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Sample records for proxy temperature record

  1. Multi-periodic climate dynamics: spectral analysis of long-term instrumental and proxy temperature records

    OpenAIRE

    H.-J. Lüdecke; A. Hempelmann; Weiss, C. O.

    2012-01-01

    The longest six instrumental temperature records of monthly means reach back maximally to 1757 AD and were recorded in Europe. All six show a V-shape, with temperature drop in the 19th and rise in the 20th century. Proxy temperature time series of Antarctic ice cores show this same characteristic shape, indicating this pattern as a global phenomenon. We used the mean of the 6 instrumental records for analysis by discrete Fourier transformation (DFT), wavelets, and the detrended fluctuati...

  2. Multi-periodic climate dynamics: spectral analysis of long-term instrumental and proxy temperature records

    OpenAIRE

    Lüdecke, H.-J.; A. Hempelmann; Weiss, C. O.

    2013-01-01

    The longest six instrumental temperature records of monthly means reach back maximally to 1757 AD and were recorded in Europe. All six show a V-shape, with temperature drop in the 19th and rise in the 20th century. Proxy temperature time series of Antarctic ice cores show this same characteristic shape, indicating this pattern as a global phenomenon. We used the mean of the six instrumental records for analysis by discrete Fourier transform (DFT), wavelets, and the detren...

  3. Multi-periodic climate dynamics: spectral analysis of long-term instrumental and proxy temperature records

    Science.gov (United States)

    Lüdecke, H.-J.; Hempelmann, A.; Weiss, C. O.

    2013-02-01

    The longest six instrumental temperature records of monthly means reach back maximally to 1757 AD and were recorded in Europe. All six show a V-shape, with temperature drop in the 19th and rise in the 20th century. Proxy temperature time series of Antarctic ice cores show this same characteristic shape, indicating this pattern as a global phenomenon. We used the mean of the six instrumental records for analysis by discrete Fourier transform (DFT), wavelets, and the detrended fluctuation analysis (DFA). For comparison, a stalagmite record was also analyzed by DFT. The harmonic decomposition of the abovementioned mean shows only six significant frequencies above periods over 30 yr. The Pearson correlation between the mean, smoothed by a 15-yr running average (boxcar) and the reconstruction using the six significant frequencies, yields r = 0.961. This good agreement has a > 99.9% confidence level confirmed by Monte Carlo simulations. It shows that the climate dynamics is governed at present by periodic oscillations. We find indications that observed periodicities result from intrinsic dynamics.

  4. Multi-periodic climate dynamics: spectral analysis of long-term instrumental and proxy temperature records

    Directory of Open Access Journals (Sweden)

    H.-J. Lüdecke

    2013-02-01

    Full Text Available The longest six instrumental temperature records of monthly means reach back maximally to 1757 AD and were recorded in Europe. All six show a V-shape, with temperature drop in the 19th and rise in the 20th century. Proxy temperature time series of Antarctic ice cores show this same characteristic shape, indicating this pattern as a global phenomenon. We used the mean of the six instrumental records for analysis by discrete Fourier transform (DFT, wavelets, and the detrended fluctuation analysis (DFA. For comparison, a stalagmite record was also analyzed by DFT. The harmonic decomposition of the abovementioned mean shows only six significant frequencies above periods over 30 yr. The Pearson correlation between the mean, smoothed by a 15-yr running average (boxcar and the reconstruction using the six significant frequencies, yields r = 0.961. This good agreement has a > 99.9% confidence level confirmed by Monte Carlo simulations. It shows that the climate dynamics is governed at present by periodic oscillations. We find indications that observed periodicities result from intrinsic dynamics.

  5. Seemingly divergent sea surface temperature proxy records in the central Mediterranean during the last deglaciation

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    M.-A. Sicre

    2013-06-01

    Full Text Available Sea surface temperatures (SSTs were reconstructed over the last 25 000 yr using alkenone paleothermometry and planktonic foraminifera assemblages from two cores of the central Mediterranean Sea: the MD04-2797 core (Siculo–Tunisian channel and the MD90-917 core (South Adriatic Sea. Comparison of the centennial scale structure of the two temperature signals during the last deglaciation period reveals significant differences in timing and amplitude. We suggest that seasonal changes likely account for seemingly proxy record divergences during abrupt transitions from glacial to interglacial climates and for the apparent short duration of the Younger Dryas (YD depicted by the alkenone time series, a feature that has already been stressed in earlier studies on the Mediterranean deglaciation.

  6. Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea

    Science.gov (United States)

    Kuffner, Ilsa B.; Roberts, Kelsey E.; Flannery, Jennifer A.; Morrison, Jennifer M.; Richey, Julie N.

    2017-01-01

    Massive corals provide a useful archive of environmental variability, but careful testing of geochemical proxies in corals is necessary to validate the relationship between each proxy and environmental parameter throughout the full range of conditions experienced by the recording organisms. Here we use samples from a coral-growth study to test the hypothesis that Sr/Ca in the coral Siderastrea siderea accurately records sea-surface temperature (SST) in the subtropics (Florida, USA) along 350 km of reef tract. We test calcification rate, measured via buoyant weight, and linear extension (LE) rate, estimated with Alizarin Red-S staining, as predictors of variance in the Sr/Ca records of 39 individual S. siderea corals grown at four outer-reef locations next to in-situ temperature loggers during two, year-long periods. We found that corals with calcification rates quality-control indicator during sample and drill-path selection when using long cores for SST paleoreconstruction. For our corals that passed this quality control step, the Sr/Ca-SST proxy performed well in estimating mean annual temperature across three sites spanning 350 km of the Florida reef tract. However, there was some evidence that extreme temperature stress in 2010 (cold snap) and 2011 (SST above coral-bleaching threshold) may have caused the corals not to record the temperature extremes. Known stress events could be avoided during modern calibrations of paleoproxies.Plain Language SummaryCoral skeletons are used to decipher past environmental conditions in the ocean because they live for centuries and produce annual growth bands much like tree rings. Along with measuring coral growth rates in the past, coral skeletons can be chemically sampled to get even more detailed information, like past seawater temperatures. In this study we tested the validity of the strontium-to-calcium (Sr/Ca) temperature proxy in the Massive Starlet Coral (Siderastrea siderea) by sampling 39 corals that were grown in the

  7. Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea

    Science.gov (United States)

    Kuffner, Ilsa B.; Roberts, Kelsey E.; Flannery, Jennifer A.; Morrison, Jennifer M.; Richey, Julie

    2017-01-01

    Massive corals provide a useful archive of environmental variability, but careful testing of geochemical proxies in corals is necessary to validate the relationship between each proxy and environmental parameter throughout the full range of conditions experienced by the recording organisms. Here we use samples from a coral-growth study to test the hypothesis that Sr/Ca in the coral Siderastrea siderea accurately records sea-surface temperature (SST) in the subtropics (Florida, USA) along 350 km of reef tract. We test calcification rate, measured via buoyant weight, and linear extension (LE) rate, estimated with Alizarin Red-S staining, as predictors of variance in the Sr/Ca records of 39 individual S. siderea corals grown at four outer-reef locations next to in-situ temperature loggers during two, year-long periods. We found that corals with calcification rates mean annual temperature across three sites spanning 350 km of the Florida reef tract. However, there was some evidence that extreme temperature stress in 2010 (cold snap) and 2011 (SST above coral-bleaching threshold) may have caused the corals not to record the temperature extremes. Known stress events could be avoided during modern calibrations of paleoproxies.

  8. Inferring climate variability from skewed proxy records

    Science.gov (United States)

    Emile-Geay, J.; Tingley, M.

    2013-12-01

    compared to other proxy records. (2) a multiproxy reconstruction of temperature over the Common Era (Mann et al., 2009), where we find that about one third of the records display significant departures from normality. Accordingly, accounting for skewness in proxy predictors has a notable influence on both reconstructed global mean and spatial patterns of temperature change. Inferring climate variability from skewed proxy records thus requires cares, but can be done with relatively simple tools. References - Mann, M. E., Z. Zhang, S. Rutherford, R. S. Bradley, M. K. Hughes, D. Shindell, C. Ammann, G. Faluvegi, and F. Ni (2009), Global signatures and dynamical origins of the little ice age and medieval climate anomaly, Science, 326(5957), 1256-1260, doi:10.1126/science.1177303. - Moy, C., G. Seltzer, D. Rodbell, and D. Anderson (2002), Variability of El Niño/Southern Oscillation activ- ity at millennial timescales during the Holocene epoch, Nature, 420(6912), 162-165.

  9. Impact of precipitation intermittency on NAO-temperature signals in proxy records

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    M. Casado

    2013-03-01

    Full Text Available In mid and high latitudes, the stable isotope ratio in precipitation is driven by changes in temperature, which control atmospheric distillation. This relationship forms the basis for many continental paleoclimatic reconstructions using direct (e.g. ice cores or indirect (e.g. tree ring cellulose, speleothem calcite archives of past precipitation. However, the archiving process is inherently biased by intermittency of precipitation. Here, we use two sets of atmospheric reanalyses (NCEP (National Centers for Environmental Prediction and ERA-interim to quantify this precipitation intermittency bias, by comparing seasonal (winter and summer temperatures estimated with and without precipitation weighting. We show that this bias reaches up to 10 °C and has large interannual variability. We then assess the impact of precipitation intermittency on the strength and stability of temporal correlations between seasonal temperatures and the North Atlantic Oscillation (NAO. Precipitation weighting reduces the correlation between winter NAO and temperature in some areas (e.g. Québec, South-East USA, East Greenland, East Siberia, Mediterranean sector but does not alter the main patterns of correlation. The correlations between NAO, δ18O in precipitation, temperature and precipitation weighted temperature are investigated using outputs of an atmospheric general circulation model enabled with stable isotopes and nudged using reanalyses (LMDZiso (Laboratoire de Météorologie Dynamique Zoom. In winter, LMDZiso shows similar correlation values between the NAO and both the precipitation weighted temperature and δ18O in precipitation, thus suggesting limited impacts of moisture origin. Correlations of comparable magnitude are obtained for the available observational evidence (GNIP (Global Network of Isotopes in Precipitation and Greenland ice core data. Our findings support the use of archives of past δ18O for NAO reconstructions.

  10. Evidence of multidecadal climate variability and the Atlantic Multidecadal Oscillation from a Gulf of Mexico sea-surface temperature-proxy record

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    Poore, R.Z.; DeLong, K.L.; Richey, J.N.; Quinn, T.M.

    2009-01-01

    A comparison of a Mg/Ca-based sea-surface temperature (SST)-anomaly record from the northern Gulf of Mexico, a calculated index of variability in observed North Atlantic SST known as the Atlantic Multidecadal Oscillation (AMO), and a tree-ring reconstruction of the AMO contain similar patterns of variation over the last 110 years. Thus, the multidecadal variability observed in the instrumental record is present in the tree-ring and Mg/Ca proxy data. Frequency analysis of the Gulf of Mexico SST record and the tree-ring AMO reconstruction from 1550 to 1990 found similar multidecadal-scale periodicities (???30-60 years). This multidecadal periodicity is about half the observed (60-80 years) variability identified in the AMO for the 20th century. The historical records of hurricane landfalls reveal increased landfalls in the Gulf Coast region during time intervals when the AMO index is positive (warmer SST), and decreased landfalls when the AMO index is negative (cooler SST). Thus, we conclude that alternating intervals of high and low hurricane landfall occurrences may continue on multidecadal timescales along the northern Gulf Coast. However, given the short length of the instrumental record, the actual frequency and stability of the AMO are uncertain, and additional AMO proxy records are needed to establish the character of multidecadal-scale SST variability in the North Atlantic. ?? 2009 US Government.

  11. A High-Resolution Multi-Proxy Lake Sediment Record from Torfdalsvatn Suggests an Enhanced Temperature Gradient Between North and South Iceland During the Early Holocene

    Science.gov (United States)

    Florian, Christopher; Geirsdóttir, Áslaug; Miller, Gifford; Axford, Yarrow

    2015-04-01

    Torfdalsvatn (66° 3'41.73"N, 20°23'14.26"W) is a relatively small (0.4 km2) and shallow (z=5.8 m) lake on the Skagi Peninsula of northern Iceland approximately 0.5 km from the modern coastline. This location is ideal for comparison with the many marine core records from the North Iceland Shelf that record variability in the northern extent of the warm Irminger Current, one of the primary controls on regional climate. To develop a record of north Iceland Holocene terrestrial climate, we analyzed a 8.4 m sediment core at 15-30 year resolution from approximately 12 ka to present using multiple proxies including sedimentary pigments, organic carbon flux, carbon to nitrogen ratio and stable isotopes, as well as biogenic silica measured by Fourier Transform Infrared Spectroscopy (FTIR-S). Results show gradual warming during the early Holocene, with stable soil development and peak aquatic productivity not occurring until after 8 ka. Increased aquatic productivity and a stable terrestrial environment between 6 and 2 ka indicate peak Holocene warmth in this interval. Aquatic productivity abruptly decreases at 1.8 ka associated with an increase in minerogenic material from landscape destabilization in the catchment with the onset of late Holocene cooling. At 1ka, the proportion of terrestrially-derived organic matter deposited in the lake sediment increases, indicating significant destabilization of soil horizons due to continued cooling and potential human settlement. This record is in good agreement with composite north Iceland chironomid-inferred July air temperatures from Axford et al. (2007), which show peak summer temperatures occurring between approximately 5 and 2 ka. The time of peak warmth at Torfdalsvatn is associated with peak biogenic carbonate concentration in the marine core MD99-2269, indicating an influx of warm Irminger waters. This is in contrast with Holocene climate records obtained from lakes in south and west Iceland, implying that there was an

  12. Proxy comparisons for Paleogene sea water temperature reconstructions

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    de Bar, Marijke; de Nooijer, Lennart; Schouten, Stefan; Ziegler, Martin; Sluijs, Appy; Reichart, Gert-Jan

    2017-04-01

    Several studies have reconstructed Paleogene seawater temperatures, using single- or multi-proxy approaches (e.g. Hollis et al., 2012 and references therein), particularly comparing TEX86 with foraminiferal δ18O and Mg/Ca. Whereas trends often agree relatively well, absolute temperatures can differ significantly between proxies, possibly because they are often applied to (extreme) climate events/transitions (e.g. Sluijs et al., 2011), where certain assumptions underlying the temperature proxies may not hold true. A more general long-term multi-proxy temperature reconstruction, is therefore necessary to validate the different proxies and underlying presumed boundary conditions. Here we apply a multi-proxy approach using foraminiferal calcite and organic proxies to generate a low-resolution, long term (80 Myr) paleotemperature record for the Bass River core (New Jersey, North Atlantic). Oxygen (δ18O), clumped isotopes (Δ47) and Mg/Ca of benthic foraminifera, as well as the organic proxies MBT'-CBT, TEX86H, U37K' index and the LDI were determined on the same sediments. The youngest samples of Miocene age are characterized by a high BIT index (>0.8) and fractional abundance of the C32 1,15-diol (>0.6; de Bar et al., 2016) and the absence of foraminifera, all suggesting high continental input and shallow depths. The older sediment layers (˜30 to 90 Ma) display BIT values and C32 1,15-diol fractional abundances global transition from the Cretaceous to Eocene greenhouse world into the icehouse climate. The TEX86H sea surface temperature (SST) record shows a gradual cooling over time of ˜35 to 20 ˚ C, whereas the δ18O-derived bottom water temperatures (BWTs) decrease from ˜20 to 10 ˚ C, and the Mg/Ca and Δ47-derived BWTs decrease from ˜25 to 15 ˚ C. The absolute temperature difference between the δ18O and Δ47, might be explained by local variations in seawater δ18O composition. Similarly, the difference in Mg/Ca- and δ18O-derived BWTs is likely caused by

  13. How different proxies record precipitation variability over southeastern South America

    Energy Technology Data Exchange (ETDEWEB)

    Chiessi, Cristiano M; Mulitza, Stefan; Paetzold, Juergen; Wefer, Gerold, E-mail: chiessi@uni-bremen.d [MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse, 28359 Bremen (Germany)

    2010-03-15

    Detrending natural and anthropogenic components of climate variability is arguably an issue of utmost importance to society. To accomplish this issue, one must rely on a comprehensive understanding of the natural variability of the climate system on a regional level. Here we explore how different proxies (e.g., stalagmite oxygen isotopic composition, pollen percentages, bulk sediment elemental ratios) record Holocene precipitation variability over southeastern South America. We found a general good agreement between the different records both on orbital and centennial time-scales. Dry mid Holocene, and wet late Holocene, Younger Dryas and a period between {approx}9.4 and 8.12 cal kyr BP seem to be pervasive features. Moreover, we show that proxy-specific sensitivity can greatly improve past precipitation reconstructions.

  14. Modelling an alkenone-like proxy record in the NW African upwelling

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    X. Giraud

    2006-01-01

    Full Text Available A regional biogeochemical model is applied to the NW African coastal upwelling between 19° N and 27° N to investigate how a water temperature proxy, alkenones, are produced at the sea surface and recorded in the slope sediments. The biogeochemical model has two phytoplankton groups: an alkenone producer group, considered to be coccolithophores, and a group comprising other phytoplankton. The Regional Ocean Modelling System (ROMS is used to simulate the ocean circulation and takes advantage of the Adaptive Grid Refinement in Fortran (AGRIF package to set up an embedded griding system. In the simulations the alkenone temperature records in the sediments are between 1.1 and 2.3°C colder than the annual mean SSTs. Despite the seasonality of the coccolithophore production, this temperature difference is not mainly due to a seasonal bias, nor to the lateral advection of phytoplankton and phytodetritus seaward from the cold near-shore waters, but to the production depth of the coccolithophores. If coretop alkenone temperatures are effectively recording the annual mean SSTs, the amount of alkenone produced must vary among the coccolithophores in the water column and depend on physiological factors (e.g. growth rate, nutrient stress.

  15. Magnetic record associated with tree ring density: Possible climate proxy

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    Pruner Petr

    2007-03-01

    Full Text Available Abstract A magnetic signature of tree rings was tested as a potential paleo-climatic indicator. We examined wood from sequoia tree, located in Mountain Home State Forest, California, whose tree ring record spans over the period 600 – 1700 A.D. We measured low and high-field magnetic susceptibility, the natural remanent magnetization (NRM, saturation isothermal remanent magnetization (SIRM, and stability against thermal and alternating field (AF demagnetization. Magnetic investigation of the 200 mm long sequoia material suggests that magnetic efficiency of natural remanence may be a sensitive paleoclimate indicator because it is substantially higher (in average >1% during the Medieval Warm Epoch (700–1300 A.D. than during the Little Ice Age (1300–1850 A.D. where it is

  16. Proxy records of Holocene storm events in coastal barrier systems: Storm-wave induced markers

    Science.gov (United States)

    Goslin, Jérôme; Clemmensen, Lars B.

    2017-10-01

    Extreme storm events in the coastal zone are one of the main forcing agents of short-term coastal system behavior. As such, storms represent a major threat to human activities concentrated along the coasts worldwide. In order to better understand the frequency of extreme events like storms, climate science must rely on longer-time records than the century-scale records of instrumental weather data. Proxy records of storm-wave or storm-wind induced activity in coastal barrier systems deposits have been widely used worldwide in recent years to document past storm events during the last millennia. This review provides a detailed state-of-the-art compilation of the proxies available from coastal barrier systems to reconstruct Holocene storm chronologies (paleotempestology). The present paper aims (I) to describe the erosional and depositional processes caused by storm-wave action in barrier and back-barrier systems (i.e. beach ridges, storm scarps and washover deposits), (ii) to understand how storm records can be extracted from barrier and back-barrier sedimentary bodies using stratigraphical, sedimentological, micro-paleontological and geochemical proxies and (iii) to show how to obtain chronological control on past storm events recorded in the sedimentary successions. The challenges that paleotempestology studies still face in the reconstruction of representative and reliable storm-chronologies using these various proxies are discussed, and future research prospects are outlined.

  17. Molybdenum isotope records as a potential new proxy for paleoceanography

    Science.gov (United States)

    Siebert, Christopher; Nägler, Thomas F.; von Blanckenburg, Friedhelm; Kramers, Jan D.

    2003-06-01

    New high-precision isotope ratios of dissolved Mo in seawater from different ocean basins and depths show a homogeneous isotope composition ('mean ocean water 98Mo/95Mo' (MOMO)), as expected from its long ocean residence time (800 kyr). This composition appears to have been constant for the past 60 Myr at a 1-3 Myr time resolution as indicated from thick sections of Fe-Mn crusts from the Atlantic and Pacific. These records yield a constant offset from MOMO (average of -3.1 and -2.9‰). They are similar to our new data on recent oxic Mo sinks: pelagic sediments and six Fe-Mn crust surface layers range from -2.7 to -2.9‰ and -2.7 to -3.1‰, respectively. Recent suboxic Mo sinks from open ocean basins display heavier and more variable isotope ratios (-0.7 to -1.6‰ relative to MOMO). Crustal Mo sources were characterized by measuring two granites (and a mild acid leach of one granite), seven volcanic rocks and two clastic sediments. All show a narrow range of compositions (-2.0 to -2.3‰). These data indicate that isotope fractionation by chemical weathering and magmatic processes is insignificant on a global scale. They therefore represent good estimates of the composition of dissolved Mo input to the oceans and that of the average continental crust. Thus, the Mo input into the oceans appears to be distributed into lighter oxic sinks and heavier reducing sinks. This is consistent with steady-state conditions in the modern ocean. The constant isotope offset between oxic sediments and seawater suggests that the relative amounts of oxic and reducing Mo removal fluxes have not varied by more than 10% over the last 60 Myr. An equilibrium fractionation process is proposed assuming that Mo isotope fractionation occurs between (dominant) MoO42- and (minor) Mo(OH)6 species in solution, of which the latter is preferentially scavenged.

  18. Proxy-based Northern Hemisphere temperature reconstruction for the mid-to-late Holocene

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    Pei, Qing; Zhang, David D.; Li, Jinbao; Lee, Harry F.

    2017-11-01

    The observed late twentieth century warming must be assessed in relation to natural long-term variations of the climatic system. Here, we present a Northern Hemisphere (NH) temperature reconstruction for the mid-to-late Holocene of the past 6000 years, based on a synthesis of existing paleo-temperature proxies that are capable of revealing centennial-scale variability. This includes 56 published temperature records across the NH land areas, with a sampling resolution ranging from 1 to 100 years and a time span of at least 1000 years. The composite plus scale (CPS) method is adopted with spatial weighting to develop the NH temperature reconstruction. Our reconstruction reveals abrupt cold epochs that match well the Bond events during the past 6000 years. The study further reveals two prominent cycles in NH temperature: 1700-2000-year cycle during the mid-to-late Holocene and 1200-1500-year cycle during the past 3500 years. Our reconstruction indicates that the late twentieth century NH temperature and its rate of warming are both unprecedentedly high over the past 5000 years. By comparing our reconstruction with the projected temperature increase scenarios, we find that temperature by the end of the twenty-first century would likely exceed any peaks during the mid-to-late Holocene.

  19. Constraining the Paleogene of South America: Magnetostratigraphy and paleoclimate proxy records from Cerro Bayo (Provincia de Salta, Argentina)

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    Hyland, E.; Cotton, J. M.; Sheldon, N. D.

    2012-12-01

    Records of rapid climatic and ecological shifts in the past are crucial for understanding global systems and for predicting future impacts of climate change. Transient and broad scale hyperthermal events during the Paleogene, such as the Paleocene-Eocene Thermal Maximum (PETM) and Early Eocene Climatic Optimum (EECO), have been studied extensively through both marine records and a significant terrestrial record from North America. Despite this, little evidence exists from the climatic and ecological histories of other major landmasses, which limits the effectiveness of global climate response predictions. Here we present an integrated paleoenvironmental reconstruction of the early Paleogene from a site in central South America (Cerro Bayo, Argentina), including a new magnetostratigraphic age model, pedological and sedimentological interpretation, whole rock geochemical climate proxies, isotopic environmental proxies, and microfloral assemblages. Cerro Bayo is a 235-meter terrestrial section that exposes the Tunal, Mealla, and Maiz Gordo Formations, and based on magnetostratigraphic interpolation spans roughly 58—50 Mya, including both the PETM and EECO events. These formations are composed primarily of reddish sandstone and siltstone, much of which exhibits features characteristic of a moderate degree of pedogenesis (i.e., Inceptisols and Alfisols). High-resolution climate proxies derived from paleosol geochemical compositions highlight rapid increases in mean annual temperature (>5°C) and precipitation (>300 mm yr-1) during the PETM, as well as more gradual increasing temperature and precipitation trends leading up to the EECO. Carbon isotope stratigraphy through the section also indicates a sizable negative excursion (~4‰) during the PETM, and generally positive isotopic trends during the early Eocene. Phytolith biostratigraphy also details changes in local vegetation composition during climatic events that corresponds to similar patterns seen in terrestrial

  20. Evaluating the skeletal chemistry of Mytilus californianus as a temperature proxy: Effects of microenvironment and ontogeny

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    Ford, Heather L.; Schellenberg, Stephen A.; Becker, Bonnie J.; Deutschman, Douglas L.; Dyck, Kelsey A.; Koch, Paul L.

    2010-01-01

    Molluscan shell chemistry may provide an important archive of mean annual temperature (MAT) and mean annual range in temperature (MART), but such direct temperature interpretations may be confounded by biologic, metabolic, or kinetic factors. To explore this potential archive, we outplanted variously sized specimens of the common mussel Mytilus californianus at relatively low and high intertidal positions in San Diego, California, for 382 days with in situ recording of ambient temperature and periodic sampling of water chemistry. The prismatic calcite layer of eight variously sized specimens from each intertidal position were then serially microsampled and geochemically analyzed. Average intraspecimen δ18O values significantly covaried only with temperature, whereas Mg/Ca values showed a strong and significant positive correlation with growth rate. To assess intra-annual variations in shell chemistry as proxy for MART, each specimen's δ18O record was ordinated in the time domain and compared to the predicted isotopic equilibrium δ18O values from environmental data. Observed specimen values were significantly correlated with predicted equilibrium values, but show 18O enrichments of 0.2 to 0.5‰. In contrast, Mg/Ca values were poorly correlated with temperature due to significant positive relationships with growth rate and intertidal position. Within the extrapallial fluid, pH, carbonate solution chemistry, Rayleigh fractionation and/or an undetermined source of disequilibrium may cause δ18O values to deviate from predicted equilibrium precipitation for ambient seawater. Despite this consistent 18O enrichment, intraskeletal variations in δ18O values readily characterize the instrumental MAT and 5-95% MART values, making M. californianus a valuable source of information for paleoceanographic reconstructions.

  1. Temperature variations in the southern Great Lakes during the last deglaciation: Comparison between pollen and GDGT proxies

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    Watson, Benjamin I.; Williams, John W.; Russell, James M.; Jackson, Stephen T.; Shane, Linda; Lowell, Thomas V.

    2018-02-01

    Our understanding of deglacial climate history in the southern Great Lakes region of the United States is primarily based upon fossil pollen data, with few independent and multi-proxy climate reconstructions. Here we introduce a new, well-dated fossil pollen record from Stotzel-Leis, OH, and a new deglacial temperature record based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) at Silver Lake, OH. We compare these new data to previously published records and to a regional stack of pollen-based temperature reconstructions from Stotzel-Leis, Silver Lake, and three other well-dated sites. The new and previously published pollen records at Stotzel-Leis are similar, but our new age model brings vegetation events into closer alignment with known climatic events such as the Younger Dryas (YD). brGDGT-inferred temperatures correlate strongly with pollen-based regional temperature reconstructions, with the strongest correlation obtained for a global soil-based brGDGT calibration (r2 = 0.88), lending confidence to the deglacial reconstructions and the use of brGDGT and regional pollen stacks as paleotemperature proxies in eastern North America. However, individual pollen records show large differences in timing, rates, and amplitudes of inferred temperature change, indicating caution with paleoclimatic inferences based on single-site pollen records. From 16.0 to 10.0ka, both proxies indicate that regional temperatures rose by ∼10 °C, roughly double the ∼5 °C estimates for the Northern Hemisphere reported in prior syntheses. Change-point analysis of the pollen stack shows accelerated warming at 14.0 ± 1.2ka, cooling at 12.6 ± 0.4ka, and warming from 11.6 ± 0.5ka into the Holocene. The timing of Bølling-Allerød (B-A) warming and YD onset in our records lag by ∼300-500 years those reported in syntheses of temperature records from the northern mid-latitudes. This discrepancy is too large to be attributed to uncertainties in radiocarbon dating, and

  2. Origin and applicability of tetraether membrane lipids as temperature proxies in French peri-urban lakes

    Science.gov (United States)

    Mainié, François; Huguet, Arnaud; Breban, Alice; Lacroix, Gérard; Anquetil, Christelle; Derenne, Sylvie

    2015-04-01

    producing GDGTs. Indeed, bacterial and archaeal GDGTs were observed to be significantly less abundant in sediments from oligotrophic lakes than in those from hypertrophic lakes. Nevertheless, the applicability of bacterial GDGTs as temperature proxies was not affected by the eutrophic status of the lakes, since temperature estimates derived from these compounds were consistent with both mean annual air temperature (11 °C) and mean summer air temperature (19 °C) recorded in the Ile-de-France region.

  3. Clay minerals as palaeomonsoon proxies: Evaluation and relevance to the late Quaternary records from SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.

    Palaeoclimatic studies are largely dependent on the quality of records and a prudent use of environmental proxy indicators. In this study, the factors affecting the detrital clay minerals in marine environment and their utility and reliability...

  4. Are Sea Surface Temperature satellite measurements reliable proxies of lagoon temperature in the South Pacific?

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    Van Wynsberge, Simon; Menkes, Christophe; Le Gendre, Romain; Passfield, Teuru; Andréfouët, Serge

    2017-12-01

    In remote coral reef environments, lagoon and reef in situ measurements of temperature are scarce. Sea Surface Temperature (SST) measured by satellite has been frequently used as a proxy of the lagoon temperature experienced by coral reef organisms (TL) especially during coral bleaching events. However, the link between SST and TL is poorly characterized. First, we compared the correlation between various SST series and TL from 2012 to 2016 in three atolls and one island in the Central South Pacific Ocean. Simple linear correlation between SST and TL ranged between 0.44 and 0.97 depending on lagoons, localities of sensors, and type of SST data. High-resolution-satellite-measurements of SST inside the lagoons did not outperform oceanic SST series, suggesting that SST products are not adapted for small lagoons. Second, we modelled the difference between oceanic SST and TL as a function of the drivers of lagoon water renewal and mixing, namely waves, tide, wind, and season. The multivariate models reduced significantly the bias between oceanic SST and TL. In atoll lagoons, and probably in other hydrodynamically semi-open systems, a correction taking into account these factors is necessary when SST are used to characterize organisms' thermal stress thresholds.

  5. The reconstruction of past climate variability in the NW Indian Ocean based on a coral proxy record from the Maldives

    OpenAIRE

    Storz, David

    2010-01-01

    Until now, the NW Indian Ocean was sparsely covered with coral proxy records, and records from the Maldives Archipelago do not exist. The first such coral proxy record from the central Maldives is presented in this study. It originates from a massive Porites lutea (Quoy and Gaimard, 1833) colony that was sampled March 2007 in the lagoon of Rasdhoo Atoll (4°N/ 73°W), which is located in the central Maldives. The record spans a period of 90 yrs and reaches back to 1917 AD with monthly to bimont...

  6. Coral proxy record of decadal-scale reduction in base flow from Moloka'i, Hawaii

    Science.gov (United States)

    Prouty, Nancy G.; Jupiter, Stacy D.; Field, Michael E.; McCulloch, Malcolm T.

    2009-01-01

    Groundwater is a major resource in Hawaii and is the principal source of water for municipal, agricultural, and industrial use. With a growing population, a long-term downward trend in rainfall, and the need for proper groundwater management, a better understanding of the hydroclimatological system is essential. Proxy records from corals can supplement long-term observational networks, offering an accessible source of hydrologic and climate information. To develop a qualitative proxy for historic groundwater discharge to coastal waters, a suite of rare earth elements and yttrium (REYs) were analyzed from coral cores collected along the south shore of Moloka'i, Hawaii. The coral REY to calcium (Ca) ratios were evaluated against hydrological parameters, yielding the strongest relationship to base flow. Dissolution of REYs from labradorite and olivine in the basaltic rock aquifers is likely the primary source of coastal ocean REYs. There was a statistically significant downward trend (−40%) in subannually resolved REY/Ca ratios over the last century. This is consistent with long-term records of stream discharge from Moloka'i, which imply a downward trend in base flow since 1913. A decrease in base flow is observed statewide, consistent with the long-term downward trend in annual rainfall over much of the state. With greater demands on freshwater resources, it is appropriate for withdrawal scenarios to consider long-term trends and short-term climate variability. It is possible that coral paleohydrological records can be used to conduct model-data comparisons in groundwater flow models used to simulate changes in groundwater level and coastal discharge.

  7. A bi-proxy reconstruction of Fontainebleau (France growing season temperature from A.D. 1596 to 2000

    Directory of Open Access Journals (Sweden)

    N. Etien

    2008-05-01

    Full Text Available In this paper, we develop a new methodology to estimate past changes of growing season temperature at Fontainebleau (northern France. Northern France temperature fluctuations have been documented by homogenised instrumental temperature records (at most 140 year long and by grape harvest dates (GHD series, incorporated in some of the European-scale temperature reconstructions. We have produced here three new proxy records: δ18O and δ13C of latewood cellulose of living trees and timbers from Fontainebleau Forest and Castle, together with ring widths of the same samples. δ13C data appear to be influenced by tree and age effects; ring widths are not controlled by a single climate parameter. By contrast, δ18O and Burgundy GHD series exhibit strong links with Fontainebleau growing season maximum temperature. Each of these records can also be influenced by other factors such as vine growing practices, local insolation, or moisture availability. In order to reduce the influence of these potential biases, we have used a linear combination of the two records to reconstruct inter-annual fluctuations of Fontainebleau growing season temperature from 1596 to 2000. Over the instrumental period, the reconstruction is well correlated with the temperature data (R2=0.60.

    This reconstruction is associated with an uncertainty of ~1.1°C (1.5 standard deviation, and is expected to provide a reference series for the variability of growing season maximum temperature in Western Europe. Spectral analyses conducted on the reconstruction clearly evidence (i the interest of combining the two proxy records in order to improve the power spectrum of the reconstructed versus observed temperature, (ii changes in the spectral properties over the time, with varying weights of periodicities ranging between ~6 and ~25 years. Available reconstructions of regional growing season temperature fluctuations get

  8. Spatial and temporal variability of Crenarchaeota in Lake Superior and implications for the application of the TEX86 temperature proxy

    Science.gov (United States)

    Woltering, M. L.; Werne, J. P.; Hicks, R. E.; Kish, J. L.; Schouten, S.; Sinninghe Damste, J. S.

    2010-12-01

    Superior, as unless the niche of export production of crenarchaeotal membrane lipids moved towards the epilimnion, temperature changes are expected to be relatively small compared to the uncertainties surrounding the TEX86 method. Our study provides insight into where and when are the lipids that make up the TEX86 proxy produced in the water column that are subsequently incorporated into the sediment record, thus placing constraints on what kind of temperature is actually represented by the TEX86 proxy in sediment records of Lake Superior or similar lacustrine systems.

  9. Late Holocene climate change recorded in proxy records from a Bransfield Basin sediment core, Antarctic Peninsula

    Directory of Open Access Journals (Sweden)

    Alex Barnard

    2014-06-01

    Full Text Available The glacimarine environment of the Antarctic Peninsula region is one of the fastest warming places on Earth today, but details of changes in the recent past remain unknown. Large distances and widespread variability separate late Holocene palaeoclimate reconstructions in this region. This study focuses on a marine sediment core collected from ca. 2000 m below sea level in the Central Bransfield Strait that serves as a key for understanding changes in this region. The core yielded a high sedimentation rate and therefore provides an exceptional high-resolution sedimentary record composed of hemipelagic sediment, with some turbidites. An age model has been created using radiocarbon dates that span the Late Holocene: 3560 cal yr BP to present. This chronostratigraphic framework was used to establish five units, which are grouped into two super-units: a lower super-unit (3560–1600 cal yr BP and an upper super-unit (1600 cal yr BP–present, based on facies descriptions, laser particle size analysis, x-ray analysis, multi-sensor core logger data, weight percentages and isotopic values of total organic carbon and nitrogen. We interpret the signal contained within the upper super-unit as an increase in surface water irradiance and/or shortening of the sea-ice season and the five units are broadly synchronous with climatic intervals across the Antarctic Peninsula region. While the general trends of regional climatic periods are represented in the Bransfield Basin core we have examined, each additional record that is obtained adds variability to the known history of the Antarctic Peninsula, rather than clarifying specific trends.

  10. Reinterpreting climate proxy records from late Quaternary Chinese loess: A detailed OSL investigation

    Science.gov (United States)

    Stevens, Thomas; Thomas, David S. G.; Armitage, Simon J.; Lunn, Hannah R.; Lu, Huayu

    2007-01-01

    Numerous authors have utilised physical properties of Chinese loess and red clay deposits to develop apparently detailed and continuous past climate records from the Miocene into the Holocene. Many of these studies have further suggested that the principal climatic agent responsible for the aeolian emplacement and diagenesis of Chinese loess, the East Asian Monsoon, has fluctuated rapidly on millennial to sub-millennial timescales, in concert with dramatic changes in the North Atlantic (Dansgaard-Oeschger cycles and Heinrich events) and the Western Pacific (El Niño Southern Oscillation). Much of this evidence is based on reconstructions and age models that are tied to assumptions concerning the nature of loess sedimentation and diagenesis, for example, the belief that loess sedimentation can be viewed as essentially continuous. Some authors have however, cast doubt on these assumptions and suggest that the application of radiometric techniques may be required to determine their validity. Recent studies utilising Optically Stimulated Luminescence (OSL) methods have reinforced these doubts and here, OSL dates obtained at 10 cm intervals from three sites along a transect across the Chinese Loess Plateau have been used, in combination with climate proxy evidence, to test the existing assumptions that underpin many palaeoclimatic reconstructions from loess. In this way, the first time-continuous and independently dated late Quaternary climate reconstruction is developed from loess. The data indicate that sedimentation is episodic and that once emplaced, loess is prone to pedogenic disturbance, diagenetic modification and in some cases erosion. The relationships between proxies and sedimentation rates are also assessed and climatic interpretations based on different age models compared. The implications of these findings for reconstructions of climate from loess are explored and comparisons are made between the developed palaeoclimate records and evidence from ice and

  11. Distribution of lacustrine Crenarchaeota in Lake Superior: implications for the application of the TEX86 temperature proxy

    Science.gov (United States)

    Woltering, M. L.; Werne, J. P.; Hicks, R.; Kish, J.; Oster, R.; Schouten, S.; Sinninghe Damsté, J. S.

    2009-12-01

    The TEX86 is a proxy that can be applied on continental lake sediments to reconstruct past water temperatures. It is based on the lipids derived from aquatic Crenarchaeota, and although first applied in marine systems has already been successfully used in sediments from some of the continental lake drilling projects in Lake Malawi and Tanganyika. Recent studies have shown that the application of this proxy in lacustrine systems appears to be limited to mainly large to intermediate size lakes that are only marginally terrestrially influenced. Here TEX86 values from surface sediments appear to correlate strongly with both annual mean as mean winter surface water temperatures. Besides this observed empirical relationship between TEX86 values and lake surface temperatures, very little is known about the distribution and ecology of the organisms that produce the lipids that make up the TEX86 in lacustrine systems. Here we will present the results of our multiyear water column and sediment trap study in Lake Superior where we investigated where vertically and at what time of year the lipids are produced that make up the TEX86 proxy, which end up in the sediment record. We have combined both biogeochemical and molecular techniques to both water filter samples as sediment trap material, combined thermistor observations in the water column to create vertical profiles of Crenarchaeotal and lipid abundance to investigate the spatial distribution of the lacustrine Crenarchaeota in order to determine if or what kind of temperature is actually represented by the TEX86 proxy in Lake Superior. Our results show that the TEX86 measured in particulate organic matter does a good job reconstructing the actual thermal structure of the water column. However, the lipids that make up the TEX86 in Lake Superior are produced throughout the lake during isothermal conditions, but mainly below the thermocline when the lake is stratified suggesting that in Lake Superior the TEX86 largely

  12. Bivariate spatial analysis of temperature and precipitation from general circulation models and observation proxies

    KAUST Repository

    Philbin, R.

    2015-05-22

    This study validates the near-surface temperature and precipitation output from decadal runs of eight atmospheric ocean general circulation models (AOGCMs) against observational proxy data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis temperatures and Global Precipitation Climatology Project (GPCP) precipitation data. We model the joint distribution of these two fields with a parsimonious bivariate Matérn spatial covariance model, accounting for the two fields\\' spatial cross-correlation as well as their own smoothnesses. We fit output from each AOGCM (30-year seasonal averages from 1981 to 2010) to a statistical model on each of 21 land regions. Both variance and smoothness values agree for both fields over all latitude bands except southern mid-latitudes. Our results imply that temperature fields have smaller smoothness coefficients than precipitation fields, while both have decreasing smoothness coefficients with increasing latitude. Models predict fields with smaller smoothness coefficients than observational proxy data for the tropics. The estimated spatial cross-correlations of these two fields, however, are quite different for most GCMs in mid-latitudes. Model correlation estimates agree well with those for observational proxy data for Australia, at high northern latitudes across North America, Europe and Asia, as well as across the Sahara, India, and Southeast Asia, but elsewhere, little consistent agreement exists.

  13. Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea

    Science.gov (United States)

    Fowell, Sara E.; Sandford, Kate; Stewart, Joseph A.; Castillo, Karl D.; Ries, Justin B.; Foster, Gavin L.

    2016-10-01

    Caribbean sea surface temperatures (SSTs) have increased at a rate of 0.2°C per decade since 1971, a rate double that of the mean global change. Recent investigations of the coral Siderastrea siderea on the Belize Mesoamerican Barrier Reef System (MBRS) have demonstrated that warming over the last 30 years has had a detrimental impact on calcification. Instrumental temperature records in this region are sparse, making it necessary to reconstruct longer SST records indirectly through geochemical temperature proxies. Here we investigate the skeletal Sr/Ca and Li/Mg ratios of S. siderea from two distinct reef zones (forereef and backreef) of the MBRS. Our field calibrations of S. siderea show that Li/Mg and Sr/Ca ratios are well correlated with temperature, although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef. These differences suggest that a secondary parameter also influences these SST proxies, highlighting the importance for site- and species-specific SST calibrations. Application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral, but well-matched reconstructed temperatures in forereef coral, both between Sr/Ca-SSTs and Li/Mg-SSTs, and in comparison to the Hadley Centre Sea Ice and Sea Surface Temperature record. Reconstructions generated from a combined Sr/Ca and Li/Mg multiproxy calibration improve the precision of these SST reconstructions. This result confirms that there are circumstances in which both Li/Mg and Sr/Ca are reliable as stand-alone and combined proxies of sea surface temperature. However, the results also highlight that high-precision, site-specific calibrations remain critical for reconstructing accurate SSTs from coral-based elemental proxies.

  14. Was the Little Ice Age more or less El Niño-like than the Medieval Climate Anomaly? Evidence from hydrological and temperature proxy data

    Science.gov (United States)

    Henke, Lilo M. K.; Lambert, F. Hugo; Charman, Dan J.

    2017-03-01

    The El Niño-Southern Oscillation (ENSO) is the most important source of global climate variability on interannual timescales and has substantial environmental and socio-economic consequences. However, it is unclear how it interacts with large-scale climate states over longer (decadal to centennial) timescales. The instrumental ENSO record is too short for analysing long-term trends and variability and climate models are unable to accurately simulate past ENSO states. Proxy data are used to extend the record, but different proxy sources have produced dissimilar reconstructions of long-term ENSO-like climate change, with some evidence for a temperature-precipitation divergence in ENSO-like climate over the past millennium, in particular during the Medieval Climate Anomaly (MCA; AD ˜ 800-1300) and the Little Ice Age (LIA; AD ˜ 1400-1850). This throws into question the stability of the modern ENSO system and its links to the global climate, which has implications for future projections. Here we use a new statistical approach using weighting based on empirical orthogonal function (EOF) to create two new large-scale reconstructions of ENSO-like climate change derived independently from precipitation proxies and temperature proxies. The method is developed and validated using model-derived pseudo-proxy experiments that address the effects of proxy dating error, resolution, and noise to improve uncertainty estimations. We find no evidence that temperature and precipitation disagree over the ENSO-like state over the past millennium, but neither do they agree strongly. There is no statistically significant difference between the MCA and the LIA in either reconstruction. However, the temperature reconstruction suffers from a lack of high-quality proxy records located in ENSO-sensitive regions, which limits its ability to capture the large-scale ENSO signal. Further expansion of the palaeo-database and improvements to instrumental, satellite, and model representations of

  15. Holocene seasonal variability inferred from multiple proxy records from Crevice Lake, Yellowstone National Park, USA

    Science.gov (United States)

    Whitlock, Cathy; Dean, Walter E.; Fritz, Sherilyn C.; Stevens, Lora R.; Stone, Jeffery R.; Power, Mitchell J.; Rosenbaum, Joseph R.; Pierce, Kenneth L.; Bracht-Flyr, Brandi B.

    2012-01-01

    A 9400-yr-old record from Crevice Lake, a semi-closed alkaline lake in northern Yellowstone National Park, was analyzed for pollen, charcoal, geochemistry, mineralogy, diatoms, and stable isotopes to develop a nuanced understanding of Holocene environmental history in a region of northern Rocky Mountains that receives both summer and winter precipitation. The limited surface area, conical bathymetry, and deep water (> 31 m) of Crevice Lake create oxygen-deficient conditions in the hypolimnion and preserve annually laminated sediment (varves) for much of the record. Pollen data indicate that the watershed supported a closed Pinus-dominated forest and low fire frequency prior to 8200 cal yr BP, followed by open parkland until 2600 cal yr BP, and open mixed-conifer forest thereafter. Fire activity shifted from infrequent stand-replacing fires initially to frequent surface fires in the middle Holocene and stand-replacing events in recent centuries. Low values of δ18O suggest high winter precipitation in the early Holocene, followed by steadily drier conditions after 8500 cal yr BP. Carbonate-rich sediments before 5000 cal yr BP imply warmer summer conditions than after 5000 cal yr BP. High values of molybdenum (Mo), uranium (U), and sulfur (S) indicate anoxic bottom-waters before 8000 cal yr BP, between 4400 and 3900 cal yr BP, and after 2400 cal yr BP. The diatom record indicates extensive water-column mixing in spring and early summer through much of the Holocene, but a period between 2200 and 800 cal yr BP had strong summer stratification, phosphate limitation, and oxygen-deficient bottom waters. Together, the proxy data suggest wet winters, protracted springs, and warm effectively wet summers in the early Holocene and less snowpack, cool springs, warm dry summers in the middle Holocene. In the late Holocene, the region and lake experienced extreme changes in winter, spring, and summer conditions, with particularly short springs and dry summers and winters during

  16. Reconstruction of Antarctic climate change using ice core proxy records from the coastal Dronning Maud Land, East Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Laluraj, C.M.; Naik, S.S.; Chaturvedi, A.

    with the proxy record of solar activity (sup (10) Be profile from a South Pole ice core), suggesting enhanced NO sub (3) – values during periods of reduced solar activity like the Dalton Minimum (approx. 1790-1830 AD) and Maunder Minimum (approx. 1640- 1710 AD...

  17. Comparison of 2010 Census Nonresponse Follow-Up Proxy Responses with Administrative Records Using Census Coverage Measurement Results

    Directory of Open Access Journals (Sweden)

    Mulry Mary H.

    2017-06-01

    Full Text Available The U.S. Census Bureau is currently conducting research on ways to use administrative records to reduce the cost and improve the quality of the 2020 Census Nonresponse Followup (NRFU at addresses that do not self-respond electronically or by mail. Previously, when a NRFU enumerator was unable to contact residents at an address, he/she found a knowledgeable person, such as a neighbor or apartment manager, who could provide the census information for the residents. This was called a proxy response. The Census Bureau’s recent advances in merging federal and third-party databases raise the question: Are proxy responses for NRFU addresses more accurate than the administrative records available for the housing unit? Our study attempts to answer this question by comparing the quality of proxy responses and the administrative records for those housing units in the same timeframe using the results of 2010 Census Coverage Measurement (CCM Program. The assessment of the quality of the proxy responses and the administrative records in the CCM sample of block clusters takes advantage of the extensive fieldwork, processing, and clerical matching conducted for the CCM.

  18. Data for evaluating the Sr/Ca temperature proxy with in-situ temperature in the western Atlantic coral Siderastrea siderea

    Science.gov (United States)

    Kuffner, Ilsa B.; Roberts, Kelsey E.; Flannery, Jennifer A.; Morrison, Jennifer M.; Richey, Julie

    2016-01-01

    Massive corals are used as environmental recorders throughout the tropics and subtropics to study environmental variability during time periods preceding ocean-observing instrumentation. However, careful testing of paleoproxies is necessary to validate the environmental-proxy record throughout a range of conditions experienced by the recording organisms. As part of the USGS Coral Reef Ecosystems Studies project (http://coastal.er.usgs.gov/crest/), we tested the hypothesis that the coral Siderastrea siderea faithfully records sea-surface temperature (SST) in the Sr/Ca record throughout the subtropical (Florida, USA) seasonal cycle along 350 km of reef tract. Coral samples were analyzed from thirty-nine corals growing in 3 to 4 m depth at Fowey Rocks (Biscayne National Park), Molasses Reef (Florida Keys National Marine Sanctuary, FKNMS), Sombrero Reef (FKNMS), and Pulaski Shoal (Dry Tortugas National Park). Temperatures were recorded with Onset® HOBO® Water Temp Pro V2 (U22-001) data loggers in duplicate at each site. Sr/Ca, Mg/Ca, calcification rate, and select underwater temperature data are provided here. The results of this experiment are interpreted in Kuffner et al. (in review). A larger temperature dataset, including the data provided here, is found in another data release Kuffner (2015), and a larger calcification-rate dataset is interpreted in Kuffner et al. (2013).Kuffner, I.B., K.E. Roberts, J.A. Flannery, J.M. Morrison, and J.N. Richey. In review. Fidelity of the Sr/Ca proxy in recording ocean temperature in the western Atlantic coral Siderastrea siderea.Kuffner, I.B., T.D. Hickey, and J.M. Morrison. 2013. Calcification rates of the massive coral Siderastrea siderea and crustose coralline algae along the Florida Keys (USA) outer-reef tract. Coral Reefs 32:987-997. http://link.springer.com/article/10.1007/s00338-013-1047-8Kuffner, I. B. (2015), Underwater temperature on off-shore coral reefs of the Florida Keys, U.S.A.: U.S. Geological Survey data

  19. Variability in Bias of Gridded Sea Surface Temperature Data Products: Implications for Seasonally Resolved Marine Proxy Reconstructions

    Science.gov (United States)

    Ouellette, G., Jr.; DeLong, K. L.

