellite salinity sensors capture low-salinity detrainment events from shelves SW Atlantic low-salinity detrainments cause highest basin-scale variability In summer low-salinity detrainments cause extended low-salinity anomalies.

  4. Impacts of canonical and Modoki El Niño on tropical Atlantic SST

    Science.gov (United States)

    Amaya, Dillon J.; Foltz, Gregory R.

    2014-02-01

    The impacts of canonical and Modoki El Niño on tropical Atlantic sea surface temperature (SST) are quantified using composite analysis. Results show that El Niño Modoki fails to produce significant warming in the tropical Atlantic, in contrast to the well known warming following canonical El Niño events. El Niño Modoki instead induces significant cooling in the northeastern tropical Atlantic and near-neutral conditions elsewhere in the tropical Atlantic. It is shown that the difference in SST response stems primarily from a much stronger Pacific/North American (PNA) teleconnection pattern and stronger atmospheric Kelvin wave response during canonical events compared to Modoki. The stronger PNA pattern and Kelvin waves during canonical events generate anomalously weak surface winds in the tropical North Atlantic, driving anomalously weak evaporative cooling and warmer SSTs. Past research has shown significant decadal variability in the frequency of noncanonical El Niños relative to canonical events. If such variability continues, it is likely that the impact of El Niño on tropical Atlantic SST will also fluctuate from one decade to the next.

  5. PBDEs in the blubber of marine mammals from coastal areas of São Paulo, Brazil, southwestern Atlantic.

    Science.gov (United States)

    Yogui, G T; Santos, M C O; Bertozzi, C P; Sericano, J L; Montone, R C

    2011-12-01

    Limited information is available in the literature on the levels of brominated flame retardants in the southern hemisphere. This study presents concentrations of polybrominated diphenyl ethers (PBDEs) in the blubber of small cetaceans from the coast of São Paulo (Brazil), southwestern Atlantic. PBDE levels were highest in Stenella frontalis (770 ng g(-1) lipid) followed by Steno bredanensis (475 ng g(-1) lipid), Sotalia guianensis (65.6 ng g(-1) lipid), Tursiopstruncatus (64.2 ng g(-1) lipid) and Pontoporia blainvillei (60.3 ng g(-1) lipid). In general, continental shelf individuals exhibited higher contamination than inshore animals. This might be related to larger prey items consumed by continental shelf dolphins. The pattern of contamination indicates that Penta-BDE commercial mixtures are a major source of PBDEs to top predators in the southwestern Atlantic. Congeners found in Octa-BDE formulations were not detected in the investigated animals. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Historical biogeography in tropical Atlantic populations of Cladophoropsis membranacea and related species

    NARCIS (Netherlands)

    Kooistra, Wiebe Hendrik Cornelis Frederik

    1993-01-01

    The Tethys was an equatorial sea that came into existence some 200 million years ago and closed about 12 million years ago thereby fragmenting the pan-tropical marine flora. The tropical provinces of the eastern Pacific, the lndo-West Pacific, the eastern Atlantic, and the Caribbean are today's

  7. Atlantic Induced Pan-tropical Climate Variability in the Upper-ocean and Atmosphere

    Science.gov (United States)

    Li, X.; Xie, S. P.; Gille, S. T.; Yoo, C.

    2016-02-01

    During the last three decades, tropical sea surface temperature (SST) exhibited dipole-like trends, with warming over the tropical Atlantic and Indo-Western Pacific but cooling over the Eastern Pacific. The Eastern Pacific cooling has recently been identified as a driver of the global warming hiatus. Previous studies revealed atmospheric bridges between the tropical Pacific, Atlantic, and Indian Ocean, which could potentially contribute to this zonally asymmetric SST pattern. However, the mechanisms and the interactions between these teleconnections remain unclear. To investigate these questions, we performed a `pacemaker' simulation by restoring the tropical Atlantic SST changes in a state-of-the-art climate model - the CESM1. Results show that the Atlantic plays a key role in initiating the tropical-wide teleconnections, and the Atlantic-induced anomalies contribute 55%-75% of the total tropical SST and circulation changes during the satellite era. A hierarchy of oceanic and atmospheric models are then used to investigate the physical mechanisms of these teleconnections: the Atlantic warming enhances atmospheric deep convection, drives easterly wind anomalies over the Indo-Western Pacific through the Kelvin wave, and westerly anomalies over the eastern Pacific as Rossby waves, in line with Gill's solution (Fig1a). These wind changes induce an Indo-Western Pacific warming via the wind-evaporation-SST effect, and this warming intensifies the La Niña-type response in the upper Pacific Ocean by enhancing the easterly trade winds and through the Bjerknes ocean-dynamical processes (Fig1b). The teleconnection finally develops into a tropical-wide SST dipole pattern with an enhanced trade wind and Walker circulation, similar as the observed changes during the satellite era. This mechanism reveals that the tropical ocean basins are more tightly connected than previously thought, and the Atlantic plays a key role in the tropical climate pattern formation and further the

  8. Evolution of Interhemispheric Sea-Surface Temperature Contrast in the Tropical Atlantic During Termination I

    Science.gov (United States)

    Kim, J.

    2001-12-01

    Meteorological and oceanographic studies show that interannual and decadal variability in tropical Atlantic sea-surface temperature (SST) strongly influences the climates over northeast Brazil, sub-Saharan Africa, as well as the Central American and Caribbean regions. In this context, it is worthwhile to reconstruct spatial temperature patterns for the longer-term tropical Atlantic SST history. In this study, a high-resolution alkenone-derived SST record from the subtropical eastern South Atlantic (core GeoB 1023-5) is compared with one from the tropical western North Atlantic (core M35003-4). This comparison reveals synchronous SST variations between both near equatorial Atlantic regions during the Heinrich Event 1 (H1) (18-15.5 cal kyr B.P.), but dipole-like SST variations during the Younger Dryas (YD) (13-11.5 cal kyr B.P.). To assess the relationship of SST variations between both regions, we calculated SST differences between cores GeoB 1023-5 and M35003-4, and compared it with the coccolithophorid Florisphaera profunda abundance record from the equatorial eastern Atlantic (core RC24-08) as an indicator of variations in intensity of south-easterly trade winds [McIntyre and Molfino, 1996]. This comparison suggests that synchronous warming in both regions during the H1 can be attributed to a reduced northward heat transport from the warm equatorial Atlantic to the cold high-latitude North Atlantic linked to the slowdown of thermohaline circulation overturning during cold events under full glacial conditions. However, dipole-like SST variations during the YD is probably more associated with strengthened south-easterly trade winds, which led to a strong upwelling-related cooling in the eastern South Atlantic region and concurrently enhanced advection of warm subtropical South Atlantic waters to the tropical western Atlantic during that time. Accordingly, a coupled oceanic-atmospheric process created a warm pool in the tropical western Atlantic and thus a dipole

  9. North Atlantic Basin Tropical Cyclone Activity in Relation to Temperature and Decadal- Length Oscillation Patterns

    Science.gov (United States)

    Wilson, Robert M.

    2009-01-01

    Yearly frequencies of North Atlantic basin tropical cyclones, their locations of origin, peak wind speeds, average peak wind speeds, lowest pressures, and average lowest pressures for the interval 1950-2008 are examined. The effects of El Nino and La Nina on the tropical cyclone parametric values are investigated. Yearly and 10-year moving average (10-yma) values of tropical cyclone parameters are compared against those of temperature and decadal-length oscillation, employing both linear and bi-variate analysis, and first differences in the 10-yma are determined. Discussion of the 2009 North Atlantic basin hurricane season, updating earlier results, is given.

  10. The salinity signature of the cross-shelf exchanges in the Southwestern Atlantic Ocean: Numerical simulations.

    Science.gov (United States)

    Matano, Ricardo P; Combes, Vincent; Piola, Alberto R; Guerrero, Raul; Palma, Elbio D; Ted Strub, P; James, Corinne; Fenco, Harold; Chao, Yi; Saraceno, Martin

    2014-11-01

    A high-resolution model is used to characterize the dominant patterns of sea surface salinity (SSS) variability generated by the freshwater discharges of the Rio de la Plata (RdlP) and the Patos/Mirim Lagoon in the southwestern Atlantic region. We identify three dominant modes of SSS variability. The first two, which have been discussed in previous studies, represent the seasonal and the interannual variations of the freshwater plumes over the continental shelf. The third mode of SSS variability, which has not been discussed hitherto, represents the salinity exchanges between the shelf and the deep ocean. A diagnostic study using floats and passive tracers identifies the pathways taken by the freshwater plumes. During the austral winter (JJA) , the plumes leave the shelf region north of the BMC. During the austral summer (DJF), the plumes are entrained more directly into the BMC. A sensitivity study indicates that the high - frequency component of the wind stress forcing controls the vertical structure of the plumes while the low-frequency component of the wind stress forcing and the interannual variations of the RdlP discharge controls the horizontal structure of the plumes. Dynamical analysis reveals that the cross-shelf flow has a dominant barotropic structure and, therefore, the SSS anomalies detected by Aquarius represent net mass exchanges between the shelf and the deep ocean. The net cross-shelf volume flux is 1.21 Sv. This outflow is largely compensated by an inflow from the Patagonian shelf.

  11. The influence of the Brazil and Malvinas Currents on the Southwestern Atlantic Shelf circulation

    Directory of Open Access Journals (Sweden)

    R. P. Matano

    2010-11-01

    Full Text Available The oceanic circulation over the southwestern Atlantic shelf is influenced by large tidal amplitudes, substantial freshwater discharges, high wind speeds and – most importantly – by its proximity to two of the largest western boundary currents of the world ocean: the Brazil and Malvinas currents. This review article aims to discriminate the dynamical processes controlling the interaction between this extensive shelf region and the deep-ocean. The discussion is focused on two broad regions: the South Brazil Bight to the north, and Patagonia to the south. The exchanges between the Brazil Current and the South Brazil Bight are characterized by the intermittent development of eddies and meanders of the Brazil Current at the shelfbreak. However, it is argued that this is not the only – nor the most important – influence of the Brazil Current on the shelf. Numerical simulations show that the thermohaline structure of the South Brazil Bight can be entirely ascribed to steady state, bottom boundary layer interactions between the shelf and the Brazil Current. The Malvinas Current does not show the development of eddies and meanders, but its influence on the Patagonian shelf is not less important. Models and observations indicate that the Malvinas Current not only controls the shelfbreak dynamics and cross-shelf exchanges but also influences the circulation in the shelf's interior.

  12. Impacts of Tropical North Atlantic SST on Western North Pacific Landfalling Tropical Cyclones

    Science.gov (United States)

    Zhang, W.; Gao, S.; Chen, Z.

    2017-12-01

    This study examines the impacts of tropical North Atlantic (TNA) sea surface temperature (SST) anomaly (SSTA) on tropical cyclones (TCs) making landfall over East Asia. We find that TNA SSTA has significant negative correlations with the frequency of TCs making landfall over China, Vietnam, Korea and Japan, and the entire East Asia. TNA SST influences the frequency of TC landfalls over these regions by regulating TC genesis location and frequency and steering flow associated with modulated environmental conditions. During cold TNA SST years, larger low-level relative vorticity and weaker vertical wind shear lead to more TC formations in the northern SCS and to the east of Philippines, and larger low-level relative vorticity, higher mid-level relative humidity, and weaker vertical wind shear result in more TC formations over the eastern part of WNP. Anomalous northeasterly steering flow favors more TCs to move westward or west-northwestward and make landfall over Vietnam, South China and Taiwan Island and thus in the entire China, and more TCs take regular northeastward recurving tracks and make landfall over Korea and Japan because of insignificant steering flow anomalies in the vicinity. The modulation of large-scale environments by TNA SSTA may be through two possible pathways proposed in previous studies, i.e., Indian Ocean relaying effect and subtropical eastern Pacific relaying effect. Our results suggest that TNA SSTA is a potential predictor for the frequency of TCs making landfall over China, Vietnam, Korea and Japan, and the entire East Asia.

  13. Decadal oxygen change in the eastern tropical North Atlantic

    Directory of Open Access Journals (Sweden)

    J. Hahn

    2017-07-01

    Full Text Available Repeat shipboard and multi-year moored observations obtained in the oxygen minimum zone (OMZ of the eastern tropical North Atlantic (ETNA were used to study the decadal change in oxygen for the period 2006–2015. Along 23° W between 6 and 14° N, oxygen decreased with a rate of −5.9 ± 3.5 µmol kg−1 decade−1 within the depth covering the deep oxycline (200–400 m, while below the OMZ core (400–1000 m oxygen increased by 4.0 ± 1.6 µmol kg−1 decade−1 on average. The inclusion of these decadal oxygen trends in the recently estimated oxygen budget for the ETNA OMZ suggests a weakened ventilation of the upper 400 m, whereas the ventilation strengthened homogeneously below 400 m. The changed ventilation resulted in a shoaling of the ETNA OMZ of −0.03 ± 0.02 kg m−3 decade−1 in density space, which was only partly compensated by a deepening of isopycnal surfaces, thus pointing to a shoaling of the OMZ in depth space as well (−22 ± 17 m decade−1. Based on the improved oxygen budget, possible causes for the changed ventilation are analyzed and discussed. Largely ruling out other ventilation processes, the zonal advective oxygen supply stands out as the most probable budget term responsible for the decadal oxygen changes.

  14. The Impact of Canonical and Non-canonical El Niño on Atlantic Tropical Cyclone Activity: High-resolution Tropical Channel Model Simulations

    Science.gov (United States)

    Patricola, C. M.; Chang, P.; Saravanan, R.

    2013-12-01

    Tropical Pacific sea surface temperature (SST) variability during the El Niño-Southern Oscillation (ENSO) influences seasonal Atlantic tropical cyclone activity by modulating vertical wind shear and tropospheric temperature in the tropical Atlantic, with warmer than average SST during El Niño suppressing Atlantic tropical cyclones. The location of maximum SST warming during El Niño varies from the East Pacific (canonical) to Central Pacific (non-canonical/Modoki). This study investigates how the location and magnitude of maximum tropical Pacific warming impacts Atlantic tropical cyclones, and through what mechanisms. Climate simulations are performed to supplement observationally based studies, which yield conflicting results and rely on a relatively short data record that is complicated by factors other than ENSO, such as Atlantic SST variability. The simulations are run with the Weather Research and Forecasting (WRF) model configured as a tropical channel model at a relatively fine horizontal resolution of 27 km compared to the current generation of global climate models that typically use a 50 - 100 km grid. Monthly climatological SST is prescribed in the control simulation, and mechanistic experiments are forced by tropical Pacific SST patterns characteristic of Central Pacific and East Pacific El Niño. Seasonal accumulated cyclone energy is used to evaluate the response in Atlantic tropical cyclone activity to Central and East Pacific El Niño, and the response in atmospheric conditions relevant for tropical cyclones is diagnosed using a genesis potential index.

  15. Molecular and Morphological Differentiation of Common Dolphins (Delphinus sp.) in the Southwestern Atlantic: Testing the Two Species Hypothesis in Sympatry

    Science.gov (United States)

    Cunha, Haydée A.; de Castro, Rocio Loizaga; Secchi, Eduardo R.; Crespo, Enrique A.; Lailson-Brito, José; Azevedo, Alexandre F.; Lazoski, Cristiano; Solé-Cava, Antonio M.

    2015-01-01

    The taxonomy of common dolphins (Delphinus sp.) has always been controversial, with over twenty described species since the original description of the type species of the genus (Delphinus delphis Linnaeus, 1758). Two species and four subspecies are currently accepted, but recent molecular data have challenged this view. In this study we investigated the molecular taxonomy of common dolphins through analyses of cytochrome b sequences of 297 individuals from most of their distribution. We included 37 novel sequences from the Southwestern Atlantic Ocean, a region where the short- and long-beaked morphotypes occur in sympatry, but which had not been well sampled before. Skulls of individuals from the Southwestern Atlantic were measured to test the validity of the rostral index as a diagnostic character and confirmed the presence of the two morphotypes in our genetic sample. Our genetic results show that all common dolphins in the Atlantic Ocean belong to a single species, Delphinus delphis. According to genetic data, the species Delphinus capensis is invalid. Long-beaked common dolphins from the Northeastern Pacific Ocean may constitute a different species. Our conclusions prompt the need for revision of currently accepted common dolphin species and subspecies and of Delphinus delphis distribution. PMID:26559411

  16. Diversity and Distribution Patterns of Cetaceans in the Subtropical Southwestern Atlantic Outer Continental Shelf and Slope

    Science.gov (United States)

    Di Tullio, Juliana Couto; Gandra, Tiago B. R.; Zerbini, Alexandre N.; Secchi, Eduardo R.

    2016-01-01

    Temporal and spatial patterns of cetacean diversity and distribution were investigated through eight ship-based surveys carried out during spring and autumn between 2009 and 2014 on the outer continental shelf (~150m) and slope (1500m) off southeastern and southern Brazil (~23°S to ~34°S). The survey area was divided into southeast and south areas according to their oceanographic characteristics. Twenty-one species were observed in 503 sightings. The overall number of species was similar between the two areas, though it was higher in the spring in the south area. Five species were dominant and diversity varied more seasonally than spatially. ANOVA and kernel analyses showed that overall cetacean densities were higher in spring compared to autumn. Physeter macrocephalus, the most frequent species, concentrated throughout the south area at depths over 1000m in both seasons. Despite the overlapped occurrence at a broader scale, small delphinids presented latitudinal and in-offshore gradients as well as seasonal variation in distribution patterns, which could indicate habitat partitioning between some species. Delphinus delphis was only recorded in the south and its density decreased in areas where the presence of Stenella frontalis increased, mainly beyond the 250m isobath. Densities of S. longirostris and S. attenuata increased in lower latitudes and beyond the shelf break. The large delphinids Tursiops truncatus and Globicephala melas formed mixed groups in many occasions and were observed along the study area around depths of 500m. Grampus griseus was twice as frequent in the south area and densities increased in waters deeper than 600m. As expected, densities of both small and large migratory whales were higher during spring, over the continental slope, in the southeast area. The results presented here provided strong evidence on the importance of the outer continental shelf and slope to a diverse community of cetaceans occurring in the subtropical Southwestern

  17. Mammal occurrence and roadkill in two adjacent ecoregions (Atlantic Forest and Cerrado in south-western Brazil

    Directory of Open Access Journals (Sweden)

    Nilton C. Cáceres

    2010-10-01

    Full Text Available This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites and frequencies of species killed by cars on roads. Sites (n = 80 within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23 were searched for records of mammals. Species surveyed in the entire region totaled 33, belonging to nine orders and 16 families. In the Cerrado, 31 species were recorded in habitats; of these, 25 were found dead on roads. In the Atlantic Forest ecoregions, however, we found 21 species in habitats, 16 of which were also found dead on roads. There was no overall significant difference between ecoregions for frequencies of occurrence in habitats or for roadkills, but there were differences between individual species. Hence, anteaters were mostly recorded in the Cerrado ecoregion, whereas caviomorph rodents tended to be more frequent in the Atlantic Forest ecoregion (seen mainly by roadkills. The greater number of species (overall and threatened and the greater abundance of species records in the Cerrado suggest that this ecoregion has a greater biodiversity and is better conserved than the Atlantic Forest ecoregion, in the state of Mato Grosso do Sul, south-western Brazil.

  18. Environmental forcing of nitrogen fixation in the eastern tropical and sub-tropical North Atlantic Ocean.

    Science.gov (United States)

    Rijkenberg, Micha J A; Langlois, Rebecca J; Mills, Matthew M; Patey, Matthew D; Hill, Polly G; Nielsdóttir, Maria C; Compton, Tanya J; Laroche, Julie; Achterberg, Eric P

    2011-01-01

    During the winter of 2006 we measured nifH gene abundances, dinitrogen (N(2)) fixation rates and carbon fixation rates in the eastern tropical and sub-tropical North Atlantic Ocean. The dominant diazotrophic phylotypes were filamentous cyanobacteria, which may include Trichodesmium and Katagnymene, with up to 10(6) L(-1)nifH gene copies, unicellular group A cyanobacteria with up to 10(5) L(-1)nifH gene copies and gamma A proteobacteria with up to 10(4) L(-1)nifH gene copies. N(2) fixation rates were low and ranged between 0.032-1.28 nmol N L(-1) d(-1) with a mean of 0.30 ± 0.29 nmol N L(-1) d(-1) (1σ, n = 65). CO(2)-fixation rates, representing primary production, appeared to be nitrogen limited as suggested by low dissolved inorganic nitrogen to phosphate ratios (DIN:DIP) of about 2 ± 3.2 in surface waters. Nevertheless, N(2) fixation rates contributed only 0.55 ± 0.87% (range 0.03-5.24%) of the N required for primary production. Boosted regression trees analysis (BRT) showed that the distribution of the gamma A proteobacteria and filamentous cyanobacteria nifH genes was mainly predicted by the distribution of Prochlorococcus, Synechococcus, picoeukaryotes and heterotrophic bacteria. In addition, BRT indicated that multiple a-biotic environmental variables including nutrients DIN, dissolved organic nitrogen (DON) and DIP, trace metals like dissolved aluminum (DAl), as a proxy of dust inputs, dissolved iron (DFe) and Fe-binding ligands as well as oxygen and temperature influenced N(2) fixation rates and the distribution of the dominant diazotrophic phylotypes. Our results suggest that lower predicted oxygen concentrations and higher temperatures due to climate warming may increase N(2) fixation rates. However, the balance between a decreased supply of DIP and DFe from deep waters as a result of more pronounced stratification and an enhanced supply of these nutrients with a predicted increase in deposition of Saharan dust may ultimately determine the

  19. Large-Scale Controls on Atlantic Tropical Cyclone Activity on Seasonal Time Scales

    Science.gov (United States)

    Lim, Young-Kwon; Schubert, Siegfried D.; Reale, Oreste; Molod, Andrea M.; Suarez, Max J.; Auer, Benjamin M.

    2016-01-01

    Interannual variations in seasonal tropical cyclone (TC) activity (e.g., genesis frequency and location, track pattern, and landfall) over the Atlantic are explored by employing observationally-constrained simulations with the NASA Goddard Earth Observing System version (GEOS-5) atmospheric general circulation model. The climate modes investigated are El Nino-Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), and the Atlantic Meridional Mode (AMM). The results show that the NAO and AMM can strongly modify and even oppose the well- known ENSO impacts, like in 2005, when a strong positive AMM (associated with warm SSTs and a negative SLP anomaly over the western tropical Atlantic), led to a very active TC season with enhanced TC genesis over the Caribbean Sea and a number of landfalls over North America, under a neutral ENSO condition. On the other end, the weak TC activity during 2013 (characterized by weak negative Nio index) appears caused by a NAO-induced positive SLP anomaly with enhanced vertical wind shear over the tropical North Atlantic. During 2010, the combined impact of the three modes produced positive SST anomalies across the entire low-latitudinal Atlantic and a weaker subtropical high, leading to more early recurvers and thus fewer landfalls despite enhanced TC genesis. The study provides evidence that TC number and track are very sensitive to the relative phases and intensities of these three modes, and not just to ENSO alone. Examination of seasonal predictability reveals that predictive skill of the three modes is limited over tropics to sub-tropics, with the AMM having the highest predictability over the North Atlantic, followed by ENSO and NAO.

  20. Spatial and temporal distribution of North Atlantic tropical cyclones

    African Journals Online (AJOL)

    EJIRO

    3Laboratoire de Physique de l'Atmosphère et de l'Océan , ESP-UCAD, BP 5085, Dakar-Fann, Senegal. Accepted 29 October, 2009. The aim of this work is to provide a classification of tropical ... shear are needed for tropical cyclone formation. In addition, there is also the need of a precursor in order to develop a tropical ...

  1. Positive Low Cloud and Dust Feedbacks Amplify Tropical North Atlantic Multidecadal Variability

    Science.gov (United States)

    Yuan, Tianle; Oraiopoulos, Lazaros; Zelinka, Mark; Yu, Hongbin; Norris, Joel R.; Chin, Mian; Platnick, Steven; Meyer, Kerry

    2016-01-01

    The Atlantic Multidecadal Oscillation (AMO) is characterized by a horseshoe pattern of sea surface temperature (SST) anomalies and has a wide range of climatic impacts. While the tropical arm of AMO is responsible for many of these impacts, it is either too weak or completely absent in many climate model simulations. Here we show, using both observational and model evidence, that the radiative effect of positive low cloud and dust feedbacks is strong enough to generate the tropical arm of AMO, with the low cloud feedback more dominant. The feedbacks can be understood in a consistent dynamical framework: weakened tropical trade wind speed in response to a warm middle latitude SST anomaly reduces dust loading and low cloud fraction over the tropical Atlantic, which warms the tropical North Atlantic SST. Together they contribute to appearance of the tropical arm of AMO. Most current climate models miss both the critical wind speed response and two positive feedbacks though realistic simulations of them may be essential for many climatic studies related to the AMO.

  2. Interactions Between the Thermohaline Circulation and Tropical Atlantic SST in a Coupled General Circulation Model

    Science.gov (United States)

    Miller, Ron; Jiang, Xing-Jian; Travis, Larry (Technical Monitor)

    2001-01-01

    Tropical Atlantic SST shows a (statistically well-defined) decadal time scale in a 104-year simulation of unforced variability by a coupled general circulation model (CGCM). The SST anomalies superficially resemble observed Tropical Atlantic variability (TAV), and are associated with changes in the atmospheric circulation. Brazilian rainfall is modulated with a decadal time scale, along with the strength of the Atlantic trade winds, which are associated with variations in evaporation and the net surface heat flux. However, in contrast to observed tropical Atlantic variability, the trade winds damp the associated anomalies in ocean temperature, indicating a negative feedback. Tropical SST anomalies in the CGCM, though opposed by the surface heat flux, are advected in from the Southern Hemisphere mid-latitudes. These variations modulate the strength of the thermohaline circulation (THC): warm, salty anomalies at the equator sink drawing cold, fresh mid-latitude water. Upon reaching the equator, the latter inhibit vertical overturning and advection from higher latitudes, which allows warm, salty anomalies to reform, returning the cycle to its original state. Thus, the cycle results from advection of density anomalies and the effect of these anomalies upon the rate of vertical overturning and surface advection. This decadal modulation of Tropical Atlantic SST and the thermohaline circulation is correlated with ocean heat transport to the Northern Hemisphere high latitudes and Norwegian Sea SST. Because of the central role of equatorial convection, we question whether this mechanism is present in the current climate, although we speculate that it may have operated in palaeo times, depending upon the stability of the tropical water column.

  3. Structure and Evolution of Thermohaline Staircases in Tropical North Atlantic

    National Research Council Canada - National Science Library

    Wall, Steven

    2007-01-01

    .... Salt finger convection is generally observed in mid-latitude regions, particularly in the Atlantic Ocean and Mediterranean Sea, between the hase of the mixed layer and the top of the intermediate water...

  4. Sedimentation and near-bottom currents in the South-Western Atlantic

    Science.gov (United States)

    Emelyanov, Emelyan M.

    2008-01-01

    The aims of the paper are: 1) to study the bottom relief and Late Quaternary bottom sediments of the South-Western Atlantic from the Amazon cone to the Vema Channel and Rio Grande Rise, and 2) to reconstruct recent and palaeo-Antarctic near-bottom currents (AABW). For this purpose, we used three main Parasound seismic profiles: 30 cores (up to 500 cm in length), the nanoplankton stratigraphy of 9 cores from the Brazilian lithological profile (along 24 °W), and literature sources. No soft sedimentes were found in the Vema channel; the bottom of the channel is acoustically "hard". Our geological data confirm that AABW flows mainly through this channel. The velocity of this flow should be higher than 100 cm.s-1. Only this strong current is able to rewash not only soft Holocene sediments, but also consolidated Quaternary deposits. Soft layered sediments occur at a depth less than 4200 m in the Hunter channel. Consequently, the AABW is able to flow from the Argentine Basin to the Brazil Basin only at a depth of more than 4200 m in this channel. Brown red clay or yellowish gray miopelagic clay prevail in the Brazil Deep. The age of red clay in the cores is different: Early or Late Pleistocene, or Holocene. Clay was rewashed and re-deposited in many areas of the deep. This means that the hydrodynamics sometimes was very active at a depth of 4000-5000 m in the Brazil Deep. The presence of conturite and turbidite interlayers in the red clay of the S. America continental base confirms the occurrence of a strong jet of the AABW (Deep Western Boundary current - DWBC) here. Antarctic and other diatoms were brought by AABW from Antarctica up to 10-5 °S. An unusual Pleistocene Ethmodiscus rex ooze was discovered at the latitude of 20 °S. Our data confirm the occurrence in the area between 10-5 °S of two mid-oceanic channels, one of them (EMOC) being located on a large sedimentary swell. The AABW in the cross-section from the Amazon River to the MAR flows through the Nara

  5. Extratropical Cyclones over Southwestern Atlantic Ocean: Present and Future Climates projected by RegCM4

    Science.gov (United States)

    Reboita, Michelle; Rodrigues, Marcelo; da Rocha, Rosmeri

    2017-04-01

    This study shows some of the climatological features of the extratropical cyclones in present and future climate over Southwestern Atlantic Ocean (SAO). The projections were carried out with Regional Climate Model (RegCM4) nested in HadGEM2-ES global model outputs and using representative concentration pathway 8.5 (RCP8.5) from the CMIP5. The simulations considered the South America domain suggested by CORDEX, horizontal grid spacing of 50 km, 18 sigma-pressure levels in the vertical. An objective tracking scheme based on cyclonic relative vorticity calculated using the wind at 925 hPa was used to identify the cyclones. All cyclones with relative vorticity lower than the -1.5 x 10-5 s-1 and with lifetime higher or equal 24 hours were included in the climatology. Considering the period from 1979 to 2098, RegCM4 and HadGEM2-ES project a negative trend in the frequency of the extratropical cyclones over SAO, with the biggest negative trend occuring in the latitudinal band between 40°S and 57.5°S. This result can be associated with the southward displacement of the baroclinic zone which contributes to the cyclones move to south leaving the region analyzed. The three subregions with largest cyclogenetic activity discussed in the literature (southeast coast of Brazil - RG1, coast of Uruguay and southern Brazil - RG2; east coast of Argentina - RG3) were better reproduced in RegCM4 than in HadGEM2-ES. Therefore, RegCM4 downscaling ads value in the HadGEM2-ES projections. The frequency of cyclones in present (1979-2005) and future climate (2070-2098) is higher in winter and lower in summer. Regarding the mean characteristics of the cyclones (life time, travel distance, velocity, initial relative vorticity and total average vorticity), both models successfully reproduced those obtained in the reanalysis (NCEP1, NCEP2, CFSR, ERA40 and ERA-Interim) and there are no significant differences in the future climate compared with the present.

  6. Historical North Atlantic Tropical Cyclone Tracks 1851-2005, Geographic NAD83, NOAA (2006) [atlantic_hurricane_tracks_1851_2005_NOAA_2006

    Data.gov (United States)

    Louisiana Geographic Information Center — This Historical North Atlantic Tropical Cyclone Tracks file contains the 6-hourly (0000, 0600, 1200, 1800 UTC) center locations and intensities for all subtropical...

  7. Extension of PIRATA in the tropical South-East Atlantic: an initial one ...

    African Journals Online (AJOL)

    ... as an anemometer, air temperature, humidity and short-wave solar radiation probes, and a rain gauge. The initial results from the first year of data collected by the buoy are presented with a view to providing scientific and societal motivation for the continuation of the extension of PIRATA in the tropical South-East Atlantic.

  8. Enriched mantle source for the Central Atlantic magmatic province: New supporting evidence from southwestern Europe

    Science.gov (United States)

    Callegaro, Sara; Rapaille, Cedric; Marzoli, Andrea; Bertrand, Hervé; Chiaradia, Massimo; Reisberg, Laurie; Bellieni, Giuliano; Martins, Línia; Madeira, José; Mata, João; Youbi, Nasrrddine; De Min, Angelo; Azevedo, Maria Rosário; Bensalah, Mohamed Khalil

    2014-02-01

    Remnants of the Central Atlantic magmatic province (CAMP), emplaced ca. 201 Ma during the rifting phases leading to Pangaea breakup, are still preserved in southwestern Europe (SWE) in the form of sills, dykes and lava flows. Low-Ti (TiO2 0.48-1.46 wt.%) tholeiitic basalts and basaltic andesites crop out as sills only in the Pyrenean area, as dykes (especially the Messejana-Plasencia dyke) from central Spain to the Atlantic coast, and as lava flows within sedimentary basins in Southern Portugal. Here we present new geochemical data (major and trace elements, mineral chemistry and combined Sr-Nd-Pb-Os analyses) on 132 samples, aiming to investigate the mantle source of these rocks and correlate them with magmatism from other areas of the CAMP. Crustal-like signatures in incompatible element patterns (Nb-Ta troughs, Pb peaks, generally shared by most CAMP rocks) and the enriched Sr-Nd-Pb isotopic characters (87Sr/86Sr200 Ma 0.70529-0.70657; 143Nd/144Nd200 Ma 0.51238-0.51225; 206Pb/204Pb200 Ma 18.15-18.48; 207Pb/204Pb200 Ma 15.57-15.68; 208Pb/204Pb200 Ma 37.99-38.52) apparently argue in favor of crustal assimilation playing an important role in the evolution of these magmas. However, the low initial 187Os/188Os values (0.1298 ± 0.0056) as well as the restricted geochemical variations shown by SWE-CAMP rocks over such a large area limit the crustal assimilation of various Iberian lithologies to small amounts. We thus locate this enrichment in the mantle source, in the form of upper and lower crustal material recycled during earlier subduction-related events. This process, while imparting crustal signatures to incompatible elements and Sr-Nd-Pb isotopes, would not alter the Os isotopic signature, dominated by the peridotite. The mixed contribution of 3-7% of local upper (pelitic) and lower (felsic granulitic) crust is sufficient to enrich a depleted mantle source, which can be either the sub-SWE lithosphere or the upper depleted asthenosphere. Similar processes of

  9. An Estimate of the North Atlantic Basin Tropical Cyclone Activity for the 2011 Hurricane Season

    Science.gov (United States)

    Wilson, Robert M.

    2011-01-01

    Estimates are presented for the expected level of tropical cyclone activity for the 2011 North Atlantic Basin hurricane season. It is anticipated that the frequency of tropical cyclones for the North Atlantic Basin during the 2011 hurricane season will be near to above the post-1995 means. Based on the Poisson distribution of tropical cyclone frequencies for the current more active interval 1995-2010, one computes P(r) = 63.7% for the expected frequency of the number of tropical cyclones during the 2011 hurricane season to be 14 plus or minus 3; P(r) = 62.4% for the expected frequency of the number of hurricanes to be 8 plus or minus 2; P(r) = 79.3% for the expected frequency of the number of major hurricanes to be 3 plus or minus 2; and P(r) = 72.5% for the expected frequency of the number of strikes by a hurricane along the coastline of the United States to be 1 plus or minus 1. Because El Nino is not expected to recur during the 2011 hurricane season, clearly, the possibility exists that these seasonal frequencies could easily be exceeded. Also examined are the effects of the El Nino-Southern Oscillation phase and climatic change (global warming) on tropical cyclone seasonal frequencies, the variation of the seasonal centroid (latitude and longitude) location of tropical cyclone onsets, and the variation of the seasonal peak wind speed and lowest pressure for tropical cyclones.

  10. Current velocity and hydrographic observations in the Southwestern North Atlantic Ocean: Subtropical Atlantic Climate Studies (STACS), 1989 (NODC Accession 9100033)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The primary objective of the STACS program are to increase our understanding of the dynamics of the North Atlantic circulation and the role of the ocean circulation...

  11. Impact of resolution and downscaling technique in simulating recent Atlantic tropical cyclone activity

    Energy Technology Data Exchange (ETDEWEB)

    Caron, Louis-Philippe; Winger, Katja [CRCMD Network, UQAM, Montreal, QC (Canada); Jones, Colin G. [Swedish Meteorological and Hydrological Institute, Rossby Centre, Norrkoping (Sweden)

    2011-09-15

    Using the global environmental multiscale (GEM) model, we investigate the impact of increasing model resolution from 2 to 0.3 on Atlantic tropical cyclone activity. There is a clear improvement in the realism of Atlantic storms with increased resolution, in part, linked to a better representation of African easterly waves. The geographical distribution of a Genesis Potential Index, composed of large-scales fields known to impact cyclone formation, coincides closely in the model with areas of high cyclogenesis. The geographical distribution of this index also improves with resolution. We then compare two techniques for achieving local high resolution over the tropical Atlantic: a limited-area model driven at the boundaries by the global 2 GEM simulation and a global variable resolution model (GVAR). The limited-area domain and high-resolution part of the GVAR model coincide geographically, allowing a direct comparison between these two downscaling options. These integrations are further compared with a set of limited-area simulations employing the same domain and resolution, but driven at the boundaries by reanalysis. The limited-area model driven by reanalysis produces the most realistic Atlantic tropical cyclone variability. The GVAR simulation is clearly more accurate than the limited-area version driven by GEM-Global. Degradation in the simulated interannual variability is partly linked to the models failure to accurately reproduce the impact of atmospheric teleconnections from the equatorial Pacific and Sahel on Atlantic cyclogenesis. Through the use of a smaller limited-area grid, driven by GEM-Global 2 , we show that an accurate representation of African Easterly Waves is crucial for simulating Atlantic tropical cyclone variability. (orig.)

  12. Species richness and distribution patterns of echinoderms in the southwestern Atlantic Ocean (34-56°S

    Directory of Open Access Journals (Sweden)

    Valeria Souto

    2014-06-01

    Full Text Available The aim of this study was to compile and analyse available historical information on echinoderms in the southwestern Atlantic Ocean in order to make a synthesis of present taxonomical knowledge, to identify patterns of geographical distribution of echinoderm assemblages and to test the validity of the current zoogeographic scheme for this group. This study was conducted on the Argentinean continental shelf, southwestern Atlantic Ocean (34-56°S. An intensive research on geo-referenced data was carried out to make a knowledge synthesis on echinoderm species and thus create a historical database. Multivariate analysis was used to analyse the faunal composition through latitudinal and bathymetric gradients as well as echinoderm associations. The results confirmed the existence of two faunal associations that correspond to the traditional zoogeographic scheme established for the Argentine Sea: the Argentinean and Magellan Provinces. The Argentinean Province had 46 widely distributed species. Of the 86 species recorded in the Magellan Province, a high percentage (25% were also found in Antarctic waters, suggesting a strong connection between the echinoderm fauna of this province and the Antarctic Region. The species richness between 34 and 56°S in the Atlantic Ocean showed a significant increase in reference to latitude, with the highest values being recorded between 46 and 56°S. In view of the high percentage of shared species with Antarctica, considered a hot-spot region in terms of echinoderm diversity, the pattern of distribution of species richness observed in our study area could correspond to a dispersion of this species from Antarctic to sub-Antarctic regions.

  13. Floristic indicators of tropical landuse systems: Evidence from mining areas in Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Sehinde Akinbiola

    2016-07-01

    Full Text Available Most forests in the tropics have not only been reduced in size but have also experienced forest degradation. The delicate balance of the components of the forest ecosystem has been altered largely by the landuse systems which have resulted in the disappearance of some species and the introduction of new ones. In order to understand the influence of human disturbance caused by artisanal mining on plant biodiversity and the physical environment, this study assessed changes in vegetation characteristics using plant functional groups, such as invasive, pioneer and understory species. The study was conducted at two sites in two Southwestern states of Nigeria, Itagunmodi in Atakumosa West Local Government Area of Osun State and Olode in Oluyole Local Government Area of Oyo State. Complete enumerations of woody, non-woody and herbaceous plant species were carried out in 20 m by 20 m plots selected using stratified random sampling as representative of landuse classes: freshly mined (6 months and a control plot (secondary forest. The results showed that the control plot in Itagunmodi had undergone degradation as indicated by the presence of Alchornea laxiflora, Geophilia obvallata, Musa sapientum,Elaeis guineensis and Keetia hispida. However, if left undisturbed, it has the potential of regeneration back to its original state because of its woody tree species composition and lianas (Triclisia gilletii. In addition the forest soils in the mines had been exposed to direct insolation for a long period, and the soil structure and texture have been affected, consequently altering the viability of the seed bank. Poaceae and Papilionoideae were the most common in the freshly mined plots while invasive species were the most common in abandoned mined plots. In conclusion, the floristic composition in the mining sites has been altered and there was no clear evidence that regrowth would bring restoration of the lost ecosystem services.

  14. Low oxygen eddies in the eastern tropical North Atlantic

    DEFF Research Database (Denmark)

    Grundle, D. S.; Löscher, C. R.; Krahmann, G.

    2017-01-01

    Nitrous oxide (N2O) is a climate relevant trace gas, and its production in the ocean generally increases under suboxic conditions. The Atlantic Ocean is well ventilated, and unlike the major oxygen minimum zones (OMZ) of the Pacific and Indian Oceans, dissolved oxygen and N2O concentrations in th...

  15. Coupling of equatorial Atlantic surface stratification to glacial shifts in the tropical rainbelt.

    Science.gov (United States)

    Portilho-Ramos, R C; Chiessi, C M; Zhang, Y; Mulitza, S; Kucera, M; Siccha, M; Prange, M; Paul, A

    2017-05-08

    The modern state of the Atlantic meridional overturning circulation promotes a northerly maximum of tropical rainfall associated with the Intertropical Convergence Zone (ITCZ). For continental regions, abrupt millennial-scale meridional shifts of this rainbelt are well documented, but the behavior of its oceanic counterpart is unclear due the lack of a robust proxy and high temporal resolution records. Here we show that the Atlantic ITCZ leaves a distinct signature in planktonic foraminifera assemblages. We applied this proxy to investigate the history of the Atlantic ITCZ for the last 30,000 years based on two high temporal resolution records from the western Atlantic Ocean. Our reconstruction indicates that the shallowest mixed layer associated with the Atlantic ITCZ unambiguously shifted meridionally in response to changes in the strength of the Atlantic meridional overturning with a southward displacement during Heinrich Stadials 2-1 and the Younger Dryas. We conclude that the Atlantic ITCZ was located at ca. 1°S (ca. 5° to the south of its modern annual mean position) during Heinrich Stadial 1. This supports a previous hypothesis, which postulates a southern hemisphere position of the oceanic ITCZ during climatic states with substantially reduced or absent cross-equatorial oceanic meridional heat transport.

  16. Tropical Rain Forest and Climate Dynamics of the Atlantic Lowland, Southern Brazil, during the Late Quaternary

    Science.gov (United States)

    Behling, Hermann; Negrelle, Raquel R. B.

    2001-11-01

    Palynological analysis of a core from the Atlantic rain forest region in Brazil provides unprecedented insight into late Quaternary vegetational and climate dynamics within this southern tropical lowland. The 576-cm-long sediment core is from a former beach-ridge "valley," located 3 km inland from the Atlantic Ocean. Radio-carbon dates suggest that sediment deposition began prior to 35,000 14C yr B.P. Between ca. 37,500 and ca. 27,500 14C yr B.P. and during the last glacial maximum (LGM; ca. 27,500 to ca. 14,500 14C yr B.P.), the coastal rain forest was replaced by grassland and patches of cold-adapted forest. Tropical trees, such as Alchornea, Moraceae/Urticaceae, and Arecaceae, were almost completely absent during the LGM. Furthermore, their distributions were shifted at least 750 km further north, suggesting a cooling between 3°C and 7°C and a strengthening of Antarctic cold fronts during full-glacial times. A depauperate tropical rain forest developed as part of a successional sequence after ca. 12,300 14C yr B.P. There is no evidence that Araucaria trees occurred in the Atlantic lowland during glacial times. The rain forest was disturbed by marine incursions during the early Holocene period until ca. 6100 14C yr B.P., as indicated by the presence of microforaminifera. A closed Atlantic rain forest then developed at the study site.

  17. The PIRATA Observing System in the Tropical Atlantic: Enhancements and perspectives

    Science.gov (United States)

    Hernandez, Fabrice; Araujo, Moacyr; Bourlès, Bernard; Brandt, Peter; Campos, Edmo; Giordani, Hervé; Lumpkin, Rick; McPhaden, Michael J.; Nobre, Paulo; Saravanan, Ramalingam

    2017-04-01

    PIRATA (Prediction and Research Moored Array in the Tropical Atlantic) is a multinational program established to improve our knowledge and understanding of ocean-atmosphere variability in the tropical Atlantic, a region that strongly influences the regional hydro-climates and, consequently, the economies of the regions bordering the Atlantic Ocean (e.g. West Africa, North-Eastern Brazil, the West Indies and the United States). PIRATA is motivated not only by fundamental scientific questions but also by societal needs for improved prediction of climatic variability and its impacts. PIRATA, initiated in 1997, is based around an array of moored buoys providing meteorological and oceanographic measurements transmitted in real-time, disseminated via GTS and Global Data Servers. Then, through yearly mooring maintenance, recorded high frequency data are collected and calibrated. The dedicated cruises of yearly maintenance allow complementary acquisition of a large number of measurements along repeated ship track lines and also provide platforms for deployments of other components of the observing system. Several kinds of operations are carried out in collaboration with other international programs. PIRATA provides invaluable data for numerous and varied applications, among which are analyses of climate variability on intraseasonal-to-decadal timescales, equatorial dynamics, mixed-layer temperature and salinity budgets, air-sea fluxes, data assimilation, and weather and climate forecasts. PIRATA is now 20 years old, well established and recognized as the backbone of the tropical Atlantic sustained observing system. Several enhancements have been achieved during recent years, including progressive updating of mooring systems and sensors, also in collaborations with and as a contribution to other programs (such as EU PREFACE and AtlantOS). Recent major accomplishments in terms of air-sea exchanges and climate predictability will be highlighted in this presentation. Future

  18. Orbital Forcing driving climate variability on Tropical South Atlantic

    Science.gov (United States)

    Oliveira, A. S.; Baker, P. A.; Silva, C. G.; Dwyer, G. S.; Chiessi, C. M.; Rigsby, C. A.; Ferreira, F.

    2017-12-01

    Past research on climate response to orbital forcing in tropical South America has emphasized on high precession cycles influencing low latitude hydrologic cycles, and driving the meridional migration of Intertropical Convergence Zone (ITCZ).However, marine proxy records from the tropical Pacific Ocean showed a strong 41-ka periodicities in Pleistocene seawater temperature and productivity related to fluctuations in Earth's obliquity. It Indicates that the western Pacific ITCZ migration was influenced by combined precession and obliquity changes. To reconstruct different climate regimes over the continent and understand the orbital cycle forcing over Tropical South America climate, hydrological reconstruction have been undertaken on sediment cores located on the Brazilian continental slope, representing the past 1.6 million years. Core CDH 79 site is located on a 2345 m deep seamount on the northern Brazilian continental slope (00° 39.6853' N, 44° 20.7723' W), 320 km from modern coastline of the Maranhão Gulf. High-resolution XRF analyses of Fe, Ti, K and Ca are used to define the changes in precipitation and sedimentary input history of Tropical South America. The response of the hydrology cycle to orbital forcing was studied using spectral analysis.The 1600 ka records of dry/wet conditions presented here indicates that orbital time-scale climate change has been a dominant feature of tropical climate. We conclude that the observed oscillation reflects variability in the ITCZ activity associated with the Earth's tilt. The prevalence of the eccentricity and obliquity signals in continental hydrology proxies (Ti/Ca and Fe/K) as implicated in our precipitation records, highlights that these orbital forcings play an important role in tropics hydrologic cycles. Throughout the Quaternary abrupt shifts of tropical variability are temporally correlated with abrupt climate changes and atmospheric reorganization during Mid-Pleistocene Transition and Mid-Brunhes Events

  19. Tropical Cyclone Exposure for U.S. waters within the North Atlantic Ocean basin, 1900-2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data represent modeled, historical exposure of U.S. offshore and coastal waters to tropical cyclone activity within the North Atlantic Ocean basin. BOEM Outer...

  20. A Reassessment of the Integrated Impact of Tropical Cyclones on Surface Chlorophyll in the Western Subtropical North Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Foltz, Gregory R.; Balaguru, Karthik; Leung, Lai-Yung R.

    2015-02-28

    The impact of tropical cyclones on surface chlorophyll concentration is assessed in the western subtropical North Atlantic Ocean during 1998–2011. Previous studies in this area focused on individual cyclones and gave mixed results regarding the importance of tropical cyclone-induced mixing for changes in surface chlorophyll. Using a more integrated and comprehensive approach that includes quantification of cyclone-induced changes in mixed layer depth, here it is shown that accumulated cyclone energy explains 22% of the interannual variability in seasonally-averaged (June–November) chlorophyll concentration in the western subtropical North Atlantic, after removing the influence of the North Atlantic Oscillation (NAO). The variance explained by tropical cyclones is thus about 70% of that explained by the NAO, which has well-known impacts in this region. It is therefore likely that tropical cyclones contribute significantly to interannual variations of primary productivity in the western subtropical North Atlantic during the hurricane season.

  1. On the geographic distribution of Scarabaeus (Scarabaeus aegyptiacus Stolfa, 1938 (Coleoptera: Scarabaeidae: first record from Atlantic Sahara (southwestern Morocco

    Directory of Open Access Journals (Sweden)

    J. L. Ruiz

    2017-03-01

    Full Text Available Scarabaeus aegyptiacus is a species widely distributed from the Arabian Peninsula to Morocco, occupying mainly arid and desert regions. Despite its wide geographic range, the number of known localities is very low (ten locations and its populations seem apparently fragmented and spaced. During a recent field survey in southwestern Morocco, we found a population of S. aegyptiacus in a rocky steppe (hamada near Msied (Tan-Tan province, Guelmin-Smara region, which constitutes the first record from Atlantic Sahara and extends about 1000 km to the southwest its known distribution. The specimens were found in a water cistern (“matfiya” in the local language, infrastructure that acts as a deadly trap for many animals, especially reptiles, amphibians and epigean arthropods, whose negative effect on invertebrate communities has not yet been evaluated. Chorological information of the species is synthesized and data on the habitat are provided.

  2. An Extended Forecast of the Frequencies of North Atlantic Basin Tropical Cyclone Activity for 2009

    Science.gov (United States)

    Wilson, Robert M.

    2009-01-01

    An extended forecast of the frequencies for the 2009 North Atlantic basin hurricane season is presented. Continued increased activity during the 2009 season with numbers of tropical cyclones, hurricanes, and major hurricanes exceeding long-term averages are indicated. Poisson statistics for the combined high-activity intervals (1950-1965 and 1995-2008) give the central 50% intervals to be 9-14, 5-8, and 2-4, respectively, for the number of tropical cyclones, hurricanes, and major hurricanes, with a 23.4% chance of exceeding 14 tropical cyclones, a 28% chance of exceeding 8 hurricanes, and a 31.9% chance of exceeding 4 major hurricanes. Based strictly on the statistics of the current high-activity interval (1995-2008), the central 50% intervals for the numbers of tropical cyclones, hurricanes, and major hurricanes are 12-18, 6-10, and 3-5, respectively, with only a 5% chance of exceeding 23, 13, or 7 storms, respectively. Also examined are the first differences in 10-yr moving averages and the effects of global warming and decadal-length oscillations on the frequencies of occurrence for North Atlantic basin tropical cyclones. In particular, temperature now appears to be the principal driver of increased activity and storm strength during the current high-activity interval, with near-record values possible during the 2009 season.

  3. Three-Dimensional Structure of Thermohaline Staircases in the Tropical North Atlantic and Their Effect on Acoustic Propagation

    Science.gov (United States)

    2012-12-01

    STRUCTURE OF THERMOHALINE STAIRCASES IN THE TROPICAL NORTH ATLANTIC AND THEIR EFFECT ON ACOUSTIC PROPAGATION by Amy C. Bulters December... THERMOHALINE STAIRCASES IN THE TROPICAL NORTH ATLANTIC AND THEIR EFFECT ON ACOUSTIC PROPAGATION 5. FUNDING NUMBERS 6. AUTHOR(S) Amy C. Bulters 7...overlies cold, fresh fluid). The formation of staircases in the thermohaline structure of the ocean has been observed since the late 1960s, with

  4. A tropical Atlantic species of Melibe Rang, 1829 (Mollusca, Nudibranchia, Tethyiidae

    Directory of Open Access Journals (Sweden)

    Erika Espinoza

    2013-07-01

    Full Text Available A new species of Melibe is described based on two specimens collected in Florida. This new species is well differentiated morphologically and genetically from other species of Melibe studied to date. The four residue deletions in the cytochrome c oxidase subunit 1 protein found in all previously sequenced tropical species of Melibe sequenced (and Melibe rosea are also present in this new species. These deletions do not appear to affect important structural components of this protein but might have fitness implications. This paper provides the first confirmed record of Melibe in the tropical western Atlantic Ocean.

  5. Role of Tropical Atlantic SST Variability as a Modulator of El Nino Teleconnections

    Science.gov (United States)

    Ham, Yoo-Geun; Sung, Mi-Kyung; An, Soon-II; Schubert, Siegfried D.; Kug, Jong-Seong

    2014-01-01

    The present study suggests that the off-equatorial North Atlantic (NATL) SST warming plays a significant role in modulating El Niño teleconnection and its impact on the North Atlantic and European regions. The El Niño events accompanied by NATL SST warming exhibit south-north dipole pattern over the Western Europe to Atlantic, while the ENSO teleconnection pattern without NATL warming exhibits a Rossby wave-like pattern confined over the North Pacific and western Atlantic. Especially, the El Niño events with NATL warming show positive (negative) geopotential-height anomalies over the North Atlantic (Western Europe) which resemble the negative phase of the NAO. Consistently, it is shown using a simple statistical model that NATL SSTA in addition to the tropical Pacific SSTA leads to better prediction on regional climate variation over the North Atlantic and European regions. This role of NATL SST on ENSO teleconnection is also validated and discussed in a long term simulation of coupled global circulation model (CGCM).

  6. Identification of an assembly site for migratory and tropical seabirds in the South Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    B. John Hughes

    2015-07-01

    Full Text Available Seabirds are good indicators of wider biodiversity and where they assemble in large numbers signifies sites important to many marine faunal species. Few such large assemblage sites have been identified and none in pelagic waters has been identified in the tropical Atlantic Ocean despite their importance for resident seabirds and those ‘on passage’ during migration. Here, we identify the likely location of just such an assembly site and provide preliminary information about the distribution of pelagic seabirds around Ascension Island in the tropical South Atlantic Ocean using a combination of trans-equatorial seabird migrant tracking data, records of at-sea surveys and land counts of seabirds returning from foraging trips. We found that waters north–north-west of Ascension Island are used more often by seabirds than those south and east of the island. Three-fifths of the species recorded in the assembly site breed at mid- or high-latitudes and some of these migratory seabirds stopover possibly to wait for favourable winds that facilitate onward flight. Our findings are important because to the best of our knowledge no seabird assembly sites have previously been identified in tropical Atlantic Ocean pelagic waters. We provide evidence to support the aspirations of the Marine Reserves Coalition that waters in the vicinity of Ascension Island should be recognised as a sanctuary for marine wildlife and we highlight an area that is worthy of further targeted investigation.

  7. Impacts of the north and tropical Atlantic Ocean on the Antarctic Peninsula and sea ice.

    Science.gov (United States)

    Li, Xichen; Holland, David M; Gerber, Edwin P; Yoo, Changhyun

    2014-01-23

    In recent decades, Antarctica has experienced pronounced climate changes. The Antarctic Peninsula exhibited the strongest warming of any region on the planet, causing rapid changes in land ice. Additionally, in contrast to the sea-ice decline over the Arctic, Antarctic sea ice has not declined, but has instead undergone a perplexing redistribution. Antarctic climate is influenced by, among other factors, changes in radiative forcing and remote Pacific climate variability, but none explains the observed Antarctic Peninsula warming or the sea-ice redistribution in austral winter. However, in the north and tropical Atlantic Ocean, the Atlantic Multidecadal Oscillation (a leading mode of sea surface temperature variability) has been overlooked in this context. Here we show that sea surface warming related to the Atlantic Multidecadal Oscillation reduces the surface pressure in the Amundsen Sea and contributes to the observed dipole-like sea-ice redistribution between the Ross and Amundsen-Bellingshausen-Weddell seas and to the Antarctic Peninsula warming. Support for these findings comes from analysis of observational and reanalysis data, and independently from both comprehensive and idealized atmospheric model simulations. We suggest that the north and tropical Atlantic is important for projections of future climate change in Antarctica, and has the potential to affect the global thermohaline circulation and sea-level change.

  8. The Equatorial Undercurrent in the central Atlantic and its relation to tropical Atlantic variability

    NARCIS (Netherlands)

    Brandt, Peter; Funk, Andreas; Tantet, Alexis; Johns, William E.; Fischer, Jürgen

    2014-01-01

    Seasonal to interannual variations of the Equatorial Undercurrent (EUC) in the central Atlantic at 23?Ware studied using shipboard observation taken during the period 1999–2011 as well as moored velocity time series covering the period May 2005–June 2011. The sea- sonal variations are dominated by

  9. Mechanisms of meridional transport processes in the tropical Atlantic; Mechanismen meridionaler Transportprozesse im tropischen Atlantik

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, J.

    2001-07-01

    Meridional transport processes of water masses and tracers in the subtropical and tropical Atlantic are investigated using a regional eddy resolving model of the wind driven and thermohaline circulation. Analytical emphasis is on float simulations in the model which, complementary to Eulerian means, represent the Lagrangian view and give further insight into the spreading and pathways of characteristic water masses in this area. In the tropics and subtropics shallow 3-dimensional circulation cells are superimposed on the northward warm water transfer within the deep reaching thermohaline overturning cell (MOC) as part of the global ''Conveyor Belt''. Under present-day climate conditions the model shows that the equatorial thermocline is exclusively ventilated by subsurface flow within the tropical-subtropical cell (STC) of the South Atlantic. Only with a prescribed ''Conveyor-off''-Mode the STC of the North Atlantic contributes to this ventilation process with equal amounts. Throughout the year the interhemispheric transport of surface and central water masses of South Atlantic origin into the Caribbean Sea is dominated by zonal detours to the east as a consequence of the interplay of several retroflection events occuring in the North Atlantic. The eulerian mean flow field in the deep layer postulates the interhemispheric mass transport into the South Atlantic to be confined entirely to the western boundary, whereas Lagrangian means indicate intermittent eastward excursions along the equator, related to seasonally alternating zonal currents due to long Rossby waves. It was suggested that the observed characteristic eastward maximum of tracer concentrations along the equator is a consequence of rectifying effects of single or interacting equatorial waves. The model does not validate this hypothesis. The response to transport anomalies of subpolar origin and long periodicity is subject to different time-scales in both

  10. The Response of Atlantic Tropical Cyclones to Suppression of African Easterly Waves

    Science.gov (United States)

    Patricola, Christina M.; Saravanan, R.; Chang, Ping

    2018-01-01

    Atlantic tropical cyclone (TC) genesis is strongly linked with African easterly waves (AEWs) on the synoptic time scale. However, the TC-AEW relationship is unclear on interannual to climate time scales, and it is unknown whether AEWs are necessary to maintain climatological TC frequency, that is, whether TCs are limited by AEWs. We investigated the impact of AEW suppression on seasonal Atlantic TC activity using a 10-member ensemble of regional climate model simulations in which AEWs were either prescribed or removed through the lateral boundary condition. The climate model experiments produced no significant change in seasonal Atlantic TC number, indicating that AEWs are not necessary to maintain climatological basin-wide TC frequency even though TCs readily originate from these types of disturbances. This suggests that the specific type of "seedling" disturbance is unimportant for determining basin-wide seasonal Atlantic TC number and that in the absence of AEWs, TCs will generate by other mechanisms. The results imply that changes in the presence of AEWs may not be reliable predictors of seasonal variability and future change in Atlantic TC frequency.

  11. Links between tropical rainfall and North Atlantic climate during the last glacial period

    Science.gov (United States)

    Deplazes, Gaudenz; Lückge, Andreas; Peterson, Larry C.; Timmermann, Axel; Hamann, Yvonne; Hughen, Konrad A.; Röhl, Ursula; Laj, Carlo; Cane, Mark A.; Sigman, Daniel M.; Haug, Gerald H.

    2013-03-01

    During the last glacial period, the North Atlantic regionexperienced pronounced, millennial-scale alternations between cold, stadial conditions and milder interstadial conditions--commonly referred to as Dansgaard-Oeschger oscillations--as well as periods of massive iceberg discharge known as Heinrich events. Changes in Northern Hemisphere temperature, as recorded in Greenland, are thought to have affected the location of the Atlantic intertropical convergence zone and the strength of the Indian summer monsoon. Here we use high-resolution records of sediment colour--a measure of terrigenous versus biogenic content--from the Cariaco Basin off the coast of Venezuela and the Arabian Sea to assess teleconnections with the North Atlantic climate system during the last glacial period. The Cariaco record indicates that the intertropical convergence zone migrated seasonally over the site during mild stadial conditions, but was permanently displaced south of the basin during peak stadials and Heinrich events. In the Arabian Sea, we find evidence of a weak Indian summer monsoon during the stadial events. The tropical records show a more variable response to North Atlantic cooling than the Greenland temperature records. We therefore suggest that Greenland climate is especially sensitive to variations in the North Atlantic system--in particular sea-ice extent--whereas the intertropical convergence zone and Indian monsoon system respond primarily to variations in mean Northern Hemisphere temperature.

  12. A mechanism for long-term changes of Atlantic tropical cyclone intensity

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Liguang; Tao, Li [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing, Jiangsu (China)

    2011-05-15

    Although previous studies reported upward trends in the basin-wide average lifetime, annual frequency, proportion of intense hurricanes and annual accumulated power dissipation index of Atlantic tropical cyclones (TCs) over the past 30 years, the basin-wide intensity did not increase significantly with the rising sea surface temperature (SST). Observational analysis and numerical simulation conducted in this study suggest that Sahel rainfall is the key to understanding of the long-term change of Atlantic TC intensity. The long-term changes of the basin-wide TC intensity are generally associated with variations in Sahara air layer (SAL) activity and vertical wind shear in the main development region (MDR), both of which are highly correlated with Sahel rainfall. The drying Sahel corresponds to an equatorward shift in the African easterly jet and African easterly wave activity, introducing the SAL to lower latitudes and increasing the MDR vertical wind shear. As a result, Atlantic TCs are more vulnerable to the suppressing effects of the SAL and vertical wind shear. Since the SST warming, especially in the tropical Indian Ocean, is a dominant factor for the Sahel drying that occurred over the past 30 years, it is suggested that the remote effect of SST warming is important for the long-term change of Atlantic TC intensity. Although influence of the AMO warm phase that started in the early 1990s alone can provide a favorable condition for TC intensification, its influence may have been offset by the influence of the ongoing SST warming, particularly in the Indian Ocean. As a result, there was no significant trend observed in the basin-wide average and peak intensity of Atlantic TCs. (orig.)

  13. Middle Eocene paleocirculation of the southwestern Atlantic Ocean, the anteroom to an ice-house world: evidence from dinoflagellates

    Science.gov (United States)

    Raquel Guerstein, G.; Daners, Gloria; Palma, Elbio; Ferreira, Elizabete P.; Premaor, Eduardo; Amenábar, Cecilia R.; Belgaburo, Alexandra

    2016-04-01

    northward along the Southwestern Atlantic Shelf. During the Late Eocene, the endemic component is replaced by more diverse assemblages with bipolar markers of cooler, typical oceanic species and an increased number of heterotrophic protoperidiniaceans. The opening and deepening of the Tasmanian Gateway and Drake Passage and the subsequent development of an incipient Antarctic Circumpolar Current during the Oligocene disrupted the subpolar gyres and promote the extinction of the endemic species.

  14. Western tropical Pacific multidecadal variability forced by the Atlantic multidecadal oscillation

    Science.gov (United States)

    Kucharski, F.; Sun, C.; Li, J.; Jin, F. F.; Kang, I. S.; Ding, R.

    2017-12-01

    Observational analysis suggests that the western tropical Pacific (WTP) sea surface temperature (SST) shows predominant variability over multidecadal time scales, which is unlikely to be explained by the Interdecadal Pacific Oscillation. Here we show that this variability is largely explained by the remote Atlantic multidecadal oscillation (AMO). A suite of Atlantic Pacemaker experiments successfully reproduces the WTP multidecadal variability and the AMO-WTP SST connection. The AMO warm SST anomaly generates an atmospheric teleconnection to the North Pacific, which weakens the Aleutian low and subtropical North Pacific westerlies. The wind changes induce a subtropical North Pacific SST warming through wind-evaporation-SST effect, and in response to this warming, the surface winds converge towards the subtropical North Pacific from the tropics, leading to anomalous cyclonic circulation and low pressure over the WTP region. The warm SST anomaly further develops due to the SST-sea level pressure-cloud-longwave radiation positive feedback. Our findings suggest that the Atlantic Ocean acts as a key pacemaker for the western Pacific decadal climate variability.

  15. Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2014

    Science.gov (United States)

    Wilson, Robert M.