    2016-12-01

    Seasonally resolved reconstructions of sea surface temperature (SST) are commonly produced using isotopic ratios and trace elemental ratios within the skeletal material of marine organisms such as corals, coralline algae, and mollusks. Using these geochemical proxies to produce paleoclimate reconstructions requires using regression methods to calibrate the proxy to observed SST, ideally with in situ SST records that span many years. Unfortunately, the few locations with in situ SST records rarely coincide with the time span of the marine proxy archive. Therefore, SST data products are often used for calibration and they are based on MOHSST or ICOADS SST observations as their main SST source but use different algorithms to produce globally gridded data products. These products include the Hadley Center's HADSST (5º) and interpolated HADISST (1º), NOAA's extended reconstructed SST (ERSST; 2º), optimum interpolation SST (OISST; 1º), and the Kaplan SST (5º). This study assessed the potential bias in these data products at marine archive sites throughout the tropical Atlantic using in situ SST where it was available, and a high-resolution (4 km) satellite-based SST data product from NOAA Pathfinder that has been shown to closely reflect in situ SST for our locations. Bias was assessed at each site, and then within each data product across the region for spatial homogeneity. Our results reveal seasonal biases in all data products, but not for all locations and not of a uniform magnitude or season among products. We found the largest differences in mean SST on the order of 1-3°C for single sites in the Gulf of Mexico, and differences for regional mean SST bias were 0.5-1°C when sites in the Gulf of Mexico were compared to sites in the Caribbean Sea within the same data product. No one SST data product outperformed the others and no systematic bias was found. This analysis illustrates regional strengths and weaknesses of these data products, and serves as a

  20. Holocene Temperature Record of the North Antarctic Peninsula

    Science.gov (United States)

    Willmott, V.; Kim, J.; Domack, E. W.; Sinninghe Damsté, J. S.; Schouten, S.

    2009-12-01

    Because sea temperature plays a critical role not only on the stability of ice shelves and sea ice formation, but as well on the marine ecology of polar areas, a lot of effort has been placed to reconstruct the past climate using proxies from ice, marine and terrestrial records. However, it has been difficult to apply traditional paleoenvironmental proxies in polar areas because of problems that include insufficient dating of recovered sequences, complexities introduced by glacial activity (i.e. glacial erosion), sea-ice cover and poor calcium carbonate preservation. Despite these difficulties, some paleoenvironmental records have been obtained so far although paleotemperature records are still very scarce. The TEX86 (TetraEther indeX of lipids with 86 carbon atoms), is an organic-based paleothermomether (Schouten et al., 2002) based on the relative distribution of archaeal lipids (GDGTs) biosynthesized by marine Crenarchaeota, one of the main prokaryotes of today’s oceans. Although the use of TEX86 in polar areas may be promising because it can be measured in carbonate poor sediments, its global correlation with sea surface temperature (SST) (Kim et al., 2008) revealed that the relationship between TEX86 values and SSTs over the entire temperature range was non-linear, mainly because below 5°C, i.e. in the polar oceans, changes in TEX86 were relatively minor with temperature. Recently, we obtained new insights on the relation between isoprenoid GDGTs and SST in polar oceans using an extended core-top sediment dataset which has lead to a new GDGT index which minimizes the scatter at low temperatures. We applied this new index to obtain a detailed Holocene SST record from well dated sediment cores from the north western Antarctic Peninsula. Temperature ranges show absolute temperature estimates (between -1 and 6 °C) in agreement with present day temperature range, reaching warmer temperatures between 6 to 8 ky. Cooler temperatures of about 2 °C dominates the

  1. EOP TDRs (Temperature-Depth-Recordings) Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature-depth-recorders (TDRs) were attached to commercial longline and research Cobb trawl gear to obtain absolute depth and temperature measurement during...

  2. A high-resolution multi-proxy record of late Cenozoic environment change from central Taklimakan Desert, China

    OpenAIRE

    X Wang; Sun, D. H.; Wang, F; Li, B F; Wu, S.; Guo, F.; Li, Z. J.; Zhang, Y. B.; F. H. Chen

    2013-01-01

    The Taklimakan Desert in the Tarim Basin is the largest desert in Central Asia, and is regarded as one of the main dust sources to the Northern Hemisphere. Late Cenozoic sedimentary sequences with intercalated in-situ aeolian dune sands in this area preserve direct evidence for the Asian desertification. Herein, we report a high-resolution multi-proxy climatic record from the precise magnetostratigraphic dated Hongbaishan section in the central Taklimakan Desert. Our results...

  3. A high-resolution multi-proxy record of late Cenozoic environment change from central Taklimakan Desert, China

    OpenAIRE

    X Wang; Sun, D. H.; Wang, F; Li, B F; Wu, S.; Guo, F.; Li, Z. J.; Zhang, Y. B.; F. H. Chen

    2013-01-01

    The Taklimakan Desert in the Tarim Basin is the largest desert in Central Asia, and is regarded as one of the main dust sources to the Northern Hemisphere. Late Cenozoic sedimentary sequences with intercalated in-situ aeolian dune sands in this area preserve direct evidence for the Asian desertification. Herein, we report a high-resolution multi-proxy climatic record from the precise magnetostratigraphic dated Hongbaishan section in the central Taklimakan Desert. Our results show that ...

  4. Decade to centennial resolution hydrogen isotopic record of climate change from southern New England for the past 16 kyr: proxy validation and multi-proxy comparisons

    Science.gov (United States)

    Huang, Y.; Gao, L.; Hou, J.; Shuman, B. N.; Oswald, W.; Foster, D.

    2009-12-01

    Open system lakes in New England offer excellent archives of precipitation isotopic ratios that yield quantitative paleoclimate information. We have demonstrated previously from a lake sediment transect that hydrogen isotopic ratios of a middle-chain length fatty acid, behenic acid (BA), faithfully record precipitation isotopic ratios. We hypothesized that mid-chain n-alkyl lipids in these small lakes were primarily derived from aquatic plants that record lake water isotopic ratios. To test this hypothesis, we conducted systematic and extensive sampling of both terrestrial and aquatic plants over the past two years at two typical kettle hole lakes, Blood Pond and Rocky Pond, MA, and used a linear algebra approach to delineate percentage inputs of aquatic and terrestrial plant contributions to mid-chain n-alkyl lipids. Our results demonstrate that >92 % of the mid-chain n-alkyl lipids is derived from submerged and floating aquatic macrophytes. Our new data provide a solid basis for the application of behenic hydrogen isotopic ratios as a paleoclimate proxy from small lakes. We will present a decadal to centennial scale 16 kyr record of BA hydrogen isotopic ratios from Blood Pond, and will discuss the results in light of published pollen and lake level data. Overall, our hydrogen isotopic record is fully consistent with regional climate scenarios, including the distinctive warming at B-A events, abrupt cooling at YD event, and transition from glacial to Holcoene climate conditions. However, our high-solution isotopic data provides important new insights concerning abrupt regional climate variability. We demonstrate that the New England climate is exceptionally senstive to AMOC changes and solar forcing and that many of the abrupt climate fluctuations exert major impacts on terrestrial ecosystems, hydrology and lake levels.

  5. Testing the potential of bacterial branched tetraether membrane lipids as temperature proxy in peat and immature coal deposits

    Science.gov (United States)

    Weijers, J. W. H.; Steinmann, P.; Hopmans, E. C.; Basiliko, N.; Finkelstein, S. A.; Johnson, K. R.; Schouten, S.; Sinninghe Damsté, J. S.

    2012-04-01

    Branched glycerol dialkyl glycerol tetraether (brGDGT) membrane lipids occur ubiquitously in peat and soil. In soil, the degree of methylation and cyclisation of branched tetraethers (MBT index and CBT ratio, respectively) has shown to relate to both soil pH and annual mean air temperature (MAT). Using this relation, past annual MATs can be reconstructed by analysing brGDGTs in marine sediment records near large river outflows. More recently, the potential of this MBT/CBT proxy is also being explored in lakes. Despite being more abundant in peat than soils, however, the utility of the proxy has not yet been fully explored in peat records. Present day peat records generally extent back to the early Holocene, but if the MBT/CBT proxy were shown to be applicable in peat deposits, there is also potential to apply it to immature coal deposits like lignites, which could provide valuable snapshots of continental climate back to the early Cenozoic. Here results are presented of analyses of different peats in south eastern Canada, showing that the pH of peat along a nutrient gradient is rather well reflected by the CBT. Annual MAT reconstructions based on the MBT/CBT soil calibration, however, tend to overestimate measured MAT. This is also the case for peat analysed from the surface of Etang de la Gruère peat bog in the Swiss Jura Mountains. Along the 6m depth profile of this bog (~13ka), CBT-reconstructed pH is compared with in-situ measured pore water pH showing that the brGDGT composition does not reflect present-day in-situ conditions. Instead, it reflects a stratigraphic boundary between Carex and Sphagnum dominated peat at 4 m depth that is not present in the pore water profile, testifying to a 'fossil' nature of the brGDGTs down the peat bog. Analyses of three immature coals of the Argonne Premium Coal Series reveal that branched GDGTs are present in the most immature coal, the Beulah Zap lignite (Ro = 0.25%), and only just above detection limit in the Wyodak

  6. The Last Interglacial-Glacial cycle (MIS 5-2) re-examined based on long proxy records from central and northern Europe

    Science.gov (United States)

    Helmens, Karin F.

    2014-02-01

    Current multi-proxy studies on a long sediment sequence preserved at Sokli (N Finland), i.e. in the central area of Fennoscandian glaciations, are drastically changing classic ideas of glaciations, vegetation and climate in northern Europe during the Late Pleistocene. The sediments in the Sokli basin have escaped major glacial erosion due to non-typical bedrock conditions. In this review, the Sokli record is compared in great detail with other long proxy records from central, temperate and northern, boreal Europe. These comprise the classic records of La Grande Pile (E France) and Oerel (N Germany) and more recently obtained records from Horoszki Duże (E Poland) and Lake Yamozero (NW Russia). The focus of the review is on pollen, lithology and macrofossil- and insect-based temperature inferences. The long records are further compared with recent proxy data from nearby terrestrial sites as well as with the rapidly accumulating high-resolution proxy data from the ocean realm. The comparison allows a re-examination of the environmental history and climate evolution of the Last Interglacial-Glacial (LI-G) cycle (MIS 5-2). It shows that environmental and climate conditions during MIS 5 (ca 130-70 ka BP) were distinctly different from those during MIS 4-2 (ca 70-15 ka BP). MIS 5 is characterized by three long forested intervals (broadly corresponding to MIS 5e, 5c, 5a), both in temperate and northern boreal Europe. These mild periods were interrupted by two short, relatively cold and dry intervals (MIS 5d and 5b) with mountain-centered glaciation in Fennoscandia. Millennial scale climate events were superimposed upon these longer lasting climate fluctuations. The time interval encompassing MIS 4-2 shows open vegetation. It is characterized by two glacial maxima (MIS 4 and 2) with sub-continental scale glaciation over northern Europe and dry conditions in strongly continental eastern European settings. High amplitude climate oscillations of millennial duration

  7. El Niño impact on mollusk biomineralization-implications for trace element proxy reconstructions and the paleo-archeological record.

    Directory of Open Access Journals (Sweden)

    Alberto Pérez-Huerta

    Full Text Available Marine macroinvertebrates are ideal sentinel organisms to monitor rapid environmental changes associated with climatic phenomena. These organisms build up protective exoskeletons incrementally by biologically-controlled mineralization, which is deeply rooted in long-term evolutionary processes. Recent studies relating potential rapid environmental fluctuations to climate change, such as ocean acidification, suggest modifications on carbonate biominerals of marine invertebrates. However, the influence of known, and recurrent, climatic events on these biological processes during active mineralization is still insufficiently understood. Analysis of Peruvian cockles from the 1982-83 large magnitude El Niño event shows significant alterations of the chemico-structure of carbonate biominerals. Here, we show that bivalves modify the main biomineralization mechanism during the event to continue shell secretion. As a result, magnesium content increases to stabilize amorphous calcium carbonate (ACC, inducing a rise in Mg/Ca unrelated to the associated increase in sea-surface temperature. Analysis of variations in Sr/Ca also suggests that this proxy should not be used in these bivalves to detect the temperature anomaly, while Ba/Ca peaks are recorded in shells in response to an increase in productivity, or dissolved barium in seawater, after the event. Presented data contribute to a better understanding of the effects of abrupt climate change on shell biomineralization, while also offering an alternative view of bivalve elemental proxy reconstructions. Furthermore, biomineralization changes in mollusk shells can be used as a novel potential proxy to provide a more nuanced historical record of El Niño and similar rapid environmental change events.

  8. Bacterial tetraether membrane lipids in peat and coal: Testing the MBT-CBT temperature proxy for climate reconstruction

    NARCIS (Netherlands)

    Weijers, J.W.H.; Steinmann, P.; Hopmans, E.C.; Schouten, S.; Sinninghe Damsté, J.S.

    2011-01-01

    Peatlands are widespread and important natural archives of environmental change. Here we explore the potential of the recently introduced MBT-CBT proxy (methylation index and cyclisation ratio of branched tetraethers) to estimate past annual mean air temperature (MAT) based on the distribution of

  9. Bacterial tetraether membrane lipids in peat and coal: Testing the MBT-CBT temperature proxy for climate reconstruction

    NARCIS (Netherlands)

    Weijers, J.W.H.; Steinmann, P.; Hopmans, E.C.; Schouten, S.; Sinninghe Damsté, J.S.

    2011-01-01

    Peatlands are widespread and important natural archives of environmental change. Here we explore the potential of the recently introduced MBT–CBT proxy (methylation index and cyclisation ratio of branched tetraethers) to estimate past annual mean air temperature (MAT) based on the distribution of

  10. A multi-proxy palaeoecological and palaeoclimatic record within full glacial lacustrine deposits, western Tennessee, USA

    Science.gov (United States)

    Grimley, D.A.; Daniel, L.; Kaplan, S.W.; Yansa, C.H.; Curry, B. Brandon; Oches, E.A.

    2009-01-01

    The Fulton Section, along the Mississippi River in western Tennessee, USA, is a 1km continuous exposure (~20m vertically) of Quaternary fluvial and lacustrine deposits, inset within Eocene sediments and buried by thick loess. Fossiliferous slackwater lake sediments record maximum aggradation during the last two major glaciations, with deposition between ca. 190-140 ka and 24-1814C ka BP, based on amino acid and radiocarbon chronology, respectively. During the onset of full glacial conditions (ca. 24-22 14C ka BP), a relatively permanent shallow lake environment is indicated by ostracods, aquatic molluscs, and both pollen and macrofossils of aquatic plants. By 21.8 14C ka BP, increasing emergent plants, amphibious gastropods (Pomatiopsis) and heavier ??18O compositions suggest marsh-like conditions in a periodically drying lake. The surrounding uplands consisted of Picea-Pinus woodlands mixed with cool-temperate hardwoods (e.g. Quercus, Populus, Carya), grasses and herbs. More open conditions ensued ca. 20 14C ka BP, with loess and slopewash gradually infilling the former lake by 18 14C ka BP. Modern analogue analyses of ostracods and palaeontological evidence imply a full glacial climate similar to today's mixed-boreal zone in central Minnesota, USA, about 98C cooler in mean annual temperature than present-day western Tennessee. Copyright ?? 2009 John Wiley & Sons, Ltd.

  11. Past climate variability between 97 and 7 ka reconstructed from a multi proxy speleothem record from Western Cuba

    Science.gov (United States)

    Winterhalder, Sophie; Scholz, Denis; Mangini, Augusto; Spötl, Christoph; Jochum, Klaus Peter; Pajón, Jesús M.

    2016-04-01

    The tropical hydrological cycle plays a key role in regulating global climate, mainly through the export of heat and moisture to higher latitudes, and is highly sensitive to climate change, for instance due to changes in the position of the Intertropical Convergence Zone (ITCZ). Previous work on Caribbean stalagmites suggests a strong connection of precipitation variability to North Atlantic (NA) sea surface temperatures on multidecadal to millenial timescales (Fensterer et al., 2012; Fensterer et al., 2013; Winter et al., 2011). Cold phases in the NA potentially lead to a southward shift of the ITCZ and thus drier conditions in Cuba. On orbital timescales, Cuban stalagmites suggest a relation of speleothem δ18O values with the δ18O value of Caribbean surface waters (Fensterer et al., 2013). Here we present an expansion of the Cuban speleothem record covering the whole last glacial period from the end of MIS5c (97 ka BP) until 7 ka with hiatuses between 93-80 ka, 37-35 ka and 13-10 ka. Stalagmite Cuba medio (CM) has been precisely dated with 60 230Th/U-ages, mainly performed by the MC-ICPMS technique. The δ18O and δ13C records are completed by a continuous, high resolution LA-ICPMS trace element profile. These data allow for the first time to establish a multi-proxy climate reconstruction for the North Western Caribbean at decadal to centennial resolution for this period. The long-term variability of the δ18O values probably reflects rainfall amount in Cuba. The response to some Dansgaard/Oeschger and Heinrich stadials confirms the previously observed correlation between Caribbean and NA climate variability. However, this connection is not clearly imprinted throughout the record. Furthermore, trace elements, such as Mg, do not proof without ambiguity drier conditions in Cuba during NA cold events, such as the Heinrich stadials. This suggests that climate variability in Cuba was more complex during the last 100ka, and that the NA was not the only driving factor

  12. Record temperature streak bears anthropogenic fingerprint

    Science.gov (United States)

    Mann, Michael E.; Miller, Sonya K.; Rahmstorf, Stefan; Steinman, Byron A.; Tingley, Martin

    2017-08-01

    We use a previously developed semiempirical approach to assess the likelihood of the sequence of consecutive record-breaking temperatures in 2014-2016. This approach combines information from historical temperature data and state-of-the-art historical climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that this sequence of record-breaking temperatures had a negligible (at some point since 2000 is estimated as 30-50% given anthropogenic warming and <0.7% in its absence. The likelihood of observing the specific level of record warmth recorded during 2016 is no more than one-in-a-million neglecting anthropogenic warming, but as high as 27%, i.e., a nearly one-in-three chance of occurrence taking anthropogenic warming into account.

  13. Sr/Ca proxy sea-surface temperature reconstructions from modern and holocene Montastraea faveolata specimens from the Dry Tortugas National Park

    Science.gov (United States)

    Flannery, Jennifer A.; Poore, Richard Z.

    2013-01-01

    Sr/Ca ratios from skeletal samples from two Montastraea faveolata corals (one modern, one Holocene, ~6 Ka) from the Dry Tortugas National Park were measured as a proxy for sea-surface temperature (SST). We sampled coral specimens with a computer-driven triaxial micromilling machine, which yielded an average of 15 homogenous samples per annual growth increment. We regressed Sr/Ca values from resulting powdered samples against a local SST record to obtain a calibration equation of Sr/Ca = -0.0392 SST + 10.205, R = -0.97. The resulting calibration was used to generate a 47-year modern (1961-2008) and a 7-year Holocene (~6 Ka) Sr/Ca subannually resolved proxy record of SST. The modern M. faveolata yields well-defined annual Sr/Ca cycles ranging in amplitude from ~0.3 and 0.5 mmol/mol. The amplitude of ~0.3 to 0.5 mmol/mol equates to a 10-15°C seasonal SST amplitude, which is consistent with available local instrumental records. Summer maxima proxy SSTs calculated from the modern coral Sr/ Ca tend to be fairly stable: most SST maxima from 1961–2008 are 29°C ± 1°C. In contrast, winter minimum SST calculated in the 47-year modern time-series are highly variable, with a cool interval in the early to mid-1970s. The Holocene (~6 Ka) Montastraea faveolata coral also yields distinct annual Sr/Ca cycles with amplitudes ranging from ~0.3 to 0.6 mmol/mol. Absolute Sr/Ca values and thus resulting SST estimates over the ~7-year long record are similar to those from the modern coral. We conclude that Sr/Ca from Montastraea faveolata has high potential for developing subannually resolved Holocene SST records.

  14. Multiple water isotope proxy reconstruction of extremely low last glacial temperatures in Eastern Beringia (Western Arctic)

    NARCIS (Netherlands)

    Porter, Trevor J.; Froese, Duane G.; Feakins, Sarah J.; Bindeman, Ilya N.; Mahony, Matthew E.; Pautler, Brent G.; Reichart, Gert-Jan; Sanborn, Paul T.; Simpson, Myrna J.; Weijers, Johan W H

    2016-01-01

    Precipitation isotopes are commonly used for paleothermometry in high latitude regions. Here we present multiple water isotope proxies from the same sedimentary context - perennially frozen loess deposits in the Klondike Goldfields in central Yukon, Canada, representing parts of Marine Isotope

  15. A high-resolution multi-proxy record of late Cenozoic environment change from central Taklimakan Desert, China

    Science.gov (United States)

    Wang, X.; Sun, D. H.; Wang, F.; Li, B. F.; Wu, S.; Guo, F.; Li, Z. J.; Zhang, Y. B.; Chen, F. H.

    2013-12-01

    The Taklimakan Desert in the Tarim Basin is the largest desert in Central Asia, and is regarded as one of the main dust sources to the Northern Hemisphere. Late Cenozoic sedimentary sequences with intercalated in-situ aeolian dune sands in this area preserve direct evidence for the Asian desertification. Herein, we report a high-resolution multi-proxy climatic record from the precise magnetostratigraphic dated Hongbaishan section in the central Taklimakan Desert. Our results show that a fundamental climate change, characterised by significant cooling, enhanced aridity, and intensified atmospheric circulation, occurred at 2.8 Ma. Good correlations between paleo-environmental records in the dust sources and downwind areas suggest a broadly consistent climate evolution of northwestern China during the late Cenozoic, which is probably driven by the uplift of the Tibet Plateau and the Northern Hemisphere glaciation.

  16. Molecular proxies for paleoclimatology

    Science.gov (United States)

    Eglinton, Timothy I.; Eglinton, Geoffrey

    2008-10-01

    We summarize the applications of molecular proxies in paleoclimatology. Marine molecular records especially are proving to be of value but certain environmentally persistent compounds can also be measured in lake sediments, loess deposits and ice cores. The fundamentals of this approach are the molecular parameters, the compound abundances and carbon, hydrogen, nitrogen and oxygen isotopic contents which can be derived by the analysis of sediment extracts. These afford proxy measures which can be interpreted in terms of the conditions which control climate and also reflect its operation. We discuss two types of proxy; those of terrigenous and those of aquatic origin, and exemplify their application in the study of marine sediments through the medium of ten case studies based in the Atlantic, Mediterranean and Pacific Oceans, and in Antarctica. The studies are mainly for periods in the present, the Holocene and particularly the last glacial/interglacial, but they also include one study from the Cretaceous. The terrigenous proxies, which are measures of continental vegetation, are based on higher plant leaf wax compounds, i.e. long-chain (circa C 30) hydrocarbons, alcohols and acids. They register the relative contributions of C 3 vs. C 4 type plants to the vegetation in the source areas. The two marine proxies are measures of sea surface temperatures (SST). The longer established one, (U 37K') is based on the relative abundances of C 37 alkenones photosynthesized by unicellular algae, members of the Haptophyta. The newest proxy (TEX 86) is based on C 86 glycerol tetraethers (GDGTs) synthesized in the water column by some of the archaeal microbiota, the Crenarchaeota.

  17. Study of spectro-temporal variation in paleo-climatic marine proxy records using wavelet transformations

    Science.gov (United States)

    Pandey, Chhavi P.

    2017-10-01

    Wavelet analysis is a powerful mathematical and computational tool to study periodic phenomena in time series particu-larly in the presence of potential frequency changes in time. Continuous wavelet transformation (CWT) provides localised spectral information of the analysed dataset and in particular useful to study multiscale, nonstationary processes occurring over finite spatial and temporal domains. In the present work, oxygen-isotope ratio from the plantonic foraminifera species (viz. Globigerina bul-loides and Globigerinoides ruber) acquired from the broad central plateau of the Maldives ridge situated in south-eastern Arabian sea have been used as climate proxy. CWT of the time series generated using both the biofacies indicate spectro-temporal varia-tion of the natural climatic cycles. The dominant period resembles to the period of Milankovitch glacial-interglacial cycle. Apart from that, various other cycles are present in the time series. The results are in good agreement with the astronomical theory of paleoclimates and can provide better visualisation of Indian summer monsoon in the context of climate change.

  18. Late Glacial to Holocene abrupt temperature changes recorded by Crenarchaeota in Lake Lucerne (Vierwaldstättersee, Switzerland)

    Science.gov (United States)

    Blaga, Cornelia I.; Reichart, Gert-Jan; Lotter, André F.; Anselmetti, Flavio; Sinninghe Damsté, Jaap S.

    2010-05-01

    In this study we applied the TEX86 (TetraEther Index of 86 carbon atoms) temperature proxy to a sediment core from Lake Lucerne (Vierwaldstättersee) to reconstruct, in almost decadal resolution, temperature changes during the Younger Dryas and the Early Holocene (ca. 14600 to 10600 cal. BP). The TEX86 proxy suggests a sequence of shifts during the late glacial period that strongly resemble the shifts in δ18O values from the Greenland ice core record. The TEX86-reconstructed lake temperature record indicates a step-wise pattern of climate changes across the studied interval with a shift from colder to warmer temperatures at the onset of the late-glacial interstadial, followed by an abrupt cooling at the onset of Younger Dryas and a rapid warming from 5.5 to 9°C at the Younger Dryas/Holocene transition in less than 200 years. The temperature change associated with the Interstadial-Younger Dryas alternation is ca. 4 °C and is in line with previous temperature reconstructions based on different proxies. The rapid changes in temperature associated with the last deglaciation are reflected in the highest possible detail in the TEX86 record. It is thus clear that our proxy, based on the isoprenoidal GDGTs (Glycerol Dialkyl Glycerol Tetraethers), is capable to reflect high resolution records of rapid (decadal to century scale oscillations) environmental fluctuations comparable with those obtained from ice cores.

  19. A multi-proxy record of volume in the Great Salt Lake over the Holocene

    Science.gov (United States)

    Nielson, K. E.; Bowen, G. J.; Toney, J. L.; Tarozo, R.; Huang, Y.; Bowen, B.

    2010-12-01

    Continental paleoclimate records for the Holocene are essential for understanding the influence of climate modes on terrestrial settings. Terminal lakes, like the Great Salt Lake, UT (GSL) are particularly well suited for examining changes in water balance in response to large scale climate change. We present records of lipid abundance and hydrogen isotope data; hydrogen and oxygen isotope variability in brine shrimp cysts; carbonate oxygen and carbon isotopes; and variability in mineralogy from reflectance spectrometry in a core spanning 9 to 2 ka bp from the GSL. The isotopic value of lake waters are inferred from the cyst isotope records. The oxygen isotopic composition of cysts decreases slowly by about 2 ‰ from the beginning of the record (approx. 9 ka bp) to about 6 ka, and is highly variable after about 4.5 ka bp. This gradual isotopic decrease suggests increased water input into the GSL up to the Mid-Holocene and more variable inputs after. Some portion of the decrease is likely attributable to a reestablishment of equilibrium with local precipitation sources following the rapid evaporation of Lake Bonneville at the end of the Pleistocene. Carbonate oxygen and carbon isotope ratios co-vary before 5.5 ka and after 4.5 ka, and are anti-correlated between, suggesting a major restructuring of the hydrologic regime in the Mid-Holocene. Distributions of lipid and n

  20. Phanerozoic pCO2 recorded by the plants that used it: refinement, independent validation and multi-proxy comparison of a physiological model.

    Science.gov (United States)

    Franks, P.; Royer, D. L.; Kowalczyk, J.; Milligan, J.

    2016-12-01

    CO2 has been described as the most important greenhouse gas in terms of maintaining a habitable climate on Earth. However, pCO2 has not been constant through time and the resulting variability of its forcing has contributed to periodic swings in global climate between warmer and cooler periods. Reliable prediction of the magnitude and effects of future global warming with increasing pCO2 depends on quantifying climate sensitivity to forcing by pCO2, which can only be measured from the record of pCO2 and temperature in Earth's geological past. This has been difficult because of inherent uncertainties, sometimes unquantifiable, in the reconstruction of pCO2 for past geologic periods. Recently a new CO2 proxy was developed based on the principle that photosynthesis by plants is quantitatively dependent on pCO2 (CO2 being the substrate for photosynthesis), with the record of this relationship preserved in the structure and chemistry of plant fossils (Franks et al., 2014, Geophysical Research Letters, 41: 4685-4694). This method has constrained uncertainty to more moderate bounds and eliminated instances of unbounded uncertainty. Here we describe a refinement to one of the input physiological quantities, the present-day ratio of intercellular to ambient CO2 concentration, ci/ca, which improves model accuracy. We also summarise the key findings of an independent validation and multi proxy comparison of the model using fossil plant material from a floristically diverse early Paleocene site which, at 64.5 Ma, was living 1.5 m.y after the Cretaceous-Paleogene boundary (KPB) mass extinction event. Principal amongst these findings is an upward revision of pCO2 to a median 612 ppm for the early Paleocene, with a corresponding minimum average Earth system sensitivity of 3.8 °C.

  1. Sea salt sodium record from Talos Dome (East Antarctica) as a potential proxy of the Antarctic past sea ice extent.

    Science.gov (United States)

    Severi, M; Becagli, S; Caiazzo, L; Ciardini, V; Colizza, E; Giardi, F; Mezgec, K; Scarchilli, C; Stenni, B; Thomas, E R; Traversi, R; Udisti, R

    2017-06-01

    Antarctic sea ice has shown an increasing trend in recent decades, but with strong regional differences from one sector to another of the Southern Ocean. The Ross Sea and the Indian sectors have seen an increase in sea ice during the satellite era (1979 onwards). Here we present a record of ssNa(+) flux in the Talos Dome region during a 25-year period spanning from 1979 to 2003, showing that this marker could be used as a potential proxy for reconstructing the sea ice extent in the Ross Sea and Western Pacific Ocean at least for recent decades. After finding a positive relationship between the maxima in sea ice extent for a 25-year period, we used this relationship in the TALDICE record in order to reconstruct the sea ice conditions over the 20th century. Our tentative reconstruction highlighted a decline in the sea ice extent (SIE) starting in the 1950s and pointed out a higher variability of SIE starting from the 1960s and that the largest sea ice extents of the last century occurred during the 1990s. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Using Proxy Records to Document Gulf of Mexico Tropical Cyclones from 1820-1915.

    Science.gov (United States)

    Pino, Jordan V; Rohli, Robert V; DeLong, Kristine L; Harley, Grant L; Trepanier, Jill C

    2016-01-01

    Observations of pre-1950 tropical cyclones are sparse due to observational limitations; therefore, the hurricane database HURDAT2 (1851-present) maintained by the National Oceanic and Atmospheric Administration may be incomplete. Here we provide additional documentation for HURDAT2 from historical United States Army fort records (1820-1915) and other archived documents for 28 landfalling tropical cyclones, 20 of which are included in HURDAT2, along the northern Gulf of Mexico coast. One event that occurred in May 1863 is not currently documented in the HURDAT2 database but has been noted in other studies. We identify seven tropical cyclones that occurred before 1851, three of which are potential tropical cyclones. We corroborate the pre-HURDAT2 storms with a tree-ring reconstruction of hurricane impacts from the Florida Keys (1707-2009). Using this information, we suggest landfall locations for the July 1822 hurricane just west of Mobile, Alabama and 1831 hurricane near Last Island, Louisiana on 18 August. Furthermore, we model the probable track of the August 1831 hurricane using the weighted average distance grid method that incorporates historical tropical cyclone tracks to supplement report locations.

  3. Using Proxy Records to Document Gulf of Mexico Tropical Cyclones from 1820-1915

    Science.gov (United States)

    Rohli, Robert V.; DeLong, Kristine L.; Harley, Grant L.; Trepanier, Jill C.

    2016-01-01

    Observations of pre-1950 tropical cyclones are sparse due to observational limitations; therefore, the hurricane database HURDAT2 (1851–present) maintained by the National Oceanic and Atmospheric Administration may be incomplete. Here we provide additional documentation for HURDAT2 from historical United States Army fort records (1820–1915) and other archived documents for 28 landfalling tropical cyclones, 20 of which are included in HURDAT2, along the northern Gulf of Mexico coast. One event that occurred in May 1863 is not currently documented in the HURDAT2 database but has been noted in other studies. We identify seven tropical cyclones that occurred before 1851, three of which are potential tropical cyclones. We corroborate the pre-HURDAT2 storms with a tree-ring reconstruction of hurricane impacts from the Florida Keys (1707–2009). Using this information, we suggest landfall locations for the July 1822 hurricane just west of Mobile, Alabama and 1831 hurricane near Last Island, Louisiana on 18 August. Furthermore, we model the probable track of the August 1831 hurricane using the weighted average distance grid method that incorporates historical tropical cyclone tracks to supplement report locations. PMID:27898726

  4. Ecology of lacustrine Crenarchaeota in Lake Superior: Implications for the application of the TEX86 temperature proxy

    Science.gov (United States)

    Woltering, M.; Werne, J.; Hicks, R.; Kish, J.; Schouten, S.; Sinninghe Damsté, J.

    2008-12-01

    The TEX86 paleotemperature proxy, based on tetraether membrane lipids derived from aquatic Crenarchaeota has been applied in a variety of marine and lacustrine systems. A recent study analyzing a suite of 50 globally distributed lakes for TEX86 discovered that this proxy does not appear to work in all lake systems and that the TEX86 correlates well with both annual and winter lake surface water temperature in those systems where it does appear to work. Besides this observed empirical relationship between TEX86 values and lake surface temperatures, very little is known about the ecology of the crenarchaeota in lakes. We combined both biogeochemical and molecular techniques in a multiyear study of Lake Superior using both sediment trap collection of settling particulate matter over the annual cycle and filtration of suspended particulate matter from lake water to create vertical profiles of crenarchaeotal cell numbers and lipid concentrations to investigate the spatial and temporal ecology of the lacustrine Crenarchaeota. Initial results show that the flux of the tetraether lipids is highly seasonal and mainly occurs during two time periods in winter and spring. The flux-weighted TEX86-derived temperatures from the sediment trap material agrees with the TEX86 temperature from a sediment core top from the sampling site and mixed water temperatures during the two periods of highest flux within the error of the method. Spatially, lipids used in TEX86 are found throughout the water column when the Lake Superior is isothermal, but mainly in the hypolimnion when the lake is stratified. During stratification tetraether lipids in the eplimnion appear to reflect a surface water temperature, while the more abundant tetraether lipids in the hypolimnion reflect a deep water temperature. These data suggest that the TEX86 in sediments of Lake Superior mainly reflect the water temperatures of times of highest lipid flux, mixed with a smaller portion of lipids that are mainly

  5. Reconstruction of Indian summer monsoon winds and precipitation over the past 10,000 years using equatorial pacific SST proxy records

    Science.gov (United States)

    Gill, Emily C.; Rajagopalan, Balaji; Molnar, Peter H.; Kushnir, Yochanan; Marchitto, Thomas M.

    2017-02-01

    Using a multiproxy reduced dimension methodology, we reconstruct fields of Arabian Sea summer wind stress curl and Indian monsoon rainfall anomalies since early Holocene using sea surface temperature (SST) proxies (Mg/Ca and alkenones) from 27 locations scattered across the equatorial Pacific. Reconstructions of summer wind stress curl reveal positive anomalies of ˜30% greater than present day off the coastlines of Oman and Yemen at 10 ka, suggesting enhanced ocean upwelling and an enhanced monsoon jet during this time. Positive wind stress curl anomalies in these regions continued but weakened to ˜12% greater than present day at 6 ka. Wind stress curl anomalies increased by about 8% from 6 to 4 ka but declined again until 2 ka. Positive anomalies in wind stress curl during the early to middle Holocene are consistent with greater early Holocene abundances of the upwelling indicator Globigerina bulloides in the western Arabian Sea, which accumulates most rapidly in present climates during periods of marked upwelling. Spatial rainfall reconstructions reveal the greatest difference in precipitation at 10 ka over the core monsoon region (˜20-60% greater than present day) and concurrently the greatest deficit in rainfall in North East India and on the eastern side of the Western Ghats (˜10-30% less than present day). Specifically, reconstructions for 10 ka reveal 40-60% greater rainfall than present day over northwest India. These findings advance the hypothesis that teleconnections from the equatorial Pacific contributed to, if not accounted for, greater early to middle Holocene wetness over India as recorded by various (e.g., cave, lacustrine, and discharge) paleoclimate proxies throughout the monsoon region.

  6. Des-A-lupane in an East African lake sedimentary record as a new proxy for the stable carbon isotopic composition of C3 plants

    NARCIS (Netherlands)

    van Bree, Loes G.J.; Rijpstra, W. Irene C; Al-Dhabi, N.A.; Verschuren, D.; Sinninghe Damste, J.S.; de Leeuw, J.W.

    2016-01-01

    We studied the high-resolution and well-dated 25,000 year sedimentary record of Lake Challa, a deep tropical crater lake in equatorial East Africa, to explore new proxies for paleoenvironmental and paleohydrological change. Sedimentary biomarker analysis revealed the presence of des-A-triterpenoids

  7. Alberta oil sands community exposure and health effects assessment : analysis of health records as a proxy for health outcomes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, F.; Mackenzie, A.; Schopflocher, D.; Shaw, S.; Robb, J.; Gabos, S. [Alberta Health and Wellness, Edmonton, AB (Canada)

    2002-07-01

    A large scale study was conducted to assess potential links between air quality and human health outcomes. Health records were used as a proxy measure for health outcomes. Residents of Fort McMurray and Lethbridge, Alberta, Canada were used in the comparison of risks of selected morbidity and mortality measures during a 3 year period between 1995 and 1998. Data on the socio-demography, morbidity, and mortality were linked by PI and geographic area from the Health Care Insurance Plan, physical and hospital billing systems, and vital statistics death registration. Age was the most important confounder. Asthma incidence for children 3 years or less was examined along with prevalence and mortality of selected diseases for each sex and age group. Results showed that the incidence of asthma varied by age and sex but not by study area. There was no major difference in death from lung cancer, cardiovascular disease, coronary heart disease, respiratory disorders and COPD between residents of the target and control communities. 6 figs.

  8. A multi-proxy record of MIS 11-12 deglaciation and glacial MIS 12 instability from the Sulmona basin (central Italy)

    Science.gov (United States)

    Regattieri, Eleonora; Giaccio, Biagio; Galli, Paolo; Nomade, Sebastien; Peronace, Edoardo; Messina, Paolo; Sposato, Andrea; Boschi, Chiara; Gemelli, Maurizio

    2016-01-01

    A multi-proxy record (lithology, XRF, CaCO3 content, carbonate δ18O and δ13C) was acquired from a sediment core drilled in the intermountain Sulmona basin (central Italy). Tephrostratigraphic analyses of three volcanic ash layers ascribe the investigated succession to the MIS 12-MIS 11 period, spanning the interval ca. 500-410 ka. Litho-pedo facies assemblage indicates predominant lacustrine deposition, interrupted by a minor sub-aerial and lake low stand episode. Variations in major and minor elements concentrations are related to changes in the clastic input to the lake. The oxygen isotopic composition of carbonate (δ18Oc) intervals is interpreted mainly as a proxy for the amount of precipitation in the high-altitude catchment of the karst recharge system. The record shows pronounced hydrological variability at orbital and millennial time-scales, which appears closely related to the Northern Hemisphere summer insolation pattern and replicates North Atlantic and west Mediterranean Sea Surface Temperature (SST) fluctuations. The MIS 12 glacial inception is marked by an abrupt reduction of precipitation, lowering of the lake level and enhanced catchment erosion. A well-defined and isotopically prominent interstadial with increased precipitation maybe related to insolation maxima-precession minima at ca. 465 ka. This interstadial ends abruptly at ca. 457 ka and it is followed by a phase of strong short-term instability. Drastic lake-level lowering and enhanced clastic flux characterized the MIS 12 glacial maximum. Lacustrine deposition restarted about 440 ka ago. The MIS 12-MIS 11 transition is characterized by a rapid increase in the precipitation, lake-level rise and reduction in the clastic input, interrupted by a short and abrupt return to drier conditions. Comparison with marine records from the Iberian margin and western Mediterranean suggests that major events of ice rafted debris deposition, related to southward migrations of the polar front, match the

  9. Multi-proxy record of land use change derived from colluvial soils of the western Pyrenees Mountains, France

    Science.gov (United States)

    Leigh, David S.; Gragson, Theodore L.; Coughlan, Michael R.

    2016-04-01

    Archaeological evidence and paleoenvironmental proxies from wetland bogs (e.g. charcoal, pastoral pollen, fungal spores of sheep dung) clearly outline the regional chronology of Holocene pastoral activity in the Pyrenees. We increase the spatial and temporal resolution of this chronology through a place-based, millennial-scale investigation of land use activities within individual fields in the commune of Larrau, Pyrénées Atlantiques, France. We have identified several stratigraphic records of slopewash colluvium that span the entire Holocene that occur at the outlets of zero-order watersheds, each draining several hectares. To examine forest-to-pasture transformation, two to three meter long auger holes were sampled in contiguous five centimeter intervals. These samples were analyzed for charcoal content, radiocarbon age, magnetic susceptibility, particle size, organic matter, and n-alkane concentrations. Results indicate that intentional burning and clearing were initiated by the Late Neolithic (ca. 5000-6000 cal. BP), but more intense burning, clearing, and pronounced soil erosion occurred later during the Bronze Age and Iron Age. Charcoal concentrations and low frequency magnetic susceptibility provide evidence of initial burning and subsequent variation in the intensity of fire use. Radiocarbon chronologies exhibit order-of-magnitude spikes in sedimentation rates (1-10 mm/yr) during the Bronze Age and Iron Age that are asynchronous between sites. Asynchronous records suggest anthropic, rather than climatic, drivers and imply that land use varied in intensity across the landscape, unlike the uniform intensity of pasture use typical of the modern landscape. Sedimentation rates, and presumably erosion rates, returned to very near pre-pastoral background levels (pastures around the world persist with stereotypical degraded soils. N-alkane analyses are in progress, testing for changes in past vegetation communities (trees vs. grass), and we anticipate results and

  10. Multiple oscillations during the Lateglacial as recorded in a multi-proxy, high-resolution record of the Moervaart palaeolake (NW Belgium)

    Science.gov (United States)

    Bos, Johanna A. A.; De Smedt, Philippe; Demiddele, Hendrik; Hoek, Wim Z.; Langohr, Roger; Marcelino, Vera; Van Asch, Nelleke; Van Damme, Dirk; Van der Meeren, Thijs; Verniers, Jacques; Boeckx, Pascal; Boudin, Mathieu; Court-Picon, Mona; Finke, Peter; Gelorini, Vanessa; Gobert, Stefan; Heiri, Oliver; Martens, Koen; Mostaert, Frank; Serbruyns, Lynn; Van Strydonck, Mark; Crombé, Philippe

    2017-04-01

    This paper presents the results of multi-disciplinary research carried out on the deposits of Moervaart depression, NW Belgium, one of the largest palaeolakes (∼25 km2) that existed during the Lateglacial interstadial in NW Europe. The multi-proxy study, including physical (organic matter and calcium carbonate, magnetic susceptibility, micromorphological), botanical (pollen, macrofossils, diatoms), zoological (ostracods, molluscs, chironomids) and chemical analyses (stable carbon and oxygen isotopes) has resulted in a detailed reconstruction of the Lateglacial landscape as well of the local conditions that prevailed in the lake itself. A chronology of the record was provided by radiocarbon dating and comparison with radiocarbon dates of the nearby Rieme site. These yielded a good match with the regional biostratigraphy. During the Lateglacial, vegetation and geomorphology of the landscape in general changed from a tundra landscape to a boreal forest. The vegetation development, however, was interrupted by a number of cold reversals. Three centennial-scale cold oscillations are present in the record: 1) the so-called Older Dryas corresponding to GI-1d in the Greenland ice-cores, 2) a short and pronounced cold event during the early Allerød, which could be correlated to GI-1c2 and 3) a cooling event during the late Allerød probably corresponding to the Intra Allerød Cold Period (IACP) or GI-1b. The latter most likely was responsible for the disappearance of the Moervaart palaeolake.

  11. Wet and cold climate conditions recorded by coral geochemical proxies during the beginning of the first millennium CE in the northern South China Sea

    Science.gov (United States)

    Xiao, Hangfang; Deng, Wenfeng; Chen, Xuefei; Wei, Gangjian; Zeng, Ti; Zhao, Jian-xin

    2017-03-01

    The past two millennia include some distinct climate intervals, such as the Medieval Warm Period (MWP) and the Little Ice Age (LIA), which were caused by natural forcing factors, as well as the Current Warm Period (CWP) that has been linked to anthropogenic factors. Therefore, this period has been of great interest to climate change researchers. However, most studies are based on terrestrial proxy records, historical documentary data, and simulation results, and the ocean and the tropical record are very limited. The Eastern Han, Three Kingdoms, and Western Jin periods (25-316 CE) cover the beginning first millennium CE in China, and were characterized by a cold climate and frequent wars and regime changes. This study used paired Sr/Ca and δ18O series recovered from a fossil coral to reconstruct the sea surface water conditions during the late Eastern Han to Western Jin periods (167-309 CE) at Wenchang, eastern Hainan Island in the northern South China Sea (SCS), to investigate climate change at this time. The long-term sea surface temperature (SST) during the study interval was 25.1 °C, which is about 1.5 °C lower than that of the CWP (26.6 °C). Compared with the average value of 0.40‰ during the CWP, the long-term average seawater δ18O (-0.06‰) was more negative. These results indicate that the climate conditions during the study period were cold and wet and comparable with those of the LIA. This colder climate may have been associated with the weaker summer solar irradiance. The wet conditions were caused by the reduced northward shift of the intertropical convergence zone/monsoon rainbelt associated with the retreat of the East Asian summer monsoon. Interannual and interdecadal climate variability may also have contributed to the variations in SST and seawater δ18O recorded over the study period.

  12. Nonlinear Shifts in Arctic Climate since the Holocene Thermal Maximum Recorded in a New High-Resolution Proxy Record from Otter Lake, South-Central Alaska

    Science.gov (United States)

    Bochicchio, C. J.; Yu, Z.

    2011-12-01

    Many paleoclimatic records show a gradual, near-linear cooling trend across the northern hemisphere since the Holocene Thermal Maximum, in response to an orbitally-driven gradual decline in summer insolation during the Holocene. Contrary to insolation trends, a few high-resolution records from high northern latitudes appear to indicate abrupt shifts in climate mean states. This suggests that Earth's climate system is capable of "step-like" transitions initiated when insolation thresholds are crossed and strong climatic feedbacks are triggered. In order to better understand the extent of possible nonlinear responses and forcing mechanisms, more high-resolution climate records are needed. In particular, records from Arctic regions are especially useful because Arctic climate feedbacks are stronger than in lower latitude regions and are well-documented. Here we present a multi-proxy record from a 4.8-m-long sediment core collected from Otter Lake, a small perched, precipitation- and groundwater-fed marl (carbonate-rich) lake (~300 m2 surface area, ~7 m depth), in south-central Alaska. The lake was formed more than 14,000 years ago after ice retreat. We combined a modern calibration study utilizing the relationship between lake depth and sediment composition along water-depth transects with down-core analysis of sedimentary proxies to reconstruct Holocene lake-level. We found three distinct periods of sedimentation: (1) the early Holocene: predominately carbonate-rich sediments (~70%) with low variability in sediment composition; (2) mid-Holocene: organic-rich sediments with low carbonate content (~20%) and very low variability; and (3) late Holocene: high average carbonate content (~50%) with the greatest variability in sediment composition (between 10% and 66% carbonate). We interpret the change in sediment composition to reflect lake-level change, with high carbonate content corresponding to shallow water, as observed from analysis of modern sediments. Therefore

  13. Pathfinder Sea Surface Temperature Climate Data Record

    Science.gov (United States)

    Baker-Yeboah, S.; Saha, K.; Zhang, D.; Casey, K. S.

    2016-02-01

    Global sea surface temperature (SST) fields are important in understanding ocean and climate variability. The NOAA National Centers for Environmental Information (NCEI) develops and maintains a high resolution, long-term, climate data record (CDR) of global satellite SST. These SST values are generated at approximately 4 km resolution using Advanced Very High Resolution Radiometer (AVHRR) instruments aboard NOAA polar-orbiting satellites going back to 1981. The Pathfinder SST algorithm is based on the Non-Linear SST algorithm using the modernized NASA SeaWiFS Data Analysis System (SeaDAS). Coefficients for this SST product were generated using regression analyses with co-located in situ and satellite measurements. Previous versions of Pathfinder included level 3 collated (L3C) products. Pathfinder Version 5.3 includes level 2 pre-processed (L2P), level 3 Uncollated (L3C), and L3C products. Notably, the data were processed in the cloud using Amazon Web Services and are made available through all of the modern web visualization and subset services provided by the THREDDS Data Server, the Live Access Server, and the OPeNDAP Hyrax Server.In this version of Pathfinder SST, anomalous hot-spots at land-water boundaries are better identified and the dataset includes updated land masks and sea ice data over the Antarctic ice shelves. All quality levels of SST values are generated, giving the user greater flexibility and the option to apply their own cloud-masking procedures. Additional improvements include consistent cloud tree tests for NOAA-07 and NOAA-19 with respect to the other sensors, improved SSTs in sun glint areas, and netCDF file format improvements to ensure consistency with the latest Group for High Resolution SST (GHRSST) requirements. This quality controlled satellite SST field is a reference environmental data record utilized as a primary resource of SST for numerous regional and global marine efforts.

  14. Late Holocene environmental change and human impact inferred from three soil monoliths and the Laguna Zurita multi-proxi record in the southeastern Ecuadorian Andes

    OpenAIRE

    Niemann, Holger; Behling,Hermann

    2009-01-01

    Late Holocene vegetation, climate and fire dynamics of mountain forest and paramo ecosystems, as well as human impact, are presented from the upper Rio San Francisco valley, southeastern Ecuadorian Andes. Palaeoenvironmental changes, inferred from three soil monoliths, spanning an altitudinal gradient between 1,990 and 3,200 m and the high resolution multi-proxy sediment record from Laguna Zurita (2,590 m), were investigated by pollen, spore and charcoal analyses, in combination with XRF- and...

  15. A 4500-year ostracod record from Lake Shkodra (Albania): palaeoenvironmental and palaeoclimatic reconstruction using a multi proxy approach.