    2016-01-01

    This Technical Publication (TP) represents an extension of previous work concerning the tropical cyclone activity in the North Atlantic basin during the weather satellite era, 1960-2014, in particular, that of an article published in The Journal of the Alabama Academy of Science. With the launch of the TIROS-1 polar-orbiting satellite in April 1960, a new era of global weather observation and monitoring began. Prior to this, the conditions of the North Atlantic basin were determined only from ship reports, island reports, and long-range aircraft reconnaissance. Consequently, storms that formed far from land, away from shipping lanes, and beyond the reach of aircraft possibly could be missed altogether, thereby leading to an underestimate of the true number of tropical cyclones forming in the basin. Additionally, new analysis techniques have come into use which sometimes has led to the inclusion of one or more storms at the end of a nominal hurricane season that otherwise would not have been included. In this TP, examined are the yearly (or seasonal) and 10-year moving average (10-year moving average) values of the (1) first storm day (FSD), last storm day (LSD), and length of season (LOS); (2) frequencies of tropical cyclones (by class); (3) average peak 1-minute sustained wind speed () and average lowest pressure (); (4) average genesis location in terms of north latitudinal () and west longitudinal () positions; (5) sum and average power dissipation index (); (6) sum and average accumulated cyclone energy (); (7) sum and average number of storm days (); (8) sum of the number of hurricane days (NHD) and number of major hurricane days (NMHD); (9) net tropical cyclone activity index (NTCA); (10) largest individual storm (LIS) PWS, LP, PDI, ACE, NSD, NHD, NMHD; and (11) number of category 4 and 5 hurricanes (N4/5). Also examined are the December-May (D-M) and June-November (J-N) averages and 10-year moving average values of several climatic factors, including the (1

  16. Environmental patterns and biomass distribution of gelatinous macrozooplankton. Three study cases in the South-western Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    H. W. Mianzan

    2000-12-01

    Full Text Available Periodic swarms or blooms of gelatinous macrozooplankton have a negative effect on many human activities such as tourism, fisheries, and industry, but for several reasons (sampling procedures, underestimation of their real abundance, etc., they have often been neglected in the local literature. The high spatial resolution exercise of the South-western Atlantic anchovy Engraulis anchoita Recruitment Project (SARP was therefore also suitable for estimating standing stocks of jelly macrozooplankton, attempting to establish particular environmental patterns exerting control on the spatial distribution of these facultative carnivorous predators in coastal frontal environments. These studies were carried out through a sampling programme on board the German R/V Meteor in three different systems, convergence and divergent, in the South-western Atlantic Ocean: Region A (42°S on the Argentine shelf, characterised by tidal mixing fronts; Region B (36°S, the freshwater outflow from Río de la Plata; and Region C (28°S, under upwelling events in subtropical waters on the Brazilian shelf. In general, a dominance of gelatinous macrozooplankton, compared with the other fraction of macrozooplankton and micronekton was observed. Mean standing stock of the gelatinous zooplankton was always greater than 50% of organic carbon (org. C in every section analysed. The lobate ctenophore Mnemiopsis leidyi dominated the zooplankton biomass in Region A, Argentina. It represented 60% of total org. C and was more abundant at the stratified zone of the front. Ctenophores were also dominant in Region B, Río de la Plata, where the related species Mnemiopsis mccradyi and the cydippid ctenophore Pleurobrachia pileus comprised 81% of total org. C. Mnemiopsis was most common in areas of vertical thermal and saline stratification, while Pleurobrachia was dominant in the less stratified areas. Gelatinous zooplankton was also the principal component of the macrozooplankton biomass

  17. Amazon River enhances diazotrophy and carbon sequestration in the tropical North Atlantic Ocean.

    Science.gov (United States)

    Subramaniam, A; Yager, P L; Carpenter, E J; Mahaffey, C; Björkman, K; Cooley, S; Kustka, A B; Montoya, J P; Sañudo-Wilhelmy, S A; Shipe, R; Capone, D G

    2008-07-29

    The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousands of kilometers away from the coast by surface plumes. The nutrients delivered by these river plumes contribute to enhanced primary production in the ocean, and the sinking flux of this new production results in carbon sequestration. Here, we report that the Amazon River plume supports N(2) fixation far from the mouth and provides important pathways for sequestration of atmospheric CO(2) in the western tropical North Atlantic (WTNA). We calculate that the sinking of carbon fixed by diazotrophs in the plume sequesters 1.7 Tmol of C annually, in addition to the sequestration of 0.6 Tmol of C yr(-1) of the new production supported by NO(3) delivered by the river. These processes revise our current understanding that the tropical North Atlantic is a source of 2.5 Tmol of C to the atmosphere [Mikaloff-Fletcher SE, et al. (2007) Inverse estimates of the oceanic sources and sinks of natural CO(2) and the implied oceanic carbon transport. Global Biogeochem Cycles 21, doi:10.1029/2006GB002751]. The enhancement of N(2) fixation and consequent C sequestration by tropical rivers appears to be a global phenomenon that is likely to be influenced by anthropogenic activity and climate change.

  18. Amazon River enhances diazotrophy and carbon sequestration in the tropical North Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Bjoerkman, K. [Department of Oceanography, SOEST, University of Hawaii, Honolulu, HI (United States); Capone, D.G. [University of Southern California, Los Angeles, CA (United States). Wrigley Institute for Environmental Studies and Department of Biological Sciences; Carpenter, E.J. [San Francisco State University, Tiburon, CA (United States). Romberg Tiburon Center; Cooley, S. [University of Georgia, Athens, GA (United States). Department of Marine Sciences; Kustka, A.B. [Ruters, The State University of New Jersey, New Brunswick, NJ (United States). Institute of Marine and Coastal Sciences; Mahaffey, C. [University of Liverpool (United Kingdom). Department of Earth and Ocean Science; Montoya, J.P. [Georgia Institute of Technology, Atlanta, GA (United States). School of Biology; Sanudo-Wilhelmy, S.A. [University of Southern California, Los Angeles, CA (United States). Wrigley Institute for Environmental Studies and Department of Biological Sciences; Shipe, R. [University of California, Los Angeles, CA (United States). Department of Ecology and Evolutionary Biology and Institute of the Environment; Subramaniam, A. [Columbia University, Palisades, NY (United States). Lamont-Doherty Earth Observatory; Yager, P.L. [University of Georgia, Athens, GA (United States). Department of Marine Sciences

    2008-07-15

    The fresh water discharged by large rivers such as the Amazon is transported hundreds to thousands of kilometers away from the coast by surface plumes. The nutrients delivered by these river plumes contribute to enhanced primary production in the ocean, and the sinking flux of this new production results in carbon sequestration. Here, we report that the Amazon River plume supports N2 fixation far from the mouth and provides important pathways for sequestration of atmospheric CO2 in the western tropical North Atlantic (WTNA). We calculate that the sinking of carbon fixed by diazotrophs in the plume sequesters 1.7 Tmol of C annually, in addition to the sequestration of 0.6 Tmol of C yr-1 of the new production supported by NO3 delivered by the river. These processes revise our current understanding that the tropical North Atlantic is a source of 2.5 Tmol of C to the atmosphere [Mikaloff-Fletcher SE, et al. (2007) Inverse estimates of the oceanic sources and sinks of natural CO2 and the implied oceanic carbon transport. Global Biogeochem Cycles 21, doi:10.1029/2006GB002751]. The enhancement of N2 fixation and consequent C sequestration by tropical rivers appears to be a global phenomenon that is likely to be influenced by anthropogenic activity and climate change.

  19. Changes in the interannual variability of the tropical Pacific as a response to an equatorial Atlantic forcing

    Directory of Open Access Journals (Sweden)

    Marta Martín-Rey

    2012-09-01

    Full Text Available Previous studies have reported that the tropical Atlantic has had an influence on tropical Pacific interannual variability since the 1970s. This variability is studied in the present work, using simulations from a coupled model in the Indo-Pacific but with observed sea surface temperature (SST prescribed over the Atlantic. The interannual variability is compared with that from a control simulation in which climatological SSTs are prescribed over the Atlantic. Differences in the Pacific mean state and in its variability are found in the forced simulation as a response to a warming in the equatorial Atlantic, characterized by a cooler background state and an increase in the variability over the tropical Pacific. A striking result is that the principal modes of tropical Pacific SST interannual variability show significant differences before and after the 1970s, providing new evidence of the Atlantic influence on the Pacific Ocean. Significant cooling (warming in the equatorial Atlantic could have caused anomalous winds in the central-easter Pacific during the summer since 1970s. The thermocline depth also seems to be altered, triggering the dynamical processes involved in the development of El Niño (La Niña phenomenon in the following winter. An increase in frequency of Niño and Niña events favouring the Central Pacific (CP ones is observed in the last three decades. Further analyses using coupled models are still necessary to help us to understand the causes of this inter-basin connection.

  20. Natural and anthropogenic forcing of North Atlantic tropical cyclone track position since 1550 A.D.

    Science.gov (United States)

    Baldini, Lisa; Baldini, James; McElwaine, Jim; Frappier, Amy; Asmerom, Yemane; Liu, Kam-biu; Prufer, Keith; Ridley, Harriet; Polyak, Victor; Kennett, Douglas; Macpherson, Colin; Aquino, Valorie; Awe, Jamie; Breitenbach, Sebastian

    2016-04-01

    Over the last 30 years, North Atlantic tropical cyclones (TC) have increased in frequency, intensity, and duration in response to rising North Atlantic sea surface temperatures (SST). Here we present a 450-year record of western Caribbean TC activity reconstructed using subannually-resolved carbon and oxygen isotope ratios in a stalagmite from Yok Balum Cave, southern Belize. Western Caribbean TC activity peaked at 1650 A.D. coincident with maximum Little Ice Age cooling and decreased gradually to 1983 A.D. (the end of the record). Comparison with existing basin-wide reconstructions reveals that the dominant TC tracks corridor migrated from the western Caribbean toward the North American east coast through time. A close link with Atlantic Multidecadal Oscillation (AMO) exists throughout the record but with a clear polarity shift in the TC-AMO relationship at 1870 A.D., coincident with industrialisation. We suggest that the cause of this reversal is Greenhouse gas and aerosol emission induced changes in the relationship between the Intertropical Convergence Zone and the Bermuda High between the modern warm period and the Pre-Industrial Era. The likely impact of continued anthropogenic forcing of TC track on population centres of the western North Atlantic and Caribbean will be addressed.

  1. Can Aerosol Direct Radiative Effects Account for Analysis Increments of Temperature in the Tropical Atlantic?

    Science.gov (United States)

    da Silva, Arlindo M.; Alpert, Pinhas

    2016-01-01

    In the late 1990's, prior to the launch of the Terra satellite, atmospheric general circulation models (GCMs) did not include aerosol processes because aerosols were not properly monitored on a global scale and their spatial distributions were not known well enough for their incorporation in operational GCMs. At the time of the first GEOS Reanalysis (Schubert et al. 1993), long time series of analysis increments (the corrections to the atmospheric state by all available meteorological observations) became readily available, enabling detailed analysis of the GEOS-1 errors on a global scale. Such analysis revealed that temperature biases were particularly pronounced in the Tropical Atlantic region, with patterns depicting a remarkable similarity to dust plumes emanating from the African continent as evidenced by TOMS aerosol index maps. Yoram Kaufman was instrumental encouraging us to pursue this issue further, resulting in the study reported in Alpert et al. (1998) where we attempted to assess aerosol forcing by studying the errors of a the GEOS-1 GCM without aerosol physics within a data assimilation system. Based on this analysis, Alpert et al. (1998) put forward that dust aerosols are an important source of inaccuracies in numerical weather-prediction models in the Tropical Atlantic region, although a direct verification of this hypothesis was not possible back then. Nearly 20 years later, numerical prediction models have increased in resolution and complexity of physical parameterizations, including the representation of aerosols and their interactions with the circulation. Moreover, with the advent of NASA's EOS program and subsequent satellites, atmospheric aerosols are now monitored globally on a routine basis, and their assimilation in global models are becoming well established. In this talk we will reexamine the Alpert et al. (1998) hypothesis using the most recent version of the GEOS-5 Data Assimilation System with assimilation of aerosols. We will

  2. Factors influencing dry season ozone distributions over the tropical South Atlantic

    Science.gov (United States)

    Anderson, B. E.; Gregory, G. L.; Barrick, J. D. W.; Collins, J. E.; Sachse, G. W.; Hudgins, C. H.; Bradshaw, J. D.; Sandholm, S. T.

    1993-01-01

    Airborne measurements of trace gas and aerosol species were obtained in the lower troposphere (less than 5 km) over the western Atlantic Ocean between 13 deg S and 40 deg N during the August/September 1990 NASA Chemical Instrument Test and Evaluation (CITE 3) experiment. The largest background O3 mixing ratios, averaging 35 and 70 ppbv within the mixed layer (ML) and free troposphere (FT; altitudes greater than 2.4 km), respectively, were found over the tropical South Atlantic. Several competing processes were observed to regulate O3 budgets in this region. Within the ML, rapid photochemical destruction produced a diurnal O3 variation of 8 ppbv and an O3/altitude gradient between the surface and 5 km of almost 10 ppbv (O3)/km. ML O3 concentrations were replenished by atmospheric downwelling which occurred at rates of up to and exceeding 1 cm/s. Ozone values within the subsiding FT air were enriched both by long-range transport of O3 produced photochemically within biomass combustion plumes and the downward propagation of dry, upper tropospheric air masses. Overall, the tropospheric O3 column below 3.3 km averaged 13.5 Dobson units (DU) over the South Atlantic region, which is 8-9 DU higher than observed during CITE 3 ferry flights over the northern tropical Atlantic Ocean or measured by ozonesondes over coastal Brazil during the wet season. An examination of simultaneous dew point and combustion tracer (e.g., CO) measurements suggests that the dry subsiding layers and biomass burning layers make approximately equal contributions to the observed O3 enhancement.

  3. Trophic ecology of yellownose skate Zearaja chilensis, a top predator in the south-western Atlantic Ocean.

    Science.gov (United States)

    Belleggia, M; Andrada, N; Paglieri, S; Cortés, F; Massa, A M; Figueroa, D E; Bremec, C

    2016-03-01

    The diet and trophic level (TL ) of the yellownose skate Zearaja chilensis in the south-western Atlantic Ocean (35°-54° S), and how these varied in relation to body size, sex, maturity stage, depth and region were determined by analysis of stomach contents. From 776 specimens analysed, 671 (86·5%) ranging from 180 to 1190 mm total length (LT ) had prey in their stomachs. The diet was dominated by fishes, mainly the notothenioid Patagonotothen ramsayi and the Argentine hake Merluccius hubbsi. The consumption of fishes and crabs increased with increasing predator size, and these preys were more important in the north than in the south. Isopods and other crustaceans were consumed more in the south and their consumption decreased as the size of Z. chilensis increased. The TL of Z. chilensis increased with LT from 4·29 to 4·59 (mean 4·53), confirming their ecological role as a top predator. The small and large size classes exhibited a low diet overlap and the highest spatial segregation, whereas medium and large specimens had higher co-occurrence and dietary overlap indices. A clear distinction in tooth shape was noted between sexes in adult specimens, with males having longer cusps. This sexual heterodonty may be related to reproductive behaviour, increasing the grasping ability of males during courtship, because there were no differences in diet between the sexes. © 2016 The Fisheries Society of the British Isles.

  4. A new species of brooding Psolidae (Echinodermata: Holothuroidea) from deep-sea off Argentina, Southwestern Atlantic Ocean

    Science.gov (United States)

    Martinez, Mariano I.; Penchaszadeh, Pablo E.

    2017-12-01

    This paper describes a new species of Psolus (Holothuroidea, Echinodermata), P. lawrencei sp. nov., (19 specimens) found in the deep sea (308-1398 m) in the Southwestern Atlantic Ocean (SWAO) (around 38°S-54°W) with brooders (up to 3.15 mm) in the tentacles of females and a penis-like genital papilla on males. The presence of dorsal scales, the concave shape of the ossicles with a bridge, the distribution of podia on the dorsal side and the absence of large and conspicuous oral and anal valves are unique for this species. Furthermore, this is the first species of this genus found outside Antarctica that broods between its tentacles. The paper also reviews the reproductive, brooding development and morphological characteristics of P. lawrencei sp. nov. and compares them with those of several members of the family Psolidae. Finally, a possible connectivity between the deep-sea populations in the SWAO and in Antarctica is considered based on the appearance of a similar reproductive pattern in populations found in both areas, which suggests a past or present connection between these regions.

  5. Land Suitability Assessment in the Catchment Area of Four Southwestern Atlantic Coastal Lagoons: Multicriteria and Optimization Modeling

    Science.gov (United States)

    Rodriguez-Gallego, Lorena; Achkar, Marcel; Conde, Daniel

    2012-07-01

    In the present study, a land suitability assessment was conducted in the basin of four Uruguayan coastal lagoons (Southwestern Atlantic) to analyze the productive development while minimizing eutrophication, biodiversity loss and conflicts among different land uses. Suitable land for agriculture, forest, livestock ranching, tourism and conservation sectors were initially established based on a multi-attribute model developed using a geographic information system. Experts were consulted to determine the requirements for each land use sector and the incompatibilities among land use types. The current and potential conflicts among incompatible land use sectors were analyzed by overlapping land suitability maps. We subsequently applied a multi-objective model where land (pixels) with similar suitability was clustered into "land suitability groups", using a two-phase cluster analysis and the Akaike Information Criterion. Finally, a linear programming optimization procedure was applied to allocate land use sectors into land suitable groups, maximizing total suitability and minimizing interference among sectors. Results indicated that current land use overlapped by 4.7 % with suitable land of other incompatible sectors. However, the suitable land of incompatible sectors overlapped in 20.3 % of the study area, indicating a high potential for the occurrence of future conflict. The highest competition was between agriculture and conservation, followed by forest and agriculture. We explored scenarios where livestock ranching and tourism intensified, and found that interference with conservation and agriculture notably increased. This methodology allowed us to analyze current and potential land use conflicts and to contribute to the strategic planning of the study area.

  6. Characterization of "dead-zone" eddies in the tropical Northeast Atlantic Ocean

    OpenAIRE

    Schütte, Florian; Karstensen, Johannes; Krahmann, Gerd; Hauss, Helena; Fiedler, Björn; Brandt, Peter; Visbeck, Martin; Körtzinger, Arne

    2016-01-01

    Localized open-ocean low-oxygen “dead zones” in the eastern tropical North Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic mode-water eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats reveals that “dead-zone” eddies are found in surprisingly high numbers and in a large area from about 4 to 22° N, from the...

  7. New records of the striped cleaner shrimp Lysmata grabhami (Gordon, 1935 from Brazil, Southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    A. D. Kassuga

    Full Text Available Abstract New records for Lysmata grabhami (Gordon, 1935 in Brazilian waters are presented. Four adult individuals from coastal waters off the city of Vitória, Espírito Santo coast and one adult from Trindade Island were collected during scuba diving in depths between 20-40 meters. These two records represent the southernmost published finding of this species in the Atlantic and the record for Vitória, Espirito Santo is the first from Brazilian coastal waters.

  8. Influence of Tropical South Atlantic Sea Surface Temperatures on the Indian Summer monsoon in CMIP5 models

    Science.gov (United States)

    Kucharski, Fred; Joshi, Manish K.

    2017-04-01

    In this study the teleconnection from the tropical south Atlantic to the Indian monsoon has been assessed in observations and in 32 models from the World Climate Research Program (WCRP) Coupled Model Intercomparison Project Phase 5 (CMIP5). All models show that the regression pattern of tropics-wide Atlantic sea surface temperature (SST) anomalies onto the tropical south Atlantic index correlates well with that in observations, even though with varying spatial standard deviations. However, only about half of the 32 models considered show the correct sign of rainfall response over India to a warm anomaly in the south tropical Atlantic, which is a reduction of rainfall. On the other hand, models generally do show large-scale responses broadly consistent with the observations, and the signal over India depends on relatively subtle changes in the response. This response to a tropical south Atlantic warm (cold) anomaly is a low-level quadrupole in streamfunction with an anticyclonic (cyclonic) anomaly over the Arabian Sea and India. This anticyclonic (cyclonic) anomaly leads to a weakening (strengthening) of the Somali jet and low-level divergence (convergence) over India, both inducing a reduction (increase) of Indian rainfall. The models which do not show the correct rainfall response over India also show a response similar to the one indicated above, but with maximum of the anticyclonic (cyclonic) response shifted to the western Pacific. The large-scale Walker circulation adjustment to the tropical south Atlantic SST anomalies is identified as one of the factors which account for the differences in the low-level streamfunction response. Models (and the observations) with the correct sign of the rainfall signal over India show the dominant upper-level convergence (divergence) as response to a warm (cold) tropical south Atlantic in the western Pacific region, whereas models with the wrong sign of the rainfall signal show it predominantly in the central-eastern Pacific

  9. Reef fish structure and distribution in a south-western Atlantic Ocean tropical island.

    Science.gov (United States)

    Pinheiro, H T; Ferreira, C E L; Joyeux, J-C; Santos, R G; Horta, P A

    2011-12-01

    The community structure of the reef fish fauna of Trindade Island, a volcanic oceanic island located 1160 km off the coast of Brazil, is described based on intensive visual censuses. Seventy-six species were encountered in 252 censuses, with mean ± S.E. of 99 ± 3 individuals and 15.7 ± 0.3 species 40 m(-2) transect. The average fish biomass, calculated from length-class estimation, was 22.1 kg 40 m(-2) transect. The species contributing most to biomass were, in decreasing order, Melichthys niger, Cephalopholis fulva, Kyphosus spp., Holocentrus adscensionis, Sparisoma amplum, Sparisoma axillare, Acanthurus bahianus and Epinephelus adscensionis. Carnivorous fishes were the largest trophic group in terms of biomass, followed by omnivores and roving herbivores. The two predominant types of reef habitat, fringing reefs built by coralline algae and rocky reefs made of volcanic boulders, showed significant differences in the biomass and the abundance of the trophic guilds. Within each habitat type, significant differences in species richness, density and biomass were detected among crest, slope and interface zones. Although similar in overall species composition to coastal reefs in Brazil, the fish fauna of Trindade Island shares certain characteristics, such as a high abundance of planktivores, with other Brazilian oceanic islands. Despite comparatively high fish biomass, including the macro-carnivorous species habitually targeted by fisheries, signs of overfishing were evident. These findings highlight the urgency for a conservation initiative for this isolated, unique and vulnerable reef system. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

  10. Capture fishery in northern Todos os Santos Bay, tropical southwestern Atlantic, Brazil

    Directory of Open Access Journals (Sweden)

    Lucy Satiko Hashimoto Soares

    2011-03-01

    Full Text Available Information on marine and estuarine capture fishery activity in northern Todos os Santos Bay, northeastern Brazil, based on daily data collected between September 2003 and June 2005 is presented. Small-scale artisanal fishery in this area includes the use of traditional vessels both nonmotorized and motorized for locomotion, being carried out mainly by canoe or on foot, and involves many different kinds of gear, including gillnet, hook and line, seine nets, and traps. A total of 113 taxa were grouped into 77 resources, including 88 fish, 10 crustaceans, and 15 mollusks. Data on nominal catches of fish, crustaceans and mollusks are presented by month and location. A total of 345.2 tonnes of fishery resources were produced (285.4 tonnes of fish, 39.2 tonnes of fresh invertebrates, and 20.6 tonnes of processed invertebrates. Temporal variation in the fish catch was associated with the life cycle of the species or with the hydrographic conditions. The first-sale value of this catch amounted to around US$ 615,000.00, fishes representing 71.3% of it. A table of the average price of each fishery resource is presented. The results produced in this study may be considered a reference for future monitoring programs of fishery resources in the area.Informações sobre a atividade pesqueira extrativa da região norte da Baía de Todos os Santos, Bahia, nordeste do Brasil são apresentadas, baseadas em coleta diária de dados, realizada entre setembro de 2003 e junho de 2005. Trata-se de uma atividade extrativa artesanal, na qual são utilizadas embarcações tradicionais para o deslocamento ao local da extração. Em cada pescaria foram utilizadas várias artes, tais como rede de espera, linha e anzol, rede de cerco, armadilhas. Foram identificadas 113 categorias taxonômicas de peixes (88, crustáceos (10 e moluscos (15, arranjadas em 77 tipos de pescados comercializados. A produção total no período foi de 345,2 t (285.4 t de peixes, 39,2 t de invertebrados frescos e 20,6 t de invertebrados processados. Variações espaçotemporais da produção total desses pescados podem estar relacionadas à sazonalidade das condições meteorológicas, oceanográficas ou biológicas. A partir do preço da primeira comercialização, foi obtido um valor da primeira venda de R$ 1 279 881,63, sendo 71,3% referentes à produção de peixes. Uma tabela de preço médio de cada recurso pesqueiro é fornecida. Contextualizando os dados pretéritos disponíveis, este trabalho pode ser considerado como uma referência para o futuro monitoramento da pesca na área.

  11. Impact of tropical SST variations on the linear predictability of the atmospheric circulation in the Atlantic/European region

    Directory of Open Access Journals (Sweden)

    H. Feddersen

    2003-06-01

    Full Text Available Seasonal mean values of tropical Sea Surface Temperature (SST and Atlantic/European Mean Sea Level Pressure (MSLP from a 301-year coupled ocean/atmosphere model run are analysed statistically. Relations between the two fields are identified on both interannual and interdecadal timescales. It is shown that tropical SST variability affects Atlantic/European MSLP in winter. In particular, there appears to be a statistically significant relation, between the leading modes of variability, the El Niño/Southern Oscillation (ENSO and the North Atlantic Oscillation (NAO. During cold ENSO (La Niña years the NAO tends to be in its positive phase, while the opposite is the case during warm ENSO (El Niño years, although to a lesser extent. Similar analyses that are presented for gridded observational data, confirm this result, although here tropical Atlantic SST appears to be stronger related to the NAO than tropical Pacific SST. The linear predictability of a model simulated NAO index is estimated by making statistical predictions that are based on model simulated tropical SST. It is shown that the predictive skill is rather insensitive to the length of the training period. On the other hand, the skill score estimate can vary significantly as a result of interdecadal variability in the climate system. These results are important to bear in mind when making statistical seasonal forecasts that are based on observed SST.

  12. Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation

    Science.gov (United States)

    Richter, Ingo; Xie, Shang-Ping; Wittenberg, Andrew T.; Masumoto, Yukio

    2012-03-01

    Most coupled general circulation models (GCMs) perform poorly in the tropical Atlantic in terms of climatological seasonal cycle and interannual variability. The reasons for this poor performance are investigated in a suite of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory (GFDL) coupled GCM. The experiments show that a significant portion of the equatorial SST biases in the model is due to weaker than observed equatorial easterlies during boreal spring. Due to these weak easterlies, the tilt of the equatorial thermocline is reduced, with shoaling in the west and deepening in the east. The erroneously deep thermocline in the east prevents cold tongue formation in the following season despite vigorous upwelling, thus inhibiting the Bjerknes feedback. It is further shown that the surface wind errors are due, in part, to deficient precipitation over equatorial South America and excessive precipitation over equatorial Africa, which already exist in the uncoupled atmospheric GCM. Additional tests indicate that the precipitation biases are highly sensitive to land surface conditions such as albedo and soil moisture. This suggests that improving the representation of land surface processes in GCMs offers a way of improving their performance in the tropical Atlantic. The weaker than observed equatorial easterlies also contribute remotely, via equatorial and coastal Kelvin waves, to the severe warm SST biases along the southwest African coast. However, the strength of the subtropical anticyclone and along-shore winds also play an important role.

  13. Tropical Atlantic biases and their relation to surface wind stress and terrestrial precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Ingo [Research Institute for Global Change, JAMSTEC, Yokohama (Japan); University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); Xie, Shang-Ping [University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States); University of Hawaii at Manoa, Department of Meteorology, Honolulu, HI (United States); Wittenberg, Andrew T. [NOAA/Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States); Masumoto, Yukio [Research Institute for Global Change, JAMSTEC, Yokohama (Japan)

    2012-03-15

    Most coupled general circulation models (GCMs) perform poorly in the tropical Atlantic in terms of climatological seasonal cycle and interannual variability. The reasons for this poor performance are investigated in a suite of sensitivity experiments with the Geophysical Fluid Dynamics Laboratory (GFDL) coupled GCM. The experiments show that a significant portion of the equatorial SST biases in the model is due to weaker than observed equatorial easterlies during boreal spring. Due to these weak easterlies, the tilt of the equatorial thermocline is reduced, with shoaling in the west and deepening in the east. The erroneously deep thermocline in the east prevents cold tongue formation in the following season despite vigorous upwelling, thus inhibiting the Bjerknes feedback. It is further shown that the surface wind errors are due, in part, to deficient precipitation over equatorial South America and excessive precipitation over equatorial Africa, which already exist in the uncoupled atmospheric GCM. Additional tests indicate that the precipitation biases are highly sensitive to land surface conditions such as albedo and soil moisture. This suggests that improving the representation of land surface processes in GCMs offers a way of improving their performance in the tropical Atlantic. The weaker than observed equatorial easterlies also contribute remotely, via equatorial and coastal Kelvin waves, to the severe warm SST biases along the southwest African coast. However, the strength of the subtropical anticyclone and along-shore winds also play an important role. (orig.)

  14. Variability of tropical cyclone rapid intensification in the North Atlantic and its relationship with climate variations

    Science.gov (United States)

    Wang, Chunzai; Wang, Xidong; Weisberg, Robert H.; Black, Michael L.

    2017-12-01

    The paper uses observational data from 1950 to 2014 to investigate rapid intensification (RI) variability of tropical cyclones (TCs) in the North Atlantic and its relationships with large-scale climate variations. RI is defined as a TC intensity increase of at least 15.4 m/s (30 knots) in 24 h. The seasonal RI distribution follows the seasonal TC distribution, with the highest number in September. Although an RI event can occur anywhere over the tropical North Atlantic (TNA), there are three regions of maximum RI occurrence: (1) the western TNA of 12°N-18°N and 60°W-45°W, (2) the Gulf of Mexico and the western Caribbean Sea, and (3) the open ocean southeast and east of Florida. RI events also show a minimum value in the eastern Caribbean Sea north of South America—a place called a hurricane graveyard due to atmospheric divergence and subsidence. On longer time scales, RI displays both interannual and multidecadal variability, but RI does not show a long-term trend due to global warming. The top three climate indices showing high correlations with RI are the June-November ENSO and Atlantic warm pool indices, and the January-March North Atlantic oscillation index. It is found that variabilities of vertical wind shear and TC heat potential are important for TC RI in the hurricane main development region, whereas relative humidity at 500 hPa is the main factor responsible for TC RI in the eastern TNA. However, the large-scale oceanic and atmospheric variables analyzed in this study do not show an important role in TC RI in the Gulf of Mexico and the open ocean southeast and east of Florida. This suggests that other factors such as small-scale changes of oceanic and atmospheric variables or TC internal processes may be responsible for TC RI in these two regions. Additionally, the analyses indicate that large-scale atmospheric and oceanic variables are not critical to TC genesis and formation; however, once a tropical depression forms, large-scale climate

  15. Transport and deposition of the fire biomarker levoglucosan across the tropical North Atlantic Ocean

    Science.gov (United States)

    Schreuder, Laura T.; Hopmans, Ellen C.; Stuut, Jan-Berend W.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2018-04-01

    Biomass burning impacts biogeochemical cycling, vegetation dynamics and climate. However, interactions between fire, climate and vegetation are not well understood and therefore studies have attempted to reconstruct fire and vegetation history under different climatic conditions using sedimentary archives. Here we focus on levoglucosan, a thermal by-product of cellulose generated during biomass burning, and, therefore, a potential fire biomarker in the marine sedimentary archive. However, before levoglucosan can be applied as a biomass burning proxy in marine sediments, there is a need for studies on how levoglucosan is transported to the marine environment, how it is reflecting biomass burning on continents, as well as the fate of levoglucosan in the marine water column and during deposition in marine sediments. Here we present analyses of levoglucosan, using an improved Ultra High Pressure Liquid Chromatography-Electro Spray Ionization/High Resolution Mass Spectrometry (UHPLC-ESI/HRMS) method, in atmospheric particles, in particulate matter settling through the water column and in marine surface sediments on a longitudinal transect crossing the tropical North Atlantic Ocean at 12°N. Levoglucosan was detected in the atmosphere, although in low concentration, possibly due to the sampled particle size, the source area of the aerosols, or the short time interval of sampling by which large burning events may have been missed. In sinking particles in the tropical North Atlantic Ocean we find that levoglucosan deposition is influenced by a mineral ballast effect associated with marine biogenic particles, and that levoglucosan is not transported in association with mineral dust particles. Highest levoglucosan concentrations and seasonal differences in sinking particles were found close to continents and low concentrations and seasonal differences were found in the open ocean. Close to Africa, levoglucosan concentration is higher during winter, reflecting seasonal

  16. Revisiting tropical instability wave variability in the Atlantic ocean using SODA reanalysis

    Science.gov (United States)

    de Decco, Hatsue Takanaca; Torres Junior, Audalio Rebelo; Pezzi, Luciano Ponzi; Landau, Luiz

    2018-03-01

    The spatial and temporal variability of energy exchange in Tropical Instability Waves (TIWs) in the Atlantic Ocean were investigated. A spectral analysis was used to filter the 5-day mean results from Simple Ocean Data Assimilation (SODA) reanalysis spanning from 1958 to 2008. TIWs were filtered over periods of 15 to 60 days and between wavelengths of 4 and 20 longitude degrees. The main approach of this study was the use of bidirectionally filtered TIW time series as the perturbation fields, and the difference in these time series from the SODA total results was considered to be the basic state for energetics analysis. The main result was that the annual cycle (period of 360 days) was the main source of variability of the waves, and the semi-annual cycle (period of 180 days) was a secondary variation, which indicated that TIWs occurred throughout the year but with intensity that varies seasonally. In SODA, barotropic instability acts as the mechanism that feeds and extracts energy to/from TIWs at equatorial Atlantic. Baroclinic instability is the main mechanism that extracts energy from TIWs to the equatorial circulation north of the Equator. All TIW patterns of variability were observed western of 10° W. The present study reveals new evidences regarding TIW variability and suggests that future investigations should include a detailed description of TIW dynamics as part of Atlantic Ocean equatorial circulation.

  17. How Well Do Global Climate Models Simulate the Variability of Atlantic Tropical Cyclones Associated with ENSO?

    Science.gov (United States)

    Wang, Hui; Long, Lindsey; Kumar, Arun; Wang, Wanqiu; Schemm, Jae-Kyung E.; Zhao, Ming; Vecchi, Gabriel A.; LaRow, Timorhy E.; Lim, Young-Kwon; Schubert, Siegfried D.; hide

    2013-01-01

    The variability of Atlantic tropical cyclones (TCs) associated with El Nino-Southern Oscillation (ENSO) in model simulations is assessed and compared with observations. The model experiments are 28-yr simulations forced with the observed sea surface temperature from 1982 to 2009. The simulations were coordinated by the U.S. CLIVAR Hurricane Working Group and conducted with five global climate models (GCMs) with a total of 16 ensemble members. The model performance is evaluated based on both individual model ensemble means and multi-model ensemble mean. The latter has the highest anomaly correlation (0.86) for the interannual variability of TCs. Previous observational studies show a strong association between ENSO and Atlantic TC activity, as well as distinctions in the TC activities during eastern Pacific (EP) and central Pacific (CP) El Nino events. The analysis of track density and TC origin indicates that each model has different mean biases. Overall, the GCMs simulate the variability of Atlantic TCs well with weaker activity during EP El Nino and stronger activity during La Nina. For CP El Nino, there is a slight increase in the number of TCs as compared with EP El Nino. However, the spatial distribution of track density and TC origin is less consistent among the models. Particularly, there is no indication of increasing TC activity over the U.S. southeast coastal region as in observations. The difference between the models and observations is likely due to the bias of vertical wind shear in response to the shift of tropical heating associated with CP El Nino, as well as the model bias in the mean circulation.

  18. Iron limitation of microbial phosphorus acquisition in the tropical North Atlantic

    Science.gov (United States)

    Browning, Thomas; Achterberg, Eric; Yong, Jaw Chuen; Rapp, Insa; Utermann, Caroline; Engel, Anja; Moore, Mark

    2017-04-01

    Growth-limitation of marine phytoplankton by fixed nitrogen (N) has been demonstrated for most of the low-latitude oceans; however, in the (sub)tropical North Atlantic enhanced N2 fixation leads to secondary/(co-)limitation by phosphorus (P). The dissolved organic P pool is rarely fully depleted in the modern ocean and potentially represents a substantial additional P source. Microbes can use a variety of alkaline phosphatase enzymes to access P from a major fraction of this pool. In contrast to the relatively well studied PhoA family of alkaline phosphatases that utilize zinc (Zn) as a cofactor, the recent discovery of iron (Fe) as a cofactor in the more widespread PhoX[1] and PhoD[2] enzymes imply potential for a complex, biochemically-dependant interplay between oceanic Zn, Fe and P cycles. Here we demonstrate enhanced natural community alkaline phosphatase activity (APA) following Fe amendment within the low Zn and moderately low Fe western tropical North Atlantic. In contrast, beneath the Saharan dust plume in the Eastern Atlantic no APA response to trace metal addition was observed. This is the first demonstration of intermittent Fe limitation of microbial P acquisition, providing an additional facet in the argument for Fe control of the coupling between oceanic N and P cycles. 1. Yong, S. C. et al. A complex iron-calcium cofactor catalyzing phosphotransfer chemistry. Science 345, 1170-3 (2014). 2. Rodriguez, F. et al. Crystal structure of the Bacillus subtilis phosphodiesterase PhoD reveals an iron and calcium-containing active site. J. Biol. Chem. 289, 30889-30899 (2014).

  19. Variability and trends of carbon parameters at a time series in the eastern tropical Atlantic

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    Nathalie Lefèvre

    2016-05-01

    Full Text Available Hourly fCO2 is recorded at a time series at the PIRATA buoy located at 6°S 10°W in the eastern tropical Atlantic since June 2006. This site is located south and west of the seasonal Atlantic cold tongue and is affected by its propagation from June to September. Using an alkalinity–salinity relationship determined for the eastern tropical Atlantic and the observed fCO2, pH and the inorganic carbon concentration are calculated. The time series is investigated to explore the intraseasonal, seasonal and interannual timescales for these parameters, and to detect any long-term trends. At intraseasonal timescales, fCO2 and pH are strongly correlated. On seasonal timescales, the correlation still holds between fCO2 and pH and their variations are in agreement with those of sea surface salinity. At interannual timescales, some important differences appear in 2011–2012: lower fCO2 and fluxes are observed from September to December 2011 and are explained by higher advection of salty waters at the mooring, in agreement with the wind. In early 2012, the anomaly is still present and associated with lower sea surface temperatures. No significant long-term trend is detected over the period 2006–2013 on CO2 and any other physical parameter. However, as atmospheric fCO2 is increasing over time, the outgassing of CO2 is reduced over the period 2006–2013 as the flux is mainly controlled by the difference of fCO2 between the ocean and the atmosphere. A longer time series is required to determine if any significant trend exists in this region.

  20. Population genetic structure of Guiana dolphin (Sotalia guianensis from the southwestern Atlantic coast of Brazil.

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    Juliana Ywasaki Lima

    Full Text Available Sotalia guianensis is a small dolphin that is vulnerable to anthropogenic impacts. Along the Brazilian Atlantic coast, this species is threatened with extinction. A prioritized action plan for conservation strategies relies on increased knowledge of the population. The scarcity of studies about genetic diversity and assessments of population structure for this animal have precluded effective action in the region. Here, we assessed, for the first time, the genetic differentiation at 14 microsatellite loci in 90 S. guianensis specimens stranded on the southeastern Atlantic coast of the State of Espírito Santo, Brazil. We estimated population parameters and structure, measured the significance of global gametic disequilibrium and the intensity of non-random multiallelic interallelic associations and constructed a provisional synteny map using Bos taurus, the closest terrestrial mammal with a reference genome available. All microsatellite loci were polymorphic, with at least three and a maximum of ten alleles each. Allele frequencies ranged from 0.01 to 0.97. Observed heterozygosity ranged from 0.061 to 0.701. The mean inbreeding coefficient was 0.103. Three loci were in Hardy-Weinberg disequilibrium even when missing genotypes were inferred. Although 77 of the 91 possible two-locus associations were in global gametic equilibrium, we unveiled 13 statistically significant, sign-based, non-random multiallelic interallelic associations in 10 two-locus combinations with either coupling (D' values ranging from 0.782 to 0.353 or repulsion (D' values -0.517 to -1.000 forces. Most of the interallelic associations did not involve the major alleles. Thus, for either physically or non-physically linked loci, measuring the intensity of non-random interallelic associations is important for defining the evolutionary forces at equilibrium. We uncovered a small degree of genetic differentiation (FST = 0.010; P-value = 0.463 with a hierarchical clustering into one

  1. Population genetic structure of Guiana dolphin (Sotalia guianensis) from the southwestern Atlantic coast of Brazil.

    Science.gov (United States)

    Ywasaki Lima, Juliana; Machado, Filipe Brum; Farro, Ana Paula Cazerta; Barbosa, Lupércio de Araújo; da Silveira, Leonardo Serafim; Medina-Acosta, Enrique

    2017-01-01

    Sotalia guianensis is a small dolphin that is vulnerable to anthropogenic impacts. Along the Brazilian Atlantic coast, this species is threatened with extinction. A prioritized action plan for conservation strategies relies on increased knowledge of the population. The scarcity of studies about genetic diversity and assessments of population structure for this animal have precluded effective action in the region. Here, we assessed, for the first time, the genetic differentiation at 14 microsatellite loci in 90 S. guianensis specimens stranded on the southeastern Atlantic coast of the State of Espírito Santo, Brazil. We estimated population parameters and structure, measured the significance of global gametic disequilibrium and the intensity of non-random multiallelic interallelic associations and constructed a provisional synteny map using Bos taurus, the closest terrestrial mammal with a reference genome available. All microsatellite loci were polymorphic, with at least three and a maximum of ten alleles each. Allele frequencies ranged from 0.01 to 0.97. Observed heterozygosity ranged from 0.061 to 0.701. The mean inbreeding coefficient was 0.103. Three loci were in Hardy-Weinberg disequilibrium even when missing genotypes were inferred. Although 77 of the 91 possible two-locus associations were in global gametic equilibrium, we unveiled 13 statistically significant, sign-based, non-random multiallelic interallelic associations in 10 two-locus combinations with either coupling (D' values ranging from 0.782 to 0.353) or repulsion (D' values -0.517 to -1.000) forces. Most of the interallelic associations did not involve the major alleles. Thus, for either physically or non-physically linked loci, measuring the intensity of non-random interallelic associations is important for defining the evolutionary forces at equilibrium. We uncovered a small degree of genetic differentiation (FST = 0.010; P-value = 0.463) with a hierarchical clustering into one segment

  2. Four-year monthly sediment deposition on turbid southwestern Atlantic coral reefs, with a comparison of benthic assemblages

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    Clovis Barreira e Castro

    2012-03-01

    Full Text Available High sedimentation is often related to stress in coral reef communities. Most southwestern Atlantic reefs are characterized by high sedimentation. However, there are no temporal series of sediment deposition rates. We evaluated sediment deposition, the sediment carbonate composition and coral and zoanthid covers on six reefs in Brazil over four-years. Sediment deposition rates varied from near zero to 233 mg cm-2 day-1, with peaks between August and December, and yearly averages ranging from nine to 104 mg cm-2 day-1. Deposition rates presented site-specific correlations with wind, indicating that resuspension must be a major factor. The presence of carbonates varied from 38% to 90%, with two sites showing seasonal differences. Benthic communities were fairly similar among sites, but the analyses suggested particular frequencies at each site. There was no significant correlation between sediment and benthic communities. However, Palythoa caribaeorum usually occur in high sediment deposition areas. Our results did not corroborate previous data that suggested that a 10 mg cm-2 day-1 would be a "critical limit for coral survival". Some coral reefs may be associated with high sedimentation environments including carbonatic fractions, but which does not per se hinder the development of southwestern Atlantic coral reef communities.A sedimentação é freqüentemente relacionada a estresse em recifes de coral. Os recifes do Atlântico sul ocidental possuem grande sedimentação, entretanto carecem de séries temporais das taxas de deposição de sedimento. Foram avaliadas estas taxas e a composição carbonática do sedimento, além da cobertura de corais e zoantídeos em seis recifes brasileiros durante quatro anos consecutivos. A deposição variou de zero a 233 mg cm-2 dia-1, com picos entre agosto e dezembro e médias anuais variando de nove a 104 mg cm-2 dia-1. As taxas de deposição apresentaram correlação com o vento, indicando que a

  3. Net sea-air CO2 fluxes and modelled pCO2 in the southwestern subtropical Atlantic continental shelf during spring 2010 and summer 2011

    Science.gov (United States)

    Ito, Rosane Gonçalves; Garcia, Carlos Alberto Eiras; Tavano, Virginia Maria

    2016-05-01

    Sea-air CO2 fluxes over continental shelves vary substantially in time on both seasonal and sub-seasonal scales, driven primarily by variations in surface pCO2 due to several oceanic mechanisms. Furthermore, coastal zones have not been appropriately considered in global estimates of sea-air CO2 fluxes, despite their importance to ecology and to productivity. In this work, we aimed to improve our understanding of the role played by shelf waters in controlling sea-air CO2 fluxes by investigating the southwestern Atlantic Ocean (21-35°S) region, where physical, chemical and biological measurements were made on board the Brazilian R. V. Cruzeiro do Sul during late spring 2010 and early summer 2011. Features such as discharge from the La Plata River, intrusions of tropical waters on the outer shelf due to meandering and flow instabilities of the Brazil Current, and coastal upwelling in the Santa Marta Grande Cape and São Tomé Cape were detected by both in situ measurements and ocean colour and thermal satellite imagery. Overall, shelf waters in the study area were a source of CO2 to the atmosphere, with an average of 1.2 mmol CO2 m-2 day-1 for the late spring and 11.2 mmol CO2 m-2 day-1 for the early summer cruises. The spatial variability in ocean pCO2 was associated with surface ocean properties (temperature, salinity and chlorophyll-a concentration) in both the slope and shelf waters. Empirical algorithms for predicting temperature-normalized surface ocean pCO2 as a function of surface ocean properties were shown to perform well in both shelf and slope waters, except (a) within cyclonic eddies produced by baroclinic instability of the Brazil Current as detected by satellite SST imagery and (b) in coastal upwelling regions. In these regions, surface ocean pCO2 values were higher as a result of upwelled CO2-enriched subsurface waters. Finally, a pCO2 algorithm based on both sea surface temperature and surface chlorophyll-a was developed that enabled the spatial

  4. Land suitability assessment in the catchment area of four Southwestern Atlantic coastal lagoons: multicriteria and optimization modeling.

    Science.gov (United States)

    Rodriguez-Gallego, Lorena; Achkar, Marcel; Conde, Daniel

    2012-07-01

    In the present study, a land suitability assessment was conducted in the basin of four Uruguayan coastal lagoons (Southwestern Atlantic) to analyze the productive development while minimizing eutrophication, biodiversity loss and conflicts among different land uses. Suitable land for agriculture, forest, livestock ranching, tourism and conservation sectors were initially established based on a multi-attribute model developed using a geographic information system. Experts were consulted to determine the requirements for each land use sector and the incompatibilities among land use types. The current and potential conflicts among incompatible land use sectors were analyzed by overlapping land suitability maps. We subsequently applied a multi-objective model where land (pixels) with similar suitability was clustered into "land suitability groups", using a two-phase cluster analysis and the Akaike Information Criterion. Finally, a linear programming optimization procedure was applied to allocate land use sectors into land suitable groups, maximizing total suitability and minimizing interference among sectors. Results indicated that current land use overlapped by 4.7 % with suitable land of other incompatible sectors. However, the suitable land of incompatible sectors overlapped in 20.3 % of the study area, indicating a high potential for the occurrence of future conflict. The highest competition was between agriculture and conservation, followed by forest and agriculture. We explored scenarios where livestock ranching and tourism intensified, and found that interference with conservation and agriculture notably increased. This methodology allowed us to analyze current and potential land use conflicts and to contribute to the strategic planning of the study area.

  5. Ten-year variations in population structure of pink-shrimp in a southwestern Atlantic Bay affected by highway construction

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    Felipe Freitas Jr

    2011-12-01

    Full Text Available OBJECTIVES: Population structures of Farfantepenaeus brasiliensis and F. paulensis, consisting mainly of juveniles, were evaluated during the construction of an expressway along a mangrove area. Estuarine regions in southern Brazil function as sites for reproduction, nursery and growth of a variety of organisms, including two of the most important species of shrimp for fisheries in the southwestern Atlantic. Shrimps were collected in Saco dos Limões creek, Baía-Sul, Florianópolis, State of Santa Catarina, four times a year, by day and night, between 1997 and 2006. Fluctuations in the abundances of shrimp appear to be related to their life cycles, with largest abundances in Summer and Spring, rather than to impacts promoted by dredging activities during the expressway construction.OBJETIVOS: A estrutura populacional de Farfantepenaeus brasiliensis e F. paulensis, consistindo principalmente de juvenis, foi avaliada durante a construção de uma via expressa ao longo de uma área de manguezais. Regiões estuarinas do sul do Brasil funcionam como locais de reprodução, berçários e de crescimento de uma variedade de organismos, incluindo duas das mais importantes espécies de camarões comerciais do Atlântico Sul Ocidental. Camarões foram coletados no Saco dos Limões, Baía Sul, Florianópolis, Estado de Santa Catarina, trimestralmente, de dia e de noite, entre 1997 e 2006. Flutuações em abundâncias de camarões podem estar relacionados aos seus ciclos de vida, com as maiores abundâncias no verão e primavera, ao invés de impactos promovidos pelas atividades de dragagem durante a construção da via expressa.

  6. Degree of simulated suppression of Atlantic tropical cyclones modulated by flavour of El Niño

    Science.gov (United States)

    Patricola, Christina M.; Chang, Ping; Saravanan, R.

    2016-02-01

    El Niño/Southern Oscillation, the dominant mode of interannual climate variability, strongly influences tropical cyclone activity. During canonical El Niño, the warm phase, Atlantic tropical cyclones are suppressed. However, the past decades have witnessed different El Niño characteristics, ranging from warming over the east Pacific cold tongue in canonical events to warming near the warm pool, known as warm pool El Niño or central Pacific El Niño. Global climate models project possible future increases in intensity of warm pool El Niño. Here we use a climate model at a resolution sufficient to explicitly simulate tropical cyclones to investigate how these flavours of El Niño may affect such cyclones. We show that Atlantic tropical cyclones are suppressed regardless of El Niño type. For the warmest 10% of each El Niño flavour, warm pool El Niño is substantially less effective at suppressing Atlantic tropical cyclones than cold tongue El Niño. However, for the same absolute warming intensity, the opposite is true. This is because less warming is required near the warm pool to satisfy the sea surface temperature threshold for deep convection, which leads to tropical cyclone suppression through vertical wind shear enhancements. We conclude that an understanding of future changes in not only location, but also intensity and frequency, of El Niño is important for forecasts and projections of Atlantic tropical cyclone activity.

  7. Paleo-environmental effects of the mid-pleistocene transition in the tropical Atlantic and equatorial Africa

    NARCIS (Netherlands)

    Schefuss, E.

    2003-01-01

    This thesis describes the environmental changes in the eastern tropical Atlantic and equatorial Africa during the Mid-Pleistocene Transition (MPT) as revealed by analyses of lipid biomarkers and their stable carbon isotope compositions. The MPT was the start of the Late Pleistocene ice ages, with

  8. Palaemon vicinus spec. nov. (Crustacea: Decapoda: Palaemonidae), a new species of caridean shrimp from the tropical eastern Atlantic

    NARCIS (Netherlands)

    Ashelby, C.W.

    2009-01-01

    A new species of Palaemon, P. vicinus spec. nov., is described from the tropical eastern Atlantic. The new species is very close to P. elegans Rathke, 1837, under which name it was previously recorded from West Africa. Palaemon vicinus spec. nov. is easily separated from P. elegans by possessing a

  9. Characterization of "dead-zone" eddies in the eastern tropical North Atlantic

    Science.gov (United States)

    Schütte, Florian; Karstensen, Johannes; Krahmann, Gerd; Hauss, Helena; Fiedler, Björn; Brandt, Peter; Visbeck, Martin; Körtzinger, Arne

    2016-10-01

    Localized open-ocean low-oxygen "dead zones" in the eastern tropical North Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic mode-water eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats reveals that "dead-zone" eddies are found in surprisingly high numbers and in a large area from about 4 to 22° N, from the shelf at the eastern boundary to 38° W. In total, 173 profiles with oxygen concentrations below the minimum background concentration of 40 µmol kg-1 could be associated with 27 independent eddies (10 CEs; 17 ACMEs) over a period of 10 years. Lowest oxygen concentrations in CEs are less than 10 µmol kg-1 while in ACMEs even suboxic (ocean. Here water mass properties and satellite eddy tracking both point to an eddy generation near the eastern boundary. In contrast, the oxygen-depleted eddies south of 12° N carry weak hydrographic anomalies in their cores and seem to be generated in the open ocean away from the boundary. In both regions a decrease in oxygen from east to west is identified supporting the en-route creation of the low-oxygen core through a combination of high productivity in the eddy surface waters and an isolation of the eddy cores with respect to lateral oxygen supply. Indeed, eddies of both types feature a cold sea surface temperature anomaly and enhanced chlorophyll concentrations in their center. The low-oxygen core depth in the eddies aligns with the depth of the shallow oxygen minimum zone of the eastern tropical North Atlantic. Averaged over the whole area an oxygen reduction of 7 µmol kg-1 in the depth range of 50 to 150 m (peak reduction is 16 µmol kg-1 at 100 m depth) can be associated with the dispersion of the eddies. Thus the locally increased oxygen consumption within the eddy cores enhances the total oxygen consumption in the open eastern tropical North

  10. Coccolithophore ecology in the tropical and subtropical Atlantic Ocean: New perspectives from the Atlantic meridional transect (AMT) programme

    Science.gov (United States)

    Poulton, Alex J.; Holligan, Patrick M.; Charalampopoulou, Anastasia; Adey, Tim R.

    2017-11-01

    Coccolithophore species composition was determined in 199 samples collected from the upper 300 m of the Atlantic Ocean, spanning temperate, tropical and subtropical waters in both hemispheres during four Atlantic Meridional Transect (AMT) cruises over the period 2003-2005. Of the 171 taxa observed, 140 consistently represented column, horizontally across hydrographic provinces (subtropical gyres, equatorial waters, temperate waters), and temporally between cruises. Sharper gradients of statistical dissimilarity in species composition occurred vertically over a few tens of metres than horizontally over hundreds of kilometres. Three floral groups were identified from analysis of the depth of normalised abundance maxima in the subtropical gyres and equatorial waters: the upper euphotic zone (UEZ, >10% surface irradiance); the lower euphotic zone (LEZ, 10-1% surface irradiance); and the sub-euphotic zone (SEZ, conditions between the LEZ and temperate waters. The SEZ is below the depth where light is thought to be sufficient to support photosynthesis, suggesting that deep-dwelling species such as Florisphaera profunda and Gladiolithus spp. may be mixotrophic or phagotrophic, although conclusive proof will need to be gained experimentally. Mixotrophy could also be an important nutritional strategy for species abundant (Umbellosphaera spp., holococcolithophores) in the UEZ where inorganic nutrient concentrations are depleted and limiting to growth, although other nutritional strategies, such as the use of organic nutrients, are also possible. Statistical differences were also found in the species composition between the different cruises, with high levels of similarity for similar timed cruises (May or September-October). Few individual taxa showed significant variability in abundance over the time-span of sampling, except species such as E. huxleyi and G. ericsonii at higher latitudes. In subtropical and equatorial waters, high levels of species richness and low levels

  11. Sensitivity of tropical cyclones to resolution, convection scheme and ocean flux parameterization over Eastern Tropical Pacific and Tropical North Atlantic Oceans in the RegCM4 model

    Science.gov (United States)

    Fuentes-Franco, Ramón; Giorgi, Filippo; Coppola, Erika; Zimmermann, Klaus

    2017-07-01

    The sensitivity of simulated tropical cyclones (TCs) to resolution, convection scheme and ocean surface flux parameterization is investigated with a regional climate model (RegCM4) over the CORDEX Central America domain, including the Tropical North Atlantic (TNA) and Eastern Tropical Pacific (ETP) basins. Simulations for the TC seasons of the ten-year period (1989-1998) driven by ERA-Interim reanalysis fields are completed using 50 and 25 km grid spacing, two convection schemes (Emanuel, Em; and Kain-Fritsch, KF) and two ocean surface flux representations, a Monin-Obukhov scheme available in the BATS land surface package (Dickinson et al. 1993), and the scheme of Zeng et al. (J Clim 11(10):2628-2644, 1998). The model performance is assessed against observed TC characteristics for the simulation period. In general, different sensitivities are found over the two basins investigated. The simulations using the KF scheme show higher TC density, longer TC duration (up to 15 days) and stronger peak winds (>50 ms-1) than those using Em (<40 ms-1). All simulations show a better spatial representation of simulated TC density and interannual variability over the TNA than over the ETP. The 25 km resolution simulations show greater TC density, duration and intensity compared to the 50 km resolution ones, especially over the ETP basin, and generally more in line with observations. Simulated TCs show a strong sensitivity to ocean fluxes, especially over the TNA basin, with the Monin-Obukhov scheme leading to an overestimate of the TC number, and the Zeng scheme being closer to observations. All simulations capture the density of cyclones during active TC seasons over the TNA, however, without data assimilation, the tracks of individual events do not match closely the corresponding observed ones. Overall, the best model performance is obtained when using the KF and Zeng schemes at 25 km grid spacing.

  12. Variability of Carbon and Water Fluxes Following Climate Extremes over a Tropical Forest in Southwestern Amazonia

    Science.gov (United States)

    Zeri, Marcelo; Sá, Leonardo D. A.; Manzi, Antônio O.; Araújo, Alessandro C.; Aguiar, Renata G.; von Randow, Celso; Sampaio, Gilvan; Cardoso, Fernando L.; Nobre, Carlos A.

    2014-01-01

    The carbon and water cycles for a southwestern Amazonian forest site were investigated using the longest time series of fluxes of CO2 and water vapor ever reported for this site. The period from 2004 to 2010 included two severe droughts (2005 and 2010) and a flooding year (2009). The effects of such climate extremes were detected in annual sums of fluxes as well as in other components of the carbon and water cycles, such as gross primary production and water use efficiency. Gap-filling and flux-partitioning were applied in order to fill gaps due to missing data, and errors analysis made it possible to infer the uncertainty on the carbon balance. Overall, the site was found to have a net carbon uptake of ≈5 t C ha−1 year−1, but the effects of the drought of 2005 were still noticed in 2006, when the climate disturbance caused the site to become a net source of carbon to the atmosphere. Different regions of the Amazon forest might respond differently to climate extremes due to differences in dry season length, annual precipitation, species compositions, albedo and soil type. Longer time series of fluxes measured over several locations are required to better characterize the effects of climate anomalies on the carbon and water balances for the whole Amazon region. Such valuable datasets can also be used to calibrate biogeochemical models and infer on future scenarios of the Amazon forest carbon balance under the influence of climate change. PMID:24558378

  13. Variability of carbon and water fluxes following climate extremes over a tropical forest in southwestern Amazonia.

    Directory of Open Access Journals (Sweden)

    Marcelo Zeri

    Full Text Available The carbon and water cycles for a southwestern Amazonian forest site were investigated using the longest time series of fluxes of CO2 and water vapor ever reported for this site. The period from 2004 to 2010 included two severe droughts (2005 and 2010 and a flooding year (2009. The effects of such climate extremes were detected in annual sums of fluxes as well as in other components of the carbon and water cycles, such as gross primary production and water use efficiency. Gap-filling and flux-partitioning were applied in order to fill gaps due to missing data, and errors analysis made it possible to infer the uncertainty on the carbon balance. Overall, the site was found to have a net carbon uptake of ≈5 t C ha(-1 year(-1, but the effects of the drought of 2005 were still noticed in 2006, when the climate disturbance caused the site to become a net source of carbon to the atmosphere. Different regions of the Amazon forest might respond differently to climate extremes due to differences in dry season length, annual precipitation, species compositions, albedo and soil type. Longer time series of fluxes measured over several locations are required to better characterize the effects of climate anomalies on the carbon and water balances for the whole Amazon region. Such valuable datasets can also be used to calibrate biogeochemical models and infer on future scenarios of the Amazon forest carbon balance under the influence of climate change.

  14. Luxury uptake of aerosol iron by Trichodesmium in the western tropical North Atlantic

    Science.gov (United States)

    Chen, Ying; Tovar-Sanchez, Antonio; Siefert, Ronald L.; Sañudo-Wilhelmy, Sergio A.; Zhuang, Guoshun

    2011-09-01

    Dust transported from North Africa carries micronutrient iron (Fe) to the western tropical North Atlantic (WTNA) which may significantly influence the metabolism of the N2-fixing cyanobacteria, Trichodesmium. For the first time, we conducted shipboard incubation experiments using freshly collected aerosol, seawater, and Trichodesmium colonies. Trichodesmium assimilated significant amount of aerosol Fe up to 14 times higher than the control. The uptake amount increased proportionally to the P: Fe ratio that Trichodesmium initially contained and to the aerosol Fe added and leached to the incubation solution. Trichodesmium assimilated more aerosol Fe than needed for its maximum growth (0.14 d-1) demonstrating a high capacity of luxury uptake of Fe from the dust.

  15. Effects of Atlantic warm pool variability over climate of South America tropical transition zone

    Science.gov (United States)

    Ricaurte Villota, Constanza; Romero-Rodríguez, Deisy; Andrés Ordoñez-Zuñiga, Silvio; Murcia-Riaño, Magnolia; Coca-Domínguez, Oswaldo

    2016-04-01

    Colombia is located in the northwestern corner of South America in a climatically complex region due to the influence processes modulators of climate both the Pacific and Atlantic region, becoming in a transition zone between phenomena of northern and southern hemisphere. Variations in the climatic conditions of this region, especially rainfall, have been attributed to the influence of the El Nino Southern Oscillation (ENSO), but little is known about the interaction within Atlantic Ocean and specifically Caribbean Sea with the environmental conditions of this region. In this work We studied the influence of the Atlantic Warm Pool (AWP) on the Colombian Caribbean (CC) climate using data of Sea Surface Temperature (SST) between 1900 - 2014 from ERSST V4, compared with in situ data SIMAC (National System for Coral Reef Monitoring in Colombia - INVEMAR), rainfall between 1953-2013 of meteorological stations located at main airports in the Colombian Caribbean zone, administered by IDEAM, and winds data between 2003 - 2014 from WindSat sensor. The parameters analyzed showed spatial differences throughout the study area. SST anomalies, representing the variability of the AWP, showed to be associated with Multidecadal Atlantic Oscillation (AMO) and with the index of sea surface temperature of the North-tropical Atlantic (NTA), the variations was on 3 to 5 years on the ENSO scale and of approximately 11 years possibly related to solar cycles. Rainfall anomalies in the central and northern CC respond to changes in SST, while in the south zone these are not fully engage and show a high relationship with the ENSO. Finally, the winds also respond to changes in SST and showed a signal approximately 90 days possibly related to the Madden-Julian Oscillation, whose intensity depends on the CC region being analyzed. The results confirm that region is a transition zone in which operate several forcing, the variability of climate conditions is difficult to attribute only one, as ENSO

  16. Property changes of deep and bottom waters in the Western Tropical Atlantic

    Science.gov (United States)

    Herrford, Josefine; Brandt, Peter; Zenk, Walter

    2017-06-01

    The flow of North Atlantic Deep Water (NADW) and Antarctic Bottom Water (AABW) contributes to the Atlantic meridional overturning circulation. Changes in the associated water mass formation might impact the deep ocean's capacity to take up anthropogenic CO2 while a warming of the deep ocean significantly contributes to global sea level rise. Here we compile historic and recent shipboard measurements of hydrography and velocity to provide a comprehensive view of water mass distribution, pathways, along-path transformation and long-term temperature changes of NADW and AABW in the western South and Equatorial Atlantic. We confirm previous results which show that the northwest corner of the Brazil Basin represents a splitting point for the southward/northward flow of NADW/AABW. The available measurements sample water mass transformation along the two major routes for deep and bottom waters in the tropical to South Atlantic - along the deep western boundary and eastward, parallel to the equator - as well as the hot-spots of extensive mixing. We find lower NADW and lighter AABW to form a highly interactive transition layer in the northern Brazil Basin. The AABW north of 5°S is relatively homogeneous with only lighter AABW being able to pass through the Equatorial Channel (EQCH) into the North Atlantic. Spanning a period of 26 years, our data also allow an estimation of long-term temperature trends in abyssal waters. We find a warming of 2.5±0.7•10-3 °C yr-1 of the waters in the northern Brazil Basin at temperatures colder than 0.6 °C throughout the period 1989-2014 and can relate this warming to a thinning of the dense AABW layer. Whereas isopycnal heave is the dominant effect which defines the vertical distribution of temperature trends on isobars, we also find temperature changes on isopycnals in the lower NADW and AABW layers. There temperatures on isopycnals exhibit decadal variations with warming in the 1990s and cooling in the 2000s - the contributions to the

  17. Nutrients and carbon fluxes in the estuaries of major rivers flowing into the tropical Atlantic

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    Moacyr Cunha De Araujo

    2014-05-01

    Full Text Available Knowledge of the seasonal variability of river discharge and the concentration of nutrients in the estuary waters of large rivers flowing into the tropical Atlantic contributes to a better understanding of the biogeochemical processes that occur in adjacent coastal and ocean systems. The monthly averaged variations of the physical and biogeochemical contributions of the Orinoco, Amazon, São Francisco, Paraíba do Sul (South America, Volta, Niger and Congo (Africa Rivers are estimated from models or observations. The results indicate that these rivers deliver approximately 0.1 Pg C yr-1 in its dissolved organic (DOC 0.046 Pg C yr-1 and inorganic (DIC 0.053 Pg C yr-1 forms combined. These values represent 27.3% of the global DOC and 13.2% of the global DIC delivered by rivers into the world’s oceans. Estimations of the air-sea CO2 fluxes indicate a slightly higher atmospheric liberation for the African systems compared with the South American estuaries (+10.67 mmol m-2 day-1 and +5.48 mmol m-2 day-1, respectively. During the high river discharge periods, the fluxes remained positive in all of the analyzed systems (average +128 mmol m-2 day-1, except at the mouth of the Orinoco River, which continued to act as a sink for CO2. During the periods of low river discharges, the mean CO2 efflux decreased to +5.29 mmol m-2 day-1. The updated and detailed review presented here contributes to the accurate quantification of CO2 input into the atmosphere and to ongoing studies on the oceanic modeling of biogeochemical cycles in the tropical Atlantic.

  18. Tropical Peat and Peatland Development in the Floodplains of the Greater Pamba Basin, South-Western India during the Holocene.

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    Navnith K P Kumaran

    Full Text Available Holocene sequences in the humid tropical region of Kerala, South-western (SW India have preserved abundance of organic-rich sediments in the form of peat and its rapid development in a narrow time frame towards Middle Holocene has been found to be significant. The sub-coastal areas and flood plains of the Greater Pamba Basin have provided palaeorecords of peat indicating that the deposits are essentially formed within freshwater. The combination of factors like stabilized sea level and its subsequent fall since the Middle Holocene, topographic relief and climatic conditions led to rapid peat accumulation across the coastal lowlands. The high rainfall and massive floods coupled with a rising sea level must have inundated > 75% of the coastal plain land converting it into a veritable lagoon-lake system that eventually led to abrupt termination of the forest ecosystem and also converted the floodplains into peatland where accumulation of peat almost to 2.0-3.0 m thickness in coastal lowlands and river basins during the shorter interval in the Middle Holocene. Vast areas of the coastal plains of Kerala have been converted into carbon rich peatland during the Middle Holocene and transforming the entire coastal stretch and associated landforms as one of the relatively youngest peatlands in the extreme southern tip of India. Unlike the uninterrupted formation of peatlands of considerable extent during the Holocene in Southeast Asia, the south Peninsular Indian region has restricted and short intervals of peatlands in the floodplains and coastal lowlands. Such a scenario is attributed to the topographic relief of the terrain and the prevailing hydrological regimes and environmental conditions as a consequence of monsoon variability since Middle Holocene in SW India. Considering the tropical coastal lowlands and associated peatlands are excellent repositories of carbon, they are very important for regional carbon cycling and habitat diversity. The

  19. Tropical Peat and Peatland Development in the Floodplains of the Greater Pamba Basin, South-Western India during the Holocene.

    Science.gov (United States)

    Kumaran, Navnith K P; Padmalal, Damodaran; Limaye, Ruta B; S, Vishnu Mohan; Jennerjahn, Tim; Gamre, Pradeep G

    2016-01-01

    Holocene sequences in the humid tropical region of Kerala, South-western (SW) India have preserved abundance of organic-rich sediments in the form of peat and its rapid development in a narrow time frame towards Middle Holocene has been found to be significant. The sub-coastal areas and flood plains of the Greater Pamba Basin have provided palaeorecords of peat indicating that the deposits are essentially formed within freshwater. The combination of factors like stabilized sea level and its subsequent fall since the Middle Holocene, topographic relief and climatic conditions led to rapid peat accumulation across the coastal lowlands. The high rainfall and massive floods coupled with a rising sea level must have inundated > 75% of the coastal plain land converting it into a veritable lagoon-lake system that eventually led to abrupt termination of the forest ecosystem and also converted the floodplains into peatland where accumulation of peat almost to 2.0-3.0 m thickness in coastal lowlands and river basins during the shorter interval in the Middle Holocene. Vast areas of the coastal plains of Kerala have been converted into carbon rich peatland during the Middle Holocene and transforming the entire coastal stretch and associated landforms as one of the relatively youngest peatlands in the extreme southern tip of India. Unlike the uninterrupted formation of peatlands of considerable extent during the Holocene in Southeast Asia, the south Peninsular Indian region has restricted and short intervals of peatlands in the floodplains and coastal lowlands. Such a scenario is attributed to the topographic relief of the terrain and the prevailing hydrological regimes and environmental conditions as a consequence of monsoon variability since Middle Holocene in SW India. Considering the tropical coastal lowlands and associated peatlands are excellent repositories of carbon, they are very important for regional carbon cycling and habitat diversity. The alarming rate of land

  20. Reef fish and benthic assemblages of the Trindade and Martin Vaz Island group, southwestern Atlantic

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    Guilherme Henrique Pereira-Filho

    2011-09-01

    Full Text Available The Trindade and Martin Vaz island group (TMVIG is located at about 1,120 km off the Brazilian coast. Despite its importance, highlighted by the presence of several endemic fish species, the TMVIG lacks detailed information on the structure of fish and benthic assemblages. Presented here is the first quantitative assessment of reef fish and benthic assemblages of the TMVIG in a depth gradient ranging from 5 to 45 m. Additional qualitative information on reef assemblages between 45 and 100 m was obtained using advanced gas diving techniques (TRIMIX and a remotely operated vehicle (ROV. Similarly to other Brazilian oceanic islands, the TMVIG possesses depauperated fish and benthic assemblages, possibly due to its isolation and small size in comparison to the mainland. Depth was the most important factor affecting the structure of fish assemblages, with the density of most fish species declining with depth. Deep reefs (> 45 m were characterized by the presence of extensive rhodolith beds and rocky reefs sparsely covered with crustose coralline algae, black coral (Cirripathes sp. and a few massive or plate-like reef corals. Part-time or obligatory planktivorous fishes (e.g. Cephalopholis furcifer and Clepticus brasiliensis also dominated deep reefs. Similar characteristics were recorded in mesophotic reef ecosystems across the Western Atlantic. Evidence of overfishing (obtained here and in other recent studies, the presence of four endemic and restricted range fish species, as well as the increase in number of new (and still undescribed endemic taxa, indicates that the adoption of precautionary conservation measures are urgently needed in order to maintain the fragile and unique ecosystems of the TMVIG.O conjunto insular de Trindade e Martin Vaz (CITMV está localizado a aproximadamente 1.120 km da costa brasileira. Apesar de sua importância, salientada pela presença de diversas espécies endêmicas de peixes, não existem informações detalhadas

  1. Quantifying changes of wind speed distributions in the historical record of Atlantic tropical cyclones

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    K. Chen

    2009-10-01

    Full Text Available Here we re-examine the official Atlantic basin tropical cyclone (hurricane database HURDAT (1851–2008 and quantify differences between wind speed distributions in the early historical (1851–1943 record and more recent observations. Analyses were performed at three different geographical levels: for all six-hourly track segments of all Atlantic basin events, all segments of all events that crossed the US mainland, and US landfalling segments alone. At all three geographical levels of study, distributions of windspeeds over the last two, four and six decades display negligible dispersion or systematic change over time. On the other hand and relative to wind speed frequencies for subsequent years, the 1851–1943 record has a marked and statistically significant over-representation of wind speeds largely corresponding to Saffir-Simpson Categories 1 and 2 and under-representation of Categories 4 and 5 events; importantly, no single Category 5 event is recorded prior to 1924. The stability of the distribution of windspeeds at landfall over the last six decades, the dataset in which we can have most confidence, suggests that the differences in the earlier record are most likely explained by well-known measurement and observational deficiencies. Moreover by disaggregating the Power Dissipation Index (PDI, we demonstrate that the upward trend in Atlantic basin PDI since 1970s does not imply stronger and longer duration Category 5 windspeeds despite a warming climate. These results have implications for hurricane catastrophe loss modeling for the insurance industry and long-term trend analyses of the historical wind speed record, especially those related to the attribution of the role of Global Climate Change.

  2. Rapid biological oxidation of methanol in the tropical Atlantic: significance as a microbial carbon source

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    J. L. Dixon

    2011-09-01

    Full Text Available Methanol is the second most abundant organic gas in the atmosphere after methane, and is ubiquitous in the troposphere. It plays a significant role in atmospheric oxidant chemistry and is biogeochemically active. Large uncertainties exist about whether the oceans are a source or sink of methanol to the atmosphere. Even less is understood about what reactions in seawater determine its concentration, and hence flux across the sea surface interface. We report here concentrations of methanol between 151–296 nM in parts of the oligotrophic North Atlantic, with corresponding microbial uptake rates between 2–146 nM d−1, suggesting turnover times as low as 1 day (1–25 days in surface waters of the oligotrophic tropical North East Atlantic. Methanol is mainly (≥97% used by microbes for obtaining energy in oligotrophic regions, which contrasts with shelf and coastal areas where between 20–50% can be used for cell growth. Comparisons of microbial methanol oxidation rates with parallel determinations of bacterial leucine uptake suggest that methanol contributes on average 13% to bacterial carbon demand in the central northern Atlantic gyre (maximum of 54%. In addition, the contribution that methanol makes to bacterial carbon demand varies as a power function of chlorophyll a concentrations; suggesting for concentrations <0.2 μg l−1 that methanol can make a significant contribution to bacterial carbon demand. However, our low air to sea methanol flux estimates of 7.2–13 μmol m−2 d−1 suggest that the atmosphere is not a major methanol source. We conclude that there must be a major, as yet unidentified, in situ oceanic methanol source in these latitudes which we suggest is sunlight driven decomposition of organic matter.

  3. Rapid biological oxidation of methanol in the tropical Atlantic: significance as a microbial carbon source

    Science.gov (United States)

    Dixon, J. L.; Beale, R.; Nightingale, P. D.

    2011-09-01

    Methanol is the second most abundant organic gas in the atmosphere after methane, and is ubiquitous in the troposphere. It plays a significant role in atmospheric oxidant chemistry and is biogeochemically active. Large uncertainties exist about whether the oceans are a source or sink of methanol to the atmosphere. Even less is understood about what reactions in seawater determine its concentration, and hence flux across the sea surface interface. We report here concentrations of methanol between 151-296 nM in parts of the oligotrophic North Atlantic, with corresponding microbial uptake rates between 2-146 nM d-1, suggesting turnover times as low as 1 day (1-25 days) in surface waters of the oligotrophic tropical North East Atlantic. Methanol is mainly (≥97%) used by microbes for obtaining energy in oligotrophic regions, which contrasts with shelf and coastal areas where between 20-50% can be used for cell growth. Comparisons of microbial methanol oxidation rates with parallel determinations of bacterial leucine uptake suggest that methanol contributes on average 13% to bacterial carbon demand in the central northern Atlantic gyre (maximum of 54%). In addition, the contribution that methanol makes to bacterial carbon demand varies as a power function of chlorophyll a concentrations; suggesting for concentrations methanol can make a significant contribution to bacterial carbon demand. However, our low air to sea methanol flux estimates of 7.2-13 μmol m-2 d-1 suggest that the atmosphere is not a major methanol source. We conclude that there must be a major, as yet unidentified, in situ oceanic methanol source in these latitudes which we suggest is sunlight driven decomposition of organic matter.

  4. Ecosystem carbon storage and partitioning in a tropical seasonal forest in Southwestern China

    DEFF Research Database (Denmark)

    Lü, Xiao-Tao; Yin, Jiang-Xia; Jepsen, Martin Rudbeck

    2010-01-01

    in Malaysia. The variation of C storage in the tree layer among different plots was mainly due to different densities of large trees (DBH > 70 cm). The contributions of the shrub layer, herb layer, woody lianas, and fine litter each accounted for 1-2 t C ha-1 to the total carbon stock. The mineral soil C...... pools (top 100 cm) ranged from 84 to 102 t C ha-1 and the C in woody debris from 5.6 to 12.5 t C ha-1, representing the second and third largest C component in this ecosystem. Our results reveal that a high percentage (70%) of C is stored in biomass and less in soil in this tropical seasonal forest...

  5. Synoptic-Scale Precursors to Tropical Cyclone Rapid Intensification in the Atlantic Basin

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    Alexandria Grimes

    2015-01-01

    Full Text Available Forecasting rapid intensification (hereafter referred to as RI of tropical cyclones in the Atlantic Basin is still a challenge due to a limited understanding of the meteorological processes that are necessary for predicting RI. To address this challenge, this study considered large-scale processes as RI indicators within tropical cyclone environments. The large-scale processes were identified by formulating composite map types of RI and non-RI storms using NASA MERRA data from 1979 to 2009. The composite fields were formulated by a blended RPCA and cluster analysis approach, yielding multiple map types of RI’s and non-RI’s. Additionally, statistical differences in the large-scale processes were identified by formulating permutation tests, based on the composite output, revealing variables that were statistically significantly distinct between RI and non-RI storms. These variables were used as input in two prediction schemes: logistic regression and support vector machine classification. Ultimately, the approach identified midlevel vorticity, pressure vertical velocity, 200–850 hPa vertical shear, low-level potential temperature, and specific humidity as the most significant in diagnosing RI, yielding modest skill in identifying RI storms.

  6. An Estimate of the North Atlantic Basin Tropical Cyclone Activity for the 2010 Hurricane Season

    Science.gov (United States)

    Wilson, Robert M.

    2010-01-01

    Estimates are presented for the tropical cyclone activity expected for the 2010 North Atlantic basin hurricane season. It is anticipated that the 2010 season will be more active than the 2009 season, reflecting increased frequencies more akin to that of the current more active phase that has been in vogue since 1995. Averages (+/- 1 sd) during the current more active phase are 14.5+/-4.7, 7.8+/-3.2, 3.7+/-1.8, and 2+/- 2, respectively, for the number of tropical cyclones (NTC), the number of hurricanes (NH), the number of major hurricanes (NMH), and the number of United States (U.S.) land-falling hurricanes (NUSLFH). Based on the "usual" behavior of the 10-yma parametric first differences, one expects NTC = 19+/-2, NH = 14+/-2, NMH = 7+/-2, and NUSLFH = 4+/-2 for the 2010 hurricane season; however, based on the "best guess" 10-yma values of surface-air temperature at the Armagh Observatory (Northern Ireland) and the Oceanic Nino Index, one expects NTC > or equals 16, NH > or equals 14, NMH > or equals 7, and NUSLFH > or equals 6.

  7. Tropical Atlantic Hurricanes, Easterly Waves, and West African Mesoscale Convective Systems

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    Yves K. Kouadio

    2010-01-01

    Full Text Available The relationship between tropical Atlantic hurricanes (Hs, atmospheric easterly waves (AEWs, and West African mesoscale convective systems (MCSs is investigated. It points out atmospheric conditions over West Africa before hurricane formation. The analysis was performed for two periods, June–November in 2004 and 2005, during which 12 hurricanes (seven in 2004, five in 2005 were selected. Using the AEW signature in the 700 hPa vorticity, a backward trajectory was performed to the African coast, starting from the date and position of each hurricane, when and where it was catalogued as a tropical depression. At this step, using the Meteosat-7 satellite dataset, we selected all the MCSs around this time and region, and tracked them from their initiation until their dissipation. This procedure allowed us to relate each of the selected Hs with AEWs and a succession of MCSs that occurred a few times over West Africa before initiation of the hurricane. Finally, a dipole in sea surface temperature (SST was observed with a positive SST anomaly within the region of H generation and a negative SST anomaly within the Gulf of Guinea. This SST anomaly dipole could contribute to enhance the continental convergence associated with the monsoon that impacts on the West African MCSs formation.

  8. Decadal interactions between the western tropical Pacific and the North Atlantic Oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Kucharski, Fred; Molteni, Franco; Bracco, Annalisa [Abdus Salam International Centre for Theoretical Physics, Physics of Weather and Climate Section, Trieste (Italy)

    2006-01-01

    The relationship between interdecadal variations of tropical sea surface temperature (SST) in the last 120 years and circulation anomalies related to the North Atlantic Oscillation (NAO) is investigated in this study. Using an atmospheric general circulation model (AGCM), we confirm observational evidence that variations in the SST gradient in the western tropical Pacific are related to the NAO anomalies on decadal timescale, and may be contributing to the shift towards the positive NAO phase observed in the late 20th century. The role played by the Indian Ocean-NAO teleconnection, advocated in recent studies focused on the last 50 years, is also assessed in the context of the 120-year long record. It is suggested that a positive feedback between the Pacific SST and the hemispheric circulation pattern embedding the decadal NAO signal may act to enhance the internal variability of the coupled ocean-atmosphere system, and justify the stronger teleconnection found in observational data than in SST-forced AGCM experiments. (orig.)

  9. Characterization and impact of "dead-zone" eddies in the tropical Northeast Atlantic Ocean

    Science.gov (United States)

    Schuette, Florian; Karstensen, Johannes; Krahmann, Gerd; Hauss, Helena; Fiedler, Björn; Brandt, Peter; Visbeck, Martin; Körtzinger, Arne

    2016-04-01

    Localized open-ocean low-oxygen dead-zones in the tropical Northeast Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic modewater eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats shows that eddies with low oxygen concentrations at 50-150 m depths can be found in surprisingly high numbers and in a large area (from about 5°N to 20°N, from the shelf at the eastern boundary to 30°W). Minimum oxygen concentrations of about 9 μmol/kg in CEs and close to anoxic concentrations (dead-zone" eddies (10 CEs; 17 ACMEs). The low oxygen concentration right beneath the mixed layer has been attributed to the combination of high productivity in the surface waters of the eddies and the isolation of the eddies' cores. Indeed eddies of both types feature a cold sea surface temperature anomaly and enhanced chlorophyll concentrations in their center. The oxygen minimum is located in the eddy core beneath the mixed layer at around 80 m depth. The mean oxygen anomaly between 50 to 150 m depth for CEs (ACMEs) is -49 (-81) μmol/kg. Eddies south of 12°N carry weak hydrographic anomalies in their cores and seem to be generated in the open ocean away from the boundary. North of 12°N, eddies of both types carry anomalously low salinity water of South Atlantic Central Water origin from the eastern boundary upwelling region into the open ocean. This points to an eddy generation near the eastern boundary. A conservative estimate yields that around 5 dead-zone eddies (4 CEs; 1 ACME) per year entering the area north of 12°N between the Cap Verde Islands and 19°W. The associated contribution to the oxygen budget of the shallow oxygen minimum zone in that area is about -10.3 (-3.0) μmol/kg/yr for CEs (ACMEs). The consumption within these eddies represents an essential part of the total consumption in the open tropical

  10. Reconstructing medieval climate in the tropical North Atlantic with corals from Anegada, British Virgin Islands

    Science.gov (United States)

    Kilbourne, K. H.; Xu, Y. Y.

    2014-12-01

    Resolving the patterns of climate variability during the Medieval Climate Anomaly (MCA) is key for exploring forced versus unforced variability during the last 1000 years. Tropical Atlantic climate is currently not well resolved during the MCA despite it being an important source of heat and moisture to the climate system today. To fill this data gap, we collected cores from Diploria strigosa corals brought onto the low-lying island of Anegada, British Virgin Islands (18.7˚N, 64.3˚S) during an overwash event and use paired analysis of Sr/Ca and δ18O in the skeletal aragonite to explore climate in the tropical Atlantic at the end of the MCA. The three sub-fossil corals used in this analysis overlap temporally and together span the years 1256-1372 C.E. An assessment of three modern corals from the study site indicates that the most robust features of climate reconstructions using Sr/Ca and δ18O in this species are the seasonal cycle and inter-annual variability. The modern seasonal temperature range is 2.8 degrees Celsius and the similarity between the modern and sub-fossil coral Sr/Ca indicates a similar range during the MCA. Today seasonal salinity changes locally are driven in large part by the migration of a regional salinity front. The modern corals capture the related large seasonal seawater δ18O change, but the sub-fossil corals indicate stable seawater δ18O throughout the year, supporting the idea that this site remained on one side of the salinity front continuously throughout the year. Inter-annual variability in the region is influenced by the cross-equatorial SST gradient, the North Atlantic Oscillation and ENSO. Gridded instrumental SST from the area surrounding Anegada and coral geochemical records from nearby Puerto Rico demonstrate concentrations of variance in specific frequency bands associated with these phenomena. The sub-fossil coral shows no concentration of variance in the modern ENSO frequency band, consistent with reduced ENSO

  11. Tropical SST forcing on the anomalous WNP subtropical high during July-August 2010 and the record-high SST in the tropical Atlantic

    Science.gov (United States)

    Hong, Chi-Cherng; Lee, Ming-Ying; Hsu, Huang-Hsiung; Lin, Nai-Hsin; Tsuang, Ben-Jei

    2015-08-01

    In summer of 2010, the western North Pacific subtropical high (WNPSH) was extremely strong and exhibited unusual westward extension, which resulted in record-breaking warmth in Japan and considerably below-normal and westward-shifted tropical cyclone activity in the western North Pacific (WNP). Although a moderate La Niña occurred, the sea surface temperature (SST) in the northern Indian Ocean (NIO) and tropical Atlantic (TA) was considerably high. In this study, we argued that the La Niña cold SST alone was not sufficient to maintain the strong WNPSH of 2010, and that the unusually warm SSTs in the NIO and TA markedly contributed to the enhancement and westward shift of the WNPSH in the boreal summer of that year. We focused on the effects of sea surface temperature anomalies in the tropical Atlantic (TA-SSTAs), which have been seldom explored and are poorly understood compared with the effects of SSTAs in the tropical Pacific and NIO. The warm TA-SST forced a westward-extending overturning circulation, with a sinking branch over the central Pacific Ocean, which produced a remote response similar to the La Niña condition and enhanced the WNPSH. The warm TA-SST also induced the cyclonic anomaly in the tropical eastern North Pacific, a distinct phenomenon not observed in a canonical La Niña event. Furthermore, we demonstrated that the anomalous near-surface circulation associated with the negative North Atlantic Oscillation might play a more dominant role than that of the 2009 El Niño in inducing the record-high SST in the TA in 2010.

  12. Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean.

    Science.gov (United States)

    Read, Katie A; Mahajan, Anoop S; Carpenter, Lucy J; Evans, Mathew J; Faria, Bruno V E; Heard, Dwayne E; Hopkins, James R; Lee, James D; Moller, Sarah J; Lewis, Alastair C; Mendes, Luis; McQuaid, James B; Oetjen, Hilke; Saiz-Lopez, Alfonso; Pilling, Michael J; Plane, John M C

    2008-06-26

    Increasing tropospheric ozone levels over the past 150 years have led to a significant climate perturbation; the prediction of future trends in tropospheric ozone will require a full understanding of both its precursor emissions and its destruction processes. A large proportion of tropospheric ozone loss occurs in the tropical marine boundary layer and is thought to be driven primarily by high ozone photolysis rates in the presence of high concentrations of water vapour. A further reduction in the tropospheric ozone burden through bromine and iodine emitted from open-ocean marine sources has been postulated by numerical models, but thus far has not been verified by observations. Here we report eight months of spectroscopic measurements at the Cape Verde Observatory indicative of the ubiquitous daytime presence of bromine monoxide and iodine monoxide in the tropical marine boundary layer. A year-round data set of co-located in situ surface trace gas measurements made in conjunction with low-level aircraft observations shows that the mean daily observed ozone loss is approximately 50 per cent greater than that simulated by a global chemistry model using a classical photochemistry scheme that excludes halogen chemistry. We perform box model calculations that indicate that the observed halogen concentrations induce the extra ozone loss required for the models to match observations. Our results show that halogen chemistry has a significant and extensive influence on photochemical ozone loss in the tropical Atlantic Ocean boundary layer. The omission of halogen sources and their chemistry in atmospheric models may lead to significant errors in calculations of global ozone budgets, tropospheric oxidizing capacity and methane oxidation rates, both historically and in the future.

  13. Recent Atlantic Hurricanes, Pacific Super Typhoons, and Tropical Storm Awareness in Underdeveloped Island and Coastal Regions

    Science.gov (United States)

    Plondke, D. L.

    2017-12-01

    Hurricane Harvey was the first major hurricane to make landfall in the continental U.S. in 12 years. The next tropical storm in the 2017 Atlantic Hurricane Season was Hurricane Irma, a category 5 storm and the strongest storm to strike the U.S. mainland since Hurricane Wilma in 2005. These two storms were the third and fourth in a sequence of 10 consecutive storms to reach hurricane status in this season that ranks at least seventh among the most active seasons as measured by the Accumulate Cyclone Energy (ACE) index. Assessment of damage from Harvey may prove it to be the costliest storm in U.S. history, approaching $190 billion. Irma was the first category 5 hurricane to hit the Leeward Islands, devastating island environments including Puerto Rico, the Virgin Islands, Barbuda, Saint Barthelemy, and Anguilla with sustained winds reaching at times 185 mph. Together with the two super typhoons of the 2017 Pacific season, Noru and Lan, the two Atlantic hurricanes rank among the strongest, longest-lasting tropical cyclones on record. How many more billions of dollars will be expended in recovery and reconstruction efforts following future mega-disasters comparable to those of Hurricanes Harvey and Irma? Particularly on Caribbean and tropical Pacific islands with specialized and underdeveloped economies, aging and substandard infrastructure often cannot even partially mitigate against the impacts of major hurricanes. The most frequently used measurements of storm impact are insufficient to assess the economic impact. Analysis of the storm tracks and periods of greatest storm intensity of Hurricanes Harvey and Irma, and Super Typhoons Lan and Noru, in spatial relationship with island and coastal administrative regions, shows that rainfall totals, flooded area estimates, and property/infrastructure damage dollar estimates are all quantitative indicators of storm impact, but do not measure the costs that result from lack of storm preparedness and education of residents

  14. Tropical Atlantic climate and ecosystem regime shifts during the Paleocene-Eocene Thermal Maximum

    Science.gov (United States)

    Frieling, Joost; Reichart, Gert-Jan; Middelburg, Jack J.; Röhl, Ursula; Westerhold, Thomas; Bohaty, Steven M.; Sluijs, Appy

    2018-01-01

    The Paleocene-Eocene Thermal Maximum (PETM, 56 Ma) was a phase of rapid global warming associated with massive carbon input into the ocean-atmosphere system from a 13C-depleted reservoir. Many midlatitude and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning, and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP) Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst) assemblage analysis. The PETM at Site 959 was previously found to be marked by a ˜ 3.8 ‰ negative carbon isotope excursion (CIE) and a ˜ 4 °C surface ocean warming from the uppermost Paleocene to peak PETM, of which ˜ 1 °C occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extratropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close-by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth in the eastern equatorial Atlantic, most likely caused by heat stress. We hypothesize, based on a literature survey, that heat stress might have reduced calcification in more tropical regions, potentially contributing to reduced deep sea carbonate accumulation rates, and, by buffering acidification, also to biological carbonate compensation of the injected carbon during the PETM. Crucially, abundant organic benthic foraminiferal linings imply sustained export production, likely driven by prokaryotes. In

  15. Tropical Atlantic climate and ecosystem regime shifts during the Paleocene–Eocene Thermal Maximum

    Directory of Open Access Journals (Sweden)

    J. Frieling

    2018-01-01

    Full Text Available The Paleocene–Eocene Thermal Maximum (PETM, 56 Ma was a phase of rapid global warming associated with massive carbon input into the ocean–atmosphere system from a 13C-depleted reservoir. Many midlatitude and high-latitude sections have been studied and document changes in salinity, hydrology and sedimentation, deoxygenation, biotic overturning, and migrations, but detailed records from tropical regions are lacking. Here, we study the PETM at Ocean Drilling Program (ODP Site 959 in the equatorial Atlantic using a range of organic and inorganic proxies and couple these with dinoflagellate cyst (dinocyst assemblage analysis. The PETM at Site 959 was previously found to be marked by a  ∼  3.8 ‰ negative carbon isotope excursion (CIE and a  ∼  4 °C surface ocean warming from the uppermost Paleocene to peak PETM, of which  ∼  1 °C occurs before the onset of the CIE. We record upper Paleocene dinocyst assemblages that are similar to PETM assemblages as found in extratropical regions, confirming poleward migrations of ecosystems during the PETM. The early stages of the PETM are marked by a typical acme of the tropical genus Apectodinium, which reaches abundances of up to 95 %. Subsequently, dinocyst abundances diminish greatly, as do carbonate and pyritized silicate microfossils. The combined paleoenvironmental information from Site 959 and a close-by shelf site in Nigeria implies the general absence of eukaryotic surface-dwelling microplankton during peak PETM warmth in the eastern equatorial Atlantic, most likely caused by heat stress. We hypothesize, based on a literature survey, that heat stress might have reduced calcification in more tropical regions, potentially contributing to reduced deep sea carbonate accumulation rates, and, by buffering acidification, also to biological carbonate compensation of the injected carbon during the PETM. Crucially, abundant organic benthic foraminiferal linings imply

  16. Nonlinear interactions between the Amazon River basin and the Tropical North Atlantic at interannual timescales

    Science.gov (United States)

    Builes-Jaramillo, Alejandro; Marwan, Norbert; Poveda, Germán; Kurths, Jürgen

    2017-07-01

    We study the physical processes involved in the potential influence of Amazon (AM) hydroclimatology over the Tropical North Atlantic (TNA) Sea Surface Temperatures (SST) at interannual timescales, by analyzing time series of the precipitation index (P-E) over AM, as well as the surface atmospheric pressure gradient between both regions, and TNA SSTs. We use a recurrence joint probability based analysis that accounts for the lagged nonlinear dependency between time series, which also allows quantifying the statistical significance, based on a twin surrogates technique of the recurrence analysis. By means of such nonlinear dependence analysis we find that at interannual timescales AM hydrology influences future states of the TNA SSTs from 0 to 2 months later with a 90-95% statistical confidence. It also unveils the existence of two-way feedback mechanisms between the variables involved in the processes: (1) precipitation over AM leads the atmospheric pressure gradient between TNA and AM from 0 to 2 month lags, (2) the pressure gradient leads the trade zonal winds over the TNA from 0 to 3 months and from 7 to 12 months, (3) the zonal winds lead the SSTs from 0 to 3 months, and (4) the SSTs lead precipitation over AM by 1 month lag. The analyses were made for time series spanning from 1979 to 2008, and for extreme precipitation events in the AM during the years 1999, 2005, 2009 and 2010. We also evaluated the monthly mean conditions of the relevant variables during the extreme AM droughts of 1963, 1980, 1983, 1997, 1998, 2005, and 2010, and also during the floods of 1989, 1999, and 2009. Our results confirm that the Amazon River basin acts as a land surface-atmosphere bridge that links the Tropical Pacific and TNA SSTs at interannual timescales. The identified mutual interactions between TNA and AM are of paramount importance for a deeper understanding of AM hydroclimatology but also of a suite of oceanic and atmospheric phenomena over the TNA, including recently

  17. Nonlinear interactions between the Amazon River basin and the Tropical North Atlantic at interannual timescales

    Science.gov (United States)

    Builes-Jaramillo, Alejandro; Marwan, Norbert; Poveda, Germán; Kurths, Jürgen

    2018-04-01

    We study the physical processes involved in the potential influence of Amazon (AM) hydroclimatology over the Tropical North Atlantic (TNA) Sea Surface Temperatures (SST) at interannual timescales, by analyzing time series of the precipitation index (P-E) over AM, as well as the surface atmospheric pressure gradient between both regions, and TNA SSTs. We use a recurrence joint probability based analysis that accounts for the lagged nonlinear dependency between time series, which also allows quantifying the statistical significance, based on a twin surrogates technique of the recurrence analysis. By means of such nonlinear dependence analysis we find that at interannual timescales AM hydrology influences future states of the TNA SSTs from 0 to 2 months later with a 90-95% statistical confidence. It also unveils the existence of two-way feedback mechanisms between the variables involved in the processes: (1) precipitation over AM leads the atmospheric pressure gradient between TNA and AM from 0 to 2 month lags, (2) the pressure gradient leads the trade zonal winds over the TNA from 0 to 3 months and from 7 to 12 months, (3) the zonal winds lead the SSTs from 0 to 3 months, and (4) the SSTs lead precipitation over AM by 1 month lag. The analyses were made for time series spanning from 1979 to 2008, and for extreme precipitation events in the AM during the years 1999, 2005, 2009 and 2010. We also evaluated the monthly mean conditions of the relevant variables during the extreme AM droughts of 1963, 1980, 1983, 1997, 1998, 2005, and 2010, and also during the floods of 1989, 1999, and 2009. Our results confirm that the Amazon River basin acts as a land surface-atmosphere bridge that links the Tropical Pacific and TNA SSTs at interannual timescales. The identified mutual interactions between TNA and AM are of paramount importance for a deeper understanding of AM hydroclimatology but also of a suite of oceanic and atmospheric phenomena over the TNA, including recently

  18. Sensitivity of Tropical Cyclones to Resolution, Convection Scheme and Ocean Flux Parameterization over Eastern Tropical Pacific and Tropical North Atlantic Oceans in RegCM4 Model

    Science.gov (United States)

    Fuentes-Franco, Ramon; Giorgi, Filippo; Coppola, Erika; Zimmermann, Klaus

    2016-04-01

    The sensitivity of simulated tropical cyclones (TC) to resolution and convection scheme parameterization is investigated over the CORDEX Central America domain. The performance of the simulations, performed for a ten-year period (1989-1998) using ERA-Interim reanalysis as boundary and initial conditions, is assessed considering 50 km and 25 km resolution, and the use of two different convection schemes: Emanuel (Em) and Kain-Fritsch (KF). Two ocean surface fluxes are also compared as well: the Monin-Obukhov scheme, and the one proposed by Zeng et al. (1998). By comparing with observations, for the whole period we assess the spatial representation of the TC, and their intensity. At interannual scale we assess the representation of their variability and at daily scale we compare observed and simulated tracks in order to establish a measure of how similar to observed are the simulated tracks. In general the simulations using KF convection scheme show higher TC density, as well as longer-duration TC (up to 15 days) with stronger winds (> 50ms-1) than those using Em (<40ms-1). Similar results were found for simulations using 25 km respect to 50 km resolution. All simulations show a better spatial representation of simulated TC density and its interannual variability over the Tropical North Atlantic Ocean (TNA) than over the Eastern Tropical Pacific Ocean (ETP). The 25 km resolution simulations show an overestimation of TC density compared to observations over ETP off the coast of Mexico. The duration of the TC in simulations using 25km resolution is similar to the observations, while is underestimated by the 50km resolution. The Monin-Obukhov ocean flux overestimates the number of TCs, while Zeng parameterization give a number similar to observations in both oceans. At daily scale, in general all simulations capture the density of cyclones during highly active TC seasons over the TNA, however the tracks generally are not coincident with observations, except for highly

  19. Dominant Role of Atlantic Multidecadal Oscillation in the Recent Decadal Changes in Western North Pacific Tropical Cyclone Activity

    Science.gov (United States)

    Zhang, Wei; Vecchi, Gabriel A.; Murakami, Hiroyuki; Villarini, Gabriele; Delworth, Thomas L.; Yang, Xiaosong; Jia, Liwei

    2018-01-01

    Over the 1997-2014 period, the mean frequency of western North Pacific (WNP) tropical cyclones (TCs) was markedly lower ( 18%) than the period 1980-1996. Here we show that these changes were driven by an intensification of the vertical wind shear in the southeastern/eastern WNP tied to the changes in the Walker circulation, which arose primarily in response to the enhanced sea surface temperature (SST) warming in the North Atlantic, while the SST anomalies associated with the negative phase of the Pacific Decadal Oscillation in the tropical Pacific and the anthropogenic forcing play only secondary roles. These results are based on observations and experiments using the Geophysical Fluid Dynamics Laboratory Forecast-oriented Low-ocean Resolution Coupled Climate Model coupled climate model. The present study suggests a crucial role of the North Atlantic SST in causing decadal changes to WNP TC frequency.

  20. Vegetation and pollen rain relationship from the tropical Atlantic rain forest in Southern Brazil

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    Hermann Behling

    2006-07-01

    Full Text Available The relationship between the southern Brazilian tropical Atlantic lowland rain forest and modern pollen rain was studied by pollen traps. The study was carried out on a one hectare plot undisturbed rain forest of the reserve Volta Velha and two secondary forests, ± 50 and 7 years old. About 248 identified tree, shrub and herb species (excluding epiphytes of 50 families were represented by 126 different pollen and spore types (including non-local taxa. The calculated average influx of pollen rain from the native Atlantic rain forest was 12465 pollen grains per cm² and year. The influx from the ± 50 years old and from the 7 years old secondary forest was relatively low (4112 and 3667 grains per cm² and year, respectively compared to the undisturbed rain forest. The occurrence of pollen grains of herbs and fern spores were significantly higher in the secondary forests than in the undisturbed rain forest.Estudou-se a relação entre a Floresta Tropical Atlântica sul brasileira e a chuva polínica atual através de coletores de pólen. O estudo foi realizado em uma parcela de um hectare de floresta não perturbada localizada na Reserva Volta Velha (26º 04' S, 48º 38' W, 9 m s.n.m. e duas outras parcelas de floresta secundária (± 50 e 7 anos de idade. Cerca de 248 espécies arbóreas, arbustivas e herbáceas (excluindo epifitas, englobadas em 50 familias estavam representadas por 126 diferentes tipos de pólen e esporos (incluindo taxa não locais. Na área não perturbada, a média do fluxo de entrada da chuva polínica foi de 12465 grãos de pólen por cm²/ano. Nas áreas de ± 50 anos e 7 anos correspondentes a estádios florestais secundários o fluxo de entrada foi relativamente baixo (4112 e 3667 grãos por cm²/ano, respectivamente comparativamente à área não perturbada. A ocorrência de grãos de pólen de herbáceas e esporos de pteridófitas foi significativamente maior nas áreas secundárias do que na área não perturbada.

  1. Satellite chlorophyll-a annual bloom characterization in Northeast Brazil, western tropical Atlantic

    Science.gov (United States)

    Kampel, Milton; Rudorff, Natalia M.; Dall Cortivo, Fabio; Freitas, Lucas B.; Valerio, Larissa P.

    2014-11-01

    Time series of satellite-derived sea surface chlorophyll concentration (SSC) from 2002 to 2012 were used to investigate the phenology of phytoplankton bloom in the Sergipe-Alagoas Basin, located in Northeast Brazil, Western Tropical Atlantic. The seasonal phytoplankton cycle is the dominant mode of temporal variability. The use of a Gaussian function to fit the temporal variability of SSC allowed the characterization of the timing and magnitude of the annual phytoplankton bloom in the slope and continental shelf areas. Modeled SSC showed a few differences in relation to mean MODIS-derived temporal curves. The maximum error was 0.14 mg.m-3 in September on the shelf and 0.006 mg.m- 3 in February on the slope. In both areas, SSC data showed that the maximum surface bloom occurs in June, having initiated in March. This cycle is typical of tropical waters of low latitudes where bloom is initiated at lower vertical stability of the water column allowing nutrients from deeper layers to fertilize usually poor and warm waters of the mixed layer. High rainfall increases the continental drainage into the shelf in autumn-winter, which may affect the timing of bloom. However, the flow regulation of the most important river in the region (Sao Francisco River) decreases the potential impact of river inflow in the coastal region. As the shelf and slope showed very similar patterns, it is likely that the processes of wind mixing and water heating/cooling are the most determining factors for the annual cycle of phytoplankton bloom in this region.

  2. Water-soluble elements in atmospheric particulate matter over tropical and equatorial Atlantic

    Energy Technology Data Exchange (ETDEWEB)

    Buat-Menard, P.; Morelli, J.; Chesselet, R. (Centre National de la Recherche Scientifique, 91 - Gif-sur-Yvette (France). Centre des Faibles Radioactivites)

    1974-07-01

    Samples of water-soluble atmospheric particulate matter collected from R/V ''Jean Charcot'' (May to October 1971) and R/V ''James Gilliss'' (October 1972) over Tropical and Equatorial Atlantic were analyzed for Na, Mg, K, and Ca by atomic absorption and for Cl and S as SO/sub 4/ by colorimetry. Data shows a strong geographical dependence of K and Ca enrichment relative to their elemental ratio to Na in seawater. Ca enrichment is related to presence of identified soluble calcium minerals in continental dust originating from African deserts (Sahara-Kalahari). This dust does not influence amounts of K in the water-soluble phase. When observed, strong K enrichment appears tightly associated with high concentrations of surface-active organic material in the microlayer derived from high biological activity (Gulf of Guinea). Observed in the same samples, SO/sub 4/ enrichment could also be controlled by the same source. This SO/sub 4/ enrichment balances the observed Cl loss in aerosols accordingly with gaseous HCl formation processes in marine atmosphere. (FR)

  3. Water-soluble elements in atmospheric particulate matter over tropical and equatorial Atlantic

    International Nuclear Information System (INIS)

    Buat-Menard, Patrick; Morelli, Jacques; Chesselet, Roger

    1974-01-01

    Samples of water-soluble atmospheric particulate matter collected from R/V ''Jean Charcot'' (May to October 1971) and R/V ''James Gilliss'' (October 1972) over Tropical and Equatorial Atlantic were analyzed for Na, Mg, K and Ca by atomic absorption and for Cl and S as SO 4 by colorimetry. Data shows a strong geographical dependence of K and Ca enrichment relative to their elemental ratio to Na in sea-water. Ca enrichment is related to presence of identified soluble calcium minerals in continental dust originating from African deserts (Sahara-Kalahari). This dust does not influence amounts of K in the water-soluble phase. When observed, strong K enrichment appears tightly associated with high concentrations of surface-active organic material in the microlayer derived from high biological activity (Gulf of Guinea). Observed in same samples, SO 4 enrichment could also be controlled by the same source. This SO 4 enrichment balances the observed Cl loss in aerosols accordingly with gaseous HCl formation processes in marine atmosphere [fr

  4. Seismic imaging of a thermohaline staircase in the western tropical North Atlantic

    Directory of Open Access Journals (Sweden)

    I. Fer

    2010-07-01

    Full Text Available Multichannel seismic data acquired in the Lesser Antilles in the western tropical North Atlantic indicate that the seismic reflection method has imaged an oceanic thermohaline staircase. Synthetic acoustic modeling using measured density and sound speed profiles corroborates inferences from the seismic data. In a small portion of the seismic image, laterally coherent, uniform layers are present at depths ranging from 550–700 m and have a separation of ~20 m, with thicknesses increasing with depth. The reflection coefficient, a measure of the acoustic impedance contrasts across these reflective interfaces, is one order of magnitude greater than background noise. Hydrography sampled in previous surveys suggests that the layers are a permanent feature of the region. Spectral analysis of layer horizons in the thermohaline staircase indicates that internal wave activity is anomalously low, suggesting weak internal wave-induced turbulence. Results from two independent measurements, the application of a finescale parameterization to observed high-resolution velocity profiles and direct measurements of turbulent dissipation rate, confirm these low levels of turbulence. The lack of internal wave-induced turbulence may allow for the maintenance of the staircase or may be due to suppression by the double-diffusive convection within the staircase. Our observations show the potential for seismic oceanography to contribute to an improved understanding of occurrence rates and the geographical distribution of thermohaline staircases, and should thereby improve estimates of vertical mixing rates ascribable to salt fingering in the global ocean.

  5. Simple climatic indices for the tropical Atlantic Ocean and some applications

    Science.gov (United States)

    Servain, Jacques

    1991-08-01

    Two indices related to the sea surface temperature (SST) variability in the tropical Atlantic are proposed. One index describes the SST averaged over the whole basin (30°N to 20°S, 60°W to 15°E), and the other illustrates a meridional dipole between the northern and southern hemispheres. The computational method for obtaining these indices is intentionally kept simple, the objective being to reproduce the signature of the main results previously provided from more complicated statistical analyses. Monthly time series for both indices are produced from 1964 up to the present time. The whole basin index exhibits principally a sustained warming which has intensified since about 1975, and it has a significant periodicity close to that of the quasi-biennial oscillation. The dipole index exhibits a decadal-scale variation, and its building up seems to be related to other worldwide climatic changes, as for instance El Niño / Southern Oscillation extreme episodes, rainfall variabilities over the Brazilian Nordeste and African Sahel.

  6. Atmospheric and oceanic dust fluxes in the northeastern tropical Atlantic Ocean: how close a coupling?

    Directory of Open Access Journals (Sweden)

    A. Bory

    2002-12-01

    Full Text Available Atmospheric inputs to the ocean of dust originating from Africa are compared with downward dust flux in the oceanic water column. Atmospheric fluxes were estimated using remote-sensing-derived dust optical thickness and parameters from a transport/deposition model (TM2z. Oceanic fluxes were measured directly over/in two regions of contrasting primary productivity of the northeastern tropical Atlantic (one mesotrophic and one oligotrophic, located at about 500 and 1500 km off Mauritania underlying the offshore dust plume. In both regions, estimates of annual atmospheric dust inputs to the ocean surface are lower than, but of the same order of magnitude as, oceanic fluxes (49.5 and 8.8 mg.m-2 .d-1 in the mesotrophic and oligotrophic regions. Part of this mismatch may reflect both a general flaw in the dust grain size distribution used in transport models, which likely underestimates large particles, and/or lateral advection to each region of dustier surface waters from upstream, where dust deposition is higher. Higher-frequency temporal coupling between atmospheric and oceanic fluxes seems to be primary-productivity dependent, as hypothesized in previously reported studies.Key words. Atmospheric composition and structure (aerosols and particles; geochemical cycles Oceanography: biological and chemical (geochemistry

  7. Serpula and Spiraserpula (Polychaeta, Serpulidae) from the Tropical Western Atlantic and Gulf of Guinea

    Science.gov (United States)

    Bastida-Zavala, Rolando

    2012-01-01

    Abstract Six species of Serpula and Spiraserpula were identified, mainly, from the material of the expeditions of the Rosenstiel School of Marine and Atmospheric Science, University of Miami, including two new species of Serpula. Serpula madrigalae sp. n. from the Turks and Caicos has a tube with five longitudinal ridges, four rows of alveoli and a medium-sized shallow symmetrical opercular funnel with 17 radii, and an inner surface with opercular tubercles. Serpula vossae sp. n. from the Western Caribbean and Bahamas has a tube with 6–8 longitudinal ridges, and a large, deep symmetrical opercular funnel, with 21–33 radii, and a smooth inner surface. Serpula cf. vermicularis, recorded from the Gulf of Guinea (tropical eastern Atlantic), is distinguished from the nominal species in possessing fewer opercular radii (33–39) and the lack of a proximal rasp in the bayonet chaetae; tubes are missing. The distribution range is extended for the three known Spiraserpula species found in the collections, Spiraserpula caribensis, Spiraserpula karpatensis and Spiraserpula ypsilon. PMID:22707904

  8. Effect of CO2 enrichment on phytoplankton photosynthesis in the North Atlantic sub-tropical gyre

    Science.gov (United States)

    Tilstone, Gavin; Šedivá, Barbora; Tarran, Glen; Kaňa, Radek; Prášil, Ondřej

    2017-11-01

    The effects of changes in CO2 concentration in seawater on phytoplankton community structure and photosynthesis were studied in the North Atlantic sub-tropical gyre. Three shipboard incubations were conducted for 48 h at ∼760 ppm CO2 and control (360 ppm CO2) from 49°N to 7°N during October and November 2010. Elevated CO2 caused a decrease in pH to ∼7.94 compared to ∼8.27 in the control. During one experiment, the biomass of nano- and picoeukaryotes increased under CO2 enrichment, but primary production decreased relative to the control. In two of the experiments the biomass was dominated by dinoflagellates, and there was a significant increase in the maximum photosynthetic rate (PmB) and light-limited slope of photosynthesis (αB) at CO2 concentrations of 760 ppm relative to the controls. 77 K emission spectroscopy showed that the higher photosynthetic rates measured under CO2 enrichment increased the connection of reversible photosystem antennae, which resulted in an increase in light harvesting efficiency and carbon fixation.

  9. Atmospheric and oceanic dust fluxes in the northeastern tropical Atlantic Ocean: how close a coupling?

    Directory of Open Access Journals (Sweden)

    A. Bory

    Full Text Available Atmospheric inputs to the ocean of dust originating from Africa are compared with downward dust flux in the oceanic water column. Atmospheric fluxes were estimated using remote-sensing-derived dust optical thickness and parameters from a transport/deposition model (TM2z. Oceanic fluxes were measured directly over/in two regions of contrasting primary productivity of the northeastern tropical Atlantic (one mesotrophic and one oligotrophic, located at about 500 and 1500 km off Mauritania underlying the offshore dust plume. In both regions, estimates of annual atmospheric dust inputs to the ocean surface are lower than, but of the same order of magnitude as, oceanic fluxes (49.5 and 8.8 mg.m-2 .d-1 in the mesotrophic and oligotrophic regions. Part of this mismatch may reflect both a general flaw in the dust grain size distribution used in transport models, which likely underestimates large particles, and/or lateral advection to each region of dustier surface waters from upstream, where dust deposition is higher. Higher-frequency temporal coupling between atmospheric and oceanic fluxes seems to be primary-productivity dependent, as hypothesized in previously reported studies.

    Key words. Atmospheric composition and structure (aerosols and particles; geochemical cycles Oceanography: biological and chemical (geochemistry

  10. Atmospheric and oceanic dust fluxes in the northeastern tropical Atlantic ocean: how close a coupling?

    Energy Technology Data Exchange (ETDEWEB)

    Bory, A. [Lab. des Sciences du Climat et de l' Environnement, Gif-sur-Yvette (France); Lamont-Doherty Earth Observatory, Columbia Univ., Palisades, NY (United States); Dulac, F.; Moulin, C.; Guelle, W.; Lambert, C.E. [Lab. des Sciences du Climat et de l' Environnement, Gif-sur-Yvette (France); Chiapello, I. [Lab. Inter-Univ. des Systemes Atmospheriques, Faculte des Sciences et Technologies, Creteil (France); Lab. d' Optique Atmospherique, Univ. des Sciences et Technologies de Lille, Villeneuve d' Ascq (France); Newton, P.P. [Lab. des Sciences du Climat et de l' Environnement, Gif-sur-Yvette (France); School of Biological and Molecular Sciences, Oxford Brookes Univ., Headington, Oxford (United Kingdom); Bergametti, G. [Lab. Inter-Univ. des Systemes Atmospheriques, Faculte des Sciences et Technologies, Creteil (France)

    2002-12-01

    Atmospheric inputs to the ocean of dust originating from Africa are compared with downward dust flux in the oceanic water column. Atmospheric fluxes were estimated using remote-sensing-derived dust optical thickness and parameters from a transport/deposition model (TM2z). Oceanic fluxes were measured directly over/in two regions of contrasting primary productivity of the northeastern tropical Atlantic (one mesotrophic and one oligotrophic, located at about 500 and 1500 km off Mauritania) underlying the off-shore dust plume. In both regions, estimates of annual atmospheric dust inputs to the ocean surface are lower than, but of the same order of magnitude as, oceanic fluxes (49.5 and 8.8 mg.m{sup -2}.d{sup -1} in the mesotrophic and oligotrophic regions). Part of this mismatch may reflect both a general flaw in the dust grain size distribution used in transport models, which likely underestimates large particles, and/or lateral advection to each region of dustier surface waters from upstream, where dust deposition is higher. Higher-frequency temporal coupling between atmospheric and oceanic fluxes seems to be primary-productivity dependent, as hypothesized in previously reported studies. (orig.)

  11. Decadal variability of the Tropical Atlantic Ocean Surface Temperature in shipboard measurements and in a Global Ocean-Atmosphere model

    Science.gov (United States)

    Mehta, Vikram M.; Delworth, Thomas

    1995-01-01

    Sea surface temperature (SST) variability was investigated in a 200-yr integration of a global model of the coupled oceanic and atmospheric general circulations developed at the Geophysical Fluid Dynamics Laboratory (GFDL). The second 100 yr of SST in the coupled model's tropical Atlantic region were analyzed with a variety of techniques. Analyses of SST time series, averaged over approximately the same subregions as the Global Ocean Surface Temperature Atlas (GOSTA) time series, showed that the GFDL SST anomalies also undergo pronounced quasi-oscillatory decadal and multidecadal variability but at somewhat shorter timescales than the GOSTA SST anomalies. Further analyses of the horizontal structures of the decadal timescale variability in the GFDL coupled model showed the existence of two types of variability in general agreement with results of the GOSTA SST time series analyses. One type, characterized by timescales between 8 and 11 yr, has high spatial coherence within each hemisphere but not between the two hemispheres of the tropical Atlantic. A second type, characterized by timescales between 12 and 20 yr, has high spatial coherence between the two hemispheres. The second type of variability is considerably weaker than the first. As in the GOSTA time series, the multidecadal variability in the GFDL SST time series has approximately opposite phases between the tropical North and South Atlantic Oceans. Empirical orthogonal function analyses of the tropical Atlantic SST anomalies revealed a north-south bipolar pattern as the dominant pattern of decadal variability. It is suggested that the bipolar pattern can be interpreted as decadal variability of the interhemispheric gradient of SST anomalies. The decadal and multidecadal timescale variability of the tropical Atlantic SST, both in the actual and in the GFDL model, stands out significantly above the background 'red noise' and is coherent within each of the time series, suggesting that specific sets of

  12. How does Atlantic Multi-decadal Overturning Circulation modulate Tropical circulation and preciptation responses to global warming ?

    Science.gov (United States)

    Vial, Jessica; Codron, Francis; Cassou, Christophe; Bony, Sandrine

    2017-04-01

    Tropical precipitation response to global warming remains highly uncertain. Most of the uncertainty is attributed to inter-model spread in atmospheric circulation changes. Model diversity in tropical circulation response has been traced further to differences in Tropical surface warming patterns, and in particular to the location of the maximum increase in the Equatorial Pacific. The involved mechanisms point to the importance of ocean-atmosphere interactions assessed through several process metrics. Here, we investigate the role of the Atlantic Multi-decadal Overturning Circulation (AMOC) in the response of the Tropical circulation to increased greenhouse gazes concentration. AMOC has been shown to affect the global Tropics, including the Equatorial surface warming pattern through atmospheric bridges across Central and/or North America. We use two ensembles of the coupled (ocean-atmosphere) CNRM-CM5 climate model that differ from their mean AMOC and apply an abrupt doubling CO2 concentration in both cases. Beyond the modulation role of AMOC in the Tropical circulation and precipitation changes, we show that AMOC has a potential effect on the estimation of the climate sensitivity of the model.

  13. Tropical Atlantic Dust and Smoke Aerosol Variabilities Related to the Madden-Julian Oscillation in MODIS and MISR Observations

    Science.gov (United States)

    Guo, Yanjuan; Tian, Baijun; Kahn, Ralph A.; Kalashnikova, Olga; Wong, Sun; Waliser, Duane E.

    2012-01-01

    In this study, MODIS fine mode fraction and MISR non-spherical fraction are 2used to derive dust and smoke AOT components (tau(sub dust) and tau(sub smoke)) over the tropical Atlantic, and their variabilities related to the Madden-Julian Oscillation (MJO) are then investigated. Both MODIS and MISR show a very similar dust and smoke winter climatology. tau(sub dust) is found to be the dominant aerosol component over the tropical Atlantic while tau(sub smoke) is significantly smaller than tau(sub dust). The daily MODIS and MISR tau(sub dust) are overall highly correlated, with the correlation coefficients typically about 0.7 over the North Atlantic. The consistency between the MODIS and MISR dust and smoke aerosol climatology and daily variations give us confidence to use these two data sets to investigate their relative contributions to the total AOT variation associated with the MJO. However, unlike the MISR dust discrimination, which is based on particle shape retrievals, the smoke discrimination is less certain, based on assumed partitioning of maritime aerosol for both MISR and MODIS. The temporal evolution and spatial patterns of the tau(sub dust) anomalies associated with the MJO are consistent between MODIS and MISR. The tau(sub dust) anomalies are very similar to those of tau anomalies, and are of comparable magnitude. In contrast, the MJO-related tau(sub smoke) anomalies are rather small, and the tau(sub mar) anomalies are negligible. The consistency between the MODIS and MISR results suggests that dust aerosol is the dominant component on the intra-seasonal time scale over the tropical Atlantic Ocean.

  14. Statistical Aspects of North Atlantic Basin Tropical Cyclones During the Weather Satellite Era, 1960-2013. Part 2

    Science.gov (United States)

    Wilson, Robert M.

    2014-01-01

    This Technical Publication (TP) is part 2 of a two-part study of the North Atlantic basin tropical cyclones that occurred during the weather satellite era, 1960-2013. In particular, this TP examines the inferred statistical relationships between 25 tropical cyclone parameters and 9 specific climate-related factors, including the (1) Oceanic Niño Index (ONI), (2) Southern Oscillation Index (SOI), (3) Atlantic Multidecadal Oscillation (AMO) index, (4) Quasi-Biennial Oscillation (QBO) index, (5) North Atlantic Oscillation (NAO) index of the Climate Prediction Center (CPC), (6) NAO index of the Climate Research Unit (CRU), (7) Armagh surface air temperature (ASAT), (8) Global Land-Ocean Temperature Index (GLOTI), and (9) Mauna Loa carbon dioxide (CO2) (MLCO2) index. Part 1 of this two-part study examined the statistical aspects of the 25 tropical cyclone parameters (e.g., frequencies, peak wind speed (PWS), accumulated cyclone energy (ACE), etc.) and provided the results of statistical testing (i.e., runs-testing, the t-statistic for independent samples, and Poisson distributions). Also, the study gave predictions for the frequencies of the number of tropical cyclones (NTC), number of hurricanes (NH), number of major hurricanes (NMH), and number of United States land-falling hurricanes (NUSLFH) expected for the 2014 season, based on the statistics of the overall interval 1960-2013, the subinterval 1995-2013, and whether the year 2014 would be either an El Niño year (ENY) or a non-El Niño year (NENY).

  15. Mammal occurrence and roadkill in two adjacent ecoregions (Atlantic Forest and Cerrado) in south-western Brazil

    OpenAIRE

    Cáceres, Nilton C.; Hannibal, Wellington; Freitas, Dirceu R.; Silva, Edson L.; Roman, Cassiano; Casella, Janaina

    2010-01-01

    This paper examines the frequencies of mammal roadkill in two adjacent biogeographic ecoregions (Atlantic Forest and Cerrado) of Brazil. Mammals were recorded during a seven-year period and over 3,900 km of roads, in order to obtain data for frequencies of species in habitats (sites) and frequencies of species killed by cars on roads. Sites (n = 80) within ecoregions (Cerrado, n = 57; Atlantic Forest, n = 23) were searched for records of mammals. Species surveyed in the entire region totaled ...

  16. Statistical Aspects of North Atlantic Basin Tropical Cyclones During the Weather Satellite Era, 1960-2013: Part 1

    Science.gov (United States)

    Wilson, Robert M.

    2014-01-01

    A tropical cyclone is described as a warm-core, nonfrontal, synoptic-scale system that originates over tropical or subtropical waters, having organized deep convection and closed surface wind circulation (counterclockwise in the Northern Hemisphere) about a well defined center. When its sustained wind speed equals 34-63 kt, it is called a tropical (or subtropical) storm and is given a name (i.e., alternating male and female names, beginning in 1979); when its sustained wind speed equals 64-95 kt, it is called a hurricane (at least in the Eastern Pacific and North Atlantic basin); and when its sustained wind speed equals 96 kt or higher, it is called an intense or major hurricane (i.e., categories 3-5 on the Saffir-Simpson Hurricane Wind Scale). Although tropical cyclones have been reported and described since the voyages of Columbus, a detailed record of their occurrences extends only from 1851 to the present, with the most reliable portion extending only from about 1945 to the present, owing to the use of near-continuous routine reconnaissance aircraft monitoring flights and the use of satellite imagery (beginning in 1960; see Davis). Even so, the record may still be incomplete, possibly missing at least one tropical cyclone per yearly hurricane season, especially prior to the use of continuous satellite monitoring. In fact, often an unnamed tropical cyclone is included in the year-end listing of events at the conclusion of the season, following post-season analysis (e.g., as happened in 2011 and 2013, each having one unnamed event). In this two-part Technical Publication (TP), statistical aspects of the North Atlantic basin tropical cyclones are examined for the interval 1960-2013, the weather satellite era. Part 1 examines some 25 parameters of tropical cyclones (e.g., frequencies, peak wind speed (PWS), accumulated cyclone energy (ACE), etc.), while part 2 examines the relationship of these parameters against specific climate-related factors. These studies are

  17. North Atlantic Tropical Cyclone Activity over the last 2000 years: Patterns, Consequences and Potential Climatic Forcing

    Science.gov (United States)

    Donnelly, J. P.; Lane, P.; Hawkes, A.; van Hengstum, P. J.; Ranasinghe, P. N.; Toomey, M.; MacDonald, D.

    2011-12-01

    With a series of high-resolution reconstructions of hurricane-induced overwash from high deposition rate sites from across the western North Atlantic, we document patterns of event occurrence dating back more than 2000 years. Some sites with interbedded overwash sediments preserve annual laminations, which provide exceptional chronologies of hurricanes. The records suggest that while the frequency of hurricane landfall in the region has not changed dramatically over the last two millennia, the frequency of intense hurricanes has varied considerably. Sedimentary evidence suggests the eastern seaboard of the United States experienced a period of elevated intense hurricane activity during the 15th, 16th and early 17th Centuries. Spanish document archives also suggest elevated tropical cyclone activity during the late 16th and early 17th Centuries. This interval of increased intense hurricane activity had significant impacts on coastal landforms and ecosystems including more frequent and widespread inlet formation, erosion of coastal wetlands, and forest disturbance. Similarly, an earlier active interval between 2500 and 1000 years ago may have had a dramatic impact on coastal pine and scrub oak forests in the northeastern United States. Pollen and charcoal analyses indicate more frequent forest disturbance with the highest concentration of charcoal occurring during the active period between 1900 and 1300 years ago. Many of the peaks in charcoal follow closely after storm-induced coarse grained deposits. The increase of large fires during the active hurricane regime between 1900 and 1300 years ago provides compelling evidence of hurricane/fire interactions. However drought, identified by a lake level lowstand in the region, may have contributed to increased fires during this interval. Fossil pollen preserved in the sediment provides evidence of significant changes in vegetation composition in most taxonomic groups during the active hurricane interval between 1900 and

  18. Long term Changes in Flooding and Heavy Rainfall Associated with North Atlantic Tropical Cyclones

    Science.gov (United States)

    Aryal, Y.; Villarini, G.; Zhang, W.; Vecchi, G. A.

    2016-12-01

    Flooding associated with North Atlantic tropical cyclones (TCs) are one of the costliest weather disasters in the continental United States, claiming a large toll in terms of fatalities and economic damage. Despite these large impacts, very little attention has been paid to the temporal changes in TC-flood hazard and to the possible connections with climate. In this study, we focus on long-term U.S. Geological Survey (USGS) stream gages with at least 50 years of data ending no earlier than 2010 and located over most of the continental United States, east of the Rocky Mountains. Analyses are based on annual maxima (AMs) and Peaks-Over-Threshold (POTs). We associate a flood peak to a TC if the stream gage is located within 500 km from the center of circulation of the storms and it happens within a time window of seven days. Moreover, to account for potential non stationarities in the flood peak records and for differences due to drainage area, we compute the flood ratio, defined as the ratio between the TC-flood and the 2-year flood peak computed with respect to moving ten-year time window. We find that TCs contribute to large fractions of AMs and POTs over Florida ( 30-40%), with their influence that decreases as we move inland. We do not detect statistically significant increasing or decreasing trends in flood ratio or in the frequency of TC floods. Beside the examination of temporal changes in TC-flooding, we also examine the role played by the North Atlantic Oscillation (NAO) and El Niño - Southern Oscillation (ENSO) in controlling the frequency and magnitude of these events. Overall, TC floods tend to be more likely during the negative phase of NAO. On the other hand, the effects of ENSO tend to vary in space. Overall, NAO and ENSO do not seem to play a large role in controlling the frequency and magnitude of TC flooding. Similar analyses will be performed using TC-rainfall, comparing and contrasting what found for TC-flooding.

  19. Gigantic oocytes in the deep sea black coral Dendrobathypathes grandis (Antipatharia) from the Mar del Plata submarine canyon area (southwestern Atlantic)

    Science.gov (United States)

    Lauretta, Daniel; Penchaszadeh, Pablo E.

    2017-10-01

    The black coral Dendrobathypathes grandis (Cnidaria: Antipatharia) is studied for the first time in the southwestern Atlantic off Argentina. This is the only antipatharian reported from the Atlantic between 35°S and 54°S. Eleven specimens were collected at depths of 819-2204 m during three expeditions to the Mar del Plata submarine canyon (2012-2013); seven were females. The species is gonochoric, and the polyps in female colonies contain up to nine oocytes per polyp, which can reach 1500 μm in diameter. In contrast, the largest oocyte currently reported for antipatharians is 500 μm, and usual diameters do not exceed 200 μm. These large oocytes have over 20 times more volume than the biggest oocyte reported, but over 800 times more volume when compared with the common oocyte size of the group. Sperm size and morphology is similar to previous data from other species. As in previous studies, neither embryos nor larvae were found in any specimens. This species was previously only reported from waters off South Georgia Island, and so these specimens expand the known distribution north by 1800 km.

  20. Enhanced Influence of the Tropical Atlantic SST on the Western North Pacific Subtropical High after late 1970s

    Science.gov (United States)

    Hong, C. C.

    2015-12-01

    The western North Pacific subtropical high (WNPSH) in boreal summer shows a remarkable enhancement after the late 1970s. Whereas the sea surface temperature (SST) in the North Indian Ocean (NIO) and the equatorial eastern Pacific (EEP) had been noted to have remarkable local or remote effects on enhancing the WNPSH, the influence of the Atlantic SST, so far, is hardly explored. This article reports a new finding: enhanced relationship between the tropical Atlantic (TA)-SST and the WNPSH after the late 1970s. Regression study suggests that the warm TA-SST produced a zonally overturning circulation anomaly, with descending over the central equatorial Pacific and ascending over the tropical Atlantic/eastern Pacific. The anomalous descending over the central equatorial Pacific likely induced low-level anticyclonic anomaly to the west and therefore enhanced the WNPSH. One implication of this new finding is for predictability. The well-known "spring predictability barrier" (i.e., the influence of El Niño and Southern Oscillation (ENSO) falls dramatically during boreal spring) does not apply to the TA-SST/WNPSH relationship. Conversely, the TA-SST shows consistently high correlation starting from boreal spring when the ENSO influence continues declining. The TA-SST pushes the predictability of the WNPSH in boreal summer approximately one season earlier to boreal spring.

  1. Mesozooplankton Graze on Cyanobacteria in the Amazon River Plume and Western Tropical North Atlantic.

    Science.gov (United States)

    Conroy, Brandon J; Steinberg, Deborah K; Song, Bongkuen; Kalmbach, Andrew; Carpenter, Edward J; Foster, Rachel A

    2017-01-01

    Diazotrophic cyanobacteria, those capable of fixing di-nitrogen (N 2 ), are considered one of the major sources of new nitrogen (N) in the oligotrophic tropical ocean, but direct incorporation of diazotrophic N into food webs has not been fully examined. In the Amazon River-influenced western tropical North Atlantic (WTNA), diatom diazotroph associations (DDAs) and the filamentous colonial diazotrophs Trichodesmium have seasonally high abundances. We sampled epipelagic mesozooplankton in the Amazon River plume and WTNA in May-June 2010 to investigate direct grazing by mesozooplankton on two DDA populations: Richelia associated with Rhizosolenia diatoms (het-1) and Hemiaulus diatoms (het-2), and on Trichodesmium using highly specific qPCR assays targeting nitrogenase genes ( nifH ). Both DDAs and Trichodesmium occurred in zooplankton gut contents, with higher detection of het-2 predominantly in calanoid copepods (2.33-16.76 nifH copies organism -1 ). Abundance of Trichodesmium was low (2.21-4.03 nifH copies organism -1 ), but they were consistently detected at high salinity stations (>35) in calanoid copepods. This suggests direct grazing on DDAs, Trichodesmium filaments and colonies, or consumption as part of sinking aggregates, is common. In parallel with the qPCR approach, a next generation sequencing analysis of 16S rRNA genes identified that cyanobacterial assemblage associated with zooplankton guts was dominated by the non-diazotrophic unicellular phylotypes Synechococcus (56%) and Prochlorococcus (26%). However, in two separate calanoid copepod samples, two unicellular diazotrophs Candidatus Atelocyanobacterium thalassa (UCYN-A) and Crocosphaera watsonii (UCYN-B) were present, respectively, as a small component of cyanobacterial assemblages (<2%). This study represents the first evidence of consumption of DDAs, Trichodesmium , and unicellular cyanobacteria by calanoid copepods in an area of the WTNA known for high carbon export. These diazotroph populations

  2. Unravelling the Natural and Anthropogenic Drivers of North Atlantic Tropical Cyclone Track Position since the Little Ice Age

    Science.gov (United States)

    Baldini, L. M.; Baldini, J. U. L.; McElwaine, J.; Frappier, A. B.; Asmerom, Y.; Liu, K. B.; Prufer, K. M.; Ridley, H.; Polyak, V. J.; Kennett, D. J.; Macpherson, C.; Aquino, V. V.; Awe, J.; Breitenbach, S. F. M.

    2017-12-01

    In the last decade, stalagmites have been recognised as valuable archives of past hurricane activity. The characteristically low δ18O rainfall of tropical cyclones (TCs, including both hurricanes and tropical storms) is particularly well-preserved in fast-growing tropical speleothems. Here we present a new multi-proxy approach used to extract the western Caribbean TC signal from background wet season rainfall that, at our site in southern Belize, is driven by seasonal migration of the Intertropical Convergence Zone (ITCZ). The result is an annual 450-year record of western Caribbean TC activity that, when compared to documentary and statistical model-based reconstructions of North Atlantic TC activity, reveals a northward migration of dominant TC track since the height of Little Ice Age cooling. Importantly, the record reveals a reversal in the TC track position-North Atlantic sea surface temperature relationship between the pre-Industrial and Industrial Eras. During the pre-Industrial interval, TC track position migrated with the ITCZ toward the warmer hemisphere. Conversely, anthropogenic greenhouse gas and aerosol emissions during the Industrial Era have decoupled TC track position from the ITCZ through expansion of the Hadley Cell. This research suggests that under future greenhouse gas and aerosol emissions scenarios, the dominant TC track is likely to remain to the north. Combined with greenhouse gas-induced rising sea surface temperatures, the risk to the NE US population and financial centres is likely to increase in the future.

  3. Bias for summer decay of interannual SST anomaly in the northern tropical Atlantic and its link with the Guinea Dome in coupled GCMs

    Science.gov (United States)

    Doi, T.; Vecchi, G. A.