    Science.gov (United States)

    Mazzini, Ilaria; Gliozzi, Elsa; Koci, Rexhep; Zanchetta, Giovanni; Baneschi, Ilaria; Sadori, Laura; Giardini, Marco; Van Welden, Aurelien; Bushati, Salvatore

    2013-04-01

    values between ca. -8.7‰ and - 6.4‰, with frequent and large fluctuations from 4500 to ca 1200 cal a BP; such fluctuations decrease after ca 1200 cal a BP and at ca 800 cal a BP the values attain close to ca. -7.2 ‰. The δ13Cc record display value ranges between between ca. -5.1‰ and -3.1‰, the highest values are recorded between 4500 and 3000 cal a BP and the lowest peak is reached at about 1200 cal a BP following which there is an increasing trend reaching stability around -3.7‰ from 700 cal a BP. The pollen record is quite homogeneous, however since ca 1100 cal a BP the percentage of arboreal pollen decreases together with the pollen concentrations. Surprisingly most of the ostracod and charophyte species occur in recent material, sampled between 2010 and 2011 in the Albanian side of the lake. The drastic change recorded by all proxies at around 1200 cal a BP could be related to favourable climatic conditions linked to the Medieval Warm Period as recorded in other Mediterranean lakes. But a more local signal could have been the trigger for the sudden increase in ostracod frequencies, the disappearance of charophytes and the progressive magnitude reduction of the δ18Oc excursions recorded after 1200 cal a BP. could be also linked to a change in land use due to human activities. Because of its high sedimentation rate, the high authigenic carbonate component, the abundant and well preserved microfossils and the possibility to study the modern analogue, the Shkodra lake and the SK13 composite core represent a perfect opportunity to study the Holocene evolution of an area at the transition between the Mediterranean Basin and the Balkans. References Sulpizio R., van Welden A., Caron B. & Zanchetta G. (2010) - The Holocene tephrostratigraphic record of Lake Shkodra (Albania and Montenegro). Journal of Quaternary Science, 25, 633-650. Van Welden A., BeckC., ReyssJ.L., Bushati S., Koci R., Jouanne F. & Mugnier J.L. (2008) - The last 500 year of sedimentation in

  16. Cueva Antón: A multi-proxy MIS 3 to MIS 5a paleoenvironmental record for SE Iberia

    Science.gov (United States)

    Zilhão, João; Ajas, Aurélie; Badal, Ernestina; Burow, Christoph; Kehl, Martin; López-Sáez, José Antonio; Pimenta, Carlos; Preece, Richard C.; Sanchis, Alfred; Sanz, Montserrat; Weniger, Gerd-Christian; White, Dustin; Wood, Rachel; Angelucci, Diego E.; Villaverde, Valentín; Zapata, Josefina

    2016-08-01

    Overlying a palustrine deposit of unknown age (complex FP), and protected from weathering and erosion inside a large cave/rock-shelter cavity, the sedimentary fill of Cueva Antón, a Middle Paleolithic site in SE Spain, corresponds in most part (sub-complexes AS2-to-AS5) to a ca.3 m-thick Upper Pleistocene terrace of the River Mula. Coupled with the constraints derived from the deposit's paleoclimatic proxies, OSL dating places the accumulation of this terrace in MIS 5a, and radiocarbon dates from the overlying breccia cum alluvium (sub-complex AS1) fall in the middle part of MIS 3; the intervening hiatus relates to valley incision and attendant erosion. The two intervals represented remain largely unknown in Iberia, where the archeology of the early-to-middle Upper Pleistocene is almost entirely derived from karst sites; Cueva Antón shows that this dearth of data, often interpreted in demographic terms, has depositional underpinnings ultimately determined by past climate variation. In early MIS 5a, the paleobotanical evidence indicates climate conditions similar to present, albeit wetter, followed by progressive cooling, reflected in the replacement of Aleppo pine by black pine and, at the very end, juniper-dominated landscapes - the latter characterizing also mid-MIS 3 times. The variation in sedimentary facies and composition of the mollusk assemblages reflects the changing position of the river channel relative to the back wall of the cave. Such changes represented the major constraint for the occupation of the site - most of the time inaccessible to terrestrial mammals, it was used throughout by the eagle-owl, explaining the abundance of rabbit bones. Human occupation occurred during a few, short windows of availability, and is reflected in well-preserved living floors defined by hearths, artefact scatters, and the remains of hunted herbivores. The stone tool assemblages are Middle Paleolithic, which, in Europe, implies a Neandertal identity for their makers

  17. Coral Geochemical Proxy Records Of The East Asian Winter Monsoon And Hydrological Conditions In The Central Vietnam From 1978-2004 AD

    Science.gov (United States)

    Chang, C.; Shen, C.; Chen, Y.; Chiang, H.; Lam, D. D.; Ngai, N.

    2007-12-01

    Monthly-resolution geochemical proxies, including δ18O, δ13C, Sr/Ca, and Ba/Ca, in a living Porites coral head, collected from Son Tra Island, a near-shore island located at the north tip of Vung Da Nang Bay, central Vietnam (16°12'59.4", 108°1'57.1"), was used to quantitatively reconstruct records of sea surface temperature (SST), sea surface salinity (SSS), seasonality of rainfall, and regional terrestrial input during a period of 1978-2004 AD. By comparing the 1/4-century geochemical data, five features are exhibited. (1) The coral Sr/Ca-inferred summer SSTs correspond well with the 1°x1° instrumental data to suggest that the regional SST record can be retrieved from this local coral head. (2) Interannual variation of coral winter SST data does not follow regional instrumental values. The harmonic phenomenon between coral inferred winter SST dynamic and the surface pressure difference, between the southern South China Sea (SCS) (0-10°N, 105-115°E) and the northern SCS (22.5-32.5°N, 112-122°E), indicating that the cold local SST induced by East Asian winter monsoon was addressed in the Son Tra coral. (3) 1‰ seasonal anomaly of δ18O residual (Δδ18O) suggests a 2-4-psu seasonal salinity change between dry and wet seasons. (4) The synchronous intra-annual changes of δ18O and Ba/Ca data suggest that the rainy season is from late summer to winter, which is consistent with the meteorological record. (5) The high Ba/Ca background level of 10 μmol/mol in 1992-2004, 2-3 times larger than the averaged value of 4 μmol/mol in 1978-1992, indicates an enhanced terrestrial sediment discharge into the bay over the past 10 years. Ba records probably reflect an impact of human activity on hydrological change since the Vietnam War.

  18. Methylation and cyclisation of branched glycerol dialkyl glycerol tetraethers as temperature and pH proxies

    Science.gov (United States)

    Blaga, C. I.; Reichart, G.-J.; Schouten, S.; Lotter, A.; Sinninghe Damste, J. S.

    2009-04-01

    Branched glycerol dialkyl glycerol tetraethers (GDGTs) containing 0 to 2 cyclopentyl moieties were initially detected in peat deposits [1]. Through the analysis of a global set of soils samples Weijers et al. [2] showed that these GDGTs, probably of bacterial origin, are produced in situ in these soils. Rivers and direct run-off transport these compounds, together with other soil organic matter, to marine [3] and lake sediments [4, 5]. Recently, Weijers et al. [6] defined two indices that are based on branched GDGTs that are distinctively influenced by two environmental factors. The cyclisation ratio of the branched tetraethers (CBT) is related to soil pH and the methylation index of branched tetraethers (MBT) is related to temperature and soil pH. Lake sediments are often used for reconstructing past climatic changes. The presence of branched GDGTs in lake sediments potentially allows reconstruction of temperature and pH of the lake drainage area. We performed organic geochemical analyses on a series of surface sediments from 82 lakes characterised by variable amounts of soil organic matter and from different geographical locations to establish the application of the MBT/CBT as a continental palaeothermometer. Results show that in all of the 82 lakes substantial amounts of branched GDGTs are present (0.1-28% of total GDGTs). Besides the branched GDGTs crenarchaeol was also found in appreciable amounts (on average 23% of the total GDGTs). In the lakes from the northern hemisphere in fact the dominant GDGT is crenarchaeol (38% of total GDGTs) followed by the pentamethylated branched GDGT. In the southern hemisphere on the other hand we observe the hexamethylated branched GDGT as the dominant GDGT and crenarchaeol is here ten times less abundant then in the north (on average 3% of total GDGTs only). The CBT, as defined by Weijers et al. [6], for the entire data set ranges from values close to 0 (0.14 for Lake Ohrid) to 1.7 (Lake Nyos). The MBT ratio, also as defined

  19. Calibration, validation and application of foraminiferal carbonate based proxies. Reconstructing temperature, salinity and sea water Mg/Ca

    NARCIS (Netherlands)

    Wit, J.C.

    2012-01-01

    The chemistry of the calcite test of foraminifera is often relating to the environmental conditions under which they lived. These so-called proxy-relations are regularly used as a tool to reconstruct past climates. Accuracy of these proxies is, however, often limited due to uncertainties or absence

  20. Coherent millennial-scale patterns in U37k‧ and TEX86H temperature records during the penultimate interglacial-to-glacial cycle in the western Mediterranean

    Science.gov (United States)

    Huguet, Carme; Martrat, Belen; Grimalt, Joan O.; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2011-06-01

    The TEX86H temperature proxy is a relatively new proxy based on crenarchaeotal lipids and has rarely been applied together with other temperature proxies. In this study, we applied the TEX86H on a sediment core from the Alboran Sea (western Mediterranean, core ODP-977A) covering the penultimate climate cycle, that is, from 244 to 130 ka, and compared this with previously published sea surface temperatures derived from the U37k' of alkenones of haptophyta and Mg/Ca records of planktonic foraminifera. The TEX86H temperature record shows remarkably similar stadial-interstadial patterns and abrupt temperature changes to those observed with the U37k' palaeothermometer. Absolute TEX86H temperature estimates are generally higher than those of U37k', though this difference (crenarchaeota and haptophyta experienced similar temperature variations. During occasional events (<5% of the analyzed time span), however, the TEX86H exhibits considerably higher absolute temperature estimates than the U37k'. Comparison with Mg/Ca records of planktonic foraminifera as well as other Mediterranean TEX86 and U37k' records suggests that part of this divergence may be attributed to seasonal differences, that is, with TEX86H reflecting mainly the warm summer season while U37k' would show annual mean. Biases in the global calibration of both proxies or specific biases in the Mediterranean are an alternative, though less likely, explanation. Despite differences between absolute TEX86H and U37k' temperatures, the correlation between the two proxies (r2 = 0.59, 95% significance) provides support for the occurrence of abrupt temperature variations in the western Mediterranean during the penultimate interglacial-to-glacial cycle.

  1. Development of the Wintertime Sr/Ca-SST Record from Red Sea Corals as a Proxy for the North Atlantic Oscillation

    Science.gov (United States)

    Bernstein, W. N.; Hughen, K. A.

    2009-12-01

    The North Atlantic Oscillation (NAO) is one of the most pronounced and influential patterns in winter atmospheric circulation variability. This meridional redistribution of atmospheric mass across the Atlantic Ocean produces large changes in the intensity, number and direction of storms generated within the basin, and the regional climate of surrounding continents. The NAO exerts a significant impact on society, through influences on agriculture, fisheries, water management, energy generation and coastal development. NAO effects on climate extend from eastern North America across Europe to the eastern Mediterranean and Middle East. Changes in NAO behavior during the late 20th century have been linked to global warming; yet despite its importance, the causes and long-term patterns of NAO variability in the past remain poorly understood. In order to better predict the influence of the NAO on climate in the future, it is critical to examine multi-century NAO variability. The Red Sea is an excellent location from which to generate long NAO records for two reasons. First, patterns of wintertime sea surface temperature (SST) and salinity (SSS) in the Red Sea are highly correlated with NAO variability (Visbeck et al. 2001; Hurrell et al. 2003). Second, the tropical/subtropical Red Sea region contains fast growing long-lived massive Porites spp. corals with annually banded skeletons. These corals are ideal for generating well-dated high-resolution paleoclimatic records that extend well beyond the instrumental period. Here we present a study of winter SST and NAO variability in the Red sea region based on coral Sr/Ca data. In 2008, we collected multiple drill cores ranging in length from 1 to 4.1 meters from Porites corals at six sites spanning a large SST gradient. Sr/Ca measurements from multiple corals will be regressed against 23 years of satellite SST data, expanding the SST range over which we calibrate. A sampling resolution of 0.5mm will yield greater than bi

  2. A multi-proxy record from the Quaternary Vienna Basin: Chronology, climate and environmental change at the Alpine-Carpathian transition during the last 250,000 years

    Science.gov (United States)

    Salcher, Bernhard; Lomax, Johanna; Frank, Christa; Preusser, Frank; Scholger, Robert; Ottner, Franz; Wagreich, Michael

    2016-04-01

    Dated multi-proxy records of terrestrial sequences in the Quaternary of the circum-Alpine realm are sparse. This is especially true for those exceeding the time span of the last glacial maximum as extensive glaciers eroded substantial parts of potential records. Outside formerly glaciated regions, preservation space is low in the absence of tectonic subsidence. Foreland terraces forming as a consequence of mountain range uplift may partly account for this gap but are typically dominated by coarse-grained fluvial sediments commonly reflecting only short pulses during cold stage periods. Here we analyze a terrestrial record in the Vienna Basin in order to derive regional climatic and environmental changes of the last c. 250 ka. The Vienna Basin forms as a classical pull-apart feature showing a length of almost 200 km and a width of c. 55 km. Quaternary subsidence is focused along the active Vienna Basin Transfer Fault leading to the formation of a series of narrow strike-slip (sub-) basins and grabens with the Mitterndorf sub-basin being the largest (c. 270 km²) and deepest (c.175 m). The southern part of the basin is confined by the alpine mountain front and fed by two alluvial fans highlighting up to several tens of meters thick coarse grained, massive sediments intercalated by up to few meters thick fine clastic sediments. We investigated the fan's sequence development through core and outcrop sampling applying luminescence dating, magnetostratigraphy, soil and lithofacies classification as well as malacological analysis. The latter comprise the determination and distribution of species and individuals as well as coenological analysis. Data suggest a distinct sequence development with coarse-grained massive sediments abundantly deposited during cold periods (MIS 2 and 6) and fine, overbank sediments and soils, dominantly forming during warmer, Interstadial or Interglacial periods (MIS 5 and 7). Overbanks and soils are generally rich in terrestrial mollusk

  3. Holocene moisture and East Asian summer monsoon evolution in the northeastern Tibetan Plateau recorded by Lake Qinghai and its environs: A review of conflicting proxies

    Science.gov (United States)

    Chen, Fahu; Wu, Duo; Chen, Jianhui; Zhou, Aifeng; Yu, Junqing; Shen, Ji; Wang, Sumin; Huang, Xiaozhong

    2016-12-01

    Climatic and environmental changes in the northeastern Tibetan Plateau are controlled by the Asian summer monsoon (ASM) and the westerlies, two key circulation components of the global climate system which directly affect a large human population and associated ecosystems in eastern Asia. During the past few decades, a series of Holocene palaeoclimatic records have been obtained from sediment cores from Lake Qinghai and from various other geological archives in the surrounding area of the northeastern Tibetan Plateau. However, because of uncertainties regarding the sediment chronologies and the climatic significance of the proxies used, the nature of Holocene climatic changes in the region remains unclear and even controversial. Here we review all major classes of the published data from drilled cores from Lake Qinghai, as well as other evidence from lakes and aeolian deposits from surrounding areas, in order to reconstruct changes in moisture patterns and possible summer monsoon evolution in the area during the Holocene. Combining the results of moisture and precipitation proxies such as vegetation history, pollen-based precipitation reconstruction, aeolian activity, lake water depth/lake level changes, salinity and sediment redness, we conclude that moisture and precipitation began to increase in the early Holocene, reached their maximum during the middle Holocene, and decreased during the late Holocene - similar to the pattern of the East Asian summer monsoon (EASM) in northern China. It is clear that the region experienced a relatively dry climate and weak EASM during the early Holocene, as indicated by relatively low tree pollen percentages and fluctuating pollen concentrations; generally low lake levels of Lake Qinghai and the adjacent Lake Hurleg and Lake Toson in the Qaidam Basin; and widely distributed aeolian sand deposition in the Lake Qinghai Basin and the nearby Gonghe Basin to the south, and in the eastern Qaidam Basin to the west. We argue that the

  4. Middle to Late Pleistocene multi-proxy record of environmental response to climate change from the Vienna Basin, Central Europe (Austria)

    Science.gov (United States)

    Salcher, Bernhard C.; Frank-Fellner, Christa; Lomax, Johanna; Preusser, Frank; Ottner, Franz; Scholger, Robert; Wagreich, Michael

    2017-10-01

    Tectonic basins can represent valuable archives of the environmental history. Presented here are the stratigraphy and multi-proxy analyses of two adjacent alluvial fans in the Quaternary active parts of the Vienna Basin, situated at the interface of the Atlantic, European continental and Mediterranean climate. Deposits comprise a sequence of coarse-grained fluvial deposits intercalated by laterally extensive horizons of pedogenically altered fine sediments. To establish palaeoenvironmental reconstructions, fine-grained sequences from a drill core and outcrop data were analysed according to its malacofauna, palaeopedology, susceptibility and sedimentology. The chronological framework is provided by 38 luminescence ages and supported by geomagnetic polarity investigations. Distinct warm periods each associated with a geomagnetic excursion, are recorded in three pedocomplexes formed during the Last Interglacial and two earlier interglacial periods, indicted to correlate with Marine Isotope Stage (MIS) 9 and MIS 11, respectively. Environmental conditions during the early last glacial period (MIS 5, c. 100-70 ka) are reconstructed from mollusc-shell rich overbank fines deposited along a former channel belt, covered by massive sheetflood deposits during MIS 2. Analysed warm phases suggest strong variations in humidity, ranging from steppe to forest dominated environments. The study presents one of the few numerically dated Middle Pleistocene multi-proxy records and one of the most comprehensive malacological datasets covering the early phases of last glacial period of continental Europe.

  5. Is the Atlantic surface temperature a good proxy for forecasting the recruitment of European eel in the Guadalquivir estuary?

    Science.gov (United States)

    Gutiérrez-Estrada, Juan Carlos; Pulido-Calvo, Inmaculada

    2015-01-01

    This study analysed the possibility of using the sea surface temperature (SST) of the Atlantic Ocean to predict the recruitment of European eels in one of the most important estuaries of the south of Europe. For this purpose, two different time series concerning glass eel in the Guadalquivir estuary (the first obtained from a set of fishery-independent experimental samplings in this estuary and the second from an unofficial database on commercial catches provided by one of the main local marketer-buyers) were standardised to obtain a single time series on a monthly scale. This series was correlated with a total of 368 SST time series for 368 sectors of 1.95° × 1.95° of the Atlantic Ocean covering the possible migration routes of adult eels and leptocephalous larvae. The significant sectors were clustered and selected as inputs for artificial neural network models (ANNs) with the objective of obtaining a model to forecast glass eel recruitment. Globally, the best result was given by an ANN with only 12 clusters as input variables and 35 neurons in the hidden layer. For this configuration, the explained variance in the test phase was slightly higher than 79%. These results were significantly better than those obtained with classical methods. The strong correlation between predicted and observed glass eel abundance suggests that: (a) there is a marked non-linear relationship between SST and glass eel recruitment in the Guadalquivir estuary; (b) SST is a good proxy for predicting glass eel recruitment and; (c) one of the main factors responsible for the changes in abundance of this species is changes in the ocean conditions.

  6. Exploring Type-and-Identity-Based Proxy Re-Encryption Scheme to Securely Manage Personal Health Records

    NARCIS (Netherlands)

    Ibraimi, L.; Gangopadhyay, Aryya; Tang, Qiang; Hartel, Pieter H.; Jonker, Willem

    2010-01-01

    Commercial Web-based Personal-Health Record (PHR) systems can help patients to share their personal health records (PHRs) anytime from anywhere. PHRs are very sensitive data and an inappropriate disclosure may cause serious problems to an individual. Therefore commercial Web-based PHR systems have

  7. Differential proxy responses to late Allerød and early Younger Dryas climatic change recorded in varved sediments of the Trzechowskie palaeolake in Northern Poland

    Science.gov (United States)

    Słowiński, Michał; Zawiska, Izabela; Ott, Florian; Noryśkiewicz, Agnieszka M.; Plessen, Birgit; Apolinarska, Karina; Rzodkiewicz, Monika; Michczyńska, Danuta J.; Wulf, Sabine; Skubała, Piotr; Kordowski, Jarosław; Błaszkiewicz, Mirosław; Brauer, Achim

    2017-02-01

    High-resolution biological proxies (pollen, macrofossils, Cladocera and diatoms), geochemical data (μ-XRF element scans, TOC, C/N ratios, δ18Ocarb and δ13Corg values) and a robust chronology based on varve counting, AMS 14C dating and tephrochronology were applied to reconstruct lake system responses to rapid climatic and environmental changes of the Trzechowskie palaeolake (TRZ; Northern Poland) during the late Allerød - Younger Dryas (YD) transition. Palaeoecological and geochemical data at 5-15 years temporal resolution allowed tracing the dynamics of short-term shifts of the ecosystem triggered by abrupt climate change. The robust age control together with the high-resolution sampling allowed the detection of leads and lags between different proxies to the climate shift at the Allerød-Younger Dryas transition. Our results indicate (1) a water level decrease and an increase in wind activities during the late Allerød and the Allerød-YD transition, which caused intensified erosion in the catchment, (2) a two-decades delayed vegetation response in comparison to the lake depositional system. Comparison with the Lake Meerfelder Maar record revealed slightly different vegetation responses of the Trzechowskie palaeolake at the YD onset.

  8. New directions in hydro-climatic histories: observational data recovery, proxy records and the atmospheric circulation reconstructions over the earth (ACRE) initiative in Southeast Asia

    Science.gov (United States)

    Williamson, Fiona; Allan, Rob; Switzer, Adam D.; Chan, Johnny C. L.; Wasson, Robert James; D'Arrigo, Rosanne; Gartner, Richard

    2015-12-01

    The value of historic observational weather data for reconstructing long-term climate patterns and the detailed analysis of extreme weather events has long been recognized (Le Roy Ladurie, 1972; Lamb, 1977). In some regions however, observational data has not been kept regularly over time, or its preservation and archiving has not been considered a priority by governmental agencies. This has been a particular problem in Southeast Asia where there has been no systematic country-by-country method of keeping or preserving such data, the keeping of data only reaches back a few decades, or where instability has threatened the survival of historic records. As a result, past observational data are fragmentary, scattered, or even absent altogether. The further we go back in time, the more obvious the gaps. Observational data can be complimented however by historical documentary or proxy records of extreme events such as floods, droughts and other climatic anomalies. This review article highlights recent initiatives in sourcing, recovering, and preserving historical weather data and the potential for integrating the same with proxy (and other) records. In so doing, it focuses on regional initiatives for data research and recovery - particularly the work of the international Atmospheric Circulation Reconstructions over the Earth's (ACRE) Southeast Asian regional arm (ACRE SEA) - and the latter's role in bringing together disparate, but interrelated, projects working within this region. The overarching goal of the ACRE SEA initiative is to connect regional efforts and to build capacity within Southeast Asian institutions, agencies and National Meteorological and Hydrological Services (NMHS) to improve and extend historical instrumental, documentary and proxy databases of Southeast Asian hydroclimate, in order to contribute to the generation of high-quality, high-resolution historical hydroclimatic reconstructions (reanalyses) and, to build linkages with humanities researchers

  9. Global increase in record-breaking monthly-mean temperatures

    NARCIS (Netherlands)

    Coumou, Dim; Robinson, Alexander; Rahmstorf, Stefan

    The last decade has produced record-breaking heat waves in many parts of the world. At the same time, it was globally the warmest since sufficient measurements started in the 19th century. Here we show that, worldwide, the number of local record-breaking monthly temperature extremes is now on

  10. Evidence of a warm early instrumental period found in temperature related water isotope records from high elevation Alpine ice cores

    Science.gov (United States)

    Bohleber, Pascal; Schöner, Wolfgang; Wagenbach, Dietmar

    2015-04-01

    The variability of water isotopes (delta-O18 or delta-D) preserved in Alpine glacier ice may provide mid-latitude temperature proxy records supplementing respective information from other archives. In order to archive long term records (i.e. exceeding 100 years) the limited glacier depth at suitable Alpine drill sites requires a relatively low net accumulation rate. In this respect, the cold glacier saddle Colle Gnifetti (CG) is the unique drilling site in the European Alps offering ice core records substantially exceeding the instrumental period. However, the unique low net accumulation at CG is characterised by strong spatio-temporal variability causing depositional noise that strongly challenges the interpretation of the ice core isotope records in terms of net temperature change. Here we present our findings from comparing stable water isotope records of the CG multi core array to a site-specific temperature time series. The latter is synthesized from high elevation stations of the instrumental HISTALP network considering among others the temperature shift from the accumulation bias towards growing seasons. Within the last century dedicated time series analysis reveals a common signal in the (supra-) decadal components of the instrumental temperature and isotope records. Extending the comparison over the entire 250 years instrumental period, systematic discrepancies are found within the early instrumental period (EIP). The delta-O18 record shows an overall decreasing trend from 1760 to 1890 AD, which is not reflected in the temperature record. However, using high Alpine summer temperature lacking the latest EIP adjustment, the long-term trends between isotope and instrumental data are in better agreement. The overall mean of the isotope based temperature in the EIP indicates substantially warmer levels than the EIP-corrected instrumental temperature. It differs, however, not significantly with respect to the non-EIP-corrected temperature mean. Although the main

  11. Mapping Ancient Forests: Bayesian Inference for Spatio-temporal Trends in Forest Composition Using the Fossil Pollen Proxy Record

    OpenAIRE

    Paciorek, Christopher J.; McLachlan, Jason S.

    2009-01-01

    Ecologists use the relative abundance of fossil pollen in sediments to estimate how tree species abundances change over space and time. To predict historical forest composition and quantify the available information, we build a Bayesian hierarchical model of forest composition in central New England, USA, based on pollen in a network of ponds. The critical relationships between abundances of taxa in the pollen record and abundances as actual vegetation are estimated for the modern and colonia...

  12. Long-term Hydroclimate and Pacific Salmon Population Linkages Across a Headwater-to-Coast Continuum in Northern British Columbia, Canada: A Perspective From Multiple Tree-Ring Proxy Records

    Science.gov (United States)

    Welsh, C.; Smith, D. J.; Edwards, T.; Prowse, T.

    2016-12-01

    Ongoing climate change is expected to have lasting impacts on the runoff behaviour of rivers in northern British Columbia, Canada. Of particular concern is the loss of mountain snowpack and greater rainfall totals altering hydrograph characteristics. Sustained deviations in seasonal streamflow will pose significant challenges for effective watershed management. These ongoing changes highlight the importance of improving our understanding of the long-term biophysical linkages between the storage and release of water and downstream freshwater ecosystems. Such integrated research is particularly relevant to fisheries management as fluctuations in populations of Pacific salmon represent a complex and management-relevant biophysical issue in northern Canada. Unfortunately, hydroclimate and salmon productivity records in this region are sparse and of short duration, constraining our understanding of the impact of climate-induced hydrologic changes and biological responses to the last century. Proxy records derived from tree-rings provide annually or seasonally resolved data and have played a prominent role in attempts to establish how hydroclimate has varied in the past. The objective of my doctoral research is to reconstruct the prehistoric hydroclimate and salmon population trends in the Skeena, Nass and Stikine Watersheds using multiple tree-ring proxies to investigate the long-term biophysical linkages extending across a headwater-to-coast continuum in northern British Columbia, Canada. Ring-width, wood density and stable isotope chronologies using a number of mid-to high-elevation tree species will be constructed across each basin and sub-basin area for the purposes of reconstrucing the predominent temperature and precipiation signature that influence streamflow. Preliminary tree-ring δ18O and δ13C-isotope results indicate a strong negative association with mean monthly relative humidity values, suggesting a physiological control by moisture loss. The results of

  13. Coral record of southeast Indian Ocean marine heatwaves with intensified Western Pacific temperature gradient

    Science.gov (United States)

    Zinke, J.; Hoell, A.; Lough, J. M.; Feng, M.; Kuret, A. J.; Clarke, H.; Ricca, V.; Rankenburg, K.; McCulloch, M. T.

    2015-10-01

    Increasing intensity of marine heatwaves has caused widespread mass coral bleaching events, threatening the integrity and functional diversity of coral reefs. Here we demonstrate the role of inter-ocean coupling in amplifying thermal stress on reefs in the poorly studied southeast Indian Ocean (SEIO), through a robust 215-year (1795-2010) geochemical coral proxy sea surface temperature (SST) record. We show that marine heatwaves affecting the SEIO are linked to the behaviour of the Western Pacific Warm Pool on decadal to centennial timescales, and are most pronounced when an anomalously strong zonal SST gradient between the western and central Pacific co-occurs with strong La Niña's. This SST gradient forces large-scale changes in heat flux that exacerbate SEIO heatwaves. Better understanding of the zonal SST gradient in the Western Pacific is expected to improve projections of the frequency of extreme SEIO heatwaves and their ecological impacts on the important coral reef ecosystems off Western Australia.

  14. To what extent do water isotope records from low accumulation Alpine ice cores reproduce instrumental temperature series?

    Directory of Open Access Journals (Sweden)

    Pascal Bohleber

    2013-04-01

    Full Text Available Among Alpine ice core drilling sites, the Colle Gnifetti glacier saddle situated in the Monte Rosa summit range is the only one whose net snow accumulation rate is low enough to offer climate records back to some 1000 yr. It is demonstrated that the strong snow erosion at this site particularly hampers the interpretation of stable water isotope records δ18O, δD in terms of atmospheric temperature changes. We evaluate the δ18O records from four Colle Gnifetti cores for their common variability to extract a composite isotope record that may be compared with the instrumental temperature evidence. Time series analyses over the last 120 yr reveal that the common δ18O signal is mainly reflected in the low frequency variability, starting at the decadal scale. Comparing the correspondingly smoothed composite record to the high-elevation temperature time series (specifically adjusted to the seasonality of the net snow accumulation reveals the following findings: On the decadal scale, the isotope variability correlates with the temperature record at around R=0.65 but is interrupted by three, ca. 10-yr long mismatch periods. The multidecadal isotope signal closely reflects the strong overall 20th century temperature increase, thereby showing an up to three-fold higher isotope temperature sensitivity than commonly assumed. Over the entire instrumental period back to 1760, five more such mismatch periods are embedded in the generally coherent pattern of the δ18O and instrumental temperature records (including the strong overestimate of the temperature around 1850 by the isotope temperature proxy. For the early instrumental period (1890–1760 characterized by a comparably weak long-term temperature trend, the isotope signal generally suggests warmer conditions of about 0.4°C compared to instrumental data.

  15. Ecosystem Disturbances in Central European Spruce Forests: a Multi-proxy Integration of Dendroecology and Sedimentary Records

    Science.gov (United States)

    Clear, J.; Chiverrell, R. C.; Kunes, P.; Boyle, J.; Kuosmanen, N.; Carter, V.

    2016-12-01

    The montane Norway spruce (Picea abies) dominated forests of Central Europe are a niche environment; situated outside their natural boreal distribution they are vulnerable to both short term disturbances (e.g. floods, avalanches, fire, windstorm and pathogens) and longer-term environmental change (e.g. climate induced stress, snow regimes). Holocene sediment records from lakes in the High Tatra (Slovakia) and Bohemian (Czech) Mountains show repeated disturbances of the pristine Picea abies-dominated forests as sharp well defined minerogenic in-wash horizons that punctuate the accumulation of organic gyttja. These event horizons span a process continuum from lakes with restricted catchments and limited inflow (e.g. Prazilske Lake, Czech) to more catchment-process dominated lakes with large catchments (e.g. Popradske Lake, Slovakia). The events include complex responses to a global climatic downturn at 8.2ka, other cooler episodes 3.5, 1.6 and 0.5 ka, and to recent discrete wind-storms and pathogen outbreaks. We develop a typology for disturbance events using sediment geochemistry, particle size, mineral magnetism, charcoal and palaeoecology to assess likely drivers of disturbance. For the recent past integrating data from dendroecology and sediments is used to calibrate our longer-term perspective on forest dynamics. Tree-ring series from plots or forest stands are used alongside lake and forest hollow sediments to explore the local, regional and biogeographical scale of forest disturbances. Dendroecological data showing tree-ring gap recruitment and post-suppression growth release highlight frequent disturbance events focused on tree or forest stand spatial scales, but are patchy in terms of their reoccurrence. However they highlight levels of disturbance in the late 19th Century and parallel lake and forest hollow sediments record variable pollen influx (beetle host / non-host ratios) and stratigraphies that include mineral in-wash events. The identified recent

  16. Summer temperatures in the Canadian Rockies during the last millennium: a revised record

    Energy Technology Data Exchange (ETDEWEB)

    Luckman, B.H. [University of Western Ontario, Department of Geography, London, Ontario (Canada); Wilson, R.J.S. [Edinburgh University, School of GeoSciences, Grant Institute, Edinburgh (United Kingdom)

    2005-02-01

    We present a significant update to a millennial summer temperature reconstruction (1073-1983) that was originally published in 1997. Utilising new tree-ring data (predominantly Picea engelmannii), the reconstruction is not only better replicated, but has been extended (950-1994) and is now more regionally representative. Calibration and verification statistics were improved, with the new model explaining 53% of May-August maximum temperature variation compared to the original (39% of April-August mean temperatures). The maximum latewood density data, which are weighted more strongly in the regression model than ringwidth, were processed using regional curve standardisation to capture potential centennial to millennial scale variability. The reconstruction shows warm intervals, comparable to twentieth century values, for the first half of the eleventh century, the late 1300s and early 1400s. The bulk of the record, however, is below the 1901-1980 normals, with prolonged cool periods from 1200 to 1350 and from 1450 to the late 19th century. The most extreme cool period is observed to be in the 1690s. These reconstructed cool periods compare well with known regional records of glacier advances between 1150 and the 1300s, possibly in the early 1500s, early 1700s and 1800s. Evidence is also presented of the influence of solar activity and volcanic events on summer temperature in the Canadian Rockies over the last 1,000 years. Although this reconstruction is regional in scope, it compares well at multi-decadal to centennial scales with Northern Hemisphere temperature proxies and at millennial scales with reconstructions that were also processed to capture longer timescale variability. This coherence suggests that this series is globally important for the assessment of natural temperature variability over the last 1,000 years. (orig.)

  17. High Resolution, Multi-Proxy Records of Holocene Biomass Burning, Environmental Change, and Human Occupation in the Southern Maya Lowlands

    Science.gov (United States)

    Anderson, L.; Wahl, D.

    2011-12-01

    Understanding the relationship between the prehistoric Maya and their environment continues to be a primary research focus, particularly with respect to discerning the role of humans versus climate in driving environmental change. Fire was fundamental to prehistoric Maya architectural and agricultural land use practices. Burning was used to open forest for cultivation as well as for the construction of site centers and settlements. The production of lime plaster, and important building material, was dependent on significant amounts of green wood for kiln fuel. Large populations employing land use strategies dependent on burning would have put tremendous demands on forest resources. Despite the significance of fire in Maya pre-history, there has been no focused effort to produce records of biomass burning and its impacts. Here we present preliminary high-resolution fossil charcoal data that span the Holocene from a network of lacustrine and paludal sites across Peten, Guatemala. Charcoal influx data from the early to mid Holocene, prior to the arrival of sedentary agriculturalists, provides a baseline to infer natural fire regimes under specific climatic conditions, increasing our understanding of tropical fire ecology. Charcoal deposition that co-varies with evidence of agriculture and human activity can be attributed to anthropogenic burning. Results are synthesized with existing data (pollen, δ18O and δ13C, magnetic susceptibility, and physical properties) in an effort to understand the processes driving the location, timing, and extent of fires across the region. Placed in the context of changes in vegetation, sedimentation regime, and hydrology, these data provide new insight into topical fire ecology before the period of human occupation, as well as the dynamic relationship between the prehistoric Maya and their environment.

  18. Mapping Ancient Forests: Bayesian Inference for Spatio-temporal Trends in Forest Composition Using the Fossil Pollen Proxy Record.

    Science.gov (United States)

    Paciorek, Christopher J; McLachlan, Jason S

    2009-06-01

    Ecologists use the relative abundance of fossil pollen in sediments to estimate how tree species abundances change over space and time. To predict historical forest composition and quantify the available information, we build a Bayesian hierarchical model of forest composition in central New England, USA, based on pollen in a network of ponds. The critical relationships between abundances of taxa in the pollen record and abundances as actual vegetation are estimated for the modern and colonial periods, for which both pollen and direct vegetation data are available, based on a latent multivariate spatial process representing forest composition. For time periods in the past with only pollen data, we use the estimated model parameters to constrain predictions about the latent spatio-temporal process conditional on the pollen data. We develop an innovative graphical assessment of feature significance to help to infer which spatial patterns are reliably estimated. The model allows us to estimate the spatial distribution and relative abundances of tree species over the last 2500 years, with an assessment of uncertainty, and to draw inference about how these patterns have changed over time. Cross-validation suggests that our feature significance approach can reliably indicate certain large-scale spatial features for many taxa, but that features on scales smaller than 50 km are difficult to distinguish, as are large-scale features for some taxa. We also use the model to quantitatively investigate ecological hypotheses, including covariate effects on taxa abundances and questions about pollen dispersal characteristics. The critical advantages of our modeling approach over current ecological analyses are the explicit spatio-temporal representation, quantification of abundance on the scale of trees rather than pollen, and uncertainty characterization.

  19. Speleothem stable isotope records for east-central Europe: resampling sedimentary proxy records to obtain evenly spaced time series with spectral guidance

    Science.gov (United States)

    Gábor Hatvani, István; Kern, Zoltán; Leél-Őssy, Szabolcs; Demény, Attila

    2018-01-01

    Uneven spacing is a common feature of sedimentary paleoclimate records, in many cases causing difficulties in the application of classical statistical and time series methods. Although special statistical tools do exist to assess unevenly spaced data directly, the transformation of such data into a temporally equidistant time series which may then be examined using commonly employed statistical tools remains, however, an unachieved goal. The present paper, therefore, introduces an approach to obtain evenly spaced time series (using cubic spline fitting) from unevenly spaced speleothem records with the application of a spectral guidance to avoid the spectral bias caused by interpolation and retain the original spectral characteristics of the data. The methodology was applied to stable carbon and oxygen isotope records derived from two stalagmites from the Baradla Cave (NE Hungary) dating back to the late 18th century. To show the benefit of the equally spaced records to climate studies, their coherence with climate parameters is explored using wavelet transform coherence and discussed. The obtained equally spaced time series are available at https://doi.org/10.1594/PANGAEA.875917" target="_blank">https://doi.org/10.1594/PANGAEA.875917.

  20. A multi-proxy record of hydroclimate, vegetation, fire, and post-settlement impacts for a subalpine plateau, Central Rocky Mountains U.S.A

    Science.gov (United States)

    Anderson, Lesleigh; Brunelle, Andrea; Thompson, Robert S.

    2015-01-01

    Apparent changes in vegetation distribution, fire, and other disturbance regimes throughout western North America have prompted investigations of the relative importance of human activities and climate change as potential causal mechanisms. Assessing the effects of Euro-American settlement is difficult because climate changes occur on multi-decadal to centennial time scales and require longer time perspectives than historic observations can provide. Here, we report vegetation and environmental changes over the past ~13,000 years as recorded in a sediment record from Bison Lake, a subalpine lake on a high plateau in northwestern Colorado. Results are based on multiple independent proxies, which include pollen, charcoal, and elemental geochemistry, and are compared with previously reported interpretations of hydroclimatic changes from oxygen isotope ratios. The pollen data indicate a slowly changing vegetation sequence from sagebrush steppe during the late glacial to coniferous forest through the late Holocene. The most dramatic vegetation changes of the Holocene occurred during the ‘Medieval Climate Anomaly’ (MCA) and ‘Little Ice Age’ (LIA) with rapid replacement of conifer forest by grassland followed by an equally rapid return to conifer forest. Late Holocene vegetation responses are mirrored by changes in fire, lake biological productivity, and watershed erosion. These combined records indicate that subsequent disturbance related to Euro-American settlement, although perhaps significant, had acted upon a landscape that was already responding to MCA-LIA hydroclimatic change. Results document both rapid and long-term subalpine grassland ecosystem dynamics driven by agents of change that can be anticipated in the future and simulated by ecosystem models.

  1. Constraining past seawater δ18O and temperature records developed from foraminiferal geochemistry

    Science.gov (United States)

    Quinn, T. M.; Thirumalai, K.; Marino, G.

    2016-12-01

    Paired measurements of magnesium-to-calcium ratios (Mg/Ca) and the stable oxygen isotopic composition (δ18O) in foraminifera have significantly advanced our knowledge of the climate system by providing information on past temperature and seawater δ18O (δ18Osw, a proxy for salinity and ice volume). However, multiple sources of uncertainty exist in transferring these downcore geochemical data into quantitative paleoclimate reconstructions. Here, we develop a computational toolkit entitled Paleo-Seawater Uncertainty Solver (PSU Solver) that performs bootstrap Monte Carlo simulations to constrain these various sources of uncertainty. PSU Solver calculates temperature and δ18Osw, and their respective confidence intervals using an iterative approach with user-defined errors, calibrations, and sea-level curves. Our probabilistic approach yields reduced uncertainty constraints compared to theoretical considerations and commonly used propagation exercises. We demonstrate the applicability of PSU Solver for published records covering three timescales: the late Holocene, the last deglaciation, and the last glacial period. We show that the influence of salinity on Mg/Ca can considerably alter the structure and amplitude of change in the resulting reconstruction and can impact the interpretation of paleoceanographic time series. We also highlight the sensitivity of the records to various inputs of sea-level curves, transfer functions, and uncertainty constraints. PSU Solver offers an expeditious yet rigorous approach to test the robustness of past climate variability inferred from paired Mg/Ca-δ18O measurements.

  2. Did European temperatures in 1540 exceed present-day records?

    Science.gov (United States)

    Orth, Rene; Vogel, Martha M.; Luterbacher, Jürg; Pfister, Christian; Seneviratne, Sonia I.

    2017-04-01

    There is strong evidence that the year 1540 was exceptionally dry and warm in Central Europe. Here we infer 1540 summer temperatures from the number of dry days (NDDs) in spring (March-May) and summer (June-August) in 1540 derived from historical documentary evidence published elsewhere, and compare our estimates with present-day temperatures. We translate the NDD values into temperature distributions using a linear relationship between modeled temperature and NDD from a 3000 year pre-industrial control simulation with the Community Earth System Model (CESM). Our results show medium confidence that summer mean temperatures (T JJA) and maximum temperatures (TXx) in Central Europe in 1540 were warmer than the respective present-day mean summer temperatures (assessed between 1966-2015). The model-based reconstruction suggests further that with a probability of 40%-70%, the highest daily temperatures in 1540 were even warmer than in 2003, while there is at most a 20% probability that the 1540 mean summer temperature was warmer than that of 2003 in Central Europe. As with other state-of-the-art analyses, the uncertainty of the reconstructed 1540 summer weather in this study is considerable, for instance as extrapolation is required because 1540-like events are not captured by the employed Earth system model (ESM), and neither by other ESMs. However, in addition to paleoclimatological approaches we introduce here an independent methodology to estimate 1540 temperatures, and contribute consequently to a reduced overall uncertainty in the analysis of this event. The characterization of such events and the related climate system functioning is particularly relevant in the context of global warming and the corresponding increase of extreme heat wave magnitude and occurrence frequency. Orth, R., M.M. Vogel, J. Luterbacher, C. Pfister, and S.I. Seneviratne, (2016): Did European temperatures in 1540 exceed present-day records? Env. Res. Lett., 11, 114021, doi: 10.1088/1748-9326/11/11/114021

  3. The preglacial sediment record of Lake Ladoga, NW Russia - first results from a multi-proxy study on a 23 m sediment record

    Science.gov (United States)

    Gromig, R.; Melles, M.; Wagner, B.; Krastel, S.; Andreev, A.; Fedorov, G.; Just, J.; Wennrich, V.; Savelieva, L.; Subetto, D.; Shumilovskikh, L.

    2016-12-01

    The joint German-Russian project 'PLOT - Paleolimnological Transect' aims to recover lake sediment sequences along a more than 6000 km long longitudinal transect across the Eurasian Arctic in order to study the Late Quaternary climatic and environmental history. The eastern end of the PLOT transect is formed by the well-studied record from Lake El'gygytgyn (NE Siberia). Lake Ladoga (N 60°50' E 31°30') is Europe's largest lake, both by size and volume and forms the westernmost end of the transect. Whereas modern sedimentation as well as the Holocene and Late Glacial history of Lake Ladoga have intensely been studied, the preglacial history of the lake is poorly studied to date by sediment cores drilled in the 1930's. A seismic survey of Lake Ladoga in summer 2013 revealed unconformities in the western lake basin, which may separate preglacial sediments in isolated depressions from Late Glacial and Holocene sediment successions above. A 23 m long sediment core (Co1309) was retrieved from one of these depressions. Core Co1309 was investigated by XRF-scanning, magnetic susceptibility measurements, as well as pollen, grain-size, and bio-geochemical analyses. An age-depth model combining radiocarbon, OSL, and paleomagnetic dates is in progress. Both, the pollen results and the OSL ages from the base of the record indicate a deposition during MIS 5e (Eemian). The well sorted reddish sands from this interval contain dinoflagellates suggesting at least brackish conditions, likely due to the existence of a gateway connecting a precursor of the Baltic Sea with the White Sea via Lake Ladoga. The Late Glacial sequence consists of greyish varved clays of decreasing thickness upwards with sporadically intercalated sand layers. The Holocene sequence is composed of brownish diatomaceous silty clay with minor proportions of sand.

  4. Mass accumulation rate of detrital materials in Lake Suigetsu as a potential proxy for heavy precipitation: a comparison of the observational precipitation and sedimentary record

    Science.gov (United States)

    Suzuki, Yoshiaki; Tada, Ryuji; Yamada, Kazuyoshi; Irino, Tomohisa; Nagashima, Kana; Nakagawa, Takeshi; Omori, Takayuki

    2016-02-01

    In the densely populated region of East Asia, it is important to know the mechanism, scale, and frequency of heavy precipitation brought about during the monsoons and typhoons. However, observational data, which cover only several decades, are insufficient to examine the long-term trend of extreme precipitation and its background mechanism. In humid areas, the transport flux of a suspended detrital material through a river system is known to have an empirical power relationship with precipitation. Thus, the sedimentation flux of a fine detrital material could potentially be used as a proxy for reconstructing past heavy precipitation events. To test the idea that the sedimentation flux of detrital materials records past heavy precipitation events (e.g., typhoons), we focused on the detrital flux estimated from the annually laminated sediment of Lake Suigetsu, central Japan, which is capable of accurately correlating the age of detrital flux with the precipitation record. We first established a precise age model (error within ±1 year in average) beginning in 1920 A.D. on the basis of varve counting fine-tuned by correlation between event layers with historical floods. The flux of the detrital material (g/cm2/year) was estimated on the basis of Al2O3 content (wt%), dry bulk density (g/cm3), and sedimentation rate (cm/year) calculated from the age model. The detrital flux of background sedimentation showed a weak positive correlation with annual and monthly (June and September) precipitation excluding heavy precipitation that exceeded 100 mm/day. Furthermore, the thickness of instantaneous event layers, which corresponds to several maxima of detrital flux and is correlated with floods that occurred mainly during typhoons, showed a positive relationship with the total amount of precipitation that caused a flood event. This result suggests that the detrital flux maxima (deposition of event layers) record past extreme precipitation events that were likely associated with

  5. Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium – Part 2: A pseudo-proxy study addressing the amplitude of solar forcing

    Directory of Open Access Journals (Sweden)

    A. Hind

    2012-08-01

    Full Text Available The statistical framework of Part 1 (Sundberg et al., 2012, for comparing ensemble simulation surface temperature output with temperature proxy and instrumental records, is implemented in a pseudo-proxy experiment. A set of previously published millennial forced simulations (Max Planck Institute – COSMOS, including both "low" and "high" solar radiative forcing histories together with other important forcings, was used to define "true" target temperatures as well as pseudo-proxy and pseudo-instrumental series. In a global land-only experiment, using annual mean temperatures at a 30-yr time resolution with realistic proxy noise levels, it was found that the low and high solar full-forcing simulations could be distinguished. In an additional experiment, where pseudo-proxies were created to reflect a current set of proxy locations and noise levels, the low and high solar forcing simulations could only be distinguished when the latter served as targets. To improve detectability of the low solar simulations, increasing the signal-to-noise ratio in local temperature proxies was more efficient than increasing the spatial coverage of the proxy network. The experiences gained here will be of guidance when these methods are applied to real proxy and instrumental data, for example when the aim is to distinguish which of the alternative solar forcing histories is most compatible with the observed/reconstructed climate.

  6. Estimating trends in the global mean temperature record

    Science.gov (United States)

    Poppick, Andrew; Moyer, Elisabeth J.; Stein, Michael L.

    2017-06-01

    Given uncertainties in physical theory and numerical climate simulations, the historical temperature record is often used as a source of empirical information about climate change. Many historical trend analyses appear to de-emphasize physical and statistical assumptions: examples include regression models that treat time rather than radiative forcing as the relevant covariate, and time series methods that account for internal variability in nonparametric rather than parametric ways. However, given a limited data record and the presence of internal variability, estimating radiatively forced temperature trends in the historical record necessarily requires some assumptions. Ostensibly empirical methods can also involve an inherent conflict in assumptions: they require data records that are short enough for naive trend models to be applicable, but long enough for long-timescale internal variability to be accounted for. In the context of global mean temperatures, empirical methods that appear to de-emphasize assumptions can therefore produce misleading inferences, because the trend over the twentieth century is complex and the scale of temporal correlation is long relative to the length of the data record. We illustrate here how a simple but physically motivated trend model can provide better-fitting and more broadly applicable trend estimates and can allow for a wider array of questions to be addressed. In particular, the model allows one to distinguish, within a single statistical framework, between uncertainties in the shorter-term vs. longer-term response to radiative forcing, with implications not only on historical trends but also on uncertainties in future projections. We also investigate the consequence on inferred uncertainties of the choice of a statistical description of internal variability. While nonparametric methods may seem to avoid making explicit assumptions, we demonstrate how even misspecified parametric statistical methods, if attuned to the

  7. Globorotalia truncatulinoides (dextral) Mg/Ca as a proxy for Gulf of Mexico winter mixed-layer temperature: evidence from a sediment trap in the northern Gulf of Mexico

    Science.gov (United States)

    Spear, Jessica W.; Poore, Richard Z.; Quinn, Terrence M.

    2011-01-01

    Three years of weekly- to biweekly-resolved sediment-trap data show that almost 90% of the total flux of tests of the planktic foraminifer Globorotalia truncatulinoides to sediments in the northern Gulf of Mexico occurs in January and February. Comparison of δ18O from tests of non-encrusted Gl. truncatulinoides in sediment-trap samples with calculated calcification depths indicates that the non-encrusted individuals secrete their test in the winter surface-mixed layer, most likely at the bottom of the surface mixed zone. Mg/Ca-temperature estimates from non-encrusted Gl. truncatulinoides in sediment-trap samples are consistent with observed temperatures at the calcification depths inferred from the δ18O data. In contrast, Mg/Ca-temperature estimates from encrusted Gl. truncatulinoides in sediment-trap samples indicate the crust is formed in cooler (deeper) waters. A preliminary study in a core recovered near the sediment-trap site demonstrates that non-encrusted and encrusted forms of Gl. truncatulinoides in sediment samples show a similar offset in Mg/Ca values as observed in sediment-trap samples. A short (~ 100 years) Mg/Ca record from non-encrusted Gl. truncatulinoides indicates a warming trend that coincides with a warming trend in mean-annual sea-surface temperature recorded by Mg/Ca in Globigerinoides ruber (white) from the same core. These findings suggest Mg/Ca from non-encrusted Gl. truncatulinoides has clear potential as a proxy for past winter mixed-layer temperature.

  8. Temperature and mineral dust variability recorded in two low-accumulation Alpine ice cores over the last millennium

    Directory of Open Access Journals (Sweden)

    P. Bohleber

    2018-01-01

    Full Text Available Among ice core drilling sites in the European Alps, Colle Gnifetti (CG is the only non-temperate glacier to offer climate records dating back at least 1000 years. This unique long-term archive is the result of an exceptionally low net accumulation driven by wind erosion and rapid annual layer thinning. However, the full exploitation of the CG time series has been hampered by considerable dating uncertainties and the seasonal summer bias in snow preservation. Using a new core drilled in 2013 we extend annual layer counting, for the first time at CG, over the last 1000 years and add additional constraints to the resulting age scale from radiocarbon dating. Based on this improved age scale, and using a multi-core approach with a neighbouring ice core, we explore the time series of stable water isotopes and the mineral dust proxies Ca2+ and insoluble particles. Also in our latest ice core we face the already known limitation to the quantitative use of the stable isotope variability based on a high and potentially non-stationary isotope/temperature sensitivity at CG. Decadal trends in Ca2+ reveal substantial agreement with instrumental temperature and are explored here as a potential site-specific supplement to the isotope-based temperature reconstruction. The observed coupling between temperature and Ca2+ trends likely results from snow preservation effects and the advection of dust-rich air masses coinciding with warm temperatures. We find that if calibrated against instrumental data, the Ca2+-based temperature reconstruction is in robust agreement with the latest proxy-based summer temperature reconstruction, including a Little Ice Age cold period as well as a medieval climate anomaly. Part of the medieval climate period around AD 1100–1200 clearly stands out through an increased occurrence of dust events, potentially resulting from a relative increase in meridional flow and/or dry conditions over the Mediterranean.

  9. Three centuries of temperature records in Scotland preserved in sclerochronological archives from freshwater pearl mussels, Margaritifera margaritifera (Linnaeus, 1758)

    Science.gov (United States)

    Pannell, C. L., ,, Dr; Fallick, A. E., ,, Prof.

    2009-04-01

    Bivalves are natural indicators of environmental variability as they reflect environmental conditions such as temperature in growth bands within the shell. During the winter period in temperate climes, shell growth ceases owing to the low water temperature and limited food supply. This hiatus is revealed by chemical staining as a very distinct etch-resistant band - termed the winter line. Winter lines alternate with less etch-resistant bands thus providing a chronology for any analyses which can be correlated to other proxy series and instrumental data. Freshwater pearl mussels have also been shown to form their shells in oxygen isotopic equilibrium with the ambient water thus fluctuations in water temperature can be constrained from the ^18Ocarbonatedata. As long as the date of collection is known, annual growth increments provide a precise dating tool for isotope samples and allow the allocation of precise calendar years to each part of the shell. Measurements of consecutive increments serve as records of isotopic composition from which derived temperatures may be correlated with other sample series and annual instrumental records, giving a high resolution proxy for temperature for a given region. ....... The use of live-collected M. margaritifera shells is now prohibited in the UK due to the mussel's rarity and its protection under the Wildlife and Countryside Act (1981) and the European Union Habitats and Species Directive (EUHSD). Museum collections of freshwater pearl mussels thus provide an invaluable resource, with many collections in UK museums having been live-collected during 19th century. As M. margaritifera is one of the longest-lived invertebrates, attaining an age of up to 140 years, sclerochronological and ^18Oaragonite data have the potential to provide terrestrial climate records on the centennial scale. The use of museum specimens has the potential to establish a composite three hundred year record of Scottish environmental change. Shells from

  10. Temperature dependence of bromine activation due to reaction of bromide with ozone in a proxy for organic aerosols and its importance for chemistry in surface snow.

    Science.gov (United States)

    Edebeli, Jacinta; Ammann, Markus; Gilgen, Anina; Trachsel, Jürg; Avak, Sven; Eichler, Anja; Schneebeli, Martin; Bartels-Rausch, Thorsten

    2017-04-01

    Tropospheric ozone depletion events (ODEs) via halogen activation are observed in both cold and warm climates [1-3]. Very recently, it was suggested that this multiphase halogen activation chemistry dominates in the tropical and subtropical upper troposphere [4]. These occurrences beg the question of temperature dependence of halogen activation in sea-salt aerosol, which are often mixtures of sea-salt and organic molecules [3, 5]. With the application of flow-tubes, the aim of this study is to investigate the temperature dependence of bromine activation via ozone interaction in a bromide containing film as a proxy for mixed organic - sea-salt aersol. Citric acid is used in this study as a hygroscopically characterized matrix and a proxy for oxidized organics, which is of relevance to atmospheric chemistry. Here, we present reactive ozone uptake measured between 258 and 289 K. The data show high reproducibility. With available knowledge, we have reproduced the measured uptake with modelled bulk uptake while accounting for temperature dependence of the substrate's properties as diffusivity, viscosity, and gas solubility. This work is part of a cross-disciplinary project with the aim to investigate the impact of metamorphism on impurity location in aging snow and its consequences for chemical reactivity. Metamorphism drastically shapes the structure and physical properties of snow, which has impacts on heat transfer, albedo, and avalanche formation. Such changes can be driven by water vapour fluxes in dry metamorphism with a mass turnover of as much as 60% per day - much greater than previously thought [6]. The consequences for atmospheric science are a current question of research [7]. Here, we show first results of a joint experiment to probe the re-distribution of impurities during snow metamorphism in artificial snow combined with an investigation of the samples structural changes. Future work is planned with the goal to investigate to which extend the observed re

  11. Estuarine Alkenones: A High-Resolution Record of Sea-Surface Temperature from Narragansett Bay over the Past Millennia

    Science.gov (United States)

    Salacup, J.; Farmer, J. R.; Herbert, T.; Prell, W. L.

    2009-12-01

    Here we present a Uk’37 sea-surface temperature (SST) reconstruction from Narragansett Bay, RI. We analyzed sediments from three geographically separated cores for Uk’37, the concentration of C37 alkenones (C37-total), widely accepted as a paleo-productivity proxy, and elemental carbon and nitrogen concentrations. Our age model suggests our archives cover at least the past 600 years with a sampling resolution of 6-8 years. In contrast to alkenone profiles reported from the much lower salinity Chesapeake Bay, the alkenone fingerprint in Narragansett Bay lacks significant contributions from the C37:4 ketone and is consistent with production by open-ocean haptophytes (in all likelihood, E. huxleyi). Comparison of the results from each of the three cores yields temperature offsets consistent with instrumental SST gradients within Narragansett Bay suggesting sedimentary alkenones were produced locally, rather than being produced in, and advected from, the nearby Atlantic Ocean. Absolute SSTs vary by up to 1°C on decadal timescales and by up to 3.5°C over the entire record. On centennial timescales, SSTs increase by ~0.5°C between ~1450 and 1600 before declining by 1-1.5°C between 1600 and the mid-1800s perhaps recording the local expression of the Little Ice Age. Productivity, inferred from C37-total, is steady throughout the Bay from ~1450 to ~1725. However, after 1725 concentrations increase in the upper Bay but not in the lower, suggesting changes in land-use and runoff may have influenced alkenone production. Sedimentary alkenones, synthesized by a limited number of coccolithophorids, are the basis of the Uk’37 SST proxy, traditionally employed in climate reconstructions from open-ocean sediments. This work suggests that alkenones preserved in shallow-water sediments, like those of Narragansett Bay, may provide a new opportunity for reconstructing estuarine and coastal temperatures in other muddy high-deposition-rate settings.

  12. An annually resolved marine proxy record for the 8.2K cold event from the northern North Sea based on bivalve shells

    Science.gov (United States)

    Butler, Paul; Estrella-Martínez, Juan; Scourse, James

    2017-04-01

    The so-called 8.2K cold event is a rapid cooling of about 6° +/- 2° recorded in the Greenland ice core record and thought to be a consequence of a freshwater pulse from the Laurentide ice sheet which reduced deepwater formation in the North Atlantic. In the Greenland ice cores the event is characterized by a maximum extent of 159 years and a central event lasting for 70 years. As discussed by Thomas et al (QSR, 2007), the low resolution and dating uncertainty of much palaeoclimate data makes it difficult to determine the rates of change and causal sequence that characterise the event at different locations. We present here a bivalve shell chronology based on four shells of Arctica islandica from the northern North Sea which (within radiocarbon uncertainty) is coeval with the 8.2K event recorded in the Greenland ice cores. The years of death of each shell based on radiocarbon analysis and crossmatching are 8094, 8134, 8147, and 8208 yrs BP (where "present" = AD 1950), with an associated radiocarbon uncertainty of +/-80 yrs, and their longevities are 106, 122, 112 and 79 years respectively. The total length of the chronology is 192 years (8286 - 8094 BP +/- 80 yrs). The most noticeable feature of the chronology is an 60-year period of increasing growth which may correspond to a similar period of decreasing ice accumulation in the GRIP (central Greenland) ice core record. We tentatively suggest that this reflects increasing food supply to the benthos as summer stratification is weakened by colder seawater temperatures. Stable isotope analyses (results expected to be available when this abstract is presented), will show changes at annual and seasonal resolution, potentially giving a very detailed insight into the causal factors associated with the 8.2K event and its impact in the northern North Sea.

  13. Assessing recent warming using instrumentally homogeneous sea surface temperature records.

    Science.gov (United States)

    Hausfather, Zeke; Cowtan, Kevin; Clarke, David C; Jacobs, Peter; Richardson, Mark; Rohde, Robert

    2017-01-01

    Sea surface temperature (SST) records are subject to potential biases due to changing instrumentation and measurement practices. Significant differences exist between commonly used composite SST reconstructions from the National Oceanic and Atmospheric Administration's Extended Reconstruction Sea Surface Temperature (ERSST), the Hadley Centre SST data set (HadSST3), and the Japanese Meteorological Agency's Centennial Observation-Based Estimates of SSTs (COBE-SST) from 2003 to the present. The update from ERSST version 3b to version 4 resulted in an increase in the operational SST trend estimate during the last 19 years from 0.07° to 0.12°C per decade, indicating a higher rate of warming in recent years. We show that ERSST version 4 trends generally agree with largely independent, near-global, and instrumentally homogeneous SST measurements from floating buoys, Argo floats, and radiometer-based satellite measurements that have been developed and deployed during the past two decades. We find a large cooling bias in ERSST version 3b and smaller but significant cooling biases in HadSST3 and COBE-SST from 2003 to the present, with respect to most series examined. These results suggest that reported rates of SST warming in recent years have been underestimated in these three data sets.

  14. Denali Ice Core Record of North Pacific Sea Surface Temperatures and Marine Primary Productivity

    Science.gov (United States)

    Polashenski, D.; Osterberg, E. C.; Kreutz, K. J.; Winski, D.; Wake, C. P.; Ferris, D. G.; Introne, D.; Campbell, S. W.

    2016-12-01

    Chemical analyses of precipitation preserved in glacial ice cores provide a unique opportunity to study changes in atmospheric circulation patterns and ocean surface conditions through time. In this study, we aim to investigate changes in both the physical and biological parameters of the north-central Pacific Ocean and Bering Sea over the twentieth century using the deuterium excess (d-excess) and methanesulfonic acid (MSA) records from the Mt. Hunter ice cores drilled in Denali National Park, Alaska. These parallel, 208 m-long ice cores were drilled to bedrock during the 2013 field season on the Mt. Hunter plateau (63° N, 151° W, 3,900 m above sea level) by a collaborative research team consisting of members from Dartmouth College and the Universities of Maine and New Hampshire. The cores were sampled on a continuous melter system at Dartmouth College and analyzed for the concentrations major ions (Dionex IC) and trace metals (Element2 ICPMS), and for stable water isotope ratios (Picarro). The depth-age scale has been accurately dated to 400 AD using annual layer counting of several chemical species and further validated using known historical volcanic eruptions and the Cesium-137 spike associated with nuclear weapons testing in 1963. We use HYSPLIT back trajectory modeling to identify likely source areas of moisture and aerosol MSA being transported to the core site. Satellite imagery allows for a direct comparison between chlorophyll a concentrations in these source areas and MSA concentrations in the core record. Preliminary analysis of chlorophyll a and MSA concentrations, both derived almost exclusively from marine biota, suggest that the Mt. Hunter ice cores reflect changes in North Pacific and Bering Sea marine primary productivity. Analysis of the water isotope and MSA data in conjunction with climate reanalysis products shows significant correlations (p<0.05) between d-excess and MSA in the ice record and sea surface temperatures in the Bering Sea and

  15. Munchausen syndrome by proxy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001555.htm Munchausen syndrome by proxy To use the sharing features on this page, please enable JavaScript. Munchausen syndrome by proxy is a mental illness and ...

  16. A multi-proxy lake core record from Lago Lungo, Rieti Basin, Lazio, Italy and its relation to human activities in the catchment during the last century

    Science.gov (United States)

    Noble, Paula; Tunno, Irene; Mensing, Scott; Piovesan, Gianluca

    2016-04-01

    The lakes of the Rieti Basin have experienced extensive human modification dating back to pre-Roman times, yet lake archives indicate that the most profound changes to the aquatic ecosystem have occurred during the last century. Analysis of the upper ˜120 cm segment of a sediment core from Lago Lungo, dating back to ˜1830 CE, show changes in water quality and hydrologic inflow largely attributed to 20th century reclamation and land use activities. Lago Lungo is a shallow, small, eutrophic, hard water lake situated in an intermontaine alluvial plain ˜90 km NE of Rome. It is one of several remnant lakes in a poorly drained wetland area fed by numerous springs. Reclamation activities over the last century have substantially altered the drainage network affecting water delivery to the lakes and their connectivity. There are 3 interesting signals in the core. First, small Stephanodiscus species, associated with hypereutrophic conditions, appear after 1950, peak ˜1990, and may be attributed to increased use of chemical fertilizers and intensification of local agriculture. Elemental proxies from scanning XRF data (abundances of Ti, Si/Ti, and Ca) are consistent with increased eutrophication starting ˜1950. A decline in Stephanodicsus after 1990 reflects some improvement to the water quality following the lake's incorporation into a nature preserve and creation of a narrow vegetation buffer. Intermittent water quality measurements from 1982 onward corroborate the changes in trophic status interpreted from the core record. Second, a large change in the core stratigraphy, elemental geochemistry, and diatom composition occurs ˜1940 and is associated with several major reclamation efforts, including the rerouting of the Santa Susanna channel, which redirected large volumes of artesian inflows away from the lakes and estuarine system. Upstream, dams on the Turano and Salto rivers were also constructed, further affecting hydrological inflows into the basin. From ˜1900

  17. Sub-fossils of cladocerans in the surface sediment of 135 lakes as proxies for community structure of zooplankton, fish abundance and lake temperature

    DEFF Research Database (Denmark)

    Jeppesen, E.; Jensen, J. P.; Lauridsen, T. L.

    2003-01-01

    to summer mean air temperature, and for Danish lakes also, albeit weakly, to fish CPUE but not to chlorophyll a. Apparently, temperature is the most important factor determining the ratio of parthenogenetic to ephippia producing specimens of Bosmina. We conclude that the sediment record of cladocerans......To elucidate the possibilities of using zooplankton remains in the surface sediment to describe present-days community structure and population dynamics of zooplankton, fish abundance and temperature, we compared contemporary data sampled in the pelagial during summer with the sediment record from......, which otherwise can be obtained only by long-term frequent contemporary sampling for several years. The contribution of Daphnia to the sum of Daphnia and Bosmina ephippia was negatively correlated with the abundance of fish expressed as catch per night in multi-mesh sized gill nets (CPUE). Yet, region...

  18. Data for evaluating the Sr/Ca temperature proxy with in-situ temperature in the western Atlantic coral Siderastrea siderea

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Massive corals are used as environmental recorders throughout the tropics and subtropics to study environmental variability during time periods preceding...

  19. Frequency of extreme daily temperatures (HadEX2) over Eurasia documented in a northern Red Sea coral oxygen isotope record during the last century

    Science.gov (United States)

    Ionita-Scholz, Monica; Felis, Thomas; Rimbu, Norel; Lohmann, Gerrit

    2017-04-01

    The potential of a bimonthly-resolved northern Red Sea coral δ18O record as an archive for the occurrence of extreme daily temperature phenomena over Eurasia during Northern Hemisphere winter is investigated for the 1901-1995 period using extreme indices provided by the HadEX2 dataset (e.g., frost days, ice days, cold nights and cold days). The coral δ18O record reflects a combined signal of temperature and salinity variations in the surface waters of the northern Red Sea, and has been previously shown to provide a proxy for atmospheric circulation changes over the Northern Hemisphere mid-latitudes at interannual to decadal time scales. Here we show, by applying composite analysis, that cooler/more arid (warmer/less arid) winter conditions in the northern Red Sea region, indicated by positive (negative) coral δ18O anomalies (January-February), are related to a strong (weak) Northern Hemisphere polar vortex and, as a consequence, to a decreased (increased) number of days characterized by very cold temperatures and frost over Scandinavia and Central Europe. This situation is associated with an increased (decreased) number of days characterized by very cold temperatures and frost over the Balkan region. The occurrence of these daily temperature extremes is modulated by the frequency of atmospheric blocking over the British Isles and Central Europe, and a shift in the direction of the North Atlantic storm tracks. Importantly, coral records provide a bimonthly to monthly resolution, compared to other high-resolution proxy records which have either an annual resolution (e.g., ice cores, varved sediments) or an annual resolution with a signal that is biased towards a specific season that in most cases is not winter (e.g., tree rings). We argue that bimonthly-resolved northern Red Sea coral δ18O records provide an archive of interannual to decadal variations in the occurrence of extreme daily temperature events over wintertime Eurasia prior to the start of instrumental

  20. Terrigenous Grain-size Record of the Newfoundland Ridge Contourite Drift, IODP Site U1411: The First Physical Proxy Record of North Atlantic Abyssal Current Intensity during the Eocene-Oligocene Transition

    Science.gov (United States)

    Chilton, K.; Romans, B.; Spray, J.; Wilson, P. A.; Bohaty, S. M.; Sanchez, T.

    2016-12-01

    Atlantic Meridional Ocean Circulation (AMOC) is a vital process that helps to regulate global climate and support marine ecosystems. The timing and nature of the shift to modern AMOC, and especially to deep-water formation in the North Atlantic, has been a topic of ongoing study, with the Eocene-Oligocene Transition (EOT, 34 Ma) being a potential focal point of this shift. However, the role played by abrupt EOT cooling in North Atlantic circulation remains unclear. Improved constraints on Paleogene circulation will provide insight into the sensitivity of AMOC to perturbations in global climate. We obtained grain-size data from the terrigenous fraction of the mud-dominated sediments of the Southeast Newfoundland Ridge contourite drift complex at IODP Site U1411, which is interpreted to have formed under the influence of the Deep Western Boundary Current. We analyzed 195 samples that span 150 m of stratigraphy from 36-26 Ma. The main objective was to use the `sortable silt' fraction (10-63 µm) to generate a record of relative change in bottom-current velocity. These data are complemented with a record of the abundance and size of lithogenic sand (>63 µm). Here we present U1411 sortable silt data as the first physical proxy record of abyssal current intensity in the North Atlantic, from late Eocene to mid Oligocene. Invigoration of North Atlantic deep circulation occurred gradually (over Myr timescales). We infer that deep circulation in the North Atlantic was not sensitive to the abrupt global cooling and Antarctic glaciation associated with the EOT. Rather, our data suggest that changes in North Atlantic circulation were likely governed by longer-term processes related to the opening of key tectonic gateways (i.e., the Greenland-Scotland-Faeroes Ridge in the North Atlantic, and the Drake and Tasman Passages in the Southern Ocean). Lithogenic sand is nearly absent in the Eocene and then systematically increases in abundance from the earliest Oligocene through the

  1. Shell architecture: a novel proxy for paleotemperature reconstructions?

    Science.gov (United States)

    Milano, Stefania; Nehrke, Gernot; Wanamaker, Alan D., Jr.; Witbaard, Rob; Schöne, Bernd R.

    2017-04-01

    Mollusk shells are unique high-resolution paleoenvironmental archives. Their geochemical properties, such as oxygen isotope composition (δ18Oshell) and element-to-calcium ratios, are routinely used to estimate past environmental conditions. However, the existing proxies have certain drawbacks that can affect paleoreconstruction robustness. For instance, the estimation of water temperature of brackish and near-shore environments can be biased by the interdependency of δ18Oshell from multiple environmental variables (water temperature and δ18Owater). Likely, the environmental signature can be masked by physiological processes responsible for the incorporation of trace elements into the shell. The present study evaluated the use of shell structural properties as alternative environmental proxies. The sensitivity of shell architecture at µm and nm-scale to the environment was tested. In particular, the relationship between water temperature and microstructure formation was investigated. To enable the detection of potential structural changes, the shells of the marine bivalves Cerastoderma edule and Arctica islandica were analyzed with Scanning Electron Microscopy (SEM), nanoindentation and Confocal Raman Microscopy (CRM). These techniques allow a quantitative approach to the microstructural analysis. Our results show that water temperature induces a clear response in shell microstructure. A significant alteration in the morphometric characteristics and crystallographic orientation of the structural units was observed. Our pilot study suggests that shell architecture records environmental information and it has potential to be used as novel temperature proxy in near-shore and open ocean habitats.

  2. Lithium in Brachiopods - proxy for seawater evolution?

    Science.gov (United States)

    Gaspers, Natalie; Magna, Tomas; Tomasovych, Adam; Henkel, Daniela

    2017-04-01

    Marine biogenic carbonates have the potential to serve as a proxy for evolution of seawater chemistry. In order to compile a record of the past and recent δ7Li in the oceans, foraminifera shells, scleractinian corals and belemnites have been used. However, only a foraminifera-based record appears to more accurately reflect the Li isotope composition of ocean water. At present, this record is available for the Cenozoic with implications for major events during this period of time, including K/T event [1]. A record for the entire Phanerozoic has not yet been obtained. In order to extend this record to the more distant past, Li elemental/isotope systematics of brachiopods were investigated because these marine animals were already present in Early Cambrian oceans and because they are less sensitive to diagenesis-induced modifications due to their shell mineralogy (low-Mg calcite). The preliminary data indicates a species-, temperature- and salinity-independent behavior of Li isotopes in brachiopod shells. Also, no vital effects have been observed for different shell parts. The consistent offset of -4‰ relative to modern seawater is in accordance with experimental data [2]. Further data are now being collected for Cenozoic specimens to more rigorously test brachiopods as possible archives of past seawater in comparison to the existing foraminiferal records. [1] Misra & Froelich (2012) Science 335, 818-823 [2] Marriott et al. (2004) Chem Geol 212, 5-15

  3. A comparison of PMIP2 model simulations and the MARGO proxy reconstruction for tropical sea surface temperatures at last glacial maximum

    Energy Technology Data Exchange (ETDEWEB)

    Otto-Bliesner, Bette L.; Brady, E.C. [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States); Schneider, Ralph; Weinelt, M. [Christian-Albrechts Universitaet, Institut fuer Geowissenschaften, Kiel (Germany); Kucera, M. [Eberhard-Karls Universitaet Tuebingen, Institut fuer Geowissenschaften, Tuebingen (Germany); Abe-Ouchi, A. [The University of Tokyo, Center for Climate System Research, Kashiwa (Japan); Bard, E. [CEREGE, College de France, CNRS, Universite Aix-Marseille, Aix-en-Provence (France); Braconnot, P.; Kageyama, M.; Marti, O.; Waelbroeck, C. [Unite mixte CEA-CNRS-UVSQ, Laboratoire des Sciences du Climat et de l' Environnement, Gif-sur-Yvette Cedex (France); Crucifix, M. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); Hewitt, C.D. [Met Office Hadley Centre, Exeter (United Kingdom); Paul, A. [Bremen University, Department of Geosciences, Bremen (Germany); Rosell-Mele, A. [Universitat Autonoma de Barcelona, ICREA and Institut de Ciencia i Tecnologia Ambientals, Barcelona (Spain); Weber, S.L. [Royal Netherlands Meteorological Institute (KNMI), De Bilt (Netherlands); Yu, Y. [Chinese Academy of Sciences, LASG, Institute of Atmospheric Physics, Beijing (China)

    2009-05-15

    Results from multiple model simulations are used to understand the tropical sea surface temperature (SST) response to the reduced greenhouse gas concentrations and large continental ice sheets of the last glacial maximum (LGM). We present LGM simulations from the Paleoclimate Modelling Intercomparison Project, Phase 2 (PMIP2) and compare these simulations to proxy data collated and harmonized within the Multiproxy Approach for the Reconstruction of the Glacial Ocean Surface Project (MARGO). Five atmosphere-ocean coupled climate models (AOGCMs) and one coupled model of intermediate complexity have PMIP2 ocean results available for LGM. The models give a range of tropical (defined for this paper as 15 S-15 N) SST cooling of 1.0-2.4 C, comparable to the MARGO estimate of annual cooling of 1.7{+-}1 C. The models simulate greater SST cooling in the tropical Atlantic than tropical Pacific, but interbasin and intrabasin variations of cooling are much smaller than those found in the MARGO reconstruction. The simulated tropical coolings are relatively insensitive to season, a feature also present in the MARGO transferred-based estimates calculated from planktonic foraminiferal assemblages for the Indian and Pacific Oceans. These assemblages indicate seasonality in cooling in the Atlantic basin, with greater cooling in northern summer than northern winter, not captured by the model simulations. Biases in the simulations of the tropical upwelling and thermocline found in the preindustrial control simulations remain for the LGM simulations and are partly responsible for the more homogeneous spatial and temporal LGM tropical cooling simulated by the models. The PMIP2 LGM simulations give estimates for the climate sensitivity parameter of 0.67 -0.83 C per Wm{sup -2}, which translates to equilibrium climate sensitivity for doubling of atmospheric CO{sub 2} of 2.6-3.1 C. (orig.)

  4. A Holocene lacustrine record in the central North Atlantic: proxies for volcanic activity, short-term NAO mode variability, and long-term precipitation changes

    Science.gov (United States)

    Björck, Svante; Rittenour, Tammy; Rosén, Peter; França, Zilda; Möller, Per; Snowball, Ian; Wastegård, Stefan; Bennike, Ole; Kromer, Bernd

    2006-01-01

    Lake and peat corings on three Azores islands in the central North Atlantic, resulted in the discovery of a 6000 year long lacustrine sequence in a small crater lake, Lake Caveiro, on the island of Pico. This island is dominated by Pico mountain (2351 m), Portugal's highest mountain, and the lake site is situated at 903 m asl. Two sediment profiles, one central and one littoral, were sampled. Due to large facial shifts and disconformities in the littoral cores the analyses were concentrated on the central core; only the earliest 1000 years of the littoral core were studied to complement the central profile. We used sedimentology, geochemistry, diatom analyses, magnetic properties, and multivariate statistics, together with 14C and 210Pb dating techniques, to analyse the environmental history of the lake. Volcanic activity seems to have had a dominating impact on sediment changes and partly also on the diatom assemblages; a large number of tephras are found and seem to be connected with large (diatom) inferred pH variations. However, by a combination of methods, including multivariate techniques, we infer that precipitation changes can be detected through the volcanic noise. In the youngest part of the record (AD 1600-2000), with its decadal resolution, these humidity variations seem partly related to shifts in dominating NAO mode. The more long-term precipitation changes further back in time (350-5100 cal yr BP) roughly correspond to the well-known North Atlantic drift-ice variations as well as other North Atlantic records; low precipitation during drift-ice periods. We think these alterations were driven by changes in the thermohaline circulation as large-scale equivalences to the Great Salt Anomaly; low sea surface temperatures and changes in circulation patterns of the central North Atlantic decreased the regional precipitation. Cooler/drier periods occurred 400-800, 1300-1800, 2600-3000, 3300-3400 and possibly also 4400-4600 cal yr BP, while 300-400, 900

  5. Marine proxy evidence linking decadal North Pacific and Atlantic climate

    Energy Technology Data Exchange (ETDEWEB)

    Hetzinger, S. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); Halfar, J. [University of Toronto Mississauga, CPS-Department, Mississauga, ON (Canada); Mecking, J.V.; Keenlyside, N.S. [Leibniz Institute of Marine Sciences, IFM-GEOMAR, Kiel (Germany); University of Bergen, Geophysical Institute and Bjerknes Centre for Climate Research, Bergen (Norway); Kronz, A. [University of Goettingen, Geowissenschaftliches Zentrum, Goettingen (Germany); Steneck, R.S. [University of Maine, Darling Marine Center, Walpole, ME (United States); Adey, W.H. [Smithsonian Institution, Department of Botany, Washington, DC (United States); Lebednik, P.A. [ARCADIS U.S. Inc., Walnut Creek, CA (United States)

    2012-09-15

    Decadal- to multidecadal variability in the extra-tropical North Pacific is evident in 20th century instrumental records and has significant impacts on Northern Hemisphere climate and marine ecosystems. Several studies have discussed a potential linkage between North Pacific and Atlantic climate on various time scales. On decadal time scales no relationship could be confirmed, potentially due to sparse instrumental observations before 1950. Proxy data are limited and no multi-centennial high-resolution marine geochemical proxy records are available from the subarctic North Pacific. Here we present an annually-resolved record (1818-1967) of Mg/Ca variations from a North Pacific/Bering Sea coralline alga that extends our knowledge in this region beyond available data. It shows for the first time a statistically significant link between decadal fluctuations in sea-level pressure in the North Pacific and North Atlantic. The record is a lagged proxy for decadal-scale variations of the Aleutian Low. It is significantly related to regional sea surface temperature and the North Atlantic Oscillation (NAO) index in late boreal winter on these time scales. Our data show that on decadal time scales a weaker Aleutian Low precedes a negative NAO by several years. This atmospheric link can explain the coherence of decadal North Pacific and Atlantic Multidecadal Variability, as suggested by earlier studies using climate models and limited instrumental data. (orig.)

  6. High-Arctic climate conditions for the last 7000 years inferred from multi-proxy analysis of the Bliss Lake record, North Greenland

    DEFF Research Database (Denmark)

    Olsen, Jesper; Kjær, Kurt H.; Funder, Svend Visby

    2012-01-01

    , Peary Land, Greenland. The early Holocene (10 850–10 480 cal. a BP) is characterized by increased erosion and gradually more marine conditions. Full marine conditions developed from 10 480 cal. a BP until the lake was isolated at 7220 cal. a BP. From its marine isolation at 7220 cal. a BP Bliss Lake...... becomes a lacustrine environment. Evidence from geochemical proxies (δ13C and total organic carbon) suggests that warmer conditions prevailed between 7220 and 6500 cal. a BP, corresponding to the Holocene thermal maximum, and from 3300 until 910 cal. a BP. From 850 to 500 cal. a BP colder climate...

  7. Here be web proxies

    DEFF Research Database (Denmark)

    Weaver, Nicholas; Kreibich, Christian; Dam, Martin

    2014-01-01

    HTTP proxies serve numerous roles, from performance enhancement to access control to network censorship, but often operate stealthily without explicitly indicating their presence to the communicating endpoints. In this paper we present an analysis of the evidence of proxying manifest in executions...... of the ICSI Netalyzr spanning 646,000 distinct IP addresses ("clients"). To identify proxies we employ a range of detectors at the transport and application layer, and report in detail on the extent to which they allow us to fingerprint and map proxies to their likely intended uses. We also analyze 17...

  8. Ranges of moisture-source temperature estimated from Antarctic ice cores stable isotope records over glacial–interglacial cycles

    Directory of Open Access Journals (Sweden)

    R. Uemura

    2012-06-01

    Full Text Available A single isotope ratio (δD or δ18O of water is widely used as an air-temperature proxy in Antarctic ice core records. These isotope ratios, however, do not solely depend on air-temperature but also on the extent of distillation of heavy isotopes out of atmospheric water vapor from an oceanic moisture source to a precipitation site. The temperature changes at the oceanic moisture source (Δ Tsource and at the precipitation site (Δ Tsite can be retrieved by using deuterium-excess (d data. A new d record from Dome Fuji, Antarctica spanning the past 360 000 yr is presented and compared with records from Vostok and EPICA Dome C ice cores. In previous studies, to retrieve Δ Tsource and Δ Tsite information, different linear regression equations were proposed using theoretical isotope distillation models. A major source of uncertainty lies in the coefficient of regression, βsite which is related to the sensitivity of d to Δ Tsite. We show that different ranges of temperature and selections of isotopic model outputs may increase the value of βsite by more than a factor of two. To explore the impacts of this coefficient on reconstructed temperatures, we apply for the first time the exact same methodology to the isotope records from the three Antarctica ice cores. We show that uncertainties in the βsite coefficient strongly affect (i the glacial–interglacial magnitude of Δ Tsource; (ii the imprint of obliquity in Δ Tsource and in the site-source temperature gradient. By contrast, we highlight the robustness of Δ Tsite reconstruction using water isotopes records.

  9. NOAA Climate Data Record (CDR) of Atmospheric Layer Temperatures, Version 3.3

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Atmospheric Layer Temperature Climate Data Record (CDR) dataset is a monthly analysis of the tropospheric and stratospheric data using temperature sounding...

  10. BASE Temperature Data Record (TDR) from the SSM/I and SSMIS Sensors, CSU Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The BASE Temperature Data Record (TDR) dataset from Colorado State University (CSU) is a collection of the raw unprocessed antenna temperature data that has been...

  11. Earlywood vessels of Castanea sativa record temperature before their formation.

    Science.gov (United States)

    Fonti, Patrick; Solomonoff, Natalie; García-González, Ignacio

    2007-01-01

    The aim of this study was to identify the climatic signal contained in the earlywood vessel size of the ring-porous chestnut (Castanea sativa) and the physiological processes involved in the underlying mechanisms. In order to assign the encoded signal to a specific physiological process, bud phenology and vessel formation were monitored along an elevation transect and chronologies of the size of the first row of earlywood vessels were retrospectively correlated with 40 yr of early spring temperatures. The first vessels appeared in late April to early May, after encoding both a negative temperature signal in February-March (during tree quiescence) and a positive temperature signal in early April (at the time of resumption of shoot growth). We hypothesize that February and March temperatures affect cambial sensitivity to auxin, preconditioning tree responses later in the season. Furthermore, April temperature is related to tree activation whereby new hormone production fosters vessel expansion.

  12. Analysis of global and hemispheric temperature records and prognosis

    Science.gov (United States)

    Werner, Rolf; Valev, Dimitar; Danov, Dimitar; Guineva, Veneta; Kirillov, Andrey

    2015-06-01

    Climate changes are connected to long term variations of global and hemispheric temperatures, which are important for the work out of socio-political strategy for the near future. In the paper the annual temperature time series are modeled by linear multiple regression to identify important climate forcings including external climate factors such as atmospheric CO2 content, volcanic emissions, and the total solar irradiation as well as internal factors such as El Niño-Southern oscillation, Pacific decadal oscillation and Atlantic multidecadal oscillation. Adjusted temperatures were determined by removal of all significant influences except CO2. The adjusted temperatures follow a linear dependence toward the logarithm of the CO2 content, and the coefficient of determination is about 0.91. The evolution of the adjusted temperatures suggests that the warming due to CO2 from the beginning of the studied here time interval in 1900 has never stopped and is going on up to now. The global warming rate deduced from the adjusted temperatures since 1980 is about 0.14 ± 0.02 °C/decade. The warming rate reported in the IPCC assessment report 4 based on observed global surface temperature set is about 20% higher, due to the warming by the Atlantic multidecadal oscillation additional to the anthropogenic warming. The predicted temperature evolution based on long time changes of CO2 and the Atlantic multidecadal oscillation index shows that the Northern Hemispheric temperatures are modulated by the Atlantic multidecadal oscillation influence and will not change significantly to about 2040, after that they will increase speedily, just like during the last decades of the past century. The temperatures of the Southern Hemisphere will increase almost linearly and don't show significant periodic changes due to Atlantic multidecadal oscillation. The concrete warming rates of course are strongly depending on the future atmospheric CO2 content.

  13. Jemen - the Proxy War

    Directory of Open Access Journals (Sweden)

    Magdalena El Ghamari

    2015-12-01

    Full Text Available The military operation in Yemen is significant departure from Saudi Arabia's foreign policy tradition and customs. Riyadh has always relied on three strategies to pursue its interests abroad: wealth, establish a global network and muslim education and diplomacy and meadiation. The term "proxy war" has experienced a new popularity in stories on the Middle East. A proxy war is two opposing countries avoiding direct war, and instead supporting combatants that serve their interests. In some occasions, one country is a direct combatant whilst the other supporting its enemy. Various news sources began using the term to describe the conflict in Yemen immediately, as if on cue, after Saudi Arabia launched its bombing campaign against Houthi targets in Yemen on 25 March 2015. This is the reason, why author try to answer for following questions: Is the Yemen Conflict Devolves into Proxy War? and Who's fighting whom in Yemen's proxy war?" Research area includes the problem of proxy war in the Middle East. For sure, the real problem of proxy war must begin with the fact that the United States and its NATO allies opened the floodgates for regional proxy wars by the two major wars for regime change: in Iraq and Libya. Those two destabilising wars provided opportunities and motives for Sunni states across the Middle East to pursue their own sectarian and political power objectives through "proxy war".

  14. Middle to Late Holocene Hydroclimate Variability on the Tibetan Plateau Inferred from a Multi-Proxy Lake Sediment Record, Galang Co, Southeastern Tibet.

    Science.gov (United States)

    Perello, M. M.; Bird, B. W.; Lei, Y.; Polissar, P. J.; Thompson, L. G.; Yao, T.

    2016-12-01

    The Indian summer monsoon (ISM) is the primary source of water for Southeastern Asia and a population of over a billion people. Reductions in rainfall and the monsoon season have the potential for dramatic impacts on regions population, but climate records for this system are limited in frequency and scale. The ISM is the primary source for the Nyainqêntanglha mountain range in eastern Tibetan Plateau producing a signal that can be construed directly to the ISM. Predicting variability in the ISM is limited when reliant on modern monitoring and as such paleoclimate records are needed to expand these records to assess long-term variability. A transect of lakes in the Nyainqêntanglha region aims to provide new Holocene era climate records that resolve ISM variability at a decadal scale. Previously unstudied lake, Galang Co, is at a relatively low elevation (2800 m) in a heavily-forested watershed in the Lhasa River valley. In contrast, most lakes studied are at higher elevations with a respective arid climate. Galang provides a more thorough analysis of how the monsoon strength varies spatially through the eastern plateau. Two Livingstone and three surface cores along with surface sediments were collected in June 2015. Basal ages show that the record spans over 7,400 years before present. Initial analyses of sediments has shown trends in sedimentology, grain size, and organic carbon matter that are inferred to represent transitions from in lake levels ranging from a shallow bog to a deep lake. This record is compared with existing paleo hydroclimate records from surrounding lakes (including Nir'Pa Co and Paru Co from this same project) to make inferences about monsoon strength and variability. Future research will incorporate terrestrial leaf-wax isotopes and diatom assemblages to expand this record. Records produced from this and similar projects have the potential to constrain climate models focusing on how the ISM will vary due to changing climate.

  15. High-resolution records of the beryllium-10 solar activity proxy in ice from Law Dome, East Antarctica: measurement, reproducibility and principal trends

    Directory of Open Access Journals (Sweden)

    J. B. Pedro

    2011-07-01

    Full Text Available Three near-monthly resolution 10Be records are presented from the Dome Summit South (DSS ice core site, Law Dome, East Antarctica. The chemical preparation and Accelerator Mass Spectrometer (AMS measurement of these records is described. The reproducibility of 10Be records at DSS is assessed through intercomparison of the ice core data with data from two previously published and contemporaneous snow pits. We find generally good agreement between the five records, comparable to that observed between other trace chemical records from the site. This result allays concerns raised by a previous Antarctic study (Moraal et al., 2005 about poor reproducibility of ice core 10Be records. A single composite series is constructed from the three ice cores providing a monthly-resolved record of 10Be concentrations at DSS over the past decade (1999 to 2009. To our knowledge, this is the first published ice core data spanning the recent exceptional solar minimum of solar cycle 23. 10Be concentrations are significantly correlated to the cosmic ray flux recorded by the McMurdo neutron monitor (rxy = 0.64, with 95 % CI of 0.53 to 0.71, suggesting that solar modulation of the atmospheric production rate may explain up to ~40 % of the variance in 10Be concentrations at DSS. Sharp concentration peaks occur in most years during the summer-to-autumn, possibly caused by stratospheric incursions. Our results underscore the presence of both production and meteorological signals in ice core 10Be data.

  16. Pseudo-proxy evaluation of climate field reconstruction methods of North Atlantic climate based on an annually resolved marine proxy network

    Science.gov (United States)

    Pyrina, Maria; Wagner, Sebastian; Zorita, Eduardo

    2017-10-01

    Two statistical methods are tested to reconstruct the interannual variations in past sea surface temperatures (SSTs) of the North Atlantic (NA) Ocean over the past millennium based on annually resolved and absolutely dated marine proxy records of the bivalve mollusk Arctica islandica. The methods are tested in a pseudo-proxy experiment (PPE) setup using state-of-the-art climate models (CMIP5 Earth system models) and reanalysis data from the COBE2 SST data set. The methods were applied in the virtual reality provided by global climate simulations and reanalysis data to reconstruct the past NA SSTs using pseudo-proxy records that mimic the statistical characteristics and network of Arctica islandica. The multivariate linear regression methods evaluated here are principal component regression and canonical correlation analysis. Differences in the skill of the climate field reconstruction (CFR) are assessed according to different calibration periods and different proxy locations within the NA basin. The choice of the climate model used as a surrogate reality in the PPE has a more profound effect on the CFR skill than the calibration period and the statistical reconstruction method. The differences between the two methods are clearer for the MPI-ESM model due to its higher spatial resolution in the NA basin. The pseudo-proxy results of the CCSM4 model are closer to the pseudo-proxy results based on the reanalysis data set COBE2. Conducting PPEs using noise-contaminated pseudo-proxies instead of noise-free pseudo-proxies is important for the evaluation of the methods, as more spatial differences in the reconstruction skill are revealed. Both methods are appropriate for the reconstruction of the temporal evolution of the NA SSTs, even though they lead to a great loss of variance away from the proxy sites. Under reasonable assumptions about the characteristics of the non-climate noise in the proxy records, our results show that the marine network of Arctica islandica can

  17. Pseudo-proxy evaluation of climate field reconstruction methods of North Atlantic climate based on an annually resolved marine proxy network

    Directory of Open Access Journals (Sweden)

    M. Pyrina

    2017-10-01

    Full Text Available Two statistical methods are tested to reconstruct the interannual variations in past sea surface temperatures (SSTs of the North Atlantic (NA Ocean over the past millennium based on annually resolved and absolutely dated marine proxy records of the bivalve mollusk Arctica islandica. The methods are tested in a pseudo-proxy experiment (PPE setup using state-of-the-art climate models (CMIP5 Earth system models and reanalysis data from the COBE2 SST data set. The methods were applied in the virtual reality provided by global climate simulations and reanalysis data to reconstruct the past NA SSTs using pseudo-proxy records that mimic the statistical characteristics and network of Arctica islandica. The multivariate linear regression methods evaluated here are principal component regression and canonical correlation analysis. Differences in the skill of the climate field reconstruction (CFR are assessed according to different calibration periods and different proxy locations within the NA basin. The choice of the climate model used as a surrogate reality in the PPE has a more profound effect on the CFR skill than the calibration period and the statistical reconstruction method. The differences between the two methods are clearer for the MPI-ESM model due to its higher spatial resolution in the NA basin. The pseudo-proxy results of the CCSM4 model are closer to the pseudo-proxy results based on the reanalysis data set COBE2. Conducting PPEs using noise-contaminated pseudo-proxies instead of noise-free pseudo-proxies is important for the evaluation of the methods, as more spatial differences in the reconstruction skill are revealed. Both methods are appropriate for the reconstruction of the temporal evolution of the NA SSTs, even though they lead to a great loss of variance away from the proxy sites. Under reasonable assumptions about the characteristics of the non-climate noise in the proxy records, our results show that the marine network of Arctica

  18. Upper Pleistocene and Holocene palaeoenvironmental records in Cueva Mayor karst (Atapuerca, Spain from different proxies: speleothem crystal fabrics, palynology and archaeology.

    Directory of Open Access Journals (Sweden)

    Virginia Martínez-Pillado

    2014-01-01

    Full Text Available The Cueva Mayor karst system of Atapuerca, in Northern Spain, hosts a highly significant record of human occupation from the Pleistocene. The climatic context of the human activities during the Pleistocene-Holocene for this inland site has not been well constrained, since existing records of the palaeoclimatic evolution of the Northern Iberian Peninsula are from more distal coastal and high-elevation sites. In this study, we interpret the palaeoenvironmental information recorded on the petrography of a stalagmite and the pollen spectra of the Sierra de Atapuerca karst system during the last 20 kyr. The integration of both types of records has allowed us to define four palaeoenvironmental stages. During the Upper Pleistocene and until 12.8 kyr BP, the climate was cold and dry, toward the end of the interval evolving to wetter and warmer conditions. From 12.8 to 7.7 kyr BP, during the Mesolithic-Neolithic, a major erosion event in both records marks the Pleistocene-Holocene transition. Around 5.9 kyr BP, the Late Neolithic, environmental conditions indicate a climatic optimum with a marked seasonality. The environmental conditions became drier from 4.2 kyr BP until the present, with a decrease in the woodlands. This aridity signal might be amplified by the impact of a more intense human agricultural activity after 3.1 kyr BP, during the Bronze Age.

  19. Understanding Abrupt, Natural Climate Variability Post-Industrial Revolution from the Subtropical Eastern Pacific: A Novel High Resolution Alkenone-derived Sea Surface Temperature Record

    Science.gov (United States)

    Kelly, C. S.; O'Mara, N. A.; Herbert, T.; Abella-Gutiérrez, J. L.; Herguera, J. C.

    2015-12-01

    Despite the ocean's importance in global biogeochemical feedbacks and heat storage, there is still a paucity of decadally-resolved sea surface temperature (SST) records to complement lacustrine and dendrological records of recent paleoclimate. Natural climate variability on multidecadal timescales is dominated by internal ocean circulation dynamics and feedbacks, and it is therefore imperative to employ marine proxies to reconstruct high resolution climate change. The timescales of this ocean-induced natural climate variability can be broken down into a few characteristic climate modes. Pressing questions about these modes include their stationarity in frequency and amplitude over time, in addition to the hypothesis that anthropogenic climate change has altered their behavior in comparison to natural variability. To pursue these questions, we must discern and analyze suitable climate archives in regions where modes of interest dominate modern climate variability. The region of Baja California, Mexico exhibits exceptional teleconnection to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Local, dramatic effects of ENSO and PDO on the marine biology and economy underline the importance of regional paleoclimate records from the Baja peninsula. Here, we present a high-resolution alkenone-derived SST reconstruction from the Industrial Revolution through the year 2000 by analysis of laminated box and Kasten sediment cores at Site PCM 00-78 (25.18°N, 112.66°W) in the subtropical eastern Pacific at a depth of 540 meters. Our SST record corresponds with NOAA extended reconstructed sea surface temperature, providing a robust basis for organic geochemical marine climatic reconstructions on timescales usually accessible only through speleothems, coral density bands, tree rings, and the like. Accordingly, based on this comparison to the historical data we expect our SST record may provide a more robust record of inter and multidecadal

  20. Jemen - the Proxy War

    OpenAIRE

    Magdalena El Ghamari

    2015-01-01

    The military operation in Yemen is significant departure from Saudi Arabia's foreign policy tradition and customs. Riyadh has always relied on three strategies to pursue its interests abroad: wealth, establish a global network and muslim education and diplomacy and meadiation. The term "proxy war" has experienced a new popularity in stories on the Middle East. A proxy war is two opposing countries avoiding direct war, and instead supporting combatants that serve their interests. In some occas...

  1. A high-elevation, multi-proxy biotic and environmental record of MIS 6-4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    Science.gov (United States)

    Miller, Ian M.; Pigati, Jeffrey S.; Anderson, R. Scott; Johnson, Kirk R.; Mahan, Shannon; Ager, Thomas A.; Baker, Richard G.; Blaauw, Maarten; Bright, Jordon; Brown, Peter M.; Bryant, Bruce; Calamari, Zachary T.; Carrara, Paul E.; Michael D., Cherney; Demboski, John R.; Elias, Scott A.; Fisher, Daniel C.; Gray, Harrison J.; Haskett, Danielle R.; Honke, Jeffrey S.; Jackson, Stephen T.; Jiménez-Moreno, Gonzalo; Kline, Douglas; Leonard, Eric M.; Lifton, Nathaniel A.; Lucking, Carol; McDonald, H. Gregory; Miller, Dane M.; Muhs, Daniel R.; Nash, Stephen E.; Newton, Cody; Paces, James B.; Petrie, Lesley; Plummer, Mitchell A.; Porinchu, David F.; Rountrey, Adam N.; Scott, Eric; Sertich, Joseph J. W.; Sharpe, Saxon E.; Skipp, Gary L.; Strickland, Laura E.; Stucky, Richard K.; Thompson, Robert S.; Wilson, Jim

    2014-01-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~ 140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5.