    2010-12-01

    Interannual sea surface temperature (SST) anomaly in the northern topical Atlantic is strongly seasonally phase-locked; it develops from early winter, reaches the peak in spring, and decays suddenly in summer. To simulate this seasonal phase-locking reasonably is critical for the accurate prediction of the Atlantic hurricane activity. In a fully coupled ocean-atmosphere model of GFDL-CM2.1 (Climate Model version 2.1 developed at the Geophysical Fluid Dynamics Laboratory), the decay of SSTA in the northern tropical Atlantic is slower and weaker than the observation. This bias is amplified and sustained by a false air-sea coupled positive feedback linked with the subsurface doming of thermocline in the northeastern tropical Atlantic: the Guinea Dome. Anomalous northward migration of the ITCZ associated with the warm SST anomaly in the northern tropical Atlantic leads to the stronger Ekman upwelling and colder subsurface temperature in the north of the climatological Guinea Dome region, where the doming and entrainment is relatively weak in the climatology. Therefore, the cold subsurface Guinea Dome cannot work on the decay of warm SST anomaly through entrainment. In contrast, the warmer subsurface temperature is found just in the climatological Guinea Dome region. It suppresses the decay of the warm SST anomaly through entrainment. The outcome is the sustained warm SST anomaly during summer and further northward ITCZ migration. Therefore, realistic simulation of the subsurface Guinea Dome is critical for improving the seasonal phase-locking bias in the northern tropical Atlantic.

  4. The distribution of thiamin and pyridoxine in the western tropical North Atlantic Amazon River plume

    Directory of Open Access Journals (Sweden)

    Laila Pualani Barada

    2013-03-01

    Full Text Available B-vitamins are recognized as essential organic growth factors for many organisms, although little is known about their abundance and distribution in marine ecosystems. Despite their metabolic functions regulating important enzymatic reactions, the methodology to directly measure different B-vitamins in aquatic environments has only recently been developed. Here, we present the first direct measurements of two B-vitamins, thiamin (B1 and pyridoxine (B6, in the Amazon River plume-influenced Western Tropical North Atlantic (WTNA Ocean, an area known to have high productivity, carbon (C and dinitrogen (N2 fixation, and C sequestration. The vitamins B1 and B6 ranged in concentrations from undetectable to 230 pM and 40 pM, respectively. Significantly higher concentrations were measured in the surface plume water at some stations and variation with salinity was observed, suggesting a possible riverine influence on those B-vitamins. The influences of vitamins B1 and B6 on biogeochemical processes such as C and N2 fixation were investigated using a linear-regression model that indicated that the availability of those organic factors could affect these rates in the WTNA. In fact, significant increases in C fixation and N2 fixation were observed with increasing vitamin B1 concentrations at some low and mesohaline stations (stations 9.1 and 1; p value <0.017 and <0.03, respectively. N2 fixation was also found to have a significant positive correlation with B1 concentrations at station 1 (p value = 0.029, as well as vitamin B6 at station 9.1 (p value <0.017. This work suggests that there can be a dynamic interplay between essential biogeochemical rates (C and N2 fixation and B-vitamins, drawing attention to potential roles of B-vitamins in ecosystem dynamics, community structure, and global biogeochemistry.

  5. Grazing by Zooplankton on Diazotrophs in the Amazon River Plume and Western Tropical North Atlantic

    Science.gov (United States)

    Conroy, B.; Steinberg, D. K.; Song, B.; Foster, R.

    2016-02-01

    Organisms capable of fixing di-nitrogen (N2), known as diazotrophs, are important primary producers and a potentially significant source for new nitrogen entering the planktonic food web. However, limited evidence exists for zooplankton grazing on diazotrophs compared to other primary producers. In the western tropical North Atlantic Ocean (WTNA), the Amazon River plume creates a niche for symbiotic diatom-diazotroph associations (DDAs) which can form large blooms. In adjacent non-plume-influenced waters, the colonial cyanobacterium Trichodesmium is abundant. In order to reveal zooplankton-diazotroph grazing interactions and determine the fate of newly fixed nitrogen, gut contents of zooplankton captured in these two regions were compared based on quantitative PCR (qPCR) assay of nitrogenase genes (nifH), and their microbiomes compared using next generation sequencing (NGS) analysis of 16S rRNA genes. We sampled individual copepods from discrete depth intervals (0-25m and 25-50m) and in two size classes (0.5-1mm and 1-2mm) for analysis. A modified DNA extraction protocol was developed and 54 extracts were used as templates in nifH qPCR assays for the larger size fraction diazotrophs (>10µm): Trichodesmium, and Hemiaulus or Rhizosolenia (diatoms)-Richelia (diazotroph) associations. Copepod gut content nifH copies ranged from 1.6 to 13.6 copies individual-1 for the assay targeting the Hemiaulus-Richelia DDA and from 1.1 to 3.0 copies individual-1 for Trichodesmium. 16S NGS conducted on 35 extracts with an Ion Torrent PGM and mothur revealed that cyanobacteria sequences accounted for up to 20% of sequences per extract. Our results show that both DDAs and Trichodesmium are prey for zooplankton, and that new nitrogen moves through the food web via these grazing interactions. These interactions should be considered in future explorations of the global ocean nitrogen cycle.

  6. The Teleconnection of the Tropical Atlantic to Indo-Pacific Sea Surface Temperatures on Inter-Annual to Centennial Time Scales: A Review of Recent Findings

    Directory of Open Access Journals (Sweden)

    Fred Kucharski

    2016-02-01

    Full Text Available In this paper, the teleconnections from the tropical Atlantic to the Indo-Pacific region from inter-annual to centennial time scales will be reviewed. Identified teleconnections and hypotheses on mechanisms at work are reviewed and further explored in a century-long pacemaker coupled ocean-atmosphere simulation ensemble. There is a substantial impact of the tropical Atlantic on the Pacific region at inter-annual time scales. An Atlantic Niño (Niña event leads to rising (sinking motion in the Atlantic region, which is compensated by sinking (rising motion in the central-western Pacific. The sinking (rising motion in the central-western Pacific induces easterly (westerly surface wind anomalies just to the west, which alter the thermocline. These perturbations propagate eastward as upwelling (downwelling Kelvin-waves, where they increase the probability for a La Niña (El Niño event. Moreover, tropical North Atlantic sea surface temperature anomalies are also able to lead La Niña/El Niño development. At multidecadal time scales, a positive (negative Atlantic Multidecadal Oscillation leads to a cooling (warming of the eastern Pacific and a warming (cooling of the western Pacific and Indian Ocean regions. The physical mechanism for this impact is similar to that at inter-annual time scales. At centennial time scales, the Atlantic warming induces a substantial reduction of the eastern Pacific warming even under CO2 increase and to a strong subsurface cooling.

  7. Are mangroves in the tropical Atlantic ripe for invasion? Exotic mangrove trees in the forests of South Florida

    Science.gov (United States)

    Fourqurean, James W.; Smith, Thomas J.; Possley, Jennifer; Collins, Timothy M.; Lee, David; Namoff, Sandra

    2010-01-01

    Two species of mangrove trees of Indo-Pacific origin have naturalized in tropical Atlantic mangrove forests in South Florida after they were planted and nurtured in botanic gardens. Two Bruguiera gymnorrhiza trees that were planted in the intertidal zone in 1940 have given rise to a population of at least 86 trees growing interspersed with native mangrove species Rhizophora mangle, Avicennia germinans and Laguncularia racemosa along 100 m of shoreline; the population is expanding at a rate of 5.6% year−1. Molecular genetic analyses confirm very low genetic diversity, as expected from a population founded by two individuals. The maximum number of alleles at any locus was three, and we measured reduced heterozygosity compared to native-range populations. Lumnitzera racemosa was introduced multiple times during the 1960s and 1970s, it has spread rapidly into a forest composed of native R. mangle, A. germinans, Laguncularia racemosa and Conocarpus erectus and now occupies 60,500 m2 of mangrove forest with stem densities of 24,735 ha−1. We estimate the population growth rate of Lumnitzera racemosa to be between 17 and 23% year−1. Populations of both species of naturalized mangroves are dominated by young individuals. Given the long life and water-dispersed nature of propagules of the two exotic species, it is likely that they have spread beyond our survey area. We argue that the species-depauperate nature of tropical Atlantic mangrove forests and close taxonomic relatives in the more species-rich Indo-Pacific region result in the susceptibility of tropical Atlantic mangrove forests to invasion by Indo-Pacific mangrove species.

  8. Oxygen variability and meridional oxygen supply in the tropical North East Atlantic oxygen minimum zone

    Science.gov (United States)

    Hahn, Johannes; Brandt, Peter; Greatbatch, Richard J.; Krahmann, Gerd; Körtzinger, Arne

    2013-04-01

    The oxygen minimum zone (OMZ) of the tropical North East Atlantic (TNEA) is located between the oxygen-rich equatorial region and the Cape Verde Frontal Zone at about 20°N in a depth range of 300 - 700 m. Its horizontal extent is predominantly defined by the North Equatorial Current and by the equatorial zonal current system ventilating the region to the north and south of the OMZ, respectively. The interior of the OMZ is characterized by a sluggish flow regime, where mesoscale eddies play a major role in the ventilation. In this study we focus on the oxygen variability in the TNEA as well as the eddy driven lateral ventilation of the TNEA OMZ across its southern boundary. During recent years an intense measurement program was executed along 23°W cutting meridionally through the TNEA OMZ. Hydrographic and velocity data has been acquired from ship sections and moorings, together covering the latitude range between 6°S and 14°N with particularly high meridional resolution of shipboard and high temporal resolution of moored observations. Based on shipboard data we derived a meridional section of oxygen variance, which reveals numerous local maxima of oxygen variability. Exemplary, strong oxygen variability is observed at the upper (300m, 5° - 12°N) and the southern boundary (400m - 700m, 5°N - 8°N) of the OMZ, whereas the interior of the OMZ is characterized by weak variability. An application of the extended Osborn-Cox model shows that the strong oxygen variability at the southern boundary is mainly generated by mesoscale eddies. The strong variability at the upper boundary is generated by mesoscale eddies as well as microscale turbulence. We apply two methods to estimate the meridional oxygen flux: 1) a flux gradient parameterization and 2) a correlation of oxygen and velocity mooring time series. From the analysis of the 5°N mooring data we find a northward oxygen flux directed towards the OMZ at its core depth, that is mainly due to variability of

  9. Forage fauna in the diet of bigeye tuna (Thunnus obesus in the western tropical Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Teodoro Vaske Júnior

    2012-03-01

    Full Text Available A total of 291 stomachs of bigeye tuna caught in the Western tropical Atlantic Ocean ranging between 60 and 195 cm fork length, were analyzed between October 2004 and November 2005. The vertical distribution of prey was studied in relation to their feeding strategies. A total of 83 prey items were identified of which 46 were fishes, represented mainly by brephoepipelagic, and meso-bathypelagic fishes; 20 cephalopods, 13 pelagic crustaceans, one tunicate, one heteropod and one pteropod. The Caribbean pomfret Brama caribbea was the most important food item, followed by other mesopelagic fishes such as Alepisaurus ferox, Omosudis lowei, Gempylus serpens, Brama brama and Diretmus argenteus. The squid Ornithoteuthis antillarum was the main preyed-on cephalopod, and the crustaceans Caridea and Brachyuran megalopae were also important food items. The feeding may occur continuously, all the time, or at least during the greater part of the day or night, as part of the feeding strategy to prey upon a vertically scattered small prey distributed in the water column. The relative equality in the proportions of surface, mid-water and deep-water prey organisms reflects the behavior of constant vertical displacement in the search for prey. Although the bigeye tuna prefers subthermocline layers, most of its prey items perform diel migrations and can be preyed on both near the surface and in deeper waters.Um total de 291 estômagos de albacoras-bandolins capturadas no oceano Atlântico tropical oeste variando entre 60 e 195 cm de comprimento furcal, foram analisados entre outubro de 2004 e dezembro de 2005. A distribuição vertical das presas foi estudada em relação às estratégias alimentares. Um total de 83 itens alimentares foi identificado dos quais 46 foram peixes representados principalmente por peixes brefoepipelágicos e mesopelágicos, 20 cefalópodes, 13 crustáceos pelágicos, um tunicado, um heterópode e um pterópode. A palombeta

  10. Long term changes in flooding and heavy rainfall associated with North Atlantic tropical cyclones: Roles of the North Atlantic Oscillation and El Niño-Southern Oscillation

    Science.gov (United States)

    Aryal, Yog N.; Villarini, Gabriele; Zhang, Wei; Vecchi, Gabriel A.

    2018-04-01

    The aim of this study is to examine the contribution of North Atlantic tropical cyclones (TCs) to flooding and heavy rainfall across the continental United States. Analyses highlight the spatial variability in these hazards, their temporal changes in terms of frequency and magnitude, and their connection to large-scale climate, in particular to the North Atlantic Oscillation (NAO) and El Niño-Southern Oscillation (ENSO). We use long-term stream and rain gage measurements, and our analyses are based on annual maxima (AMs) and peaks-over-threshold (POTs). TCs contribute to ∼20-30% of AMs and POTs over Florida and coastal areas of the eastern United States, and the contribution decreases as we move inland. We do not detect statistically significant trends in the magnitude or frequency of TC floods. Regarding the role of climate, NAO and ENSO do not play a large role in controlling the frequency and magnitude of TC flooding. The connection between heavy rainfall and TCs is comparable to what observed in terms of flooding. Unlike flooding, NAO plays a significant role in TC-related extreme rainfall along the U.S. East Coast, while ENSO is most strongly linked to the TC precipitation in Texas.

  11. Shipboard and Satellite Views of Elevated Tropospheric Ozone over the Tropical Atlantic in January-February 1999

    Science.gov (United States)

    Thompson, Anne M.; Doddridge, Bruce G.; Hudson, Robert D.; Witte, Jacquelyn C.; Luke, Winston T.; Johnson, James E.; Johnson, Bryan J.; Oltmans, Samuel J.

    1999-01-01

    During the Aerosols99 trans-Atlantic cruise from Norfolk, VA, to Cape Town, South Africa, daily ozonesondes were launched from the NOAA R/V Ronald H Brown between 17 January and 6 February l999. A composite of tropospheric ozone profiles along the latitudinal transect shows 4 zones, which are interpreted using correlative shipboard ozone, CO, water vapor, and overhead aerosol optical thickness measurements. Elevated ozone associated with biomass burning north of the ITCZ (Intertropical Convergence Zone) is prominent at 3-5 km from 10-0N, but even higher ozone (100 ppbv, 7-10 km) occurred south of the ITCZ, where it was not burning. Column-integrated tropospheric ozone was 44 Dobson Units (DU) in one sounding, 10 DU lower than the maximum in a January-February 1993 Atlantic cruise with ozonesondes [Weller et al., 1996]. TOMS tropospheric ozone shows elevated ozone extending throughout the tropical Atlantic in January 1999. Several explanations are considered. Back trajectories, satellite aerosol observations and shipboard tracers suggest a combination of convection and interhemispheric transport of ozone and/or ozone precursors, probably amplified by a lightning NO source over Africa.

  12. Use of otolith strontium:calcium and zinc:calcium ratios as an indicator of the habitat of Percophis brasiliensis Quoy & Gaimard, 1825 in the southwestern Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Esteban Avigliano

    Full Text Available We evaluate the simultaneous use of Sr: Ca and Zn: Ca ratios of the sagitta otolith as a potential indicator of the habitat of Percophis brasiliensis along a latitudinal gradient in the southwestern Atlantic Ocean (34-42ºS and 51-67ºW, in order to reliably identify fish stocks. Fish were collected in three sampling sites: Argentine-Uruguayan Common Fishing Zone (AUCFZ, El Rincón (ER and San Matías Gulf (SMG. The otolith Sr:Ca and Zn:Ca ratios were determined by ICP-OES and EDTA volumetric method. The otolith Sr:Ca ratio was similar in the three sampling sites, while the Zn:Ca ratio was significantly higher in AUCFZ than in ER and SMG for all age groups. The discriminant analysis showed an association between the otolith Sr:Ca and Zn:Ca ratios from ER and SMG. Present results suggest the potential occurrence of two fish stocks of P. brasiliensis in the study area.

  13. Marine debris in beaches of the Southwestern Atlantic: An assessment of their abundance and mass at different spatial scales in northern coastal Argentina.

    Science.gov (United States)

    Becherucci, Maria Eugenia; Rosenthal, Alan Federico; Seco Pon, Juan Pablo

    2017-06-15

    Argentina is currently undergoing an intensive development of coastal-oriented tourism due to the temperate climate and coastal sceneries of the Southwestern Atlantic and particularly its wide ocean-open sandy beaches, which may turn into an important contributor of marine debris to the beaches. This study was designed to assess at four spatial scales (i) the variation of the abundance and mass of marine debris and (ii) the composition and sources of these items in sandy-tourist beaches of coastal zones of the province of Buenos Aires, in northern Argentina. The abundance and mass of marine debris shifted between sampling localities (separated by ~1.5×10 5 m) and beaches (~3×10 4 m). Debris was primarily from recreational and fishing activities and over 20mm in size. Tackling the complications associated with marine debris in northern Argentina may include intensive educational and advertising campaigns oriented chiefly to beach users and fisherman. Copyright © 2017. Published by Elsevier Ltd.

  14. The tropical Atlantic surface wind divergence belt and its effect on clouds

    OpenAIRE

    Y. Tubul; I. Koren; O. Altaratz

    2015-01-01

    A well-defined surface wind divergence (SWD) belt with distinct cloud properties forms over the equatorial Atlantic during the boreal summer months. This belt separates the deep convective clouds of the Intertropical Convergence Zone (ITCZ) from the shallow marine stratocumulus cloud decks forming over the cold-water subtropical region of the southern branch of the Hadley cell in the Atlantic. Using the QuikSCAT-SeaWinds and Aqua-MODIS instruments, we examined the large-scal...

  15. Tropical Dominance of N2 Fixation in the North Atlantic Ocean

    Science.gov (United States)

    Marconi, Dario; Sigman, Daniel M.; Casciotti, Karen L.; Campbell, Ethan C.; Alexandra Weigand, M.; Fawcett, Sarah E.; Knapp, Angela N.; Rafter, Patrick A.; Ward, Bess B.; Haug, Gerald H.

    2017-10-01

    To investigate the controls on N2 fixation and the role of the Atlantic in the global ocean's fixed nitrogen (N) budget, Atlantic N2 fixation is calculated by combining meridional nitrate fluxes across World Ocean Circulation Experiment sections with observed nitrate 15N/14N differences between northward and southward transported nitrate. N2 fixation inputs of 27.1 ± 4.3 Tg N/yr and 3.0 ± 0.5 Tg N/yr are estimated north of 11°S and 24°N, respectively. That is, 90% of the N2 fixation in the Atlantic north of 11°S occurs south of 24°N in a region with upwelling that imports phosphorus (P) in excess of N relative to phytoplankton requirements. This suggests that, under the modern iron-rich conditions of the equatorial and North Atlantic, N2 fixation occurs predominantly in response to P-bearing, N-poor conditions. We estimate a N2 fixation rate of 30.5 ± 4.9 Tg N/yr north of 30°S, implying only 3 Tg N/yr between 30° and 11°S, despite evidence of P-bearing, N-poor surface waters in this region as well; this is consistent with iron limitation of N2 fixation in the South Atlantic. Since the ocean flows through the Atlantic surface in Pacific basins.

  16. Seabirds indicate changes in the composition of plastic litter in the Atlantic and south-western Indian Oceans.

    Science.gov (United States)

    Ryan, Peter G

    2008-08-01

    I compare plastic ingested by five species of seabirds sampled in the 1980s and again in 1999-2006. The numbers of ingested plastic particles have not changed significantly, but the proportion of virgin pellets has decreased 44-79% in all five species: great shearwater Puffinus gravis, white-chinned petrel Procellaria aequinoctialis, broad-billed prion Pachyptila vittata, white-faced storm petrel Pelagodroma marina and white-bellied storm petrel Fregetta grallaria. The populations sampled range widely in the South Atlantic and western Indian Oceans. The most marked reduction occurred in great shearwaters, where the average number of pellets per bird decreased from 10.5 to 1.6. This species migrates between the South and North Atlantic each year. Similar decreases in virgin pellets have been recorded in short-tailed shearwaters Puffinus tenuirostris in the Pacific Ocean and northern fulmars Fulmarus glacialis in the North Sea. More data are needed on the relationship between plastic loads in seabirds and the density of plastic at sea in their foraging areas, but the consistent decrease in pellets in birds suggests there has been a global change in the composition of small plastic debris at sea over the last two decades.

  17. Analysis of North Atlantic Tropical Cyclone Intensify Change Using Data Mining

    Science.gov (United States)

    Tang, Jiang

    2010-01-01

    Tropical cyclones (TC), especially when their intensity reaches hurricane scale, can become a costly natural hazard. Accurate prediction of tropical cyclone intensity is very difficult because of inadequate observations on TC structures, poor understanding of physical processes, coarse model resolution and inaccurate initial conditions, etc. This…

  18. Chemistry, transport and dry deposition of trace gases in the boundary layer over the tropical Atlantic Ocean and the Guyanas during the GABRIEL field campaign

    NARCIS (Netherlands)

    Stickler, A.; Fischer, H.; Bozem, H.; Gurk, C.; Schiller, C.; Martinez-Harder, M.; Kubistin, D.; Harder, H.; Williams, J.; Eerdekens, G.; Yassaa, N.; Ganzeveld, L.N.; Sander, R.; Lelieveld, J.

    2007-01-01

    We present a comparison of different Lagrangian and chemical box model calculations with measurement data obtained during the GABRIEL campaign over the tropical Atlantic Ocean and the Amazon rainforest in the Guyanas, October 2005. Lagrangian modelling of boundary layer (BL) air constrained by

  19. Tropospheric ozone over a tropical Atlantic station in the Northern Hemisphere: Paramaribo, Surinam (6°N, 55°W)

    NARCIS (Netherlands)

    Peters, W.; Krol, M. C.; Fortuin, J. P. F.; Kelder, H. M.; Thompson, A. M.; Becker, C. R.; Lelieveld, J.; Crutzen, P. J.

    2004-01-01

    We present an analysis of 2.5 yr of weekly ozone soundings conducted at a new monitoring station in Paramaribo, Surinam (6°N, 55°W). This is currently one of only three ozone sounding stations in the Northern Hemisphere (NH) tropics, and the only one in the equatorial Atlantic region. Paramaribo is

  20. Ethnomedicinal survey of a maroon community in Brazil's Atlantic tropical forest.

    Science.gov (United States)

    de Santana, Bruna Farias; Voeks, Robert A; Funch, Ligia Silveira

    2016-04-02

    Considerable medicinal plant research in Brazil has focused on indigenous and mixed-race (caboclo and caiçara) communities, but relatively few studies have examined the medicinal plants and associated healing traditions of the descendants of enslaved Africans. This study surveyed the medicinal plants employed by a relatively isolated maroon community of Afro-Brazilians in the Atlantic coastal rainforests of Bahia, Brazil, a global biodiversity hotspot. The studied community is exceptional in that the residents were defacto slaves until several years ago, with no access to western medicine. We examined the following questions: 1) What medicinal plants are used in this community? 2) What are the principal taxonomic groups, life forms, source habitats, and geographical origins? 3) What species stand out as measured by use value and frequency indices? and 4) Is the community's geographical isolation and African ancestry reflected in their medicinal uses of the local flora? The study was carried out in the Quilombo Salamina Putumuju maroon community in Bahia, Brazil. Data were collected from May to October 2014 from 74 individuals (37 men and 37 women) by means of semi-structured interviews, walk in the woods, and vouchering of identified species. We used the Cultural Value Index (CV), the Relative Frequency Index (RF), and the Use Value Index (UV) to determine the importance of medicinal plant resources. Continuity of African medicinal plant uses and traditions was determined through self-reporting and comparison with previously published works. We recorded 118 medicinal plant species distributed in 100 genera and 51 families. The best represented families were: Asteraceae, Fabaceae, Lamiaceae and Myrtaceae. Most plant medicines were used to treat respiratory, digestive systems, genitourinary, and skin problems. The most common medicinal life form was herbs (44%), followed by trees (28%) and shrubs (18%). Native species (55%) were used somewhat more than exotic

  1. Aerosol size-resolved trace metal composition in remote northern tropical Atlantic marine environment: case study Cape Verde islands

    Science.gov (United States)

    Fomba, K. W.; Müller, K.; van Pinxteren, D.; Herrmann, H.

    2013-05-01

    Size-resolved trace metal concentrations of 15 elements in aerosol particles at the Cape Verde Atmospheric Observatory (CVAO) under remote background conditions were investigated through analysis of aerosol samples collected during intensive field studies from January 2007 to November 2011 using total reflection x-ray fluorescence (TXRF). The identification of the main air mass origin that influence remote marine aerosol in the northern tropical Atlantic has been investigated. In total, 317 samples were collected. The dataset was analyzed according to the main air mass inflow at the station. We found that remote conditions make up about 45% of the meteorological conditions in a year at CVAO and thus the northern tropical Atlantic. Surprisingly, air masses from North America are often responsible for higher trace metal concentrations in this region. Elements such as Zn, Pb, Cu, Cr, Ni, and V were mostly found in the submicron size fractions, while elements with dominant crustal or oceanic origin such as Fe, Ti, Mn, Sr, and Rb were found in the coarse fractions (>1 μm). The highest metal concentrations, especially for Zn (3.23 ng m-3), Cu (0.81 ng m-3), Sr (2.63 ng m-3), and Cr (0.53 ng m-3), were observed in air masses originating from North America and the concentrations were within the same concentration range to those reported previously in the literature for remote marine aerosols. Fe (12.26 ng m-3), Ti (0.91 ng m-3), and Mn (0.35 ng m-3) showed higher concentrations when air mass came from Europe and the Canary Islands. Pb concentration was low (20) for Zn, Cu, Ni, Cr, Pb, and Se. The observed enrichment of the elements was attributed to crustal, marine, anthropogenic, and biogenic sources, as well as long-range transport and resuspension. Zn, Cu and Pb were indicators of anthropogenic activities, while Ti and Sr were indicators of crustal and marine origin, respectively. Oceanic and biogenic emissions might have contributed to most of the Se observed. This

  2. Aerosol size-resolved trace metal composition in remote northern tropical Atlantic marine environment: case study Cape Verde islands

    Directory of Open Access Journals (Sweden)

    K. W. Fomba

    2013-05-01

    Full Text Available Size-resolved trace metal concentrations of 15 elements in aerosol particles at the Cape Verde Atmospheric Observatory (CVAO under remote background conditions were investigated through analysis of aerosol samples collected during intensive field studies from January 2007 to November 2011 using total reflection x-ray fluorescence (TXRF. The identification of the main air mass origin that influence remote marine aerosol in the northern tropical Atlantic has been investigated. In total, 317 samples were collected. The dataset was analyzed according to the main air mass inflow at the station. We found that remote conditions make up about 45% of the meteorological conditions in a year at CVAO and thus the northern tropical Atlantic. Surprisingly, air masses from North America are often responsible for higher trace metal concentrations in this region. Elements such as Zn, Pb, Cu, Cr, Ni, and V were mostly found in the submicron size fractions, while elements with dominant crustal or oceanic origin such as Fe, Ti, Mn, Sr, and Rb were found in the coarse fractions (>1 μm. The highest metal concentrations, especially for Zn (3.23 ng m−3, Cu (0.81 ng m−3, Sr (2.63 ng m−3, and Cr (0.53 ng m−3, were observed in air masses originating from North America and the concentrations were within the same concentration range to those reported previously in the literature for remote marine aerosols. Fe (12.26 ng m−3, Ti (0.91 ng m−3, and Mn (0.35 ng m−3 showed higher concentrations when air mass came from Europe and the Canary Islands. Pb concentration was low (−3 and did not vary significantly with air mass direction. The low Pb concentration is indicative of the complete phase-out of leaded gasoline even in African countries. Crustal enrichment factor values decreased from fine to coarse-mode particles with low values (20 for Zn, Cu, Ni, Cr, Pb, and Se. The observed enrichment of the elements was attributed to crustal, marine, anthropogenic, and

  3. Dictyoceratida (Porifera: Demospongiae) from Tropical Southwestern Atlantic (Northeastern Brazil, Sergipe State) and the description of three new species.

    Science.gov (United States)

    Sandes, Joana; Pinheiro, Ulisses

    2014-07-21

    Five species of dictyoceratid sponges were collected from trawling on the continental shelf of Sergipe State, Northeastern Brazil, of which three are new to science: Ircinia sergipana sp. nov., Ircinia repens sp. nov., Ircinia strobilina, Hyattella cavernosa and Smenospongia ramosa sp. nov., the latter the first record of the genus Smenospongia from Brazil. 

  4. Application of remote sensing to the study of the pelagic spiny lobster larval transport in the Tropical Atlantic

    Directory of Open Access Journals (Sweden)

    Camila Aguirre Góes Rudorff

    2009-03-01

    Full Text Available The connectivity of marine populations via larval dispersal is crucial for the maintenance of fisheries production and biodiversity. Because larval dispersion takes place on different spatial scales, global operational satellite data can be successfully used to investigate the connectivity of marine populations on different spatial and temporal scales. In fact, satellite data have long been used for the study of the large and mesoscale biological processes associated with ocean dynamics. This paper presents simulations of spiny lobster larvae transport in the Tropical Atlantic using the geostrophic currents, generated by altimetry that feeds an advection/diffusion model. Simulations were conducted over the Tropical Atlantic (20ºN to 15ºS, considering four larvae release areas: the Cape Verde Archipelago, the Ivory Coast, Ascension Island and Fernando de Noronha Archipelago. We used mean geostrophic current (MGC calculated from 2001 to 2005 to represent the mean circulation of the Tropical Atlantic. We also ran the model for the El Niño geostrophic current regime (ENGC using part of the MGC data, representing the El Niño 2002/2003 event. Results suggest that the intensification of the mesoscale ocean processes associated with El Niño events promotes the connectivity between populations, increasing the chances of a genetic flux among different stocks. We concluded that the altimetry geostrophic current data together with a relatively simple advection/diffusion model can provide useful information about the physical dynamics necessary to conduct studies on larval dispersion.A conectividade de populações marinhas através da dispersão larval é crucial para a manutenção da produção pesqueira e da biodiversidade. A dispersão de larvas ocorre em diferentes escalas espaciais e temporais, de forma que o recobrimento global e escala sinóptica fazem dos dados de satélite ferramentas importantes para esses estudos. O objetivo deste artigo

  5. A new species of Trichopeltarion A. Milne-Edwards, 1880, from the Southwestern Atlantic (Crustacea: Brachyura: Atelecyclidae

    Directory of Open Access Journals (Sweden)

    Marcos Tavares

    2005-01-01

    Full Text Available A new species of Trichopeltarion A. Milne-Edwards, 1880, is described from off coast of Brazil, namely Trichopeltarion pezzutoi n. sp. The new species is compared to its Atlantic congeners, Trichopeltarion nobile A. Milne-Edwards, 1880, and Trichopeltarion intesi (Crosnier, 1981. The record of T. nobile from Brazil should actually be attributed to T. pezzutoi n. sp. The differences between the genera Trichopeltarion and Peltarion Jacquinot, 1847 are discussed.Uma nova espécie do gênero Trichopeltarion A. Milne-Edwards, 1880 coligida no talude continental brasileiro é descrita e ilustrada, nomeadamente Trichopeltarion pezzutoi n. sp. A nova espécie é comparada às suas congêneres do oceano Atlântico, Trichopeltarion nobile A. Milne-Edwards, 1880 e Trichopeltarion intesi (Crosnier, 1981. O registro de T. nobile para o Brasil deve ser atribuído à T. pezzutoi n. sp. São discutidas as diferenças entre os gêneros Trichopeltarion e Peltarion Jacquinot, 1847.

  6. Otolith chemical composition as a useful tool for sciaenid stock discrimination in the south-western Atlantic

    Directory of Open Access Journals (Sweden)

    Alejandra V. Volpedo

    2006-06-01

    Full Text Available Striped weakfish (Cynoscion guatucupa and whitemouth croaker (Micropogonias furnieri are important commercial and recreational species found in abundance along the South American Atlantic coast. In recent years otolith chemical composition has been used as a tool for identifying fish stocks for several species. The chemical composition of C. guatucupa and M. furnieri otoliths was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES in samples from coastal sites (Partido de La Costa, Mar del Plata and San Blás Bay. Significant differences in the ratios of Mg/Ca, Mn/Ca and Sr/Ca for C. guatucupa otoliths and Cd/Ca, Cu/Ca, Mg/Ca, Sr/Ca and Zn/Ca for M. furnieri otoliths suggest the existence of two different fish stocks, one originating in the north (including Samborombón Bay and Partido de La Costa fisheries and another originating in the south (including “El Rincón” and San Blás fisheries. These results agree with previous studies on the same species using different methodologies. These stocks may be separated by an oceanographic barrier, the “Frente El Rincón”. Otolith chemical composition has not been previously used in South America for identifying fish stocks and may be a simple, quick and useful tool for the sustainable exploitation and management of commercial species.

  7. North Atlantic Tropical Cyclones: historical simulations and future changes with the new high-resolution Arpege AGCM.

    Science.gov (United States)

    Pilon, R.; Chauvin, F.; Palany, P.; Belmadani, A.

    2017-12-01

    A new version of the variable high-resolution Meteo-France Arpege atmospheric general circulation model (AGCM) has been developed for tropical cyclones (TC) studies, with a focus on the North Atlantic basin, where the model horizontal resolution is 15 km. Ensemble historical AMIP (Atmospheric Model Intercomparison Project)-type simulations (1965-2014) and future projections (2020-2080) under the IPCC (Intergovernmental Panel on Climate Change) representative concentration pathway (RCP) 8.5 scenario have been produced. TC-like vortices tracking algorithm is used to investigate TC activity and variability. TC frequency, genesis, geographical distribution and intensity are examined. Historical simulations are compared to best-track and reanalysis datasets. Model TC frequency is generally realistic but tends to be too high during the rst decade of the historical simulations. Biases appear to originate from both the tracking algorithm and model climatology. Nevertheless, the model is able to simulate extremely well intense TCs corresponding to category 5 hurricanes in the North Atlantic, where grid resolution is highest. Interaction between developing TCs and vertical wind shear is shown to be contributing factor for TC variability. Future changes in TC activity and properties are also discussed.

  8. Porphyrocrinus daniellalevyae n. sp. (Echinodermata: Crinoidea), a sea lily from the tropical western Atlantic with a unique crown pattern.

    Science.gov (United States)

    Messing, Charles G

    2016-08-02

    Porphyrocrinus daniellalevyae, new species, is described from irregular, hard-substrate, deep island slope habitats in the tropical western Atlantic Ocean (northwestern Bahamas and, probably, Honduras). It represents the first record of the genus from the western Atlantic, and is the first crinoid, living or fossil, known to gradually increase its number of rays with increasing size and, ostensibly, growth. The four known specimens have 8, 12, 14 and 15 radial ossicles, which give rise to undivided arms. The method of augmentation is unknown, although the possibility of autotomy of one and regrowth of two in its place is discussed. Augmentation of radial number may also account for the absence of an aboral nerve ring associated with the radial ring, unlike the arrangement in almost all living crinoids in which the nervous system has been examined. Ligamentary articulations (trifascial synarthries) exhibit fulcral ridge-and groove architecture between arm ossicle pairs that remains to be described for other members of the genus. The species also exhibits a filamentous arm tip lacking pinnules that has only been described for one other species of Porphyrocrinus.

  9. Major Variations in Sub-Tropical North Atlantic Heat Transport at Short Timescales: Causes and Consequences

    Science.gov (United States)

    Moat, Ben; Josey, Simon; Sinha, Bablu; Blaker, Adam; Smeed, David; McCarthy, Gerard; Johns, William; Hirschi, Joel; Frajka-Williams, Eleanor; Rayner, Darren; Duchez, Aurelie; Coward, Andrew

    2017-04-01

    Variability in the North Atlantic ocean heat transport at 26.5°N on short (5-day) timescales is identified and contrasted with different behaviour at monthly intervals using a combination of RAPID/MOCHA/WBTS measurements and the NEMO-LIM2 1/12° ocean circulation/sea ice model. Wind forcing plays the leading role in establishing the heat transport variability through the Ekman transport response of the ocean and the associated driving atmospheric conditions vary significantly with timescale. We find that at 5-day timescales the largest changes in the heat transport across 26.5N coincide with north-westerly airflows originating over the American land mass that drive strong southward anomalies in the Ekman flow. During these events the northward heat transport reduces by 0.5-0.7 PW (i.e. about 50% of the mean). In contrast, the Ekman transport response at longer monthly timescales is smaller in magnitude (0.2-0.3 PW) and consistent with expected variations in the leading mode of North Atlantic atmospheric variability, the North Atlantic Oscillation. The north-westerly airflow mechanism can have a prolonged influence beyond the central 5-day timescale and on occasion can reduce the accumulated winter ocean heat transport into the north Atlantic by 40%.

  10. Transport of Antarctic bottom water through the Kane Gap, tropical NE Atlantic Ocean

    NARCIS (Netherlands)

    Morozov, E.G.; Tarakanov, R.Y.; van Haren, H.

    2013-01-01

    We study low-frequency properties of the Antarctic Bottom Water (AABW) flow through the Kane Gap (9° N) in the Atlantic Ocean. The measurements in the Kane Gap include five visits with CTD (Conductivity-Temperature-Depth) sections in 2009–2012 and a year-long record of currents on a mooring using

  11. Tropical South-East Atlantic response to ENSO as an ecosystem ...

    African Journals Online (AJOL)

    Cases were selected based on indices of Pacific sea surface temperature and South-East African rainfall. ... an El Niño event, and higher sardine Sardinops sagax catches tend to follow a La Niña event, through the northward and southward shift respectively of the South Atlantic anticyclone and attendant coastal upwelling.

  12. Field and geochemical constraints on the relationship between the Apoteri basalts (northern Brazil, southwestern Guyana) and the Central Atlantic Magmatic Province

    Science.gov (United States)

    Pinto, Viter M.; Santos, João Orestes S.; Ronchi, Luiz H.; Hartmann, Léo A.; Bicudo, Carlos Alberto; de Souza, Vladimir

    2017-11-01

    In northern Brazil, Roraima state and southwestern Guyana, basalt flows characterized by inflated pahoehoe structure occur along the margins of the Tacutu Rift Valley, dykes intrude the Paleoproterozoic basement close to the boundary of the rift system with concordant, NE-trend. The dykes and flows belong to Apoteri magmatism. New field, geochemical data (major, trace and rare-earth elements) and chemical stratigraphy of the Apoteri magmatism indicate petrographic and chemical homogeneity characteristic of continental tholeiitic basalts. The basalt flows of Morro Redondo and Nova Olinda sites show two distinct chemical groups: a) the lower flows with intermediate TiO2 content (ITi group) ranging from 1.09 to 1.41 wt%, MgO (5.64-6.46 wt%) and Ni (43-53 ppm) contents; and b) the upper flows with lower TiO2 content (LTi group) = 0.75 to 0.78 wt%, higher MgO = 7.95-8.85 wt% and Ni = 105-115 ppm. The two magma types share many characteristics in high field strength elements (HFSE) and rare earth elements (REE), but in detail significant differences exist in REE ratios, e.g. (La/Yb)N of ∼4.0 for ITi and 3.2 for LTi and this may be explained by fractional crystallization. The chemical compositions of the Apoteri dykes are similar the ITi group analyses, suggesting that they have the same origin. The La/Ba versus La/Nb diagram is indicative of large ion lithophile elements (LILE) enrichment and LILE/HFSE fractionation in the mantle source, and the data favor a dominant subcontinental lithospheric mantle (SCLM) component in the origin of the Apoteri flows and dykes. These data show consistent similar chemical characteristics and correspond to other tholeiitic flows from the large Central Atlantic Magmatic Province (CAMP), especially eastern USA.

  13. Contrasting cost-benefit strategy between lianas and trees in a tropical seasonal rain forest in southwestern China.

    Science.gov (United States)

    Zhu, Shi-Dan; Cao, Kun-Fang

    2010-07-01

    Lianas are an important component of tropical forests and often abundant in open habitats, such as tree-fall gaps, forest edges, and disturbed forests. The abundance of lianas in tropical forests has been increasing as a result of global environmental change and increasing forest fragmentation. In order to understand this phenomenon in terms of leaf functional traits and to evaluate their competitive potential, we conducted a cost-benefit analysis of leaves from 18 liana species and 19 tree species in a tropical seasonal rain forest. The results revealed that lianas were scattered in a group distinct from trees along the first axis of a principal component analysis using 15 leaf ecophysiological traits, being located at the quick-return end of the leaf economics spectrum, with higher specific leaf area and photosynthetic rates (A), higher photosynthetic nitrogen (N) and phosphorus (P) use efficiencies, a lower leaf construction cost per unit leaf area (CC) and cost-benefit ratio (CC/A), and a shorter leaf life span (LLS). Trees showed the opposite trends. The results indicate that lianas can grow faster and capture resources more efficiently than trees in disturbed, open habitats. The positive relationship between LLS and CC/A revealed a trade-off between leaf construction cost and benefit over time. The 37 species analyzed had a mean foliar N/P ratio of 20, indicating that the forest was characterized by a P deficit. With an increasing atmospheric CO(2) concentration, the higher nutrient use efficiency could benefit lianas more than trees in terms of productivity, possibly also contributing to the increasing abundance of lianas in nutrient-limited tropical forests.

  14. Oxygen Isotope Speleothem record of Decadal and Multidecadal Atlantic Oscillations over the last millennium in Southwestern Morocco

    Science.gov (United States)

    Ait Brahim, Yassine; Sha, LiJuan; Sifeddine, Abdelfettah; Cheng, Hai; Bouchaou, Lhoussaine; Da Cruz Junior, Francisco William; Khodri, Myriam; Peerbocus, Nawaaz; Mariller, Alexandre; Apaestegui, James; Guyot, Jean-Loup; Auler, Augusto; Hassane Beraaouz, El

    2016-04-01

    In this work, we present a stable oxygen isotope (δ18O) speleothem record from Ifoulki cave located South-West of Morocco (N 30°42'29'', W 09°19'39'' and 1267 meters above sea level). The age model, based on eighteen U-Th dates, reveals that the record covers the AD 790-1953 period with a data resolution of ~1.7 years. Stable oxygen isotope variations show substantial decadal to multi-decadal swings between dry and humid periods. The Medieval Climate Anomaly (MCA) is characterized by the longest period with δ18O values above the average, suggestive of pronounced drying possibly as a response to positive North Atlantic Oscillation (NAO) phases and increased volcanic activity during this period. However, at least two short wet phases are recognized during the MCA in Morocco, with peaks centered on the years AD 1040 and AD 1190 and seem to overlap with negative NAO phases as recorded in a recently published NAO reconstruction for the last millennium. During the next centuries, the NAO again depicts predominantly negative values and the δ18O drops below the average during the Little Ice Age (LIA). Furthermore, a striking resemblance is observed between our record and another recently published stalagmite record from the Piste cave in Northeastern Morocco, which is quite remarkable given the different type of tracers (δ18O vs. Mg and Sr) obtained from different environments (Western High Atlas vs. Northeastern Middle Atlas and ~634 km away). Comparison with regional paleorecords from other studies also reveals the replication of many characteristic climate features from the last millennium, first detected in Northern Morocco and the Iberian Peninsula. In particular, the evidence of generally dry conditions during the MCA and wetter conditions in the LIA, which is confirmed by all the paleorecords. These similarities indicate coherent climate variability in Northwest Africa and the Iberian Peninsula and suggest a strong regional control of the NAO during the last

  15. Abundance and distribution of archaeal acetyl-CoA/propionyl-CoA carboxylase genes indicative for putatively chemoautotrophic Archaea in the tropical Atlantic's interior

    OpenAIRE

    Bergauer, Kristin; Sintes, Eva; van Bleijswijk, Judith; Witte, Harry; Herndl, Gerhard J; Lueders, Tillmann

    2013-01-01

    Recently, evidence suggests that dark CO2 fixation in the pelagic realm of the ocean does not only occur in the suboxic and anoxic water bodies but also in the oxygenated meso- and bathypelagic waters of the North Atlantic. To elucidate the significance and phylogeny of the key organisms mediating dark CO2 fixation in the tropical Atlantic, we quantified functional genes indicative for CO2 fixation. We used a Q-PCR-based assay targeting the bifunctional acetyl-CoA/propionyl-CoA carboxylase (a...

  16. The tropical Atlantic surface wind divergence belt and its effect on clouds

    OpenAIRE

    Y. Tubul; I. Koren; O. Altaratz

    2015-01-01

    A well-defined surface wind divergence (SWD) belt with distinct cloud properties forms over the equatorial Atlantic during the boreal summer months. This belt separates the deep convective clouds of the intertropical convergence zone (ITCZ) from the shallow marine stratocumulus cloud decks forming over the cold-water subtropical region of the southern Hadley cell. Using the QuikSCAT-SeaWinds and Aqua-MODIS instruments, we examined the large-scale spatiotemporal ...

  17. Deglacial Tropical Atlantic subsurface warming links ocean circulation variability to the West African Monsoon.

    Science.gov (United States)

    Schmidt, Matthew W; Chang, Ping; Parker, Andrew O; Ji, Link; He, Feng

    2017-11-13

    Multiple lines of evidence show that cold stadials in the North Atlantic were accompanied by both reductions in Atlantic Meridional Overturning Circulation (AMOC) and collapses of the West African Monsoon (WAM). Although records of terrestrial change identify abrupt WAM variability across the deglaciation, few studies show how ocean temperatures evolved across the deglaciation. To identify the mechanism linking AMOC to the WAM, we generated a new record of subsurface temperature variability over the last 21 kyr based on Mg/Ca ratios in a sub-thermocline dwelling planktonic foraminifera in an Eastern Equatorial Atlantic (EEA) sediment core from the Niger Delta. Our subsurface temperature record shows abrupt subsurface warming during both the Younger Dryas (YD) and Heinrich Event 1. We also conducted a new transient coupled ocean-atmosphere model simulation across the YD that better resolves the western boundary current dynamics and find a strong negative correlation between AMOC strength and EEA subsurface temperatures caused by changes in ocean circulation and rainfall responses that are consistent with the observed WAM change. Our combined proxy and modeling results provide the first evidence that an oceanic teleconnection between AMOC strength and subsurface temperature in the EEA impacted the intensity of the WAM on millennial time scales.

  18. Variability in north tropical atlantic over the last 20 000 years and holocene gulf stream activity

    International Nuclear Information System (INIS)

    Cleroux, C.

    2007-10-01

    Modern oceanographical studies shown that most of the ocean heat content in the North Atlantic Western Boundary Current region is stored in the upper 400 meters. To study past heat content and Gulf Stream activity, we performed coupled analyses of oxygen isotopic and trace elemental composition on several foraminifera species to reconstruct upper water column temperature and salinity. Calcification depths of Globorotalia inflata, Globorotalia truncatulinoides and Pulleniatina obliquiloculata have been constrain by correlating modern hydrographic data to oxygen isotopic measurement of North Atlantic core-top samples. We found that the three deep-dwelling foraminifera species have a preferred habitat at the base of the seasonal thermocline (Cleroux et al, 2007). The same set of North Atlantic core-tops has been used to define relationships between trace elemental compositions and temperature. We established calibrations between Mg/Ca ratio or Sr/Ca ratio and temperature for the three deep-dwelling foraminifera (Cleroux et al, submitted). We apply this strategy on the core MD99-2203 located off Cape Hatteras where the Gulf Stream separate from the United States coast. High-resolution surface reconstructions over the Holocene show low amplitude periodic temperature and salinity changes that could be related to NAO type mechanisms. Large hydrological changes in sub-surface reflect variations of Labrador current and Mode Water influences. Using recent studies on Mode Water formation and Gulf Stream heat advection, we interpret our results in term of ocean heat content and Gulf Stream activity. (author)

  19. Attenuation of biologically effective UV radiation in tropical Atlantic waters measured with a biochemical DNA dosimeter

    NARCIS (Netherlands)

    Boelen, P.; Obernosterer, I; Vink, A.A; Buma, A.G.J.

    A biochemical dosimeter was developed to study the attenuation of biologically effective UV radiation in marine tropical waters. Small quartz vials were used containing a solution of DNA molecules; the vials were incubated at discrete water depths. Subsequently, DNA damage was determined in these

  20. Attenuation of biologically effective UV radiation in tropical atlantic waters measured with a biochemical DNA dosimeter

    NARCIS (Netherlands)

    Boelen, P.; Obernosterer, I.; Vink, A.A.; Buma, A.G.J.

    1999-01-01

    A biochemical dosimeter was developed to study the attenuation of biologically effective UV radiation in marine tropical waters. Small quartz vials were used containing a solution of DNA molecules; the vials were incubated at discrete water depths. Subsequently, DNA damage was determined in these

  1. UVBR-induced DNA damage in natural marine picoplankton assemblages in the tropical Atlantic Ocean

    NARCIS (Netherlands)

    Boelen, P; de Boer, MK; Kraay, GW; Veldhuis, MJW; Buma, AGJ

    2000-01-01

    UVBR (ultraviolet-B radiation: 280 to 315 nm)-induced DNA damage, measured as cyclobutane pyrimidine dimers (CPDs), was determined in size fractions of natural populations of bacterio- and phytoplankton collected in marine tropical waters. Mean biologically effective UVBR doses in the wind-mixed

  2. Evaluating Atlantic tropical cyclone track error distributions for use in probabilistic forecasts of wind distribution

    OpenAIRE

    Neese, Jay M.

    2010-01-01

    Approved for public release; distribution is unlimited This thesis investigates whether the National Hurricane Center (NHC) operational product for producing probabilistic forecasts of tropical cyclone (TC) wind distributions could be further improved by examining the distributions of track errors it draws upon to calculate probabilities. The track spread/skill relationship for several global ensemble prediction system forecasts is examined as a condition for a description of a full p...

  3. Seasonality of freshwater bacterioplankton diversity in two tropical shallow lakes from the Brazilian Atlantic Forest.

    Science.gov (United States)

    Ávila, Marcelo P; Staehr, Peter A; Barbosa, Francisco A R; Chartone-Souza, Edmar; Nascimento, Andréa M A

    2017-01-01

    Bacteria are highly important for the cycling of organic and inorganic matter in freshwater environments; however, little is known about the diversity of bacterioplankton in tropical systems. Studies on carbon and nutrient cycling in tropical lakes suggest a very different seasonality from that of temperate climates. Here, we used 16S rRNA gene next-generation sequencing (NGS) to investigate seasonal changes in bacterioplankton communities of two tropical lakes, which differed in trophic status and mixing regime. Our findings revealed seasonally and depth-wise highly dynamic bacterioplankton communities. Differences in richness and structure appeared strongly related to the physicochemical characteristics of the water column, especially phosphate, pH and oxygen. Bacterioplankton communities were dominated by common taxonomic groups, such as Synechococcus and Actinobacteria acI, as well as rare and poorly characterized taxa such as 'Candidatus Methylacidiphilum' (Verrucomicrobia). Stratification and oxygen depletion during the rainy season promoted the occurrence of anoxygenic phototrophic and methanotrophic bacteria important for carbon and nutrient cycling. Differences in lake mixing regime were associated with seasonal beta diversity. Our study is the first attempt to use NGS for cataloging the diversity of bacterioplankton communities in Brazilian lakes and thus contributes to the ongoing worldwide endeavor to characterize freshwater lake bacterioplankton signatures. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Remote tropical and sub-tropical responses to Amazon deforestation

    Science.gov (United States)

    Badger, Andrew M.; Dirmeyer, Paul A.

    2016-05-01

    Replacing natural vegetation with realistic tropical crops over the Amazon region in a global Earth system model impacts vertical transport of heat and moisture, modifying the interaction between the atmospheric boundary layer and the free atmosphere. Vertical velocity is decreased over a majority of the Amazon region, shifting the ascending branch and modifying the seasonality of the Hadley circulation over the Atlantic and eastern Pacific oceans. Using a simple model that relates circulation changes to heating anomalies and generalizing the upper-atmosphere temperature response to deforestation, agreement is found between the response in the fully-coupled model and the simple solution. These changes to the large-scale dynamics significantly impact precipitation in several remote regions, namely sub-Saharan Africa, Mexico, the southwestern United States and extratropical South America, suggesting non-local climate repercussions for large-scale land use changes in the tropics are possible.

  5. Rhodolith beds are major CaCO3 bio-factories in the tropical South West Atlantic.

    Directory of Open Access Journals (Sweden)

    Gilberto M Amado-Filho

    Full Text Available Rhodoliths are nodules of non-geniculate coralline algae that occur in shallow waters (<150 m depth subjected to episodic disturbance. Rhodolith beds stand with kelp beds, seagrass meadows, and coralline algal reefs as one of the world's four largest macrophyte-dominated benthic communities. Geographic distribution of rhodolith beds is discontinuous, with large concentrations off Japan, Australia and the Gulf of California, as well as in the Mediterranean, North Atlantic, eastern Caribbean and Brazil. Although there are major gaps in terms of seabed habitat mapping, the largest rhodolith beds are purported to occur off Brazil, where these communities are recorded across a wide latitudinal range (2°N-27°S. To quantify their extent, we carried out an inter-reefal seabed habitat survey on the Abrolhos Shelf (16°50'-19°45'S off eastern Brazil, and confirmed the most expansive and contiguous rhodolith bed in the world, covering about 20,900 km(2. Distribution, extent, composition and structure of this bed were assessed with side scan sonar, remotely operated vehicles, and SCUBA. The mean rate of CaCO(3 production was estimated from in situ growth assays at 1.07 kg m(-2 yr(-1, with a total production rate of 0.025 Gt yr(-1, comparable to those of the world's largest biogenic CaCO(3 deposits. These gigantic rhodolith beds, of areal extent equivalent to the Great Barrier Reef, Australia, are a critical, yet poorly understood component of the tropical South Atlantic Ocean. Based on the relatively high vulnerability of coralline algae to ocean acidification, these beds are likely to experience a profound restructuring in the coming decades.

  6. Separating the Effects of Tropical Atlantic and Pacific SST-driven Climate Variability on Amazon Carbon Exchange

    Science.gov (United States)

    Liptak, J.; Keppel-Aleks, G.

    2016-12-01

    Amazon forests store an estimated 25% percent of global terrestrial carbon per year1, 2, but the responses of Amazon carbon uptake to climate change is highly uncertain. One source of this uncertainty is tropical sea surface temperature variability driven by teleconnections. El Nino-Southern Oscillation (ENSO) is a key driver of year-to-year Amazon carbon exchange, with associated temperature and precipitation changes favoring net carbon storage in La Nina years, and net carbon release during El Nino years3. To determine how Amazon climate and terrestrial carbon fluxes react to ENSO alone and in concert with other SST-driven teleconnections such as the Atlantic Multidecadal Oscillation (AMO), we force the atmosphere (CAM5) and land (CLM4) components of the CESM(BGC) with prescribed monthly SSTs over the period 1950—2014 in a Historical control simulation. We then run an experiment (PAC) with time-varying SSTs applied only to the tropical equatorial Pacific Ocean, and repeating SST seasonal cycle climatologies elsewhere. Limiting SST variability to the equatorial Pacific indicates that other processes enhance ENSO-driven Amazon climate anomalies. Compared to the Historical control simulation, warming, drying and terrestrial carbon loss over the Amazon during El Nino periods are lower in the PAC simulation, especially prior to 1990 during the cool phase of the AMO. Cooling, moistening, and net carbon uptake during La Nina periods are also reduced in the PAC simulation, but differences are greater after 1990 during the warm phase of the AMO. By quantifying the relationships among climate drivers and carbon fluxes in the Historical and PAC simulations, we both assess the sensitivity of these relationships to the magnitude of ENSO forcing and quantify how other teleconnections affect ENSO-driven Amazon climate feedbacks. We expect that these results will help us improve hypotheses for how Atlantic and Pacific climate trends will affect future Amazon carbon carbon

  7. Contrasted accumulation patterns of persistent organic pollutants and mercury in sympatric tropical dolphins from the south-western Indian Ocean

    International Nuclear Information System (INIS)

    Dirtu, Alin C.; Malarvannan, Govindan; Das, Krishna; Dulau-Drouot, Violaine; Kiszka, Jeremy J.; Lepoint, Gilles; Mongin, Philippe; Covaci, Adrian

    2016-01-01

    Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ 13 C and δ 15 N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ 15 N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation. - Highlights: • POPs and total Hg were

  8. Feeding strategies of tropical and subtropical calanoid copepods throughout the eastern Atlantic Ocean - Latitudinal and bathymetric aspects

    Science.gov (United States)

    Bode, Maya; Hagen, Wilhelm; Schukat, Anna; Teuber, Lena; Fonseca-Batista, Debany; Dehairs, Frank; Auel, Holger

    2015-11-01

    The majority of global ocean production and total export production is attributed to oligotrophic oceanic regions due to their vast regional expanse. However, energy transfers, food-web structures and trophic relationships in these areas remain largely unknown. Regional and vertical inter- and intra-specific differences in trophic interactions and dietary preferences of calanoid copepods were investigated in four different regions in the open eastern Atlantic Ocean (38°N to 21°S) in October/November 2012 using a combination of fatty acid (FA) and stable isotope (SI) analyses. Mean carnivory indices (CI) based on FA trophic markers generally agreed with trophic positions (TP) derived from δ15N analysis. Most copepods were classified as omnivorous (CI ∼0.5, TP 1.8 to ∼2.5) or carnivorous (CI ⩾ 0.7, TP ⩾ 2.9). Herbivorous copepods showed typical CIs of ⩽0.3. Geographical differences in δ15N values of epi- (200-0 m) to mesopelagic (1000-200 m) copepods reflected corresponding spatial differences in baseline δ15N of particulate organic matter from the upper 100 m. In contrast, species restricted to lower meso- and bathypelagic (2000-1000 m) layers did not show this regional trend. FA compositions were species-specific without distinct intra-specific vertical or spatial variations. Differences were only observed in the southernmost region influenced by the highly productive Benguela Current. Apparently, food availability and dietary composition were widely homogeneous throughout the mesotrophic oceanic regions of the tropical and subtropical Atlantic. Four major species clusters were identified by principal component analysis based on FA compositions. Vertically migrating species clustered with epi- to mesopelagic, non-migrating species, of which only Neocalanus gracilis was moderately enriched in lipids with 16% of dry mass (DM) and stored wax esters (WE) with 37% of total lipid (TL). All other species of this cluster had low lipid contents (<10% DM

  9. Variation in the diel vertical distributions of larvae and transforming stages of oceanic fishes across the tropical and equatorial Atlantic

    Science.gov (United States)

    Olivar, M. Pilar; Contreras, Tabit; Hulley, P. Alexander; Emelianov, Mikhail; López-Pérez, Cristina; Tuset, Víctor; Castellón, Arturo

    2018-01-01

    The vertical distributions of early developmental stages of oceanic fishes were investigated across the tropical and equatorial Atlantic, from oligotrophic waters close to the Brazilian coast to more productive waters close to the Mauritanian Upwelling Region. Stratification of the water column was observed throughout the study region. Fishes were caught with a MOCNESS-1 net with mouth area of 1 m2 at 11 stations. Each station was sampled both during the day and at night within a single 24-h period. The investigation covered both larvae and transforming stages from the surface to 800 m depth. Distribution patterns were analysed, and weighted mean depths for the larvae and transforming stages of each species were calculated for day and night conditions. Forty-seven different species were found. The highest number of species occurred in the three stations south of Cape Verde Islands, characterized by a mixture of South Atlantic Central Water (SACW) and Eastern North Atlantic Central Water (ENACW). There was a marked drop in species richness in the three stations closer to the African upwelling, dominated by ENACW. The highest abundances occurred in the families Myctophidae, Sternoptychidae, Gonostomatidae and Phosichthyidae. Day and night vertical distributions of larvae and transforming stages showed contrasting patterns, both in the depths of the main concentration layers in the water column, and in the diel migration patterns (where these were observed). Larvae generally showed a preference for the upper mixed layer (ca. 0-50 m) and upper thermocline (ca. 50-100 m), except for sternoptychids, which were also abundant in the lower thermocline layer (100-200 m) and even extended into the mesopelagic zone (down to 500 m). Transforming stages showed a more widespread distribution, with main concentrations in the mesopelagic zone (200-800 m). Larvae showed peak concentrations in the more illuminated and zooplankton-rich upper mixed layers during the day and a wider

  10. Atlantic tropical cyclones water budget in observations and CNRM-CM5 model

    Science.gov (United States)

    Chauvin, Fabrice; Douville, Hervé; Ribes, Aurélien

    2017-12-01

    Water budgets in tropical cyclones (TCs) are computed in the ERA-interim (ERAI) re-analysis and the CNRM-CM5 model for the late 20th and 21st centuries. At a 6-hourly timescale and averaged over a 5° × 5° box around a TC center, the main contribution to rainfall is moisture convergence, with decreasing contribution of evaporation for increasing rainfall intensities. It is found that TC rainfall in ERAI and the model are underestimated when compared with the tropical rainfall measuring mission (TRMM), probably due to underestimated TC winds in ERAI vs. observed TCs. It is also found that relative increase in TC rainfall between the second half of the 20th and 21st centuries may surpass the rate of change suggested by the Clausius-Clapeyron formula. It may even reach twice this rate for reduced spatial domains corresponding to the highest cyclonic rainfall. This is in agreement with an expected positive feedback between TC rainfall intensity and dynamics.

  11. Targeted observations to improve tropical cyclone track forecasts in the Atlantic and eastern Pacific basins

    Science.gov (United States)

    Aberson, Sim David

    In 1997, the National Hurricane Center and the Hurricane Research Division began conducting operational synoptic surveillance missions with the Gulfstream IV-SP jet aircraft to improve operational forecast models. During the first two years, twenty-four missions were conducted around tropical cyclones threatening the continental United States, Puerto Rico, and the Virgin Islands. Global Positioning System dropwindsondes were released from the aircraft at 150--200 km intervals along the flight track in the tropical cyclone environment to obtain wind, temperature, and humidity profiles from flight level (around 150 hPa) to the surface. The observations were processed and formatted aboard the aircraft and transmitted to the National Centers for Environmental Prediction (NCEP). There, they were ingested into the Global Data Assimilation System that subsequently provides initial and time-dependent boundary conditions for numerical models that forecast tropical cyclone track and intensity. Three dynamical models were employed in testing the targeting and sampling strategies. With the assimilation into the numerical guidance of all the observations gathered during the surveillance missions, only the 12-h Geophysical Fluid Dynamics Laboratory Hurricane Model forecast showed statistically significant improvement. Neither the forecasts from the Aviation run of the Global Spectral Model nor the shallow-water VICBAR model were improved with the assimilation of the dropwindsonde data. This mediocre result is found to be due mainly to the difficulty in operationally quantifying the storm-motion vector used to create accurate synthetic data to represent the tropical cyclone vortex in the models. A secondary limit on forecast improvements from the surveillance missions is the limited amount of data provided by the one surveillance aircraft in regular missions. The inability of some surveillance missions to surround the tropical cyclone with dropwindsonde observations is a possible

  12. Comparison of automatic traps to capture mosquitoes (Diptera: Culicidae in rural areas in the tropical Atlantic rainforest

    Directory of Open Access Journals (Sweden)

    Ivy Luizi Rodrigues de Sa

    2013-12-01

    Full Text Available In several countries, surveillance of insect vectors is accomplished with automatic traps. This study addressed the performance of Mosquito Magnet® Independence (MMI in comparison with those of CDC with CO2 and lactic acid (CDC-A and CDC light trap (CDC-LT. The collection sites were in a rural region located in a fragment of secondary tropical Atlantic rainforest, southeastern Brazil. Limatus durhami and Limatus flavisetosus were the dominant species in the MMI, whereas Ochlerotatus scapularis was most abundant in CDC-A. Culex ribeirensis and Culex sacchettae were dominant species in the CDC-LT. Comparisons among traps were based on diversity indices. Results from the diversity analyses showed that the MMI captured a higher abundance of mosquitoes and that the species richness estimated with it was higher than with CDC-LT. Contrasting, difference between MMI and CDC-A was not statistically significant. Consequently, the latter trap seems to be both an alternative for the MMI and complementary to it for ecological studies and entomological surveillance.

  13. The genetic effects of Late Quaternary climatic changes over a tropical latitudinal gradient: diversification of an Atlantic Forest passerine.

    Science.gov (United States)

    d'Horta, Fernando M; Cabanne, Gustavo S; Meyer, Diogo; Miyaki, Cristina Y

    2011-05-01

    The increase in biodiversity from high to low latitudes is a widely recognized biogeographical pattern. According to the latitudinal gradient hypothesis (LGH), this pattern was shaped by differential effects of Late Quaternary climatic changes across a latitudinal gradient. Here, we evaluate the effects of climatic changes across a tropical latitudinal gradient and its implications to diversification of an Atlantic Forest (AF) endemic passerine. We studied the intraspecific diversification and historical demography of Sclerurus scansor, based on mitochondrial (ND2, ND3 and cytb) and nuclear (FIB7) gene sequences. Phylogenetic analyses recovered three well-supported clades associated with distinct latitudinal zones. Coalescent-based methods were applied to estimate divergence times and changes in effective population sizes. Estimates of divergence times indicate that intraspecific diversification took place during Middle-Late Pleistocene. Distinct demographic scenarios were identified, with the southern lineage exhibiting a clear signature of demographic expansion, while the central one remained more stable. The northern lineage, contrasting with LGH predictions, exhibited a clear sign of a recent bottleneck. Our results suggest that different AF regions reacted distinctly, even in opposite ways, under the same climatic period, producing simultaneously favourable scenarios for isolation and contact among populations. © 2011 Blackwell Publishing Ltd.

  14. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans

    Science.gov (United States)

    Estrada, Marta; Delgado, Maximino; Blasco, Dolors; Latasa, Mikel; Cabello, Ana María; Benítez-Barrios, Verónica; Fraile-Nuez, Eugenio; Mozetič, Patricija; Vidal, Montserrat

    2016-01-01

    We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011), which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists) community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform) of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1) A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET), and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore) and several diatoms, 2) a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component), 3) differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component) and 4) the occurrence of a diatom-dominated assemblage (the fourth principal

  15. Phytoplankton across Tropical and Subtropical Regions of the Atlantic, Indian and Pacific Oceans.

    Directory of Open Access Journals (Sweden)

    Marta Estrada

    Full Text Available We examine the large-scale distribution patterns of the nano- and microphytoplankton collected from 145 oceanic stations, at 3 m depth, the 20% light level and the depth of the subsurface chlorophyll maximum, during the Malaspina-2010 Expedition (December 2010-July 2011, which covered 15 biogeographical provinces across the Atlantic, Indian and Pacific oceans, between 35°N and 40°S. In general, the water column was stratified, the surface layers were nutrient-poor and the nano- and microplankton (hereafter phytoplankton, for simplicity, although it included also heterotrophic protists community was dominated by dinoflagellates, other flagellates and coccolithophores, while the contribution of diatoms was only important in zones with shallow nutriclines such as the equatorial upwelling regions. We applied a principal component analysis to the correlation matrix among the abundances (after logarithmic transform of the 76 most frequent taxa to synthesize the information contained in the phytoplankton data set. The main trends of variability identified consisted of: 1 A contrast between the community composition of the upper and the lower parts of the euphotic zone, expressed respectively by positive or negative scores of the first principal component, which was positively correlated with taxa such as the dinoflagellates Oxytoxum minutum and Scrippsiella spp., and the coccolithophores Discosphaera tubifera and Syracosphaera pulchra (HOL and HET, and negatively correlated with taxa like Ophiaster hydroideus (coccolithophore and several diatoms, 2 a general abundance gradient between phytoplankton-rich regions with high abundances of dinoflagellate, coccolithophore and ciliate taxa, and phytoplankton-poor regions (second principal component, 3 differences in dominant phytoplankton and ciliate taxa among the Atlantic, the Indian and the Pacific oceans (third principal component and 4 the occurrence of a diatom-dominated assemblage (the fourth

  16. Diet and stable isotope analyses reveal the feeding ecology of the orangeback squid Sthenoteuthis pteropus (Steenstrup 1855) (Mollusca, Ommastrephidae) in the eastern tropical Atlantic

    Science.gov (United States)

    Christiansen, Bernd; Javidpour, Jamileh; Piatkowski, Uwe; Puebla, Oscar; Gasca, Rebeca; Hoving, Henk-Jan T.