  2. A high-elevation, multi-proxy biotic and environmental record of MIS 6–4 from the Ziegler Reservoir fossil site, Snowmass Village, Colorado, USA

    Energy Technology Data Exchange (ETDEWEB)

    Ian M. Miller; Mitchell A. Plummer; Various Others

    2014-10-01

    In North America, terrestrial records of biodiversity and climate change that span Marine Oxygen Isotope Stage (MIS) 5 are rare. Where found, they provide insight into how the coupling of the ocean–atmosphere system is manifested in biotic and environmental records and how the biosphere responds to climate change. In 2010–2011, construction at Ziegler Reservoir near Snowmass Village, Colorado (USA) revealed a nearly continuous, lacustrine/wetland sedimentary sequence that preserved evidence of past plant communities between ~140 and 55 ka, including all of MIS 5. At an elevation of 2705 m, the Ziegler Reservoir fossil site also contained thousands of well-preserved bones of late Pleistocene megafauna, including mastodons, mammoths, ground sloths, horses, camels, deer, bison, black bear, coyotes, and bighorn sheep. In addition, the site contained more than 26,000 bones from at least 30 species of small animals including salamanders, otters, muskrats, minks, rabbits, beavers, frogs, lizards, snakes, fish, and birds. The combination of macro- and micro-vertebrates, invertebrates, terrestrial and aquatic plant macrofossils, a detailed pollen record, and a robust, directly dated stratigraphic framework shows that high-elevation ecosystems in the Rocky Mountains of Colorado are climatically sensitive and varied dramatically throughout MIS 5

  3. Single-atom reversible recording at room temperature

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Stokbro, Kurt; Lin, Rong

    2001-01-01

    A single hydrogen atom can be reversibly switched between two symmetric sites on a silicon dimer at the surface of Si(100) using a scanning tunnelling microscope (STM). This is a model binary switch for silicon-based atom-scale reversible data storage at room temperature. In this paper we...... is of crucial importance. With our equipment it was possible to create a row of four switches in a controlled way.(Some figures in this article are in colour only in the electronic version)....

  4. Proxy Records of the Indonesian Low and the El Ni{tilde n}o-Southern Oscillation (ENSO) from Stable Isotope Measurements of Indonesian Reef Corals

    Energy Technology Data Exchange (ETDEWEB)

    Moore, M.D.

    1995-12-31

    The Earth`s largest atmospheric convective center is the Indonesian Low. It generates the Australasian monsoon, drives the zonal tropospheric Walker Circulation, and is implicated in the genesis of the El Nino-Southern Oscillation (ENSO). The long-term variability of the Indonesian Low is poorly characterized, yet such information is crucial for evaluating whether changes in the strength and frequency of ENSO events are a possible manifestation of global warming. Stable oxygen isotope ratios ({delta}{sup 18}O) in shallow-water reef coral skeletons track topical convective activity over hundreds of years because the input of isotopically-depleted rainwater dilutes seawater {delta}{sup 18}O. Corals also impose a temperature-dependent fractionation on {delta}{sup 18}O, but where annual rainfall is high and sea surface temperature (SST) variability is low the freshwater flux effect dominates.

  5. Consecutive record-breaking high temperatures marked the handover from hiatus to accelerated warming

    Science.gov (United States)

    Su, Jingzhi; Zhang, Renhe; Wang, Huijun

    2017-03-01

    Closely following the hiatus warming period, two astonishing high temperature records reached in 2014 and 2015 consecutively. To investigate the occurrence features of record-breaking high temperatures in recent years, a new index focusing the frequency of the top 10 high annual mean temperatures was defined in this study. Analyses based on this index shown that record-breaking high temperatures occurred over most regions of the globe with a salient increasing trend after 1960 s, even during the so-called hiatus period. Overlapped on the ongoing background warming trend and the interdecadal climate variabilities, the El Niño events, particularly the strong ones, can make a significant contribution to the occurrence of high temperatures on interannual timescale. High temperatures associated with El Niño events mainly occurred during the winter annual period. As the Pacific Decadal Oscillation (PDO) struggled back to its positive phase since 2014, the global warming returned back to a new accelerated warming period, marked by the record-breaking high temperatures in 2014. Intensified by the super strong El Niño, successive high records occurred in 2015 and 2016. Higher frequencies of record high temperatures would occur in the near future because the PDO tends to maintain a continuously positive phase.

  6. Consecutive record-breaking high temperatures marked the handover from hiatus to accelerated warming.

    Science.gov (United States)

    Su, Jingzhi; Zhang, Renhe; Wang, Huijun

    2017-03-03

    Closely following the hiatus warming period, two astonishing high temperature records reached in 2014 and 2015 consecutively. To investigate the occurrence features of record-breaking high temperatures in recent years, a new index focusing the frequency of the top 10 high annual mean temperatures was defined in this study. Analyses based on this index shown that record-breaking high temperatures occurred over most regions of the globe with a salient increasing trend after 1960 s, even during the so-called hiatus period. Overlapped on the ongoing background warming trend and the interdecadal climate variabilities, the El Niño events, particularly the strong ones, can make a significant contribution to the occurrence of high temperatures on interannual timescale. High temperatures associated with El Niño events mainly occurred during the winter annual period. As the Pacific Decadal Oscillation (PDO) struggled back to its positive phase since 2014, the global warming returned back to a new accelerated warming period, marked by the record-breaking high temperatures in 2014. Intensified by the super strong El Niño, successive high records occurred in 2015 and 2016. Higher frequencies of record high temperatures would occur in the near future because the PDO tends to maintain a continuously positive phase.

  7. A 1200-year proxy record of hurricanes and fires from the Gulf of Mexico coast: Testing the hypothesis of hurricane-fire interactions

    Science.gov (United States)

    Liu, Kam-biu; Lu, Houyuan; Shen, Caiming

    2008-01-01

    We present here the first high-resolution pollen record of vegetation response to interactions of hurricane and fire disturbances over the past 1200 yr from a small lake in Alabama on the Gulf of Mexico coast. The paleotempestological record inferred from the overwash sand layers suggests that the Alabama coast was directly struck by Saffir-Simpson category 4 or 5 hurricanes twice during the last 1200 yr, around 1170 and 860 cal yr BP, suggesting an annual landfall probability of 0.17% for these intense hurricanes. The charcoal data suggest that intense fires occurred after each of these hurricanes. The pollen data suggest that populations of halophytic plants (Chenopodiaceae) and heliophytic shrubs ( Myrica) expanded after the hurricane strikes, probably due to saltwater intrusion into the marshes and soil salinization caused by overwash processes. Populations of pines ( Pinus sp.) decreased significantly after each intense hurricane and the ensuing intense fire, suggesting that repeated hurricane-fire interactions resulted in high tree mortality and probably impeded recruitment and recovery. Our data support the hypothesis that the likelihood and intensity of fire increased significantly after a major hurricane, producing responses by vegetation that are more complex and unpredictable than if the disturbance agents were acting singly and independently.

  8. A 2650-year-long record of environmental change from northern Yellowstone National Park based on a comparison of multiple proxy data

    Science.gov (United States)

    Whitlock, C.; Dean, W.; Rosenbaum, J.; Stevens, L.; Fritz, S.; Bracht, B.; Power, M.

    2008-01-01

    Geochemical, stable-isotope, pollen, charcoal, and diatom records were analyzed at high-resolution in cores obtained from Crevice Lake, a varved-sediment lake in northern Yellowstone National Park. The objective was to reconstruct the ecohydrologic, vegetation, and fire history of the watershed for the last 2650 years to better understand past climate variations at the forest-steppe transition. The data suggest a period of limited bottom-water anoxia, relatively wet winters, and cool springs and summers from 2650 to 2100 cal yr BP (700-150 BC). Dry warm conditions occurred between 2100 and 850-800 cal yr BP (150 BC and AD 1100-1150), when the lake was anoxic, winter precipitation was low, and summer stratification was protracted. The data are consistent with overall warmer/drier conditions during the Medieval Climate Anomaly, although they suggest a shift towards wetter winters within that period. The period from 850 to 800 cal yr BP (AD 1100-1150) to 250 cal yr BP (AD 1700) was characterized by greater water-column mixing and cooler spring/summer conditions than before. In addition, fire activity shifted towards infrequent large events and pollen production was low. From 250 to 150 cal yr BP (AD 1700-1800), winter precipitation was moderate compared to previous conditions, and the lake was again stratified, suggesting warm summers. Between 150 and 42 cal yr BP (AD 1800-1908), winter precipitation increased and spring and summer conditions became moderate. Metal pollution, probably from regional mining operations, is evident in the 1870s. Large fires occurred between ca. 1800-1880, but in general the forests were more closed than before. The Crevice Lake record suggests that the last 150 years of Yellowstone's environmental history were characterized by intermediate conditions when compared with the previous 2500 years. ?? 2007 Elsevier Ltd and INQUA.

  9. NOAA Climate Data Record (CDR) of Sea Surface Temperature - WHOI, Version 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Ocean Surface Bundle (OSB) Climate Data Record (CDR) consist of three parts: sea surface temperature, near-surface atmospheric properties, and heat fluxes....

  10. A biomarker record of temperature and phytoplankton community in Okinawa Trough since the last glacial maximum

    Science.gov (United States)

    Ruan, Jiaping

    2017-04-01

    A variety of biomarkers were examined from Ocean Drilling Program (ODP) core 1202B to reconstruct temperature and phytoplankton community structures in the southern Okinawa Trough for the past ca. 20000 years. Two molecular temperature proxies (Uk37 and TEX86) show 5-6 ℃ warming during the glacial/interglacial transition. Prior to the Holocene, the Uk37-derived temperature was generally 1-4 ℃ higher than TEX86-derived temperature. This difference, however, was reduced to phytoplankton biomarkers (e.g., C37:2 alkenone, brassicasterol, C30 1,15-diols and dinosterol) suggest a shift of planktonic community assemblages with coccolithophorids becoming more abundant in the Holocene at the expense of diatoms/dinoflagellates. Such a shift is related to the variability of nutrient, temperature and salinity in the Okinawa Trough, controlled by the sea level and the intensity of Kuroshio Current. The phytoplankton community change may have profound implications on atmospheric CO2 fluctuations during glacial/interglacial cycles since diatoms and dinoflagellates have a higher efficiency of biological pump than coccolithophorids.

  11. High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution.

    Science.gov (United States)

    Lecavalier, Benoit S; Fisher, David A; Milne, Glenn A; Vinther, Bo M; Tarasov, Lev; Huybrechts, Philippe; Lacelle, Denis; Main, Brittany; Zheng, James; Bourgeois, Jocelyne; Dyke, Arthur S

    2017-06-06

    We present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ∼12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4-5 °C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ∼3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800-7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ∼1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ∼25% increase in total Greenland ice sheet mass loss (∼1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.

  12. SINOMA - a better tool for proxy based reconstructions?

    Science.gov (United States)

    Buras, Allan; Thees, Barnim; Czymzik, Markus; Dräger, Nadine; Kienel, Ulrike; Neugebauer, Ina; Ott, Florian; Scharnweber, Tobias; Simard, Sonia; Slowinski, Michal; Slowinski, Sandra; Tecklenburg, Christina; Zawiska, Izabela; Wilmking, Martin

    2014-05-01

    Our knowledge on past environmental conditions largely relies on reconstructions that are based on linear regressions between proxy variables (e.g. tree-rings, lake sediments, ice cores) covering a comparably long period (centuries to millennia) and environmental parameters (e.g. climate data) of which only rather short measurement series exist (mostly decades). In general, the corresponding measurements are prone to errors. For instance, air temperature records that are to be prolonged by reconstruction from tree-rings are normally not measured in situ, i.e. where the trees used for reconstructions are growing. In contrast, the variation of tree-ring properties which are used as proxies does not only depend on temperature variations but also on other environmental variables and biological effects. However, if regressions are based on noisy data, knowledge on the noise intensity of both predictor and predictand is needed and model parameter estimates (slope and intercept) will be erroneous if information on the noise is not included in their estimation (Kutzbach et al., 2011). Here, we investigate the performance of the new Sequential Iterative Noise Matching Algorithm (SINOMA; Thees et al., 2009; and Thees et al., submitted) on a variety of typical proxy-data of differing temporal resolution (i.e. hourly (dendrometers, piezometers), seasonally (tree-rings), and annually (tree rings and varved lake sediments)). For each of the investigated proxies a number of pseudo-proxy datasets is generated. I.e. to each proxy variable two different noises are added, resulting in two noisy variables that originate from a common signal (the proxy) and of which the respective error noises and the true model parameters (slope and intercept) between both are known. SINOMA is applied to each of these pseudo-proxy datasets and its performance is evaluated against traditional regression techniques. The herewith submitted contribution thus focuses on the applicability of SINOMA rather

  13. Multi-proxy sedimentary record from Lake Ghirla (N-Italy) reveals hydro-climatic variations and periods of anthropogenic activities during the past 13 kyrs

    Science.gov (United States)

    Wirth, Stefanie B.; Gilli, Adrian; Sessions, Alex L.

    2016-04-01

    Lake Ghirla is a small lake that lies in the southern foothills of the Central Alps near the Swiss-Italian border. Climatically, the region is influenced by North Atlantic and Mediterranean weather systems and is frequently affected by severe storm tracks causing heavy precipitation. The catchment with Permian granites and gneisses contains Pb in amounts significant for mining as well as less important concentrations of Cu, As and U. This sensitive setting makes Lake Ghirla a promising site to reconstruct hydro-climatic variations and to track human activity by means of elevated heavy metal concentrations in the lake sediments. The recovered sediment core comprises the entire Younger Dryas-Holocene time period and was analyzed for (i) sedimentological changes to identify flood deposits, for (ii) the hydrogen isotopic composition of terrestrial plant waxes (plant-wax D/H) to constrain hydro-climatic changes, and for (iii) variations of the elemental composition (XRF core scanning, ICP-MS) to understand anthropogenic impacts. During the past 13 kyrs, we observe a high variability of floods with peak periods appearing at ~11, 10.6-8.2, 6-4.9, 2.8-2.7, 2.6-2.4, 1.2-1 and 0.4-0.1 (LIA) cal kyr BP. From a hydro-climatic perspective, the most remarkable result from the plant-wax D/H data is that the Younger Dryas is characterized by no significant change and that the 2.8-2.7 kyr BP and LIA intervals show an increase of plant-wax D/H values. Hence, during these three cool climatic periods temperature effects cannot be solely responsible for plant-wax D/H variation. The southward migration of the westerly storm tracks above the North Atlantic due to climate cooling must have led to a more southern and thus isotopically enriched moisture source for the southern Alps. This moisture-source change likely counter-balanced or even over-rode the temperature-driven isotope effect. Increased sedimentary Cu concentrations at 3.8-3.3 kyr BP are the first evidence for the presence of

  14. Variations in the width of the Indo-Pacific tropical rain belt over the last millennium: synthesis of stalagmite proxy records and climate model simulations

    Science.gov (United States)

    Ummenhofer, Caroline; Denniston, Rhawn

    2017-04-01

    The seasonal north-south migration of the intertropical convergence zone defines the tropical rain belt (TRB), a region of enormous terrestrial biodiversity and home to 40% of the world's population. The TRB is dynamic and has been shown to shift south as a coherent system during periods of Northern Hemisphere cooling. However, recent studies of Indo-Pacific hydroclimate suggest that during the Little Ice Age (AD 1400-1850), the TRB in this region contracted rather than being displaced uniformly southward. This behaviour is not well understood, particularly during climatic fluctuations less pronounced than those of the Little Ice Age, the largest centennial-scale cool period of the last millennium. Using state-of-the-art climate model simulations conducted as part of the Last Millennium Ensemble with the Community Earth System Model (CESM), we evaluate variations in the width of the Indo-Pacific TRB, as well as movements in the position of its northward and southward edges, across a range of timescales over the pre-Industrial portion of the last millennium (AD 850-1850). The climate model results complement a recent reconstruction of late Holocene variability of the Indo-Pacific TRB, based on a precisely-dated, monsoon-sensitive stalagmite reconstruction from northern Australia (cave KNI-51), located at the southern edge of the TRB and thus highly sensitive to variations at its southern edge. Integrating KNI-51 with a record from Dongge Cave in southern China allows a stalagmite-based TRB reconstruction. Our results reveal that rather than shifting meridionally, the Indo-Pacific TRB expanded and contracted over multidecadal/centennial time scales during the late Holocene, with symmetric weakening/strengthening of summer monsoons in the Northern and Southern Hemispheres of the Indo-Pacific (the East Asian summer monsoon in China and the Australian summer monsoon in northern Australia). Links to large-scale climatic conditions across the Indo-Pacific region

  15. A multi-proxy approach to tracing a regressive event at Ferguson's Gulf, Lake Turkana, Kenya: Implications for modern analogues to assist in interpretations of the Plio-Pleistocene record

    Science.gov (United States)

    Beck, Catherine; Feibel, Craig; Wright, James; Mortlock, Richard

    2014-05-01

    Located in the East African Rift Valley, the Turkana Basin has long been central to our understanding of how early hominins evolved. In particular, there is great curiosity as to the relationship between the paleoenvironment/paleoclimate conditions and evolution. Historical records aid in the interpretation of Plio-Pleistocene sediments by creating the opportunity to ground truth assumptions through the use of modern analogues. This project uses high-resolution, multi-proxy records from a series of short cores spanning the Little Ice Age to the modern, to suggest one possible model for how regressive events are recorded in lacustrine sequences. Because Lake Turkana is hydrologically closed, changes in lake level affect the water chemistry and thereby the ecosystems that depend upon it. Ferguson's Gulf is a 13 km2, shallow embayment located on the western shore of Lake Turkana. The gulf is connected to the rest of the lake by a narrow mouth on its northern end which is ~1 m deep. Therefore, relatively minor drops in lake level have the potential to restrict flow from Lake Turkana into Ferguson's Gulf, creating localized evaporative water chemistry which effects the suitability of this area for sustaining various benthic populations. Six short cores collected in 2011 and 2012 were picked for ostracods at 1-5 cm intervals to study the changes in assemblages and total abundances through time. An age model, generated using radiocarbon dating of ostracods, demonstrated that the record extending into the Little Ice Age (1550-1850 AD), a period when wetter conditions prevailed within the Turkana Basin. The ostracod faunal results were compared with sedimentology/stratigraphy, XRF data, and stable isotope analysis on ostracod shells for a multiproxy approach to reconstructing hydrologic conditions during the past ~500 years. The Ferguson's Gulf record can be subdivided into three bins based on the ostracod assemblages. The lowest third of the core shows high ostracod total

  16. Simultaneous in vivo recording of local brain temperature and electrophysiological signals with a novel neural probe

    Science.gov (United States)

    Fekete, Z.; Csernai, M.; Kocsis, K.; Horváth, Á. C.; Pongrácz, A.; Barthó, P.

    2017-06-01

    Objective. Temperature is an important factor for neural function both in normal and pathological states, nevertheless, simultaneous monitoring of local brain temperature and neuronal activity has not yet been undertaken. Approach. In our work, we propose an implantable, calibrated multimodal biosensor that facilitates the complex investigation of thermal changes in both cortical and deep brain regions, which records multiunit activity of neuronal populations in mice. The fabricated neural probe contains four electrical recording sites and a platinum temperature sensor filament integrated on the same probe shaft within a distance of 30 µm from the closest recording site. The feasibility of the simultaneous functionality is presented in in vivo studies. The probe was tested in the thalamus of anesthetized mice while manipulating the core temperature of the animals. Main results. We obtained multiunit and local field recordings along with measurement of local brain temperature with accuracy of 0.14 °C. Brain temperature generally followed core body temperature, but also showed superimposed fluctuations corresponding to epochs of increased local neural activity. With the application of higher currents, we increased the local temperature by several degrees without observable tissue damage between 34-39 °C. Significance. The proposed multifunctional tool is envisioned to broaden our knowledge on the role of the thermal modulation of neuronal activity in both cortical and deeper brain regions.

  17. Detection of anthropogenic influences on the evolution of temperature records over Europe

    Science.gov (United States)

    Bador, M.; Terray, L.

    2013-12-01

    Extreme events have significant impacts and are among the most serious challenges to society. Here we focus on extreme temperature events, which can cost human lives and affect several sectors (energy, agriculture, water resources, etc), as it happened during the 2003 heat wave in France. One way to study extreme temperature events is the analysis of the occurrence and values of temperature records. By definition, an upper or lower record breaking occurs when a higher or lower value of maximum or minimum surface temperature appears in the annual time series, recorded since an initial date and dependent of the calendar days. This study focuses on the mean upper and lower record occurrence changes over Europe during the 20th and 21st century. In a stationary climate, the occurrence of record breaking temperatures can be expressed by simple probabilistic laws. However, it has been shown using observations that since the beginning of the 1980s the number of record breaking temperature in Europe no longer follows these laws (Wergen and Krug 2010, among others). An increase or decrease in the mean number of upper or lower records is found compared to the stationary climate breaking rate. To understand these changes we use a set of historical (1850-2005) simulations performed with the CNRM-CM5 model. We first use a 10-member ensemble with anthropogenic and natural forcings to calculate the evolution of daily temperature record occurrences. We find the same behavior as in the observations: the upper and lower records diverge from the stationary climate record breaking rate from the 1980's. We then use two other ensembles to attribute these changes to a given set of forcings (either anthropogenic or natural). We show that the simulated record changes from 1980 onwards are mostly due to anthropogenic effects. Using a long (850-year) preindustrial simulation with constant forcings, we also assess these changes with regards to the model internal variability. We then analyze

  18. National Coral Reef Monitoring Program: Water Temperature Data from Subsurface Temperature Recorders (STRs) deployed at coral reef sites in the Pacific Remote Island Areas from 2011 to 2016

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water temperature data are collected using subsurface temperature recorders (STRs) that aid in the monitoring of seawater temperature variability at permanent coral...

  19. National Coral Reef Monitoring Program: Water Temperature Data from Subsurface Temperature Recorders (STRs) deployed at coral reef sites in American Samoa from 2012 to 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water temperature data are collected using subsurface temperature recorders (STRs) that aid in the monitoring of seawater temperature variability at permanent coral...

  20. National Coral Reef Monitoring Program: Water Temperature Data from Subsurface Temperature Recorders (STRs) deployed at coral reef sites in the Hawaiian Archipelago from 2010 to 2016

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water temperature data are collected using subsurface temperature recorders (STRs) that aid in the monitoring of seawater temperature variability at permanent coral...

  1. National Coral Reef Monitoring Program: Water Temperature Data from Subsurface Temperature Recorders (STRs) deployed at coral reef sites in the Marianas Archipelago from 2011 to 2014

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water temperature data are collected using subsurface temperature recorders (STRs) that aid in the monitoring of seawater temperature variability at permanent coral...

  2. Munchausen Syndrome by Proxy: A Family Affair.

    Science.gov (United States)

    Mehl, Albert L.; And Others

    1990-01-01

    The article reports on a case of Munchausen syndrome by proxy in which chronic illicit insulin was administered to a one-year-old child by her mother. Factitious illnesses continued despite psychiatric intervention. Retrospective review of medical records suggested 30 previous episodes of factitious illness within the family. (DB)

  3. Mg/Ca, Sr/Ca, and stable-isotope (δ18O and δ13C) ratio profiles from the fan mussel Pinna nobilis: Seasonal records and temperature relationships

    Science.gov (United States)

    Freitas, Pedro; Clarke, Leon J.; Kennedy, Hilary; Richardson, Christopher; Abrantes, FáTima

    2005-04-01

    We present new annually resolved δ18O, δ13C, Mg/Ca, and Sr/Ca ratio records for two shells of the fast growing Mediterranean fan mussel Pinna nobilis, collected from proximal Spanish coast sea grass meadows. The relationship between the potential geochemical proxies and ontogenetic and environmental controlling factors is investigated. Specifically, the use of shell Mg/Ca and Sr/Ca ratios as potential calcification temperature proxies, the latter calculated from measured shell δ18O values, has been assessed. The δ18O cycles along the growth axis indicate that our P. nobilis specimens are ˜10.5 and ˜4.5 years old. Shell Sr/Ca ratios do not exhibit any consistent interannual cyclicity and are not correlated to temperature. A subtle ontogenetic effect on shell Mg/Ca ratios was observed during the first 4.5 years of recorded growth but was highly evident during the organism's later growth years. In P. nobilis shells, different mechanisms influence ontogenetic variation in shell Mg/Ca and δ18O records. Shell Mg/Ca ratios from the first 4.5 years of growth correlate significantly to temperature, in a best fit relationship described by the equation Mg/Ca = 17.16 ± 1.95 * exp(0.022 ± 0.004 * T). P. nobilis shell Mg/Ca records therefore are a valid temperature proxy only during an early growth phase. For the same range of temperatures, shell Mg/Ca ratios in P. nobilis are approximately 1/3 lower than those reported for inorganic calcite but 3 to 4 times higher than in another bivalve species, Mytilus trossulus, and 4 to 16 times higher than in foraminifera. We suggest these offsets are due to a higher degree of similarity between seawater and calcification-fluid composition in P. nobilis than in other bivalves and foraminifera. The observed shell Mg/Ca ratio change per °C of 2.2% also is lower than that observed for inorganic and other biogenic calcites. Our findings strongly support taxon- and species-specific Mg/Ca-temperature relationships for bivalves and

  4. An early onset of ENSO influence in the extra-tropics of the southwest Pacific inferred from a 14, 600 year high resolution multi-proxy record from Paddy's Lake, northwest Tasmania

    Science.gov (United States)

    Beck, Kristen K.; Fletcher, Michael-Shawn; Gadd, Patricia S.; Heijnis, Henk; Jacobsen, Geraldine E.

    2017-02-01

    Tropical El Niño Southern Oscillation (ENSO) is an important influence on natural systems and cultural change across the Pacific Ocean basin. El Niño events result in negative moisture anomalies in the southwest Pacific and are implicated in droughts and catastrophic wildfires across eastern Australia. An amplification of tropical El Niño activity is reported in the east Pacific after ca. 6.7 ka; however, proxy data for ENSO-driven environmental change in Australia suggest an initial influence only after ca. 5 ka. Here, we reconstruct changes in vegetation, fire activity and catchment dynamics (e.g. erosion) over the last 14.6 ka from part of the southwest Pacific in which ENSO is the main control of interannual hydroclimatic variability: Paddy's Lake, in northwest Tasmania (1065 masl), Australia. Our multi-proxy approach includes analyses of charcoal, pollen, geochemistry and radioactive isotopes. Our results reveal a high sensitivity of the local and regional vegetation to climatic change, with an increase of non-arboreal pollen between ca. 14.6-13.3 ka synchronous with the Antarctic Cold Reversal, and a sensitivity of the local vegetation and fire activity to ENSO variability recorded in the tropical east Pacific through the Holocene. We detect local-scale shifts in vegetation, fire and sediment geochemistry at ca. 6.3, 4.8 and 3.4 ka, simultaneous with increases in El Niño activity in the tropical Pacific. Finally, we observe a fire-driven shift in vegetation from a pyrophobic association dominated by rainforest elements to a pyrogenic association dominated by sclerophyllous taxa following a prolonged (>1 ka) phase of tropical ENSO-amplification and a major local fire event at ca. 3.4 ka. Our results reveal the following key insights: (1) that ENSO has been a persistent modulator of southwest Pacific climate and fire activity through the Holocene; (2) that the climate of northwest Tasmania is sensitive to long-term shifts in tropical ENSO variability; and

  5. A Comparison of Two Air-Temperature Records From Barrow, Alaska, 1976-2004

    Science.gov (United States)

    Klene, A. E.

    2005-12-01

    The National Weather Service (NWS) air temperature record from Barrow, Alaska is one of the most widely used datasets for demonstrating Arctic warming. Yet, recent evidence suggests that there is a substantial heat island in the village (Hinkel et al., 2003; 2004). NWS records in downtown and the National Oceanic and Atmospheric Administration's Climate Monitoring and Diagnostics Lab (CMDL) data from several miles upwind of the village show a distinct difference between urban and rural temperatures. To demonstrate evidence of either a heat island or climate warming, a number of factors must first be examined at each of these sites. These factors are similar to those at most climate-monitoring sites in less remote parts of the world. In the 25 years since the beginning of the CMDL record, Barrow has grown from 2200 to 4600 residents. Instrumentation changes were implemented at both sites. A station move took place. Coastal influences are also large near Barrow and distance from the coast may be an influence. Unraveling the impacts of these considerations on the temperature differences between the NWS and CMDL sites is challenging. While Arctic climate change is a pressing issue and few temperature records are available, care must be taken to ensure that unbiased data are used in analysis. As urban development increases in Arctic regions, information on urban-rural temperature interactions may become more vital, particularly given the possibility of increasing temperatures accompanying climate change.

  6. Proxy Smart Card Systems

    OpenAIRE

    Cattaneo, Giuseppe; Faruolo, Pompeo; Palazzo, Vincenzo; Visconti, Ivan

    2010-01-01

    International audience; The established legal value of digital signatures and the growing availability of identity-based digital services are progressively extending the use of smart cards to all citizens, opening new challenging scenarios. Among them, motivated by concrete applications, secure and practical delegation of digital signatures is becoming more and more critical. Unfortunately, secure delegation systems proposed so far (e.g., proxy signatures) include various drawbacks for any pr...

  7. A novel salinity proxy based on Na incorporation into foraminiferal calcite

    NARCIS (Netherlands)

    Wit, J.C.; de Nooijer, L.J.; Wolthers, M.; Reichart, G.J.

    2013-01-01

    Salinity and temperature determine seawater density, and differences in both thereby control global thermohaline circulation. Whereas numerous proxies have been calibrated and applied to reconstruct temperature, a direct and independent proxy for salinity is still missing. Ideally, a new proxy for

  8. An experimental 392-year documentary-based multi-proxy (vine and grain) reconstruction of May-July temperatures for Kőszeg, West-Hungary

    Science.gov (United States)

    Kiss, Andrea; Wilson, Rob; Bariska, István

    2011-07-01

    In this paper, we present a 392-year-long preliminary temperature reconstruction for western Hungary. The reconstructed series is based on five vine- and grain-related historical phenological series from the town of Kőszeg. We apply dendrochronological methods for both signal assessment of the phenological series and the resultant temperature reconstruction. As a proof of concept, the present reconstruction explains 57% of the temperature variance of May-July Budapest mean temperatures and is well verified with coefficient of efficiency values in excess of 0.45. The developed temperature reconstruction portrays warm conditions during the late seventeenth and early eighteenth centuries with a period of cooling until the coldest reconstructed period centred around 1815, which was followed by a period of warming until the 1860s. The phenological evidence analysed here represent an important data source from which non-biased estimates of past climate can be derived that may provide information at all possible time-scales.

  9. Evidence for higher-than-average air temperatures after the 8.2 ka event provided by a Central European δ18O record

    Science.gov (United States)

    Andersen, Nils; Lauterbach, Stefan; Erlenkeuser, Helmut; Danielopol, Dan L.; Namiotko, Tadeusz; Hüls, Matthias; Belmecheri, Soumaya; Dulski, Peter; Nantke, Carla; Meyer, Hanno; Chapligin, Bernhard; von Grafenstein, Ulrich; Brauer, Achim

    2017-09-01

    The so-called 8.2 ka event represents one of the most prominent cold climate anomalies during the Holocene warm period. Accordingly, several studies have addressed its trigger mechanisms, absolute dating and regional characteristics so far. However, knowledge about subsequent climate recovery is still limited although this might be essential for the understanding of rapid climatic changes. Here we present a new sub-decadally resolved and precisely dated oxygen isotope (δ18O) record for the interval between 7.7 and 8.7 ka BP (103 calendar years before AD 1950), derived from the calcareous valves of benthic ostracods preserved in the varved lake sediments of pre-Alpine Mondsee (Austria). Besides a clear reflection of the 8.2 ka event, showing a good agreement in timing, duration and magnitude with other regional stable isotope records, the high-resolution Mondsee lake sediment record provides evidence for a 75-year-long interval of higher-than-average δ18O values directly after the 8.2 ka event, possibly reflecting increased air temperatures in Central Europe. This observation is consistent with evidence from other proxy records in the North Atlantic realm, thus most probably reflecting a hemispheric-scale climate signal rather than a local phenomenon. As a possible trigger we suggest an enhanced resumption of the Atlantic meridional overturning circulation (AMOC), supporting assumptions from climate model simulations.

  10. Graphical Interface for Measuring and Recording Temperature with the DS18B20 Digital Output Sensor

    OpenAIRE

    Viorel POPA; Elena POPA

    2013-01-01

    The article presents the authors’ two originalgraphical interfaces made in Borland Delphi anddesigned to measure and record (with the DS18B20sensor) a wide range of negative and positivetemperatures. The first interface allows the readingof a sensor’s unique code and then themeasurement and recording of temperature. Thesecond interface can work with a variable numberof such sensors once their unique code has beenentered.The interfaces have been conceived for thestudy of the slow variations of...

  11. Cooperative Proxy Caching for Wireless Base Stations

    Directory of Open Access Journals (Sweden)

    James Z. Wang

    2007-01-01

    Full Text Available This paper proposes a mobile cache model to facilitate the cooperative proxy caching in wireless base stations. This mobile cache model uses a network cache line to record the caching state information about a web document for effective data search and cache space management. Based on the proposed mobile cache model, a P2P cooperative proxy caching scheme is proposed to use a self-configured and self-managed virtual proxy graph (VPG, independent of the underlying wireless network structure and adaptive to the network and geographic environment changes, to achieve efficient data search, data cache and date replication. Based on demand, the aggregate effect of data caching, searching and replicating actions by individual proxy servers automatically migrates the cached web documents closer to the interested clients. In addition, a cache line migration (CLM strategy is proposed to flow and replicate the heads of network cache lines of web documents associated with a moving mobile host to the new base station during the mobile host handoff. These replicated cache line heads provide direct links to the cached web documents accessed by the moving mobile hosts in the previous base station, thus improving the mobile web caching performance. Performance studies have shown that the proposed P2P cooperative proxy caching schemes significantly outperform existing caching schemes.

  12. Oak tree ring stable isotope records of late-summer and autumn temperature changes in the Eastern European lowlands

    Science.gov (United States)

    Nagavciuc, Viorica; Persoiu, Aurel; McCarroll, Danny; Loader, Neil J.; Popa, Ionel

    2017-04-01

    Stable isotopes in tree rings are arguably the best proxies of past climate variability on annual time scales. They can be calibrated against instrumental data and used to extend climate reconstructions for centuries and even millennia. Although records with similar resolution and longer time spans have been recovered in different parts of the world - ice cores in Greenland and varved sediments in lakes in Northern and Western Europe - no such archives exist in Eastern Europe. Therefore, the isotopic composition of tree rings may be the only long-term and high resolution proxy available from this region. Here we present the first results of oxygen and carbon stable isotopes analyses of Quercus robur tree rings, covering the 1900-2016 period. The samples were collected at a low altitude (200m), site in NW Romania (Nușfalău, 47.198277 N, 22.668441 E). We have studied these data in connection with the oxygen isotopic composition of precipitation and the main climatic parameters to evaluate their potential for paleoclimatic reconstructions. Oxygen and carbon stable isotopes composition from earlywood and latewood were analysed separately, from nine pooled Quercus robur trees, using a high-temperature pyrolysis system (Flash HT) coupled to an isotope ratio mass spectrometer (Thermo Delta V), after whole-ring samples were prepared to alpha-cellulose by the modified Jayme-Wise method, and measured tree ring width for the same cores, using LINTAB equipment and TSAP software, with a precision of 0.01mm. Also, we analysed oxygen isotopic composition at Baia Mare station (BM), located at 85km distance from Nușfalău. Climate-measurement parameters relationships were analysed using daily (0.5°x0.5° ROCADA) and monthly (0.5°x0.5° CRU) climatic gridded database. The oxygen isotopic composition of precipitation at BM (average for the 2012-2015 period) has a seasonal variation, with maximum in July (-5.6‰) and minimum in December (-12.8‰). The mean stable isotope

  13. Statistical framework for evaluation of climate model simulations by use of climate proxy data from the last millennium – Part 1: Theory

    Directory of Open Access Journals (Sweden)

    R. Sundberg

    2012-08-01

    Full Text Available A statistical framework for comparing the output of ensemble simulations from global climate models with networks of climate proxy and instrumental records has been developed, focusing on near-surface temperatures for the last millennium. This framework includes the formulation of a joint statistical model for proxy data, instrumental data and simulation data, which is used to optimize a quadratic distance measure for ranking climate model simulations. An essential underlying assumption is that the simulations and the proxy/instrumental series have a shared component of variability that is due to temporal changes in external forcing, such as volcanic aerosol load, solar irradiance or greenhouse gas concentrations. Two statistical tests have been formulated. Firstly, a preliminary test establishes whether a significant temporal correlation exists between instrumental/proxy and simulation data. Secondly, the distance measure is expressed in the form of a test statistic of whether a forced simulation is closer to the instrumental/proxy series than unforced simulations. The proposed framework allows any number of proxy locations to be used jointly, with different seasons, record lengths and statistical precision. The goal is to objectively rank several competing climate model simulations (e.g. with alternative model parameterizations or alternative forcing histories by means of their goodness of fit to the unobservable true past climate variations, as estimated from noisy proxy data and instrumental observations.

  14. Identification of the driving forces of climate change using the longest instrumental temperature record

    OpenAIRE

    Wang, Geli; Yang, Peicai; Zhou, Xiuji

    2017-01-01

    The identification of causal effects is a fundamental problem in climate change research. Here, a new perspective on climate change causality is presented using the central England temperature (CET) dataset, the longest instrumental temperature record, and a combination of slow feature analysis and wavelet analysis. The driving forces of climate change were investigated and the results showed two independent degrees of freedom ?a 3.36-year cycle and a 22.6-year cycle, which seem to be connect...

  15. Munchausen syndrome by proxy

    Directory of Open Access Journals (Sweden)

    Jovanović Aleksandar A.

    2005-01-01

    Full Text Available This review deals with bibliography on Munchausen syndrome by proxy (MSbP. The name of this disorder was introduced by English psychiatrist Roy Meadow who pointed to diagnostic difficulties as well as to serious medical and legal connotations of MSbP. MSbP was classified in DSM-IV among criteria sets provided for further study as "factitious disorder by proxy", while in ICD-10, though not explicitly cited, MSbP might be classified as "factitious disorders" F68.1. MSbP is a special form of abuse where the perpetrator induces somatic or mental symptoms of illness in the victim under his/her care and then persistently presents the victims for medical examinations and care. The victim is usually a preschool child and the perpetrator is the child's mother. Motivation for such pathological behavior of perpetrator is considered to be unconscious need to assume sick role by proxy while external incentives such as economic gain are absent. Conceptualization of MSbP development is still in the domain of psychodynamic speculation, its course is chronic and the prognosis is poor considering lack of consistent, efficient and specific treatment. The authors also present the case report of thirty-three year-old mother who had been abusing her nine year-old son both emotionally and physically over the last several years forcing him to, together with her, report to the police, medical and educational institutions that he had been the victim of rape, poisoning and beating by various individuals, especially teaching and medical staff. Mother manifested psychosis and her child presented with impaired cognitive development, emotional problems and conduct disorder.

  16. Online Junction Temperature Cycle Recording of an IGBT Power Module in a Hybrid Car

    Directory of Open Access Journals (Sweden)

    Marco Denk

    2015-01-01

    Full Text Available The accuracy of the lifetime calculation approach of IGBT power modules used in hybrid-electric powertrains suffers greatly from the inaccurate knowledge of application typical load-profiles. To verify the theoretical load-profiles with data from the field this paper presents a concept to record all junction temperature cycles of an IGBT power module during its operation in a test vehicle. For this purpose the IGBT junction temperature is measured with a modified gate driver that determines the temperature sensitive IGBT internal gate resistor by superimposing the negative gate voltage with a high-frequency identification signal. An integrated control unit manages the TJ measurement during the regular switching operation, the exchange of data with the system controller, and the automatic calibration of the sensor system. To calculate and store temperature cycles on a microcontroller an online Rainflow counting algorithm was developed. The special feature of this algorithm is a very accurate extraction of lifetime relevant information with a significantly reduced calculation and storage effort. Until now the recording concept could be realized and tested within a laboratory voltage source inverter. Currently the IGBT driver with integrated junction temperature measurement and the online cycle recording algorithm is integrated in the voltage source inverter of first test vehicles. Such research will provide representative load-profiles to verify and optimize the theoretical load-profiles used in today’s lifetime calculation.

  17. Consideration of soil types for the calibration of molecular proxies for soil pH and temperature using global soil datasets and Vietnamese soil profiles

    OpenAIRE

    Davtian, N.; Ménot, G.; Bard, E.; Poulenard, J.; Podwojewski, Pascal

    2016-01-01

    Distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in soils depends on environmental parameters such as mean annual air temperature (MAAT) and soil pH. MBT'/MBT'5ME (methylation index of branched tetraethers) and CBT/CBT' (cyclization ratio of branched tetraethers) are ratios based on the relative abundances of brGDGTs. Using these ratios, global and regional/local calibrations have been established using surface soils, but generally without any preliminary study of soil...

  18. Long-Term Instrumental and Reconstructed Temperature Records Contradict Anthropogenic Global Warming

    CERN Document Server

    Lüdecke, Horst-Joachim

    2011-01-01

    Monthly instrumental temperature records from 5 stations in the northern hemisphere are analyzed, each of which is local and over 200 years in length, as well as two reconstructed long-range yearly records - from a stalagmite and from tree rings that are about 2000 years long. In the instrumental records, the steepest 100-year temperature fall happened in the 19th century and the steepest rise in the 20th century, both events being of about the same magnitude. Evaluation by the detrended fluctuation analysis (DFA) yields Hurst exponents that are in good agreement with the literature. DFA, Monte Carlo simulations, and synthetic records reveal that both 100-year events were caused by external trends. In contrast to this, the reconstructed records show stronger 100-year rises and falls as quite common during the last 2000 years. These results contradict the hypothesis of an unusual (anthropogenic) global warming during the 20th century. As a hypothesis, the sun's magnetic field, which is correlated with sunspot ...

  19. [Munchausen by proxy syndrome].

    Science.gov (United States)

    Depauw, A; Loas, G; Delhaye, M

    2015-01-01

    The Munchausen syndrome by proxy (MSBP) was first described in 1977 by the English paediatrician Roy Meadow. The MSBP is an extremely complicated diagnosis because of the difficulty in finding the incriminating evidence of its existence and because of the ethical issue it raises for caregivers. Its implications from a medical, psychological and legal point of view raise difficult questions for any professional confronted to it. In this article we will first present the case of a 16-year-old teenager who had been bedridden in hospital for a year, before an atypical form of MSBP was finally diagnosed, after a stay in a child and adolescent psychiatry unit. We will then discuss this case in light of a literature review on the MSBP.

  20. Identification of the driving forces of climate change using the longest instrumental temperature record

    Science.gov (United States)

    Wang, Geli; Yang, Peicai; Zhou, Xiuji

    2017-04-01

    The identification of causal effects is a fundamental problem in climate change research. Here, a new perspective on climate change causality is presented using the central England temperature (CET) dataset, the longest instrumental temperature record, and a combination of slow feature analysis and wavelet analysis. The driving forces of climate change were investigated and the results showed two independent degrees of freedom —a 3.36-year cycle and a 22.6-year cycle, which seem to be connected to the El Niño-Southern Oscillation cycle and the Hale sunspot cycle, respectively. Moreover, these driving forces were modulated in amplitude by signals with millennial timescales.

  1. Climate variability in the SW Indian Ocean from an 8000-yr long multi-proxy record in the Mauritian lowlands shows a middle to late Holocene shift from negative IOD-state to ENSO-state

    NARCIS (Netherlands)

    De Boer, Erik J.; Tjallingii, Rik; Vélez, Maria I.; Rijsdijk, Kenneth F.; Vlug, Anouk; Reichart, Gert-Jan; Prendergast, Amy L.; de Louw, Perry G B; Florens, F. B Vincent; Baider, Cláudia; Hooghiemstra, Henry

    2014-01-01

    A multi-proxy reconstruction of a sediment core from the Tatos basin in the Mauritian lowlands reveals a dynamic environmental history during the last 8000 years. Under influence of sea level rise, the basin progressed from a wetland to a shallow lake between 8000 and 2500cal yr BP and it slowly

  2. Sea Surface Temperature Climate Data Record for the North Sea and Baltic Sea

    DEFF Research Database (Denmark)

    Høyer, Jacob L.; Karagali, Ioanna

    2016-01-01

    A 30-yr climate data record (CDR) of sea surface temperature (SST) has been produced with daily gap-free analysis fields for the North Sea and the Baltic Sea region from 1982 to 2012 by combining the Pathfinder AVHRR satellite data record with the Along-Track Scanning Radiometer (ATSR) Reprocessing...... observations on average. Validation against independent in situ observations shows a very stable performance of the data record, with a mean difference of -0.06 °C compared to moored buoys and a 0.46 °C standard deviation of the differences. The mean annual biases of the SST CDR are small for all years......, with a negligible temporal trend when compared against drifting and moored buoys. Analysis of the SST CDR reveals that the monthly anomalies for the North Sea, the Danish straits, and the central Baltic Sea regions show a high degree of correlation for interannual and decadal time scales, whereas the monthly...

  3. Proxy consent: moral authority misconceived.

    Science.gov (United States)

    Wrigley, A

    2007-09-01

    The Mental Capacity Act 2005 has provided unified scope in the British medical system for proxy consent with regard to medical decisions, in the form of a lasting power of attorney. While the intentions are to increase the autonomous decision making powers of those unable to consent, the author of this paper argues that the whole notion of proxy consent collapses into a paternalistic judgement regarding the other person's best interests and that the new legislation introduces only an advisor, not a proxy with the moral authority to make treatment decisions on behalf of another. The criticism is threefold. First, there is good empirical evidence that people are poor proxy decision makers as regards accurately representing other people's desires and wishes, and this is therefore a pragmatically inadequate method of gaining consent. Second, philosophical theory explaining how we represent other people's thought processes indicates that we are unlikely ever to achieve accurate simulations of others' wishes in making a proxy decision. Third, even if we could accurately simulate other people's beliefs and wishes, the current construction of proxy consent in the Mental Capacity Act means that it has no significant ethical authority to match that of autonomous decision making. Instead, it is governed by a professional, paternalistic, best-interests judgement that undermines the intended role of a proxy decision maker. The author argues in favour of clearly adopting the paternalistic best-interests option and viewing the proxy as solely an advisor to the professional medical team in helping make best-interests judgements.

  4. Private Computing with Untrustworthy Proxies

    NARCIS (Netherlands)

    Gedrojc, B.

    2011-01-01

    The objective of this thesis is to preserve privacy for the user while untrustworthy proxies are involved in the communication and computation i.e. private computing. A basic example of private computing is an access control system (proxy) which grants access (or not) to users based on fingerprints.

  5. Numerical Modelling of Speleothem and Dripwater Chemistry: Interpreting Coupled Trace Element and Isotope Proxies for Climate Reconstructions

    Science.gov (United States)

    Owen, R.; Day, C. C.; Henderson, G. M.

    2016-12-01

    Speleothem palaeoclimate records are widely used but are often difficult to interpret due to the geochemical complexity of the soil-karst-cave system. Commonly analysed proxies (e.g. δ18O, δ13C and Mg/Ca) may be affected by multiple processes along the water flow path from atmospheric moisture source through to the cave drip site. Controls on speleothem chemistry include rainfall and aerosol chemistry, bedrock chemistry, temperature, soil pCO2, the degree of open-system dissolution and prior calcite precipitation. Disentangling the effects of these controls is necessary to fully interpret speleothem palaeoclimate records. To quantify the effects of these processes, we have developed an isotope-enabled numerical model based on the geochemical modelling software PHREEQC. The model calculates dripwater chemistry and isotopes through equilibrium bedrock dissolution and subsequent iterative CO2 degassing and calcite precipitation. This approach allows forward modelling of dripwater and speleothem proxies, both chemical (e.g. Ca concentration, pH, Mg/Ca and Sr/Ca ratios) and isotopic (e.g. δ18O, δ13C, δ44Ca and radiocarbon content), in a unified framework. Potential applications of this model are varied and the model may be readily expanded to include new isotope systems or processes. Here we focus on calculated proxy co-variation due to changes in model parameters. Examples include: - The increase in Ca concentration, decrease in δ13C and increase in radiocarbon content as bedrock dissolution becomes more open-system. - Covariation between δ13C, δ44Ca and trace metal proxies (e.g. Mg/Ca) predicted by changing prior calcite precipitation. - The effect of temperature change on all proxies through the soil-karst-cave system. Separating the impact of soil and karst processes on geochemical proxies allows more quantitative reconstruction of the past environment, and greater understanding in modern cave monitoring studies.

  6. A History of Warming Sea Surface Temperature and Ocean Acidification Recorded by Planktonic Foraminifera Geochemistry from the Santa Barbara Basin, California

    Science.gov (United States)

    Osborne, E.; Thunell, R.; Bizimis, M.; Buckley, W. P., Jr.; benitez-Nelson, C. R.; Chartier, C. J.

    2015-12-01

    The geochemistry of foraminiferal shells has been widely used to reconstruct past conditions of the ocean and climate. Since the onset of the Industrial Revolution, anthropogenically produced CO2 has resulted in an increase in global temperatures and a decline in the mean pH of the world's oceans. The California Current System is a particularly susceptible region to ocean acidification due to natural upwelling processes that also cause a reduction in seawater pH. The trace element concentration of magnesium and boron in planktonic foraminiferal shells are used here as proxies for temperature and carbonate ion concentration ([CO32-]), respectively. Newly developed calibrations relating Mg/Ca ratios to temperature (R2 0.91) and B/Ca ratios to [CO32-] (R2 0.84) for the surface-mixed layer species Globogerina bulloides were generated using material collected in the Santa Barbara Basin sediment trap time-series. Using these empirical relationships, temperature and [CO32-] are reconstructed using a 0.5 meter long multi-core collected within the basin. 210Pb activities were used to determine a sedimentation rate for the core to estimate ages for core samples (sedimentation rate: 0.341 cm/yr). A spike in 137Cs activity is used as a tie-point to the year 1965 coinciding with the peak of nuclear bomb testing. Our down-core record extends through the mid-19th century to create a history of rising sea surface temperatures and declining [CO32-] as a result of anthropogenic CO2 emissions.

  7. Technical Note: Correcting for signal attenuation from noisy proxy data in climate reconstructions

    Directory of Open Access Journals (Sweden)

    C. M. Ammann

    2010-04-01

    Full Text Available Regression-based climate reconstructions scale one or more noisy proxy records against a (generally short instrumental data series. Based on that relationship, the indirect information is then used to estimate that particular measure of climate back in time. A well-calibrated proxy record(s, if stationary in its relationship to the target, should faithfully preserve the mean amplitude of the climatic variable. However, it is well established in the statistical literature that traditional regression parameter estimation can lead to substantial amplitude attenuation if the predictors carry significant amounts of noise. This issue is known as "Measurement Error" (Fuller, 1987; Carroll et al., 2006. Climate proxies derived from tree-rings, ice cores, lake sediments, etc., are inherently noisy and thus all regression-based reconstructions could suffer from this problem. Some recent applications attempt to ward off amplitude attenuation, but implementations are often complex (Lee et al., 2008 or require additional information, e.g. from climate models (Hegerl et al., 2006, 2007. Here we explain the cause of the problem and propose an easy, generally applicable, data-driven strategy to effectively correct for attenuation (Fuller, 1987; Carroll et al., 2006, even at annual resolution. The impact is illustrated in the context of a Northern Hemisphere mean temperature reconstruction. An inescapable trade-off for achieving an unbiased reconstruction is an increase in variance, but for many climate applications the change in mean is a core interest.

  8. Technical Note: Correcting for signal attenuation from noisy proxy data in climate reconstructions

    KAUST Repository

    Ammann, C. M.