    2017-01-01

    In the eastern tropical Atlantic, the orangeback flying squid Sthenoteuthis pteropus (Steenstrup 1855) (Cephalopoda, Ommastrephidae) is a dominant species of the epipelagic nekton community. This carnivore squid has a short lifespan and is one of the fastest-growing squids. In this study, we characterise the role of S. pteropus in the pelagic food web of the eastern tropical Atlantic by investigating its diet and the dynamics of its feeding habits throughout its ontogeny and migration. During three expeditions in the eastern tropical Atlantic in 2015, 129 specimens were caught by hand jigging. Stomach content analyses (via visual identification and DNA barcoding) were combined with stable isotope data (∂15N and ∂13C) of muscle tissue to describe diet, feeding habits and trophic ecology of S. pteropus. Additionally, stable isotope analyses of incremental samples along the squid’s gladius—the chitinous spiniform structure supporting the muscles and organs—were carried out to explore possible diet shifts through ontogeny and migration. Our results show that S. pteropus preys mainly on myctophid fishes (e.g. Myctophum asperum, Myctophum nitidulum, Vinciguerria spp.), but also on other teleost species, cephalopods (e.g. Enoploteuthidae, Bolitinidae, Ommastrephidae), crustaceans and possibly on gelatinous zooplankton as well. The squid shows a highly opportunistic feeding behaviour that includes cannibalism. Our study indicates that the trophic position of S. pteropus may increase by approximately one trophic level from a mantle length of 15 cm to 47 cm. The reconstructed isotope-based feeding chronologies of the gladii revealed high intra- and inter-individual variability in the squid’s trophic position and foraging area. These findings are not revealed by diet or muscle tissue stable isotope analysis. This suggests a variable and complex life history involving individual variation and migration. The role of S. pteropus in transferring energy and nutrients

  17. Adequacy assessment of mathematical models in the dynamics of litter decomposition in a tropical forest Mosaic Atlantic, in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    FP. Nunes

    Full Text Available The study of litter decomposition and nutrient cycling is essential to know native forests structure and functioning. Mathematical models can help to understand the local and temporal litter fall variations and their environmental variables relationships. The objective of this study was test the adequacy of mathematical models for leaf litter decomposition in the Atlantic Forest in southeastern Brazil. We study four native forest sites in Parque Estadual do Rio Doce, a Biosphere Reserve of the Atlantic, which were installed 200 bags of litter decomposing with 20×20 cm nylon screen of 2 mm, with 10 grams of litter. Monthly from 09/2007 to 04/2009, 10 litterbags were removed for determination of the mass loss. We compared 3 nonlinear models: 1 – Olson Exponential Model (1963, which considers the constant K, 2 – Model proposed by Fountain and Schowalter (2004, 3 – Model proposed by Coelho and Borges (2005, which considers the variable K through QMR, SQR, SQTC, DMA and Test F. The Fountain and Schowalter (2004 model was inappropriate for this study by overestimating decomposition rate. The decay curve analysis showed that the model with the variable K was more appropriate, although the values of QMR and DMA revealed no significant difference (p> 0.05 between the models. The analysis showed a better adjustment of DMA using K variable, reinforced by the values of the adjustment coefficient (R2. However, convergence problems were observed in this model for estimate study areas outliers, which did not occur with K constant model. This problem can be related to the non-linear fit of mass/time values to K variable generated. The model with K constant shown to be adequate to describe curve decomposition for separately areas and best adjustability without convergence problems. The results demonstrated the adequacy of Olson model to estimate tropical forest litter decomposition. Although use of reduced number of parameters equaling the steps of the

  18. Twentieth century warming of the tropical Atlantic captured by Sr-U paleothermometry

    Science.gov (United States)

    Alpert, Alice E.; Cohen, Anne L.; Oppo, Delia W.; DeCarlo, Thomas M.; Gaetani, Glenn A.; Hernandez-Delgado, Edwin A.; Winter, Amos; Gonneea, Meagan

    2017-01-01

    Coral skeletons are valuable archives of past ocean conditions. However, interpretation of coral paleotemperature records is confounded by uncertainties associated with single-element ratio thermometers, including Sr/Ca. A new approach, Sr-U, uses U/Ca to constrain the influence of Rayleigh fractionation on Sr/Ca. Here we build on the initial Pacific Porites Sr-U calibration to include multiple Atlantic and Pacific coral genera from multiple coral reef locations spanning a temperature range of 23.15–30.12°C. Accounting for the wintertime growth cessation of one Bermuda coral, we show that Sr-U is strongly correlated with the average water temperature at each location (r2 = 0.91, P < 0.001, n = 19). We applied the multispecies spatial calibration between Sr-U and temperature to reconstruct a 96 year long temperature record at Mona Island, Puerto Rico, using a coral not included in the calibration. Average Sr-U derived temperature for the period 1900–1996 is within 0.12°C of the average instrumental temperature at this site and captures the twentieth century warming trend of 0.06°C per decade. Sr-U also captures the timing of multiyear variability but with higher amplitude than implied by the instrumental data. Mean Sr-U temperatures and patterns of multiyear variability were replicated in a second coral in the same grid box. Conversely, Sr/Ca records from the same two corals were inconsistent with each other and failed to capture absolute sea temperatures, timing of multiyear variability, or the twentieth century warming trend. Our results suggest that coral Sr-U paleothermometry is a promising new tool for reconstruction of past ocean temperatures.

  19. Responses of tropical legumes from the Brazilian Atlantic Rainforest to simulated acid rain.

    Science.gov (United States)

    Andrade, Guilherme C; Silva, Luzimar C

    2017-07-01

    We investigated the morphological and anatomical effects of simulated acid rain on leaves of two species native to the Brazilian Atlantic Rainforest: Paubrasilia echinata and Libidibia ferrea var. leiostachya. Saplings were subjected to acid rain in a simulation chamber during 10 days for 15 min daily, using H 2 SO 4 solution pH 3.0 and, in the control, deionized water. At the end of the experiment, fragments from young and expanding leaves were anatomically analyzed. Although L. ferrea var. leiostachya leaves are more hydrophobic, rain droplets remained in contact with them for a longer time, as in the hydrophilic P. echinata leaves, droplets coalesce and rapidly run off. Visual symptomatology consisted in interveinal and marginal necrotic dots. Microscopic damage found included epicuticular wax flaking, turgor loss and epidermal cell shape alteration, hypertrophy of parenchymatous cells, and epidermal and mesophyll cell collapse. Formation of a wound tissue was observed in P. echinata, and it isolated the necrosis to the adaxial leaf surface. Acid rain increased thickness of all leaf tissues except spongy parenchyma in young leaves of L. ferrea var. leiostachya, and such thickness was maintained throughout leaf expansion. To our knowledge, this is the first report of acidity causing increase in leaf tissue thickness. This could represent the beginning of cell hypertrophy, which was seen in visually affected leaf regions. Paubrasilia echinata was more sensitive, showing earlier symptoms, but the anatomical damage in L. ferrea var. leiostachya was more severe, probably due to the higher time of contact with acid solution in this species.

  20. Seasonal radiogenic isotopic variability of the African dust outflow to the tropical Atlantic Ocean and across to the Caribbean

    Science.gov (United States)

    Kumar, Ashwini; Abouchami, W.; Galer, S. J. G.; Singh, Satinder Pal; Fomba, K. W.; Prospero, J. M.; Andreae, M. O.

    2018-04-01

    In order to assess the impact of mineral dust on climate and biogeochemistry, it is paramount to identify the sources of dust emission. In this regard, radiogenic isotopes have recently been used successfully for tracing North African dust provenance and its transport across the tropical Atlantic to the Caribbean. Here we present two time series of radiogenic isotopes (Pb, Sr and Nd) in dusts collected at the Cape Verde Islands and Barbados in order to determine the origin of the dust and examine the seasonality of westerly dust outflow from Northern Africa. Aerosol samples were collected daily during two campaigns - February 2012 (winter) and June-July 2013 (summer) - at the Cape Verde Atmospheric Observatory (CVAO) on the island of São Vicente (16.9°N, 24.9°W). A one-year-long time series of aerosols from Barbados (13.16°N, 59.43°W) - a receptor region in the Caribbean - was sampled at a lower, monthly resolution. Our results resolve a seasonal isotopic signal at Cape Verde shown by daily variations, with a larger radiogenic isotope variability in winter compared to that in summer. This summer signature is also observed over Barbados, indicating similar dust provenance at both locations, despite different sampling years. This constrains the isotope fingerprint of Saharan Air Layer (SAL) dust that is well-mixed during its transport. This result provides unequivocal evidence for a permanent, albeit of variable strength, long-range transport of African dust to the Caribbean and is in full agreement with atmospheric models of North African dust emission and transport across the tropical Atlantic in the SAL. The seasonal isotopic variability is related to changes in the dust source areas - mainly the Sahara and Sahel regions - that are active all-year-round, albeit with variable contributions in summer versus the winter months. Our results provide little support for much dust contributed from the Bodélé Depression in Chad - the "dustiest" place on Earth

  1. The Sorcerer II Global Ocean Sampling expedition: northwest Atlantic through eastern tropical Pacific.

    Directory of Open Access Journals (Sweden)

    Douglas B Rusch

    2007-03-01

    Full Text Available The world's oceans contain a complex mixture of micro-organisms that are for the most part, uncharacterized both genetically and biochemically. We report here a metagenomic study of the marine planktonic microbiota in which surface (mostly marine water samples were analyzed as part of the Sorcerer II Global Ocean Sampling expedition. These samples, collected across a several-thousand km transect from the North Atlantic through the Panama Canal and ending in the South Pacific yielded an extensive dataset consisting of 7.7 million sequencing reads (6.3 billion bp. Though a few major microbial clades dominate the planktonic marine niche, the dataset contains great diversity with 85% of the assembled sequence and 57% of the unassembled data being unique at a 98% sequence identity cutoff. Using the metadata associated with each sample and sequencing library, we developed new comparative genomic and assembly methods. One comparative genomic method, termed "fragment recruitment," addressed questions of genome structure, evolution, and taxonomic or phylogenetic diversity, as well as the biochemical diversity of genes and gene families. A second method, termed "extreme assembly," made possible the assembly and reconstruction of large segments of abundant but clearly nonclonal organisms. Within all abundant populations analyzed, we found extensive intra-ribotype diversity in several forms: (1 extensive sequence variation within orthologous regions throughout a given genome; despite coverage of individual ribotypes approaching 500-fold, most individual sequencing reads are unique; (2 numerous changes in gene content some with direct adaptive implications; and (3 hypervariable genomic islands that are too variable to assemble. The intra-ribotype diversity is organized into genetically isolated populations that have overlapping but independent distributions, implying distinct environmental preference. We present novel methods for measuring the genomic

  2. The ability of general circulation models to simulate tropical cyclones and their precursors over the North Atlantic main development region

    Energy Technology Data Exchange (ETDEWEB)

    Daloz, Anne Sophie; Chauvin, Fabrice [Groupe de Modelisation Grande Echelle et Climat, CNRM-GAME, Meteo-France, Toulouse Cedex 1 (France); Walsh, Kevin [University of Melbourne, School of Earth Sciences, Melbourne, VIC (Australia); Lavender, Sally; Abbs, Deborah [CSIRO Atmospheric and Marine Research, Aspendale, VIC (Australia); Roux, Frank [Universite de Toulouse and Centre National de la Recherche Scientifique, Laboratoire d' Aerologie, Toulouse (France)

    2012-10-15

    The ability of General Circulation Models (GCMs) to generate Tropical Cyclones (TCs) over the North Atlantic Main Development Region (MDR; 10-20 N, 20-80 W; Goldenberg and Shapiro in J Clim 9:1169-1187, 1996) is examined through a subset of ocean-atmosphere coupled simulations from the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel data set and a high-resolution (0.5 ) Sea Surface Temperature (SST)-forced simulation from the Australian Conformal-Cubic Atmospheric Model GCM. The results are compared with National Center for Environmental Prediction (NCEP-2) and European Center for Medium Range Weather Forecasts Re-Analysis (ERA-40) reanalyses over a common period from 1980 to 1998. Important biases in the representation of the TC activity are encountered over the MDR. This study emphasizes the strong link in the GCMs between African Easterly Waves (AEWs) and TC activity in this region. However, the generation of AEWs is not a sufficient condition alone for the models to produce TCs. Precipitation over the Sahel, especially rainfall over the Fouta Djallon highlands (cf. Fig. 1), is playing a role in the generation of TCs over the MDR. The influence of large-scale fields such as SST, vertical wind shear and tropospheric humidity on TC genesis is also examined. The ability of TC genesis indices, such as the Genesis Potential Index and the Convective Yearly Genesis Potential, to represent TC activity over the MDR in simulations at low to high spatial resolutions is analysed. These indices are found to be a reasonable method for comparing cyclogenesis in different models, even though other factors such as AEW activity should also be considered. (orig.)

  3. C5 glycolipids of heterocystous cyanobacteria track symbiont abundance in the diatom Hemiaulus hauckii across the tropical North Atlantic

    Directory of Open Access Journals (Sweden)

    N. J. Bale

    2018-03-01

    Full Text Available Diatom–diazotroph associations (DDAs include marine heterocystous cyanobacteria found as exosymbionts and endosymbionts in multiple diatom species. Heterocysts are the site of N2 fixation and have thickened cell walls containing unique heterocyst glycolipids which maintain a low oxygen environment within the heterocyst. The endosymbiotic cyanobacterium Richelia intracellularis found in species of the diatom genus Hemiaulus and Rhizosolenia makes heterocyst glycolipids (HGs which are composed of C30 and C32 diols and triols with pentose (C5 moieties that are distinct from limnetic cyanobacterial HGs with predominantly hexose (C6 moieties. Here we applied a method for analysis of intact polar lipids to the study of HGs in suspended particulate matter (SPM and surface sediment from across the tropical North Atlantic. The study focused on the Amazon plume region, where DDAs are documented to form extensive surface blooms, in order to examine the utility of C5 HGs as markers for DDAs as well as their transportation to underlying sediments. C30 and C32 triols with C5 pentose moieties were detected in both marine SPM and surface sediments. We found a significant correlation between the water column concentration of these long-chain C5 HGs and DDA symbiont counts. In particular, the concentrations of both the C5 HGs (1-(O-ribose-3,27,29-triacontanetriol (C5 HG30 triol and 1-(O-ribose-3,29,31-dotriacontanetriol (C5 HG32 triol in SPM exhibited a significant correlation with the number of Hemiaulus hauckii symbionts. This result strengthens the idea that long-chain C5 HGs can be applied as biomarkers for marine endosymbiotic heterocystous cyanobacteria. The presence of the same C5 HGs in surface sediment provides evidence that they are effectively transported to the sediment and hence have potential as biomarkers for studies of the contribution of DDAs to the paleo-marine N cycle.

  4. C5 glycolipids of heterocystous cyanobacteria track symbiont abundance in the diatom Hemiaulus hauckii across the tropical North Atlantic

    Science.gov (United States)

    Bale, Nicole J.; Villareal, Tracy A.; Hopmans, Ellen C.; Brussaard, Corina P. D.; Besseling, Marc; Dorhout, Denise; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2018-03-01

    Diatom-diazotroph associations (DDAs) include marine heterocystous cyanobacteria found as exosymbionts and endosymbionts in multiple diatom species. Heterocysts are the site of N2 fixation and have thickened cell walls containing unique heterocyst glycolipids which maintain a low oxygen environment within the heterocyst. The endosymbiotic cyanobacterium Richelia intracellularis found in species of the diatom genus Hemiaulus and Rhizosolenia makes heterocyst glycolipids (HGs) which are composed of C30 and C32 diols and triols with pentose (C5) moieties that are distinct from limnetic cyanobacterial HGs with predominantly hexose (C6) moieties. Here we applied a method for analysis of intact polar lipids to the study of HGs in suspended particulate matter (SPM) and surface sediment from across the tropical North Atlantic. The study focused on the Amazon plume region, where DDAs are documented to form extensive surface blooms, in order to examine the utility of C5 HGs as markers for DDAs as well as their transportation to underlying sediments. C30 and C32 triols with C5 pentose moieties were detected in both marine SPM and surface sediments. We found a significant correlation between the water column concentration of these long-chain C5 HGs and DDA symbiont counts. In particular, the concentrations of both the C5 HGs (1-(O-ribose)-3,27,29-triacontanetriol (C5 HG30 triol) and 1-(O-ribose)-3,29,31-dotriacontanetriol (C5 HG32 triol)) in SPM exhibited a significant correlation with the number of Hemiaulus hauckii symbionts. This result strengthens the idea that long-chain C5 HGs can be applied as biomarkers for marine endosymbiotic heterocystous cyanobacteria. The presence of the same C5 HGs in surface sediment provides evidence that they are effectively transported to the sediment and hence have potential as biomarkers for studies of the contribution of DDAs to the paleo-marine N cycle.

  5. Polyunsaturated fatty acids in various macroalgal species from North Atlantic and tropical seas.

    Science.gov (United States)

    van Ginneken, Vincent J T; Helsper, Johannes P F G; de Visser, Willem; van Keulen, Herman; Brandenburg, Willem A

    2011-06-22

    In this study the efficacy of using marine macroalgae as a source for polyunsaturated fatty acids, which are associated with the prevention of inflammation, cardiovascular diseases and mental disorders, was investigated. The fatty acid (FA) composition in lipids from seven sea weed species from the North Sea (Ulva lactuca, Chondrus crispus, Laminaria hyperborea, Fucus serratus, Undaria pinnatifida, Palmaria palmata, Ascophyllum nodosum) and two from tropical seas (Caulerpa taxifolia, Sargassum natans) was determined using GCMS. Four independent replicates were taken from each seaweed species. Omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFAs), were in the concentration range of 2-14 mg/g dry matter (DM), while total lipid content ranged from 7-45 mg/g DM. The n-9 FAs of the selected seaweeds accounted for 3%-56% of total FAs, n-6 FAs for 3%-32% and n-3 FAs for 8%-63%. Red and brown seaweeds contain arachidonic (C20:4, n-6) and/or eicosapentaenoic acids (EPA, C20:5, n-3), the latter being an important "fish" FA, as major PUFAs while in green seaweeds these values are low and mainly C16 FAs were found. A unique observation is the presence of another typical "fish" fatty acid, docosahexaenoic acid (DHA, C22:6, n-3) at ≈ 1 mg/g DM in S. natans. The n-6: n-3 ratio is in the range of 0.05-2.75 and in most cases below 1.0. Environmental effects on lipid-bound FA composition in seaweed species are discussed. Marine macroalgae form a good, durable and virtually inexhaustible source for polyunsaturated fatty acids with an (n-6) FA: (n-3) FA ratio of about 1.0. This ratio is recommended by the World Health Organization to be less than 10 in order to prevent inflammatory, cardiovascular and nervous system disorders. Some marine macroalgal species, like P. palmata, contain high proportions of the "fish fatty acid" eicosapentaenoic acid (EPA, C20:5, n-3), while in S. natans also docosahexaenoic acid (DHA, C22:6, n-3) was detected.

  6. Polyunsaturated fatty acids in various macroalgal species from north Atlantic and tropical seas

    Directory of Open Access Journals (Sweden)

    van Keulen Herman

    2011-06-01

    Full Text Available Abstract Background In this study the efficacy of using marine macroalgae as a source for polyunsaturated fatty acids, which are associated with the prevention of inflammation, cardiovascular diseases and mental disorders, was investigated. Methods The fatty acid (FA composition in lipids from seven sea weed species from the North Sea (Ulva lactuca, Chondrus crispus, Laminaria hyperborea, Fucus serratus, Undaria pinnatifida, Palmaria palmata, Ascophyllum nodosum and two from tropical seas (Caulerpa taxifolia, Sargassum natans was determined using GCMS. Four independent replicates were taken from each seaweed species. Results Omega-3 (n-3 and omega-6 (n-6 polyunsaturated fatty acids (PUFAs, were in the concentration range of 2-14 mg/g dry matter (DM, while total lipid content ranged from 7-45 mg/g DM. The n-9 FAs of the selected seaweeds accounted for 3%-56% of total FAs, n-6 FAs for 3%-32% and n-3 FAs for 8%-63%. Red and brown seaweeds contain arachidonic (C20:4, n-6 and/or eicosapentaenoic acids (EPA, C20:5, n-3, the latter being an important "fish" FA, as major PUFAs while in green seaweeds these values are low and mainly C16 FAs were found. A unique observation is the presence of another typical "fish" fatty acid, docosahexaenoic acid (DHA, C22:6, n-3 at ≈ 1 mg/g DM in S. natans. The n-6: n-3 ratio is in the range of 0.05-2.75 and in most cases below 1.0. Environmental effects on lipid-bound FA composition in seaweed species are discussed. Conclusion Marine macroalgae form a good, durable and virtually inexhaustible source for polyunsaturated fatty acids with an (n-6 FA: (n-3 FA ratio of about 1.0. This ratio is recommended by the World Health Organization to be less than 10 in order to prevent inflammatory, cardiovascular and nervous system disorders. Some marine macroalgal species, like P. palmata, contain high proportions of the "fish fatty acid" eicosapentaenoic acid (EPA, C20:5, n-3, while in S. natans also docosahexaenoic acid (DHA, C

  7. Marine sedimentary environments on some parts of the tropical and equatorial Atlantic margins of Africa during the Late Quaternary

    Science.gov (United States)

    Barusseau, J. P.; Giresse, P.; Faure, H.; Lezine, A. M.; Masse, J. P.

    1988-01-01

    From 18,000 y B.P. up to the Present, major climatic changes combined with eustatic sea-level irregular rise controlled important variations in sedimentary conditions on the Atlantic African margin between 6°S and 21°N. The present shelf deposition of material is also controlled by climatic latitudinal gradients acting on the nature, volume and distribution of terrigenous and carbonate sediments. The evolution of sedimentary conditions during this period may be summarized as follows. Coastal terrigenous deposition Fluvial sands were emplaced in inner shelf paleo-valleys during the beginning of the Wiscon sinian regression, following a major erosion phase providing an important source for the siliciclastic part of the terrigenous influx. In tropical regions (Mauritania, Senegal), aeolian dune sands formed during the arid "glacial" period (the so-called Ogolian) on the emerged shelf, but were destroyed during the subsequent transgression. In the vicinity and south of the Equator (Coˆte d'Ivoire, Congo), aeolian input was reduced but litoral dunes of that period occurred whose remnants may be observed close to the present shoreline. At the lower stand of sea level, fine particles directly by-passed the shelf towards the continental rises and abyssal plains. During the Holocene transgression, the main sedimentary processes occurred only when standstill or slowing of the sea-level rise took place. Then littoral deposits (fine sands of the shore, dune sands and even lagoonal deposits with mangrove peats) accumulated still more or less visible paleo-shorelines. However, offshore from the equatorial river mouths, particularly the main ones (Congo), pelitic sediments settled in morphological and structural lows. High sedimentation rates were common at the beginning but they decreased during the final part of the transgression. In the tropical region terrigenous fluvial input is considerably reduced but, in their northernmost parts, aeolian contribution of silts and

  8. Decapod assemblages in subtidal and intertidal zones—Importance of scuba diving as a survey technique in tropical reefs, Brazil

    OpenAIRE

    Giraldes, Bruno Welter; Coelho Filho, Petrônio Alves; Smyth, David Mark

    2015-01-01

    Decapods play a crucial role within the reef ecosystem and the development of scuba diving as a survey tool has allowed researchers the opportunity to study the decapod–reef relationship more comprehensively. The present study describes the differences in decapod assemblages in intertidal and subtidal zones at a tropical coastal reef system in the southwestern Atlantic Ocean and reports the importance of scuba diving as a survey technique. A total of 71 decapods were recorded during the resea...

  9. On the Relationship Between the Length of Season and Tropical Cyclone Activity in the North Atlantic Basin During the Weather Satellite Era, 1960-2013

    Science.gov (United States)

    Wilson, Robert M.

    2014-01-01

    Officially, the North Atlantic basin tropical cyclone season runs from June 1 through November 30 of each year. During this 183-day interval, the vast majority of tropical cyclone onsets are found to occur. For example, in a study of the 715 tropical cyclones that occurred in the North Atlantic basin during the interval 1945-2010, it was found that about 97 percent of them had their onsets during the conventional hurricane season, with the bulk (78 percent) having had onset during the late summer-early fall months of August, September, and October and with none having had onset in the month of March. For the 2014 hurricane season, it already has had the onset of its first named storm on July 1 (day of year (DOY) 182), Arthur, which formed off the east coast of Florida, rapidly growing into a category-2 hurricane with peak 1-minute sustained wind speed of about 90 kt and striking the coast of North Carolina as a category-2 hurricane on July 3. Arthur is the first hurricane larger than category-1 to strike the United States (U.S.) since the year 2008 when Ike struck Texas as a category-2 hurricane and there has not been a major hurricane (category-3 or larger) to strike the U.S. since Wilma struck Florida as a category-3 hurricane in 2005. Only two category-1 hurricanes struck the U.S. in the year 2012 (Isaac and Sandy, striking Louisiana and New York, respectively) and there were no U.S. land-falling hurricanes in 2013 (also true for the years 1962, 1973, 1978, 1981, 1982, 1990, 1994, 2000, 2001, 2006, 2009, and 2010). In recent years it has been argued that the length of season (LOS), determined as the inclusive elapsed time between the first storm day (FSD) and the last storm day (LSD) of the yearly hurricane season (i.e., when peak 1-minute sustained wind speed of at least 34 kt occurred and the tropical cyclone was not classified as 'extratropical'), has increased in length with the lengthening believed to be due to the FSD occurring sooner and the LSD occurring

  10. Comparative Characterisation of Maritime Clouds between Dry and Wet Season Over the Tropical North Atlantic by Airborne Observations

    Science.gov (United States)

    Jacob, Marek; Ament, Felix; Crewell, Susanne; Ehrlich, André; Wolf, Kevin; Mech, Mario; Orlandi, Emiliano; Schnitt, Sabrina

    2017-04-01

    Trade wind clouds are a major uncertainty in climate models. The observation of these clouds by satellites is limited by the satellite resolution and detailed ground-based observations are lacking. Therefore, the series of Next-Generation Aircraft Remote-Sensing for Validation campaigns (NARVAL) using the High Altitude LOng range research aircraft (HALO) was initiated to assess North Atlantic trade clouds on an appropriate scale. In this presentation, we take the advantage of the synergy of the HALO active and passive Microwave Package (HAMP) in combination with the solar radiation measured by the Spectral Modular Airborne Radiation measurement system (SMART) to characterize shallow clouds in the Caribbean. The two NARVAL campaigns in December 2013 and August 2016 offer the opportunity to study clouds during dry and wet season, respectively. Based on a cloud mask derived from SMART spectral solar measurements, about 12000 cloudy profiles describing 4100 individual clouds could be detected during the dry season (NARVAL-I) with about 70% of the clouds having a length of less than 2 km. Corresponding retrieval of the liquid water path (LWP) using passive microwave measurements reveals that these small clouds contain little water with a third of the clouds having a LWP of less than 50 g m-2. Such small clouds are difficult to measure by the spaceborne Special Sensor Microwave Imager/Sounder (SSMIS) due to its coarse resolution while precipitable water vapor agrees rather well between airborne and satellite measurements. Using a simple reflectivity threshold, 7% of the clouds were identified as precipitating. Precipitation did not show a strong dependence on LWP and there were also precipitating clouds showing a LWP lower than 100 g m-2. While the Moderate Imaging Spectroradiometer (MODIS) is able to identify smaller clouds (˜ 1 km), it shows deficits in terms of LWP for drizzling clouds. This presentation addresses differences in cloud characteristics between the

  11. Asymmetric response of tropical cyclone activity to global warming over the North Atlantic and western North Pacific from CMIP5 model projections.

    Science.gov (United States)

    Park, Doo-Sun R; Ho, Chang-Hoi; Chan, Johnny C L; Ha, Kyung-Ja; Kim, Hyeong-Seog; Kim, Jinwon; Kim, Joo-Hong

    2017-01-30

    Recent improvements in the theoretical understanding of the relationship between tropical cyclones (TCs) and their large-scale environments have resulted in significant improvements in the skill for forecasting TC activity at daily and seasonal time-scales. However, future changes in TC activity under a warmer climate remain uncertain, particularly in terms of TC genesis locations and subsequent pathways. Applying a track-pattern-based statistical model to 22 Coupled Model Intercomparison Project Phase 5 (CMIP5) model runs for the historical period and the future period corresponding to the Representative Concentration Pathway 8.5 emissions scenarios, this study shows that in future climate conditions, TC passage frequency will decrease over the North Atlantic, particularly in the Gulf of Mexico, but will increase over the western North Pacific, especially that hits Korea and Japan. Unlike previous studies based on fine-resolution models, an ensemble mean of CMIP5 models projects an increase in TC activity in the western North Pacific, which is owing to enhanced subtropical deep convection and favorable dynamic conditions therein in conjunction with the expansion of the tropics and vice versa for the North Atlantic. Our results suggest that North America will experience less TC landfalls, while northeast Asia will experience more TCs than in the present-day climate.

  12. Asymmetric response of tropical cyclone activity to global warming over the North Atlantic and western North Pacific from CMIP5 model projections

    Science.gov (United States)

    Park, Doo-Sun R.; Ho, Chang-Hoi; Chan, Johnny C. L.; Ha, Kyung-Ja; Kim, Hyeong-Seog; Kim, Jinwon; Kim, Joo-Hong

    2017-01-01

    Recent improvements in the theoretical understanding of the relationship between tropical cyclones (TCs) and their large-scale environments have resulted in significant improvements in the skill for forecasting TC activity at daily and seasonal time-scales. However, future changes in TC activity under a warmer climate remain uncertain, particularly in terms of TC genesis locations and subsequent pathways. Applying a track-pattern-based statistical model to 22 Coupled Model Intercomparison Project Phase 5 (CMIP5) model runs for the historical period and the future period corresponding to the Representative Concentration Pathway 8.5 emissions scenarios, this study shows that in future climate conditions, TC passage frequency will decrease over the North Atlantic, particularly in the Gulf of Mexico, but will increase over the western North Pacific, especially that hits Korea and Japan. Unlike previous studies based on fine-resolution models, an ensemble mean of CMIP5 models projects an increase in TC activity in the western North Pacific, which is owing to enhanced subtropical deep convection and favorable dynamic conditions therein in conjunction with the expansion of the tropics and vice versa for the North Atlantic. Our results suggest that North America will experience less TC landfalls, while northeast Asia will experience more TCs than in the present-day climate.

  13. Fish Species in a Changing World: The Route and Timing of Species Migration between Tropical and Temperate Ecosystems in Eastern Atlantic.

    Directory of Open Access Journals (Sweden)

    Awaluddin Halirin Kaimuddin

    2016-09-01

    Full Text Available The presence of tropical species has been reported in Atlantic-European waters with increasing frequency in recent years. Unfortunately, the history of their migrations is not well understood. In this study, we examined the routes and timing of fish migrations in several ecosystems of the East Atlantic Ocean, combining several publicly available and unpublicized datasets on species occurrences. The species studied were those noted as exotic or rare outside their previous known area of distribution. We used sea surface temperature (SST data obtained from 30 years of satellite observation to define three distinct time periods. Within these periods, temperature trends were studied in six ecosystems: the North Sea, the Celtic Sea, the South European Atlantic Waters, the Mediterranean Sea, the Canary Current and the Guinea Current. We also incorporated bathymetry data to describe the distribution of species. Measurement across a relatively large spatial extent was made possible by incorporating the capabilities of GIS.While SST increased consistently over time in all of the ecosystems observed, the change in number of species differed among ecosystems. The number of species in the middle regions, such as the South European Atlantic Shelf and the Western Mediterranean Sea, tended to increase over time. These regions received numbers of species from the lower or the upper latitudes according to season. Of all of the species observed in the recent period, 7 species from the Canary Current tended to be found in the Western Mediterranean Sea, and 6 species from these two regions extended their distributions to the South European Atlantic Shelf. Twelve species from the Canary Current moved seasonally to the Guinea Current. In the northern regions, 13 species moved seasonally in the North Sea and the Celtic Seas, and 12 of these species reached the South European Atlantic Shelf.This study presents a picture of routes and timing of species migration at the

  14. Inter-annual variability of aerosol optical depth over the tropical Atlantic Ocean based on MODIS-Aqua observations over the period 2002-2012

    Science.gov (United States)

    Gkikas, Antonis; Hatzianastassiou, Nikolaos

    2013-04-01

    The tropical Atlantic Ocean is affected by dust and biomass burning aerosol loads transported from the western parts of the Saharan desert and the sub-Sahel regions, respectively. The spatial and temporal patterns of this transport are determined by the aerosol emission rates, their deposition (wet and dry), by the latitudinal shift of the Intertropical Convergence Zone (ITCZ) and the prevailing wind fields. More specifically, in summer, Saharan dust aerosols are transported towards the Atlantic Ocean, even reaching the Gulf of Mexico, while in winter the Atlantic Ocean transport takes place in more southern latitudes, near the equator, sometimes reaching the northern parts of South America. In the later case, dust is mixed with biomass burning aerosols originating from agricultural activities in the sub-Sahel, associated with prevailing north-easterly airflow (Harmattan winds). Satellite observations are the appropriate tool for describing this African aerosol export, which is important to atmospheric, oceanic and climate processes, offering the advantage of complete spatial coverage. In the present study, we use satellite measurements of aerosol optical depth at 550nm (AOD550nm), on a daily and monthly basis, derived from MODIS-Aqua platform, at 1ox1o spatial resolution (Level 3), for the period 2002-2012. The primary objective is to determine the pixel-level and regional mean anomalies of AOD550nm over the entire study period. The regime of the anomalies of African export is interpreted in relation to the aerosol source areas, precipitation, wind patterns and temporal variability of the North Atlantic Oscillation Index (NAOI). In order to ensure availability of AOD over the Sahara desert, MODIS-Aqua Deep Blue products are also used. As for precipitation, Global Precipitation Climatology Project (GPCP) data at 2.5ox2.5o are used. The wind fields are taken from the National Center for Environmental Prediction (NCEP). Apart from the regime of African aerosol export

  15. A Multi-Scale Analysis of Tropical Cyclogenesis Within the Critical Layer of Tropical Easterly Waves in the Atlantic and Western North Pacific Sectors

    Science.gov (United States)

    2010-09-01

    Formation of Atlantic hurricanes from cloud clusters and depressions. J. Atmos. Sci., 47, 909–927. Chang, C. P., V. F. Morris, and J. M. Wallace , 1970: A...Scale interactions during the formation of Typhoon Irving . Mon. Wea. Rev., 125, 1377–1396. Ritchie, E. A., and G. J. Holland, 1999: Large-scale

  16. Links between viral and prokaryotic communities throughout the water column in the (sub)tropical Atlantic Ocean

    NARCIS (Netherlands)

    De Corte, Daniele; Sintes, Eva; Winter, Christian; Yokokawa, Taichi; Reinthaler, Thomas; Herndl, Gerhard J.

    2010-01-01

    Viral and prokaryotic abundance, production and diversity were determined throughout the water column of the subtropical Atlantic Ocean to assess potential variations in the relation between viruses and prokaryotes. Prokaryotic abundance and heterotrophic activity decreased by one and three orders

  17. A Swiss Village in the Dutch Tropics: The Limitations of Empire-Centred Approaches to the Early Modern Atlantic World

    Directory of Open Access Journals (Sweden)

    Karwan Fatah-Black

    2013-03-01

    Full Text Available This article considers what the migration circuits to and from Suriname can tell us about Dutch early modern colonisation in the Atlantic world. Did the Dutch have an Atlantic empire that can be studied by treating it as an integrated space, as suggested by New Imperial Historians, or did colonisation rely on circuits outside Dutch control, stretching beyond its imperial space? An empire-centred approach has dominated the study of Suriname’s history and has largely glossed over the routes taken by European migrants to and from the colony. When the empirecentred perspective is transcended it becomes possible to see that colonists arrived in Suriname from a range of different places around the Atlantic and the European hinterland. The article takes an Atlantic or global perspective to demonstrate the choices available to colonists and the networks through which they moved.

  18. New records of coastal fishes in the northern Rio de Janeiro State, Brazil, with comments on the biogeography of the south-western Atlantic Ocean.

    Science.gov (United States)

    Di Dario, F; Petry, A C; Mincarone, M M; Pereira, M M S; dos Santos, R M

    2011-08-01

    The distribution limits in the Atlantic of Callorhinchus callorynchus (Callorhinchidae) and Odontesthes argentinensis (Atherinopsidae) are extended northwards to 22° 22' S and 22° 31' S, respectively, whereas that of Lile piquitinga (Clupeidae) is extended southwards to 22° 22' S. Their occurrence in the north of Rio de Janeiro State is discussed. Remarks on the osteology of O. argentinensis, and morphometric and meristic data of L. piquitinga, are also provided. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.

  19. Silicate:nitrate ratios of upwelled waters control the phytoplankton community sustained by mesoscale eddies in sub-tropical North Atlantic and Pacific

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    T. S. Bibby

    2011-03-01

    Full Text Available Mesoscale eddies in sub-tropical gyres physically perturb the water column and can introduce macronutrients to the euphotic zone, stimulating a biological response in which phytoplankton communities can become dominated by large phytoplankton. Mesoscale eddies may therefore be important in driving export in oligotrophic regions of the modern ocean. However, the character and magnitude of the biological response sustained by eddies is variable. Here we present data from mesoscale eddies in the Sargasso Sea (Atlantic and the waters off Hawai'i (Pacific, alongside mesoscale events that affected the Bermuda Atlantic Time-Series Study (BATS over the past decade. From this analysis, we suggest that the phytoplankton community structure sustained by mesoscale eddies is predetermined by the relative abundance of silicate over nitrate (Si* in the upwelled waters. We present data that demonstrate that mode-water eddies (MWE in the Sargasso Sea upwell locally formed waters with relatively high Si* to the euphotic zone, and that cyclonic eddies in the Sargasso Sea introduce waters with relatively low Si*, a signature that originated in the iron-limited Southern Ocean. We propose that this phenomenon can explain the observed dominance of the phytoplankton community by large-diatom species in MWE and by small prokaryotic phytoplankton in cyclonic features. In contrast to the Atlantic, North Pacific Intermediate Water (NPIW with high Si* may influence the cyclonic eddies in waters off Hawai'i, which also appear capable of sustaining diatom populations. These observations suggest that the structure of phytoplankton communities sustained by eddies may be related to the chemical composition of the upwelled waters in addition to the physical nature of the eddy.

  20. Alleviating tropical Atlantic sector biases in the Kiel climate model by enhancing horizontal and vertical atmosphere model resolution: climatology and interannual variability

    Science.gov (United States)

    Harlaß, Jan; Latif, Mojib; Park, Wonsun

    2018-04-01

    We investigate the quality of simulating tropical Atlantic (TA) sector climatology and interannual variability in integrations of the Kiel climate model (KCM) with varying atmosphere model resolution. The ocean model resolution is kept fixed. A reasonable simulation of TA sector annual-mean climate, seasonal cycle and interannual variability can only be achieved at sufficiently high horizontal and vertical atmospheric resolution. Two major reasons for the improvements are identified. First, the western equatorial Atlantic westerly surface wind bias in spring can be largely eliminated, which is explained by a better representation of meridional and especially vertical zonal momentum transport. The enhanced atmospheric circulation along the equator in turn greatly improves the thermal structure of the upper equatorial Atlantic with much reduced warm sea surface temperature (SST) biases. Second, the coastline in the southeastern TA and steep orography are better resolved at high resolution, which improves wind structure and in turn reduces warm SST biases in the Benguela upwelling region. The strongly diminished wind and SST biases at high atmosphere model resolution allow for a more realistic latitudinal position of the intertropical convergence zone. Resulting stronger cross-equatorial winds, in conjunction with a shallower thermocline, enable a rapid cold tongue development in the eastern TA in boreal spring. This enables simulation of realistic interannual SST variability and its seasonal phase locking in the KCM, which primarily is the result of a stronger thermocline feedback. Our findings suggest that enhanced atmospheric resolution, both vertical and horizontal, could be a key to achieving more realistic simulation of TA climatology and interannual variability in climate models.

  1. Aerosol time-series measurements over the tropical Northeast Atlantic Ocean: Dust sources, elemental composition and mineralogy

    NARCIS (Netherlands)

    Patey, M.D.; Achterberg, E.P.; Rijkenberg, M.J.; Pearce, R.

    2015-01-01

    The North Atlantic receives the largest dust loading of any of the world's oceans due to its proximity to North African deserts and prevailing wind patterns. The supply of biologically important trace elements and nutrients via aerosols has an important influence on biogeochemical processes and

  2. Dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using WRF-Chem coupled with an AOD data assimilation system

    Science.gov (United States)

    Chen, Dan; Liu, Zhiquan; Davis, Chris; Gu, Yu

    2017-06-01

    This study investigated the dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using the Weather Research and Forecasting Model with Chemistry (WRF-Chem) coupled with an aerosol data assimilation (DA) system. MODIS AOD (aerosol optical depth) data were assimilated with the Gridpoint Statistical Interpolation (GSI) three-dimensional variational (3DVAR) DA scheme to depict the Saharan dust outbreak events in the 2006 summer. Comparisons with Ozone Monitoring Instrument (OMI), AErosol RObotic NETwork (AERONET), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations showed that the system was capable of reproducing the dust distribution. Two sets of 180 h forecasts were conducted with the dust radiative effects activated (RE_ON) and inactivated (RE_OFF) respectively. Differences between the RE_ON and RE_OFF forecasts showed that low-altitude (high-altitude) dust inhibits (favors) convection owing to changes in convective inhibition (CIN). Heating in dust layers immediately above the boundary layer increases inhibition, whereas sufficiently elevated heating allows cooling above the boundary layer that reduces convective inhibition. Semi-direct effects in which clouds are altered by thermodynamic changes are also noted, which then alter cloud-radiative temperature (T) changes. The analysis of a tropical cyclone (TC) suppression case on 5 September shows evidence of enhanced convective inhibition by direct heating in dust, but it also suggests that the low-predictability dynamics of moist convection reduces the determinism of the effects of dust on timescales of TC development (days).

  3. Abundance of small mammals in the Atlantic Forest (ASMAF): a data set for analyzing tropical community patterns.

    Science.gov (United States)

    Figueiredo, Marcos S L; Barros, Camila S; Delciellos, Ana C; Guerra, Edú B; Cordeiro-Estrela, Pedro; Kajin, Maja; Alvarez, Martin R; Asfora, Paulo H; Astúa, Diego; Bergallo, Helena G; Cerqueira, Rui; Geise, Lena; Gentile, Rosana; Grelle, Carlos Eduardo V; Iack-Ximenes, Gilson E; Oliveira, Leonardo C; Weksler, Marcelo; Vieira, Marcus V

    2017-11-01

    Local abundance results from the interaction between populational and environmental processes. The abundance of the species in a community is also one of the most basic descriptors of its structure. Despite its importance, information about species abundances is fragmentary, creating a knowledge gap about species abundances known as the Prestonian Shortfall. Here we present a comprehensive data set of small mammal abundance in the Atlantic Forest. Data were extracted from 114 published sources and from unpublished data collected by our research groups spanning from 1943 to 2017. The data set includes 1,902 records of at least 111 species in 155 localities, totaling 42,617 individuals represented. We selected studies that (1) were conducted in forested habitats of the Atlantic Forest, (2) had a minimum sampling effort of at least 500 trap-nights, and (3) contained species abundance data in detail. For each study, we recorded (1) latitude and longitude, (2) name of the locality, (3) employed sampling effort, (4) type of traps used, (5) study year, (6) country, and (7) species name with (8) its respective abundances. For every locality, we also obtained information regarding its (9) ecoregion, (10) predominant vegetation type, and (11) biogeographic subdivision. Whenever necessary, we also (12) updated the species names as new species were described and some genera suffered taxonomic revision since the publication. The localities are spread across the Atlantic Forest and most of the small mammal species known to occur in Atlantic Forest are present in the data set, making it representative of communities of the entire biome. This data set can be used to address various patterns in community ecology and geographical ecology, as the relation between local abundance and environmental suitability, hypothesis regarding local and regional factors on community structuring, species abundance distributions (SAD), functional and phylogenetic mechanisms on community assembling

  4. On the Current Trend of Tropical Cyclone Activity and the Lengthening of the Tropical Cyclone Season in the North Atlantic Basin

    Science.gov (United States)

    Wilson, Robert M.

    2013-01-01

    In this TP, the trend in North Atlantic basin TC activity, especially as related to the determination of the length of season (LOS) and its possible association with warming surface-air and sea-surface temperature, is revisited. In particular, examined are: (1) the trend in TC activity for the yearly intervals 1945-1965, 1966-1994, and 1995-2012 for TCs having duration NSD greater or equal to 0.25 day, less than 2 days, greater than or equal to 2 days, greater than or equal to 4 days, and greater than or equal to 8 days; (2) the latitudinal and longitudinal genesis locations of the short-lived TC (defined herein as those TCs having duration NSD less than 2 days) for the three yearly intervals; (3) the first storm day (FSD), last storm day (LSD), and LOS based on TCs having duration NSD greater than or equal to 0.25 day and NSD greater than or equal to 2 days; (4) the relationship between FSD, LSD, and LOS for TCs having duration NSD greater than or equal to 0.25 day and NSD greater than or equal to 2 days; (5) the surface-air and sea-surface temperature, wind, and North Atlantic Oscillation (NAO) during the interval 1945-2012; (6) the relationship of FSD, LSD, and LOS against surface-air and sea-surface temperature, wind, and the NAO; (7) the relationship of TC activity against surface-air and sea-surface temperature, wind, and the NAO; and (8) the relationship of TC activity against FSD and LOS. This TP represents an update to an earlier study by Wilson concerning the length of the yearly hurricane season.

  5. A switch in the Atlantic Oscillation correlates with inter-annual changes in foraging location and food habits of Macaronesian shearwaters (Puffinus baroli) nesting on two islands of the sub-tropical Atlantic Ocean

    Science.gov (United States)

    Ramos, Jaime A.; Isabel Fagundes, Ana; Xavier, José C.; Fidalgo, Vera; Ceia, Filipe R.; Medeiros, Renata; Paiva, Vitor H.

    2015-10-01

    Changes in oceanographic conditions, shaped by changes in large-scale atmospheric phenomena such as the North Atlantic Oscillation (NAO), alters the structure and functioning of marine ecosystems. Such signals are readily captured by marine top predators, given that their use of foraging habitats and diets change when the NAO changes. In this study we assessed sexual, seasonal and annual (2010/11-2012/13) differences in diet, trophic and isotopic niche (using δ15N and δ13C values of whole blood, 1st primary, 8th secondary and breast feathers), foraging locations and oceanographic variation within foraging areas for Macaronesian shearwaters' (Puffinus baroli) during two years of contrasting NAO values, and between two sub-tropical islands 330 km apart in the North Atlantic Ocean, Cima Islet and Selvagem Grande. These two locations provide contrasting oceanographic foraging regimes for the birds, because the second colony is much closer to the African coast (375 vs 650 km), and, therefore, to the upwelling area of the Canary Current. There was a marked environmental perturbation in 2010/2011, related with a negative NAO Index and lower marine productivity (lower concentration of Chlorophyll a). This event corresponded to the Macaronesian shearwaters feeding farther north and west, which was readily seen in change of both δ15N and δ13C values, and in a higher intake of cephalopods. Diet and stable isotopes did not differ between sexes. Regurgitation analysis indicate a dominance of cephalopods in both islands, but prey fish were important for Selvagem Grande in 2012 and cephalopods for Cima Islet in 2011. Both δ15N and δ13C values were significantly higher for Cima Islet than for Selvagem Grande, irrespective of year, season and tissue sampled. SIBER analysis showed smaller isotopic niches for the breeding period. Our study suggests that during years of poor environmental conditions Macaronesian shearwaters shift their foraging location to more pelagic waters

  6. Two new species of Syndesmis (Platyhelminthes, Rhabdocoela, Umagillidae from the sea urchin Pseudechinus magellanicus (Echinodermata, Echinoidea in the Southwestern Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Francisco Brusa

    2017-08-01

    Full Text Available In this paper, we describe two new species of Syndesmis living in Pseudechinus magellanicus in the Southwest Atlantic Ocean. The new species have a long stylet in the male reproductive system, which is different from that of the known species of the genus. Specimens of Syndesmis selknami n. sp. have a ∼220-μm-long stylet (∼1/3 of the body length, 0.69 mm. This ratio is unique because only four species (Syndesmis echinorum, Syndesmis rubida, Syndesmis inconspicua and Syndesmis echiniacuti have similar stylet lengths but are larger in body sizes (3–5 mm. Specimens of Syndesmis aonikenki n. sp. have a ∼148-μm-long stylet (∼1/10 of the body length, 1.11 mm. Syndesmis pallida has a similar ratio but the uterus is located posteriorly, and the filament glands are very small and located in the posterior region of the body. These are the first flatworms reported parasitizing Pseudechinus magellanicus.

  7. Throughfall and temporal trends of rainfall redistribution in an open tropical rainforest, south-western Amazonia (Rondônia, Brazil

    Directory of Open Access Journals (Sweden)

    S. Germer

    2006-01-01

    Full Text Available Throughfall volumes and incident rainfall were measured between 23 August and 2 December 2004 as well as from 6 January to 15 April 2005 for individual rain events of differing intensities and magnitudes in an open tropical rainforest in Rondônia, Brazil. Temporal patterns of throughfall spatial variability were examined. Estimated interception was compared to modeled interception obtained by applying the revised Gash model in order to identify sources of throughfall variability in open tropical rainforests. Gross precipitation of 97 events amounted to 1309 mm, 89±5.6% (S.E. of which reached the forest floor as throughfall. The redistribution of water within the canopy was highly variable in time, which we attribute to the high density of babassu palms (Orbignya phalerata, their seasonal leaf growth, and their conducive morphology. We identified a 10-min rainfall intensity threshold of 30 mmh-1 above which interception was highly variable. This variability is amplified by funneling and shading effects of palms. This interaction between a rainfall variable and vegetation characteristics is relevant for understanding the hydrology of all tropical rainforests with a high palm density.

  8. Turtle cleaners: reef fishes foraging on epibionts of sea turtles in the tropical Southwestern Atlantic, with a summary of this association type

    Directory of Open Access Journals (Sweden)

    Cristina Sazima

    2010-03-01

    Full Text Available In the present study we record several instances of reef fish species foraging on epibionts of sea turtles (cleaning symbiosis at the oceanic islands of Fernando de Noronha Archipelago and near a shipwreck, both off the coast of Pernambuco State, northeast Brazil. Nine reef fish species and three turtle species involved in cleaning are herein recorded. Besides our records, a summary of the literature on this association type is presented. Postures adopted by turtles during the interaction are related to the habits of associated fishes. Feeding associations between fishes and turtles seem a localized, albeit common, phenomenon.No presente estudo registramos diversos episódios de peixes recifais alimentando-se de epibiontes sobre o corpo de tartarugas marinhas (simbiose de limpeza nas ilhas oceânicas do arquipélago de Fernando de Noronha e próximo a um naufrágio na costa de Pernambuco, nordeste do Brasil. Nove espécies de peixes recifais e três espécies de tartarugas envolvidas nas associações são aqui registradas. Além de nossos registros, apresentamos também um resumo da literatura sobre o tema. As posturas adotadas pelas tartarugas durante as interações estão relacionadas com os hábitos dos peixes associados. Associações alimentares entre peixes e tartarugas podem ser consideradas como um fenômeno local, embora comum.

  9. Turtle cleaners: reef fishes foraging on epibionts of sea turtles in the tropical Southwestern Atlantic, with a summary of this association type

    Directory of Open Access Journals (Sweden)

    Cristina Sazima

    Full Text Available In the present study we record several instances of reef fish species foraging on epibionts of sea turtles (cleaning symbiosis at the oceanic islands of Fernando de Noronha Archipelago and near a shipwreck, both off the coast of Pernambuco State, northeast Brazil. Nine reef fish species and three turtle species involved in cleaning are herein recorded. Besides our records, a summary of the literature on this association type is presented. Postures adopted by turtles during the interaction are related to the habits of associated fishes. Feeding associations between fishes and turtles seem a localized, albeit common, phenomenon.

  10. On the Sizes of the North Atlantic Basin Tropical Cyclones Based on 34- and 64-kt Wind Radii Data, 2004-2013

    Science.gov (United States)

    Wilson, Robert M.

    2014-01-01

    At end of the 2012 hurricane season the National Hurricane Center retired the original HURDAT dataset and replaced it with the newer version HURDAT2, which reformatted the original data and included additional information, in particular, estimates of the 34-, 50, and 64-kt wind radii for the interval 2004-2013. During the brief 10-year interval, some 164 tropical cyclones are noted to have formed in the North Atlantic basin, with 77 becoming hurricanes. Hurricane Sandy (2012) stands out as being the largest individual storm that occurred in the North Atlantic basin during the 2004 -2013 timeframe, both in terms of its 34- and 64-kt wind radii and wind areas, having maximum 34- and 64-kt wind radii, maximum wind areas, and average wind areas each more than 2 standard deviations larger than the corresponding means. In terms of the largest yearly total 34-kt wind area (i.e., the sum of all individual storm 34-kt wind areas during the year), the year 2010 stands out as being the largest (about 423 × 10(exp 6) nmi(exp 2)), compared to the mean of about 174 × 10(exp 6) nmi(exp 2)), surpassing the year 2005 (353 x 10(exp 6) nmi(exp 2)) that had the largest number of individual storms (28). However, in terms of the largest yearly total 64-kt wind area, the year 2005 was the largest (about 9 × 10(exp 6) nmi(exp 2)), compared to the mean of about 3 × 106 nmi(exp 2)). Interesting is that the ratio of total 64-kt wind area to total 34-kt wind area has decreased over time, from 0.034 in 2004 to 0.008 in 2013.

  11. Large-Scale Examination of Spatio-Temporal Patterns of Drifting Fish Aggregating Devices (dFADs from Tropical Tuna Fisheries of the Indian and Atlantic Oceans.

    Directory of Open Access Journals (Sweden)

    Alexandra Maufroy

    Full Text Available Since the 1990s, massive use of drifting Fish Aggregating Devices (dFADs to aggregate tropical tunas has strongly modified global purse-seine fisheries. For the first time, a large data set of GPS positions from buoys deployed by French purse-seiners to monitor dFADs is analysed to provide information on spatio-temporal patterns of dFAD use in the Atlantic and Indian Oceans during 2007-2011. First, we select among four classification methods the model that best separates "at sea" from "on board" buoy positions. A random forest model had the best performance, both in terms of the rate of false "at sea" predictions and the amount of over-segmentation of "at sea" trajectories (i.e., artificial division of trajectories into multiple, shorter pieces due to misclassification. Performance is improved via post-processing removing unrealistically short "at sea" trajectories. Results derived from the selected model enable us to identify the main areas and seasons of dFAD deployment and the spatial extent of their drift. We find that dFADs drift at sea on average for 39.5 days, with time at sea being shorter and distance travelled longer in the Indian than in the Atlantic Ocean. 9.9% of all trajectories end with a beaching event, suggesting that 1,500-2,000 may be lost onshore each year, potentially impacting sensitive habitat areas, such as the coral reefs of the Maldives, the Chagos Archipelago, and the Seychelles.

  12. An ensemble estimation of the variability of upper-ocean heat content over the tropical Atlantic Ocean with multi-ocean reanalysis products

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Jieshun [Institute of Global Environment and Society, Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); Huang, Bohua [Institute of Global Environment and Society, Center for Ocean-Land-Atmosphere Studies, Calverton, MD (United States); George Mason University, Department of Atmospheric, Oceanic, and Earth Sciences, College of Science, Fairfax, VA (United States); Balmaseda, Magdalena A. [European Center for Medium-Range Weather Forecasts, Reading (United Kingdom)

    2012-08-15

    Current ocean reanalysis systems contain considerable uncertainty in estimating the subsurface oceanic state, especially in the tropical Atlantic Ocean. Given this level of uncertainty, it is important to develop useful strategies to identify realistic low-frequency signals optimally from these analyses. In this paper, we present an ''ensemble'' method to estimate the variability of upper-ocean heat content (HC) in the tropical Atlantic based on multiple-ocean reanalysis products. Six state-of-the-art global ocean reanalysis products, all of which are widely used in the climate research community, are examined in terms of their HC variability from 1979 to 2007. The conventional empirical orthogonal function (EOF) analysis of the HC anomalies from each individual analysis indicates that their leading modes show significant qualitative differences among analyses, especially for the first modes, although some common characteristics are discernable. Then, the simple arithmetic average (or ensemble mean) is applied to produce an ensemble dataset, i.e., the EM analysis. The leading EOF modes of the EM analysis show quantitatively consistent spatial-temporal patterns with those derived from an alternative EOF technique that maximizes signal-to-noise ratio of the six analyses, which suggests that the ensemble mean generates HC fields with the noise reduced to an acceptable level. The quality of the EM analysis is further validated against AVISO altimetry sea level anomaly (SLA) data and PIRATA mooring station data. A regression analysis with the AVISO SLA data proved that the leading modes in the EM analysis are realistic. It also demonstrated that some reanalysis products might contain higher level of intrinsic noise than others. A quantitative correlation analysis indicates that the HC fields are more realistic in the EM analysis than in individual products, especially over the equatorial regions, with signals contributed from all ensemble members. A

  13. From the epipelagic zone to the abyss: Trophic structure at two seamounts in the subtropical and tropical Eastern Atlantic - Part I zooplankton and micronekton

    Science.gov (United States)

    Denda, Anneke; Stefanowitsch, Benjamin; Christiansen, Bernd

    2017-12-01

    Specific mechanisms, driving trophic interactions within the pelagic community may be highly variable in different seamount systems. This study investigated the trophic structure of zooplankton and micronekton above and around Ampère and Senghor, two shallow seamounts in the subtropical and tropical Eastern Atlantic, and over the adjacent abyssal plains. For the identification of food sources and trophic positions stable isotope ratios (δ13C and δ15N) were used. δ13C ranged from -24.7‰ to -15.0‰ and δ15N covered a total range of 0.9-15.9‰. Based on epipelagic particulate organic matter, zooplankton and micronekton usually occupied the 1st-3rd trophic level, including herbivorous, omnivorous and carnivorous taxa. δ13C and δ15N values were generally lower in zooplankton and micronekton of the subtropical waters as compared to the tropical region, due to the differing nutrient availability and phytoplankton communities. Correlations between δ13C and δ15N values of particulate organic matter, zooplankton, micronekton and benthopelagic fishes suggest a linear food chain based on a single energy source from primary production for Ampère Seamount, but no evidence was found for an autochthonus seamount production as compared to the open ocean reference site. Between Senghor Seamount and the open ocean δ13C signatures indicate that hydrodynamic effects at seamounts may modify the energy supply at times, but evidence for a seamount effect on the trophic structure of the pelagic communities was weak, which supports the assumption that seamount communities rely to a large extent on advected food sources.

  14. Dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using WRF-Chem coupled with an AOD data assimilation system

    Directory of Open Access Journals (Sweden)

    D. Chen

    2017-06-01

    Full Text Available This study investigated the dust radiative effects on atmospheric thermodynamics and tropical cyclogenesis over the Atlantic Ocean using the Weather Research and Forecasting Model with Chemistry (WRF-Chem coupled with an aerosol data assimilation (DA system. MODIS AOD (aerosol optical depth data were assimilated with the Gridpoint Statistical Interpolation (GSI three-dimensional variational (3DVAR DA scheme to depict the Saharan dust outbreak events in the 2006 summer. Comparisons with Ozone Monitoring Instrument (OMI, AErosol RObotic NETwork (AERONET, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO observations showed that the system was capable of reproducing the dust distribution. Two sets of 180 h forecasts were conducted with the dust radiative effects activated (RE_ON and inactivated (RE_OFF respectively. Differences between the RE_ON and RE_OFF forecasts showed that low-altitude (high-altitude dust inhibits (favors convection owing to changes in convective inhibition (CIN. Heating in dust layers immediately above the boundary layer increases inhibition, whereas sufficiently elevated heating allows cooling above the boundary layer that reduces convective inhibition. Semi-direct effects in which clouds are altered by thermodynamic changes are also noted, which then alter cloud-radiative temperature (T changes. The analysis of a tropical cyclone (TC suppression case on 5 September shows evidence of enhanced convective inhibition by direct heating in dust, but it also suggests that the low-predictability dynamics of moist convection reduces the determinism of the effects of dust on timescales of TC development (days.

  15. Structure of macroalgal communities on tropical rocky shores inside and outside a marine protected area.

    Science.gov (United States)

    Portugal, Adriana Brizon; Carvalho, Fabrício Lopes; Soares, Marcelo de Oliveira; Horta, Paulo Antunes; de Castro Nunes, José Marcos

    2017-09-01

    The structure of marine macroalgal communities and morpho-functional groups were investigated in a poorly characterized region on the Tropical Southwestern Atlantic coast, Brazil. The survey was conducted at six rocky shores located on the mainland and on coastal islands distributed inside a marine protected area (MPA) and outside the MPA (near a densely populated area). We hypothesized that tropical rocky shores inside the MPA and islands have higher species richness, diversity, and evenness of marine macroalgae. Results confirmed that species richness, diversity and evenness were significantly higher inside the MPA than in rocky shores outside the MPA. Only species richness was higher on islands than on the mainland. The results suggest that human impacts could lead to a competitive advantage and dominance in the articulated calcareous morphotype, resulting in community differences and lower benthic biodiversity in tropical ecosystems near urbanized sites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Reproductive aspects of the caridean shrimp Atya scabra (Leach, 1815 (Decapoda: Atyidae in São Sebastião Island, southwestern Atlantic, Brazil

    Directory of Open Access Journals (Sweden)

    Juliana Herrera-Correal

    2013-09-01

    Full Text Available The caridean freshwater shrimp Atya scabra is a common resident of stream systems of tropical rainforests in America, including Brazilian drainages. This shrimp has an amphidromous life cycle, which increases its vulnerability when facing habitat fragmentation. Since information on the reproduction of this species is still limited, we present here data on egg production, egg loss, and energy investment, to achieve a better understanding of reproductive features of A. scabra. Specimens were collected between 2006 and 2007 in São Sebastião Island, southeastern Brazil, in 13 locations. The fecundity of 21 ovigerous females analyzed ranged between 414 and 19,250 eggs, which were higher than previously reported. However, the larger size of females analyzed may explain the observed intraspecific difference in egg production. During embryogenesis, egg volume and water content increased by 103 and 22.6%, respectively. The initial egg volume of A. scabra in the present study (0.027 mm³ was slightly lower, but comparable to the values reported previously from the same study area. During incubation, females of A. scabra lost 15% of their initially produced eggs. The reproductive output (average RO of 3.6% is the first report for any atyid species. Its value is fairly low compared to other freshwater shrimps, and it is hypothesized that this might be related to a high energy investment in morphological adaptations, which allows the shrimp to cling on to the substrate in the fast flowing environment they inhabit. Additionally, the long life span, a well-known phenomenon in atyid shrimp, may allow the species to invest a relatively low amount of energy per brood in egg production, but over a longer time span.

  17. Climatology of extratropical transition for North Atlantic tropical cyclones in the high-resolution GFDL climate model

    Science.gov (United States)

    Liu, M.; Vecchi, G. A.; Smith, J. A.

    2015-12-01

    The extratropical transition (ET) process of tropical cyclones can lead to fundamental changes in hurricane structure and storms that continue to pose large threats to life and properties. Given the importance of ET, it is necessary to understand how ET changes under a warming climate. Towards this goal, the GFDL climate model (FLOR) is first used to understand the current-day ET climatology. The standard model and a flux-adjusted version of FLOR are both used to examine ET climatology. The operational cyclone phase space method is used to define the onset and completion times of ET. The ET climatology from the climate model is compared with those from two reanalysis data sets ranging from 1979 to 2012. Both models exhibit good skills at simulating the frequency map of phase space diagram. The flux-adjusted version shows much better skill in capturing the ET climatology in terms of ET track patterns, ET locations and monthly ET variations. The model is able to simulate the frequency ratio of reintensified tropical cyclones from all ET cases. Future work involves examining changes in the ET climatology under a changing climate.

  18. Elevated Tropospheric Ozone Over the South Tropical Atlantic in January-February 1999: An Ozone Paradox Due to Interhemispheric Transport, Lightning, or Stratospheric Exchange?

    Science.gov (United States)

    Thompson, Anne M.; Doddridge, Bruce G.; Witte, Jacquelyn C.; Hudson, Robert D.; Luke, Winston T.; Johnson, James E.; Johnson, Bryan J.; Oltmans, Samuel J.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    On this first North American to southern African oceanographic cruise with ozonesonde launches (January and February 1999 on board the NOAA Research Vessel Ronald H Brown between Norfolk, VA, and Cape Town, South Africa) we found: (1) high ozone, CO, and aerosols off northern equatorial Africa from biomass burning, but even higher ozone concentrations off southern Africa which was not burning - an "ozone paradox"; (2) TOMS satellite evidence that south Atlantic elevated ozone in January-February 1999 was a regional feature similar in extent to the well-known September-October ozone maximum. Several mechanisms are considered to explain the "ozone paradox." Convection transporting air from the lower troposphere rich in ozone and/or ozone precursors to the upper troposphere through the ITCZ (intertropical Convergence Zone) may lead to cross-hemisphere transport of pollution. This is supported by trajectory linkage of lower-tropospheric ozone maxima with smoke seen by the TOMS satellite. Lightning-generated NO (nitric oxide) leading to ozone peaks of > 100 ppbv observed at 7-10 km altitude is another explanation. The TRMM (Tropical Rainfall Measuring Mission) Lightning Imaging Sounder shows many lightning flashes over southern Africa, which trajectories link to the high-ozone layers south of the ITCZ. The highest ozone peaks in the middle troposphere correspond to very low water vapor, which may point to photochemical destruction of ozone or subsidence from the upper troposphere which had interacted with stratospheric ozone.