    2010-04-20

    Regression-based climate reconstructions scale one or more noisy proxy records against a (generally) short instrumental data series. Based on that relationship, the indirect information is then used to estimate that particular measure of climate back in time. A well-calibrated proxy record(s), if stationary in its relationship to the target, should faithfully preserve the mean amplitude of the climatic variable. However, it is well established in the statistical literature that traditional regression parameter estimation can lead to substantial amplitude attenuation if the predictors carry significant amounts of noise. This issue is known as "Measurement Error" (Fuller, 1987; Carroll et al., 2006). Climate proxies derived from tree-rings, ice cores, lake sediments, etc., are inherently noisy and thus all regression-based reconstructions could suffer from this problem. Some recent applications attempt to ward off amplitude attenuation, but implementations are often complex (Lee et al., 2008) or require additional information, e.g. from climate models (Hegerl et al., 2006, 2007). Here we explain the cause of the problem and propose an easy, generally applicable, data-driven strategy to effectively correct for attenuation (Fuller, 1987; Carroll et al., 2006), even at annual resolution. The impact is illustrated in the context of a Northern Hemisphere mean temperature reconstruction. An inescapable trade-off for achieving an unbiased reconstruction is an increase in variance, but for many climate applications the change in mean is a core interest.

  9. Future summer mega-heatwave and record-breaking temperatures in a warmer France climate

    Science.gov (United States)

    Bador, Margot; Terray, Laurent; Boé, Julien; Somot, Samuel; Alias, Antoinette; Gibelin, Anne-Laure; Dubuisson, Brigitte

    2017-07-01

    This study focuses on future very hot summers associated with severe heatwaves and record-breaking temperatures in France. Daily temperature observations and a pair of historical and scenario (greenhouse gas radiative concentration pathway 8.5) simulations with the high-resolution (∼12.5 km) ALADIN regional climate model provide a robust framework to examine the spatial distribution of these extreme events and their 21st century evolution. Five regions are identified with an extreme event spatial clustering algorithm applied to observed temperatures. They are used to diagnose the 21st century heatwave spatial patterns. In the 2070s, we find a simulated mega-heatwave as severe as the 2003 observed heatwave relative to its contemporaneous climate. A 20-member initial condition ensemble is used to assess the sensitivity of this future heatwave to the internal variability in the regional climate model and to pre-existing land surface conditions. Even in a much warmer and drier climate in France, late spring dry land conditions may lead to a significant amplification of summer extreme temperatures and heatwave intensity through limitations in evapotranspiration. By 2100, the increase in summer temperature maxima exhibits a range from 6 °C to almost 13 °C in the five regions in France, relative to historical maxima. These projections are comparable with the estimates given by a large number of global climate models.

  10. An Inter-calibrated Passive Microwave Brightness Temperature Data Record and Ocean Products

    Science.gov (United States)

    Hilburn, K. A.; Wentz, F. J.

    2014-12-01

    Inter-calibration of passive microwave sensors has been the subject of on-going activity at Remote Sensing Systems (RSS) since 1974. RSS has produced a brightness temperature TB data record that spans the last 28 years (1987-2014) from inter-calibrated passive microwave sensors on 14 satellites: AMSR-E, AMSR2, GMI, SSMI F08-F15, SSMIS F16-F18, TMI, WindSat. Accompanying the TB record are a suite of ocean products derived from the TBs that provide a 28-year record of wind speed, water vapor, cloud liquid, and rain rate; and 18 years (1997-2014) of sea surface temperatures, corresponding to the period for which 6 and/or 10 GHz measurements are available. Crucial to the inter-calibration and ocean product retrieval are a highly accurate radiative transfer model RTM. The RSS RTM has been continually refined for over 30 years and is arguably the most accurate model in the 1-100 GHz spectrum. The current generation of TB and ocean products, produced using the latest version of the RTM, is called Version-7. The accuracy of the Version-7 inter-calibration is estimated to be 0.1 K, based on inter-satellite comparisons and validation of the ocean products against in situ measurements. The data record produced by RSS has had a significant scientific impact. Over just the last 14 years (2000-2013) RSS data have been used in 743 peer-reviewed journal articles. This is an average of 4.5 peer-reviewed papers published every month made possible with RSS data. Some of the most important scientific contributions made by RSS data have been to the study of the climate. The AR5 Report "Climate Change 2013: The Physical Science Basis" by the Intergovernmental Panel on Climate Change (IPCC), the internationally accepted authority on climate change, references 20 peer-reviewed journal papers from RSS scientists. The report makes direct use of RSS water vapor data, RSS atmospheric temperatures from MSU/AMSU, and 9 other datasets that are derived from RSS data. The RSS TB data record is

  11. Changes in record-breaking temperature events in China and projections for the future

    Science.gov (United States)

    Deng, Hanqing; Liu, Chun; Lu, Yanyu; He, Dongyan; Tian, Hong

    2017-06-01

    As global warming intensifies, more record-breaking (RB) temperature events are reported in many places around the world where temperatures are higher than ever before http://cn.bing.com/dict/search?q=.&FORM=BDVSP6&mkt=zh-cn. The RB temperatures have caused severe impacts on ecosystems and human society. Here, we address changes in RB temperature events occurring over China in the past (1961-2014) as well as future projections (2006-2100) using observational data and the newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The number of RB events has a significant multi-decadal variability in China, and the intensity expresses a strong decrease from 1961 to 2014. However, more frequent RB events occurred in mid-eastern and northeastern China over last 30 years (1981-2010). Comparisons with observational data indicate multi-model ensemble (MME) simulations from the CMIP5 model perform well in simulating RB events for the historical run period (1961-2005). CMIP5 MME shows a relatively larger uncertainty for the change in intensity. From 2051 to 2100, fewer RB events are projected to occur in most parts of China according to RCP 2.6 scenarios. Over the longer period from 2006 to 2100, a remarkable increase is expected for the entire country according to RCP 8.5 scenarios and the maximum numbers of RB events increase by approximately 600 per year at end of twenty-first century.

  12. Accuracy of recorded body temperature of critically ill patients related to measurement site: a prospective observational study.

    Science.gov (United States)

    Nonose, Y; Sato, Y; Kabayama, H; Arisawa, A; Onodera, M; Imanaka, H; Nishimura, M

    2012-09-01

    Accurate measurement of body temperature is an important indicator of the status of critically ill patients and is therefore essential. While axillary temperature is not considered accurate, it is still the conventional method of measurement in Asian intensive care units. There is uncertainty about the accuracy of thermometers for the critically ill. We compared the accuracy and precision of bladder, axillary and tympanic temperature measurements in critically ill patients. A total of 73 critically ill patients admitted to the intensive care unit of a teaching hospital were prospectively enrolled. Every four hours, we measured body temperature at three sites (bladder, axillary and tympanic). If the patient had received an indwelling pulmonary artery catheter, blood temperature was also recorded and this was compared with bladder, axillary and tympanic temperature readings. For all patients, axillary and tympanic temperature readings were compared with bladder temperature readings. Accuracy and precision were analysed using Bland-Altman analysis. When blood temperature data was available, the mean difference between blood and bladder temperature readings was small (0.02±0.21°C). Compared with bladder temperature, mean difference for axillary temperature was -0.33±0.55°C and for tympanic temperature it was -0.51±1.02°C. For critically ill patients, recorded axillary temperature was closer to bladder temperature than tympanic temperature.

  13. Planktonic foraminiferal rare earth elements as a potential new aeolian dust proxy

    Science.gov (United States)

    Chou, C.; Liu, Y.; Lo, L.; Wei, K.; Shen, C.

    2012-12-01

    Characteristics of rare earth elements (REEs) have widely been used as important tracers in many fields of earth sciences, including lithosphere research, environmental change, ocean circulation and other natural carbonate materials. Foraminiferal test REE signatures have been suggested to reflect ambient seawater conditions and serve as valuable proxies in the fields of paleoceanography and paleoclimate. Here we present a 60-kyr planktonic foraminifera Globigerinoides ruber (white, 250-300 μm) REE record of a sediment core MD05-2925 (9°20.61'S, 151°27.61'E, water depth 1660 m) from the Solomon Sea. The REE diagram shows two dominant sources of local seawater and nearby terrestrial input. The variability of foraminiferal REE/Ca time series is different from Mg/Ca-inferred sea surface temperature and δ18O records during the past 60-kyr. This inconsistency suggests that planktonic foraminiferal REE content cannot result only from changes in ice volume and temperature. Synchroneity between high planktonic foraminiferal REE content and Antarctic ice core dust amount record implies the same dust sources, probably from Australia or mainland China. Our results suggest that foraminiferal REE can potentially be as a new dust proxy and record dry/humid conditions at the source area.

  14. Robotic Vehicle Proxy Simulation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Energid Technologies proposes the development of a digital simulation that can replace robotic vehicles in field studies. This proxy simulation will model the...

  15. An alternative method to record rising temperatures during dental implant site preparation: a preliminary study using bovine bone

    Directory of Open Access Journals (Sweden)

    Domenica Laurito

    2010-12-01

    Full Text Available Overheating is constantly mentioned as a risk factor for bone necrosis that could compromise the dental implant primary stability. Uncontrolled thermal injury can result in a fibrous tissue, interpositioned at the implant-bone interface, compromising the long-term prognosis. The methods used to record temperature rise include either direct recording by thermocouple instruments or indirect estimating by infrared thermography. This preliminary study was carried out using bovine bone and a different method of temperatures rising estimation is presented. Two different types of drills were tested using fluoroptic thermometer and the effectiveness of this alternative temperature recording method was evaluated.

  16. Graphical Interface for Measuring and Recording Temperature with the DS18B20 Digital Output Sensor

    Directory of Open Access Journals (Sweden)

    Viorel POPA

    2013-06-01

    Full Text Available The article presents the authors’ two originalgraphical interfaces made in Borland Delphi anddesigned to measure and record (with the DS18B20sensor a wide range of negative and positivetemperatures. The first interface allows the readingof a sensor’s unique code and then themeasurement and recording of temperature. Thesecond interface can work with a variable numberof such sensors once their unique code has beenentered.The interfaces have been conceived for thestudy of the slow variations of air temperatureinside chambers or wood, in timber freezing,heating or drying processes.To achieve the purpose we have alsoexperimented on other variants of temperaturesensors, but finally we have adopted the variantthat uses the DS18B20 digital output sensormanufactured by Dallas Company. This sensor hasthe following advantages:- a small size (it can be easily inserted into a 4mm diameter hole made in the wood piece;- it measures temperatures between -55°Cand +125°C;- it can relatively easily connect to the RS232serial port of a computer;- with only two wires one can ensure datainsertion and transmission from a numberof 4 ÷ 10 sensors of this type.

  17. Improving age-depth models using sedimentary proxies for accumulation rates in fluvio-lacustrine deposits

    NARCIS (Netherlands)

    Minderhoud, P.S.J.; Cohen, K.M.|info:eu-repo/dai/nl/185633374; Toonen, W.H.J.|info:eu-repo/dai/nl/317725505; Erkens, G.|info:eu-repo/dai/nl/323349382; Hoek, W.Z.|info:eu-repo/dai/nl/163819394

    2017-01-01

    Lacustrine fills, including those of oxbow lakes in river floodplains, often hold valuable sedimentary and biological proxy records of palaeo-environmental change. Precise dating of accumulated sediments at levels throughout these records is crucial for interpretation and correlation of (proxy) data

  18. Changes of coastal upwelling systems in the Atlantic, Indian and Pacific oceans recorded from alkenone-derived sea surface temperatures and other multiproxy information

    Science.gov (United States)

    El Ouahabi, Anuar; Martrat, Belen; Lopez, Jordi F.; Grimalt, Joan O.

    2014-05-01

    Upwelling regions have received limited attention in paleoceanography, particularly for what concerns their changes at high temporal resolution. Furthermore, they have generally been considered independently. The lack of integrated studies of the evolution of the main coastal upwelling systems has limited the present degree of understanding of the links between global ocean dynamics and intensity and geographic distribution of these highly productive sites. In the present study, an integrated assessment of sea surface temperature (SST) records based on literature available alkenone-data on the upwelling regions of North-West Africa, North-West Arabian Sea, Namibia and Peru encompassing the last 25 kyr is reported. Additionally, in order to consider the complex effects of regional processes literature-available multiproxy data (marine, ice cores and speleothems records; PIG2LIG-4FUTURE database; Geophysical Research Abstracts Vol. 14, EGU2012-13825) has also been used to constrain upwelling features. This approach has allowed the description of high resolution temporal and spatial upwelling patterns and the interdependences between ocean dynamics and upwelling shifts. The spatio-temporal SST-upwelling patterns during the deglaciation-Holocene stage have been discussed. Suitable proxies for the upwelling and advection processes, such as CaCO3, TOC and Opal, Nd and carbon isotopes, respectively have been studied. Temporal snapshots at approximately at 22 ka, 15 ka, 12 ka, 8 ka, and 5 ka BP have been identified. These transitions illustrate flips between contrasting states. Major environmental and climatic changes have been observed before and after this type of transition, e.g. the one at 5 ka BP. These observations provide interesting clues on mechanisms, location of forcings and sustainers. The high temporal resolution records examined provide good constraints on the timing and magnitude of oceanic processes related with upwelling change and therefore an assessment

  19. Pathfinder Version 5.3 AVHRR Sea Surface Temperature Climate Data Record

    Science.gov (United States)

    Baker-Yeboah, S.; Kilpatrick, K. A.

    2016-12-01

    Long-term, climate data records of global sea surface temperature (SST) are important for ocean and climate variability studies. The NOAA National Centers for Environmental Information process, maintain, and continue development of the long-term, Pathfinder climate data record of global SST. These SST values are generated at approximately a 4 km resolution using a consistent algorithm for Advanced Very High Resolution Radiometer (AVHRR) instruments aboard NOAA polar-orbiting satellites dating back to 1981. A new version of the Pathfinder SST products, version 5.3, has recently been produced for a thirty three year period (1981 - 2014). This latest reprocessing used an Amazon Web Service cloud system and a modernized version of the heritage Pathfinder SST codes integrated into the open source NASA SeaWiFS Data Analysis System (SeaDAS6.4). Coefficients for this SST product were generated using regression analyses with co-located in situ and satellite measurements. Validation results corresponding to Pathfinder Level 3 skin SST minus sub-surface buoy SST show a global mean difference of -0.2 K with a standard deviation of 0.5 K. New quality control procedures for the new version of Pathfinder SST Climate Data Record products will be presented along with other improvements made in comparison to previous versions of Pathfinder SST.

  20. Validation of the Suomi NPP VIIRS Ice Surface Temperature Environmental Data Record

    Directory of Open Access Journals (Sweden)

    Yinghui Liu

    2015-12-01

    Full Text Available Continuous monitoring of the surface temperature is critical to understanding and forecasting Arctic climate change; as surface temperature integrates changes in the surface energy budget. The sea-ice surface temperature (IST has been measured with optical and thermal infrared sensors for many years. With the IST Environmental Data Record (EDR available from the Visible Infrared Imaging Radiometer Suite (VIIRS onboard the Suomi National Polar-orbiting Partnership (NPP and future Joint Polar Satellite System (JPSS satellites; we can continue to monitor and investigate Arctic climate change. This work examines the quality of the VIIRS IST EDR. Validation is performed through comparisons with multiple datasets; including NASA IceBridge measurements; air temperature from Arctic drifting ice buoys; Moderate Resolution Imaging Spectroradiometer (MODIS IST; MODIS IST simultaneous nadir overpass (SNO; and surface air temperature from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR reanalysis. Results show biases of −0.34; −0.12; 0.16; −3.20; and −3.41 K compared to an aircraft-mounted downward-looking pyrometer; MODIS; MODIS SNO; drifting buoy; and NCEP/NCAR reanalysis; respectively; root-mean-square errors of 0.98; 1.02; 0.95; 4.89; and 6.94 K; and root-mean-square errors with the bias removed of 0.92; 1.01; 0.94; 3.70; and 6.04 K. Based on the IceBridge and MODIS results; the VIIRS IST uncertainty (RMSE meets or exceeds the JPSS system requirement of 1.0 K. The product can therefore be considered useful for meteorological and climatological applications.

  1. A Fundamental Climate Data Record of Intercalibrated Brightness Temperature Data from SSM/I and SSMIS

    Science.gov (United States)

    Sapiano, M. R. P.; Berg, W. K.; McKague, D.; Kummerow, C. D.

    2012-04-01

    The first Special Sensor Microwave/Imager (SSM/I) was launched in June 1987 on the Defense Meteorological Satellite Program's (DMSP) F08 spacecraft and started what is now a nearly continuous 24-year record of passive microwave imager data that can be used to monitor the climate system. This includes such fields as precipitation (over both land and ocean), the extent of sea ice and snow, sea ice concentration, total precipitable water, cloud liquid water, and surface wind speed over oceans. A total of nine window channel radiometers have been launched to date in the DMSP series including the SSM/I instrument on board F08, F10, F11, F13, F14, and F15 followed by the Special Sensor Microwave Imager/Sounder (SSMIS) on board F16, F17, and F18, which is expected to operate for at least the next decade. As a result, this data record provides the best available source of long-term global observations of several hydrological variables for climate applications. Although the DMSP sensors provide a long-term record, because the sensors were developed for operational use there are a number of issues that must be addressed to produce a dataset suitable for use in climate applications. There are a several quality control and calibration issues including, but not limited to, quality control of the original antenna temperatures, geolocation, cross-track bias corrections, solar and lunar intrusion issues and emissive antennas. The goal of producing an FCDR of brightness temperature data involves not only addressing many of these instrument issues, but also developing a well-documented, transparent approach that allows for subsequent improvements as well as a framework for incorporating future sensors. Once the data have been quality controlled and various calibration corrections have been applied, the goal is to adjust the calibration of the various sensors so that they are physically consistent. Such intercalibration does not correct for changes due to local observing time, which

  2. Comparing Sunspot Area and Sunspot Number as Proxies for Long-term Solar Irradiance Variation

    Science.gov (United States)

    Jordan, Stuart D.; Garcia, A. G.; Oegerle, William (Technical Monitor)

    2002-01-01

    Because relevant observations from space began only in 1979 with Nimbus-7, it is impossible to correlate direct measurements of small changes in solar irradiance with terrestrial temperature over a number of solar cycles. Yet there is recent evidence that some feature of solar change over a cycle may have a larger influence on climate than would result from merely introducing the additional amount of heat delivered to Earth's atmosphere at solar minimum. It would be useful to check this possibility over several solar cycles. To do this, we would need a sufficiently reliable proxy for irradiance change that at least survives a test against the space observations. Sunspot area is a fairly straightforward parameter to measure, and is associated with the extent of magnetic activity known to correlate strongly with solar irradiance change. We have tested the use of sunspot area as a long-term proxy for solar irradiance change, using observations made at the Coimbra Solar Observatory, from which we obtain both statistically weighted sunspot numbers and sunspot areas over the period 1980-1992. These are both correlated with solar irradiance values measured from Nimbus-7 spacecraft over the same time period, to see if sunspot area offers affords a strong positive correlation and also a distinct advantage over sunspot number as a useful proxy that can then be compared with terrestrial temperature records. Preliminary results yield a positive correlation of 0.71 for sunspot area, but further tests are being conducted and will be reported.

  3. Little Ice Age versus Present Day: Comparison of Temperature, Precipitation and Seasonality in Speleothem Records from the Han-sur-Lesse Cave, Belgium.

    Science.gov (United States)

    Vansteenberge, S.; Van Opdenbosch, J.; Van Rampelbergh, M.; Verheyden, S.; Keppens, E.; Cheng, H.; Edwards, R. L.; Claeys, P. F.

    2015-12-01

    The Proserpine stalagmite is a 2 m large, tabular-shaped speleothem located in the Han-sur-Lesse cave in Belgium. The speleothem formed over the last 1000 years and is still growing. High-accuracy U/Th datings have indicated exceptionally high growth-rates of up to 2 mm per year. This, together with a well expressed annual layering, makes the Proserpine stalagmite an ideal candidate for high-resolution paleoclimate reconstructions of the last millennium. Previous work, including over 10 years of cave monitoring, has already learned us how short-term, i.e. decadal to seasonal, climate variations are incorporated within speleothem calcite from the Han-sur-Lesse cave system. It has been shown that δ18O and δ13C stable isotopes and trace element proxies of recently formed calcite reflect seasonal variations in temperature and precipitation of the near-cave environment (Verheyden et al, 2008; Van Rampelbergh et al., 2014). Now, this knowledge was used to infer local climate parameters further back in time to the period of +/- 1620-1630 CE, corresponding to one of the cold peaks within the Little Ice Age. Speleothem calcite was sampled at sub-annual resolution, with approximately 11 samples per year, for stable isotope analysis. LA-ICP-MS and µXRF analyses resulted in time series of trace elements. Preliminary results indicate a well expressed seasonal signal in δ13C and trace element composition but a multi-annual to decadal trend in δ18O. This combined proxy study eventually enables comparison of the expression of seasonality and longer term climate variations between a Little Ice Age cold peak and Present Day. References: Verheyden, S. et al., 2008, Monitoring climatological, hydrological and geochemical parameters in the Père Noël cave (Belgium): implication for the interpretation of speleothem isotopic and geochemical time-series. International Journal of Speleology, 37(3), 221-234. Van Rampelbergh, M. et al., 2014, Seasonal variations recorded in cave

  4. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Land Surface Temperature (LST) Environmental Data Record (EDR) from IDPS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) of Land Surface Temperature (LST) from the Visible Infrared Imaging Radiometer Suite...

  5. NOAA Climate Data Record (CDR) of SSM/I and SSMIS Microwave Brightness Temperatures, RSS Version 7

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Version 7 NOAA Fundamental Climate Data Record (CDR) from Remote Sensing Systems (RSS) contains brightness temperatures that have been inter-calibrated and...

  6. NOAA Climate Data Record (CDR) of SSM/I and SSMIS Microwave Brightness Temperatures, CSU Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) from Colorado State University (CSU) contains brightness temperatures that have been improved and quality-controlled over the...

  7. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Ice Concentration and Ice Surface Temperature Environmental Data Records (EDRs) from NDE

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) of Sea Ice Concentration (SIC) and Ice Surface Temperature (IST) from the Visible...

  8. NOAA Climate Data Record (CDR) of Advanced Microwave Sounding Unit (AMSU)-A Brightness Temperature, Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Climate Data Record (CDR) for Advanced Microwave Sounding Unit-A (AMSU-A) brightness temperature in "window channels". The data cover a time period from...

  9. Molecular records of continental air temperature and monsoon precipitation variability in East Asia spanning the past 130,000 years

    NARCIS (Netherlands)

    Peterse, F.|info:eu-repo/dai/nl/371172314; Martínez-García, A.; Zhou, B.; Beets, C.J.; Prins, M.A.; Zheng, H.; Eglinton, T.I.

    2014-01-01

    Our current understanding of past changes in East Asian summer monsoon (EASM) precipitation intensity derives from several loess–paleosol sequences and oxygen isotope (δ18O) records of well-dated stalagmites. Although temperature is generally presumed to have had minimal impact on EASM records, past

  10. A reconstruction of temperature, ice volume and atmospheric CO2 over the past 40 million years

    NARCIS (Netherlands)

    de Boer, B.|info:eu-repo/dai/nl/304023183

    2012-01-01

    Knowledge on past climate change largely emerges from sediment records drilled from the ocean floor and ice-core records from the Antarctic and Greenland ice sheets. From these records proxy data is obtained indicating changes in, for example, temperature, sea level and greenhouse gas

  11. Climate Change: A New Metric to Measure Changes in the Frequency of Extreme Temperatures using Record Data

    Science.gov (United States)

    Munasinghe, L.; Jun, T.; Rind, D. H.

    2012-01-01

    Consensus on global warming is the result of multiple and varying lines of evidence, and one key ramification is the increase in frequency of extreme climate events including record high temperatures. Here we develop a metric- called "record equivalent draws" (RED)-based on record high (low) temperature observations, and show that changes in RED approximate changes in the likelihood of extreme high (low) temperatures. Since we also show that this metric is independent of the specifics of the underlying temperature distributions, RED estimates can be aggregated across different climates to provide a genuinely global assessment of climate change. Using data on monthly average temperatures across the global landmass we find that the frequency of extreme high temperatures increased 10-fold between the first three decades of the last century (1900-1929) and the most recent decade (1999-2008). A more disaggregated analysis shows that the increase in frequency of extreme high temperatures is greater in the tropics than in higher latitudes, a pattern that is not indicated by changes in mean temperature. Our RED estimates also suggest concurrent increases in the frequency of both extreme high and extreme low temperatures during 2002-2008, a period when we observe a plateauing of global mean temperature. Using daily extreme temperature observations, we find that the frequency of extreme high temperatures is greater in the daily minimum temperature time-series compared to the daily maximum temperature time-series. There is no such observable difference in the frequency of extreme low temperatures between the daily minimum and daily maximum.

  12. Testing Novel pH Proxies through Inorganic Calcite Precipitations and K/Pg Foraminifera

    Science.gov (United States)

    Super, J. R.; Pagani, M.; Wang, Z.

    2013-12-01

    Ocean pH proxies help constrain the carbon system in the paleocean and can be used to infer atmospheric CO2 when coupled with estimates of total alkalinity, aqueous pCO2 or dissolved inorganic carbon. This project investigates two novel pH proxies (cerium abundance and kinetically-controlled oxygen isotopes) through a series of precipitations of inorganic calcite, as well as the previously established boron isotope pH proxy. Precipitations are performed using varied pH and carbonate saturation states that span the range of typical ocean values as well as a 'free drift' that allows pH and saturation state to vary. The light rare earth element cerium speciates, depending on local oxidation-reduction conditions, between the soluble Ce3+ and highly insoluble Ce4+ ions, causing a relative depletion of cerium in ocean water. This project demonstrates how a suite rare earth elements, including cerium, partitions into inorganic calcite and how partitioning varies with changing pH and carbonate saturation state. Oxygen isotope fractionation is primarily controlled by temperature, but this project examines how pH and carbonate saturation state correlate with oxygen isotope values under kinetic conditions during the initial stage of precipitation. The effect of diagenesis on each proxy is simulated by dissolution of precipitated calcite in a pressure vessel. Results from the precipitations are used to inform a record of well-preserved benthic and planktonic foraminifera from DSDP Site 356 that range in age from the K/Pg boundary to the period when the δ13C gradient between the surface and deep ocean returned to pre-event levels. The pH record is used to infer the magnitude and length of the perturbation to the oceanic carbon system following the extinction event, particularly in terms of export productivity.

  13. A Multi-Proxy Perspective on Climate Variability in the Tropical Pacific over the Last Millennium

    Science.gov (United States)

    Quinn, Terrence; Partin, Jud; Thirumalai, Kaustubh; Hereid, Kelly; Maupin, Chris; Shen, Chuan-Chou; Taylor, Fred

    2014-05-01

    The southwest Pacific is a major source of tropical climate variability through heat and moisture exchanges associated with the Western Pacific Warm Pool (WPWP) and the South Pacific Convergence Zone (SPCZ). These variations are especially significant at the annual, ENSO, and multi-decadal timescales. Climate proxy records from the tropical Pacific must be used to extend records of SST, SSS, and rainfall variations into the pre-instrumental period. We highlight our recent efforts to quantitatively understand tropical climate variability over the last millennium using numerical simulations and climate proxy records (corals and stalagmites), the latter of which overlap with, and extend beyond the instrumental period. We investigate the use of individual foraminiferal analyses (IFA) in assessing past ENSO variability using numerical simulations. The simulation quantifies the sensitivity of IFA to ENSO amplitude and seasonal cycle amplitude (or a combination of both) at different locations in the tropical Pacific. Results indicate that IFA sensitivity towards ENSO is highest at the central equatorial Pacific surface ocean and the eastern equatorial Pacific (EEP) thermocline, whereas sensitivity towards the seasonal cycle is highest at the EEP surface ocean. We investigate tropical surface ocean variability using two recent coral-based climate reconstructions: a 233 yr record from Misima Island, Papua New Guinea (10.6° S, 152.8° E) and a 293 yr record from Olasana Island, Western Province, Solomon Islands (8.2° S, 157.2° E). The PNG coral record of monthly resolved δ18O and Sr/Ca variations spans the interval ~1414-1645. This record indicates that the surface ocean in this region experienced a small change in hydrologic balance with no change in temperature, extended periods of quiescence in El Niño activity, and no change in average amplitudes of El Niño events relative to signals captured in regional modern records. The Solomon coral δ18O record (1716

  14. Qualitative and Quantitative Sentiment Proxies

    DEFF Research Database (Denmark)

    Zhao, Zeyan; Ahmad, Khurshid

    2015-01-01

    Sentiment analysis is a content-analytic investigative framework for researchers, traders and the general public involved in financial markets. This analysis is based on carefully sourced and elaborately constructed proxies for market sentiment and has emerged as a basis for analysing movements...... and trading volumes. The case study we use is a small market index (Danish Stock Exchange Index, OMXC 20, together with prevailing sentiment in Denmark, to evaluate the impact of sentiment on OMXC 20. Furthermore, we introduce a rather novel and quantitative sentiment proxy, that is the use of the index...

  15. Record-high specific conductance and water temperature in San Francisco Bay during water year 2015

    Science.gov (United States)

    Work, Paul; Downing-Kunz, Maureen; Livsey, Daniel

    2017-02-22

    The San Francisco estuary is commonly defined to include San Francisco Bay (bay) and the adjacent Sacramento–San Joaquin River Delta (delta). The U.S. Geological Survey (USGS) has operated a high-frequency (15-minute sampling interval) water-quality monitoring network in San Francisco Bay since the late 1980s (Buchanan and others, 2014). This network includes 19 stations at which sustained measurements have been made in the bay; currently, 8 stations are in operation (fig. 1). All eight stations are equipped with specific conductance (which can be related to salinity) and water-temperature sensors. Water quality in the bay constantly changes as ocean tides force seawater in and out of the bay, and river inflows—the most significant coming from the delta—vary on time scales ranging from those associated with storms to multiyear droughts. This monitoring network was designed to observe and characterize some of these changes in the bay across space and over time. The data demonstrate a high degree of variability in both specific conductance and temperature at time scales from tidal to annual and also reveal longer-term changes that are likely to influence overall environmental health in the bay.In water year (WY) 2015 (October 1, 2014, through September 30, 2015), as in the preceding water year (Downing-Kunz and others, 2015), the high-frequency measurements revealed record-high values of specific conductance and water temperature at several stations during a period of reduced freshwater inflow from the delta and other tributaries because of persistent, severe drought conditions in California. This report briefly summarizes observations for WY 2015 and compares them to previous years that had different levels of freshwater inflow.

  16. Deciphering dynamical proxy responses from lake sediments

    Science.gov (United States)

    Ramisch, Arne; Tjallingii, Rik; Hartmann, Kai; Brauer, Achim; Diekmann, Bernhard; Haberzettl, Torsten; Kasper, Thomas; Ahlborn, Marieke

    2017-04-01

    Lakes form a reliable archive of paleoenvironmental change in the terrestrial realm. Non-destructive XRF scans provide high-resolution records of element concentrations that are commonly related to past environmental change. However, XRF records of lake sediments enclose paleoenvironmental information that originates from multiple lake external and internal forcing. The variety of environmental forcing factors can complicate a direct identification of single mechanisms like climatic change from XRF or other proxy records. Here we present XRF records from several Asian lake archives, which indicate asynchronous variations of similar geochemical records since the late glacial/early Holocene. All XRF time series are characterized by damped harmonic oscillations of relative element concentrations through time. The asynchronous variations can be expressed by the frequency and the rate of damping of theses oscillations that differ between the lakes. We argue that the oscillatory behavior is a result of a feedback between the physical removal and dissolution of mineral phases in catchment soils and their subsequent enrichment and deposition within the lake. We present a numerical model, which accurately simulates major Holocene variations in the element concentration of lake records and discuss implications for the reconstruction of environmental signals from lake sediments.

  17. Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments.

    Science.gov (United States)

    Maina, Joseph; de Moel, Hans; Vermaat, Jan E; Bruggemann, J Henrich; Guillaume, Mireille M M; Grove, Craig A; Madin, Joshua S; Mertz-Kraus, Regina; Zinke, Jens

    2012-10-01

    Understanding the linkages between coastal watersheds and adjacent coral reefs is expected to lead to better coral reef conservation strategies. Our study aims to examine the main predictors of environmental proxies recorded in near shore corals and therefore how linked near shore reefs are to the catchment physical processes. To achieve these, we developed models to simulate hydrology of two watersheds in Madagascar. We examined relationships between environmental proxies derived from massive Porites spp. coral cores (spectral luminescence and barium/calcium ratios), and corresponding time-series (1950-2006) data of hydrology, climate, land use and human population growth. Results suggest regional differences in the main environmental drivers of reef sedimentation: on annual time-scales, precipitation, river flow and sediment load explained the variability in coral proxies of river discharge for the northeast region, while El Niño-Southern Oscillation (ENSO) and temperature (air and sea surface) were the best predictors in the southwest region. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Denali Ice Core Record of North Pacific Sea Surface Temperatures and the Pacific Decadal Oscillation

    Science.gov (United States)

    Polashenski, D.; Osterberg, E. C.; Winski, D.; Ferris, D. G.; Kreutz, K. J.; Wake, C. P.; Introne, D.

    2015-12-01

    Ice cores collected from high elevation alpine glaciers in the Alaska Range provide a unique opportunity to investigate changes in the regional climate of southern Alaska and the north Pacific over the past millennium. In this study, we seek to investigate changes in sea surface temperature (SST) in the north-central Pacific Ocean using the deuterium excess (d-excess) record from the Mt. Hunter ice cores collected in Denali National Park, Alaska. A collaborative research team from Dartmouth College and the Universities of Maine and New Hampshire collected two parallel ice cores to bedrock (208 m long) in May-June 2013 from the Mt. Hunter summit plateau (63º N, 151º W, 4,000 m above sea level). The cores were melted on a continuous melter system in the Dartmouth ice core lab and then analyzed for concentrations of major ions and trace elements, as well as stable water isotope ratios. The depth-age scale of the cores was determined using annual layer counting of δ18O and the concentrations of Mg, NH4, and Methanesulfonic acid (MSA) obtained by ion chromatography. The depth-age scale was validated using large, well-dated volcanic eruptions and the spike in 137Cs concentrations associated with nuclear weapons testing in 1963. Preliminary analyses indicate that the full record spans the past millennium. Analysis of the isotope data set extending back to 1938 using reanalysis data shows a positive correlation (p<0.05) between d-excess at the core site and the north-central Pacific SST. The north-central Pacific region of positive SST-d-excess correlation occurs at one node of the Pacific Decadal Oscillation (PDO), and thus the Denali cores are sensitive to PDO variability with low (high) d-excess associated with positive (negative) PDO index values. We also note a significant (p<0.05) declining trend in d-excess from 1938-2012, which we hypothesize to represent a rising proportion of Arctic moisture sources influencing Denali as Arctic temperatures and evaporation

  19. Validity of inner canthus temperature recorded by infrared thermography as a non-invasive surrogate measure for core temperature at rest, during exercise and recovery.

    Science.gov (United States)

    Fernandes, Alex Andrade; Moreira, Danilo Gomes; Brito, Ciro José; da Silva, Cristiano Diniz; Sillero-Quintana, Manuel; Pimenta, Eduardo Mendonça; Bach, Aaron J E; Garcia, Emerson Silami; Bouzas Marins, João Carlos

    2016-12-01

    Research into obtaining a fast, valid, reliable and non-invasive measure of core temperature is of interest in many disciplinary fields. Occupational and sports medicine research has attempted to determine a non-invasive proxy for core temperature particularly when access to participants is limited and thermal safety is of a concern due to protective encapsulating clothing, hot ambient environments and/or high endogenous heat production during athletic competition. This investigation aimed to determine the validity of inner canthus of the eye temperature (TEC) as an alternate non-invasive measure of intestinal core temperature (TC) during rest, exercise and post-exercise conditions. Twelve physically active males rested for 30min prior to exercise, performed 60min of aerobic exercise at 60% V̇O2max and passively recovered a further 60min post-exercise. TEC and TC were measured at 5min intervals during each condition. Mean differences between TEC and TC were 0.61°C during pre-exercise, -1.78°C during exercise and -1.00°C during post-exercise. The reliability between the methods was low in the pre-exercise (ICC=0.49 [-0.09 to 0.82]), exercise (ICC=-0.14 [-0.65 to 0.44]) and post-exercise (ICC=-0.25 [-0.70 to 0.35]) conditions. In conclusion, poor agreement was observed between the TEC values measured through IRT and TC measured through a gastrointestinal telemetry pill. Therefore, TEC is not a valid substitute measurement to gastrointestinal telemetry pill in sports and exercise science settings. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Pacific Reef Assessment and Monitoring Program: Subsurface Temperature Recorders (STRs) at selected coral reef locations across the Pacific Ocean from 2001 to 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Water temperature data are collected using subsurface temperature recorders (STRs) that aid in the monitoring of seawater temperature variability at permanent coral...

  1. Quantifying the effect of seasonal and vertical habitat tracking on planktonic foraminifera proxies

    Science.gov (United States)

    Jonkers, Lukas; Kučera, Michal

    2017-06-01

    The composition of planktonic foraminiferal (PF) calcite is routinely used to reconstruct climate variability. However, PF ecology leaves a large imprint on the proxy signal: seasonal and vertical habitats of PF species vary spatially, causing variable offsets from annual mean surface conditions recorded by sedimentary assemblages. PF seasonality changes with temperature in a way that minimises the environmental change that individual species experience and it is not unlikely that changes in depth habitat also result from such habitat tracking. While this behaviour could lead to an underestimation of spatial or temporal trends as well as of variability in proxy records, most palaeoceanographic studies are (implicitly) based on the assumption of a constant habitat. Up to now, the effect of habitat tracking on foraminifera proxy records has not yet been formally quantified on a global scale. Here we attempt to characterise this effect on the amplitude of environmental change recorded in sedimentary PF using core top δ18O data from six species. We find that the offset from mean annual near-surface δ18O values varies with temperature, with PF δ18O indicating warmer than mean conditions in colder waters (on average by -0.1 ‰ (equivalent to 0.4 °C) per °C), thus providing a first-order quantification of the degree of underestimation due to habitat tracking. We use an empirical model to estimate the contribution of seasonality to the observed difference between PF and annual mean δ18O and use the residual Δδ18O to assess trends in calcification depth. Our analysis indicates that given an observation-based model parametrisation calcification depth increases with temperature in all species and sensitivity analysis suggests that a temperature-related seasonal habitat adjustment is essential to explain the observed isotope signal. Habitat tracking can thus lead to a significant reduction in the amplitude of recorded environmental change. However, we show that this

  2. Meteosat Land Surface Temperature Climate Data Record: Achievable Accuracy and Potential Uncertainties

    Directory of Open Access Journals (Sweden)

    Anke Duguay-Tetzlaff

    2015-10-01

    Full Text Available The European Organization for the Exploitation of Meteorological Satellites’ (EUMETSAT Meteosat satellites provide the unique opportunity to compile a 30+ year land surface temperature (LST climate data record. Since the Meteosat instrument on-board Meteosat 2–7 is equipped with a single thermal channel, single-channel LST retrieval algorithms are used to ensure consistency across Meteosat satellites. The present study compares the performance of two single-channel LST retrieval algorithms: (1 A physical radiative transfer-based mono-window (PMW; and (2 a statistical mono-window model (SMW. The performance of the single-channel algorithms is assessed using a database of synthetic radiances for a wide range of atmospheric profiles and surface variables. The two single-channel algorithms are evaluated against the commonly-used generalized split-window (GSW model. The three algorithms are verified against more than 60,000 LST ground observations with dry to very moist atmospheres (total column water vapor (TCWV 1–56 mm. Except for very moist atmospheres (TCWV > 45 mm, results show that Meteosat single-channel retrievals match those of the GSW algorithm by 0.1–0.5 K. This study also outlines that it is possible to put realistic uncertainties on Meteosat single-channel LSTs, except for very moist atmospheres: simulated theoretical uncertainties are within 0.3–1.0 K of the in situ root mean square differences for TCWV < 45 mm.

  3. Carbon stable isotopes as a palaeoclimate proxy in vascular plant dominated peatlands

    Science.gov (United States)

    Amesbury, M. J.; Charman, D. J.; Newnham, R. M.; Loader, N. J.; Goodrich, J. P.; Royles, J.; Campbell, D. I.; Roland, T. P.; Gallego-Sala, A.

    2015-09-01

    Carbon stable isotope (δ13C) records from vascular plant dominated peatlands have been used as a palaeoclimate proxy, but a better empirical understanding of fractionation processes in these ecosystems is required. Here, we test the potential of δ13C analysis of ombrotrophic restiad peatlands in New Zealand, dominated by the wire rush (Empodisma spp.), to provide a methodology for developing palaeoclimatic records. We took surface plant samples alongside measurements of water table depth and (micro)climate over spatial (six sites spanning > 10° latitude) and temporal (monthly measurements over 1 year) gradients and analysed the relationships between cellulose δ13C values and environmental parameters. We found strong, significant negative correlations between δ13C and temperature, photosynthetically active radiation and growing degree days above 0 °C. No significant relationships were observed between δ13C and precipitation, relative humidity, soil moisture or water table depth, suggesting no growing season water limitation and a decoupling of the expected link between δ13C in vascular plants and hydrological variables. δ13C of Empodisma spp. roots may therefore provide a valuable temperature proxy in a climatically sensitive region, but further physiological and sub-fossil calibration studies are required to fully understand the observed signal.

  4. A system for precise temperature control of isolated nervous tissue under optical access: application to multi-electrode recordings.

    Science.gov (United States)

    Ahlers, Malte T; Ammermüller, Josef

    2013-09-30

    Since temperature severely affects all physiological processes, exact temperature control during electrophysiological measurements is indispensable. However, none of the tempering system approaches previously described is fully satisfactory for extracellular recordings with sharp multi-electrode arrays (MEAs). We developed a set-up offering a homogeneously tempered and at the same time light-transparent stage for an ex vivo preparation. The Peltier element based tempering unit of our system is physically separated from the preparation stage avoiding electrical disturbances of extracellular recordings. We implemented a digital feedback controller on a microcontroller to minimise the deviation between actual and set point temperature. Our tempering system allows operation from 10°C to 45°C with a control error in steady state between 0.052°C (RMSE) and 0.115°C (RMSE). To document the versatility of our system, we performed extracellular MEA recordings from retinal ganglion cells of isolated retina under different temperature conditions. We found strong influences on light response properties, even for small temperature changes. Currently used heating systems that allow top and bottom side optical access to a preparation typically exhibit low temperature accuracy, precision or homogeneity. Our system is adequate not only for experiments on a variety of species under physiological temperature conditions but also for studies on temperature effects on physiology in general. Though the setup was developed for the context of MEA recordings from retina it may be useful in other cases where optical access to the preparation from both, top and bottom side is required. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. A proxy analysis of urban air quality hazards in Bergen, Norway under a changing climate.

    Science.gov (United States)

    Wolf, Tobias; Esau, Igor; Reuder, Joachim

    2014-05-01

    The urban air quality in Bergen, Norway is characterized by clean air throughout most of the year interrupted by short episodes of hazardous pollution levels especially in close proximity to major road-emission sources. These pollution episodes are linked to winter time anti-cyclonic weather conditions with persistent stable temperature stratification (inversions) in the Atmospheric Boundary Layer. Although the pollution episodes are local events, the high pollution episodes are linked to large-scale persistent blockings in the atmospheric circulation. Here we present an atmospheric circulation proxy for the pollution episodes based on the ECMWF ERA-Interim reanalysis. The proxy is based on local 3-hourly instantaneous wind-speeds and directions at the 1000 hPa pressure level, and 1-day running mean temperature deviations at 2 m above ground from the 1-day running mean temperatures averaged over the full ERA-Interim record length. We tuned the thresholds for each quantity to the occurrence of events with an hourly mean NO2 concentration > 150 μg/m3 at a high pollution reference station. A condition on cloud cover had only little effect, sea-level pressure was not applicable. High pollution episodes predicted during typical low traffic days (Sundays, Christmas, New Year) were removed. The final proxy had a detection rate of 82 %, a false alarm rate of 77 % and a correct null prediction rate of 96 %. The high false alarm rate was expected because of the relaxed thresholds chosen in order to include a large fraction of possible states of atmospheric circulation that lead to hazardous air quality. Additionally, the false alarm rate was high because no constraint on the persistence of adverse meteorological conditions was set and because of the high variability of traffic, not always leading to hazardous pollution levels, even if the atmospheric circulation would allow for it. The Scandinavian index, an often used proxy for the occurrence of atmospheric circulation

  6. Munchausen syndrome by proxy: a case report.

    Science.gov (United States)

    Lieder, Holly S; Irving, Sharon Y; Mauricio, Rizalina; Graf, Jeanine M

    2005-01-01

    Munchausen syndrome by proxy is difficult to diagnose unless healthcare providers are astute to its clinical features and management. A case is presented to educate nurses and advanced practice nurses, of the nursing, medical, legal, and social complexities associated with Munchausen syndrome by proxy. This article also provides a brief review of the definition of Munchausen syndrome by proxy, its epidemiology, common features of the perpetrator, implications for healthcare personnel, and the legal and international ramifications of Munchausen syndrome by proxy.

  7. Shareholder Activism Through the Proxy Process

    NARCIS (Netherlands)

    Renneboog, L.D.R.; Szilagyi, P.G.

    2009-01-01

    This paper provides evidence on the corporate governance role of shareholder-initiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

  8. Shareholder Activism through the Proxy Process

    NARCIS (Netherlands)

    Renneboog, L.D.R.; Szilagyi, P.G.

    2009-01-01

    This paper provides evidence on the corporate governance role of shareholderinitiated proxy proposals. Previous studies debate over whether activists use proxy proposals to discipline firms or to simply advance their self-serving agendas, and whether proxy proposals are effective at all in

  9. Modelling the influence of urbanization on the 20th century temperature record of weather station De Bilt (The Netherlands)

    NARCIS (Netherlands)

    Koopmans, S.; Theeuwes, N.E.; Steeneveld, G.J.; Holtslag, A.A.M.

    2015-01-01

    Many cities have expanded during the 20th century, and consequently some weather stations are currently located closer to cities than before. Due to the urban heat island (UHI) effect, those weather stations may show a positive bias in their 2-m temperature record. In this study, we estimate the

  10. Comparison of multi-proxy data with past1000 model output over the Terminal Classic Period (800-1000 A.D.) on the Yucatan Peninsula.

    Science.gov (United States)

    Van Pelt, S.; Kohfeld, K. E.; Allen, D. M.

    2015-12-01

    The decline of the Mayan Civilization is thought to be caused by a series of droughts that affected the Yucatan Peninsula during the Terminal Classic Period (T.C.P.) 800-1000 AD. The goals of this study are two-fold: (a) to compare paleo-model simulations of the past 1000 years with a compilation of multiple proxies of changes in moisture conditions for the Yucatan Peninsula during the T.C.P. and (b) to use this comparison to inform the modeling of groundwater recharge in this region, with a focus on generating the daily climate data series needed as input to a groundwater recharge model. To achieve the first objective, we compiled a dataset of 5 proxies from seven locations across the Yucatan Peninsula, to be compared with temperature and precipitation output from the Community Climate System Model Version 4 (CCSM4), which is part of the Coupled Model Intercomparison Project Phase 5 (CMIP5) past1000 experiment. The proxy dataset includes oxygen isotopes from speleothems and gastropod/ostrocod shells (11 records); and sediment density, mineralogy, and magnetic susceptibility records from lake sediment cores (3 records). The proxy dataset is supplemented by a compilation of reconstructed temperatures using pollen and tree ring records for North America (archived in the PAGES2k global network data). Our preliminary analysis suggests that many of these datasets show evidence of drier and warmer climate on the Yucatan Peninsula around the T.C.P. when compared to modern conditions, although the amplitude and timing of individual warming and drying events varies between sites. This comparison with modeled output will ultimately be used to inform backward shift factors that will be input to a stochastic weather generator. These shift factors will be based on monthly changes in temperature and precipitation and applied to a modern daily climate time series for the Yucatan Peninsula to produce a daily climate time series for the T.C.P.

  11. Measuring SIP proxy server performance

    CERN Document Server

    Subramanian, Sureshkumar V

    2013-01-01

    Internet Protocol (IP) telephony is an alternative to the traditional Public Switched Telephone Networks (PSTN), and the Session Initiation Protocol (SIP) is quickly becoming a popular signaling protocol for VoIP-based applications. SIP is a peer-to-peer multimedia signaling protocol standardized by the Internet Engineering Task Force (IETF), and it plays a vital role in providing IP telephony services through its use of the SIP Proxy Server (SPS), a software application that provides call routing services by parsing and forwarding all the incoming SIP packets in an IP telephony network.SIP Pr

  12. Impact of prehistoric cooking practices on paleoenvironmental proxies in shell midden constituents

    Science.gov (United States)

    Müller, Peter; Staudigel, Philip; Murray, Sean T.; Westphal, Hildegard; Swart, Peter K.

    2016-04-01

    Paleoenvironmental proxy records such as oxygen isotopes of calcareous skeletal structures like fish otoliths or mollusk shells provide highest-resolution information about environmental conditions experienced by the organism. Accumulations of such skeletal structures by ancient coastal populations in so called "shell midden" deposits provide us with sub-seasonally resolved paleoclimate records covering time spans up to several millennia. Given their high temporal resolution, these deposits are increasingly used for paleoclimate reconstructions and complement our understanding of ancient climate changes. However, gathered as comestibles, most of these skeletal remains were subject to prehistoric cooking methods prior to deposition. The associated alteration of the chemical proxy signatures as well as the subsequent error for paleoenvironmental reconstructions remained almost entirely neglected so far. Here, we present clumped isotope, conventional oxygen and carbon isotopes as well as element:Ca ratios measured in modern bivalve shells after exposing them to different prehistoric cooking methods. Our data show that most cooking methods considerably alter commonly used paleoclimate proxy systems which can lead to substantial misinterpretations of ancient climate conditions. Since the magnitude of chemical alteration is not distinguishable from natural temperature variability in most coastal settings, the alteration of shell midden constituents by prehistoric cooking remains likely unnoticed in most cases. Thus, depending on the cooking method, pre-depositional heating might have introduced considerable errors into previous paleoclimate studies. However, our data also show that clumped isotope thermometry represents a suitable diagnostic tool to detect such pre-depositional cooking events and also allows differentiating between the most commonly applied prehistoric cooking methods.

  13. Elevation-Dependent Temperature Trends in the Rocky Mountain Front Range: Changes over a 56- and 20-Year Record

    Science.gov (United States)

    McGuire, Chris R.; Nufio, César R.; Bowers, M. Deane; Guralnick, Robert P.