  19. Effect of mulch types on nutrient composition, maize (Zea mays L. yield and soil properties of a tropical Alfisol in Southwestern Nigeria

    Directory of Open Access Journals (Sweden)

    Matthew Awopegba

    2017-04-01

    Full Text Available Field investigations were carried out to evaluate the influence of shrub and herbaceous mulch types on soil properties and nutrient composition of maize (Zea mays L. at the Teaching and Research Farm of the Federal University of Technology, Akure in the rainforest zone of southwestern Nigeria in 2013 and 2014 respectively. The shrub mulch; Gliricidia sepium and Tithonia diversifolia, herbaceous mulch; Calopogonium mucunoides and Moringa oleifera were applied at the rate of 5 t ha-1. Application of NPK (20:10:10 fertilizer at the rate of 200 kg ha-1 was included as the standard treatment for the experiments. The treatments were laid out in randomized complete block design (RCBD with three replication. The growth, agronomic parameters and nutritional quality of maize (Zea mays L. were monitored and determined in both experiments. Results indicated that herbaceous mulch types and NPK fertilizer significantly (P<0.05 increased the number of leaves, plant height and leaf area when compared with the control in both years. Significant increases in yield parameters over the control were obtained for the NPK fertilizer treatment. In 2013 and 2014 cropping season NPK 20-10-10 treatment significantly produced the highest cob yield but was not significantly higher than the yield from Gliricidia sepium treatment in 2014. Soil organic carbon, total nitrogen (N, potassium (K, and exchangeable cations were positively stimulated by herbaceous mulches while residual phosphorus (P was increased by NPK fertilizer treatment. Mulched treatments significantly increased crude protein, carbohydrate, nitrogen, phosphorus and ash content of maize grain in both years of cropping season thereby improving nutritional content of maize grain. Therefore, shrub and herbaceous mulch treatments applied at 5t/ha-1 could be applied alternatively in lieu of scarce and expensive inorganic fertilizer for improved maize yield, soil properties and nutrient composition.

  20. Carbon accumulation rates recorded in the last 150years in tropical high mountain peatlands of the Atlantic Rainforest, SE - Brazil.

    Science.gov (United States)

    Lourençato, Lúcio F; Caldeira, Pedro P; Bernardes, Marcelo C; Buch, Andressa C; Teixeira, Daniel C; Silva-Filho, Emmanoel V

    2017-02-01

    Peatlands are environmental matrices that store large amounts of organic carbon (TOC) and work as records of environmental changes. Recent record of organic carbon accumulated were assessed in two Forest National Parks, Itatiaia and Serra dos Órgãos in the Southeastern of Brazil. Based on organic and inorganic characterization, the cores from peatlands presented a predominance of organic material in an advanced stage of decomposition and those soils were classified as typical Haplosaprists Histosols. The combination of favorable topographic and climatic conditions led to rapid C accumulation across coastal mountain in the tropical peatlands studied, presenting an average accumulation rate of C, in the last century, of 194gCm -2 yr -1 about 7 higher times than the rate found in boreal and subarctic peatlands, those higher values may be related to changes in the hydrological cycle occurred since 1950s. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Comments on "Atlantic Tropical Cyclogenetic Processes during SOP-3 NAMMA in the GEOS-5 Global Data Assimilation and Forecast System"

    Science.gov (United States)

    Braun, Scott A.

    2010-01-01

    Considerable attention has been given to the potential negative impacts of the Saharan air layer (SAL) in recent years. Researchers recently raised questions about the negative impacts of Dunion and Velden and other studies in terms of storms that reached at least tropical storm strength and suggested that the SAL was an intrinsic part of the tropical cyclone environment for both storms that weaken after formation and those that intensify. Braun also suggested that several incorrect assumptions underlie many of the studies on the negative impacts of the SAL, including assumptions that most low-to-midlevel dry tropical air is SAL air, that the SAL is dry throughout its depth, and that the proximity of the SAL to storms struggling to intensify implies some role in that struggle. The recent paper by Reale et al.(RL1) is an example of the problems inherent in some of these assumptions. In their paper, RL1 analyze a simulation from the Global Earth Observing System (GEOS-5) global model and describe an extensive tongue of warm, dry air that stretches southward from at least 30 deg N (the northern limit of their plots) and wraps into a low pressure system during the period 26-29 August 2006, suppressing convection and possibly development of the African easterly wave associated with that low pressure system. They attributed the warm, dry tongue to the SAL (i.e., heating of the air mass during passage over the Sahara and radiative warming of the dust layer). Whether it was their intention, the implication is that this entire feature is due solely to the SAL and not to other possible sources of dry air or warmth. In addition, they suggested that a cool tongue of air in the boundary layer located directly beneath the elevated warm, dry tongue (forming a thermal dipole) was possibly the result of reduced solar radiation caused by an overlying dust layer. They stated that "the cool anomaly in the lower levels does not have any plausible explanation relying only on transport

  2. Atmospheric salt deposition in a tropical mountain rainforest at the eastern Andean slopes of south Ecuador – Pacific or Atlantic origin?

    Directory of Open Access Journals (Sweden)

    S. Makowski Giannoni

    2016-08-01

    Full Text Available Sea salt (NaCl has recently been proven to be of the utmost importance for ecosystem functioning in Amazon lowland forests because of its impact on herbivory, litter decomposition and, thus, carbon cycling. Sea salt deposition should generally decline as distance from its marine source increases. For the Amazon, a negative east–west gradient of sea salt availability is assumed as a consequence of the barrier effect of the Andes Mountains for Pacific air masses. However, this generalized pattern may not hold for the tropical mountain rainforest in the Andes of southern Ecuador. To analyse sea salt availability, we investigated the deposition of sodium (Na+ and chloride (Cl−, which are good proxies of sea spray aerosol. Because of the complexity of the terrain and related cloud and rain formation processes, sea salt deposition was analysed from both, rain and occult precipitation (OP along an altitudinal gradient over a period between 2004 and 2009. To assess the influence of easterly and westerly air masses on the deposition of sodium and chloride over southern Ecuador, sea salt aerosol concentration data from the Monitoring Atmospheric Composition and Climate (MACC reanalysis data set and back-trajectory statistical methods were combined. Our results, based on deposition time series, show a clear difference in the temporal variation of sodium and chloride concentration and Na+ ∕ Cl− ratio in relation to height and exposure to winds. At higher elevations, sodium and chloride present a higher seasonality and the Na+ ∕ Cl− ratio is closer to that of sea salt. Medium- to long-range sea salt transport exhibited a similar seasonality, which shows the link between our measurements at high elevations and the sea salt synoptic transport. Although the influence of the easterlies was predominant regarding the atmospheric circulation, the statistical analysis of trajectories and hybrid receptor models revealed a stronger impact of the

  3. A synthesis of the environmental response of the North and South Atlantic Sub-Tropical Gyres during two decades of AMT

    Science.gov (United States)

    Aiken, Jim; Brewin, Robert J. W.; Dufois, Francois; Polimene, Luca; Hardman-Mountford, Nick J.; Jackson, Thomas; Loveday, Ben; Hoya, Silvana Mallor; Dall'Olmo, Giorgio; Stephens, John; Hirata, Takafumi

    2017-11-01

    Anthropogenically-induced global warming is expected to decrease primary productivity in the subtropical oceans by strengthening stratification of the water column and reducing the flux of nutrients from deep-waters to the sunlit surface layers. Identification of such changes is hindered by a paucity of long-term, spatially-resolved, biological time-series data at the basin scale. This paper exploits Atlantic Meridional Transect (AMT) data on physical and biogeochemical properties (1995-2014) in synergy with a wide range of remote-sensing (RS) observations from ocean colour, Sea Surface Temperature (SST), Sea Surface Salinity (SSS) and altimetry (surface currents), combined with different modelling approaches (both empirical and a coupled 1-D Ecosystem model), to produce a synthesis of the seasonal functioning of the North and South Atlantic Sub-Tropical Gyres (STGs), and assess their response to longer-term changes in climate. We explore definitive characteristics of the STGs using data of physical (SST, SSS and peripheral current systems) and biogeochemical variables (chlorophyll and nitrate), with inherent criteria (permanent thermal stratification and oligotrophy), and define the gyre boundary from a sharp gradient in these physical and biogeochemical properties. From RS data, the seasonal cycles for the period 1998-2012 show significant relationships between physical properties (SST and PAR) and gyre area. In contrast to expectations, the surface layer chlorophyll concentration from RS data (CHL) shows an upward trend for the mean values in both subtropical gyres. Furthermore, trends in physical properties (SST, PAR, gyre area) differ between the North and South STGs, suggesting the processes responsible for an upward trend in CHL may vary between gyres. There are significant anomalies in CHL and SST that are associated with El Niño events. These conclusions are drawn cautiously considering the short length of the time-series (1998-2012), emphasising the need

  4. A model study of the seasonality of sea surface temperature and circulation in the Atlantic North-Eastern Tropical Upwelling System.

    Directory of Open Access Journals (Sweden)

    Saliou eFaye

    2015-09-01

    Full Text Available The climatological seasonal cycle of the sea surface temperature (SST in the north-eastern tropical Atlantic (7-25°N, 26-12°W is studied using a mixed layer heat budget in a regional ocean general circulation model. The region, which experiences one of the larger SST cycle in the tropics, forms the main part of the Guinea Gyre. It is characterized by a seasonally varying open ocean and coastal upwelling system, driven by the movements of the intertropical convergence zone (ITCZ. The model annual mean heat budget has two regimes schematically. South of roughly 12°N, advection of equatorial waters, mostly warm, and warming by vertical mixing, is balanced by net air-sea flux. In the rest of the domain, a cooling by vertical mixing, reinforced by advection at the coast, is balanced by the air-sea fluxes. Regarding the seasonal cycle, within a narrow continental band, in zonal mean, the SST early decrease (from September, depending on latitude, until December is driven by upwelling dynamics off Senegal and Mauritania (15°-20°N, and instead by air-sea fluxes north and south of these latitudes. Paradoxically, the later peaks of upwelling intensity (from March to July, with increasing latitude essentially damp the warming phase, driven by air-sea fluxes. The open ocean cycle to the west, is entirely driven by the seasonal net air-sea fluxes. The oceanic processes significantly oppose it, but for winter north of ~18°N. Vertical mixing in summer-autumn tends to cool (warm the surface north (south of the ITCZ, and advective cooling or warming by the geostrophic Guinea Gyre currents and the Ekman drift. This analysis supports previous findings on the importance of air-sea fluxes offshore. It mainly offers quantitative elements on the modulation of the SST seasonal cycle by the ocean circulation, and particularly by the upwelling dynamics.Keywords: SST, upwelling, circulation, heat budget, observations, modeling

  5. From the epipelagic zone to the abyss: Trophic structure at two seamounts in the subtropical and tropical Eastern Atlantic - Part II Benthopelagic fishes

    Science.gov (United States)

    Denda, Anneke; Stefanowitsch, Benjamin; Christiansen, Bernd

    2017-12-01

    Specific mechanisms, driving trophic interactions between seamount associated fishes and the pelagic community may be highly variable in different seamount systems. This study investigated the trophic structure and the main prey of benthopelagic fishes from the summit and slope regions of Ampère and Senghor, two shallow seamounts in the subtropical and tropical NE Atlantic, and the adjacent deep-sea plains. For the identification of food sources and nutritional links to the pelagic realm a combination of stomach content and stable isotope ratio (δ13C and δ15N) analyses was used. δ13C ranged from -22.2‰ to -15.4‰ and δ15N covered a total range of 8.0-15.9‰. Feeding types of fish species comprised mainly zooplanktivores and mixed feeders, but also benthivores, piscivores, and predator-scavengers. Based on epipelagic particulate organic matter, they occupied trophic positions between the 2nd and 4th trophic level. Differences in stomach contents and stable isotope signatures indicate a resource partitioning among the benthopelagic fish fauna through distinct habitat choice, vertical feeding positions and prey selection. Topographic trapping of vertically migrating zooplankton on the summit seemed to be of minor importance for food supply of the resident near-bottom fishes, rather horizontal current-driven advection of the planktonic prey was assumed as major factor. Vertically migrating micronekton and mesopelagic fishes show up as key players within the food webs at Ampère and Senghor Seamounts and the adjacent deep-sea plains.

  6. Model simulation of changes in N2O and NO emissions with conversion of tropical rain forests to pastures in the Costa Rican Atlantic Zone

    Science.gov (United States)

    Liu, Shuguang; Reiners, William A.; Keller, Michael; Schimel, David S.

    1999-06-01

    Nitrous oxide (N2O) and nitric oxide (NO) are among the trace gases of concern because of their importance in global climate and atmospheric chemistry. Modeling techniques are needed for simulating the spatial and temporal dynamics of N2O and NO emissions from soils into the atmosphere. In this study, we modified the ecosystem model CENTURY to simulate changes in N2O and NO soil emissions through the process of converting tropical moist forests to pastures in the Atlantic Lowlands of Costa Rica. Measurements of water-filled pore space (WFPS) and fluxes of N2O and NO from a chronosequence of pastures were used for calibration and testing of the model. It was found that the N2O+NO — WFPS and N2O:NO — WFPS relationships as developed from primary forests could be generalized to the chronosequence of pastures and other land use systems in the region. Modeled net increases (compared to primary forests) in total N2O and NO production after conversion from forest to pasture were 514 kg N ha-1 during the first 15 years under normal field conditions. The nitrogen loss in the form of N2O and NO during the first 15 years could range from 401 to 548 kg N ha-1, depending on the amounts of forest residue remaining on pasture sites. N2O-N accounted for 90% of the gas fluxes, while NO-N accounted for 10%. Sensitivity analysis indicated that the impacts of forest-pasture conversion on N2O and NO emissions from soil into the atmosphere were complex, depending on the initial conditions of the forest-derived pastures, management practices, soil physical and chemical conditions and their changes over time, N availability, and climate. It is therefore important to incorporate the spatial and temporal heterogeneities of those controlling factors in estimating regional and global N2O and NO emissions from soils into the atmosphere.

  7. Chemistry, transport and dry deposition of trace gases in the boundary layer over the tropical Atlantic Ocean and the Guyanas during the GABRIEL field campaign

    Directory of Open Access Journals (Sweden)

    A. Stickler

    2007-07-01

    Full Text Available We present a comparison of different Lagrangian and chemical box model calculations with measurement data obtained during the GABRIEL campaign over the tropical Atlantic Ocean and the Amazon rainforest in the Guyanas, October 2005. Lagrangian modelling of boundary layer (BL air constrained by measurements is used to derive a horizontal gradient (≈5.6 pmol/mol km−1 of CO from the ocean to the rainforest (east to west. This is significantly smaller than that derived from the measurements (16–48 pmol/mol km−1, indicating that photochemical production from organic precursors alone cannot explain the observed strong gradient. It appears that HCHO is overestimated by the Lagrangian and chemical box models, which include dry deposition but not exchange with the free troposphere (FT. The relatively short lifetime of HCHO implies substantial BL-FT exchange. The mixing-in of FT air affected by African and South American biomass burning at an estimated rate of 0.12 h−1 increases the CO and decreases the HCHO mixing ratios, improving agreement with measurements. A mean deposition velocity of 1.35 cm/s for H2O2 over the ocean as well as over the rainforest is deduced assuming BL-FT exchange adequate to the results for CO. The measured increase of the organic peroxides from the ocean to the rainforest (≈0.66 nmol/mol d−1 is significantly overestimated by the Lagrangian model, even when using high values for the deposition velocity and the entrainment rate. Our results point at either heterogeneous loss of organic peroxides and/or their radical precursors, underestimated photodissociation or missing reaction paths of peroxy radicals not forming peroxides in isoprene chemistry. We calculate a mean integrated daytime net ozone production (NOP in the BL of (0.2±5.9 nmol/mol (ocean and (2.4±2.1 nmol/mol (rainforest. The NOP strongly correlates with NO and has a positive tendency in

  8. Production, partitioning and stoichiometry of organic matter under variable nutrient supply during mesocosm experiments in the tropical Pacific and Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    J. M. S. Franz

    2012-11-01

    Full Text Available Oxygen-deficient waters in the ocean, generally referred to as oxygen minimum zones (OMZ, are expected to expand as a consequence of global climate change. Poor oxygenation is promoting microbial loss of inorganic nitrogen (N and increasing release of sediment-bound phosphate (P into the water column. These intermediate water masses, nutrient-loaded but with an N deficit relative to the canonical N:P Redfield ratio of 16:1, are transported via coastal upwelling into the euphotic zone. To test the impact of nutrient supply and nutrient stoichiometry on production, partitioning and elemental composition of dissolved (DOC, DON, DOP and particulate (POC, PON, POP organic matter, three nutrient enrichment experiments were conducted with natural microbial communities in shipboard mesocosms, during research cruises in the tropical waters of the southeast Pacific and the northeast Atlantic. Maximum accumulation of POC and PON was observed under high N supply conditions, indicating that primary production was controlled by N availability. The stoichiometry of microbial biomass was unaffected by nutrient N:P supply during exponential growth under nutrient saturation, while it was highly variable under conditions of nutrient limitation and closely correlated to the N:P supply ratio, although PON:POP of accumulated biomass generally exceeded the supply ratio. Microbial N:P composition was constrained by a general lower limit of 5:1. Channelling of assimilated P into DOP appears to be the mechanism responsible for the consistent offset of cellular stoichiometry relative to inorganic nutrient supply and nutrient drawdown, as DOP build-up was observed to intensify under decreasing N:P supply. Low nutrient N:P conditions in coastal upwelling areas overlying O2-deficient waters seem to represent a net source for DOP, which may stimulate growth of diazotrophic phytoplankton. These results demonstrate that microbial nutrient assimilation and

  9. Piecewise Structural Equation Model (SEM) Disentangles the Environmental Conditions Favoring Diatom Diazotroph Associations (DDAs) in the Western Tropical North Atlantic (WTNA).

    Science.gov (United States)

    Stenegren, Marcus; Berg, Carlo; Padilla, Cory C; David, Stefan-Sebastian; Montoya, Joseph P; Yager, Patricia L; Foster, Rachel A

    2017-01-01

    Diatom diazotroph associations (DDAs) are important components in the world's oceans, especially in the western tropical north Atlantic (WTNA), where blooms have a significant impact on carbon and nitrogen cycling. However, drivers of their abundances and distribution patterns remain unknown. Here, we examined abundance and distribution patterns for two DDA populations in relation to the Amazon River (AR) plume in the WTNA. Quantitative PCR assays, targeting two DDAs (het-1 and het-2) by their symbiont's nifH gene, served as input in a piecewise structural equation model (SEM). Collections were made during high (spring 2010) and low (fall 2011) flow discharges of the AR. The distributions of dissolved nutrients, chlorophyll- a , and DDAs showed coherent patterns indicative of areas influenced by the AR. A symbiotic Hemiaulus hauckii-Richelia (het-2) bloom (>10 6 cells L -1 ) occurred during higher discharge of the AR and was coincident with mesohaline to oceanic (30-35) sea surface salinities (SSS), and regions devoid of dissolved inorganic nitrogen (DIN), low concentrations of both DIP (>0.1 μmol L -1 ) and Si (>1.0 μmol L -1 ). The Richelia (het-1) associated with Rhizosolenia was only present in 2010 and at lower densities (10-1.76 × 10 5 nifH copies L -1 ) than het-2 and limited to regions of oceanic SSS (>36). The het-2 symbiont detected in 2011 was associated with H. membranaceus (>10 3 nifH copies L -1 ) and were restricted to regions with mesohaline SSS (31.8-34.3), immeasurable DIN, moderate DIP (0.1-0.60 μmol L -1 ) and higher Si (4.19-22.1 μmol L -1 ). The piecewise SEM identified a profound direct negative effect of turbidity on the het-2 abundance in spring 2010, while DIP and water turbidity had a more positive influence in fall 2011, corroborating our observations of DDAs at subsurface maximas. We also found a striking difference in the influence of salinity on DDA symbionts suggesting a niche differentiation and preferences in oceanic and

  10. Herpetological surveys of south-western and south-eastern regions ...

    African Journals Online (AJOL)

    The herpetofauna of part of the south-western (Lagos, Ogun and Oyo States) and south-eastern (Cross River State) regions were investigated. Specimens were located opportunistically during visual surveys. Both regions fall in the tropical zone, and the south-western region surveyed, was mostly lowland, degraded forests ...

  11. GHRSST Level 2P Regional Subskin Sea Surface Temperature from the Tropical Rainfall Mapping Mission (TRMM) Microwave Imager (TMI) for the Atlantic Ocean (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) is a well calibrated passive microwave radiometer, similar to SSM/I, that contains lower...

  12. Heavy Rainfall Episodes in the Eastern Northeast Brazil Linked to Large-Scale Ocean-Atmosphere Conditions in the Tropical Atlantic

    Directory of Open Access Journals (Sweden)

    Yves K. Kouadio

    2012-01-01

    Full Text Available Relationships between simultaneous occurrences of distinctive atmospheric easterly wave (EW signatures that cross the south-equatorial Atlantic, intense mesoscale convective systems (lifespan > 2 hour that propagate westward over the western south-equatorial Atlantic, and subsequent strong rainfall episodes (anomaly > 10 mm·day−1 that occur in eastern Northeast Brazil (ENEB are investigated. Using a simple diagnostic analysis, twelve cases with EW lifespan ranging between 3 and 8 days and a mean velocity of 8 m·s−1 were selected and documented during each rainy season of 2004, 2005, and 2006. These cases, which represent 50% of the total number of strong rainfall episodes and 60% of the rainfall amount over the ENEB, were concomitant with an acceleration of the trade winds over the south-equatorial Atlantic, an excess of moisture transported westward from Africa to America, and a strengthening of the convective activity in the oceanic region close to Brazil. Most of these episodes occurred during positive sea surface temperature anomaly patterns over the entire south-equatorial Atlantic and low-frequency warm conditions within the oceanic mixing layer. A real-time monitoring and the simulation of this ocean-atmosphere relationship could help in forecasting such dramatic rainfall events.

  13. Hydrological structure and biological productivity of the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, U.D.; Muraleedharan, P.M.

    Hydrological structure analyses of regions in the tropical Atlantic Ocean have consistently revealed the existence of a typical tropical structure characterized by a nitrate-depleted mixed layer above the thermocline. The important biological...

  14. Temperature fluctuations in the Atlantic Ocean

    International Nuclear Information System (INIS)

    Hjoello, Solfrid Saetre

    2005-01-01

    The article discusses the temperature fluctuations in connection with drought in Africa, the climate in North America, the European heat waves and the frequent tropical hurricanes in the Atlantic Ocean. Problems with climate modelling and some pollution aspects are mentioned

  15. Environmental Management Audit: Southwestern Power Administration (Southwestern)

    International Nuclear Information System (INIS)

    1993-03-01

    This report documents the results of the Environmental Management Audit completed for the Southwestern Power Administration. During this Audit, activities and records were reviewed and personnel interviewed. The onsite portion of the Southwestern Audit was conducted from November 30 through December 11, 1992, by the US Department of Energy's Office of Environmental Audit (EH-24). EH-24 carries out independent assessments of Department of Energy (DOE) facilities and activities as part of the Assistant Secretary's Environmental Audit Program. This program is designed to evaluate the status of DOE facilities/activities regarding compliance with laws, regulations, DOE Orders, formal written procedures, compliance agreements, and Best Management Practices (BMPs). This internal oversight function plays an important role in improving the compliance status of DOE operations. The Environmental Management Audit stresses DOE's policy that it is the responsibility of line management to conduct operations in an environmentally sound and safe manner. The Environmental Management Audit focuses on management systems and programs, whereas the Environmental Baseline Audit conducted in March 1991 focused on specific compliance issues. The scope of the Southwestern Environmental Management Audit included a review of all systems and functions necessary for effective environmental management. Specific areas of review included: Organizational Structure; Environmental Commitment; Environmental Protection Programs; Formality of Environmental Programs; Internal and External Communication; Staff Resources, Training, and Development; and Program Evaluation, Reporting, and Corrective Action

  16. Divergent responses of tropical cyclone genesis factors to strong volcanic eruptions at different latitudes

    Science.gov (United States)

    Yan, Qing; Zhang, Zhongshi; Wang, Huijun

    2018-03-01

    To understand the behaviors of tropical cyclones (TCs), it is very important to explore how TCs respond to anthropogenic greenhouse gases and natural forcings. Volcanic eruptions are a major natural forcing mechanism because they inject sulphate aerosols into the stratosphere, which modulate the global climate by absorbing and scattering solar radiation. The number of Atlantic hurricanes is thought to be reduced following strong tropical eruptions, but whether the response of TCs varies with the locations of the volcanoes and the different ocean basins remains unknown. Here, we use the Community Earth System Model-Last Millennium Ensemble to investigate the response of the large-scale environmental factors that spawn TCs to strong volcanic eruptions at different latitudes. A composite analysis indicates that tropical and northern hemisphere volcanic eruptions lead to significantly unfavorable conditions for TC genesis over the whole Pacific basin and the North Atlantic during the 3 years post-eruption, relative to the preceding 3 years. Southern hemisphere volcanic eruptions result in obviously unfavorable conditions for TC formation over the southwestern Pacific, but more favorable conditions over the North Atlantic. The mean response over the Indian Ocean is generally muted and insignificant. It should be noted that volcanic eruptions impact on environmental conditions through both the direct effect (i.e. on radiative forcing) and the indirect effect (i.e. on El Niño-Southern Oscillation), which is not differentiated in this study. In addition, the spread of the TC genesis response is considerably large for each category of eruptions over each ocean basin, which is also seen in the observational/proxy-based records. This large spread is attributed to the differences in stratospheric aerosol distributions, initial states and eruption intensities, and makes the short-term forecast of TC activity following the next large eruption challenging.

  17. Tropical radioecology tropical radioecology

    CERN Document Server

    Baxter, M

    2012-01-01

    Tropical Radioecology is a guide to the wide range of scientific practices and principles of this multidisciplinary field. It brings together past and present studies in the tropical and sub-tropical areas of the planet, highlighting the unique aspects of tropical systems. Until recently, radioecological models for tropical environments have depended upon data derived from temperate environments, despite the differences of these regions in terms of biota and abiotic conditions. Since radioactivity can be used to trace environmental processes in humans and other biota, this book offers examples of studies in which radiotracers have been used to assess biokinetics in tropical biota. Features chapters, co-authored by world experts, that explain the origins, inputs, distribution, behaviour, and consequences of radioactivity in tropical and subtropical systems. Provides comprehensive lists of relevant data and identifies current knowledge gaps to allow for targeted radioecological research in the future. Integrate...

  18. Atlantic Region

    NARCIS (Netherlands)

    Elands, B.H.M.; Bell, S.; Blok, J.

    2010-01-01

    Chapter 2 explores recreation and tourism practices in forest areas in the Atlantic region, which refers to the geographical area close to the North Sea and the Atlantic Ocean. The Atlantic countries described in this section are Belgium (Flanders and Wallonia), Denmark, Iceland, Ireland, the

  19. Description of a new species of skate of the genus Malacoraja Stehmann, 1970: the first species from the southwestern Atlantic Ocean, with notes on generic monophyly and composition (Chondrichthyes: Rajidae

    Directory of Open Access Journals (Sweden)

    Marcelo R. de Carvalho

    Full Text Available The first report of a western South Atlantic soft skate, genus Malacoraja Stehmann, 1970, is described as Malacoraja obscura, new species, from the southeastern Brazilian continental slope off the states of Espírito Santo and Rio de Janeiro, in depths ranging from 808-1105 m. The new species is known from five specimens and is distinguished from congeners by its unique dorsal coloration with small, faded white spots on disc and pelvic fins, by retaining in larger specimens an irregular row of thorns along dorsal midline of tail (extending from tail base to two-thirds of tail length in 680 mm total length female, and by presenting a ventral tail midline devoid of small denticles only at base (naked region not extending posterior to pelvic fin rear margin. Further diagnostic characters in combination include the lack of scapular thorns in larger specimens, elevated number of tooth rows (64/62 tooth rows in subadult male of 505 mm TL, and 76/74 in large female of 680 mm TL and vertebrae (27-28 Vtr, 68-75 Vprd, ventral disc and tail with a uniform dark brown coloration, paired postventral fenestrae on scapulocoracoid, enlarged posterior postventral fenestra, circular foramen magnum and paired internal carotid foramina on braincase floor. Adult males were unavailable for study, but an anatomical description of M. obscura, n. sp., is provided. Comparisons are made with all known material of M. kreffti, literature accounts of M. senta, and with abundant material of South African M. spinacidermis; M. obscura, n. sp., most closely resembles M. spinacidermis from the eastern South Atlantic in squamation, coloration and size. Malacoraja is monophyletic due to its unique squamation and rostral appendices, and apparently comprises two species-groups, one for M. obscura and M. spinacidermis, and the other for M. kreffti and M. senta, but clarification of species-level relationships must await more anatomical information, particularly of the latter two

  20. Southwestern Grassland Ecology

    Science.gov (United States)

    Paulette L. Ford; Deborah U. Potter; Rosemary Pendleton; Burton Pendleton; Wayne A. Robbie; Gerald J. Gottfried

    2004-01-01

    This chapter provides a brief overview, and selected in-depth coverage, of the factors and processes that have formed, and continue to shape, our Southwestern grasslands. In general, this chapter looks at how distributions of grasslands are regulated by soils and climate, and modified by disturbance (natural and/or anthropogenic). The attendant ecological components of...

  1. The effects of Hurricane Irene and Tropical Storm Lee on the bed sediment geochemistry of U.S. Atlantic coastal rivers

    Science.gov (United States)

    Horowitz, Arthur J.

    2013-01-01

    Hurricane Irene and Tropical Storm Lee, both of which made landfall in the U.S. between late August and early September 2011, generated record or near record water discharges in 41 coastal rivers between the North Carolina/South Carolina border and the U.S./Canadian border. Despite the discharge of substantial amounts of suspended sediment from many of these rivers, as well as the probable influx of substantial amounts of eroded material from the surrounding basins, the geochemical effects on the wastewater/solid sludge. The limited number of significant sediment-associated chemical changes that were detected probably resulted from two potential processes: (1) the flushing of in-stream land-use affected sediments that were replaced by baseline material more representative of local geology and/or soils (declining concentrations), and/or (2) the inclusion of more heavily affected material as a result of urban nonpoint-source runoff and/or releases from flooded treatment facilities (increasing concentrations). Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  2. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T

    2006-01-01

    ... of tropical cyclones The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved...

  3. Osteología craneal comparada de tres especies de lenguado del género Paralichthys (Pleuronectiformes, Paralichthyidae del Atlántico suroccidental Comparative cranial osteology of three species of the flatfish genus Paralichthys (Pleuronectiformes, Paralichthyidae from the southwestern Atlantic

    Directory of Open Access Journals (Sweden)

    JUAN M. DÍAZ DE ASTARLOA

    2005-09-01

    Full Text Available Se realiza un análisis osteológico comparativo del esqueleto craneal en Paralichthys isosceles, P. orbignyanus y P. patagonicus, tres especies de lenguados presentes en el Atlántico suroccidental. Se describen las características de los componentes óseos y se detallan las diferencias morfológicas y morfométricas encontradas, con el fin de aportar elementos diagnósticos para la identificación taxonómica de las tres especies de Paralichthys. Se utilizaron técnicas de desarticulación de esqueletos, tanto en ejemplares frescos congelados, como en especímenes conservados en líquidos fijadores. También fueron usadas técnicas de clareado y tinción diferencial para ejemplares de pequeño tamaño. Se observaron potenciales características diagnósticas para la discriminación de las especies en los huesos paretmoides derecho, lacrimal izquierdo, anguloarticular, mesopterigoides, los otolitos y el número de dientes del dentario. Se discuten las relaciones entre los huesos y se comparan sus características con las halladas en otras especies del género Paralichthys, en particular, y en otros Pleuronectiformes en generalAn osteological analysis of the cranial skeleton of the southwestern Atlantic flatfish species Paralichthys isosceles, P. orbignyanus and P. patagonicus was carried out based on comparative morphology and morphometrics of the bones. The objective was to provide osteological evidence of diagnostic value for a correct identification of the flatfish species. Methods for preparing disarticulated skeletons were used for both dissected fresh-frosen and alcohol-preserved specimens. Also methods of clearing and staining for bone and cartilage were applied for small fish specimens. Potentially diagnostic features were found to distinguish among species in the right parethmoid, left lachrymal, angulo-articular, mesopterygoid, the otoliths, and the number of dentary teeth. Relationships between bones are discussed and bone

  4. Independent origins of cultivated coconut (Cocos nucifera L. in the old world tropics.

    Directory of Open Access Journals (Sweden)

    Bee F Gunn

    Full Text Available As a portable source of food, water, fuel, and construction materials, the coconut (Cocos nucifera L. played a fundamental role in human migrations and the development of civilization across the humid tropics. Here we investigated the coconut's domestication history and its population genetic structure as it relates to human dispersal patterns. A sample of 1,322 coconut accessions, representing the geographical and phenotypic diversity of the species, was examined using ten microsatellite loci. Bayesian analyses reveal two highly genetically differentiated subpopulations that correspond to the Pacific and Indo-Atlantic oceanic basins. This pattern suggests independent origins of coconut cultivation in these two world regions, with persistent population structure on a global scale despite long-term human cultivation and dispersal. Pacific coconuts show additional genetic substructure corresponding to phenotypic and geographical subgroups; moreover, the traits that are most clearly associated with selection under human cultivation (dwarf habit, self-pollination, and "niu vai" fruit morphology arose only in the Pacific. Coconuts that show evidence of genetic admixture between the Pacific and Indo-Atlantic groups occur primarily in the southwestern Indian Ocean. This pattern is consistent with human introductions of Pacific coconuts along the ancient Austronesian trade route connecting Madagascar to Southeast Asia. Admixture in coastal east Africa may also reflect later historic Arab trading along the Indian Ocean coastline. We propose two geographical origins of coconut cultivation: island Southeast Asia and southern margins of the Indian subcontinent.

  5. Independent origins of cultivated coconut (Cocos nucifera L.) in the old world tropics.

    Science.gov (United States)

    Gunn, Bee F; Baudouin, Luc; Olsen, Kenneth M

    2011-01-01

    As a portable source of food, water, fuel, and construction materials, the coconut (Cocos nucifera L.) played a fundamental role in human migrations and the development of civilization across the humid tropics. Here we investigated the coconut's domestication history and its population genetic structure as it relates to human dispersal patterns. A sample of 1,322 coconut accessions, representing the geographical and phenotypic diversity of the species, was examined using ten microsatellite loci. Bayesian analyses reveal two highly genetically differentiated subpopulations that correspond to the Pacific and Indo-Atlantic oceanic basins. This pattern suggests independent origins of coconut cultivation in these two world regions, with persistent population structure on a global scale despite long-term human cultivation and dispersal. Pacific coconuts show additional genetic substructure corresponding to phenotypic and geographical subgroups; moreover, the traits that are most clearly associated with selection under human cultivation (dwarf habit, self-pollination, and "niu vai" fruit morphology) arose only in the Pacific. Coconuts that show evidence of genetic admixture between the Pacific and Indo-Atlantic groups occur primarily in the southwestern Indian Ocean. This pattern is consistent with human introductions of Pacific coconuts along the ancient Austronesian trade route connecting Madagascar to Southeast Asia. Admixture in coastal east Africa may also reflect later historic Arab trading along the Indian Ocean coastline. We propose two geographical origins of coconut cultivation: island Southeast Asia and southern margins of the Indian subcontinent.

  6. Population structure of humpback whales from their breeding grounds in the South Atlantic and Indian Oceans.

    Science.gov (United States)

    Rosenbaum, Howard C; Pomilla, Cristina; Mendez, Martin; Leslie, Matthew S; Best, Peter B; Findlay, Ken P; Minton, Gianna; Ersts, Peter J; Collins, Timothy; Engel, Marcia H; Bonatto, Sandro L; Kotze, Deon P G H; Meÿer, Mike; Barendse, Jaco; Thornton, Meredith; Razafindrakoto, Yvette; Ngouessono, Solange; Vely, Michel; Kiszka, Jeremy

    2009-10-08

    Although humpback whales are among the best-studied of the large whales, population boundaries in the Southern Hemisphere (SH) have remained largely untested. We assess population structure of SH humpback whales using 1,527 samples collected from whales at fourteen sampling sites within the Southwestern and Southeastern Atlantic, the Southwestern Indian Ocean, and Northern Indian Ocean (Breeding Stocks A, B, C and X, respectively). Evaluation of mtDNA population structure and migration rates was carried out under different statistical frameworks. Using all genetic evidence, the results suggest significant degrees of population structure between all ocean basins, with the Southwestern and Northern Indian Ocean most differentiated from each other. Effective migration rates were highest between the Southeastern Atlantic and the Southwestern Indian Ocean, followed by rates within the Southeastern Atlantic, and the lowest between the Southwestern and Northern Indian Ocean. At finer scales, very low gene flow was detected between the two neighbouring sub-regions in the Southeastern Atlantic, compared to high gene flow for whales within the Southwestern Indian Ocean. Our genetic results support the current management designations proposed by the International Whaling Commission of Breeding Stocks A, B, C, and X as four strongly structured populations. The population structure patterns found in this study are likely to have been influenced by a combination of long-term maternally directed fidelity of migratory destinations, along with other ecological and oceanographic features in the region.

  7. Population structure of humpback whales from their breeding grounds in the South Atlantic and Indian Oceans.

    Directory of Open Access Journals (Sweden)

    Howard C Rosenbaum

    2009-10-01

    Full Text Available Although humpback whales are among the best-studied of the large whales, population boundaries in the Southern Hemisphere (SH have remained largely untested. We assess population structure of SH humpback whales using 1,527 samples collected from whales at fourteen sampling sites within the Southwestern and Southeastern Atlantic, the Southwestern Indian Ocean, and Northern Indian Ocean (Breeding Stocks A, B, C and X, respectively. Evaluation of mtDNA population structure and migration rates was carried out under different statistical frameworks. Using all genetic evidence, the results suggest significant degrees of population structure between all ocean basins, with the Southwestern and Northern Indian Ocean most differentiated from each other. Effective migration rates were highest between the Southeastern Atlantic and the Southwestern Indian Ocean, followed by rates within the Southeastern Atlantic, and the lowest between the Southwestern and Northern Indian Ocean. At finer scales, very low gene flow was detected between the two neighbouring sub-regions in the Southeastern Atlantic, compared to high gene flow for whales within the Southwestern Indian Ocean. Our genetic results support the current management designations proposed by the International Whaling Commission of Breeding Stocks A, B, C, and X as four strongly structured populations. The population structure patterns found in this study are likely to have been influenced by a combination of long-term maternally directed fidelity of migratory destinations, along with other ecological and oceanographic features in the region.

  8. Economically important species dominate aboveground carbon storage in forests of southwestern Amazonia

    NARCIS (Netherlands)

    Galia Selaya, N.; Zuidema, Pieter A.; Baraloto, Christopher; Vos, Vincent A.; Brienen, Roel J.W.; Pitman, Nigel C.A.; Brown, Foster Irving; Duchelle, Amy E.; Araujo-Murakami, Alejandro; Oliveiracarillo, Luis A.; Vasquez Colomo, Guido H.; Chupinagua, Severo Meo; Nay, Hugo Fuentes; Perz, Stephen

    2017-01-01

    Tree species in tropical forests provide economically important goods and ecosystem services. In submontane forests of southwestern Amazonia, we investigated the degree to which tree species important for subsistence and trade contribute to aboveground carbon storage (AGC). We used 41 1-hectare

  9. Tropical Rainforests.

    Science.gov (United States)

    Nigh, Ronald B.; Nations, James D.

    1980-01-01

    Presented is a summary of scientific knowledge about the rainforest environment, a tropical ecosystem in danger of extermination. Topics include the current state of tropical rainforests, the causes of rainforest destruction, and alternatives of rainforest destruction. (BT)

  10. An Atlantic influence on Amazon rainfall

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jin-Ho [University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD (United States); Zeng, Ning [University of Maryland, Earth System Science Interdisciplinary Center, College Park, MD (United States); University of Maryland, Department of Atmospheric and Oceanic Science, College Park, MD (United States)

    2010-02-15

    Rainfall variability over the Amazon basin has often been linked to variations in Pacific sea surface temperature (SST), and in particular, to the El Nino/Southern Oscillation (ENSO). However, only a fraction of Amazon rainfall variability can be explained by ENSO. Building upon the recent work of Zeng (Environ Res Lett 3:014002, 2008), here we provide further evidence for an influence on Amazon rainfall from the tropical Atlantic Ocean. The strength of the North Atlantic influence is found to be comparable to the better-known Pacific ENSO connection. The tropical South Atlantic Ocean also shows some influence during the wet-to-dry season transition period. The Atlantic influence is through changes in the north-south divergent circulation and the movement of the ITCZ following warm SST. Therefore, it is strongest in the southern part of the Amazon basin during the Amazon's dry season (July-October). In contrast, the ENSO related teleconnection is through anomalous east-west Walker circulation with largely concentrated in the eastern (lower) Amazon. This ENSO connection is seasonally locked to boreal winter. A complication due to the influence of ENSO on Atlantic SST causes an apparent North Atlantic SST lag of Amazon rainfall. Removing ENSO from North Atlantic SST via linear regression resolves this causality problem in that the residual Atlantic variability correlates well and is in phase with the Amazon rainfall. A strong Atlantic influence during boreal summer and autumn is particularly significant in terms of the impact on the hydro-ecosystem which is most vulnerable during the dry season, as highlighted by the severe 2005 Amazon drought. Such findings have implications for both seasonal-interannual climate prediction and understanding the longer-term changes of the Amazon rainforest. (orig.)

  11. Temperature profile from NOAA Ship RESEARCHER and other platforms as part of the ARP (Global Atmospheric Research Program) Atlantic Tropical Experiment from 1974-08-28 to 1974-09-20 (NODC Accession 7800314)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected using BT and XBT from NOAA Ship RESEARCHER and other platforms in the TOGA area - Atlantic from 28 August 1974 to 20...

  12. Saharan Dust as a Causal Factor of Significant Cloud Cover Along the Saharan Air Layer in the Atlantic Ocean

    Science.gov (United States)

    Kishcha, Pavel; Da Silva, Arlindo M.; Starobinet, Boris; Alpert, Pinhas

    2016-01-01

    The tropical Atlantic is frequently affected by Saharan dust intrusions. Based on MODIS cloud fraction (CF) data during the ten-year study period, we found that these dust intrusions contribute to significant cloud cover along the Saharan Air Layer (SAL). Below the temperature inversion at the SAL's base, the presence of large amounts of settling dust particles, together with marine aerosols, produces meteorological conditions suitable for the formation of shallow stratocumulus clouds. The significant cloud fraction along the SAL together with clouds over the Atlantic Inter-tropical Convergence Zone contributes to the 20% hemispheric CF asymmetry between the tropical North and South Atlantic. This leads to the imbalance in strong solar radiation, which reaches the sea surface between the tropical North and South Atlantic, and, consequently, affects climate formation in the tropical Atlantic. Therefore, despite the fact that, over the global ocean, there is no noticeable hemispheric asymmetry in cloud fraction, over the significant area such as the tropical Atlantic the hemispheric asymmetry in CF takes place. Saharan dust is also the major contributor to hemispheric aerosol asymmetry over the tropical Atlantic. The NASA GEOS-5 model with aerosol data assimilation was used to extend the MERRA reanalysis with five atmospheric aerosol species (desert dust, sulfates, organic carbon, black carbon, and sea-salt). The obtained ten-year (2002 - 2012) MERRA-driven aerosol reanalysis dataset (aka MERRAero) showed that, over the tropical Atlantic, dust and carbonaceous aerosols were distributed asymmetrically relative to the equator, while other aerosol species were distributed more symmetrically.

  13. Tropical radioecology

    CERN Document Server

    Baxter, M

    2012-01-01

    Tropical Radioecology is a guide to the wide range of scientific practices and principles of this multidisciplinary field. It brings together past and present studies in the tropical and sub-tropical areas of the planet, highlighting the unique aspects of tropical systems. Until recently, radioecological models for tropical environments have depended upon data derived from temperate environments, despite the differences of these regions in terms of biota and abiotic conditions. Since radioactivity can be used to trace environmental processes in humans and other biota, this book offers examples of studies in which radiotracers have been used to assess biokinetics in tropical biota. Features chapters, co-authored by world experts, that explain the origins, inputs, distribution, behaviour, and consequences of radioactivity in tropical and subtropical systems. Provides comprehensive lists of relevant data and identifies current knowledge gaps to allow for targeted radioecological research in the future. Integrate...

  14. Variabilidade das anomalias de temperatura da superfície do mar no oceano atlântico sudoeste e sua relação com o fenomeno El Niño-Oscilação Sul Sea surface temperature anomaly variability in the southwestern atlantic ocean and its relationship with the El Niño - Southern Oscillation

    Directory of Open Access Journals (Sweden)

    Mariana Altenburg Soppa

    2011-09-01

    Full Text Available Este trabalho apresenta um estudo sobre a variabilidade dos campos de anomalia da temperatura da superfície do mar (ATSM, obtidos através imagens de satélites em regiões sob a influência dos diferentes regimes oceanográficos e/ou biofísicos no Oceano Atlântico Sudoeste (ATS. Para tanto, séries temporais de ATSM de 1985 a 2006 foram investigadas em nove sub-áreas no ATS, divididas nos domínios subtropical, intermediário e subantártico. Análise espectral aplicada às séries de ATSM revelou ciclos no período interanual entre 1,6 e 3,7 anos. Análise de correlação cruzada foi usada para estabelecer a relação entre os ciclos presentes na ATSM e os eventos do fenômeno El Niño Oscilação Sul (ENOS, representados aqui a partir do Índice Multivariado do ENOS (MEI. Os resultados evidenciam uma correlação estatisticamente significante, defasada no tempo, entre o ENOS e anomalias termais no ATS, porém sem uma associação direta entre os episódios quentes (frios de El Niño (La Niña e ATSMs positivas (negativas. Dentre as diversas áreas de estudo, a correlação é máxima sobre a região da Confluência Brasil-Malvinas (-0,78, com defasagem de tempo de 9 meses após a La Niña de maio de 1988 a maio de 1989.This work presents a study on the variability of satellite-derived sea surface temperature anomaly (SSTA fields in regions under the influence of different oceanographic and/or biophysical patterns in the South-western Atlantic Ocean (SWA. In order to accomplish that, time series of SSTA from 1985 to 2006 were investigated over nine sub-areas in the SWA, divided into the subtropical, intermediate and sub Antarctic domains. Spectral analysis applied to the SSTA time series reveled cycles in the interannual period between 1.6 and 3.7 years. Cross correlation analysis was used aiming to establish the relation between the cycles present in the SSTA and the El Niño - Southern Oscillation (ENSO events, represented here by the

  15. Sea surface salinity variability during the Indian Ocean Dipole and ENSO events in the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Grunseich, G.; Subrahmanyam, B.; Murty, V.S.N.; Giese, B.S.

    into the southwestern tropical Indian Ocean. The impact of concomitant La Niña with negative IOD is also large with an intense freshening in the southeastern Arabian Sea and salting off the northern Sumatra coast....

  16. Atlantic hurricane activity during the last millennium

    Science.gov (United States)

    Burn, Michael J.; Palmer, Suzanne E.

    2015-01-01

    Hurricanes are a persistent socio-economic hazard for countries situated in and around the Main Development Region (MDR) of Atlantic tropical cyclones. Climate-model simulations have attributed their interdecadal variability to changes in solar and volcanic activity, Saharan dust flux, anthropogenic greenhouse gas and aerosol emissions and heat transport within the global ocean conveyor belt. However, the attribution of hurricane activity to specific forcing factors is hampered by the short observational record of Atlantic storms. Here, we present the Extended Hurricane Activity (EHA) index, the first empirical reconstruction of Atlantic tropical cyclone activity for the last millennium, derived from a high-resolution lake sediment geochemical record from Jamaica. The EHA correlates significantly with decadal changes in tropical Atlantic sea surface temperatures (SSTs; r = 0.68; 1854–2008), the Accumulated Cyclone Energy index (ACE; r = 0.90; 1851–2010), and two annually-resolved coral-based SST reconstructions (1773–2008) from within the MDR. Our results corroborate evidence for the increasing trend of hurricane activity during the Industrial Era; however, we show that contemporary activity has not exceeded the range of natural climate variability exhibited during the last millennium. PMID:26243340

  17. Atlantic hurricane activity during the last millennium

    Science.gov (United States)

    Burn, Michael J.; Palmer, Suzanne E.

    2015-08-01

    Hurricanes are a persistent socio-economic hazard for countries situated in and around the Main Development Region (MDR) of Atlantic tropical cyclones. Climate-model simulations have attributed their interdecadal variability to changes in solar and volcanic activity, Saharan dust flux, anthropogenic greenhouse gas and aerosol emissions and heat transport within the global ocean conveyor belt. However, the attribution of hurricane activity to specific forcing factors is hampered by the short observational record of Atlantic storms. Here, we present the Extended Hurricane Activity (EHA) index, the first empirical reconstruction of Atlantic tropical cyclone activity for the last millennium, derived from a high-resolution lake sediment geochemical record from Jamaica. The EHA correlates significantly with decadal changes in tropical Atlantic sea surface temperatures (SSTs; r = 0.68 1854-2008), the Accumulated Cyclone Energy index (ACE; r = 0.90 1851-2010), and two annually-resolved coral-based SST reconstructions (1773-2008) from within the MDR. Our results corroborate evidence for the increasing trend of hurricane activity during the Industrial Era; however, we show that contemporary activity has not exceeded the range of natural climate variability exhibited during the last millennium.

  18. Atlantic hurricane activity during the last millennium.

    Science.gov (United States)

    Burn, Michael J; Palmer, Suzanne E

    2015-08-05

    Hurricanes are a persistent socio-economic hazard for countries situated in and around the Main Development Region (MDR) of Atlantic tropical cyclones. Climate-model simulations have attributed their interdecadal variability to changes in solar and volcanic activity, Saharan dust flux, anthropogenic greenhouse gas and aerosol emissions and heat transport within the global ocean conveyor belt. However, the attribution of hurricane activity to specific forcing factors is hampered by the short observational record of Atlantic storms. Here, we present the Extended Hurricane Activity (EHA) index, the first empirical reconstruction of Atlantic tropical cyclone activity for the last millennium, derived from a high-resolution lake sediment geochemical record from Jamaica. The EHA correlates significantly with decadal changes in tropical Atlantic sea surface temperatures (SSTs; r = 0.68; 1854-2008), the Accumulated Cyclone Energy index (ACE; r = 0.90; 1851-2010), and two annually-resolved coral-based SST reconstructions (1773-2008) from within the MDR. Our results corroborate evidence for the increasing trend of hurricane activity during the Industrial Era; however, we show that contemporary activity has not exceeded the range of natural climate variability exhibited during the last millennium.

  19. Genetic diversity of Ascaris in southwestern Uganda.

    Science.gov (United States)

    Betson, Martha; Nejsum, Peter; Llewellyn-Hughes, Julia; Griffin, Claire; Atuhaire, Aaron; Arinaitwe, Moses; Adriko, Moses; Ruggiana, Andrew; Turyakira, Grace; Kabatereine, Narcis B; Stothard, J Russell

    2012-02-01

    Despite the common occurrence of ascariasis in southwestern Uganda, helminth control in the region has been limited. To gain further insights into the genetic diversity of Ascaris in this area, a parasitological survey in mothers (n=41) and children (n=74) living in two villages, Habutobere and Musezero, was carried out. Adult Ascaris worms were collected from infected individuals by chemo-expulsion using pyrantel pamoate treatment. Genetic diversity within these worms was assessed by inspection of DNA sequence variation in a mitochondrial marker and length polymorphism at microsatellite loci. Overall prevalence of ascariasis was 42.5% in mothers and 30.4% in their children and a total of 98 worms was examined from 18 hosts. Sequence analysis of a portion of the mitochondrial cytochrome c oxidase subunit 1 gene revealed 19 different haplotypes, 13 of which had not been previously encountered. Microsatellite analysis using eight loci provided evidence for high gene flow between worm populations from the two villages but comparing these worms with others obtained in a prior study on Unguja, Zanzibar, confirmed little genetic exchange and mixing of worm populations between the two areas. By adding to our understanding of the genetic diversity of Ascaris in Africa, this study provides useful information for monitoring changes in parasite population structure in the face of ongoing and future control. Copyright © 2011 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

  20. Tropical Veterinarian

    African Journals Online (AJOL)

    TROPICAL VETERINARIAN is an international journal devoted to all aspects of veterinary science as practiced in the tropics, including livestock production and management, animal disease (domestic and wild), various aspects of preventive medicine and public health and basic and applied research in these areas.

  1. Oceanographic temperature and salinity profile data from bottle and CTD casts aboard multiple platforms in the South Atlantic Ocean from 1995-01-04 to 1998-12-19 (NCEI Accession 0143331)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bottle and CTD data collected in the Southwestern Atlantic Ocean during fisheries research cruises organized by the Instituto Nacional de Investigacion y Desarrollo...

  2. A biogeographical study on tropical flora of southern China.

    Science.gov (United States)

    Zhu, Hua

    2017-12-01

    The tropical climate in China exists in southeastern Xizang (Tibet), southwestern to southeastern Yunnan, southwestern Guangxi, southern Guangdon, southern Taiwan, and Hainan, and these southern Chinese areas contain tropical floras. I checked and synonymized native seed plants from these tropical areas in China and recognized 12,844 species of seed plants included in 2,181 genera and 227 families. In the tropical flora of southern China, the families are mainly distributed in tropical areas and extend into temperate zones and contribute to the majority of the taxa present. The genera with tropical distributions also make up the most of the total flora. In terms of geographical elements, the genera with tropical Asian distribution constitute the highest proportion, which implies tropical Asian or Indo-Malaysia affinity. Floristic composition and geographical elements are conspicuous from region to region due to different geological history and ecological environments, although floristic similarities from these regions are more than 90% and 64% at the family and generic levels, respectively, but lower than 50% at specific level. These differences in the regional floras could be influenced by historical events associated with the uplift of the Himalayas, such as the southeastward extrusion of the Indochina geoblock, clockwise rotation and southeastward movement of Lanping-Simao geoblock, and southeastward movement of Hainan Island. The similarity coefficients between the flora of southern China and those of Indochina countries are more than 96% and 80% at family and generic levels, indicating their close floristic affinity and inclusion in the same biogeographically floristic unit.

  3. Resolving Tropical Cyclone Intensity in Models

    Science.gov (United States)

    Davis, C. A.

    2018-02-01

    In recent years, global weather forecast models and global climate models have begun to depict intense tropical cyclones, even up to category 5 on the Saffir-Simpson scale. In light of the limitation of horizontal resolution in such models, the author performs calculations, using the extended Best Track data for Atlantic tropical cyclones, to estimate the ability of models with differing grid spacing to represent Atlantic tropical cyclone intensity statistically. Results indicate that, under optimistic assumptions, models with horizontal grid spacing of one fourth degree or coarser should not produce a realistic number of category 4 and 5 storms unless there are errors in spatial attributes of the wind field. Furthermore, the case of Irma (2017) is used to demonstrate the importance of a realistic depiction of angular momentum and to motivate the use of angular momentum in model evaluation.

  4. Atlantic Warm Pool Trigger for the Younger Dryas Climate Event

    Science.gov (United States)

    Abdul, N. A.; Mortlock, R. A.; Wright, J. D.; Fairbanks, R. G.; Teneva, L. T.

    2011-12-01

    There is growing evidence that variability in the size and heat content of the tropical Atlantic Warm Pool impacts circum-North Atlantic climate via the Atlantic Multi-decadal Oscillation mode (Wang et al., 2008). The Atlantic Warm Pool spans the Gulf of Mexico, Caribbean Sea and the western tropical North Atlantic. Barbados is located near the center of the tropical Atlantic Warm Pool and coupled ocean models suggest that Barbados remains near the center of the tropical Atlantic Warm Pool under varying wind stress simulations. Measurements of the oxygen isotope paleothermometer in Acropora palmata coral species recovered from cores offshore Barbados, show a 3oC monotonic decrease in sea surface temperature from 13106 ± 83 to 12744 ± 61 years before present (errors given as 2 sigma). This interval corresponds to a sea level rise from 71.4 meters to 67.1 meters below present levels at Barbados. The 3oC temperature decrease is captured in eight A. palmata specimens that are in stratigraphic sequence, 230Th/234U dated, and analyzed for oxygen isotopes. All measurements are replicated. We are confident that this is the warm pool equivalent of the Younger Dryas climate event. The initiation of this temperature drop in the Atlantic Warm Pool predates the Younger Dryas start in Greenland ice cores, reported to start at 12896 ± 138 years (relative to AD 2000) (Rasmussen et al., 2006), while few other Younger Dryas climate records are dated with similar accuracy to make the comparison. Rasmussen, S.O., Andersen, K.K., Svensson, A.M., Steffensen, J.P., Vinther, B.M., Clausen, H.B., Siggaard-Andersen, M.L., Johnsen, S.J., Larsen, L.B., Dahl-Jensen, D., Bigler, M., Röthlisberger, R., Fischer, H., Goto-Azuma, K., Hansson, M.E., and Ruth, U., 2006, A new Greenland ice core chronology for the last glacial termination: J. Geophys. Res., v. 111, p. D06102. Wang, C., Lee, S.-K., and Enfield, D.B., 2008, Atlantic Warm Pool acting as a link between Atlantic Multidecadal

  5. Southwestern Power Administration Update, October- December 2004

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-12-01

    On October 29, 2004, Southwestern and Southwest Power Pool, Inc. (SPP) reached agreement on interim arrangements to be implemented after the October 31, 2004, expiration of the membership agreement between the two parties. According to Jim McDonald, Director of Southwestern’s Division of Customer Service, the interim agreement forged between Southwestern and SPP seeks to minimize impacts to SPP as well as to Southwestern and its customers while Southwestern and SPP work on a seams/coordination agreement to succeed the expired membership agreement.

  6. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

    2004-01-01

    .... The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved advisories...

  7. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L; Cardone, Vincent J; Cox, Andrew T; Augustus, Ellsworth H; Colonnese, Christopher P

    2003-01-01

    .... The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved advisories...

  8. Real-Time Forecasting System of Winds, Waves and Surge in Tropical Cyclones

    National Research Council Canada - National Science Library

    Graber, Hans C; Donelan, Mark A; Brown, Michael G; Slinn, Donald N; Hagen, Scott C; Thompson, Donald R; Jensen, Robert E; Black, Peter G; Powell, Mark D; Guiney, John L

    2005-01-01

    .... The results of this forecasting system would provide real-time information to the National Hurricane Center during the tropical cyclone season in the Atlantic for establishing improved advisories...

  9. Tropical Cyclogenesis in a Tropical Wave Critical Layer: Easterly Waves

    Science.gov (United States)

    Dunkerton, T. J.; Montgomery, M. T.; Wang, Z.

    2009-01-01

    The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside.

  10. Stable isotope ratio measurements of Cu and Zn in mineral dust (bulk and size fractions) from the Taklimakan Desert and the Sahel and in aerosols from the eastern tropical North Atlantic Ocean.

    Science.gov (United States)

    Dong, Shuofei; Weiss, Dominik J; Strekopytov, Stanislav; Kreissig, Katharina; Sun, Youbin; Baker, Alex R; Formenti, Paola

    2013-09-30

    Accurate characterization of the stable isotope composition of Cu and Zn in major global mineral dust sources and in aerosols is central to the application of these isotope systems to the studies of global geochemical processes and cycles. We test here for the first time Cu and Zn isotope ratios within a well-defined source-receptor setting on the continent-ocean interface and determine the isotope composition of (i) bulk surface soil dust samples from the Sahel region, (ii) individual size fractions of surface dust samples from the Taklimakan Desert, and (iii) aerosols collected in the equatorial eastern North Atlantic region. This is achieved reducing the blank contribution during the ion exchange step using small resin and acid volumes and using a second ion exchange passage to purify the Cu fraction. We find no significant correlation between size fractions and isotope ratios in the two samples analyzed from the Taklimakan Desert. Mass balance calculations suggest that isotope ratios of bulk samples are within the analytical precision of the Sahel surface soil dust suggesting important non-crustal sources, in line with calculated enrichment factors, and possibly of anthropogenic origin. Using previously reported δ(66)Zn values for anthropogenic emission from Europe, preliminary calculations suggest that up to 55% of Zn arriving at the sampling points in the equatorial eastern North Atlantic region could be of anthropogenic origin. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Paleoceanography. Onset of Mediterranean outflow into the North Atlantic.

    Science.gov (United States)

    Hernández-Molina, F Javier; Stow, Dorrik A V; Alvarez-Zarikian, Carlos A; Acton, Gary; Bahr, André; Balestra, Barbara; Ducassou, Emmanuelle; Flood, Roger; Flores, José-Abel; Furota, Satoshi; Grunert, Patrick; Hodell, David; Jimenez-Espejo, Francisco; Kim, Jin Kyoung; Krissek, Lawrence; Kuroda, Junichiro; Li, Baohua; Llave, Estefania; Lofi, Johanna; Lourens, Lucas; Miller, Madeline; Nanayama, Futoshi; Nishida, Naohisa; Richter, Carl; Roque, Cristina; Pereira, Hélder; Sanchez Goñi, Maria Fernanda; Sierro, Francisco J; Singh, Arun Deo; Sloss, Craig; Takashimizu, Yasuhiro; Tzanova, Alexandrina; Voelker, Antje; Williams, Trevor; Xuan, Chuang

    2014-06-13

    Sediments cored along the southwestern Iberian margin during Integrated Ocean Drilling Program Expedition 339 provide constraints on Mediterranean Outflow Water (MOW) circulation patterns from the Pliocene epoch to the present day. After the Strait of Gibraltar opened (5.33 million years ago), a limited volume of MOW entered the Atlantic. Depositional hiatuses indicate erosion by bottom currents related to higher volumes of MOW circulating into the North Atlantic, beginning in the late Pliocene. The hiatuses coincide with regional tectonic events and changes in global thermohaline circulation (THC). This suggests that MOW influenced Atlantic Meridional Overturning Circulation (AMOC), THC, and climatic shifts by contributing a component of warm, saline water to northern latitudes while in turn being influenced by plate tectonics. Copyright © 2014, American Association for the Advancement of Science.

  12. South Atlantic Shrimp System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SEFSC, in cooperation with the South Atlantic states, collects South Atlantic shrimp data from dealers and fishermen. These data are collected to provide catch,...

  13. 2005 Atlantic Hurricanes Poster

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 2005 Atlantic Hurricanes poster features high quality satellite images of 15 hurricanes which formed in the Atlantic Basin (includes Gulf of Mexico and Caribbean...

  14. Return of naturally sourced Pb to Atlantic surface waters

    NARCIS (Netherlands)

    Bridgestock, Luke; van de Flierdt, Tina; Rehkamper, Mark; Paul, Maxence; Middag, Rob; Milne, Angela; Lohan, Maeve C.; Baker, Alex R.; Chance, Rosie; Khondoker, Roulin; Strekopytov, Stanislav; Humphreys-Williams, Emma; Achterberg, Eric P.; Rijkenberg, Micha J. A.; Gerringa, Loes J. A.; de Baar, Henricus

    Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources during the past century, predominantly due to leaded petrol usage. Here, based on Pb isotope measurements, we reassess the importance of natural and anthropogenic Pb sources to the tropical North Atlantic following the

  15. Temperature, salinity, oxygen, zooplankton biomass, zooplankton count, phytoplankton count, and fish count measurements collected from multiple Soviet Union research vessels in the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico from 1963-03-09 to 1989-11-20 (NODC Accession 0001310)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Collection of physical, chemical, and biological data presented on CD-ROM "Pelagic Ecosystems of the Tropical Atlantic Ocean". Data were collected from Atlantic...

  16. Tropical Deforestation.

    Science.gov (United States)

    Raven, Peter H.

    1988-01-01

    Outlines the deforestation problem and some efforts for solving the problem. Considers the impact of population growth, poverty, and ignorance. Includes a discussion of the current rapid decline in tropical forests, the consequences of destruction, and an outlook for the future. (YP)

  17. Physical trajectory profile data from glider SG547 deployed by US DOC; NOAA; OAR; Atlantic Oceanographic and Meteorological Laboratory in the North Atlantic Ocean from 2016-08-04 to 2016-11-02 (NCEI Accession 0157712)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  18. Physical trajectory profile data from glider SG610 deployed by US DOC; NOAA; OAR; Atlantic Oceanographic and Meteorological Laboratory in the North Atlantic Ocean from 2016-08-04 to 2016-11-01 (NCEI Accession 0157656)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  19. Oceanographic temperature, salinity, and oxygen profiles from CTDs aboard the R/V ENDEAVOR during the cruise PNE2014 in the North Atlantic and Equatorial Atlantic from 2015-1-3 to 2015-2-6 (NODC Accession 0126985)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 2014 PIRATA Northeast Extension Cruise EN-550 was designed to collect observations in the northeast Tropical Atlantic, to service the northeast extension of the...

  20. Oceanographic profile temperature, salinity and other measurements using CTD taken from NOAA Ship RONALD H. BROWN in the North Atlantic and Equatorial Atlantic from 2013-11-16 to 2013-12-05 (NODC Accession 0120702)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The November - December 2013 PIRATA (Prediction and Research Moored Array in the Tropical Atlantic) Northeast Extension (PNE) and Aerosols and Ocean Science...

  1. Physical trajectory profile data from glider SG609 deployed by Atlantic Oceanographic and Meteorological Laboratory in the North Atlantic Ocean from 2014-07-19 to 2014-11-18 (NCEI Accession 0131705)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  2. Physical trajectory profile data from glider SG610 deployed by Atlantic Oceanographic and Meteorological Laboratory in the North Atlantic Ocean from 2015-08-11 to 2015-11-18 (NCEI Accession 0145656)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  3. ON THE INFLUENCE OF GLOBAL WARMING ON ATLANTIC HURRICANE FREQUENCY

    Directory of Open Access Journals (Sweden)

    S. R. Hosseini

    2018-04-01

    Full Text Available In this paper, the possible connection between the frequency of Atlantic hurricanes to the climate change, mainly the variation in the Atlantic Ocean surface temperature has been investigated. The correlation between the observed hurricane frequency for different categories of hurricane’s intensity and Sea Surface Temperature (SST has been examined over the Atlantic Tropical Cyclogenesis Regions (ACR. The results suggest that in general, the frequency of hurricanes have a high correlation with SST. In particular, the frequency of extreme hurricanes with Category 5 intensity has the highest correlation coefficient (R = 0.82. In overall, the analyses in this work demonstrates the influence of the climate change condition on the Atlantic hurricanes and suggest a strong correlation between the frequency of extreme hurricanes and SST in the ACR.

  4. Decapod assemblages in subtidal and intertidal zones—Importance of scuba diving as a survey technique in tropical reefs, Brazil

    Directory of Open Access Journals (Sweden)

    Bruno Welter Giraldes

    2015-01-01

    Full Text Available Decapods play a crucial role within the reef ecosystem and the development of scuba diving as a survey tool has allowed researchers the opportunity to study the decapod–reef relationship more comprehensively. The present study describes the differences in decapod assemblages in intertidal and subtidal zones at a tropical coastal reef system in the southwestern Atlantic Ocean and reports the importance of scuba diving as a survey technique. A total of 71 decapods were recorded during the research; 42 in the intertidal zone mainly formed by small endobenthic species and 39 in the subtidal zone primarily large species only 10 were found to frequent both sample zones. The study extends the range of Brachycarpusholthuisi Fausto Filho 1966 in Brazil; and also demonstrates how scuba diving can be used to complement traditional methodologies and vice versa. The research shows the advantages of using scuba diving when studying trade endangered decapods, as the methodology allows access to cryptic habitats such as reef caves and underwater cavities which were inaccessible when using traditional techniques. In conclusion scuba diving represents a revolutionary non-destructive survey tool allowing the researcher to directly access a specific decapod assemblage in fragile reef environments and in protected marine areas.

  5. Bird diversity and conservation of Alto Balsas (southwestern Puebla), Mexico.

    Science.gov (United States)

    Ramírez-Albores, Jorge E

    2007-03-01

    Knowledge of the composition of the bird community in Alto Balsas (southwestern Puebla, Central Mexico) is needed for management programs aiming at protection and conservation of bird species and their habitats I studied sites with tropical deciduous forest. Data were obtained during 1666 hours of field work in 238 days from March 1998 to September 2000. Six permanent transect (3.5 km long and 100 m wide; 30 to 40 ha in each transect) were used to determine species richness in the study sites. The Shannon-Wiener diversity index was calculated for each site and Sorensen's index was used to assess similarity between sites. One-way analysis of variance was used to test for differences between sites in species richness and diversity values. A total of 128 species were recorded, Tepexco (n=75, H' = 3.76) and Puente Márquez (n=61, H' = 3.62) were the sites that showed the greatest specific richness and diversity. However, species richness and diversity seasonally patterns were similar among sites (ANOVA p > 0.05), with highest diversity during the rainy season. Most species were resident; 42 were migrants. The avifauna was represented by 30 species associated with tropical deciduous forest and 12 from open habitats or heavily altered habitats. Insectivores were the best represented trophic category, followed by carnivores and omnivores.

  6. A Review of ENSO Influence on the North Atlantic. A Non-Stationary Signal

    Directory of Open Access Journals (Sweden)

    Belén Rodríguez-Fonseca

    2016-06-01

    Full Text Available The atmospheric seasonal cycle of the North Atlantic region is dominated by meridional movements of the circulation systems: from the tropics, where the West African Monsoon and extreme tropical weather events take place, to the extratropics, where the circulation is dominated by seasonal changes in the jetstream and extratropical cyclones. Climate variability over the North Atlantic is controlled by various mechanisms. Atmospheric internal variability plays a crucial role in the mid-latitudes. However, El Niño-Southern Oscillation (ENSO is still the main source of predictability in this region situated far away from the Pacific. Although the ENSO influence over tropical and extra-tropical areas is related to different physical mechanisms, in both regions this teleconnection seems to be non-stationary in time and modulated by multidecadal changes of the mean flow. Nowadays, long observational records (greater than 100 years and modeling projects (e.g., CMIP permit detecting non-stationarities in the influence of ENSO over the Atlantic basin, and further analyzing its potential mechanisms. The present article reviews the ENSO influence over the Atlantic region, paying special attention to the stability of this teleconnection over time and the possible modulators. Evidence is given that the ENSO–Atlantic teleconnection is weak over the North Atlantic. In this regard, the multidecadal ocean variability seems to modulate the presence of teleconnections, which can lead to important impacts of ENSO and to open windows of opportunity for seasonal predictability.

  7. Fluvial landscape development in the southwestern Kalahari during the Holocene - Chronology and provenance of fluvial deposits in the Molopo Canyon

    DEFF Research Database (Denmark)

    Ramisch, Arne; Bens, Oliver; Buylaert, Jan-Pieter

    2017-01-01

    are sparse and often discontinuous. Hence, little is known about Holocene environmental change in this region. This study focuses on reconstructing paleoenvironmental change from the timing and provenance of fluvial deposits located within the Molopo Canyon, which connects the southern Kalahari drainage......The southern Kalahari drainage network is in a key position to analyze spatiotemporal changes in the tropical easterly and the temperate westerly circulation over the Southern African subcontinent. However, due to the prevailing aridity, paleoenvironmental archives within the southwestern Kalahari...

  8. Southwestern Power Administration Annual Report 2012

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-09-01

    Dear Secretary Moniz: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2012. In FY 2012, Southwestern delivered over 4.1 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas, generating $195 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  9. Southwestern Power Administration Annual Report 2010

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-09-01

    Dear Secretary Chu: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2010. In FY 2010, Southwestern delivered nearly 7.6 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Texas, and Oklahoma, generating $189 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  10. Southwestern Power Administration Annual Report 2011

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-04-01

    Dear Secretary Chu: I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2011. In FY 2011, Southwestern delivered over 4.1 billion kilowatt-hours of energy to its wholesale customers in Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas, generating $167 million in revenue. In fulfilling its mission to market and reliably deliver renewable Federal hydroelectric power, Southwestern maintains 1,380 miles of high-voltage transmission lines, substations, and communications sites, contributing to the reliability of the regional and National electric grid. Southwestern also actively partners with the Department of Energy, the U.S. Army Corps of Engineers, Southwestern’s customers, and other Federal power stakeholders to most effectively balance their diverse interests with Southwestern’s mission while continuing to maximize Federal assets to repay the Federal investment in the 24 hydropower facilities within Southwestern’s marketing region. Southwestern is proud of its past successes, and we look forward to continuing to serve the Nation’s energy needs in the future. Sincerely, Christopher M. Turner Administrator

  11. Orchid conservation in the biodiversity hotspot of southwestern China.

    Science.gov (United States)

    Liu, Qiang; Chen, Jin; Corlett, Richard T; Fan, XuLi; Yu, DongLi; Yang, HongPei; Gao, JiangYun

    2015-12-01

    Xishuangbanna is on the northern margins of tropical Asia in southwestern China and has the largest area of tropical forest remaining in the country. It is in the Indo-Burma hotspot and contains 16% of China's vascular flora in biodiversity. To understand the effects of land-use change and collection on orchid species diversity and determine protection priorities, we conducted systematic field surveys, observed markets, interviewed orchid collectors, and then determined the conservation status of all orchids. We identified 426 orchid species in 115 genera in Xishuangbanna: 31% of all orchid species that occur in China. Species richness was highest at 1000-1200 m elevation. Three orchid species were assessed as possibly extinct in the wild, 15 as critically endangered, 82 as endangered, 124 as vulnerable, 186 as least concern, and 16 as data deficient. Declines over 20 years in harvested species suggested over-collection was the major threat, and utility value (i.e., medicinal or ornamental value) was significantly related to endangerment. Expansion of rubber tree plantations was less of a threat to orchids than to other taxa because only 75 orchid species (17.6%) occurred below the 1000-m-elevation ceiling for rubber cultivation, and most of these (46) occurred in nature reserves. However, climate change is projected to lift this ceiling to around 1300 m by 2050, and the limited area at higher elevations reduces the potential for upslope range expansion. The Xishuangbanna Tropical Botanical Garden is committed to achieving zero plant extinctions in Xishuangbanna, and orchids are a high priority. Appropriate in and ex situ conservation strategies, including new protected areas and seed banking, have been developed for every threatened orchid species and are being implemented. © 2015 Society for Conservation Biology.

  12. Enhanced biennial variability in the Pacific due to Atlantic capacitor effect.

    Science.gov (United States)

    Wang, Lei; Yu, Jin-Yi; Paek, Houk

    2017-03-20

    The El Niño-Southern Oscillation (ENSO) and the variability in the Pacific subtropical highs (PSHs) have major impacts on social and ecological systems. Here we present an Atlantic capacitor effect mechanism to suggest that the Atlantic is a key pacemaker of the biennial variability in the Pacific including that in ENSO and the PSHs during recent decades. The 'charging' (that is, ENSO imprinting the North Tropical Atlantic (NTA) sea surface temperature (SST) via an atmospheric bridge mechanism) and 'discharging' (that is, the NTA SST triggering the following ENSO via a subtropical teleconnection mechanism) processes alternate, generating the biennial rhythmic changes in the Pacific. Since the early 1990s, a warmer Atlantic due to the positive phase of Atlantic multidecadal oscillation and global warming trend has provided more favourable background state for the Atlantic capacitor effect, giving rise to enhanced biennial variability in the Pacific that may increase the occurrence frequency of severe natural hazard events.

  13. The forcing of southwestern Asia teleconnections by low-frequency sea surface temperature variability during boreal winter

    Science.gov (United States)

    Hoell, Andrew; Funk, Christopher C.; Mathew Barlow,

    2015-01-01

    Southwestern Asia, defined here as the domain bounded by 20°–40°N and 40°–70°E, which includes the nations of Iraq, Iran, Afghanistan, and Pakistan, is a water-stressed and semiarid region that receives roughly 75% of its annual rainfall during November–April. The November–April climate of southwestern Asia is strongly influenced by tropical Indo-Pacific variability on intraseasonal and interannual time scales, much of which can be attributed to sea surface temperature (SST) variations. The influences of lower-frequency SST variability on southwestern Asia climate during November–April Pacific decadal SST (PDSST) variability and the long-term trend in SST (LTSST) is examined. The U.S. Climate Variability and Predictability Program (CLIVAR) Drought Working Group forced global atmospheric climate models with PDSST and LTSST patterns, identified using empirical orthogonal functions, to show the steady atmospheric response to these modes of decadal to multidecadal SST variability. During November–April, LTSST forces an anticyclone over southwestern Asia, which results in reduced precipitation and increases in surface temperature. The precipitation and tropospheric circulation influences of LTSST are corroborated by independent observed precipitation and circulation datasets during 1901–2004. The decadal variations of southwestern Asia precipitation may be forced by PDSST variability, with two of the three models indicating that the cold phase of PDSST forces an anticyclone and precipitation reductions. However, there are intermodel circulation variations to PDSST that influence subregional precipitation patterns over the Middle East, southwestern Asia, and subtropical Asia. Changes in wintertime temperature and precipitation over southwestern Asia forced by LTSST and PDSST imply important changes to the land surface hydrology during the spring and summer.

  14. Classic Maya civilization collapse associated with reduction in tropical cyclone activity

    Science.gov (United States)

    Medina, M. A.; Polanco-Martinez, J. M.; Lases-Hernández, F.; Bradley, R. S.; Burns, S. J.

    2013-12-01

    In light of the increased destructiveness of tropical cyclones observed over recent decades one might assume that an increase and not a decrease in tropical cyclone activity would lead to societal stress and perhaps collapse of ancient cultures. In this study we present evidence that a reduction in the frequency and intensity of tropical Atlantic cyclones could have contributed to the collapse of the Maya civilization during the Terminal Classic Period (TCP, AD. 800-950). Statistical comparisons of a quantitative precipitation record from the Yucatan Peninsula (YP) Maya lowlands, based on the stalagmite known as Chaac (after the Mayan God of rain and agriculture), relative to environmental proxy records of El Niño/Southern Oscillation (ENSO), tropical Atlantic sea surface temperatures (SSTs), and tropical Atlantic cyclone counts, suggest that these records share significant coherent variability during the TCP and that summer rainfall reductions between 30 and 50% in the Maya lowlands occurred in association with decreased Atlantic tropical cyclones. Analysis of modern instrumental hydrological data suggests cyclone rainfall contributions to the YP equivalent to the range of rainfall deficits associated with decreased tropical cyclone activity during the collapse of the Maya civilization. Cyclone driven precipitation variability during the TCP, implies that climate change may have triggered Maya civilization collapse via freshwater scarcity for domestic use without significant detriment to agriculture. Pyramid in Tikal, the most prominent Maya Kingdom that collapsed during the Terminal Classic Period (circa C.E. 800-950) Rainfall feeding stalagmites inside Rio Secreto cave system, Yucatan, Mexico.

  15. Interactions of the tropical oceans. Rev.ed.

    International Nuclear Information System (INIS)

    Latif, M.; Barnett, T.P.

    1994-01-01

    We have investigated the interactions of the tropical oceans on interannual time scales by conducting a series of uncoupled atmospheric and oceanic general circulation experiments and hybrid coupled model simulations. Our results illustrate the key role of the El Nino/Southern Oscillation (ENSO) phenomenon in generating interannual variability in all three tropical ocean basins. Sea surface temperature (SST) anomalies in the tropical Pacific force via a changed atmospheric circulation SST anomalies of the same sign in the Indian Ocean and SST anomalies of the opposite sign in the Atlantic. However, although air-sea interactions in the Indian and Atlantic Oceans are much weaker than those in the Pacific, they contribute significantly to the variability in these two regions. The role of these air-sea interactions is mainly that of an amplifyer by which the ENSO induced signals are enhanced in ocean and atmosphere. This process is particularly important in the tropical Atlantic region. We investigated also whether ENSO is part of a zonally propagating ''wave'' which travels around the globe with a time scale of several years. Consistent with observations, the upper ocean heat content in the various numerical simulations seems to propagate slowly around the globe. SST anomalies in the Pacific Ocean introduce a global atmospheric response which in turn forces variations in the other tropical oceans. Since the different oceans exhibit different response characteristics to low-frequency wind changes, the individual tropical ocean responses can add up coincidentally to look like a global wave, and that appears to be the situation. In particular, no evidence is found that the Indian Ocean can significantly affect the ENSO cycle in the Pacific. Finally, the potential for climate forecasts in the Indian and Atlantic Oceans appears to be enhanced if one includes, in a coupled way, remote influences from the Pacific. (orig.)

  16. [The geopolitics of tropical diseases: a geo-epidemiological perspective].

    Science.gov (United States)

    Lee, Jong-Chan

    2005-12-01

    The objective of my article is to investigate how the West had strong interest in tropical diseases and developed tropical medicine and hygiene from the 1870s through the 1910s. Its focus is to identify the geopolitical conditions in which the West constructed 'tropical diseases' to extend its imperial interests into non-Western tropical regions. The article has several specific research tasks: first, I attempt to explore the way in which European people transformed their attitudes toward tropical diseases from the sixteenth century to the 1860s. A variety of writings by European physicians are discussed; the second part shows European change in its domestic sanitary situation in relation to its imperial interests in tropical regions. Sanitary hygiene in metropole and colonies are not separate, but interconnected; third, the paper illuminates how the West responded to the spread of 'Asiatic cholera' in the nineteenth century. Cholera provides a typical example for the West to perceive Asian origin of tropical diseases; finally, the article demonstrates that hygienic governance of tropical diseases is the key to imperial dominion over colonies by taking the Panama Canal as an example. Although several European countries such as Spain, Britain, Germany, and France had strong imperial interests in the Panama Canal that might facilitate trade between the Atlantic and the Pacific, they failed to occupy the canal because of their inability to control high prevalence of malaria and yellow fever. Taking advantage of 'tropical medicine,' the United States succeeded in taking up the canal by eradicating tropical diseases in the canal. It was owing to the scientific development of tropical hygiene and medicine that the West transformed its pessimistic into optimistic position about the colonization of tropical regions. Tropical diseases became the geopolitical reference for Western conceptualization of Asia, Africa, Latin America, and the Pacific.

  17. Diapycnal Diffusivities over the Southwestern Indian Ocean Ridge

    Science.gov (United States)

    Zhou, L.; Wang, Y.; Yang, Q.

    2016-02-01

    The southwestern Indian Ocean (SWIO) Ridge stems from the South Atlantic and extends northeastward to Rodrigues Island. The deep trenches and fracture zones between the Crozet Basin and the Madagascar Basin provide the major passages for the deep and the bottom water to enter the Indian Ocean, which is also part of the meridional overturning circulation (MOC) in the Indian Ocean. More than 70 CTD profiles have been conducted over the SWIO Ridge from 2010 up to now. Besides, a mooring was deployed about 2900 m below the sea surface for almost one year. Three Seaguard current meters, nine Sea-Bird Electronics Temperature-pressure sensor, and one Sea-Bird Electronics Temperature-Conductivity-Pressure Sensor were mounted on the mooring. The diapycnal diffusivity over the SWIO Ridge is estimated with two methods, i.e., the Internal Wave Spectrum Method (GHP) which relies on the energy cascade due to wave interactions, and the Thorpe scale method. Large diffusivities on the order of 10-2 m2 s-1 are found over the rough ridges. Moreover, the temporal and spatial distributions of diapycnal diffusivities are presented and their physical relations with the fine structure of the bottom topography are analyzed in this study.

  18. Atlantic effects on recent decadal trends in global monsoon

    Science.gov (United States)

    Kamae, Youichi; Li, Xichen; Xie, Shang-Ping; Ueda, Hiroaki

    2017-11-01

    Natural climate variability contributes to recent decadal climate trends. Specifically the trends during the satellite era since 1979 include Atlantic and Indian Ocean warming and Pacific cooling associated with phase shifts of the Atlantic Multidecadal Oscillation and the Pacific Decadal Oscillation, and enhanced global monsoon (GM) circulation and rainfall especially in the Northern Hemisphere. Here we evaluate effects of the oceanic changes on the global and regional monsoon trends by partial ocean temperature restoring experiments in a coupled atmosphere-ocean general circulation model. Via trans-basin atmosphere-ocean teleconnections, the Atlantic warming drives a global pattern of sea surface temperature change that resembles observations, giving rise to the enhanced GM. The tropical Atlantic warming and the resultant Indian Ocean warming favor subtropical deep-tropospheric warming in both hemispheres, resulting in the enhanced monsoon circulations and precipitation over North America, South America and North Africa. The extratropical North Atlantic warming makes an additional contribution to the monsoon enhancement via Eurasian continent warming and resultant land-sea thermal gradient over Asia. The results of this study suggest that the Atlantic multidecadal variability can explain a substantial part of global climate variability including the recent decadal trends of GM.

  19. Tropical cyclogenesis in a tropical wave critical layer: easterly waves

    Directory of Open Access Journals (Sweden)

    T. J. Dunkerton

    2009-08-01

    Full Text Available The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because its cat's eye provides (i a region of

  20. Longwave emission trends over Africa and implications for Atlantic hurricanes

    Science.gov (United States)

    Zhang, Lei; Rechtman, Thomas; Karnauskas, Kristopher B.; Li, Laifang; Donnelly, Jeffrey P.; Kossin, James P.

    2017-09-01

    The latitudinal gradient of outgoing longwave radiation (OLR) over Africa is a skillful and physically based predictor of seasonal Atlantic hurricane activity. The African OLR gradient is observed to have strengthened during the satellite era, as predicted by state-of-the-art global climate models (GCMs) in response to greenhouse gas forcing. Prior to the satellite era and the U.S. and European clean air acts, the African OLR gradient weakened due to aerosol forcing of the opposite sign. GCMs predict a continuation of the increasing OLR gradient in response to greenhouse gas forcing. Assuming a steady linear relationship between African easterly waves and tropical cyclogenesis, this result suggests a future increase in Atlantic tropical cyclone frequency by 10% (20%) at the end of the 21st century under the RCP 4.5 (8.5) forcing scenario.

  1. Casuses of deforestation in southwestern Madagascar

    DEFF Research Database (Denmark)

    Casse, Thorkil; Milhøj, Anders; Ranaivoson, Socrate

    2004-01-01

    Causes of deforestation are discussed in the case of southwestern Madagascar. Distinction is made between direct and indirect causes. The article ends up with an estimation of the value of agricultural land vs. an estimation of benefits from utilisation of non-timber forest products......Causes of deforestation are discussed in the case of southwestern Madagascar. Distinction is made between direct and indirect causes. The article ends up with an estimation of the value of agricultural land vs. an estimation of benefits from utilisation of non-timber forest products...

  2. Status, ecology, and conservation of the southwestern willow flycatcher

    Science.gov (United States)

    Deborah M. Finch; Scott H. Stoleson

    2000-01-01

    This publication was prepared in response to a need expressed by southwestern agencies and organizations for a comprehensive assessment of the population status, history, biology, ecology, habitats, threats, and conservation of the southwestern willow flycatcher (Empidonax traillii extimus). The southwestern willow flycatcher was federally listed as...

  3. Piomiosite tropical

    Directory of Open Access Journals (Sweden)

    Márcio José de Araújo Torres

    1978-12-01

    Full Text Available O autor descreve 7 casos de piomiosite tropical, enfatizando a exceção que constituem, quando se considera a extrema raridade da supuração muscular em outras doenças e citando várias idéias existentes quanto à sua patogenia. O quadro clínico dos 7 casos é semelhante à maioria dos já relatados em outros trabalhos, aparecendo entretanto piodermite em 2 doentes, o que não é comum. A freqüência da eosinofilia e a normalidade de enzimas geralmente elevadas em outras miopatias, estão de acordo com as publicações existentes. Embora o tratamento seja basicamente cirúrgico, aceita a possibilidade de cura com antibióticos, cujo uso empírico poderia abortar inúmeros casos, contribuindo para o virtual desconhecimento da doença no meio brasileiro. Considera provável ser grande número de doentes tratado como portadores de abscessos como quaisquer outros, sem se atentar para a já referida resistência dos músculos esqueléticos à supuração. Dá importância ao desconhecimento da doença como causa de demora no diagnóstico, com possíveis repercussões no prognóstico. Esse fato, aliado a semelhanças climáticas de certas regiões brasileiras com zonas africanas onde a incidência é alta, justifica, segundo o autor, maior interesse pela doença.Seven cases of tropical pyomyositis are reported emphasizing the unique character of muscular suppuration, an exceedingly unusual occurrence in other diseases; possible explanations as to the pathogenical mechanismsare reviewed. Clinical aspects are similar to those of previously described cases but for pyodermitis, an unconmmon feature found in two cases. Eosinophila and normal leveis of serum enzymes usually altered in other muscle diseases are also in accordance to previous papers. Surgical drainage is the treatment of choice, but the early administration of antibiotics might abort the evolution of many cases; the empirical use of such drugs modifies clinical course and most patients

  4. Plant litter dynamics in the forest-stream interface: precipitation is a major control across tropical biomes

    OpenAIRE

    Tonin, Alan M.; Gon?alves, Jos? F.; Bambi, Paulino; Couceiro, Sheyla R. M.; Feitoza, Lorrane A. M.; Fontana, Lucas E.; Hamada, Neusa; Hepp, Luiz U.; Lezan-Kowalczuk, V?nia G.; Leite, Gustavo F. M.; Lemes-Silva, Aurea L.; Lisboa, Leonardo K.; Loureiro, Rafael C.; Martins, Renato T.; Medeiros, Adriana O.

    2017-01-01

    Riparian plant litter is a major energy source for forested streams across the world and its decomposition has repercussions on nutrient cycling, food webs and ecosystem functioning. However, we know little about plant litter dynamics in tropical streams, even?though the tropics occupy 40% of the Earth?s land surface. Here we investigated spatial and temporal (along a year cycle) patterns of litter inputs and storage in multiple streams of three tropical biomes in Brazil (Atlantic forest, Ama...

  5. Piomiosite tropical

    Directory of Open Access Journals (Sweden)

    Márcio José de Araújo Torres

    1978-12-01

    Full Text Available O autor descreve 7 casos de piomiosite tropical, enfatizando a exceção que constituem, quando se considera a extrema raridade da supuração muscular em outras doenças e citando várias idéias existentes quanto à sua patogenia. O quadro clínico dos 7 casos é semelhante à maioria dos já relatados em outros trabalhos, aparecendo entretanto piodermite em 2 doentes, o que não é comum. A freqüência da eosinofilia e a normalidade de enzimas geralmente elevadas em outras miopatias, estão de acordo com as publicações existentes. Embora o tratamento seja basicamente cirúrgico, aceita a possibilidade de cura com antibióticos, cujo uso empírico poderia abortar inúmeros casos, contribuindo para o virtual desconhecimento da doença no meio brasileiro. Considera provável ser grande número de doentes tratado como portadores de abscessos como quaisquer outros, sem se atentar para a já referida resistência dos músculos esqueléticos à supuração. Dá importância ao desconhecimento da doença como causa de demora no diagnóstico, com possíveis repercussões no prognóstico. Esse fato, aliado a semelhanças climáticas de certas regiões brasileiras com zonas africanas onde a incidência é alta, justifica, segundo o autor, maior interesse pela doença.

  6. Atlantic Multidecadal Oscillation footprint on global high cloud cover

    Science.gov (United States)

    Vaideanu, Petru; Dima, Mihai; Voiculescu, Mirela

    2017-12-01

    Due to the complexity of the physical processes responsible for cloud formation and to the relatively short satellite database of continuous data records, cloud behavior in a warming climate remains uncertain. Identifying physical links between climate modes and clouds would contribute not only to a better understanding of the physical processes governing their formation and dynamics, but also to an improved representation of the clouds in climate models. Here, we identify the global footprint of the Atlantic Multidecadal Oscillation (AMO) on high cloud cover, with focus on the tropical and North Atlantic, tropical Pacific and on the circum-Antarctic sector. In the tropical band, the sea surface temperature (SST) and high cloud cover (HCC) anomalies are positively correlated, indicating a dominant role played by convection in mediating the influence of the AMO-related SST anomalies on the HCC field. The negative SST-HCC correlation observed in North Atlantic could be explained by the reduced meridional temperature gradient induced by the AMO positive phase, which would be reflected in less storms and negative HCC anomalies. A similar negative SST-HCC correlation is observed around Antarctica. The corresponding negative correlation around Antarctica could be generated dynamically, as a response to the intensified upward motion in the Ferrel cell. Despite the inherent imperfection of the observed and reanalysis data sets, the AMO footprint on HCC is found to be robust to the choice of dataset, statistical method, and specific time period considered.

  7. Geotechnical characteristics of some Southwestern Nigerian clays ...

    African Journals Online (AJOL)

    The geotechnical characteristics of some southwestern Nigeria clays were evaluated with a view to determining their suitability for use as barrier soils in waste disposal sites. Clay soils (consisting of twenty disturbed and twenty undisturbed samples) were subjected to grain size, consistency limits and permeability tests.

  8. Factors influencing woodlands of southwestern North Dakota

    Science.gov (United States)

    Michele M. Girard; Harold Goetz; Ardell J. Bjugstad

    1987-01-01

    Literature pertaining to woodlands of southwestern North Dakota is reviewed. Woodland species composition and distribution, and factors influencing woodland ecosystems such as climate, logging, fire, and grazing are described. Potential management and improvement techniques using vegetation and livestock manipulation have been suggested.

  9. Pig slaughtering in southwestern Nigeria: peculiarities, animal ...

    African Journals Online (AJOL)

    Pig slaughtering in southwestern Nigeria: peculiarities, animal welfare concerns and public health implications. ... pig slaughtering methods in the three locations vary considerably with some identified areas of animal welfare concerns which include inhumane transportation , restraining, lairaging, and stunning practices.s.

  10. Ecosystem biophysical memory in the southwestern North America climate system

    International Nuclear Information System (INIS)

    Forzieri, G; Feyen, L; Vivoni, E R

    2013-01-01

    To elucidate the potential role of vegetation to act as a memory source in the southwestern North America climate system, we explore correlation structures of remotely sensed vegetation dynamics with precipitation, temperature and teleconnection indices over 1982–2006 for six ecoregions. We found that lagged correlations between vegetation dynamics and climate variables are modulated by the dominance of monsoonal or Mediterranean regimes and ecosystem-specific physiological processes. Subtropical and tropical ecosystems exhibit a one month lag positive correlation with precipitation, a zero- to one-month lag negative correlation with temperature, and modest negative effects of sea surface temperature (SST). Mountain forests have a zero month lag negative correlation with precipitation, a zero–one month lag negative correlation with temperature, and no significant correlation with SSTs. Deserts show a strong one–four month lag positive correlation with precipitation, a low zero–two month lag negative correlation with temperature, and a high four–eight month lag positive correlation with SSTs. The ecoregion-specific biophysical memories identified offer an opportunity to improve the predictability of land–atmosphere interactions and vegetation feedbacks onto climate. (letter)

  11. GENETIC PARAMETERS FOR Hymenaea courbaril L. CONSERVATION IN SOUTHWESTERN AMAZON

    Directory of Open Access Journals (Sweden)

    Susana Maria Melo Silva

    2014-03-01

    Full Text Available http://dx.doi.org/10.5902/1980509813326The loss of diversity in tropical regions has been focus on several governmental and non-governmentaldiscussions, focusing mainly on the fragmentation and destruction of natural ecosystems. However,decisions about the conservation of genetic resources must be guided by population genetic parameters,especially for species with economic interests that are subject to greater human interference. This studyaimed to define and evaluate genetic parameters for the conservation of populations of Hymenaea courbarilin southwestern Amazon. This species is one of the most valuable and intensively exploited wood species inthe Brazilian Amazon. We studied three forest areas prepared for logging in the background of sustainablemanagement. It was calculated with eight microsatellite loci, genetic diversity, intra-population conservationestimators and genetic divergence among populations. Genetic diversity and fixation index were higher inthe low density populations (< 0.08 ind.ha-1. The most density population (0.25 ind.ha-1 showed the lowestgenetic diversity and no inbreeding. The Minimum Viable Area for species conservation was consistent with the reality of the studied areas, with a proviso for one of the populations where there is a need for amuch larger area than the other to conserve populations. The genetic divergence was high (G’ST = 0.344 andthe populations were considered Independent Management Units.

  12. Relação entre as vazões médias mensais do rio Piancó e as anomalias de temperatura da superfície dos oceanos Atlântico e Pacífico tropical Relationhips between monthly mean stream flow for the Pianco river and tropical Atlantic and Pacific sst anomalies

    Directory of Open Access Journals (Sweden)

    Manoel F. Gomes Filho

    2000-01-01

    Full Text Available Apresenta-se, neste trabalho, uma análise estatística baseada em correlações entre as temperaturas globais da superfície do mar (TSM e as descargas do Rio Piancó, no sertão da Paraíba, principal contribuinte do reservatório de Coremas, na região. Os coeficientes globais de correlação foram obtidos entre as temperaturas médias da superfície do mar, para os trimestres de novembro a janeiro e de fevereiro a abril, e as descargas do Rio Piancó no reservatório de Coremas, para cada mês de fevereiro até maio, que compreendem a estação chuvosa na bacia hidrográfica do reservatório. Os resultados mostram correlações significativas entre as TSM das regiões NINO1+2 e NINO3 no Oceano Pacífico. Na área do Atlântico não existe um padrão de correlações bem definido.This paper presents a statistical analysis based on the correlation between the Global Sea Surface Temperatures (SST and the discharge of Piancó river the principal contributor to the Coremas reservoir in the Paraíba State. The global correlation coefficients were obtained between the mean Sea Surface Temperatures (SST for the November to January and February to April trimesters and the volume of water discharged by the Piancó river in the Coremas reservoir for each of the individual months from February to May, the rainy season in the region of the reservoir. The results show the existence of a strong negative correlation between the SST's of the Nino1+2 and Nino3 regions of the Pacific Ocean. For the Atlantic area no well defined pattern of correlation was found.

  13. Variability in the Mean Latitude of the Atlantic ITCZ as Recorded in Cariaco Basin Sediments

    Science.gov (United States)

    Peterson, L. C.; Haug, G. H.; Lea, D. W.; Hughen, K. A.

    2003-12-01

    Climate variability in the tropical Atlantic is largely forced by changes in the strength and position of the Intertropical Convergence Zone (ITCZ). The Cariaco Basin, located on the northern margin of Venezuela, is sensitive to tropical Atlantic climate change and its sediments provide a record of past ITCZ behavior. Today, the Cariaco Basin has two distinct seasons that reflect the annual migration of the ITCZ. Between January-March, when the ITCZ lies south near the equator, northeasterly trade winds sit directly overhead Cariaco Basin and coastal upwelling and high surface productivity dominate. Beginning in June-July, as the ITCZ moves north to near the Venezuelan coast, local rainfall reaches a maximum and upwelling diminishes or disappears. The impact of ITCZ motion on local sea surface temperatures (SSTs), rainfall, primary production and Cariaco sediment properties is marked, with varved sediments preserved during anoxic intervals the result of the seasonal contrast between biogenic input during the upwelling season and detrital input from rivers during the wet season. Here we review data from Cariaco Basin and other localities which suggest a coherent climatological response in the tropical Atlantic triggered by a pattern of ITCZ migration that mimicks the seasonal cycle. During periods of cooler North Atlantic SSTs, on time-scales ranging from the Little Ice Age to the Younger Dryas to the cold stadials of the last glacial, evidence suggests a southward shift in the mean latitudinal position of the ITCZ. During warm interstadials and periods of Holocene and deglacial warmth, northward shifts in ITCZ position and its belt of convective rainfall are inferred from increased detrital delivery. The apparent synchronization of changes in Cariaco sediment properties with changes recorded in Greenland ice imply a tight teleconnection between the tropical and high latitudes of the North Atlantic. Whether the rapid shifts in ITCZ position reflect a response to

  14. Southwestern Power Administration annual site environmental report CY 1997

    International Nuclear Information System (INIS)

    1998-01-01

    This report provides a synopsis of Southwestern Power Administration's (Southwestern's) effectiveness in managing its operations in an environmentally responsible manner. In CY 1997, the Office of Environmental, Safety, and Health was reorganized and incorporated into the Division of Acquisition and Property. The Division of Acquisition, Property, and Environmental Management maintains responsibility for development, oversight, and implementation of environmental programs. Senior Management at Southwestern has taken actions to increase environmental awareness throughout the organization. During CY 1997, (Southwestern) was not involved in any known programs or activities that had adverse impacts on the environment. The 1997 Environmental Appraisal, a portion of Southwestern's Self-Assessment and Appraisal Program, indicated approximately 90% compliance with Southwestern's written environmental programs. Southwestern continued to function throughout CY 1997 in an operations and maintenance posture with minor substation projects

  15. Southwestern Power Administration site environmental report for calendar year 1993

    International Nuclear Information System (INIS)

    1994-01-01

    During CY 93, Southwestern was not involved in any programs that had a direct effect on the environment, involving endangered species, protection of wetlands, or increased electromagnetic radiation. Southwestern continued to function throughout the year in an operations and maintenance posture with minor substation projects. Southwestern received an environmental management audit by the Department of Energy's Office of Environmental Audit (EH-24), during CY 1992. The purpose of the audit was to give Southwestern, DOE headquarters, and the Secretary an indication of the status of Southwestern management's effectiveness in discharging its duties in an environmentally responsible manner. The audit identified 17 findings. An action plan was developed and remediation of the findings has been accomplished. Several strengths were identified during the audit with regard to the environmental programs at Southwestern. Most importantly, senior management at Southwestern has taken actions to increase environmental awareness throughout the organization which is evidenced by the creation of the Environmental, Safety, Health, and Security Office

  16. VALE BOI (ALGARVE, PORTUGAL AND THE SOLUTREAN IN SOUTHWESTERN IBERIA

    Directory of Open Access Journals (Sweden)

    João Cascalheira

    2013-09-01

    Full Text Available Located at the crossroads of two rather different ecological and cultural worlds (Mediterranean Spain and Portuguese Atlantic, the site of Vale Boi is a crucial element in understanding the economic and social traits of the communities that inhabited Southwestern Iberia during the Last Glacial Maximum (LGM. Combining an open-air with a rockshelter component, Vale Boi presents a lengthy Solutrean record starting with a Proto-Solutrean phase followed by a set of occupations in the 25 to 20.3 ka cal BP time-span. The very rich and well preserved assemblages proved that the site was treated, throughout, as a seasonal residential camp and although a striking combination of exogenous cultural traits has been identified, regional adaptive idiosyncrasies are quite evident. This paper focuses on the results of the lithics, fauna, beads and portable art analysis from Vale Boi, and their impact on the comprehension of the LGM ecodynamics in Southwestern Iberia.Localizado en el marco de dos contextos diferentes desde el punto de vista ecológico y cultural (el Mediterráneo español y el Atlántico portugués, el yacimiento de Vale Boi (Algarve, Portugal es un lugar fundamental para comprender la organización económica y social de las comunidades que habitaron el sudoeste de la Península Ibérica durante el Último Máximo Glacial (LGM. Situado en una zona en la que se combinan ocupaciones al aire libre y en abrigo, Vale Boi presenta un amplio registro solutrense que comienza con el el Proto-Solutrense y a la que le siguen un amplio número de ocupaciones entre el 25 y el 20,3 ka BP. El importante y bien preservado conjunto demuestra que este asentamiento funcionó como un campamento residencia estacional. Aunque han sido identificados diversos caracteres culturales de origen exógeno, son también evidentes los elementos adaptativos idiosincráticos. El presente artículo se centra en los resultados de los análisis del utillaje lítico, la fauna, las

  17. North Atlantic, ITCZ, and Monsoonal Climate Links

    Science.gov (United States)

    Haug, G. H.; Deplazes, G.; Peterson, L. C.; Brauer, A.; Mingram, J.; Dulski, P.; Sigman, D. M.

    2008-12-01

    Major element chemistry and color data from sediment cores in the anoxic Cariaco Basin off Venezuela record with (sub)annual resolution large and abrupt shifts in the hydrologic cycle of the tropical Atlantic during the last 80 ka. These data suggest a direct connection between the position of the ITCZ over northern South America, the strength of trade winds, and the temperature gradient to the high northern latitudes, ENSO, and monsoonal climate in Asia. The mechanisms behind these decadal-scale ITCZ-monsoon swings can be further explored at major climate transitions such as the onset of Younger Dryas cooling at ~12.7 ka, one of the most abrupt climate changes observed in ice core, lake and marine records in the North Atlantic realm and much of the Northern Hemisphere. Annually laminated sediments from ideally record the dynamics of abrupt climate changes since seasonal deposition immediately responds to climate and varve counts accurately estimate the time of change. We compare sub-annual geochemical data from a lake in Western Germany, which provides one of the best-dated records currently available for this climate transition, with the new the Cariaco Basin record and a new and higher resolution record from Lake Huguang Maar in China, and the Greenland ice core record. The Lake Meerfelder Maar record indicates an abrupt increase in storminess, occurring from one year to the next at 12,678 ka BP, coincident with other observed climate changes in the region. We interpret this shift of the wintertime winds to signify an abrupt change in the North Atlantic westerlies to a stronger and more zonal jet. The observed wind shift provides the atmospheric mechanism for the strong temporal link between North Atlantic overturning and European climate during the last deglaciation, tightly coupled to ITCZ migrations observed in the Cariaco Basin sediments, and a stronger east Asian Monsoon winter monsoon as seen in lake Huguang Maar, when cave stalagmite oxygen isotope data

  18. Tropical Soil Chemistry

    DEFF Research Database (Denmark)

    Borggaard, Ole K.

    and environmental protection. Tropical Soil Chemistry by Ole K. Borggaard provides an overview of the composition, occurrence, properties, processes, formation, and environmental vulnerability of various tropical soil types (using American Soil Taxonomy for classification). The processes and the external factors...... soil chemical issues are also presented to assess when, why, and how tropical soils differ from soils in other regions. This knowledge can help agricultural specialists in the tropics establish sustainable crop production. Readers are assumed to be familiar with basic chemistry, physics...

  19. Shallow-water Aplysina Nardo (Aplysinidae, Verongida, Demospongiae from the São Sebastião Channel and its environs (Tropical southwestern Atlantic, with the description of a new species and a literature review of other brazilian records of the genus

    Directory of Open Access Journals (Sweden)

    Ulisses dos Santos Pinheiro

    2001-07-01

    Full Text Available Two species of Aplysina Nardo, 1834 are described in this article, Aplysina caissara sp. n. and A. fulva (Pallas, 1766. Additionally, a possible third species was identified as A. aff. cauliformis. Collections were done in the São Sebastião Channel area as an ongoing effort to assess the poriferan biodiversity of the northern sector of the São Paulo State coastline. Specimens were collected by scuba diving, and descriptions of external morphology are based on the observation of populations alive, and on extensive underwater photography. A literature review of other brazilian records of Aplysina was undertaken, and an ammended species list is offered.

  20. Soil-atmosphere exchange of nitrous oxide, methane and carbon dioxide in a gradient of elevation in the coastal Brazilian Atlantic forest

    Science.gov (United States)

    E. Sousa Neto; J.B. Carmo; Michael Keller; S.C. Martins; L.F. Alves; S.A. Vieira; M.C. Piccolo; P. Camargo; H.T.Z. Couto; C.A. Joly; L.A. Martinelli

    2011-01-01

    Soils of tropical forests are important to the global budgets of greenhouse gases. The Brazilian Atlantic Forest is the second largest tropical moist forest area of South America, after the vast Amazonian domain. This study aimed to investigate the emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes along an altitudinal transect and the...

  1. Attractivity of omnivore, carnivore and herbivore mammalian dung to Scarabaeinae (Coleoptera, Scarabaeidae in a tropical Atlantic rainforest remnant Atratividade de Scarabaeinae (Coleoptera: Scarabaeidae por fezes de mamíferos onívoros, carnívoros e herbívoros em um remanescente de Floresta Tropical Atlântica

    Directory of Open Access Journals (Sweden)

    Bruno K. C. Filgueiras

    2009-01-01

    Full Text Available In this study, performed in a remnant of Brazilian Atlantic Forest, three types of dung from animals with distinct alimentary habits were utilized, in order to verify possible differences of attractivity of these dungs to the Scarabaeinae and the influence of seasonality in the attractivity. Three habitats were sampled: edge, clearing and forest core, each with 40 pitfall traps. A total of 2,137 beetles were collected from August 2005 to July 2006. Canthidium sp. 1 (43% and Dichotomius sericeus (41% were the most abundant species. From the total number of beetles collected, 80.5% were attracted to human dung, 11% to jaguar dung, 7.8% to waterbuck dung and 0.7% to the control. The species Canthidium sp.1, Canthidium sp. 2, Ateuchus sp., Canthon nigripenne, Canthonella sp. and D. sericeus came to all three bait types. Eight species were found in the baits with human dung, where Canthidium sp.1 (49% and D. sericeus (39% were the most common. A significant difference in attractiveness of the different baits was observed; the highest abundance found in traps baited with human dung (F = 36.59; g.l. = 3; p Nesse estudo, realizado em um remanescente de Floresta Atlântica Brasileira, três tipos de fezes de animais com distintos hábitos alimentares foram utilizados para verificar possíveis diferenças de atratividade dessas fezes por Scarabaeinae e a influência da sazonalidade nessa atratividade. Três habitats foram amostrados: borda, clareira e núcleo da floresta, cada um com 40 armadilhas de queda ("pitfall". Um total de 2137 besouros foi coletado de agosto de 2005 a julho de 2006. Canthidium sp. 1 (43% e Dichotomius sericeus (41% foram as espécies mais abundantes. Do número total de besouros coletados, 80,5% foram atraídos para fezes humanas, 11% para fezes de jaguar, 7,8% para fezes de cobo e 0,7% para o controle. As espécies Canthidium sp.1, Canthidium sp. 2, Ateuchus sp., Canthon nigripenne, Canthonella sp. e D. sericeus foram aos tr

  2. Defaunation affects carbon storage in tropical forests.

    Science.gov (United States)

    Bello, Carolina; Galetti, Mauro; Pizo, Marco A; Magnago, Luiz Fernando S; Rocha, Mariana F; Lima, Renato A F; Peres, Carlos A; Ovaskainen, Otso; Jordano, Pedro

    2015-12-01

    Carbon storage is widely acknowledged as one of the most valuable forest ecosystem services. Deforestation, logging, fragmentation, fire, and climate change have significant effects on tropical carbon stocks; however, an elusive and yet undetected decrease in carbon storage may be due to defaunation of large seed dispersers. Many large tropical trees with sizeable contributions to carbon stock rely on large vertebrates for seed dispersal and regeneration, however many of these frugivores are threatened by hunting, illegal trade, and habitat loss. We used a large data set on tree species composition and abundance, seed, fruit, and carbon-related traits, and plant-animal interactions to estimate the loss of carbon storage capacity of tropical forests in defaunated scenarios. By simulating the local extinction of trees that depend on large frugivores in 31 Atlantic Forest communities, we found that defaunation has the potential to significantly erode carbon storage even when only a small proportion of large-seeded trees are extirpated. Although intergovernmental policies to reduce carbon emissions and reforestation programs have been mostly focused on deforestation, our results demonstrate that defaunation, and the loss of key ecological interactions, also poses a serious risk for the maintenance of tropical forest carbon storage.

  3. Tropical Freshwater Biology

    African Journals Online (AJOL)

    Tropical Freshwater Biology promotes the publication of scientific contributions in the field of freshwater biology in the tropical and subtropical regions of the world. One issue is published annually but this number may be increased. Original research papers and short communications on any aspect of tropical freshwater ...

  4. Atlantic menhaden adult tagging study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Atlantic menhaden are a schooling forage fish species, which are subject to a large commercial purse seine fishery. Atlantic menhaden are harvested for reduction...

  5. Pliocene shallow water paleoceanography of the North Atlantic ocean based on marine ostracodes

    Science.gov (United States)

    Cronin, T. M.

    1991-01-01

    Middle Pliocene marine ostracodes from coastal and shelf deposits of North and Central America and Iceland were studied to reconstruct paleotemperatures of shelf waters bordering portions of the Western Boundary Current System (including the Gulf Loop Current, Florida Current, Gulf Stream and North Atlantic Drift). Factor analytic transfer functions provided Pliocene August and February bottom-water temperatures of eight regions from the tropics to the subfrigid. The results indicate: (1) meridional temperature gradients in the western North Atlantic were less steep during the Pliocene than either today or during Late Pleistocene Isotope Stage 5e; (2) tropical and subtropical shelf waters during the Middle Pliocene were as warm as, or slightly cooler than today; (3) slightly cooler water was on the outer shelf off the southeastern and mid-Atlantic coast of the U.S., possibly due to summer upwelling of Gulf Stream water; (4) the shelf north of Cape Hatteras, North Carolina may have been influenced by warm water incursions from the western edge of the Gulf Stream, especially in summer; (5) the northeast branch of the North Atlantic Drift brought warm water to northern Iceland between 4 and 3 Ma; evidence from the Iceland record indicates that cold East Greenland Current water did not affect coastal Iceland between 4 and 3 Ma; (6) Middle Pliocene North Atlantic circulation may have been intensified, transporting more heat from the tropics to the Arctic than it does today. ?? 1991.

  6. On some rare Oplophoridae (Caridea, Decapoda from the South Mid-Atlantic Ridge

    Directory of Open Access Journals (Sweden)

    Irene Cardoso

    2013-04-01

    Full Text Available The Mid-Atlantic Ridge (MAR divides the Atlantic Ocean longitudinally into two halves, each with a series of major basins delimited by secondary, more or less transverse ridges. Recent biological investigations in this area were carried out within the framework of the international project Mar-Eco (Patterns and Processes of the Ecosystems of the Mid-Atlantic Ridge. In 2009 (from October, 25 to November, 29 12 benthic sampling events were conducted on the R/V Akademik Ioffe, during the first oceanographic cruise of South Atlantic Mar-Eco. As a result we report some rare Oplophoridae species collected during the cruise. This family includes 73 species occurring strictly on the meso- and bathypelagic zones of the oceans. Five Oplophoridae species were sampled: Acanthephyra acanthitelsonis Bate, 1888; A. quadrispinosa Kemp, 1939; Heterogenys monnioti Crosnier, 1987; Hymenodora glacialis (Buchholz, 1874 and Kemphyra corallina (A. Milne-Edwards, 1883. Among these, H. monnioti and K. corallina are considered extremely rare, both with very few records. Of the sampled species, only A. quadrispinosa and H. glacialis were previously recorded to southwestern Atlantic, so the Oplophoridae fauna of the South MAR seems more related with the fauna from the eastern Atlantic and Indian oceans.

  7. Changes in North Atlantic nitrogen fixation controlled by ocean circulation.

    Science.gov (United States)

    Straub, Marietta; Sigman, Daniel M; Ren, Haojia; Martínez-García, Alfredo; Meckler, A Nele; Hain, Mathis P; Haug, Gerald H

    2013-09-12

    In the ocean, the chemical forms of nitrogen that are readily available for biological use (known collectively as 'fixed' nitrogen) fuel the global phytoplankton productivity that exports carbon to the deep ocean. Accordingly, variation in the oceanic fixed nitrogen reservoir has been proposed as a cause of glacial-interglacial changes in atmospheric carbon dioxide concentration. Marine nitrogen fixation, which produces most of the ocean's fixed nitrogen, is thought to be affected by multiple factors, including ocean temperature and the availability of iron and phosphorus. Here we reconstruct changes in North Atlantic nitrogen fixation over the past 160,000 years from the shell-bound nitrogen isotope ratio ((15)N/(14)N) of planktonic foraminifera in Caribbean Sea sediments. The observed changes cannot be explained by reconstructed changes in temperature, the supply of (iron-bearing) dust or water column denitrification. We identify a strong, roughly 23,000-year cycle in nitrogen fixation and suggest that it is a response to orbitally driven changes in equatorial Atlantic upwelling, which imports 'excess' phosphorus (phosphorus in stoichiometric excess of fixed nitrogen) into the tropical North Atlantic surface. In addition, we find that nitrogen fixation was reduced during glacial stages 6 and 4, when North Atlantic Deep Water had shoaled to become glacial North Atlantic intermediate water, which isolated the Atlantic thermocline from excess phosphorus-rich mid-depth waters that today enter from the Southern Ocean. Although modern studies have yielded diverse views of the controls on nitrogen fixation, our palaeobiogeochemical data suggest that excess phosphorus is the master variable in the North Atlantic Ocean and indicate that the variations in its supply over the most recent glacial cycle were dominated by the response of regional ocean circulation to the orbital cycles.

  8. Coral-based climate records from tropical South Atlantic

    DEFF Research Database (Denmark)

    Pereira, Natan S.; Sial, Alcides N.; Kikuchi, Ruy K.P.

    2015-01-01

    Coral skeletons contain records of past environmental conditions due to their long life span and well calibrated geochemical signatures. C and O isotope records of corals are especially interesting, because they can highlight multidecadal variability of local climate conditions beyond the instrum...

  9. Open ocean dead zones in the tropical North Atlantic Ocean

    Science.gov (United States)

    Karstensen, J.; Fiedler, B.; Schütte, F.; Brandt, P.; Körtzinger, A.; Fischer, G.; Zantopp, R.; Hahn, J.; Visbeck, M.; Wallace, D.

    2015-04-01

    Here we present first observations, from instrumentation installed on moorings and a float, of unexpectedly low (zones are created at shallow depth, just below the mixed layer, in the euphotic zone of cyclonic eddies and anticyclonic-modewater eddies. Both types of eddies are prone to high surface productivity. Net respiration rates for the eddies are found to be 3 to 5 times higher when compared with surrounding waters. Oxygen is lowest in the centre of the eddies, in a depth range where the swirl velocity, defining the transition between eddy and surroundings, has its maximum. It is assumed that the strong velocity at the outer rim of the eddies hampers the transport of properties across the eddies boundary and as such isolates their cores. This is supported by a remarkably stable hydrographic structure of the eddies core over periods of several months. The eddies propagate westward, at about 4 to 5 km day-1, from their generation region off the West African coast into the open ocean. High productivity and accompanying respiration, paired with sluggish exchange across the eddy boundary, create the "dead zone" inside the eddies, so far only reported for coastal areas or lakes. We observe a direct impact of the open ocean dead zones on the marine ecosystem as such that the diurnal vertical migration of zooplankton is suppressed inside the eddies.

  10. Application of the Marsupial Paradigm to Tropical Cyclone Formation from Northwestward-Propagating Disturbances

    Science.gov (United States)

    Wang, Zhuo; Dunkerton, Timothy J.; Montgomery, Michael T.

    2012-01-01

    A wave-tracking algorithm is developed for northwestward-propagating waves that, on occasion, play a role in tropical cyclogenesis over the western oceans. To obtain the Lagrangian flow structure, the frame of reference is translated obliquely at the same propagation speed with the precursor disturbance. Trajectory analysis suggests that streamlines in the obliquely translated frame of reference can be used to approximate flow trajectories. The algorithm was applied to Super Typhoon Nakri (2008), Tropical Cyclone Erika (2009), and a few other examples. Diagnoses of meteorological analyses and satellite-derived moisture and precipitation fields show that the marsupial framework for tropical cyclogenesis in tropical easterly waves is relevant also for northwestward-propagating disturbances as are commonly observed in the tropical western Atlantic, the Gulf of Mexico, and the western North Pacific. Finally, it is suggested that analysis of the global model data and satellite observations in the marsupial framework can provide useful guidance on early tropical cyclone advisories.

  11. Water Mass Variability at the Mid-Atlantic Ridge and in the Eastern North Atlantic

    Science.gov (United States)

    Köllner, Manuela; Klein, Birgit; Kieke, Dagmar; Klein, Holger; Roessler, Achim; Rhein, Monika

    2017-04-01

    The strong warming and salinification of the Eastern North Atlantic starting in the mid 1990s has been attributed to a westward contraction of the sub-polar gyre and stronger inflow of waters from the sub-tropical gyre. Temporal changes in the shape and strength of the two gyres have been related to the major mode of atmospheric variability in the Atlantic sector, the NAO. Hydrographic conditions along the Northwest European shelf are thus the result of different processes such as variations in transports, varying relative contributions of water masses from the two gyres and property trends in the source water masses. The North Atlantic Current (NAC) can be regarded as the southern border of the sub-polar gyre transporting water from the tropical regions northward. On its way towards the Mid Atlantic Ridge (MAR) the NAC has partly mixed with waters from the sub-polar gyre and crosses the MAR split into several branches. For the study we analyzed data of water mass variability and transport fluctuations from the RACE (Regional circulation and Global change) project (2012-2015) which provided time series of transports and hydrographic anomalies from moored instruments at the western flank of the MAR. The time depending positions of the NAC branches over the MAR were obtained from mooring time series and compared to sea surface velocities from altimeter data. The results show a high variability of NAC pathways over the MAR. Transition regimes with strong meandering and eddies could be observed as well as periods of strong NAC branches over the Fracture Zones affecting water mass exchange at all depth levels. A positive temperature trend at depths between 1000-2000 m was found at the Faraday Fracture Zone (FFZ). This warming trend was also detected by Argo floats crossing the MAR close to the FFZ region. During the second phase of RACE (RACE-II, 2016-2018) a mooring array across the eastern shelf break at Goban Spur was deployed to monitor the poleward Eastern Boundary

  12. Southwestern Institute of Physics annual report 2001

    International Nuclear Information System (INIS)

    2002-01-01

    In the year 2001, significant progresses in the engineering construction of the HL-2A tokamak were made at the Southwestern Institute of Physics (SWIP). At the same time, the research projects from Nuclear Energy Development Foundation, the National Defense Basic Research Foundation and the National Science Foundation of China were completely fulfilled. In addition 283 papers and reports were contributed, among them, 67 are included in the Annual Report

  13. Southwestern Power Administration Annual Report 2008

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-12-01

    Dear Secretary Chu, I am pleased to present the financial statements and operating data for Southwestern Power Administration (Southwestern) for Fiscal Year (FY) 2008. In FY 2008, Southwestern delivered over 7.3 billion kilowatt-hours of energy to its wholesale customers – nearly 31% more than average due to numerous record rainfall amounts in the southwest region. These record amounts produced revenues which exceeded the average annual revenue requirement by nearly $20 million and resulted in over $200 million in economic benefits to the region. Yet even as Southwestern exceeded its goals of marketing and delivering Federal hydroelectric power to our customers, we stayed focused on safety, security, and reliability. For example, we maintained our nearly 1,400 miles of high-voltage transmission lines, substations, and communications sites while achieving a Recordable Accident Frequency Rate of 0.0, a record that reflects Southwestern’s safety achievement of no recordable injuries for every 200,000 hours worked. We kept our rights-of-way secure from vegetation and other obstacles, work that not only supports our mission but also promotes reliability of the regional and National grid. We exceeded all North American Electric Reliability Corporation (NERC) Control Performance Standards (CPS- 1 and CPS-2), and maintained regulation and reserve obligations and reactive reserve margins to ensure the reliability of the bulk electric system, even during extended periods of restricted hydro operations due to unusually high project inflows. Finally, we continued our partnerships with the Department of Energy, the U.S. Army Corps of Engineers, our customers, and other Federal power stakeholders, partnerships that are vital to our continued success in marketing and delivering carbon-free, renewable, and domestically produced energy to our customers and to the Nation. Sincerely, Jon Worthington Administrator

  14. Discrete measurement of Carbon Dioxide, Hydrographic, and Chemical Data and surface underway measurements of partial pressure of CO2 during the R/V Meteor cruise 68/3 in the tropical Atlantic Ocean from 2006-07-12 to 2006-08-06 (NODC Accession 0109917)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0109917 includes chemical, discrete sample, physical and profile data collected from METEOR in the North Atlantic Ocean from 2006-07-12 to 2006-08-06...

  15. Quantifying Environmental Control on Tropical Cyclone Intensity Change

    Science.gov (United States)

    2010-08-01

    is smaller and confined primarily to the Gulf of Mexico, Carribean Sea, and east of the Lesser Antilles. In the WPAC, SSTs vary significantly...environmental and climatology and persistence characteristics of tropical cyclones (TCs) undergoing different intensity changes in the western North Pacific...WPAC) and North Atlantic (ATL) ocean basins. Using the cumulative distribution functions of 24-h intensity changes from the 2003–08 best-track data, four

  16. Physical trajectory profile data from glider SG610 deployed by Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2015-02-06 to 2015-04-27 (NCEI Accession 0137961)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  17. Physical trajectory profile data from glider SG630 deployed by US DOC; NOAA; OAR; Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2016-07-21 to 2016-11-10 (NCEI Accession 0157713)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  18. Physical trajectory profile data from glider SG609 deployed by US DOC; NOAA; OAR; Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2016-07-21 to 2016-11-10 (NCEI Accession 0157655)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  19. Profile chemical, physical and optical data collected aboard the SEWARD JOHNSON in the Caribbean Sea and North Atlantic Ocean from June 22, 2006 to July 24, 2006 (NODC Accession 0059071)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains hydrographic data collected during cruise SJ0609 in the tropical North Atlantic. Leg 1 of the cruise began in Ft. Pierce FL with a rapid...

  20. Physical and chemical data collected using bottle and BTs casts in the TOGA Area of Atlantic Ocean from NOAA Ship RESEARCHER and other platforms from 1974-06-25 to 1974-08-16 (NODC Accession 7700649)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data was collected from June 25, 1974 to August 16, 1974 using METEOR and other platforms as part of GARP (Global Atmospheric Research Program) Atlantic Tropical...

  1. Physical trajectory profile data from glider SG609 deployed by Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2015-07-15 to 2015-11-16 (NCEI Accession 0145655)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  2. Physical trajectory profile data from glider SG610 deployed by Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2014-07-15 to 2014-11-19 (NCEI Accession 0137960)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  3. Physical trajectory profile data from glider SG609 deployed by Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2015-02-06 to 2015-04-27 (NCEI Accession 0137927)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  4. Physical trajectory profile data from glider SG609 deployed by Atlantic Oceanographic and Meteorological Laboratory in the Caribbean Sea from 2016-03-10 to 2016-06-02 (NCEI Accession 0154495)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Seaglider data gathered as part of the Sustained Ocean Observations for Improving Atlantic Tropical Cyclone Intensity and Hurricane Seasonal Forecast project funded...

  5. Links between salinity variation in the Caribbean and North Atlantic thermohaline circulation.

    Science.gov (United States)

    Schmidt, Matthew W; Spero, Howard J; Lea, David W

    2004-03-11

    Variations in the strength of the North Atlantic Ocean thermohaline circulation have been linked to rapid climate changes during the last glacial cycle through oscillations in North Atlantic Deep Water formation and northward oceanic heat flux. The strength of the thermohaline circulation depends on the supply of warm, salty water to the North Atlantic, which, after losing heat to the atmosphere, produces the dense water masses that sink to great depths and circulate back south. Here we analyse two Caribbean Sea sediment cores, combining Mg/Ca palaeothermometry with measurements of oxygen isotopes in foraminiferal calcite in order to reconstruct tropical Atlantic surface salinity during the last glacial cycle. We find that Caribbean salinity oscillated between saltier conditions during the cold oxygen isotope stages 2, 4 and 6, and lower salinities during the warm stages 3 and 5, covarying with the strength of North Atlantic Deep Water formation. At the initiation of the Bølling/Allerød warm interval, Caribbean surface salinity decreased abruptly, suggesting that the advection of salty tropical waters into the North Atlantic amplified thermohaline circulation and contributed to high-latitude warming.

  6. Southwestern Power Administration Annual Report 2007

    Energy Technology Data Exchange (ETDEWEB)

    None

    2008-01-01

    “Renewable energy” isn’t just a catchphrase at Southwestern Power Administration (Southwestern). It describes the hydroelectric energy we market, and the energy that Southwestern’s employees bring to work every day, constantly challenging themselves to become more eff ective and effi cient in providing aff ordable, environmentally clean power to the American people. As Southwestern’s new Administrator, I have had the opportunity to view our operations from a fresh perspective, and I’m proud to share with you how a focus on continual improvement has been evident in accomplishments throughout the agency during fi scal year (FY) 2007. When the North American Electric Reliability Corporation (NERC) implemented new reliability standards, we met applicable implementation dates and exceeded NERC’s control performance standards throughout the year. When tasked with reducing the agency’s carbon footprint, we found ways to achieve an 8.7% reduction in energy intensity from last year without impacting our operational capabilities. And when faced with record-breaking infl ows into the reservoir projects from which we market power, we capitalized on the opportunity to provide customers with signifi cant quantities of supplemental energy. Our supplemental sales this year not only saved customers over $122 million, but increased Southwestern’s revenues -- a huge win-win for Southwestern’s ratepayers and the Nation’s taxpayers alike. Southwestern is proud of its role in protecting National and economic security by contributing to the diverse supply of domestically produced energy, operating and maintaining a safe and reliable transmission system, and ensuring good stewardship of our Nation’s water resources and environment. In FY 2007, Southwestern continued to repay all power costs to the American taxpayers by marketing and delivering approximately 5.6 billion kilowatthours of hydropower at cost-based rates to customers in our six-state region. This energy

  7. North Atlantic Oscillation: Concept and an Application.

    Science.gov (United States)

    Lamb, Peter J.; Peppler, Randy A.

    1987-10-01

    An outline of the concept of the North Atlantic Oscillation (NAO), along with some of its history is presented. This is followed by a brief presentation of the results and implications of an encouraging new application of the NAO to a regional climate problem-the interannual variation of Moroccan winter-semester precipitation. That precipitation is shown to be inversely related to the concurrent state of the NAO, and the relationship is relatively strong by the standards of recent research into the mechanisms of tropical and subtropical precipitation fluctuations. It is suggested that the NAO is of particular significance for the important issue of the long-range prediction of Moroccan (and probably also Spanish, Portuguese, and Algerian) winter precipitation, and that further research on this subject is warranted. Several specific recommendations in the latter regard are made.

  8. Progress toward seasonal prediction in the tropics

    Science.gov (United States)

    Knaff, John Albert

    Seasonal prediction in the tropics has been a slowly developing, yet very important topic in Atmospheric Science. Its slow evolution is a product of its history, a history determined by the rise and fall of empires, technological advances, and scientific opinions, but motivated ultimately by profit. In recent years, long-lead forecasting techniques in the tropics have again become popular. The occurrence of strong El Nino/Southern Oscillation (ENSO) events, droughts, floods, and intense landfalling tropical cyclones, has again prompted the meteorological community to use their knowledge to create useful seasonal forecasts for several regions of the tropics. Such forecasts will facilitate better management of natural resources, disaster preparation, and economic growth in these regions. Much has been learned about seasonal forecasting in the tropics in the last 125 years and much will be learned in the future, but progress is gained slowly by the piecing together of a great number of observation studies. This paper details but a few such studies. Within, the history of seasonal prediction in the tropics is discussed. Following this discussion the paper examines the physical implications of summertime sea level pressure anomalies (SLPAs) in the tropical Atlantic, the development of a simple regression model to predict June through September SLPAs in the Caribbean Sea region, and the development of a statistical ENSO prediction method which is based entirely on the optimal combination of persistence, trends of initial conditions and climatology. The future of seasonal forecasting in the tropics is bright. New technology along with improved datasets is allowing diagnostic and predictive studies that were once thought too exhaustive to be undertaken. This optimistic opinion must be tempered by this fields long history. Public and scientific opinion can rapidly change if seasonal prediction is not approached responsibly. This responsibility entails a rigorous definition

  9. The North Atlantic Oscillation as a driver of multidecadal variability of the AMOC, the AMO, and Northern Hemisphere climate

    Science.gov (United States)

    Delworth, T. L.; Zeng, F. J.; Yang, X.; Zhang, L.

    2017-12-01

    We use suites of simulations with coupled ocean-atmosphere models to show that multidecadal changes in the North Atlantic Oscillation (NAO) can drive multidecadal changes in the Atlantic Meridional Overturning Circulation (AMOC) and the Atlantic Multidecadal Oscillation (AMO), with associated hemispheric climatic impacts. These impacts include rapid changes in Arctic sea ice, hemispheric temperature, and modulation of Atlantic hurricane activity. We use models that incorporate either a fully dynamic ocean or a simple slab ocean to explore the role of ocean dynamics and ocean-atmosphere interactions. A positive phase of the NAO is associated with strengthened westerly winds over the North Atlantic. These winds extract more heat than normal from the subpolar ocean, thereby increasing upper ocean density, deepwater formation, and the strength of the AMOC and associated poleward ocean heat transport. This warming leads to a positive phase of the AMO. The enhanced oceanic heat transport extends to the Arctic where it causes a reduction of Arctic sea ice. Large-scale atmospheric warming reduces vertical wind shear in the tropical North Atlantic, creating an environment more favorable for tropical storms. We use models to further show that observed multidecadal variations of the NAO over the 20th and early 21st centuries may have led to multidecadal variations of simulated AMOC and the AMO. Specifically, negative NAO values from the late 1960s through the early 1980s led to a weakened AMOC/cold North Atlantic, whereas increasing NAO values from the late 1980s through the late 1990s increased the model AMOC and led to a positive (warm) phase of the AMO. The warm phase contributed to increases in tropical storm activity and decreases in Arctic sea ice after the mid 1990s. Ocean dynamics are essential for translating the observed NAO variations into ocean heat content variations for the extratropical North Atlantic, but appear less important in the tropical North Atlantic

  10. Atlantic hurricane surge response to geoengineering.

    Science.gov (United States)

    Moore, John C; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-11-10

    Devastating floods due to Atlantic hurricanes are relatively rare events. However, the frequency of the most intense storms is likely to increase with rises in sea surface temperatures. Geoengineering by stratospheric sulfate aerosol injection cools the tropics relative to the polar regions, including the hurricane Main Development Region in the Atlantic, suggesting that geoengineering may mitigate hurricanes. We examine this hypothesis using eight earth system model simulations of climate under the Geoengineering Model Intercomparison Project (GeoMIP) G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the Representative Concentration Pathway (RCP) 4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those temperature increases in the RCP4.5. However, sulfate injection would have to double (to nearly 10 teragrams of SO2 per year) between 2020 and 2070 to balance the RCP4.5, approximately the equivalent of a 1991 Pinatubo eruption every 2 y, with consequent implications for stratospheric ozone. We project changes in storm frequencies using a temperature-dependent generalized extreme value statistical model calibrated by historical storm surges and observed temperatures since 1923. The number of storm surge events as big as the one caused by the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this reduction is only marginally statistically significant. Nevertheless, when sea level rise differences in 2070 between the RCP4.5 and geoengineering are factored into coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5-y events and about halved for 50-y surges.