    2012-01-01

    Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953–2008) and a shorter 20-year (1989–2008) record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM) datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data, we caution

  14. Elevation-dependent temperature trends in the Rocky Mountain Front Range: changes over a 56- and 20-year record.

    Directory of Open Access Journals (Sweden)

    Chris R McGuire

    Full Text Available Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953-2008 and a shorter 20-year (1989-2008 record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data

  15. Understanding north-western Mediterranean climate variability: a multi-proxy and multi-sequence approach based on wavelet analysis.

    Science.gov (United States)

    Azuara, Julien; Lebreton, Vincent; Jalali, Bassem; Sicre, Marie-Alexandrine; Sabatier, Pierre; Dezileau, Laurent; Peyron, Odile; Frigola, Jaime; Combourieu-Nebout, Nathalie

    2017-04-01

    Forcings and physical mechanisms underlying Holocene climate variability still remain poorly understood. Comparison of different paleoclimatic reconstructions using spectral analysis allows to investigate their common periodicities and helps to understand the causes of past climate changes. Wavelet analysis applied on several proxy time series from the Atlantic domain already revealed the first key-issues on the origin of Holocene climate variability. However the differences in duration, resolution and variance between the time-series are important issues for comparing paleoclimatic sequences in the frequency domain. This work compiles 7 paleoclimatic proxy records from 4 time-series from the north-western Mediterranean all ranging from 7000 to 1000 yrs cal BP: -pollen and clay mineral contents from the lagoonal sediment core PB06 recovered in southern France, -Sea Surface Temperatures (SST) derived from alkenones, concentration of terrestrial alkanes and their average chain length (ACL) from core KSGC-31_GolHo-1B recovered in the Gulf of Lion inner-shelf, - δ18O record from speleothems recovered in the Asiul Cave in north-western Spain, -grain size record from the deep basin sediment drift core MD99-2343 north of Minorca island. A comparison of their frequency content is proposed using wavelet analysis and cluster analysis of wavelet power spectra. Common cyclicities are assessed using cross-wavelet analysis. In addition, a new algorithm is used in order to propagate the age model errors within wavelet power spectra. Results are consistents with a non-stationnary Holocene climate variability. The Halstatt cycles (2000-2500 years) depicted in many proxies (ACL, errestrial alkanes and SSTs) demonstrate solar activity influence in the north-western Mediterranean climate. Cluster analysis shows that pollen and ACL proxies, both indicating changes in aridity, are clearly distinct from other proxies and share significant common periodicities around 1000 and 600 years

  16. Correcting the Cenozoic δ18O deep-sea temperature record

    NARCIS (Netherlands)

    Oerlemans, J.

    2004-01-01

    The oxygen isotope signal in benthic foraminifera from deep-sea cores is mainly determined by deep-ocean temperature and land ice volume. Separating the temperature and ice volume signals is a key step in understanding the evolution of Cenozoic climate. Except for the last few million years,

  17. Monitoring the body temperature of cows and calves using video recordings from an infrared thermography camera.

    Science.gov (United States)

    Hoffmann, Gundula; Schmidt, Mariana; Ammon, Christian; Rose-Meierhöfer, Sandra; Burfeind, Onno; Heuwieser, Wolfgang; Berg, Werner

    2013-06-01

    The aim of this study was to assess the variability of temperatures measured by a video-based infrared camera (IRC) in comparison to rectal and vaginal temperatures. The body surface temperatures of cows and calves were measured contactless at different body regions using videos from the IRC. Altogether, 22 cows and 9 calves were examined. The differences of the measured IRC temperatures among the body regions, i.e. eye (mean: 37.0 °C), back of the ear (35.6 °C), shoulder (34.9 °C) and vulva (37.2 °C), were significant (P infrared thermography videos has the advantage to analyze more than 1 picture per animal in a short period of time, and shows potential as a monitoring system for body temperatures in cattle.

  18. A Micro-Recorder for Measuring Skin Temperature and Sweating in Airplane Pilots

    Science.gov (United States)

    1943-12-01

    Other tabular groupings of data for individual students ars presented and the arerages disoussod* T* The records taksn in thsse preliminary... dato , time, recorder number, the exact time when the subject cot into the plane and started taxiing, the time when the plane landed, the time when...It seems possible to group the results and present them in tabular forme, The following Tables» 2 to 10 inclusive* are all similarly arranged* The re

  19. NOAA Climate Data Record for Mean Layer Temperature (Lower Stratosphere) from UCAR, Version 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Temperatures in the Lower Stratosphere (TLS) (AMSU channel 9 and MSU channel 4) CDR is generated by using National Oceanic and Atmospheric Administration (NOAA),...

  20. Record high magnetic ordering temperature in a lanthanide at extreme pressure

    Science.gov (United States)

    Lim, J.; Fabbris, G.; Haskel, D.; Schilling, J. S.

    2017-10-01

    Today’s best permanent magnet materials, SmCo5 and Nd2Fe14B, could likely be made significantly more powerful were it not necessary to dilute the strong magnetism of the rare earth ions (Sm, Nd) with the 3d transition elements (Fe, Co). Since the rare-earth metals order magnetically at relatively low temperatures T o ≤ 292 K, transition elements must be added to bring T o to temperatures well above ambient. Under pressure T o (P) for the neighboring lanthanides Gd, Tb, and Dy follows a notably nonmonotonic, but nearly identical, dependence to ∼60 GPa. At higher pressures, however, Tb and Dy exhibit highly anomalous behavior, T o for Dy soaring to temperatures well above ambient. We suggest that this anomalously high magnetic ordering temperature is an heretofore unrecognized feature of the Kondo lattice state.

  1. NOAA Climate Data Record (CDR) of MSU Level 1c Brightness Temperature, Version 1.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains Level 1c inter-calibrated brightness temperatures from the Microwave Sounding Unit (MSU) sensors onboard nine polar orbiting satellites...

  2. NOAA Climate Data Record for Mean Layer Temperature (Upper Troposphere & Lower Stratosphere) from UCAR, Version 2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Temperatures of Troposphere / Stratosphere (TTS) (AMSU channel 7 and MSU channel 3) CDR is generated by using National Oceanic and Atmospheric Administration...

  3. Wenatchee River, Washington, Water Temperature Modeling and Assessment Using Remotely Sensed Thermal Infrared and Instream Recorded Data

    Science.gov (United States)

    Cristea, N. C.; Burges, S. J.

    2004-12-01

    The stream water spatial and temporal temperature patterns of the Wenatchee River, WA are assessed based on temperature data recorded by instream data loggers in the dry season of 2002 and thermal infrared imagery from August 16th 2002. To gain insights into the possible thermal behavior of the river, the stream temperature model Qual2K (Chapra and Pelletier, 2003) is extended beyond its calibration (10-16 August 2002) and confirmation (9-11 September 2002) periods for use with different meteorological, shade and flow conditions. The temperature longitudinal profile of the Wenatchee River is influenced by the temperature regime in Lake Wenatchee, the source of the Wenatchee River. Model simulations performed at 7-day average with 2-year return period flow conditions show that the potential (maximum average across all reaches) temperature (the temperature that would occur under natural conditions) is about 19.8 deg. C. For the 7-day average with 10-year return period flow conditions the potential temperature increases to about 21.2 deg. C. The simulation results show that under normal flow and meteorological conditions the water temperature exceeds the current water quality standards. Model simulations performed under the 7-day average with 10-year return period flow conditions and a climate change scenario show that the average potential temperature across all reaches can increase by as much as 1.3 deg. C compared to the case where climate change impact is not taken into account. Thermal infrared (TIR) derived stream temperature data were useful for describing spatial distribution patterns of the Wenatchee River water temperature. The TIR and visible band images are effective tools to map cold water refugia for fish and to detect regions that can be improved for fish survival. The images collected during the TIR survey and the TIR derived stream temperature longitudinal profile helps pinpoint additional instream monitoring locations that avoid regions of backwater

  4. Novel Quantum Proxy Signature without Entanglement

    Science.gov (United States)

    Xu, Guang-bao

    2015-08-01

    Proxy signature is an important research topic in classic cryptography since it has many application occasions in our real life. But only a few quantum proxy signature schemes have been proposed up to now. In this paper, we propose a quantum proxy signature scheme, which is designed based on quantum one-time pad. Our scheme can be realized easily since it only uses single-particle states. Security analysis shows that it is secure and meets all the properties of a proxy signature, such as verifiability, distinguishability, unforgeability and undeniability.

  5. Hydroclimate variability in Scandinavia over the last millennium - insights from a climate model-proxy data comparison

    Science.gov (United States)

    Seftigen, Kristina; Goosse, Hugues; Klein, Francois; Chen, Deliang

    2017-12-01

    The integration of climate proxy information with general circulation model (GCM) results offers considerable potential for deriving greater understanding of the mechanisms underlying climate variability, as well as unique opportunities for out-of-sample evaluations of model performance. In this study, we combine insights from a new tree-ring hydroclimate reconstruction from Scandinavia with projections from a suite of forced transient simulations of the last millennium and historical intervals from the CMIP5 and PMIP3 archives. Model simulations and proxy reconstruction data are found to broadly agree on the modes of atmospheric variability that produce droughts-pluvials in the region. Despite these dynamical similarities, large differences between simulated and reconstructed hydroclimate time series remain. We find that the GCM-simulated multi-decadal and/or longer hydroclimate variability is systematically smaller than the proxy-based estimates, whereas the dominance of GCM-simulated high-frequency components of variability is not reflected in the proxy record. Furthermore, the paleoclimate evidence indicates in-phase coherencies between regional hydroclimate and temperature on decadal timescales, i.e., sustained wet periods have often been concurrent with warm periods and vice versa. The CMIP5-PMIP3 archive suggests, however, out-of-phase coherencies between the two variables in the last millennium. The lack of adequate understanding of mechanisms linking temperature and moisture supply on longer timescales has serious implications for attribution and prediction of regional hydroclimate changes. Our findings stress the need for further paleoclimate data-model intercomparison efforts to expand our understanding of the dynamics of hydroclimate variability and change, to enhance our ability to evaluate climate models, and to provide a more comprehensive view of future drought and pluvial risks.

  6. A long-term multi-proxy record of varved sediments highlights climate-induced mixing-regime shift in a large hard-water lake ~5000 years ago

    Directory of Open Access Journals (Sweden)

    Walter Finsinger

    2014-06-01

    Full Text Available The long-term terrestrial and aquatic ecosystem dynamics spanning between approximately 6200 and 4800 cal BP were investigated using pollen, diatoms, pigments, charcoal, and geochemistry from varved sediments collected in a large stratified perialpine lake, Lago Grande di Avigliana, in the Italian Alps. Marked changes were detected in diatom and pigment assemblages and in sediment composition at ~4900 cal BP. Organic matter rapidly increased and diatom assemblages shifted from oligotrophic to oligo-mesotrophic planktonic assemblages suggesting that nutrients increased at that time. Because land cover, erosion, and fire frequency did not change significantly, external nutrient sources were possibly not essential in controlling the lake-ecosystem dynamics. This is also supported by redundancy analysis, which showed that variables explaining significant amounts of variance in the diatom data were not the ones related to changes in the catchment. Instead, the broad coincidence between the phytoplankton dynamics and rising lake-levels, cooler temperatures, and stronger spring winds in the northern Mediterranean borderlands possibly points to the effects of climate change on the nutrient recycling in the lake by means of the control that climate can exert on mixing depth. We hypothesize that the increased P-release rates and higher organic-matter accumulation rates, proceeded by enhanced precipitation of iron sulphides, were possibly caused by deeper and stronger mixing leading to enhanced input of nutrients from the anoxic hypolimnion into the epilimnion. Although we cannot completely rule out the influence of minor land-cover changes due to human activities, it may be hypothesized that climate-induced cumulative effects related to mixing regime and P-recycling from sediments influenced the aquatic-ecosystem dynamics.

  7. A probabilistic analysis of human influence on recent record global mean temperature changes

    Directory of Open Access Journals (Sweden)

    Philip Kokic

    2014-01-01

    Full Text Available December 2013 was the 346th consecutive month where global land and ocean average surface temperature exceeded the 20th century monthly average, with February 1985 the last time mean temperature fell below this value. Even given these and other extraordinary statistics, public acceptance of human induced climate change and confidence in the supporting science has declined since 2007. The degree of uncertainty as to whether observed climate changes are due to human activity or are part of natural systems fluctuations remains a major stumbling block to effective adaptation action and risk management. Previous approaches to attribute change include qualitative expert-assessment approaches such as used in IPCC reports and use of ‘fingerprinting’ methods based on global climate models. Here we develop an alternative approach which provides a rigorous probabilistic statistical assessment of the link between observed climate changes and human activities in a way that can inform formal climate risk assessment. We construct and validate a time series model of anomalous global temperatures to June 2010, using rates of greenhouse gas (GHG emissions, as well as other causal factors including solar radiation, volcanic forcing and the El Niño Southern Oscillation. When the effect of GHGs is removed, bootstrap simulation of the model reveals that there is less than a one in one hundred thousand chance of observing an unbroken sequence of 304 months (our analysis extends to June 2010 with mean surface temperature exceeding the 20th century average. We also show that one would expect a far greater number of short periods of falling global temperatures (as observed since 1998 if climate change was not occurring. This approach to assessing probabilities of human influence on global temperature could be transferred to other climate variables and extremes allowing enhanced formal risk assessment of climate change.

  8. Variability in drift ice export from the Arctic Ocean to the North Icelandic Shelf over the last 8000 years: A multi-proxy evaluation

    Science.gov (United States)

    Cabedo-Sanz, Patricia; Belt, Simon T.; Jennings, Anne E.; Andrews, John T.; Geirsdóttir, Áslaug

    2016-08-01

    North Iceland represents a climatically sensitive region, in part, due to its location at the confluence of southward flowing and drift ice-laden polar waters from the Arctic Ocean delivered by the East Greenland Current, and the relatively warm and saline Irminger Current, a northerly flowing branch of the North Atlantic Current. Despite its pivotal location, there is a paucity of high resolution and long-term sea ice records for the region, with some disparities in certain previous investigations. Here, the identification of the biomarker IP25 as a reliable proxy for drift ice for North Iceland has been confirmed by measuring its abundance in surface sediments from the region and comparison of outcomes with documentary records of sea ice and other proxy data. By analysing IP25 in a well-dated marine sediment core from the North Icelandic Shelf (NIS) (MD99-2269), we also provide a high resolution (ca. 25 yr) record of drift sea ice for the region and complement this with a lower resolution record (ca. 100 yr) obtained from a second core site, located further east (JR51-GC35). Statistical treatment of equi-spaced time series reveals strong linear correlations between IP25 and a further drift ice proxy (quartz) in each core. Thus, linear regression analysis between both proxies gave correlation coefficients (R2) of 0.74 and 0.66 for MD99-2269 (25 yr) and JR51-GC35 (100 yr), respectively. Further, the individual proxies were well correlated between the two cores, with R = 0.91 and 0.77 for IP25 and quartz, respectively. The IP25-based sea ice record for MD99-2269, combined with other new biomarker and foraminifera data, and previously published proxy data for primary productivity and sea surface temperature, suggest that the paleoceanographic evolution for the NIS over the last 8 ka can be classified into three main intervals. The early mid Holocene (ca 8-6.2 cal ka BP) was characterized by relatively low or absent drift ice, low primary productivity and relatively

  9. Distribution of tetraether lipids in surface sediments of the northern South China Sea: Implications for TEX86 proxies

    Directory of Open Access Journals (Sweden)

    Huangmin Ge

    2013-03-01

    Full Text Available Archaea have unique glycerol dialkyl glycerol tetraether (GDGT lipids that can be used to develop paleotemperature proxies such as TEX86. This research is to validate proposed GDGT-proxies for paleotemperature determination in the South China Sea (SCS. Samples were collected from core-top sediments (0–5 cm in the northern SCS. Total lipids were extracted to obtain core GDGTs, which were identified and quantified using liquid chromatography-mass spectrometry (LC-MS. The abundance of isoprenoidal GDGTs (iGDGTs ranged from 271.5 ng/g dry sediment to 1266.3 ng/g dry sediment, whereas the branched GDGTs (bGDGTs, supposedly derived from terrestrial sources, ranged from 22.2 ng/g dry sediment to 56.7 ng/g dry sediment. The TEX86-derived sea surface temperatures ranged from 20.9 °C in the coast (water depth  1000 m. TEX86-derived temperatures near shore (<160 m water depth averaged 23.1 ± 2.5 °C (n = 4, which were close to the satellite-derived winter mean sea surface temperature (average 22.6 ± 1.0 °C, n = 4; whereas the TEX86-derived temperatures offshore averaged 27.4 ± 0.3 °C (n = 7 and were consistent with the satellite mean annual sea surface temperature (average 26.8 ± 0.4 °C, n = 7. These results suggest that TEX86 may record the sea surface mean annual temperature in the open ocean, while it likely records winter sea surface temperature in the shallower water.

  10. SNOW TEMPERATURE MEASUREMENTS AT VOSTOK STATION FROM AN AUTONOMOUS RECORDING SYSTEM (TAUTO: PRELIMINARY RESULTS FROM THE FIRST YEAR OPERATION

    Directory of Open Access Journals (Sweden)

    E. Lefebvre

    2012-01-01

    Full Text Available Temperature gradients in the upper layers of the snow pack are of importance for studying the emissivity properties of the snow surface with respect to microwaves used in remote sensing as well as for the heat and mass transfer in snow thickness. Gradients drive the initial snow microstructure metamorphisms that probably influence the firn properties in regard to air molecules fractionation and the air bubble enclosure process at close-off depths. As a contribution to investigation of these problems and following J.-M. Barnola initiative, we developed an autonomous recording system to monitor the temperature of the upper layers of the snow pack. The instrument was built to be autonomous and to be continuously operating within environmental conditions of the Antarctic plateau and the polar night. The apparatus which monitors temperature from the first 10 mof snow by 15 sensors of a «temperature grape» was set at Vostok station during 55th Russian Antarctic Expedition within the frame of the French Russian collaboration (GDRI Vostok. From the available hourly measurements over the first year, we present preliminary results on the thermal diffusive properties of the snow pack as well as some character of the temperature variations on the Antarctic plateau.

  11. Munchausen Syndrome by Proxy: Identification and Intervention

    Science.gov (United States)

    Walk, Alexandra; Davies, Susan C.

    2010-01-01

    This article discusses the Munchausen syndrome by proxy (MSBP), also known as "factitious disorder by proxy" (FDBP) and fabricated and/or induced illness, which is a mental illness in which a person lies about the physical or mental well-being of a person he/she is responsible for. Most often the dynamic transpires between a mother and her child.…

  12. Application of the singular spectrum analysis technique to study the recent hiatus on the global surface temperature record.

    Science.gov (United States)

    Macias, Diego; Stips, Adolf; Garcia-Gorriz, Elisa

    2014-01-01

    Global surface temperature has been increasing since the beginning of the 20th century but with a highly variable warming rate, and the alternation of rapid warming periods with 'hiatus' decades is a constant throughout the series. The superimposition of a secular warming trend with natural multidecadal variability is the most accepted explanation for such a pattern. Since the start of the 21st century, the surface global mean temperature has not risen at the same rate as the top-of-atmosphere radiative energy input or greenhouse gas emissions, provoking scientific and social interest in determining the causes of this apparent discrepancy. Multidecadal natural variability is the most commonly proposed cause for the present hiatus period. Here, we analyze the HadCRUT4 surface temperature database with spectral techniques to separate a multidecadal oscillation (MDV) from a secular trend (ST). Both signals combined account for nearly 88% of the total variability of the temperature series showing the main acceleration/deceleration periods already described elsewhere. Three stalling periods with very little warming could be found within the series, from 1878 to 1907, from 1945 to 1969 and from 2001 to the end of the series, all of them coincided with a cooling phase of the MDV. Henceforth, MDV seems to be the main cause of the different hiatus periods shown by the global surface temperature records. However, and contrary to the two previous events, during the current hiatus period, the ST shows a strong fluctuation on the warming rate, with a large acceleration (0.0085°C year(-1) to 0.017°C year(-1)) during 1992-2001 and a sharp deceleration (0.017°C year(-1) to 0.003°C year(-1)) from 2002 onwards. This is the first time in the observational record that the ST shows such variability, so determining the causes and consequences of this change of behavior needs to be addressed by the scientific community.

  13. Towards a new proxy of continental atmospheric humidity: the triple oxygen isotopic composition of plant biosilica

    Science.gov (United States)

    Alexandre, A. E.; Pauchet, S.; Landais, A.; Piel, C.; Devidal, S.; Roy, J.; Vallet-Coulomb, C.; Sonzogni, C.; Pasturel, M.; Cornuault, P.; Xin, J.; Mazur, J. C.; Prie, F.; Bentaleb, I.

    2016-12-01

    There is a serious lack of proxy suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility to make model-data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess, in water, water vapor, atmospheric oxygen, and minerals. The 17O-excess represents an alternative to d-excess for investigating relative humidity conditions that prevail during water evaporation. The 17O-excess of water results from the increase of kinetic isotopic fractionation at evaporative sites as a function of decreasing relative humidity. This mechanism occurs at large scales, i.e. during seawater evaporation or during plant canopies transpiration. Unlike deuterium-excess, 17O-excess is supposed to be insensitive to temperature and less sensitive than δD and δ18O to equilibrium fractionation during transport and precipitation. Additionally, the 17O-excess is recorded in biogenic minerals less prone to weathering than organic compounds. Here, we calibrate the 17O-excess of plant biosilica as a new air humidity proxy. First, we examined the behavior of the 17O-excess in soil water, leaf water and phytoliths in growth chambers in response to changes in relative humidity. Second, we measured the 17O-excess of soil phytolith assemblages from inter-tropical savannas and forests distributed along humidity transects. Both approaches show similar dependency of phytolith 17O-excess to relative humidity. The results allow to discuss future calibration directions aimed at estimating the precision of the obtained relationship and at quantifying the successive isotopic fractionations in play at the soil-plant-atmosphere interface, to provide a strong proxy of past atmospheric relative humidity.

  14. Evidence for cosmic ray modulation in temperature records from the South Atlantic Magnetic Anomaly region

    Energy Technology Data Exchange (ETDEWEB)

    Frigo, E. [Sao Paulo Univ. (Brazil). Dept. de Geofisica; Federal do Pampa Univ., Cacapava do Sul (Brazil); Pacca, I.G. [Sao Paulo Univ. (Brazil). Dept. de Geofisica; Pereira-Filho, A.J. [Sao Paulo Univ. (Brazil). Dept. de Ciencias Atmosfericas; Rampelloto, P.H. [Federal do Pampa Univ., Sao Gabriel (Brazil); Rigozo, N.R. [Instituto Nacional de Pesquisas Espaciais, Sao Jose dos Campos (Brazil). Div. de Geofisica Espacial

    2013-11-01

    Possible direct or indirect climatic effects related to solar variability and El Nino-Southern Oscillation (ENSO) were investigated in the southern Brazil region by means of the annual mean temperatures from four weather stations 2 degrees of latitude apart over the South Atlantic Magnetic Anomaly (SAMA) region. Four maximum temperature peaks are evident at all stations in 1940, 1958, 1977 and 2002. A spectral analysis indicates the occurrence of periodicities between 2 and 7 yr, most likely associated with ENSO, and periodicities of approximately 11 and 22 yr, normally associated with solar variability. Cross-wavelet analysis indicated that the signal associated with the 22 yr solar magnetic cycle was more persistent in the last decades, while the 11 yr sunspot cycle and ENSO periodicities were intermittent. Phase-angle analysis revealed that temperature variations and the 22 yr solar cycle were in anti-phase near the SAMA center. Results show an indirect indication of possible relationships between the variability of galactic cosmic rays and climate change on a regional scale.

  15. A wind proxy based on migrating dunes at the Baltic coast: statistical analysis of the link between wind conditions and sand movement

    Science.gov (United States)

    Bierstedt, Svenja E.; Hünicke, Birgit; Zorita, Eduardo; Ludwig, Juliane

    2017-07-01

    We statistically analyse the relationship between the structure of migrating dunes in the southern Baltic and the driving wind conditions over the past 26 years, with the long-term aim of using migrating dunes as a proxy for past wind conditions at an interannual resolution. The present analysis is based on the dune record derived from geo-radar measurements by Ludwig et al. (2017). The dune system is located at the Baltic Sea coast of Poland and is migrating from west to east along the coast. The dunes present layers with different thicknesses that can be assigned to absolute dates at interannual timescales and put in relation to seasonal wind conditions. To statistically analyse this record and calibrate it as a wind proxy, we used a gridded regional meteorological reanalysis data set (coastDat2) covering recent decades. The identified link between the dune annual layers and wind conditions was additionally supported by the co-variability between dune layers and observed sea level variations in the southern Baltic Sea. We include precipitation and temperature into our analysis, in addition to wind, to learn more about the dependency between these three atmospheric factors and their common influence on the dune system. We set up a statistical linear model based on the correlation between the frequency of days with specific wind conditions in a given season and dune migration velocities derived for that season. To some extent, the dune records can be seen as analogous to tree-ring width records, and hence we use a proxy validation method usually applied in dendrochronology, cross-validation with the leave-one-out method, when the observational record is short. The revealed correlations between the wind record from the reanalysis and the wind record derived from the dune structure is in the range between 0.28 and 0.63, yielding similar statistical validation skill as dendroclimatological records.

  16. Validation of a Climate-Data Record of the "Clear-Kky" Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Box, Jason E.; Koenig, Lora S.; DiGirolamo, Nicolo E.; Comiso, Josefino C.; Shuman, Christopher A.

    2011-01-01

    Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented since 1981. We extended and refined this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. We developed a daily and monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using an ice-surface temperature (1ST) algorithm developed for use with MODIS data. Validation of this CDR is ongoing. MODIS Terra swath data are projected onto a polar stereographic grid at 6.25-km resolution to develop binary, gridded daily and mean-monthly 1ST maps. Each monthly map also has a color-coded image map that is available to download. Also included with the monthly maps is an accompanying map showing number of days in the month that were used to calculate the mean-monthly 1ST. This is important because no 1ST decision is made by the algorithm for cells that are considered cloudy by the internal cloud mask, so a sufficient number of days must be available to produce a mean 1ST for each grid cell. Validation of the CDR consists of several facets: 1) comparisons between ISTs and in-situ measurements; 2) comparisons between ISTs and AWS data; and 3) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer (ASTER) and Enhanced Thematic Mapper Plus (ETM+). Previous work shows that Terra MODIS ISTs are about 3 C lower than in-situ temperatures measured at Summit Camp, during the winter of 2008-09 under clear skies. In this work we begin to compare surface temperatures derived from AWS data with ISTs from the MODIS CDR. The

  17. On the use of human mobility proxies for modeling epidemics.

    Directory of Open Access Journals (Sweden)

    Michele Tizzoni

    2014-07-01

    Full Text Available Human mobility is a key component of large-scale spatial-transmission models of infectious diseases. Correctly modeling and quantifying human mobility is critical for improving epidemic control, but may be hindered by data incompleteness or unavailability. Here we explore the opportunity of using proxies for individual mobility to describe commuting flows and predict the diffusion of an influenza-like-illness epidemic. We consider three European countries and the corresponding commuting networks at different resolution scales, obtained from (i official census surveys, (ii proxy mobility data extracted from mobile phone call records, and (iii the radiation model calibrated with census data. Metapopulation models defined on these countries and integrating the different mobility layers are compared in terms of epidemic observables. We show that commuting networks from mobile phone data capture the empirical commuting patterns well, accounting for more than 87% of the total fluxes. The distributions of commuting fluxes per link from mobile phones and census sources are similar and highly correlated, however a systematic overestimation of commuting traffic in the mobile phone data is observed. This leads to epidemics that spread faster than on census commuting networks, once the mobile phone commuting network is considered in the epidemic model, however preserving to a high degree the order of infection of newly affected locations. Proxies' calibration affects the arrival times' agreement across different models, and the observed topological and traffic discrepancies among mobility sources alter the resulting epidemic invasion patterns. Results also suggest that proxies perform differently in approximating commuting patterns for disease spread at different resolution scales, with the radiation model showing higher accuracy than mobile phone data when the seed is central in the network, the opposite being observed for peripheral locations. Proxies

  18. On the use of human mobility proxies for modeling epidemics.

    Science.gov (United States)

    Tizzoni, Michele; Bajardi, Paolo; Decuyper, Adeline; Kon Kam King, Guillaume; Schneider, Christian M; Blondel, Vincent; Smoreda, Zbigniew; González, Marta C; Colizza, Vittoria

    2014-07-01

    Human mobility is a key component of large-scale spatial-transmission models of infectious diseases. Correctly modeling and quantifying human mobility is critical for improving epidemic control, but may be hindered by data incompleteness or unavailability. Here we explore the opportunity of using proxies for individual mobility to describe commuting flows and predict the diffusion of an influenza-like-illness epidemic. We consider three European countries and the corresponding commuting networks at different resolution scales, obtained from (i) official census surveys, (ii) proxy mobility data extracted from mobile phone call records, and (iii) the radiation model calibrated with census data. Metapopulation models defined on these countries and integrating the different mobility layers are compared in terms of epidemic observables. We show that commuting networks from mobile phone data capture the empirical commuting patterns well, accounting for more than 87% of the total fluxes. The distributions of commuting fluxes per link from mobile phones and census sources are similar and highly correlated, however a systematic overestimation of commuting traffic in the mobile phone data is observed. This leads to epidemics that spread faster than on census commuting networks, once the mobile phone commuting network is considered in the epidemic model, however preserving to a high degree the order of infection of newly affected locations. Proxies' calibration affects the arrival times' agreement across different models, and the observed topological and traffic discrepancies among mobility sources alter the resulting epidemic invasion patterns. Results also suggest that proxies perform differently in approximating commuting patterns for disease spread at different resolution scales, with the radiation model showing higher accuracy than mobile phone data when the seed is central in the network, the opposite being observed for peripheral locations. Proxies should therefore be

  19. Ocean surface temperature variability: Large model–data differences at decadal and longer periods

    Science.gov (United States)

    Laepple, Thomas; Huybers, Peter

    2014-01-01

    The variability of sea surface temperatures (SSTs) at multidecadal and longer timescales is poorly constrained, primarily because instrumental records are short and proxy records are noisy. Through applying a new noise filtering technique to a global network of late Holocene SST proxies, we estimate SST variability between annual and millennial timescales. Filtered estimates of SST variability obtained from coral, foraminifer, and alkenone records are shown to be consistent with one another and with instrumental records in the frequency bands at which they overlap. General circulation models, however, simulate SST variability that is systematically smaller than instrumental and proxy-based estimates. Discrepancies in variability are largest at low latitudes and increase with timescale, reaching two orders of magnitude for tropical variability at millennial timescales. This result implies major deficiencies in observational estimates or model simulations, or both, and has implications for the attribution of past variations and prediction of future change. PMID:25385623

  20. Validation of a Climate-Data Record of the "Clear-Sky" Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Box, Jason E.; Koenig, Lora S.; DiGirolamo, Nicolo E.; Comiso, Josefino C.; Shuman, Christopher A.

    2011-01-01

    Surface temperatures on the Greenland Ice Sheet have been studied on the ground, using automatic weather station (AWS) data from the Greenland-Climate Network (GC-Net), and from analysis of satellite sensor data. Using Advanced Very High Frequency Radiometer (AVHRR) weekly surface temperature maps, warming of the surface of the Greenland Ice Sheet has been documented since 1981. We extended and refined this record using higher-resolution Moderate-Resolution Imaging Spectroradiometer (MODIS) data from March 2000 to the present. We developed a daily and monthly climate-data record (CDR) of the "clear-sky" surface temperature of the Greenland Ice Sheet using an ice-surface temperature (1ST) algorithm developed for use with MODIS data. Validation of this CDR is ongoing. MODIS Terra swath data are projected onto a polar stereographic grid at 6.25-km resolution to develop binary, gridded daily and mean-monthly 1ST maps. Each monthly map also has a color-coded image map that is available to download. Also included with the monthly maps is an accompanying map showing number of days in the month that were used to calculate the mean-monthly 1ST. This is important because no 1ST decision is made by the algorithm for cells that are considered cloudy by the internal cloud mask, so a sufficient number of days must be available to produce a mean 1ST for each grid cell. Validation of the CDR consists of several facets: 1) comparisons between ISTs and in-situ measurements; 2) comparisons between ISTs and AWS data; and 3) comparisons of ISTs with surface temperatures derived from other satellite instruments such as the Thermal Emission and Reflection Radiometer (ASTER) and Enhanced Thematic Mapper Plus (ETM+). Previous work shows that Terra MODIS ISTs are about 3 C lower than in-situ temperatures measured at Summit Camp, during the winter of 2008-09 under clear skies. In this work we begin to compare surface temperatures derived from AWS data with ISTs from the MODIS CDR.

  1. Creation of Single Chain of Nanoscale Skyrmion Bubbles with Record-high Temperature Stability in a Geometrically Confined Nanostripe

    KAUST Repository

    Hou, Zhipeng

    2018-01-04

    Nanoscale topologically nontrivial spin textures, such as magnetic skyrmions, have been identified as promising candidates for the transport and storage of information for spintronic applications, notably magnetic racetrack memory devices. The design and realization of a single skyrmion chain at room temperature (RT) and above in the low-dimensional nanostructures are of great importance for future practical applications. Here, we report the creation of a single skyrmion bubble chain in a geometrically confined Fe3Sn2 nanostripe with a width comparable to the featured size of a skyrmion bubble. Systematic investigations on the thermal stability have revealed that the single chain of skyrmion bubbles can keep stable at temperatures varying from RT up to a record-high temperature of 630 K. This extreme stability can be ascribed to the weak temperature-dependent magnetic anisotropy and the formation of edge states at the boundaries of the nanostripes. The realization of the highly stable skyrmion bubble chain in a geometrically confined nanostructure is a very important step toward the application of skyrmion-based spintronic devices.

  2. Creation of Single Chain of Nanoscale Skyrmion Bubbles with Record-High Temperature Stability in a Geometrically Confined Nanostripe.

    Science.gov (United States)

    Hou, Zhipeng; Zhang, Qiang; Xu, Guizhou; Gong, Chen; Ding, Bei; Wang, Yue; Li, Hang; Liu, Enke; Xu, Feng; Zhang, Hongwei; Yao, Yuan; Wu, Guangheng; Zhang, Xi-Xiang; Wang, Wenhong

    2018-02-14

    Nanoscale topologically nontrivial spin textures, such as magnetic skyrmions, have been identified as promising candidates for the transport and storage of information for spintronic applications, notably magnetic racetrack memory devices. The design and realization of a single skyrmion chain at room temperature (RT) and above in the low-dimensional nanostructures are of great importance for future practical applications. Here, we report the creation of a single skyrmion bubble chain in a geometrically confined Fe 3 Sn 2 nanostripe with a width comparable to the featured size of a skyrmion bubble. Systematic investigations on the thermal stability have revealed that the single chain of skyrmion bubbles can keep stable at temperatures varying from RT up to a record-high temperature of 630 K. This extreme stability can be ascribed to the weak temperature-dependent magnetic anisotropy and the formation of edge states at the boundaries of the nanostripes. The realization of the highly stable skyrmion bubble chain in a geometrically confined nanostructure is a very important step toward the application of skyrmion-based spintronic devices.

  3. Paleolimnological records of recent changes in glacier status, precipitation, and temperature in the Rwenzori Mountains, Uganda-D. R. Congo

    Science.gov (United States)

    Russell, J. M.; Eggermont, H. R.; Loomis, S.; Verschuren, D.

    2008-12-01

    Understanding the climatic controls on the status of tropical glaciers is vitally important to assessing past and present global climate change and the future stability of tropical alpine glaciers and ecosystems. Lack of high-resolution, independent reconstructions of trends in tropical temperatures, precipitation, and glacier extent severely limits our ability to decipher the causes of past glacier fluctuations. Here we investigate recent (the last ca. 1,000 years) changes in sedimentation and climate using lakes in the Rwenzori Mountains, Uganda-D. R. Congo. Clastic mineral input to 5 lakes situated downstream from Rwenzori glaciers is high and stable for much of the past millennium, but declines rapidly from 1870 AD toward the present. In contrast, 11 Rwenzori lakes without glaciers in their catchment show little to no such change. We therefore interpret the decline in clastic mineral input to reflect the retreat of Rwenzori glaciers from expanded positions reached during the 'Little Ice Age' (LIA). Comparison of this glacier history to organic geochemical records of temperature and hydrology from regional lakes indicates that the Rwenzori glaciers expanded during a cool yet dry LIA, and retreated during the relatively warm, moist conditions of the past century. Rising temperature thus played an important, if not dominant role in the retreat of the Rwenzori's glaciers from their LIA positions. perhaps due to the effects of air temperature on the phase (rain vs. snow) of precipitation falling on alpine glaciers.

  4. Monitoring And Recording Data For Solar Radiation Temperature And Charging Current

    Directory of Open Access Journals (Sweden)

    Aung Bhone Myint

    2015-08-01

    Full Text Available A data logger based on 8051 microcontroller has been implemented in this project to measure the solar radiation temperature and charging current. Development of a low-cost data logger can easily be made and easily be used to convert the analog signal of physical parameters of various test or other purposes of engineering. By using a suitable program code it can be used to read the value digitally with a PC. Our aim is to provide with a module and a software package when installed in a computer one can remotely acquire and monitor several numbers of the same or different types of signals sequentially at a time. Signals obtained from various sensors have been effectively conditioned. Now interfacing these signals using ADC with the Bluetooth module port of a computer satisfies the very goal of data acquisition. Proposed system provides better performance and has low cost versatile portable.

  5. Comment on Boretti (2013), `Statistical analysis of the temperature records for the Northern Territory of Australia'

    Science.gov (United States)

    Trewin, Blair C.; Jones, David A.

    2015-04-01

    Boretti (Theor Appl Clim 114:567-573, 2013) presents an analysis of observed temperature trends in the Northern Territory, Australia, and claims that this analysis is inconsistent with trends reported by the Australian Bureau of Meteorology and thus that the Bureau of Meteorology results are flawed. This paper presents evidence that the results presented by Boretti (2013) are at least partly attributable to his failure to account for inhomogeneities in the underlying station data and to the use of time periods for trends which are different to those in the Bureau of Meteorology analyses with which he is comparing them. The evidence, as presented in this paper, therefore fails to support his conclusions of inconsistencies between the Bureau of Meteorology analyses and the station data.

  6. Data on records of indoor temperature and relative humidity in a University building

    Directory of Open Access Journals (Sweden)

    O. Irulegi

    2017-08-01

    Full Text Available Good indoor comfort and air quality are essential for correct educational development. Most reports in this field focus on primary and secondary school buildings, with numerous projects conducted in the Mediterranean Zone. However, little has been done in the context of university buildings. Data on indoor temperature and relative humidity data acquired trough field surveys of a seminar room located in the Architecture Faculty in San Sebastian (Spain is provided in this paper. The seminar room was monitored during a typical spring week. The data presented in the article are related to the research article entitled Retrofit strategies towards Net Zero Energy Educational Buildings: a case study at the University of the Basque Country (Ref. 0378–7788.

  7. Deep-focus earthquake analogs recorded at high pressure and temperature in the laboratory.

    Science.gov (United States)

    Schubnel, Alexandre; Brunet, Fabrice; Hilairet, Nadège; Gasc, Julien; Wang, Yanbin; Green, Harry W

    2013-09-20

    Phase transformations of metastable olivine might trigger deep-focus earthquakes (400 to 700 kilometers) in cold subducting lithosphere. To explore the feasibility of this mechanism, we performed laboratory deformation experiments on germanium olivine (Mg2GeO4) under differential stress at high pressure (P = 2 to 5 gigapascals) and within a narrow temperature range (T = 1000 to 1250 kelvin). We found that fractures nucleate at the onset of the olivine-to-spinel transition. These fractures propagate dynamically (at a nonnegligible fraction of the shear wave velocity) so that intense acoustic emissions are generated. Similar to deep-focus earthquakes, these acoustic emissions arise from pure shear sources and obey the Gutenberg-Richter law without following Omori's law. Microstructural observations prove that dynamic weakening likely involves superplasticity of the nanocrystalline spinel reaction product at seismic strain rates.

  8. Environmental and Physiological Influences on the TEX86 Proxy: Results from Continuous Culture Studies and Stable Carbon Isotope Analyses

    Science.gov (United States)

    Pearson, A.; Hurley, S.; Elling, F. J.; Koenneke, M.; Santoro, A. E.; Buchwald, C.; Wankel, S. D.; Hinrichs, K. U.; Zhang, Y.; Shah Walter, S. R.

    2015-12-01

    Membrane lipids of marine Archaea - known as GDGTs - are the basis of the TEX86 sea surface temperature (SST) paleoproxy. GDGTs are ubiquitous in marine sediments, and their broad distribution and high preservation potential have led to an ever-increasing use of TEX86. The planktonic Thaumarchaeota that are believed to be the major sources of GDGTs to marine sediments are autotrophic nitrifiers, assimilating carbon directly from dissolved CO2. Therefore the δ13C values of GDGTs additionally provide information about the DIC system and paleoproductivity. However, as for all biological proxies, understanding the physiology and biochemistry of the responsible organisms is essential to understanding how the proxies work. From this perspective, the TEX86-SST proxy is uniquely perplexing: How is it possible that multiple approaches to calibration show a good correlation between TEX86 and SSTs, when maximum activity of Thaumarchaeota is near and below the base of the photic zone? Here we show data from two studies that help address this question. Analyses of GDGT δ13C values show that the dominant GDGT flux to sediments is not from the sea surface. The data are measured on intact GDGTs purified by orthogonal dimensions of HPLC, followed by measurement of δ13C values on a Spooling Wire Microcombustion (SWiM)-IRMS with 1σ precision of ±0.2‰ and accuracy of ±0.3‰. Using this approach, we confirm that GDGTs, generally around -19.0‰ to -18.5‰, are isotopically "heavy" compared to other marine lipids, and that crenarchaeol in particular is a good tracer of water column GDGT export. In parallel, we investigated the mechanistic underpinning of the TEX86 proxy using isothermal culture studies of the ammonia-oxidizing thaumarchaeon Nitrosopumilus maritimus SCM1 to explore the relationship between TEX86 and growth conditions. Evidence suggests that growth rate and electron donor supply are important controls on GDGT ratios and that TEX86 scales with the in-situ rate of

  9. Appraising timing response of paleoenvironmental proxies to the Bond cycle in the western Mediterranean over the last 20 kyr

    Science.gov (United States)

    Rodrigo-Gámiz, Marta; Martínez-Ruiz, Francisca; Rodríguez-Tovar, Francisco J.; Pardo-Igúzquiza, Eulogio; Ortega-Huertas, Miguel

    2017-07-01

    The timing of climate responses to the Bond cycle is investigated in the western Mediterranean. Periodicities had been previously reported in a marine sediment record from this region spanning the last 20 kyr, and registered by diverse paleoenvironmental proxies, in particular those associated with terrigenous input, redox conditions, productivity, sea surface temperature (SST) and salinity. Further cross-spectral analyses on these time series reveal leads-lags in the 1400 year climate cycle. Considering as reference a terrigenous input proxy (the K/Al ratio), all the paleoenvironmental proxies displayed time shifts varying from ca. 700 year to ca. 350 year. SST and salinity variations show a first leaded response with the inflow of cold and less salty Atlantic waters. Followed by a time lead of 525 year, progresively arid conditions with an increase of eolian dust transport to the area, given by the Zr/Al signal, are observed. The intensification of dust transport could have triggered a latest biological response, lead by 350 year, with an increase of productivity, as suggested by the Ba/Al ratio. Lastly changes in the Mediterranean thermohaline circulation, indicated by a selected redox proxy (the U/Th ratio), are observed. These results support that the oceanic response triggered the atmospheric response to the Bond cycle in the western Mediterranean. Changes in the North Atlantic Oscillation mode and in the Inter-Tropical Convergence Zone migrations with variations in the monsoon activity or Saharan winds system, are considered as main forcing mechanisms, with a complex relationship of the involved phenomena.

  10. The effects of metamorphism on iron mineralogy and the iron speciation redox proxy

    Science.gov (United States)

    Slotznick, Sarah P.; Eiler, John M.; Fischer, Woodward W.

    2018-03-01

    As the most abundant transition metal in the Earth's crust, iron is a key player in the planetary redox budget. Observations of iron minerals in the sedimentary record have been used to describe atmospheric and aqueous redox environments over the evolution of our planet; the most common method applied is iron speciation, a geochemical sequential extraction method in which proportions of different iron minerals are compared to calibrations from modern sediments to determine water-column redox state. Less is known about how this proxy records information through post-depositional processes, including diagenesis and metamorphism. To get insight into this, we examined how the iron mineral groups/pools (silicates, oxides, sulfides, etc.) and paleoredox proxy interpretations can be affected by known metamorphic processes. Well-known metamorphic reactions occurring in sub-chlorite to kyanite rocks are able to move iron between different iron pools along a range of proxy vectors, potentially affecting paleoredox results. To quantify the effect strength of these reactions, we examined mineralogical and geochemical data from two classic localities where Silurian-Devonian shales, sandstones, and carbonates deposited in a marine sedimentary basin with oxygenated seawater (based on global and local biological constraints) have been regionally metamorphosed from lower-greenschist facies to granulite facies: Waits River and Gile Mountain Formations, Vermont, USA and the Waterville and Sangerville-Vassalboro Formations, Maine, USA. Plotting iron speciation ratios determined for samples from these localities revealed apparent paleoredox conditions of the depositional water column spanning the entire range from oxic to ferruginous (anoxic) to euxinic (anoxic and sulfidic). Pyrrhotite formation in samples highlighted problems within the proxy as iron pool assignment required assumptions about metamorphic reactions and pyrrhotite's identification depended on the extraction techniques

  11. Petrological and geochemical records of short-lived, high temperature metamorphism during exhumation of the Sulu UHP metamorphic terrane

    Science.gov (United States)

    Zong, K.; Liu, Y.; Zhang, X.; Ye, Y.; Gao, C.

    2010-12-01

    The Dabie-Sulu terrane of east-central China is the largest and most well known ultrahigh-pressure (UHP) metamorphic terrane in the world, which has become one of the most important places to study continental subduction-related UHP metamorphism. In the past two decades, numerous petrological, geochemical, petrophysical and tectonophysical studies were carried out in the Dabie-Sulu UHP metamorphic terrane. However, almost all of these studies have focused on UHP metamorphic processes, while only a few studies have focused on the thermal evolution. Here we present a detailed petrological and geochemical study on the southern Sulu UHP eclogites in order to constrain the “hot” exhumation of the Sulu UHP metamorphic terrane. Eclogite-hosted garnet-spinel-corundum-quartz-bearing titanohematite veins near the main hole of the Chinese Continental Scientific Drilling Project (CCSD-MH) are described for the first time in the Sulu UHP metamorphic terrane. A vein composed of titanohematite + ilmenite + hematite + spinel + garnet + corundum + quartz + K-feldspar + albite was studied in detail. The unusual mineral assemblage of garnet + spinel + corundum + quartz implies that this vein could have experienced high temperatures (>900 oC). Although within garnets showed well-defined Mg and Mn diffusion zoning in the rim as a result of the high temperature event, slight Mg and Mn growth zoning was preserved in the core. Thus, we suggest that the Sulu UHP terrane could have experienced a short-lived, high-temperature stage during exhumation. This is consistent with trace element zoning recorded by garnet, omphacite and apatite and much higher temperatures recorded by rutiles and zircons with ages of ~200 Ma in the CCSD-MH eclogites. We speculate that slab breakoff may have caused asthenospheric upwelling, which could have provided a heat pulse for the short-lived, high-temperature metamorphism in the Sulu UHP terrane. Such high temperature stage could have contributed to the

  12. Three-dimensional temperature fields of the North Patagonian Sea recorded by Magellanic penguins as biological sampling platforms

    Science.gov (United States)

    Sala, Juan E.; Pisoni, Juan P.; Quintana, Flavio

    2017-04-01

    Temperature is a primary determinant of biogeographic patterns and ecosystem processes. Standard techniques to study the ocean temperature in situ are, however, particularly limited by their time and spatial coverage, problems which might be partially mitigated by using marine top predators as biological platforms for oceanographic sampling. We used small archival tags deployed on 33 Magellanic penguins (Spheniscus magellanicus), and obtained 21,070 geo-localized profiles of water temperature, during late spring of 2008, 2011, 2012 and 2013; in a region of the North Patagonian Sea with limited oceanographic records in situ. We compared our in situ data of sea surface temperature (SST) with those available from satellite remote sensing; to describe the three-dimensional temperature fields around the area of influence of two important tidal frontal systems; and to study the inter-annual variation in the three-dimensional temperature fields. There was a strong positive relationship between satellite- and animal-derived SST data although there was an overestimation by remote-sensing by a maximum difference of +2 °C. Little inter-annual variability in the 3-dimensional temperature fields was found, with the exception of 2012 (and to a lesser extent in 2013) where the SST was significantly higher. In 2013, we found weak stratification in a region which was unexpected. In addition, during the same year, a warm small-scale vortex is indicated by the animal-derived temperature data. This allowed us to describe and better understand the dynamics of the water masses, which, so far, have been mainly studied by remote sensors and numerical models. Our results highlight again the potential of using marine top predators as biological platforms to collect oceanographic data, which will enhance and accelerate studies on the Southwest Atlantic Ocean. In a changing world, threatened by climate change, it is urgent to fill information gaps on the coupled ocean-atmosphere system

  13. Decadally-resolved sea surface temperature and salinity records of the East Sea (Japan Sea) over the last 2000 years

    Science.gov (United States)

    Lee, K. E.; Park, W.; Rhee, T. S.

    2013-12-01

    The East Asia monsoon is an important component of Earth's climate system, yet its dynamical processes are not sufficiently understood. Previous studies indicate a strong coupling between monsoon circulation and northern hemisphere climate change on interannual to decadal time scales. However, our understanding of monsoon variability and teleconnections to high- and low-latitude mechanisms on longer time scale remains insufficient. In this study, decadally-resolved continuous sea surface temperature and salinity records over the last 2000 years from alkenone and planktonic foraminiferal oxygen isotope ratio analyses of East Sea (Japan Sea) marine sediments have been reconstructed to investigate East Asia monsoon variability. The results show that during the Medieval Climate Anomaly, East Asia was characterized by surface warming with a strengthened summer monsoon. Summer monsoon-related precipitation increased and pluvials possibly dominated in the region at that time. On the other hand, Asia monsoon failure and severe drought is characteristic of the Little Ice Age. Comparisons of the records with other paleoclimate records indicate a possible connection between changes in the mid-latitude East Asia monsoon, Arctic Oscillation (AO)/North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO) over the period.