  11. Atlantic hurricane surge response to geoengineering

    Energy Technology Data Exchange (ETDEWEB)

    Moore, John C.; Grinsted, Aslak; Guo, Xiaoran; Yu, Xiaoyong; Jevrejeva, Svetlana; Rinke, Annette; Cui, Xuefeng; Kravitz, Ben; Lenton, Andrew; Watanabe, Shingo; Ji, Duoying

    2015-10-26

    Devastating Atlantic hurricanes are relatively rare events. However their intensity and frequency in a warming world may rapidly increase by a factor of 2-7 for each degree of increase in mean global temperature. Geoengineering by stratospheric sulphate aerosol injection cools the tropics relative to the polar regions, including the hurricane main development region in the Atlantic, suggesting that geoengineering may be an effective method of controlling hurricanes. We examine this hypothesis using 8 Earth System Model simulations of climate under the GeoMIP G3 and G4 schemes that use stratospheric aerosols to reduce the radiative forcing under the RCP4.5 scenario. Global mean temperature increases are greatly ameliorated by geoengineering, and tropical temperature increases are at most half of those in RCP4.5, but sulphate injection would have to double between 2020 and 2070 to balance RCP 4.5 to nearly 10 Tg SO2 yr-1, with consequent implications for damage to stratospheric ozone. We project changes in storm frequencies using a temperature-dependent Generalized Extreme Value statistical model calibrated by historical storm surges from 1923 and observed temperatures. The numbers of storm surge events as big as the one that caused the 2005 Katrina hurricane are reduced by about 50% compared with no geoengineering, but this is only marginally statistically significant. However, when sea level rise differences at 2070 between RCP4.5 and geoengineering are factored in to coastal flood risk, we find that expected flood levels are reduced by about 40 cm for 5 year events and perhaps halved for 50 year surges.

  12. Tropical Soil Chemistry

    DEFF Research Database (Denmark)

    Borggaard, Ole K.

    A new book that is particularly relevant as tropical countries experience increased pressure on land resources to improve agricultural production. To ensure sustainable land use, the potentials and limitations of different kinds of tropical soils must be known in relation to crop production...... and environmental protection. Tropical Soil Chemistry by Ole K. Borggaard provides an overview of the composition, occurrence, properties, processes, formation, and environmental vulnerability of various tropical soil types (using American Soil Taxonomy for classification). The processes and the external factors...... that affect soil processes are the same in tropical soils as in temperate region soils, but because of high temperature year round and occurrence in very stable landscapes, some (but not all) tropical soils possess special composition and properties. These features are highlighted in the book, and general...

  13. Bird diversity and conservation of Alto Balsas (Southwestern Puebla, Mexico

    Directory of Open Access Journals (Sweden)

    Jorge E Ramírez-Albores

    2007-03-01

    Full Text Available Knowledge of the composition of the bird community in Alto Balsas (southwestern Puebla, Central Mexico is needed for management programs aiming at protection and conservation of bird species and their habitats I studied sites with tropical deciduous forest. Data were obtained during 1666 hours of field work in 238 days from March 1998 to September 2000. Six permanent transect (3.5 km long and 100 m wide; 30 to 40 ha in each transect were used to determine species richness in the study sites. The Shannon-Wiener diversity index was calculated for each site and Sorensen’s index was used to assess similarity between sites. One-way analysis of variance was used to test for differences between sites in species richness and diversity values. A total of 128 species were recorded, Tepexco (n = 75, H´= 3.76 and Puente Márquez (n = 61, H´= 3.62 were the sites that showed the greatest specific richness and diversity. However, species richness and diversity seasonally patterns were similar among sites (ANOVA p > 0.05, with highest diversity during the rainy season. Most species were resident; 42 were migrants. The avifauna was represented by 30 species associated with tropical deciduous forest and 12 from open habitats or heavily altered habitats. Insectivores were the best represented trophic category, followed by carnivores and omnivores. Rev. Biol. Trop. 55 (1: 287-300. Epub 2007 March. 31.Este estudio describe la diversidad avifaunística en sitios del Alto Balsas (suroeste de Puebla en el Centro de México y examina la variación en la diversidad de las especies de aves. El estudio fue llevado a cabo en sitios con presencia de bosque tropical caducifolio. Los datos fueron obtenidos durante 1666 horas de trabajo de campo en 238 días de Marzo 1998 a Septiembre 2000. Se realizaron seis transectos permanentes (de 3.5 km de longitud y 100 m de ancho; de 30 a 40 ha en cada transecto para determinar la riqueza de especies en los sitios de estudio. Se

  14. Equatorial Atlantic interannual variability and its relation to dynamic and thermodynamic processes

    Directory of Open Access Journals (Sweden)

    J. Jouanno

    2017-11-01

    Full Text Available The contributions of the dynamic and thermodynamic forcing to the interannual variability of the equatorial Atlantic sea surface temperature (SST are investigated using a set of interannual regional simulations of the tropical Atlantic Ocean. The ocean model is forced with an interactive atmospheric boundary layer, avoiding damping toward prescribed air temperature as is usually the case in forced ocean models. The model successfully reproduces a large fraction (R2  =  0.55 of the observed interannual variability in the equatorial Atlantic. In agreement with leading theories, our results confirm that the interannual variations of the dynamical forcing largely contributes to this variability. We show that mean and seasonal upper ocean temperature biases, commonly found in fully coupled models, strongly favor an unrealistic thermodynamic control of the equatorial Atlantic interannual variability.

  15. Variability in north tropical atlantic over the last 20 000 years and holocene gulf stream activity; Variabilite au cours des derniers 20 000 ans de l'hydrologie de l'atlantique tropical nord et de l'activite du gulf stream a partir de la composition isotopique de l'oxygene et de la composition en elements trace des foraminferes planctoniques profonds

    Energy Technology Data Exchange (ETDEWEB)

    Cleroux, C

    2007-10-15

    Modern oceanographical studies shown that most of the ocean heat content in the North Atlantic Western Boundary Current region is stored in the upper 400 meters. To study past heat content and Gulf Stream activity, we performed coupled analyses of oxygen isotopic and trace elemental composition on several foraminifera species to reconstruct upper water column temperature and salinity. Calcification depths of Globorotalia inflata, Globorotalia truncatulinoides and Pulleniatina obliquiloculata have been constrain by correlating modern hydrographic data to oxygen isotopic measurement of North Atlantic core-top samples. We found that the three deep-dwelling foraminifera species have a preferred habitat at the base of the seasonal thermocline (Cleroux et al, 2007). The same set of North Atlantic core-tops has been used to define relationships between trace elemental compositions and temperature. We established calibrations between Mg/Ca ratio or Sr/Ca ratio and temperature for the three deep-dwelling foraminifera (Cleroux et al, submitted). We apply this strategy on the core MD99-2203 located off Cape Hatteras where the Gulf Stream separate from the United States coast. High-resolution surface reconstructions over the Holocene show low amplitude periodic temperature and salinity changes that could be related to NAO type mechanisms. Large hydrological changes in sub-surface reflect variations of Labrador current and Mode Water influences. Using recent studies on Mode Water formation and Gulf Stream heat advection, we interpret our results in term of ocean heat content and Gulf Stream activity. (author)

  16. An evaluation of management strategies for Atlantic tuna stocks

    Directory of Open Access Journals (Sweden)

    L. T. Kell

    2003-04-01

    Full Text Available International agreements for the International Commission for the Conservation of Atlantic Tunas (ICCAT convention area imply that Atlantic tuna stocks should be managed by strategies based on maximum sustainable yield (MSY; however, there is concern whether this will actually ensure sustainability with sufficiently high probability consistent with the principals of the precautionary approach. Therefore, the performance of MSY management strategies based on current assessment procedures was evaluated using a computer simulation framework. The framework includes the data collection, assessment, prediction, and management processes, as well as the implementation of management regulations. It therefore provides an integrated way to evaluate the relative importance of and the interactions between each component of the system with regard to the overall success of the management strategy. The study elucidates guidelines about assessment and management that are general enough to be applied to all tunas in the Atlantic Ocean. It does so by comparing different hypotheses about management and assessment for three stocks (North Atlantic albacore, Atlantic bigeye and East Atlantic skipjack, which are representative of the variety encountered (i.e. from data rich to poor and tropical to temperate waters in ICCAT stocks. Management performance was especially sensitive to the carrying capacity of the stock. The type of proxy used for MSY was more important to the success of the procedure than the frequency of assessment or the number of indices used in the assessment. Whilst the procedure was successful at achieving the management objectives for albacore, it was only partially successful for bigeye and was too conservative for skipjack.

  17. GPS radio occultation technique for measurement of the atmosphere above tropical cyclones

    DEFF Research Database (Denmark)

    Biondi, Riccardo; Neubert, Torsten; Syndergaard, Stig

    2009-01-01

    /lower stratosphere (UT/LS). The result is positive, suggesting that the bending angle of a GPS signal contains interesting information on the atmosphere around the tropopause. The presentation is focused on one particular Tropical Cyclone (TC), the hurricane Bertha, which formed in the Atlantic Basin during July...

  18. Atlantic Nessologies: Image, Territory, Value

    Directory of Open Access Journals (Sweden)

    Francisco-]. Hernández Adrián

    2006-01-01

    Full Text Available This essay addresses the emerging field of Atlantic Studies and questions the status of "the Atlantic" as an object of study. Rather than assuming a self-evident grid where Atlantic cultural phenomena oscillate between such poles as "centers and peripheries," or "the colonizer and the colonized," I consider a different formulation of the Atlantic. Taking as a starting point an analysis of a poem by Tomás Morales, a modernista poet from the Canary Islands, my essay outlines the notion of "Atlantic nessologies." Three parallel departures are offered from this analysis: image (or the realm of the imaginary; territory (or spatial and geopolitical inscriptions of the Atlantic in western space-time; and value (or those ethical and political dimensions that can be drawn from Atlantic specificities. Critical engagements with the Atlantic, my essay concludes, can be anchored in "nessological" readings in which neither local, singular perspectives contained in islands, nor wider, more panoramic views of the Atlantic, ought to escape critics. Instead, the work of engaging the Atlantic from multiple perspectives and locations should express itself as a field of critical/political strategies coordinated against perennial re-inscriptions of Eurocentric totality.

  19. The rare Chrysopidae (Neuroptera) of southwestern Europe

    Science.gov (United States)

    Canard, Michel; Letardi, Agostino; Thierry, Dominique

    2007-05-01

    Quantitative surveys of the chrysopid fauna from southwestern Europe, namely the Iberian and Italian peninsulas, France south of 46° N, and the west-Mediterranean Islands, were analysed. A total of 56 species of Chrysopidae were reported, of which three species were abundant. These, Chrysoperla carnea (Stephens, 1836) sensu lato, Dichochrysa prasina (Burmeister, 1839) and D. flavifrons (Brauer, 1850), comprised a large percentage of the specimens. For the rarer species, comments are made on their distributions, the enhanced geographic range of exotic ones, and on levels of endemism and stenotopy.

  20. Late Holocene climate variability in the southwestern Mediterranean region: an integrated marine and terrestrial geochemical approach

    Directory of Open Access Journals (Sweden)

    C. Martín-Puertas

    2010-12-01

    Full Text Available A combination of marine (Alboran Sea cores, ODP 976 and TTR 300 G and terrestrial (Zoñar Lake, Andalucia, Spain geochemical proxies provides a high-resolution reconstruction of climate variability and human influence in the southwestern Mediterranean region for the last 4000 years at inter-centennial resolution. Proxies respond to changes in precipitation rather than temperature alone. Our combined terrestrial and marine archive documents a succession of dry and wet periods coherent with the North Atlantic climate signal. A dry period occurred prior to 2.7 cal ka BP – synchronously to the global aridity crisis of the third-millennium BC – and during the Medieval Climate Anomaly (1.4–0.7 cal ka BP. Wetter conditions prevailed from 2.7 to 1.4 cal ka BP. Hydrological signatures during the Little Ice Age are highly variable but consistent with more humidity than the Medieval Climate Anomaly. Additionally, Pb anomalies in sediments at the end of the Bronze Age suggest anthropogenic pollution earlier than the Roman Empire development in the Iberian Peninsula. The Late Holocene climate evolution of the in the study area confirms the see-saw pattern between the eastern and western Mediterranean regions and the higher influence of the North Atlantic dynamics in the western Mediterranean.

  1. Elevational sensitivity in an Asian 'hotspot': moth diversity across elevational gradients in tropical, sub-tropical and sub-alpine China.

    Science.gov (United States)

    Ashton, L A; Nakamura, A; Burwell, C J; Tang, Y; Cao, M; Whitaker, T; Sun, Z; Huang, H; Kitching, R L

    2016-05-23

    South-western China is widely acknowledged as a biodiversity 'hotspot': there are high levels of diversity and endemism, and many environments are under significant anthropogenic threats not least climate warming. Here, we explore diversity and compare response patterns of moth assemblages among three elevational gradients established within different climatic bioregions - tropical rain forest, sub-tropical evergreen broad-leaved forest and sub-alpine coniferous forest in Yunnan Province, China. We hypothesised that tropical assemblages would be more elevationally stratified than temperate assemblages, and tropical species would be more elevationally restricted than those in the temperate zone. Contrary to our hypothesis, the moth fauna was more sensitive to elevational differences within the temperate transect, followed by sub-tropical and tropical transects. Moths in the cooler and more seasonal temperate sub-alpine gradient showed stronger elevation-decay beta diversity patterns, and more species were restricted to particular elevational ranges. Our study suggests that moth assemblages are under threat from future climate change and sub-alpine rather than tropical faunas may be the most sensitive to climate change. These results improve our understanding of China's biodiversity and can be used to monitor future changes to herbivore assemblages in a 'hotspot' of biodiversity.

  2. Elevational sensitivity in an Asian ‘hotspot’: moth diversity across elevational gradients in tropical, sub-tropical and sub-alpine China

    Science.gov (United States)

    Ashton, L. A.; Nakamura, A.; Burwell, C. J.; Tang, Y.; Cao, M.; Whitaker, T.; Sun, Z.; Huang, H.; Kitching, R. L.

    2016-01-01

    South-western China is widely acknowledged as a biodiversity ‘hotspot’: there are high levels of diversity and endemism, and many environments are under significant anthropogenic threats not least climate warming. Here, we explore diversity and compare response patterns of moth assemblages among three elevational gradients established within different climatic bioregions - tropical rain forest, sub-tropical evergreen broad-leaved forest and sub-alpine coniferous forest in Yunnan Province, China. We hypothesised that tropical assemblages would be more elevationally stratified than temperate assemblages, and tropical species would be more elevationally restricted than those in the temperate zone. Contrary to our hypothesis, the moth fauna was more sensitive to elevational differences within the temperate transect, followed by sub-tropical and tropical transects. Moths in the cooler and more seasonal temperate sub-alpine gradient showed stronger elevation-decay beta diversity patterns, and more species were restricted to particular elevational ranges. Our study suggests that moth assemblages are under threat from future climate change and sub-alpine rather than tropical faunas may be the most sensitive to climate change. These results improve our understanding of China’s biodiversity and can be used to monitor future changes to herbivore assemblages in a ‘hotspot’ of biodiversity. PMID:27211989

  3. 78 FR 59878 - Atlantic Highly Migratory Species; Commercial Atlantic Aggregated Large Coastal Shark (LCS...

    Science.gov (United States)

    2013-09-30

    ... Species; Commercial Atlantic Aggregated Large Coastal Shark (LCS), Atlantic Hammerhead Shark, Atlantic Blacknose Shark, and Atlantic Non-Blacknose Small Coastal Shark (SCS) Management Groups AGENCY: National... hammerhead sharks in the Atlantic region, and blacknose sharks and non-blacknose SCS in the Atlantic region...

  4. Tropical cyclones and climate change

    International Nuclear Information System (INIS)

    Andre, J.C.; Royer, J.F.; Chauvin, F.

    2008-01-01

    Results from observations and modelling studies, a number of which having been used to support the conclusions of the IPCC fourth assessment report, are presented. For the past and present-day (since 1970) periods, the increase of strong cyclonic activity over the North Atlantic Ocean appears to be in good correlation with increasing temperature of the ocean surface. For regions where observational data are of lesser quality, the increasing trend is less clear. In fact, assessing long-term changes is made difficult due to both the multi-decennial natural variability and the lesser coverage of observations before satellites were made available. Indirect observational data, such as those derived from quantitative estimations of damage caused by tropical cyclones, suffer from many artefacts and do not allow the resolving of the issue either. For the future, only numerical three-dimensional climate models can be used. They nevertheless run presently with too-large grid-sizes, so that their results are still not converging. Various simulations lead indeed to different results, and it is very often difficult to find the physical reasons for these differences. One concludes by indicating some ways through which numerical simulations could be improved, leading to a decrease of uncertainties affecting the prediction of cyclonic activity over the next decades. (authors)

  5. Diversity and distribution of whiteflies in south-western Nigeria ...

    African Journals Online (AJOL)

    Whiteflies (Aleyrodidae) are major pests of crops in southwestern Nigeria, yet there is scanty information on diversity and distribution of these economic species. Therefore, a study of diversity and distribution of whitefly fauna was carried out in southwestern Nigeria in wet and dry seasons, between May 2007 and June 2012.

  6. North Atlantic warming: patterns of long-term trend and multidecadal variability

    Energy Technology Data Exchange (ETDEWEB)

    Polyakov, Igor V.; Alexeev, Vladimir A.; Zhang, Xiangdong [University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK (United States); Bhatt, Uma S. [University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK (United States); Polyakova, Evgenia I. [Stanford University, Department of Geological and Environmental Studies, Stanford, CA (United States)

    2010-02-15

    Climate fluctuations in the North Atlantic Ocean have wide-spread implications for Europe, Africa, and the Americas. This study assesses the relative contribution of the long-term trend and variability of North Atlantic warming using EOF analysis of deep-ocean and near-surface observations. Our analysis demonstrates that the recent warming over the North Atlantic is linked to both long-term (including anthropogenic and natural) climate change and multidecadal variability (MDV, {proportional_to}50-80 years). Our results suggest a general warming trend of 0.031 {+-} 0.006 C/decade in the upper 2,000 m North Atlantic over the last 80 years of the twentieth century, although during this time there are periods in which short-term trends were strongly amplified by MDV. For example, MDV accounts for {proportional_to}60% of North Atlantic warming since 1970. The single-sign basin-scale pattern of MDV with prolonged periods of warming (cooling) in the upper ocean layer and opposite tendency in the lower layer is evident from observations. This pattern is associated with a slowdown (enhancement) of the North Atlantic thermohaline overturning circulation during negative (positive) MDV phases. In contrast, the long-term trend exhibits warming in tropical and mid-latitude North Atlantic and a pattern of cooling in regions associated with major northward heat transports, consistent with a slowdown of the North Atlantic circulation as evident from observations and confirmed by selected modeling results. This localized cooling has been masked in recent decades by warming during the positive phase of MDV. Finally, since the North Atlantic Ocean plays a crucial role in establishing and regulating the global thermohaline circulation, the multidecadal fluctuations discussed here should be considered when assessing long-term climate change and variability, both in the North Atlantic and at global scales. (orig.)

  7. Economically important species dominate aboveground carbon storage in forests of southwestern Amazonia

    Directory of Open Access Journals (Sweden)

    N. Galia Selaya

    2017-06-01

    Full Text Available Tree species in tropical forests provide economically important goods and ecosystem services. In submontane forests of southwestern Amazonia, we investigated the degree to which tree species important for subsistence and trade contribute to aboveground carbon storage (AGC. We used 41 1-hectare plots to determine the species abundance, basal area, and AGC of stems > 10 cm diameter at breast height (dbh. Economically important taxa were classified using ethnobotanical studies and according to their stem density. These taxa (n = 263 accounted for 45% of total stems, 53% of total basal area, and 56% of total AGC, significantly more than taxa with minor or unknown uses (Welch test at p 40 cm and few stems in regeneration classes of dbh < 10 to 20 cm (e.g., Bertholletia excelsa, Cariniana spp., Cedrelinga spp., Ceiba spp., Dipteryx spp., whereas dominant Tetragastris spp., and Pseudolmedia spp. had most stems in low diameter classes and a median diameter of < 30 cm. Bertholletia excelsa, with 1.5 stems per hectare, showed the highest basal area of any species and accounted for 9% of AGC (11 Mg/ha, twice that of the second-ranking species. Our study shows that economic importance and carbon stocks in trees are closely linked in southwestern Amazonia. Unplanned harvests can disrupt synergistic dual roles altering carbon stocks temporally or permanently. Precautionary measures based on species ecology, demography, and regeneration traits should be at the forefront of REDD+ to reconcile maximum harvesting limits, biodiversity conservation, and sustainable forest management.

  8. The Distribution of Dissolved Iron in the West Atlantic Ocean

    Science.gov (United States)

    Rijkenberg, Micha J. A.; Middag, Rob; Laan, Patrick; Gerringa, Loes J. A.; van Aken, Hendrik M.; Schoemann, Véronique; de Jong, Jeroen T. M.; de Baar, Hein J. W.

    2014-01-01

    Iron (Fe) is an essential trace element for marine life. Extremely low Fe concentrations limit primary production and nitrogen fixation in large parts of the oceans and consequently influence ocean ecosystem functioning. The importance of Fe for ocean ecosystems makes Fe one of the core chemical trace elements in the international GEOTRACES program. Despite the recognized importance of Fe, our present knowledge of its supply and biogeochemical cycle has been limited by mostly fragmentary datasets. Here, we present highly accurate dissolved Fe (DFe) values measured at an unprecedented high intensity (1407 samples) along the longest full ocean depth transect (17500 kilometers) covering the entire western Atlantic Ocean. DFe measurements along this transect unveiled details about the supply and cycling of Fe. External sources of Fe identified included off-shelf and river supply, hydrothermal vents and aeolian dust. Nevertheless, vertical processes such as the recycling of Fe resulting from the remineralization of sinking organic matter and the removal of Fe by scavenging still dominated the distribution of DFe. In the northern West Atlantic Ocean, Fe recycling and lateral transport from the eastern tropical North Atlantic Oxygen Minimum Zone (OMZ) dominated the DFe-distribution. Finally, our measurements showed that the North Atlantic Deep Water (NADW), the major driver of the so-called ocean conveyor belt, contains excess DFe relative to phosphate after full biological utilization and is therefore an important source of Fe for biological production in the global ocean. PMID:24978190

  9. Development of the Hatton-Rockall Basin, North-East Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, J.W.F. [British Geological Survey, Edinburgh (United Kingdom)

    2002-02-01

    Magnetic anomaly and Bouguer gravity anomaly maps have been prepared over the Hatton-Rockall Basin in the North-East Atlantic. A qualitative interpretation of these maps is presented. Two cross-sectional models have been constructed along lines perpendicular to the axis of the basin. The north-eastern part of the Hatton-Rockall Basin is characterised by circular intrusions and has evolved differently from the southwestern part, which is characterised by linear intrusions that reach the base of the sedimentary sequence. It is proposed that the two parts of the Basin evolved initially along similar lines, and that the southwestern part of the Basin evolved further with a period of extension at the same time as extension between Endymion Spur and Hatton Bank. (author)

  10. Impacts of SST anomalies on the North Atlantic atmospheric circulation: a case study for the northern winter 1995/1996

    Energy Technology Data Exchange (ETDEWEB)

    Losada, T.; Rodriguez-Fonseca, B. [Universidad Complutense de Madrid, Departmento de Geofisica y Meteorologia, Madrid (Spain); Mechoso, C.R.; Ma, H.Y. [University of California Los Angeles, Department of Atmospheric and Oceanic Sciences, Los Angeles, CA (United States)

    2007-12-15

    The present paper selects the northern winter of December 1995-February 1996 for a case study on the impact of sea surface temperature (SST) anomalies on the atmospheric circulation over the North Atlantic and Western Europe. In the Atlantic, the selected winter was characterized by positive SST anomalies over the northern subtropics and east of Newfoundland, and negative anomalies along the US coast. A weak La Nina event developed in the Pacific. The North Atlantic Oscillation (NAO) index was low, precipitation over the Iberian Peninsula and northern Africa was anomalously high, and precipitation over northern Europe was anomalously low. The method of study consists of assessing the sensitivity of ensemble simulations by the UCLA atmospheric general circulation model (UCLA AGCM) to SST anomalies from the observation, which are prescribed either in the World Oceans, the Atlantic Ocean only, or the subtropical North Atlantic only. The results obtained are compared with a control run that uses global, time-varying climatological SST. The ensemble simulations with global and Atlantic-only SST anomalies both produce results that resemble the observations over the North Atlantic and Western Europe. It is suggested that the anomalous behavior of the atmosphere in the selected winter over those regions, therefore, was primarily determined by conditions within the Atlantic basin. The simulated fields in the tropical North Atlantic show anomalous upward motion and lower (upper) level convergence (divergence) in the atmosphere overlying the positive SST anomalies. Consistently, the subtropical jet intensifies and its core moves equatorward, and precipitation increases over northern Africa and southern Europe. The results also suggest that the SST anomalies in the tropical North Atlantic only do not suffice to produce the atmospheric anomalies observed in the basin during the selected winter. The extratropical SST anomalies would provide a key contribution through increased

  11. Magnetic characterization of Holocene sedimentation in the South Atlantic

    Science.gov (United States)

    Schmidt, Andrea M.; von Dobeneck, Tilo; Bleil, Ulrich

    1999-08-01

    Surface sediment samples representative for the tropical and subtropical South Atlantic (15°N to 40°S) were investigated by isothermal magnetic methods to delineate magnetic mineral distribution patterns and to identify their predominant Holocene climatic and oceanographic controls. Individual parameters reveal distinct, yet frequently overlapping, regional sedimentation characteristics. A probabilistic ("fuzzy c-means") cluster analysis was applied to five concentration independent magnetic properties assessing magnetite to hematite ratios and diagnostic of bulk and fine-particle magnetite grain size and coercivity spectra. The resultant 10 cluster structures establish an oceanwide magnetic sediment classification scheme tracing the major terrigenous eolian and fluvial fluxes, authigenic biogenic magnetite accumulation in high-productivity areas, transport by ocean current systems, and effects of bottom water velocity on depositional regimes. Distinct dissimilarities in magnetic mineral inventories between the eastern and western basins of the South Atlantic reflect prominent contrasts of both oceanic and continental influences.

  12. The Atlantic Multidecadal Oscillation without a role for ocean circulation.

    Science.gov (United States)

    Clement, Amy; Bellomo, Katinka; Murphy, Lisa N; Cane, Mark A; Mauritsen, Thorsten; Rädel, Gaby; Stevens, Bjorn

    2015-10-16

    The Atlantic Multidecadal Oscillation (AMO) is a major mode of climate variability with important societal impacts. Most previous explanations identify the driver of the AMO as the ocean circulation, specifically the Atlantic Meridional Overturning Circulation (AMOC). Here we show that the main features of the observed AMO are reproduced in models where the ocean heat transport is prescribed and thus cannot be the driver. Allowing the ocean circulation to interact with the atmosphere does not significantly alter the characteristics of the AMO in the current generation of climate models. These results suggest that the AMO is the response to stochastic forcing from the mid-latitude atmospheric circulation, with thermal coupling playing a role in the tropics. In this view, the AMOC and other ocean circulation changes would be largely a response to, not a cause of, the AMO. Copyright © 2015, American Association for the Advancement of Science.

  13. Tropical Cyclone Propagation

    National Research Council Canada - National Science Library

    Gray, William

    1994-01-01

    This paper discusses the question of tropical cyclone propagation or why the average tropical cyclone moves 1-2 m/s faster and usually 10-20 deg to the left of its surrounding (or 5-7 deg radius) deep layer (850-300 mb) steering current...

  14. Tropical Diabetic Hand Syndrome

    African Journals Online (AJOL)

    [2,3] Tropical diabetic hand syndrome is a terminology used to describe a specific acute symptom complex found in diabetic patients in the tropics.[1-4] The syndrome comprises can rapidly progress to synergistic gangrene (Meleney's gangrene), affecting the entire limb and extending to the superficial fascia that can result in ...

  15. Archives: Tropical Freshwater Biology

    African Journals Online (AJOL)

    Items 1 - 23 of 23 ... Archives: Tropical Freshwater Biology. Journal Home > Archives: Tropical Freshwater Biology. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 23 of 23 Items ...

  16. Archives: Tropical Veterinarian

    African Journals Online (AJOL)

    Items 1 - 32 of 32 ... Archives: Tropical Veterinarian. Journal Home > Archives: Tropical Veterinarian. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 32 of 32 Items. 2017. Vol 35 ...

  17. Tropical Veterinarian: Editorial Policies

    African Journals Online (AJOL)

    TROPICAL VETERINARIAN is an international journal devoted to all aspects of veterinary science as practiced in the tropics, including livestock production and management, animal disease (domestic and wild), various aspects of preventive medicine and public health and basic and applied research in these areas.

  18. Tropical Veterinarian: Submissions

    African Journals Online (AJOL)

    Author Guidelines. 2012 Author Guidelines: Instructions to Authors: TROPICAL VETERINARIAN welcomes original work on all aspects of veterinary science as practiced in the Tropics, including livestock production and management, animal disease (domestic and wild), various aspects of preventive medicine and public ...

  19. Computing Tropical Varieties

    DEFF Research Database (Denmark)

    Speyer, D.; Jensen, Anders Nedergaard; Bogart, T.

    2005-01-01

    The tropical variety of a d-dimensional prime ideal in a polynomial ring with complex coefficients is a pure d-dimensional polyhedral fan. This fan is shown to be connected in codimension one. We present algorithmic tools for computing the tropical variety, and we discuss our implementation...

  20. Introduction to tropical geometry

    CERN Document Server

    Maclagan, Diane

    2015-01-01

    Tropical geometry is a combinatorial shadow of algebraic geometry, offering new polyhedral tools to compute invariants of algebraic varieties. It is based on tropical algebra, where the sum of two numbers is their minimum and the product is their sum. This turns polynomials into piecewise-linear functions, and their zero sets into polyhedral complexes. These tropical varieties retain a surprising amount of information about their classical counterparts. Tropical geometry is a young subject that has undergone a rapid development since the beginning of the 21st century. While establishing itself as an area in its own right, deep connections have been made to many branches of pure and applied mathematics. This book offers a self-contained introduction to tropical geometry, suitable as a course text for beginning graduate students. Proofs are provided for the main results, such as the Fundamental Theorem and the Structure Theorem. Numerous examples and explicit computations illustrate the main concepts. Each of t...

  1. A century of Amazon burning driven by Atlantic climate

    Science.gov (United States)

    Makou, M.; Thompson, L. G.; Davis, M. E.; Eglinton, T. I.

    2011-12-01

    Very little is known about annual burning trends in the Amazon Basin prior to remote sensing of fires beginning in the late 1970's. Fires reduce Amazon forest biomass and species richness, release pollutant aerosols, and impact the carbon cycle, compelling further investigation of fire-climate dynamics. We measured organic compounds derived from vegetation burning in ice core samples from the Quelccaya Ice Cap in Peru at better than annual resolution to reconstruct wet and dry season burning throughout the Twentieth Century. Variations in the abundance of methyl hexadecanoate, which is produced by thermal alteration of vascular plant alkanoic acids, were used as a proxy for past fire activity. Concentrations of this compound in Quelccaya ice varied strongly on seasonal, interannual, and decadal time scales over the last 100 years, with high-amplitude dry season variability and muted, decadal-scale changes in wet season fire activity. Decade-long periods of repeatedly enhanced burning occurred during the 1930's and 1960's when dry season precipitation was perpetually reduced, as evidenced by low stages of the Rio Negro. These decadal trends suggest that changes in dry season precipitation drive fire activity in the western Amazon and highlight the potential of Amazon forests to undergo repeated strong burning. Fires occurred during years when sea surface temperatures (SSTs) in the north tropical Atlantic were elevated and the north-south tropical Atlantic SST gradient was enhanced; this SST pattern likely displaced the intertropical convergence zone northward, driving subsidence and drought in the western and southern Amazon basin. Thus, our novel ice core record suggests that Amazon forest fire activity during the Twentieth Century was driven primarily by Atlantic climate processes, and future forest health will depend heavily on the evolution of tropical climate.

  2. Assessment of surf zone environmental variables in a southwestern Atlantic sandy beach (Monte Hermoso, Argentina).

    Science.gov (United States)

    Menéndez, M Clara; Fernández Severini, Melisa D; Buzzi, Natalia S; Piccolo, M Cintia; Perillo, Gerardo M E

    2016-08-01

    The aim of this study was to investigate the temporal dynamics (monthly/tidal) of water temperature, salinity, chlorophyll-a (chlo-a), suspended particulate matter (SPM), particulate organic carbon (POC), and dissolved nutrients in the surf zone of Monte Hermoso sandy beach, Argentina. We also aimed to understand the underlying mechanisms responsible for the observed variability. Sampling was carried out approximately monthly (September 2009-November 2010), and all samples were collected in a fixed station during high and low tide. Water temperature showed a clear seasonal variability (July: 9 °C-December: 26.5 °C) and a thermal amplitude of 17.5 °C. Salinity ranged from 33 to 37, without a pronounced seasonality. SPM (10-223 mg L(-1)) and POC concentrations (399-6445 mg C m(-3)) were high in surf zone waters. Chlo-a (0.05-9.16 μg L(-1)) was low and did not evidence the occurrence of surf diatom accumulations. Dissolved nutrient concentration was quite fluctuating. None of the variables seemed to be affected by tidal stage. The results showed how fluctuating the physico-chemical and biological variables can be in this particular system. The observed variability can be related with local beach conditions but also with regional processes. The study area is highly influenced by a neighbor estuary and as a consequence, could be vulnerable to their seasonal and inter-annual dynamics. All of these characteristics must be considered for further studies and planning of the uses of natural resources and should be taken into account in any environmental monitoring program conducted in a similar beach system.

  3. Female reproductive cycle of the Southwestern Atlantic estuarine crab Chasmagnathus granulatus (Brachyura, Grapsoidea, Varunidae

    Directory of Open Access Journals (Sweden)

    Romina B. Ituarte

    2004-03-01

    Full Text Available The female reproductive biology of a Chasmagnathus granulatus population inhabiting the area near the mouth of Mar Chiquita coastal lagoon, Argentina, was studied. An increase in air temperature during the spring is related to the start of the breeding period, when well defined egg-laying and hatching pulses were observed. Hatching is synchronic during the whole summer but the egg production was not, probably due to the gradual incorporation of young females to the reproductive population. Neither egg-laying nor larval release showed a clear relation to moon phase or tidal cycles, suggesting that reproduction is not rigidly programmed in this unpredictable habitat. Females moult at the beginning of autumn, after releasing the last larvae. However, a new cohort of ovocytes, which was in primary vitellogenesis before moulting, completed the secondary ovogenesis after moulting. Consequently, ovaries remained fully developed throughout the winter.

  4. Spawn in two deep-sea volute gastropods (Neogastropoda: Volutidae) from southwestern Atlantic waters

    Science.gov (United States)

    Penchaszadeh, Pablo E.; Teso, Valeria; Pastorino, Guido

    2017-12-01

    The gastropods Odontocymbiola pescalia and Provocator corderoi and their egg capsules were collected by the R/V Puerto Deseado from the Mar del Plata Submarine Canyon ( 37°53‧S, at depths of 291-1404 m) and from Burdwood Bank ( 54°27‧S, 128-785 m). Odontocymbiola pescalia egg capsules measured 15.67 ± 3.38 mm in diameter. They were subspherical in shape with an external calcareous layer. Each egg capsule contained 3-5 embryos and white material as extra embryonic food. Embryos grew to a size of up to 9.3 ± 1.1 mm in mean shell length before hatching as crawling juveniles. The spawn of P. corderoi consisted of a single dome shaped egg capsule of 14.17 ± 1.5 mm in diameter, attached to hard substrata by a basal membrane with a rounded outline. A curved semilunar furrow (seam) on one side of the capsules was always present. The number of embryos per capsule was 2-6. Embryos hatched as crawling juveniles with a shell length of 5.9 ± 0.6 mm. The size and number of whorls in the hatchling shell suggested a slow rate of development, akin to many other deep-sea invertebrates. The egg capsules and reproductive development strategies of both species were compared with those from other congeneric representatives.

  5. Distribution of anisakid nematodes parasitizing rajiform skates under commercial exploitation in the Southwestern Atlantic.

    Science.gov (United States)

    Irigoitia, Manuel Marcial; Braicovich, Paola Elizabeth; Lanfranchi, Ana Laura; Farber, Marisa Diana; Timi, Juan Tomás

    2018-02-21

    In order to evaluate the infestation by anisakids present in elasmobranchs and their distribution in the Argentine Sea, this study was carried at a regional scale with the following aims: 1) to identify those anisakid species present in skates under exploitation; 2) to characterize quantitatively these infestations and 3) to determine those factors driving the variability in parasite burdens across skate species. A total of 351 skates, belonging to 3 species (218 Sympterygia bonapartii, 86 Zearaja chilensis and 47 Atlantoraja castelnaui) and from different localities of the Argentine Sea were examined for anisakids. Parasites were found in the stomach wall at high prevalence in some samples. Based on morphology and mtDNA cox2 sequences analyses (from 24 larval worms), specimens were identified as Anisakis berlandi, A. pegreffii and Pseudoterranova cattani; the last two known as potentially pathogenic for humans. Differential distribution patterns were observed across parasite and hosts species. In general, fish caught in southern and deeper waters exhibited higher loads of Anisakis spp., whereas infestation levels by P. cattani increase in larger skates. Taking into account that the mere presence of worms or their antigens in fish meat can provoke allergic responses, information on distribution of parasites and their variability is essential for the implementation of food safety practices. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. A new species of Cheiriphotis (Amphipoda, Corophiidae from the southwestern Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Jesser F. Souza-Filho

    Full Text Available A new species, Cheiriphotis petronioi sp. nov., is described from the Brazilian coast. This species is recognizable amongst its congeners by the carpus of adult male gnathopod 2 not fused with propodus and the palm acute and uropod 1 of adult males without a group of apical setae between rami. Specimens studied herein were collected between 23º and 34ºS (Brazil - São Paulo and Rio Grande do Sul from 16 to 38 m depth. An updated key to all species of the genus is provided.

  7. Local ecological knowledge and scientific data reveal overexploitation by multigear artisanal fisheries in the southwestern Atlantic.

    Directory of Open Access Journals (Sweden)

    Mariana G Bender

    Full Text Available In the last decades, a number of studies based on historical records revealed the diversity loss in the oceans and human-induced changes to marine ecosystems. These studies have improved our understanding of the human impacts in the oceans. They also drew attention to the shifting baseline syndrome and the importance of assessing appropriate sources of data in order to build the most reliable environmental baseline. Here we amassed information from artisanal fishermen's local ecological knowledge, fisheries landing data and underwater visual census to assess the decline of fish species in Southeastern Brazil. Interviews with 214 fishermen from line, beach seine and spearfishing revealed a sharp decline in abundance of the bluefish Pomatomus saltatrix, the groupers Epinephelus marginatus, Mycteroperca acutirostris, M. bonaci and M. microlepis, and large parrotfishes in the past six decades. Fisheries landing data from a 16-year period support the decline of bluefish as pointed by fishermen's local knowledge, while underwater visual census campaigns show reductions in groupers' abundance and a sharp population decline of the Brazilian endemic parrotfish Scarus trispinosus. Despite the marked decline of these fisheries, younger and less experienced fishermen recognized fewer species as overexploited and fishing sites as depleted than older and more experienced fishermen, indicating the occurrence of the shifting baseline syndrome. Here we show both the decline of multigear fisheries catches - combining anecdotal and scientific data - as well as changes in environmental perceptions over generations of fishermen. Managing ocean resources requires looking into the past, and into traditional knowledge, bringing historical baselines to the present and improving public awareness.

  8. Atlantic Oceanographic and Meteorological Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Atlantic Oceanographic and Meteorological Laboratory conducts research to understand the physical, chemical, and biological characteristics and processes of the...

  9. On tropical cyclone frequency and the warm pool area

    Directory of Open Access Journals (Sweden)

    R. E. Benestad

    2009-04-01

    Full Text Available The proposition that the rate of tropical cyclogenesis increases with the size of the "warm pool" is tested by comparing the seasonal variation of the warm pool area with the seasonality of the number of tropical cyclones. An analysis based on empirical data from the Northern Hemisphere is presented, where the warm pool associated with tropical cyclone activity is defined as the area, A, enclosed by the 26.5°C SST isotherm. Similar analysis was applied to the temperature weighted area AT with similar results.

    An intriguing non-linear relationship of high statistical significance was found between the temperature weighted area in the North Atlantic and the North-West Pacific on the one hand and the number of cyclones, N, in the same ocean basin on the other, but this pattern was not found over the North Indian Ocean. A simple statistical model was developed, based on the historical relationship between N and A. The simple model was then validated against independent inter-annual variations in the seasonal cyclone counts in the North Atlantic, but the correlation was not statistically significant in the North-West Pacific. No correlation, however, was found between N and A in the North Indian Ocean.

    A non-linear relationship between the cyclone number and temperature weighted area may in some ocean basins explain both why there has not been any linear trend in the number of cyclones over time as well as the recent upturn in the number of Atlantic hurricanes. The results also suggest that the notion of the number of tropical cyclones being insensitive to the area A is a misconception.

  10. Recent interdecadal shift in the relationship between Northeast China's winter precipitation and the North Atlantic and Indian Oceans

    Science.gov (United States)

    Tingting, Han; Shengping, He; Xin, Hao; Huijun, Wang

    2018-02-01

    This study documents an interdecadal change in the interannual relationship between Northeast China's winter precipitation (NECWP) and the sea surface temperature (SST) in the North Atlantic and Indian Oceans in the 1990s. It is revealed that the NECWP shows a significant simultaneous correlation with the SST anomalies in the North Atlantic (SST_Atlantic)/tropical Indian Ocean (SST_Indian) during 1996-2013/1961-1990. Generally, the NECWP anomaly is concurrent with apparent Eurasian wave pattern during 1961-1990 whereas anomalous Okhotsk high and East Asia trough during 1996-2013. It is found that, before the 1990s, the warming SST anomalies in the tropical Indian Ocean could stimulate the Eurasian wave pattern via inducing significant anomalous upper-level convergence over the northern Europe, which tends to favor a positive NECWP anomaly. During 1996-2013, the SST_Indian-NECWP connection is disrupted. Instead, the North Atlantic tri-polar SST anomaly pattern exerts a dominant impact on the NECWP through triggering a stationary Rossby wave that originates from the North Atlantic and propagates eastward to Northeast Asia and further modulates the Okhotsk high and East Asia trough. Further analyses indicate that the weakened connection between the tropical SST_Indian anomalies and the northern Ferrell circulation likely contributes to the weakening of the NECWP-SST_Indian relationship after the 1990s. However, the eastward shift and the enlarged anomalous magnitudes of the North Atlantic Oscillation might favor the strengthening of the NECWP-SST_Atlantic relationship after the mid-1990s. It is therefore suggested that the strengthened variability of the SST_Atlantic anomalies after the 1990s might partially contribute to the intensification of the interannual variability of the NECWP.

  11. Cancer mortality and radioactive fallout in southwestern Utah

    International Nuclear Information System (INIS)

    Machado, S.G.; Land, C.E.; McKay, F.W.

    1987-01-01

    Cancer mortality was compared between a three-county region in southwestern Utah and the remainder of Utah in an investigation of reported excess cancer risks associated with residence in southwestern Utah during the period of above-ground nuclear tests at the Nevada Test Site. Because most of the fallout in southwestern Utah was deposited during 1953-1957, comparisons were limited to persons born before 1958, and deaths from leukemia and bone cancer during 1955-1980 and from other cancers during 1964-1980. There was no excess risk of cancer mortality in southwestern Utah, for single or grouped sites, with the single exception of leukemia which showed statistically significant odds ratios of 1.45 based on 62 deaths at all ages, and 2.84 based on nine deaths at ages 0-14. The finding for childhood leukemia was based on different time periods and geographic comparisons from those of two earlier studies in which no such excess was found. Mortality from all cancer sites combined was significantly lower in southwestern Utah than in the remainder of the state, even after adjustment for the higher proportion of (lower risk) Mormons in southwestern Utah. The present results, including the positive association for leukemia, are inconsistent with the high excess risks reported by Johnson (JAMA 1984;251:230-6) based on an interview survey of cancer incidence among long-term Mormon residents of southwestern Utah

  12. Isotopes in tropical agriculture

    International Nuclear Information System (INIS)

    1962-01-01

    Ways in which the use of radioisotopes and radiation can help to improve the agriculture of tropical Africa were discussed by a panel of experts. The panel included scientists from Africa, Europe, and the United States, most of whom had had actual experience dealing with agricultural problems in various parts of tropical Africa. The experts agreed that radioisotopes and radiation might now be employed to particular advantage in tropical Africa to improve crop nutrition and combat insect pests. Other applications discussed were in the fields of hydrology, plant breeding and food preservation

  13. Southwestern Institute of Physics: Annual Report 1998

    International Nuclear Information System (INIS)

    1999-10-01

    The main achievements of controlled nuclear fusion research are presented for Southwestern Institute of Physics in 1998 year. With the establishment and operation of two auxiliary heating systems (NBI, ICRH), the HL-1M Tokamak is equipped with main auxiliary heating and current driving systems such as NBI, ECRH, ICRH and LHCD etc. . In addition, a variety of advanced fueling system, i.e. , multi-shot pellet and supersonic molecular beam injection, the first wall processing technologies of boronization, siliconization and lithiumization as well as more than 20 diagnostic facilities with partial space-time resolution capability have been established on the device. The construction of a larger Tokamak with divertors, the HL-2A, and its complementary systems are being carried out

  14. Environmental Assessment for power marketing policy for Southwestern Power Administration

    International Nuclear Information System (INIS)

    1993-01-01

    Southwestern Power Administration (Southwestern) needs to renew expiring power sales contracts with new term (10 year) sales contracts. The existing contracts have been in place for several years and many will expire over the next ten years. Southwestern completed an Environmental Assessment on the existing power allocation in June, 1979 (a copy of the EA is attached), and there are no proposed additions of any major new generation resources, service to discrete major new loads, or major changes in operating parameters, beyond those included in the existing power allocation. Impacts from a no action plan, proposed alternative, and market power for less than 10 years are described

  15. Study on climate change in Southwestern China

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zongxing

    2015-03-01

    Nominated by Chinese Academy of Sciences as an outstanding Ph.D. thesis. Offers a needed exploration of the temporal and spatial pattern of climate change in southwestern China. Explores the action mechanism among the large-scale atmospheric circulation system, the complicated topography, human activities and regional climate changes. Analyzes the response of glaciers to climate change from the aspects of morphology of the glacier, glacial mass balance and the process of hydrology. This thesis confirms many changes, including sharp temperature rise, interannual variability of precipitation, extreme climate events and significant decreases of sunshine duration and wind speed in southwestern China, and systemically explores the action mechanism between large-scale atmospheric circulation systems, the complicated topography, human activities and regional climate changes. This study also analyzes the response of glaciers to climate change so that on the one hand it clearly reflects the relationship between glacier morphologic changes and climate change; on the other, it reveals the mechanism of action of climate warming as a balance between energy and matter. The achievements of this study reflect a significant contribution to the body of research on the response of climate in cold regions, glaciers and human activities to a global change against the background of the typical monsoon climate, and have provided scientific basis for predictions, countermeasures against disasters from extreme weather, utilization of water and the establishment of counterplans to slow and adapt to climate change. Zongxing Li works at the Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, China.

  16. Study on climate change in Southwestern China

    International Nuclear Information System (INIS)

    Li, Zongxing

    2015-01-01

    Nominated by Chinese Academy of Sciences as an outstanding Ph.D. thesis. Offers a needed exploration of the temporal and spatial pattern of climate change in southwestern China. Explores the action mechanism among the large-scale atmospheric circulation system, the complicated topography, human activities and regional climate changes. Analyzes the response of glaciers to climate change from the aspects of morphology of the glacier, glacial mass balance and the process of hydrology. This thesis confirms many changes, including sharp temperature rise, interannual variability of precipitation, extreme climate events and significant decreases of sunshine duration and wind speed in southwestern China, and systemically explores the action mechanism between large-scale atmospheric circulation systems, the complicated topography, human activities and regional climate changes. This study also analyzes the response of glaciers to climate change so that on the one hand it clearly reflects the relationship between glacier morphologic changes and climate change; on the other, it reveals the mechanism of action of climate warming as a balance between energy and matter. The achievements of this study reflect a significant contribution to the body of research on the response of climate in cold regions, glaciers and human activities to a global change against the background of the typical monsoon climate, and have provided scientific basis for predictions, countermeasures against disasters from extreme weather, utilization of water and the establishment of counterplans to slow and adapt to climate change. Zongxing Li works at the Cold and Arid Region Environmental and Engineering Research Institute, Chinese Academy of Sciences, China.

  17. Effect of remote sea surface temperature change on tropical cyclone potential intensity.

    Science.gov (United States)

    Vecchi, Gabriel A; Soden, Brian J

    2007-12-13

    The response of tropical cyclone activity to global warming is widely debated. It is often assumed that warmer sea surface temperatures provide a more favourable environment for the development and intensification of tropical cyclones, but cyclone genesis and intensity are also affected by the vertical thermodynamic properties of the atmosphere. Here we use climate models and observational reconstructions to explore the relationship between changes in sea surface temperature and tropical cyclone 'potential intensity'--a measure that provides an upper bound on cyclone intensity and can also reflect the likelihood of cyclone development. We find that changes in local sea surface temperature are inadequate for characterizing even the sign of changes in potential intensity, but that long-term changes in potential intensity are closely related to the regional structure of warming; regions that warm more than the tropical average are characterized by increased potential intensity, and vice versa. We use this relationship to reconstruct changes in potential intensity over the twentieth century from observational reconstructions of sea surface temperature. We find that, even though tropical Atlantic sea surface temperatures are currently at a historical high, Atlantic potential intensity probably peaked in the 1930s and 1950s, and recent values are near the historical average. Our results indicate that--per unit local sea surface temperature change--the response of tropical cyclone activity to natural climate variations, which tend to involve localized changes in sea surface temperature, may be larger than the response to the more uniform patterns of greenhouse-gas-induced warming.

  18. Pneumonia in the tropics.

    Science.gov (United States)

    Lim, Tow Keang; Siow, Wen Ting

    2018-01-01

    Pneumonia in the tropics poses a heavy disease burden. The complex interplay of climate change, human migration influences and socio-economic factors lead to changing patterns of respiratory infections in tropical climate but also increasingly in temperate countries. Tropical and poorer countries, especially South East Asia, also bear the brunt of the global tuberculosis (TB) pandemic, accounting for almost one-third of the burden. But, as human migration patterns evolve, we expect to see more TB cases in higher income as well as temperate countries, and rise in infections like scrub typhus from ecotourism activities. Fuelled by the ease of air travel, novel zoonotic infections originating from the tropics have led to global respiratory pandemics. As such, clinicians worldwide should be aware of these new conditions as well as classical tropical bacterial pneumonias such as melioidosis. Rarer entities such as co-infections of leptospirosis and chikungunya or dengue will need careful consideration as well. In this review, we highlight aetiologies of pneumonia seen more commonly in the tropics compared with temperate regions, their disease burden, variable clinical presentations as well as impact on healthcare delivery. © 2017 Asian Pacific Society of Respirology.

  19. Regional influence of decadal to multidecadal Atlantic Oscillations in Morocco during the last 1200 years

    Science.gov (United States)

    Ait Brahim, Y.; Sifeddine, A.; Cheng, H.; Khodri, M.; Cruz, F. W., Sr.; Pérez-Zanón, N.; SHA, L.; Wassenburg, J. A.; Bouchaou, L.

    2016-12-01

    Climate projections predict a substantial increase of extreme heats and drought occurrences during the coming decades in Morocco, while already under severe water stress. It is however not clear what can be attributed to natural climate variability and to anthropogenic forcing, as hydroclimate variations observed in areas such as Morocco are highly influenced by the Atlantic climate modes. Since observational data sets are too short to resolve properly natural modes of variability acting on decadal to multidecadal timescales, high resolution paleoclimate reconstructions are the only alternative to reconstruct climate variability in the remote past. However, the climate processes are still poorly understood in North Africa, which makes the investigation of hydroclimate variations during the last millennium in Morocco highly requested. Here, we present the first well-dated high resolution ( 1.7 years) stable oxygen isotope (δ18O) speleothem record from southwestern Morocco, covering the last 1200 years. Our record reveals substantial decadal to multidecadal swings between dry and humid periods, consistent with regional paleorecords, with prevailing dry conditions during the Medieval Climate Anomaly (MCA), wetter conditions during the Little Ice Age (LIA), and a trend towards dry conditions during the current warm period. These coherent regional climate signals suggest common climate controls. Statistical analyses indicate that the climate of southwestern Morocco remained under the combined influence of both the Atlantic Multidecadal Oscillation (AMO) and the North Atlantic Oscillation (NAO) over the last millennium. Interestingly, the generally warmer MCA and colder LIA at longer multidecadal timescales probably influenced the regional climate in North Africa through the influence on Sahara Low which weakened and strengthened the mean moisture inflow from the Atlantic Ocean during the MCA and LIA respectively.

  20. Shear wave splitting in the Isparta Angle, southwestern Turkey ...

    Indian Academy of Sciences (India)

    broadband station in the Isparta Angle,southwestern Turkey.We selected 21 good quality seismic events out of nearly 357 earthquakes and calculated splitting parameters (polarization direction of fast wave, and delay time between fast and ...

  1. Bone foreshafts from a clovis burial in southwestern montana.

    Science.gov (United States)

    Lahren, L; Bonnichsen, R

    1974-10-11

    Formal and functional analyses of bone artifacts from a Clovis burial in southwestern Montana suggest that they were constructed to serve as (detachable or nondetachable) foreshafts for attaching fluted projectile points to lance shafts.

  2. Seasonal mixed layer heat balance of the southwestern tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Foltz, G.R.; Vialard, J.; PraveenKumar, B.; McPhaden, M.J.

    –2004 from the Simple Ocean Data235 Assimilation (SODA; Carton et al. 2000). The covariance term is zero in the annual236 mean averaged over the SCTR region, and the magnitude of each monthly value is237 <4Wm −2 . The weakness of this term in comparison... (stronger) shear tend to reduce (enhance) the magnitude of435 w e . Since we cannot reliably estimate Δv from observations alone, we have used the436 mean seasonal cycle from SODA (2000–2004) repeated for each year.437 The constants m, n,ands are empirically...

  3. North Atlantic explosive cyclones and large scale atmospheric variability modes

    Science.gov (United States)

    Liberato, Margarida L. R.

    2015-04-01

    Extreme windstorms are one of the major natural catastrophes in the extratropics, one of the most costly natural hazards in Europe and are responsible for substantial economic damages and even fatalities. During the last decades Europe witnessed major damage from winter storms such as Lothar (December 1999), Kyrill (January 2007), Klaus (January 2009), Xynthia (February 2010), Gong (January 2013) and Stephanie (February 2014) which exhibited uncommon characteristics. In fact, most of these storms crossed the Atlantic in direction of Europe experiencing an explosive development at unusual lower latitudes along the edge of the dominant North Atlantic storm track and reaching Iberia with an uncommon intensity (Liberato et al., 2011; 2013; Liberato 2014). Results show that the explosive cyclogenesis process of most of these storms at such low latitudes is driven by: (i) the southerly displacement of a very strong polar jet stream; and (ii) the presence of an atmospheric river (AR), that is, by a (sub)tropical moisture export over the western and central (sub)tropical Atlantic which converges into the cyclogenesis region and then moves along with the storm towards Iberia. Previous studies have pointed to a link between the North Atlantic Oscillation (NAO) and intense European windstorms. On the other hand, the NAO exerts a decisive control on the average latitudinal location of the jet stream over the North Atlantic basin (Woollings et al. 2010). In this work the link between North Atlantic explosive cyclogenesis, atmospheric rivers and large scale atmospheric variability modes is reviewed and discussed. Liberato MLR (2014) The 19 January 2013 windstorm over the north Atlantic: Large-scale dynamics and impacts on Iberia. Weather and Climate Extremes, 5-6, 16-28. doi: 10.1016/j.wace.2014.06.002 Liberato MRL, Pinto JG, Trigo IF, Trigo RM. (2011) Klaus - an exceptional winter storm over Northern Iberia and Southern France. Weather 66:330-334. doi:10.1002/wea.755 Liberato

  4. Lanternfish (Myctophidae from eastern Brazil, southwest Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Adriana da Costa Braga

    2014-03-01

    Full Text Available Twenty-nine species from 11 genera of Myctophidae were taken in daytime midwater and bottom trawl hauls off eastern Brazil (11º-22ºS. Trawls were performed aboard the French R/V Thalassa to depths from 19 to 2271 m, including samples from shelf, slope and in the vicinity of oceanic banks and seamounts. Diaphus garmani was the most abundant species, accounting for 84% of all identified individuals and with four other species (D. dumerilii, D. brachycephalus, D. perspicillatus and Myctophum obtusirostre accounted for >95% of all myctophids caught. Regarding longitudinal distribution patterns, 16 species are broadly tropical, seven tropical, three subtropical, two temperate and one amphi-Atlantic. For the most abundant and frequent species, highest abundances were associated mainly with cold waters, either South Atlantic Central Water or Antarctic Intermediate Water. Non-metric multidimensional scaling based on species presence-absence in the samples and oceanographic conditions was used to identify spatial distribution of myctophid assemblages. Three assemblages were identified in the studied area: north of Abrolhos Bank, south of Abrolhos Bank, and seamounts.

  5. Impacts of hemispheric solar geoengineering on tropical cyclone frequency.

    Science.gov (United States)

    Jones, Anthony C; Haywood, James M; Dunstone, Nick; Emanuel, Kerry; Hawcroft, Matthew K; Hodges, Kevin I; Jones, Andy

    2017-11-14

    Solar geoengineering refers to a range of proposed methods for counteracting global warming by artificially reducing sunlight at Earth's surface. The most widely known solar geoengineering proposal is stratospheric aerosol injection (SAI), which has impacts analogous to those from volcanic eruptions. Observations following major volcanic eruptions indicate that aerosol enhancements confined to a single hemisphere effectively modulate North Atlantic tropical cyclone (TC) activity in the following years. Here we investigate the effects of both single-hemisphere and global SAI scenarios on North Atlantic TC activity using the HadGEM2-ES general circulation model and various TC identification methods. We show that a robust result from all of the methods is that SAI applied to the southern hemisphere would enhance TC frequency relative to a global SAI application, and vice versa for SAI in the northern hemisphere. Our results reemphasise concerns regarding regional geoengineering and should motivate policymakers to regulate large-scale unilateral geoengineering deployments.

  6. Two millennia of Mesoamerican monsoon variability driven by Pacific and Atlantic synergistic forcing

    Science.gov (United States)

    Lachniet, Matthew S.; Asmerom, Yemane; Polyak, Victor; Bernal, Juan Pablo

    2017-01-01

    The drivers of Mesoamerican monsoon variability over the last two millennia remain poorly known because of a lack of precisely-dated and climate-calibrated proxy records. Here, we present a new high resolution (∼2 yrs) and precisely-dated (± 4 yr) wet season hydroclimate reconstruction for the Mesoamerican sector of the North American Monsoon over the past 2250 years based on two aragonite stalagmites from southwestern Mexico which replicate oxygen isotope variations over the 950-1950 CE interval. The reconstruction is quantitatively calibrated to instrumental rainfall variations in the Basin of Mexico. Comparisons to proxy indices of ocean-atmosphere circulation show a synergistic forcing by the North Atlantic and El Niño/Southern Oscillations, whereby monsoon strengthening coincided with a La Niña-like mode and a negative North Atlantic Oscillation, and vice versa for droughts. Our data suggest that weak monsoon intervals are associated with a strong North Atlantic subtropical high pressure system and a weak Intertropical convergence zone in the eastern Pacific Ocean. Population expansions at three major highland Mexico civilization of Teotihuacan, Tula, and Aztec Tenochtitlan were all associated with drought to pluvial transitions, suggesting that urban population growth was favored by increasing freshwater availability in the semi-arid Mexican highlands, and that this hydroclimatic change was controlled by Pacific and Atlantic Ocean forcing.

  7. Tropical Hydroclimate Change during Heinrich Stadial 1: An Integrative Proxy-Model Synthesis

    Science.gov (United States)

    Lawman, A. E.; Sun, T.; Shanahan, T. M.; Di Nezio, P. N.; Gomez, K.; Piatrunia, N.; Sun, C.; Wu, X.; Kageyama, M.; Merkel, U.; Otto-Bliesner, B. L.; Abe-Ouchi, A.; Lohmann, G.; Singarayer, J. S.

    2017-12-01

    We explore the response of tropical climate to abrupt cooling of the North Atlantic (NA) during Heinrich Stadial 1 (HS1) combining paleoclimate proxies with model simulations. A total of 146 published paleoclimate records from tropical locations are used to categorize whether HS1 was wetter, drier, or unchanged relative to a deglacial baseline state. Only records with sufficient resolution to resolve HS1 and sufficient length to characterize the deglacial trend are considered. This synthesis reveals large-scale patterns of hydroclimate change relative to glacial conditions, confirming previously reported weaker Indian summer monsoon, a wetter southern Africa, and drying over the Caribbean. Our synthesis also reveals large-scale drying over the Maritime continent as well as wetter conditions in northern Australia and southern tropical South America. Our reinterpretation of the available proxy data reveals far more complexity and uncertainties for equatorial East Africa, a region that appears to straddle a pattern of dryer conditions to the north and wetter conditions to the south. Overall, these patterns of hydroclimate change depart from a southward shift of the Inter Tropical Convergence Zone (ITCZ), particularly outside the tropical Atlantic. We explore mechanisms driving these changes using a multi-model ensemble of "hosing" simulations performed relative to glacial conditions. The models show robust weakening of the Afro-Asian Monsoon, which we attribute to ventilation of colder mid-latitude air. Not all models simulate the remaining patterns inferred from the proxy data. The best-agreeing models indicate that cooling over the tropical NA and the Caribbean may be essential to communicate the response to the global tropics. This response can induce warming over the tropical South Atlantic via the wind-evaporation-SST feedback, driving wetter conditions in South Africa and tropical South America. Cooling over the Caribbean is communicated to the Pacific over the

  8. Large-scale factors in tropical and extratropical cyclone transition and extreme weather events.

    Science.gov (United States)

    Pezza, Alexandre Bernardes; Simmonds, Ian

    2008-12-01

    Transition mechanisms characterizing changes from hurricanes to midlatitude cyclones and vice-versa (extratropical and tropical transition) have become a topic of increasing interest, partially because of their association with recent unusual storms that have developed in different ocean basins of both hemispheres. The aim of this work is to discuss some recent cases of transition and highly unusual hurricane developments and to address some of their wider implications for climate science. Frequently those dramatic cyclones are responsible for severe weather, potentially causing significant damage to property and infrastructure. An additional manifestation discussed here is their association with cold surges, a topic that has been very little explored in the literature. In the Southern Hemisphere, the first South Atlantic hurricane, Catarina, developed in March 2004 under very unusual large-scale conditions. That exceptional cyclone is viewed as a case of tropical transition facilitated by a well-developed blocking structure. A new index for monitoring tropical transition in the subtropical South Atlantic is discussed. This "South Atlantic index" is used to show that the unusual flow during and prior to Catarina's genesis can be attributed to tropical/extratropical interaction mechanisms. The "Donald Duck" case in Australia and Vince in the North Atlantic have also been examined and shown to belong to a category of hybrid-transitioning systems that will achieve at least partial tropical transition. While clearly more research is needed on the topic of transition, as we gain further insight, it is becoming increasingly apparent that features of large-scale circulation do play a fundamental role. A complex interaction between an extratropical transition case and an extreme summer cold surge affecting southeastern Australia is discussed as an example of wider climate implications.

  9. Nonlinearity of the Extratropical Response to Tropical Forcing.

    Science.gov (United States)

    Lin, Hai; Derome, Jacques

    2004-07-01

    A primitive equations dry atmospheric model is used to investigate the atmospheric response to a tropical diabatic forcing pattern and explore how the atmospheric response changes as a function of the amplitude of the forcing. The forcing anomaly represents a linear fit of the model forcing to a tropical SST pattern of an El Niño/La Niña type. The time-averaged 500-hPa geopotential height anomaly responses of two long integrations, with forcing anomalies of equal amplitudes but opposite signs, show an asymmetric feature that is similar to observations and to previous modeling results related to El Niño and La Niña. Ensemble experiments with 61 different amplitudes of this forcing pattern are conducted. An EOF analysis of the ensemble mean of the 90-day-averaged 500-hPa height for different amplitudes of forcings shows that the leading mode of the forced variability resembles the Pacific North American (PNA) pattern, while the second mode is a wave train across the North Atlantic to Eurasia. The relationship between the amplitude of the PNA mode and the amplitude of the forcing is linear, while the amplitude of the Atlantic/Eurasian mode has a nearly parabolic relationship with the amplitude of the forcing. A set of linear experiments with forcing perturbations and eddy flux anomalies associated with the positive and negative amplitudes of forcing conditions indicates that the nonlinearity of the extratropical response primarily results from the modification of the “basic state” caused by the large-amplitude forcing and the subsequent sensitivity of the response to that modified basic flow. A La Niña type basic state yields a stronger response in the North Atlantic to the tropical Pacific forcing than does an El Niño type basic state.

  10. SPURS: Salinity Processes in the Upper-Ocean Regional Study: THE NORTH ATLANTIC EXPERIMENT

    Science.gov (United States)

    Lindstrom, Eric; Bryan, Frank; Schmitt, Ray

    2015-01-01

    In this special issue of Oceanography, we explore the results of SPURS-1, the first part of the ocean process study Salinity Processes in the Upper-ocean Regional Study (SPURS). The experiment was conducted between August 2012 and October 2013 in the subtropical North Atlantic and was the first of two experiments (SPURS come in pairs!). SPURS-2 is planned for 20162017 in the tropical eastern Pacific Ocean.

  11. The impact of edge effect on termite community (Blattodea: Isoptera) in fragments of Brazilian Atlantic Rainforest

    OpenAIRE

    Almeida,C. S.; Cristaldo,P. F.; Florencio,D. F.; Ribeiro,E. J. M.; Cruz,N. G.; Silva,E. A.; Costa,D. A.; Araújo,A. P. A.

    2016-01-01

    Abstract Habitat fragmentation is considered to be one of the biggest threats to tropical ecosystem functioning. In this region, termites perform an important ecological role as decomposers and ecosystem engineers. In the present study, we tested whether termite community is negatively affected by edge effects on three fragments of Brazilian Atlantic Rainforest. Termite abundance and vegetation structure were sampled in 10 transects (15 × 2 m), while termite richness, activity, and soil litte...

  12. Landslide monitoring in the Atlantic Highlands area, New Jersey

    Science.gov (United States)

    Reilly, Pamela A.; Ashland, Francis X.; Fiore, Alex R.

    2017-08-25

    Shallow and deep-seated landslides have occurred episodically on the steep coastal bluffs of the Atlantic Highlands area (Boroughs of Atlantic Highlands and Highlands) in New Jersey. The oldest documented deep-seated landslide occurred in April 1782 and significantly changed the morphology of the bluff. However, recent landslides have been mostly shallow in nature and have occurred during large storms with exceptionally heavy rainfall. These shallow landslides have resulted in considerable damage to residential property and local infrastructure and threatened human safety.The recent shallow landslides in the area (locations modified from New Jersey Department of Environmental Protection) consist primarily of slumps and flows of earth and debris within areas of historical landslides or on slopes modified by human activities. Such landslides are typically triggered by increases in shallow soil moisture and pore-water pressure caused by sustained and intense rainfall associated with spring nor’easters and late summer–fall tropical cyclones. However, the critical relation between rainfall, soil-moisture conditions, and landslide movement has not been fully defined. The U.S. Geological Survey is currently monitoring hillslopes within the Atlantic Highlands area to better understand the hydrologic and meteorological conditions associated with shallow landslide initiation.

  13. Aerosol interactions with African/