  14. Record-low sintering-temperature (600 °C) of solid-oxide fuel cell electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Dasari, Hari Prasad, E-mail: energyhari@nitk.edu.in [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Chemical Engineering Department, National Institute of Technology Karnataka, Mangalore 575025, Karnataka (India); Ahn, Kiyong; Park, Sun-Young; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Kim, Byung-Kook; Lee, Hae-Weon [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Lee, Jong-Ho, E-mail: jongho@kist.re.kr [High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of)

    2016-07-05

    One of the major problems arising with Solid-Oxide Fuel Cell (SOFC) electrolyte is conventional sintering which requires a very high temperature (>1300 °C) to fully density the electrolyte material. In the present study, the sintering temperature of SOFC electrolyte is drastically decreased down to 600 °C. Combinational effects of particle size reduction, liquid-phase sintering mechanism and microwave sintering resulted in achieving full density in such a record-low sintering temperature. Gadolinium doped Ceria (GDC) nano-particles are synthesized by co-precipitation method, Lithium (Li), as an additional dopant, is used as liquid-phase sintering aid. Microwave sintering of this electrolyte material resulted in decreasing the sintering temperature to 600 °C. Micrographs obtained from Scanning/Transmission Electron Microscopy (SEM/TEM) clearly pointed a drastic growth in grain-size of Li-GDC sample (∼150 nm) than compared to GDC sample (<30 nm) showing the significance of Li addition. The sintered Li-GDC samples displayed an ionic conductivity of ∼1.00 × 10{sup −2} S cm{sup −1} at 600 °C in air and from the conductivity plots the activation energy is found to be 0.53 eV. - Highlights: • Sintering temperature is drastically decreased to 600 °C. • Key factors: Particle size reduction, liquid-phase and microwave sintering. • Nano-Li-GDC sample has ionic conductivity of ∼1.00 × 10{sup −2} S cm{sup −1} at 600 °C in air.

  15. Use and Limitations of a Climate-Quality Data Record to Study Temperature Trends on the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Comiso, Josefino C.; Shuman, Christopher A.; Koenig, Lora S.; DiGirolamo, Nicolo E.

    2011-01-01

    Enhanced melting of the Greenland Ice Sheet has been documented in recent literature along with surface-temperature increases measured using infrared satellite data since 1981. Using a recently-developed climate-quality data record, 11- and 12-year trends in the clear-sky ice-surface temperature (IST) of the Greenland Ice Sheet have been studied using the Moderate-Resolution Imaging Spectroradiometer (MODIS) IST product. Daily and monthly MODIS ISTs of the Greenland Ice Sheet beginning on 1 March 2000 and continuing through 31 December 2010 are now available at 6.25-km spatial resolution on a polar stereographic grid as described in Hall et al. (submitted). This record will be elevated in status to a climate-data record (CDR) when more years of data become available either from the MODIS on the Terra or Aqua satellites, or from the Visible Infrared Imager Radiometer Suite (VIIRS) to be launched in October 2011. Maps showing the maximum extent of melt for the entire ice sheet and for the six major drainage basins have been developed from the MODIS IST dataset. Twelve-year trends of the duration of the melt season on the ice sheet vary in different drainage basins with some basins melting progressively earlier over the course of the study period. Some (but not all) of the basins also show a progressively-longer duration of melt. IST 12-year trends are compared with in-situ data, and climate data from the Modern Era Retrospective-Analysis for Research and Applications (MERRA) Reanalysis.

  16. Understanding controls on organic (Uk’37 and TEX86) and inorganic (Mg/Ca) SST proxies: insights from a long term Mozambique Channel sediment trap study

    Science.gov (United States)

    Castañeda, I. S.; Fallet, U.; Brummer, G. A.; Sinninghe Damsté, J. S.; Schouten, S.

    2009-12-01

    In 2003, an array of moorings equipped with instruments to measure temperature, salinity and water mass transport was placed across the Mozambique Channel as part of the Long-term Ocean Currents Observation (LOCO) Project. In addition, a sediment trap in the deep channel at 2011 m collected material at 21 day intervals from November 2003 until the present. These sediment trap samples, in combination with in situ and satellite-derived SST measurements, provide a unique opportunity to examine and directly compare organic and inorganic SST proxies. In this study we measured two organic SST proxies, the Uk’37 Index, which is based on the ratio of long-chain di- and triunsaturated ketones produced by haptophyte algae, and the more recently developed TEX86 proxy, which is based on glycerol dialkyl glycerol tetraethers (GDGTs) produced by Marine Group 1 Crenarchaeota. We also analyzed Mg/Ca ratios from two species of surface-dwelling foraminifera, G. ruber and G. trilobus, which provide an inorganic SST proxy. The results obtained up to now show that TEX86-based SST reconstructions capture the mean annual temperature of the study location accurately (mean annual SST is 28.1°C and TEX86 mean annual SST is 28.3°C); however, seasonal variability is not reflected by the TEX86 measurements. In contrast, the Mg/Ca records of G. ruber and G. trilobus, capture the seasonal variability in SST but display a slight offset relative to each other, with G. ruber typically 2 to 3°C warmer than G. trilobus. The Uk’37 Index was nearly always near unity due to the absence of the C37:3 alkenone, showing that this proxy is unable to capture SST at this tropical location. The differences between the organic and inorganic proxies might be due to the different sinking rates and lateral transport effects. To further investigate controls on the TEX86 proxy, we are currently examining intact polar lipids (IPLs) of GDGTs from the most recent year of sediment trap material. IPLs are more

  17. New proxy replacement algorithm for multimedia streaming

    Science.gov (United States)

    Wong, Hau Ling; Lo, Kwok-Tung

    2001-11-01

    Proxy servers play an important role in between servers and clients in various multimedia systems on the Internet. Since proxy servers do not have an infinite-capacity cache for keeping all the continuous media data, the challenge for the replacement policy is to determine which streams should be cached or removed from the proxy server. In this paper, a new proxy replacement algorithm, named the Least Popular Used (LPU) caching algorithm, is proposed for layered encoded multimedia streams in the Internet. The LPU method takes both the short-term and long-term popularity of the video into account in determining the replacement policy. Simulation evaluation shows that our proposed scheme achieves better results than some existing methods in term of the cache efficiency and replacement frequency under both static and dynamic access environments.

  18. 78 FR 70987 - Proxy Advisory Firm Roundtable

    Science.gov (United States)

    2013-11-27

    ... of proxy advisory firm use by investment advisers and institutional investors and potential changes... Special Counsel, Division of Investment Management, at 202-551-6700, or Raymond Be, Special Counsel...

  19. A serial Munchausen syndrome by proxy

    National Research Council Canada - National Science Library

    Esra Unal; Volkan Unal; Ali Gul; Mustafa Celtek; Behzat Diken; Ibrahim Balcioglu

    2017-01-01

    Munchausen syndrome by proxy (MSBP) is a form of child abuse that describes children whose parents or caregivers invent illness stories and substantiate the stories by fabricating false physical signs...

  20. Seizures and Munchausen Syndrome by Proxy

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2002-05-01

    Full Text Available The prevalence, morbidity and mortality, diagnosis and management of cases of fabricated seizures and child abuse (Munchausen syndrome by proxy (MSbp are assessed by pediatricians at the University of Wales College of Medicine, Cardiff, UK.

  1. NOAA Climate Data Record (CDR) of GPS RO-Calibrated AMSU Channel 7 (Temperatures of Troposphere / Stratosphere, TTS), Version 1.0 (Version Superseded)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Climate Data Records (CDR) for Channel 7 contains Radio Occulation (RO) calibrated brightness temperatures from AMSU-A channel 7 measurements at 54.9 GHz from...

  2. Seawater Temperature and Salinity Moored Time-Series Records, Collected During 2010 and 2011 in Vieques Sound and Virgin Passage (NODC Accession 0088063)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Sea-Bird SBE37SM MicroCat Conductivity/Temperature (CT) recorders were deployed between March 2010 and April 2011 on shallow water moorings located in Vieques Sound,...

  3. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.36784, Lat: 28.27774 (WGS84); Sensor Depth: 0.30m; Data Range: 20020926-20030727.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62172, Lat: 00.80645 (WGS84); Sensor Depth: 18.89m; Data Range: 20060128-20080205.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  5. CRED Subsurface Temperature Recorder (STR); NWHI, LAY; Long: -171.73890, Lat: 25.77954 (WGS84); Sensor Depth: 1.21m; Data Range: 20040924-20060910.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); AMSM, ROS; Long: -168.16883, Lat: -14.54871 (WGS84); Sensor Depth: 31.40m; Data Range: 20080313-20100303.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); MHI, HAW; Long: -155.90161, Lat: 19.07380 (WGS84); Sensor Depth: 17.68m; Data Range: 20081101-20101011.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. CRED Subsurface Temperature Recorder (STR); PRIA, WAK; Long: 166.65107, Lat: 19.30617 (WGS84); Sensor Depth: 13.11m; Data Range: 20070505-20090323.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  9. CRED Subsurface Temperature Recorder (STR); MHI, OAH; Long: -158.13685, Lat: 21.35464 (WGS84); Sensor Depth: 17.98m; Data Range: 20080514-20090206.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.62487, Lat: -14.16393 (WGS84); Sensor Depth: 6.40m; Data Range: 20040207-20050720.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); AMSM, TUT; Long: -170.56222, Lat: -14.28368 (WGS84); Sensor Depth: 8.23m; Data Range: 20050804-20060218.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); PRIA, JAR; Long: -160.00803, Lat: -00.36902 (WGS84); Sensor Depth: 6.40m; Data Range: 20040328-20060102.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); PRIA, KIN; Long: -162.38440, Lat: 06.38252 (WGS84); Sensor Depth: 6.40m; Data Range: 20060330-20080404.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.88215, Lat: 27.78250 (WGS84); Sensor Depth: 12.50m; Data Range: 20060913-20060922.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  15. CRED Subsurface Temperature Recorder (STR); PRIA, JAR; Long: -159.99663, Lat: -00.38183 (WGS84); Sensor Depth: 9.80m; Data Range: 20040328-20060321.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  16. CRED Subsurface Temperature Recorder (STR); PRIA, WAK; Long: 166.62868, Lat: 19.28032 (WGS84); Sensor Depth: 12.19m; Data Range: 20070505-20090324.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  17. CRED Subsurface Temperature Recorder (STR); NWHI, KUR; Long: -178.36842, Lat: 28.42927 (WGS84); Sensor Depth: 0.60m; Data Range: 20030805-20041006.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  18. CRED Subsurface Temperature Recorder (STR); NWHI, LAY; Long: -171.72941, Lat: 25.75893 (WGS84); Sensor Depth: 0.91m; Data Range: 20040924-20060730.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  19. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.26132, Lat: 23.76897 (WGS84); Sensor Depth: 3.96m; Data Range: 20040917-20060905.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  20. CRED Subsurface Temperature Recorder (STR); CNMI, SAR; Long: 145.76789, Lat: 16.71058 (WGS84); Sensor Depth: 6.10m; Data Range: 20050918-20070524.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  1. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.83133, Lat: 27.89797 (WGS84); Sensor Depth: 1.83m; Data Range: 20030802-20040927.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  2. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.26198, Lat: 23.76883 (WGS84); Sensor Depth: 11.28m; Data Range: 20091009-20100513.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  3. CRED Subsurface Temperature Recorder (STR); AMSM, TUT; Long: -170.76260, Lat: -14.36451 (WGS84); Sensor Depth: 20.10m; Data Range: 20040225-20060116.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. CRED Subsurface Temperature Recorder (STR); AMSM, ROS; Long: -168.16885, Lat: -14.54882 (WGS84); Sensor Depth: 31.09m; Data Range: 20060308-20080312.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  5. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.88217, Lat: 27.78245 (WGS84); Sensor Depth: 13.11m; Data Range: 20070805-20080923.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.53972, Lat: 25.38417 (WGS84); Sensor Depth: 1.50m; Data Range: 20021003-20030719.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.65193, Lat: -14.18062 (WGS84); Sensor Depth: 18.90m; Data Range: 20080228-20100310.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. CRED Subsurface Temperature Recorder (STR); AMSM, TUT; Long: -170.56225, Lat: -14.28368 (WGS84); Sensor Depth: 8.84m; Data Range: 20090529-20100225.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  9. CRED Subsurface Temperature Recorder (STR); CNMI, AGU; Long: 145.53725, Lat: 14.84778 (WGS84); Sensor Depth: 7.60m; Data Range: 20050928-20070517.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); CNMI, AGU; Long: 145.53723, Lat: 14.84778 (WGS84); Sensor Depth: 8.23m; Data Range: 20070518-20090410.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); CNMI, SAR; Long: 145.76892, Lat: 16.71057 (WGS84); Sensor Depth: 1.00m; Data Range: 20030824-20050918.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62163, Lat: 00.80647 (WGS84); Sensor Depth: 38.40m; Data Range: 20061028-20080207.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62401, Lat: 00.81480 (WGS84); Sensor Depth: 14.63m; Data Range: 20080207-20100203.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62133, Lat: 00.80660 (WGS84); Sensor Depth: 3.00m; Data Range: 20060128-20080207.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  15. CRED Subsurface Temperature Recorder (STR); PRIA, KIN; Long: -162.34216, Lat: 06.39241 (WGS84); Sensor Depth: 6.71m; Data Range: 20080405-20100414.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  16. CRED Subsurface Temperature Recorder (STR); CNMI, ALA; Long: 145.81870, Lat: 17.58744 (WGS84); Sensor Depth: 6.70m; Data Range: 20070527-20090504.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  17. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.62661, Lat: -14.18177 (WGS84); Sensor Depth: 11.28m; Data Range: 20080229-20100311.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  18. NOAA Climate Data Record of Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU-A) Mean Layer Temperature, Version 3.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The dataset contains three channel-based, monthly gridded atmospheric layer temperature Climate Data Records generated by merging nine MSU NOAA polar orbiting...

  19. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.64297, Lat: 21.01736 (WGS84); Sensor Depth: 12.19m; Data Range: 20081023-20101018.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  20. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.49718, Lat: 20.63030 (WGS84); Sensor Depth: 11.58m; Data Range: 20050807-20101017.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  1. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.42031, Lat: 20.59198 (WGS84); Sensor Depth: 14.90m; Data Range: 20060805-20071009.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  2. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.42031, Lat: 20.59198 (WGS84); Sensor Depth: 14.90m; Data Range: 20071009-20081018.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  3. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.58448, Lat: 20.79079 (WGS84); Sensor Depth: 11.89m; Data Range: 20081024-20100326.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.15112, Lat: 20.86452 (WGS84); Sensor Depth: 14.63m; Data Range: 20060819-20080918.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  5. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.42033, Lat: 20.59195 (WGS84); Sensor Depth: 14.63m; Data Range: 20081018-20101020.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.88093, Lat: 27.78168 (WGS84); Sensor Depth: 38.10m; Data Range: 20080923-20100913.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); PRIA, KIN; Long: -162.34218, Lat: 06.39240 (WGS84); Sensor Depth: 7.30m; Data Range: 20060329-20080405.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. NOAA Climate Data Record (CDR) of Intersatellite Calibrated Clear-Sky HIRS Channel 12 Brightness Temperature, Version 2.6 (Superseded)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) of Inter-Satellite Calibrated Clear-Sky High Resolution Infrared Radiation Sounder (HIRS) Channel 12 brightness temperatures...

  9. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.65219, Lat: -14.18017 (WGS84); Sensor Depth: 6.10m; Data Range: 20080228-20100311.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); NWHI, LIS; Long: -173.91583, Lat: 25.96762 (WGS84); Sensor Depth: 10.36m; Data Range: 20081004-20090910.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); NWHI, LAY; Long: -171.74242, Lat: 25.77248 (WGS84); Sensor Depth: 3.35m; Data Range: 20060910-20080920.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); PRIA, PAL; Long: -162.12820, Lat: 05.89635 (WGS84); Sensor Depth: 10.97m; Data Range: 20090916-20100408.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.65947, Lat: -14.18290 (WGS84); Sensor Depth: 1.50m; Data Range: 20040825-20060505.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. CRED Subsurface Temperature Recorder (STR); NWHI, LIS; Long: -173.91588, Lat: 25.96771 (WGS84); Sensor Depth: 9.75m; Data Range: 20060925-20081004.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  15. CRED Subsurface Temperature Recorder (STR); NWHI, KUR; Long: -178.30620, Lat: 28.44760 (WGS84); Sensor Depth: 1.22m; Data Range: 20060918-20080929.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  16. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.32334, Lat: 28.24437 (WGS84); Sensor Depth: 0.50m; Data Range: 20030729-20041001.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  17. CRED Subsurface Temperature Recorder (STR); PRIA, PAL; Long: -162.06217, Lat: 05.88235 (WGS84); Sensor Depth: 15.84m; Data Range: 20060324-20080108.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  18. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.40178, Lat: 28.19358 (WGS84); Sensor Depth: 0.91m; Data Range: 20041002-20050520.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  19. CRED Subsurface Temperature Recorder (STR); PRIA, JAR; Long: -159.97426, Lat: -00.37555 (WGS84); Sensor Depth: 12.80m; Data Range: 20080327-20100403.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  20. CRED Subsurface Temperature Recorder (STR); CNMI, SAI; Long: 145.72288, Lat: 15.23746 (WGS84); Sensor Depth: 7.62m; Data Range: 20050922-20070519.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  1. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.27185, Lat: 23.85682 (WGS84); Sensor Depth: 7.90m; Data Range: 20040918-20051009.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  2. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.88088, Lat: 27.78169 (WGS84); Sensor Depth: 13.72m; Data Range: 20060913-20060922.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  3. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.81591, Lat: 27.85395 (WGS84); Sensor Depth: 0.30m; Data Range: 20090925-20100914.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.17373, Lat: 23.64516 (WGS84); Sensor Depth: 2.13m; Data Range: 20060906-20070930.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  5. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.41908, Lat: -14.23545 (WGS84); Sensor Depth: 9.75m; Data Range: 20080303-20100313.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); CNMI, MAU; Long: 145.23207, Lat: 20.02910 (WGS84); Sensor Depth: 8.84m; Data Range: 20050913-20070530.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62152, Lat: 00.80650 (WGS84); Sensor Depth: 18.60m; Data Range: 20040121-20060125.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. CRED Subsurface Temperature Recorder (STR); Guam; Long: 144.70392, Lat: 13.24217 (WGS84); Sensor Depth: 5.18m; Data Date Range: 20090410-20110507.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  9. CRED Subsurface Temperature Recorder (STR); CNMI, SAI; Long: 145.78947, Lat: 15.17485 (WGS84); Sensor Depth: 19.20m; Data Range: 20080815-20090419.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); CNMI, ANA; Long: 145.70275, Lat: 16.33293 (WGS84); Sensor Depth: 3.96m; Data Range: 20050923-20070527.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.53975, Lat: 25.38410 (WGS84); Sensor Depth: 1.52m; Data Range: 20060909-20080919.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); CNMI, FDP; Long: 144.90023, Lat: 20.53725 (WGS84); Sensor Depth: 31.70m; Data Range: 20070603-20090428.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); MHI, LAN; Long: -156.87525, Lat: 20.74163 (WGS84); Sensor Depth: 11.58m; Data Range: 20081020-20101022.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.86298, Lat: 27.79097 (WGS84); Sensor Depth: 11.60m; Data Range: 20100520-20100915.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  15. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.77935, Lat: 27.80267 (WGS84); Sensor Depth: 1.52m; Data Range: 20080924-20100914.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  16. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62216, Lat: 00.82351 (WGS84); Sensor Depth: 18.90m; Data Range: 20040122-20060226.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  17. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.62662, Lat: -14.18175 (WGS84); Sensor Depth: 9.80m; Data Range: 20040207-20060226.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  18. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.66913, Lat: 25.41957 (WGS84); Sensor Depth: 11.58m; Data Range: 20080918-20090615.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  19. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.34437, Lat: 28.21823 (WGS84); Sensor Depth: 9.14m; Data Range: 20050701-20060915.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  20. CRED Subsurface Temperature Recorder (STR); PRIA, PAL; Long: -162.06183, Lat: 05.88278 (WGS84); Sensor Depth: 4.26m; Data Range: 20060324-20080330.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  1. CRED Subsurface Temperature Recorder (STR); PRIA, WAK; Long: 166.63805, Lat: 19.30092 (WGS84); Sensor Depth: 1.22m; Data Range: 20070505-20090324.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  2. CRED Subsurface Temperature Recorder (STR); PRIA, WAK; Long: 166.62868, Lat: 19.28032 (WGS84); Sensor Depth: 12.50m; Data Range: 20051020-20070428.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  3. CRED Subsurface Temperature Recorder (STR); PRIA, WAK; Long: 166.62210, Lat: 19.30740 (WGS84); Sensor Depth: 3.05m; Data Range: 20070505-20090307.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. NOAA Climate Data Record (CDR) of Reflectance and Brightness Temperatures from AVHRR Pathfinder Atmospheres - Extended (PATMOS-x), Version 5.3

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This NOAA Climate Data Record (CDR) of AVHRR reflectance and brightness temperatures was produced by the University of Wisconsin using the AVHRR Pathfinder...

  5. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.51372, Lat: 25.36697 (WGS84); Sensor Depth: 4.27m; Data Range: 20040921-20060909.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.64291, Lat: 25.47130 (WGS84); Sensor Depth: 14.33m; Data Range: 20060908-20080905.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.63382, Lat: 25.44643 (WGS84); Sensor Depth: 8.53m; Data Range: 20040924-20060907.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.53972, Lat: 25.38417 (WGS84); Sensor Depth: 1.50m; Data Range: 20030720-20040920.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  9. CRED Subsurface Temperature Recorder (STR); NWHI, MAR; Long: -170.51376, Lat: 25.36694 (WGS84); Sensor Depth: 4.27m; Data Range: 20060909-20080919.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); CNMI, ZEA; Long: 145.85335, Lat: 16.89749 (WGS84); Sensor Depth: 24.68m; Data Range: 20070526-20090505.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); PRIA, JAR; Long: -159.97228, Lat: -00.37500 (WGS84); Sensor Depth: 30.70m; Data Range: 20060320-20080328.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.36787, Lat: 28.27767 (WGS84); Sensor Depth: 0.91m; Data Range: 20041012-20060915.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.16685, Lat: 23.73815 (WGS84); Sensor Depth: 2.13m; Data Range: 20060906-20081008.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. CRED Subsurface Temperature Recorder (STR); AMSM, ROS; Long: -168.15343, Lat: -14.53775 (WGS84); Sensor Depth: 2.10m; Data Range: 20060307-20080311.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  15. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.58458, Lat: 20.79070 (WGS84); Sensor Depth: 14.60m; Data Range: 20050806-20070402.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  16. CRED Subsurface Temperature Recorder (STR); MHI, MAI; Long: -156.15120, Lat: 20.86456 (WGS84); Sensor Depth: 14.63m; Data Range: 20081018-20101016.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  17. CRED Subsurface Temperature Recorder (STR); MHI, LAN; Long: -156.83701, Lat: 20.87187 (WGS84); Sensor Depth: 13.10m; Data Range: 20060805-20081019.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  18. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.44661, Lat: -14.25073 (WGS84); Sensor Depth: 6.10m; Data Range: 20060303-20080302.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  19. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.50891, Lat: -14.24402 (WGS84); Sensor Depth: 14.33m; Data Range: 20080301-20081119.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  20. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.41906, Lat: -14.23544 (WGS84); Sensor Depth: 10.97m; Data Range: 20060303-20080302.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  1. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.50890, Lat: -14.24409 (WGS84); Sensor Depth: 15.50m; Data Range: 20060304-20080301.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  2. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.44669, Lat: -14.25079 (WGS84); Sensor Depth: 6.10m; Data Range: 20040204-20060303.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  3. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.50881, Lat: -14.24395 (WGS84); Sensor Depth: 14.30m; Data Range: 20050808-20060304.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. CRED Subsurface Temperature Recorder (STR); AMSM, TAU; Long: -169.44103, Lat: -14.21192 (WGS84); Sensor Depth: 12.80m; Data Range: 20080305-20100312.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  5. CRED Subsurface Temperature Recorder (STR); CNMI, ANA; Long: 145.70271, Lat: 16.33289 (WGS84); Sensor Depth: 3.65m; Data Range: 20070527-20090506.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.78339, Lat: 27.78197 (WGS84); Sensor Depth: 22.86m; Data Range: 20070805-20080924.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); CNMI, MAU; Long: 145.22985, Lat: 20.02314 (WGS84); Sensor Depth: 9.75m; Data Range: 20050911-20070531.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. CRED Subsurface Temperature Recorder (STR); AMSM, OFU; Long: -169.65171, Lat: -14.18072 (WGS84); Sensor Depth: 30.78m; Data Range: 20080228-20100311.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  9. CRED Subsurface Temperature Recorder (STR); PRIA, KIN; Long: -162.38180, Lat: 06.42888 (WGS84); Sensor Depth: 5.18m; Data Range: 20080407-20100415.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); MHI, HAW; Long: -155.50222, Lat: 19.13291 (WGS84); Sensor Depth: 14.90m; Data Range: 20060816-20081031.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); MHI, LAN; Long: -156.96869, Lat: 20.73729 (WGS84); Sensor Depth: 8.23m; Data Range: 20050804-20060806.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); NWHI, NEC; Long: -164.69775, Lat: 23.57152 (WGS84); Sensor Depth: 17.07m; Data Range: 20050414-20060904.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.83134, Lat: 27.89797 (WGS84); Sensor Depth: 1.52m; Data Range: 20060915-20080923.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.89428, Lat: 27.91183 (WGS84); Sensor Depth: 2.50m; Data Range: 20020926-20030729.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  15. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.32340, Lat: 28.24453 (WGS84); Sensor Depth: 0.91m; Data Range: 20041003-20060915.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  16. CRED Subsurface Temperature Recorder (STR); NWHI, LAY; Long: -171.73891, Lat: 25.77957 (WGS84); Sensor Depth: 1.22m; Data Range: 20060911-20070411.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  17. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.36784, Lat: 28.27764 (WGS84); Sensor Depth: 1.22m; Data Range: 20060915-20080925.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  18. CRED Subsurface Temperature Recorder (STR); NWHI, KUR; Long: -178.32575, Lat: 28.38175 (WGS84); Sensor Depth: 12.50m; Data Range: 20090915-20100519.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  19. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.21967, Lat: 23.86611 (WGS84); Sensor Depth: 2.00m; Data Range: 20020912-20030714.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  20. CRED Subsurface Temperature Recorder (STR); NWHI, MID; Long: -177.37495, Lat: 28.19637 (WGS84); Sensor Depth: 14.33m; Data Range: 20080925-20091009.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  1. CRED Subsurface Temperature Recorder (STR); NWHI, LIS; Long: -173.96097, Lat: 26.06337 (WGS84); Sensor Depth: 0.61m; Data Range: 20060925-20081005.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  2. CRED Subsurface Temperature Recorder (STR); NWHI, LAY; Long: -171.74250, Lat: 25.77240 (WGS84); Sensor Depth: 3.30m; Data Range: 20050613-20060910.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  3. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.78082, Lat: 27.95763 (WGS84); Sensor Depth: 1.22m; Data Range: 20080923-20100916.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  4. CRED Subsurface Temperature Recorder (STR); CNMI, SAR; Long: 145.76794, Lat: 16.71069 (WGS84); Sensor Depth: 5.79m; Data Range: 20070525-20080119.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  5. CRED Subsurface Temperature Recorder (STR); PRIA, JOH; Long: -169.55502, Lat: 16.71490 (WGS84); Sensor Depth: 3.04m; Data Range: 20060121-20080127.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  6. CRED Subsurface Temperature Recorder (STR); CNMI, MAU; Long: 145.20731, Lat: 20.01769 (WGS84); Sensor Depth: 10.05m; Data Range: 20070531-20090430.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  7. CRED Subsurface Temperature Recorder (STR); PRIA, HOW; Long: -176.62134, Lat: 00.80661 (WGS84); Sensor Depth: 3.05m; Data Range: 20080207-20100203.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  8. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.86492, Lat: 27.94435 (WGS84); Sensor Depth: 35.05m; Data Range: 20060923-20070726.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  9. CRED Subsurface Temperature Recorder (STR); NWHI, PHR; Long: -175.89428, Lat: 27.91178 (WGS84); Sensor Depth: 2.40m; Data Range: 20030730-20040930.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  10. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.17377, Lat: 23.64516 (WGS84); Sensor Depth: 2.13m; Data Range: 20070930-20080915.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  11. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.27510, Lat: 23.85623 (WGS84); Sensor Depth: 7.62m; Data Range: 20080915-20091009.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  12. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.17967, Lat: 23.63883 (WGS84); Sensor Depth: 10.67m; Data Range: 20070930-20080915.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  13. CRED Subsurface Temperature Recorder (STR); NWHI, FFS; Long: -166.16685, Lat: 23.73815 (WGS84); Sensor Depth: 2.00m; Data Range: 20030717-20040916.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from Coral Reef Ecosystem Division (CRED), NOAA Pacific Islands Fisheries Science Center (PIFSC) Subsurface Temperature Recorders (STR) provide a time series of...

  14. Munchausen Syndrome by Proxy: A Clinical Vignette

    Science.gov (United States)

    Zylstra, Robert G.; Miller, Karl E.; Stephens, Walter E.

    2000-01-01

    Munchausen syndrome by proxy is the act of one person fabricating or inducing an illness in another to meet his or her own emotional needs through the treatment process. The diagnosis is poorly understood and controversial. We report here the case of a 6-year-old boy who presented with possible pneumonia, nausea, vomiting, and diarrhea and whose mother was suspected of Munchausen syndrome by proxy. PMID:15014581

  15. PENGELOLAAN JARINGAN INTERNET DENGAN PROXY WINGATE

    Directory of Open Access Journals (Sweden)

    Titin Winarti

    2005-01-01

    Full Text Available Proxy adalah bagian dari protokol yang berfungsi sebagai link untuk host tunggal atau sebagai link untuk beberapa host antarajaringan dan jaringan lain. Proxy wingate adalah software yang digunakan untuk berbagi koneksi internet melalui satu alamat IPyang terintegrasi ke internet.

  16. Reconstructing Holocene palaeo-environmental conditions in the Baltic: A multi-proxy comparison from the Little Belt (IODP Expedition 347, Site M0059)

    Science.gov (United States)

    Kotthoff, Ulrich; Andrén, Elinor; Andrén, Thomas; Ash, Jeanine; Bauersachs, Thorsten; Fanget, Anne-Sophie; Granoszewski, Wojciech; Groeneveld, Jeroen; Krupinski, Nadine; Peyron, Odile; Slomp, Caroline; Stepanova, Anna; Warnock, Jonathan; van Helmond, Niels; Expedition 347 Science Party

    2016-04-01

    Some of the largest marine environmental impacts from ongoing global climate change are occurring in continental shelf seas and enclosed basins, including severe oxygen depletion, intensifying stratification, and increasing temperatures. In order to predict future changes in water mass conditions, it is essential to reconstruct how these conditions have changed in the past against the background of climate changes. The brackish Baltic Sea is one of the largest semi-enclosed basins worldwide, and its sediment records provide a unique opportunity to analyse palaeo-environmental and climate change in central and northern Europe. IODP Expedition 347 recovered an exceptional set of sediment cores from the Baltic Sea which allow high-resolution reconstructions in unprecedented quality. We present a comparison of commonly-used proxies to reconstruct palaeoecosystems, -temperatures, and -salinity from IODP Site M0059 in the Little Belt over the past ˜8000 years. Our aim is to reconstruct the development of the terrestrial and marine ecosystems in the research area and the related environmental conditions, and to identify potential limitations of individual proxies. The age model for Site M0059 is based on 14Cdating, biostratigraphic correlation with neighbouring terrestrial pollen records, and sediment stratigraphy. Sedimentary organic carbon content and the bulk elemental composition have been measured, and can be used to determine the depositional environment and degree of oxygen depletion (e.g., Mo, Corg/Ptot). Pollen is used as proxy for vegetation development in the hinterland of the southern Baltic Sea and as a land/air-temperature proxy. Comparison with dinoflagellate cysts, insect remains, and green algae remains from the same samples provides a direct land-sea comparison. The application of the modern analogues technique to pollen assemblages has previously yielded precise results for late Pleistocene and Holocene datasets, including specific information on

  17. Web proxy auto discovery for the WLCG

    CERN Document Server

    Dykstra, D; Blumenfeld, B; De Salvo, A; Dewhurst, A; Verguilov, V

    2017-01-01

    All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids regis...

  18. Geochemistry and Temperatures Recorded by Zircon During the Final Stages of the Youngest Toba Tuff Magma Chamber, Sumatra, Indonesia

    Science.gov (United States)

    Gaither, T.; Reid, M. R.; Vazquez, J. A.

    2009-12-01

    The ~74 ka eruption of the Youngest Toba Tuff (YTT) in Sumatra, Indonesia, was one of the largest single volcanic eruptions in geologic history, on par with other voluminous silicic eruptions such as the Huckleberry Ridge Tuff of Yellowstone and the Bishop Tuff of Long Valley, California. We are exploring how zircon and other accessory mineral phases record compositional and thermal changes that occurred in the YTT magma, and the important clues these crystal scale records hold for magma chamber dynamics and processes that lead up to supervolcano eruptions. In this study, we report trace element (REE, U, Th, Ti, and Hf) characteristics, Ti-in-zircon crystallization temperatures, and apparent REE partition coefficients obtained for YTT zircon rims. Twenty-nine zircons from pumices with a compositional range of 70-76 wt% SiO2 were analyzed on the UCLA Cameca ims 1270 ion microprobe. The grains were mounted so that only the outermost ~1.5 microns of the crystals were analyzed. Median Zr/Hf ratios of 34 to 38 characterize zircons from the pumices; the high silica rhyolite grains have lower Zr/Hf. Chondrite-normalized REE patterns are strongly LREE-depleted. Positive Ce anomalies are large (Ce/Ce* ranges up to 88) and Eu/Eu* varies by a factor of four (0.05 to 0.21). Eu/Eu*, Nd/Yb, and Th/U decrease with decreasing Zr/Hf, showing that the variation in zircon rim compositions may be related by co-precipitation of feldspar and allanite along with zircon. Titanium contents also decrease with decreasing Zr/Hf, suggesting that the chemical differences could be related to temperature changes. REE partition coefficients calculated from zircon rim compositions and pumice glass compositions give a good fit to a lattice strain model. They are also quite similar to the partition coefficients of Sano et al. (2002) which have been shown to be successful at reproducing melt compositions in other settings. Temperatures of crystallization calculated using the Ti

  19. Micropalaeontological proxies for understanding palaeoclimate

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.

    rise, climate change are all consequences of increased emission of green house gases. Such environmental problems are economically taxing to every economy. Thus prediction of future climates on the decadal and centennial time-scales helps... in the right management and distribution of resources. Predictive models are derived on the basis of large datasets on past climates, spanning thousands of years, i.e. well beyond the era of instrumental records which exist just for about 150 years...

  20. A method of separating local and large scale climate signals in coral proxies

    Science.gov (United States)

    Timm, O.; Ruprecht, E.; Pfeiffer, M.; Dullo, W.

    2003-04-01

    Coral proxies in the tropical and subtropical Indian Ocean show markedly different imprints of local climate factors. The oxygen isotopic composition (d18o) reflects a combination of SST and seawater properties. Both are the response to local effects and large scale climate variations in the oceans and the atmosphere, mainly due to air-sea fluxes. Consequently, an important step to large scale climate reconstructions from coral proxies is the separation of the individual local signal and the teleconnection with large scale climate modes such as the El Nino/Southern Oscillation (ENSO). The aim of this study is to present a method capable of extracting the large scale climate signal recorded in corals. Using multiple linear regression (MLR) techniques we first analyse the partial effects of local SST and precipitation minus evaporation on the coral d18o proxies. In a second step multivariate statistics are applied to the proxies and climate variables in order to distinguish between local signals and large scale variability in the proxies. Three d18o records from the Indian Ocean (Chagos, La Reunion, Seychelles) and the ENSO signal are used as an example demonstration. The method is also applied to Carribean corals (Guadeloupe). Preliminary results for the variability of these proxies and their relation to the North Atlantic Oscillation are given.

  1. The isotopic composition of valves and organic tissue of diatoms grown in steady state cultures under varying conditions of temperature, light and nutrients. Implications for the interpretation of oxygen isotopes from sedimentary biogenic opal as proxies of environmental variations

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, K.

    2006-05-15

    The oxygen isotopes of diatomaceous silica from marine and freshwater sediments are frequently used as indicators of the palaeotemperature development, particularly in cases where calcareous microfossils are rare or absent. With regard to terrestrial waters it is unknown whether or not palaeotemperature scale can be used in a limnic ecosystem. Due to the fact that the seasonal variations in lakes are larger than in oceans, specific problems arise when working with freshwater sediments. Thus, an understanding of the contribution of the various factors (e.g. temperature, light nutrients, competition) influencing the formation of isotope signals in biogenic opal is a prerequisite for the accurate interpretation of environmental processes. Since it is impossible to examine the influence of a single parameter under natural ecosystem conditions due to permanent changes of the environment, laboratory experiments with single diatom species are needed. Therefore, the aim of this study was to investigate the correlation between the oxygen isotope variations in biogenic opal and different environmental parameters using steady state cultures with diatoms. It should be examined whether or not the different diatom species grown under identical conditions show equal oxygen isotope ratios (species relationship), if variations of the water temperature induce variations of the oxygen isotope ratio (relationship with temperature), variable parameters such as light intensity and nitrate concentration influence the isotope ratio, and if vital effects (e.g. growth rate) lead to variations of the oxygen isotope ratio. (orig.)

  2. Modelling the Diel Vertical Movement of Swordfish (Xiphias gladius Linnaeus, 1758 Based on Temperature and Depth Recorder Data

    Directory of Open Access Journals (Sweden)

    Bram Setyadji

    2016-03-01

    Full Text Available Understanding the vertical distribution of large pelagic fish, swordfish in particular, could improve our knowledge on its fisheries strategy, management and resource conservation. However the methods often require expensive tools and resources, which probably most scientists from the development countries couldn’t afford. Thus developing model on the diel vertical movement behavior of swordfish using number of hook between float (HBF and complete-set temperature and depth recorder (TDR data could be an alternative. In general context, capture depth distributions are a good indicator of the natural depth distribution of the fish if the entire depth range of the species is targeted by longline gear. The proposed sinusoidal model suggested that swordfish showed a diel pattern in depth distribution, marked by remained in the surface and mixed layer waters at night and dived into deeper waters during the day. Keywords: swordfish, behavior, HBF, TDR, sinusoidal model

  3. Sea Surface Temperature Records Using Sr/Ca Ratios in a Siderastrea siderea Coral from SE Cuba

    Science.gov (United States)

    Fargher, H. A.; Hughen, K. A.; Ossolinski, J. E.; Bretos, F.; Siciliano, D.; Gonzalez, P.

    2015-12-01

    Sea surface temperature (SST) variability from Cuba remains relatively unknown compared to the rest of the Caribbean. Cuba sits near an inflection point in the spatial pattern of SST from the North Atlantic Oscillation (NAO), and long SST records from the region could reveal changes in the influence of this climate system through time. A Siderastrea siderea coral from the Jardínes de la Reina in southern Cuba was drilled to obtain a 220 year long archive of environmental change. The genus Siderastrea has not been extensively studied as an SST archive, yet Sr/Ca ratios in the Cuban core show a clear seasonal signal and strong correlation to instrumental SST data (r2 = 0.86 and 0.36 for monthly and interannual (winter season) timescales, respectively). Annual growth rates (linear extension) of the coral are observed to have a minor influence on Sr/Ca variability, but do not show a direct correlation to SST on timescales from annual to multidecadal. Sr/Ca measurements from the Cuban coral are used to reconstruct monthly and seasonal (winter, summer) SST extending back more than two centuries. Wintertime SST in southern Cuba is compared to other coral Sr/Ca records of winter-season SST from locations sensitive to the NAO in order to investigate the stationarity of the NAO SST 'fingerprint' through time.

  4. The impact of inter-annual variability of annual cycle on long-term memory in long historical temperature records

    Science.gov (United States)

    Deng, Qimin; Fu, Zuntao

    2017-04-01

    Changes in the estimation of long-term correlation induced by inter-annual variability of annual cycle have been investigated by means of detrended fluctuation analysis (DFA). In a consequence of the intrinsic nonlinearity of the climate system, the annual cycle suffers from both amplitude and phase fluctuations. How does this changing annual cycle affect the fluctuation of temperature anomalies? A recently developed adaptive data analysis tool, the Nonlinear Mode Decomposition (NMD), is used to extract and remove time-varying annual cycle. We compared the differences of the long-term correlation calculated by removing different annual cycle, time-varying and stationary. The study was based on long historical temperature records around the North Atlantic Ocean. The traditional climatology annual cycle which lack characteristic of inter-annual fluctuation would lead to: (1) the estimation of Hurst exponent (2) how to choose scaling range and (3) the goodness of fit. Especially removing steady climatology annual cycle would introduce an artificial crossover around one-year period in the DFA curve. The conclusion is verified by generating deterministic time series through Monte Carlo simulations.

  5. Climate in Sweden during the past millennium - Evidence from proxy data, instrumental data and model simulations

    Energy Technology Data Exchange (ETDEWEB)

    Moberg, Anders; Gouirand, Isabelle; Schoning, Kristian; Wohlfarth, Barbara [Stockholm Univ. (Sweden). Dept. of Physical Geography and Quaternary Geology; Kjellstroem, Erik; Rummukainen, Markku [Swedish Meteorological and Hydrological Inst., Norrkoeping (Sweden). Rossby Centre; Jong, Rixt de [Lund Univ. (Sweden). Dept. of Quaternary Geology; Linderholm, Hans [Goeteborg Univ. (Sweden). Dept. of Earth Sciences; Zorita, Eduardo [GKSS Research Centre, Geesthacht (Germany)

    2006-12-15

    Knowledge about climatic variations is essential for SKB in its safety assessments of a geological repository for spent nuclear waste. There is therefore a need for information about possible future climatic variations under a range of possible climatic states. However, predictions of future climate in any deterministic sense are still beyond our reach. We can, nevertheless, try to estimate the magnitude of future climate variability and change due to natural forcing factors, by means of inferences drawn from natural climate variability in the past. Indeed, the climate of the future will be shaped by the sum of natural and anthropogenic climate forcing, as well as the internal climate variability. The aim here is to review and analyse the knowledge about Swedish climate variability, essentially during the past millennium. Available climate proxy data and long instrumental records provide empirical information on past climatic changes. We also demonstrate how climate modelling can be used to extend such knowledge. We use output from a global climate model driven with reconstructed radiative forcings (solar, volcanic and greenhouse gas forcing), to provide boundary conditions for a regional climate model. The regional model provides more details of the climate than the global model, and we develop a simulated climate history for Sweden that is complete in time and space and physically consistent. We use output from a regional model simulation for long periods in the last millennium, to study annual mean temperature, precipitation and runoff for the northern and southern parts of Sweden. The simulated data are used to place corresponding instrumental records for the 20th century into a plausible historical perspective. We also use output from the regional model to study how the frequency distribution of the daily temperature, precipitation, runoff and evaporation at Forsmark and Oskarshamn could have varied between unusually warm and cold 30-year periods during the

  6. Global and hemispheric temperature reconstruction from glacier length fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Leclercq, Paul Willem; Oerlemans, Johannes [Universiteit Utrecht, IMAU, Utrecht (Netherlands)

    2012-03-15

    Temperature reconstructions for recent centuries provide a historical context for the warming over the twentieth century. We reconstruct annual averaged surface temperatures of the past 400 years on hemispherical and global scale from glacier length fluctuations. We use the glacier length records of 308 glaciers. The reconstruction is a temperature proxy with decadal resolution that is completely independent of other temperature records. Temperatures are derived from glacier length changes using a linear response equation and an analytical glacier model that is calibrated on numerical model results. The global and hemispherical temperatures reconstructed from glacier length fluctuations are in good agreement with the instrumental record of the last century. Furthermore our results agree with existing multi-proxy reconstructions of temperature in the pre-instrumental period. The temperature record obtained from glacier fluctuations confirms the pronounced warming of the twentieth century, giving a global cumulative warming of 0.94 {+-} 0.31 K over the period 1830-2000 and a cumulative warming of 0.84 {+-} 0.35 K over the period 1600-2000. (orig.)

  7. A statistical proxy for sulphuric acid concentration

    Directory of Open Access Journals (Sweden)

    S. Mikkonen

    2011-11-01

    Full Text Available Gaseous sulphuric acid is a key precursor for new particle formation in the atmosphere. Previous experimental studies have confirmed a strong correlation between the number concentrations of freshly formed particles and the ambient concentrations of sulphuric acid. This study evaluates a body of experimental gas phase sulphuric acid concentrations, as measured by Chemical Ionization Mass Spectrometry (CIMS during six intensive measurement campaigns and one long-term observational period. The campaign datasets were measured in Hyytiälä, Finland, in 2003 and 2007, in San Pietro Capofiume, Italy, in 2009, in Melpitz, Germany, in 2008, in Atlanta, Georgia, USA, in 2002, and in Niwot Ridge, Colorado, USA, in 2007. The long term data were obtained in Hohenpeissenberg, Germany, during 1998 to 2000. The measured time series were used to construct proximity measures ("proxies" for sulphuric acid concentration by using statistical analysis methods. The objective of this study is to find a proxy for sulfuric acid that is valid in as many different atmospheric environments as possible. Our most accurate and universal formulation of the sulphuric acid concentration proxy uses global solar radiation, SO2 concentration, condensation sink and relative humidity as predictor variables, yielding a correlation measure (R of 0.87 between observed concentration and the proxy predictions. Interestingly, the role of the condensation sink in the proxy was only minor, since similarly accurate proxies could be constructed with global solar radiation and SO2 concentration alone. This could be attributed to SO2 being an indicator for anthropogenic pollution, including particulate and gaseous emissions which represent sinks for the OH radical that, in turn, is needed for the formation of sulphuric acid.

  8. Assessing paleo-biodiversity using low proxy influx.

    Directory of Open Access Journals (Sweden)

    Olivier Blarquez

    Full Text Available We developed an algorithm to improve richness assessment based on paleoecological series, considering sample features such as their temporal resolutions or their volumes. Our new method can be applied to both high- and low-count size proxies, i.e. pollen and plant macroremain records, respectively. While pollen generally abounds in sediments, plant macroremains are generally rare, thus leading to difficulties to compute paleo-biodiversity indices. Our approach uses resampled macroremain influxes that enable the computation of the rarefaction index for the low influx records. The raw counts are resampled to a constant resolution and sample volume by interpolating initial sample ages at a constant time interval using the age∼depth model. Then, the contribution of initial counts and volume to each interpolated sample is determined by calculating a proportion matrix that is in turn used to obtain regularly spaced time series of pollen and macroremain influx. We applied this algorithm to sedimentary data from a subalpine lake situated in the European Alps. The reconstructed total floristic richness at the study site increased gradually when both pollen and macroremain records indicated a decrease in relative abundances of shrubs and an increase in trees from 11,000 to 7,000 cal BP. This points to an ecosystem change that favored trees against shrubs, whereas herb abundance remained stable. Since 6,000 cal BP, local richness decreased based on plant macroremains, while pollen-based richness was stable. The reconstructed richness and evenness are interrelated confirming the difficulty to distinguish these two aspects for the studies in paleo-biodiversity. The present study shows that low-influx bio-proxy records (here macroremains can be used to reconstruct stand diversity and address ecological issues. These developments on macroremain and pollen records may contribute to bridge the gap between paleoecology and biodiversity studies.

  9. Assessing paleo-biodiversity using low proxy influx.

    Science.gov (United States)

    Blarquez, Olivier; Finsinger, Walter; Carcaillet, Christopher

    2013-01-01

    We developed an algorithm to improve richness assessment based on paleoecological series, considering sample features such as their temporal resolutions or their volumes. Our new method can be applied to both high- and low-count size proxies, i.e. pollen and plant macroremain records, respectively. While pollen generally abounds in sediments, plant macroremains are generally rare, thus leading to difficulties to compute paleo-biodiversity indices. Our approach uses resampled macroremain influxes that enable the computation of the rarefaction index for the low influx records. The raw counts are resampled to a constant resolution and sample volume by interpolating initial sample ages at a constant time interval using the age∼depth model. Then, the contribution of initial counts and volume to each interpolated sample is determined by calculating a proportion matrix that is in turn used to obtain regularly spaced time series of pollen and macroremain influx. We applied this algorithm to sedimentary data from a subalpine lake situated in the European Alps. The reconstructed total floristic richness at the study site increased gradually when both pollen and macroremain records indicated a decrease in relative abundances of shrubs and an increase in trees from 11,000 to 7,000 cal BP. This points to an ecosystem change that favored trees against shrubs, whereas herb abundance remained stable. Since 6,000 cal BP, local richness decreased based on plant macroremains, while pollen-based richness was stable. The reconstructed richness and evenness are interrelated confirming the difficulty to distinguish these two aspects for the studies in paleo-biodiversity. The present study shows that low-influx bio-proxy records (here macroremains) can be used to reconstruct stand diversity and address ecological issues. These developments on macroremain and pollen records may contribute to bridge the gap between paleoecology and biodiversity studies.

  10. Web Proxy Auto Discovery for the WLCG

    Science.gov (United States)

    Dykstra, D.; Blomer, J.; Blumenfeld, B.; De Salvo, A.; Dewhurst, A.; Verguilov, V.

    2017-10-01

    All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment’s jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids registered in the ATLAS Grid Information System (AGIS) and CMS SITECONF files, cross-checked with squids registered by sites in the Grid Configuration Database (GOCDB) and the OSG Information Management (OIM) system, and combined with some exceptions manually configured by people from ATLAS and CMS who operate WLCG Squid monitoring. WPAD servers at CERN respond to http requests from grid nodes all over the world with a PAC file that lists available web proxies, based on IP addresses matched from a database that contains the IP address ranges registered to organizations. Large grid sites are encouraged to supply their own WPAD web servers for more flexibility, to avoid being affected by short term long distance network outages, and to offload the WLCG WPAD servers at CERN. The CERN WPAD servers additionally support requests from jobs running at non-grid sites (particularly for LHC@Home) which they direct to the nearest publicly accessible web proxy servers. The responses

  11. Applying a family systems lens to proxy decision making in clinical practice and research.

    Science.gov (United States)

    Rolland, John S; Emanuel, Linda L; Torke, Alexia M

    2017-03-01

    When patients are incapacitated and face serious illness, family members must make medical decisions for the patient. Medical decision sciences give only modest attention to the relationships among patients and their family members, including impact that these relationships have on the decision-making process. A review of the literature reveals little effort to systematically apply a theoretical framework to the role of family interactions in proxy decision making. A family systems perspective can provide a useful lens through which to understand the dynamics of proxy decision making. This article considers the mutual impact of family systems on the processes and outcomes of proxy decision making. The article first reviews medical decision science's evolution and focus on proxy decision making and then reviews a family systems approach, giving particular attention to Rolland's Family Systems Illness Model. A case illustrates how clinical practice and how research would benefit from bringing family systems thinking to proxy decisions. We recommend including a family systems approach in medical decision science research and clinical practices around proxy decisions making. We propose that clinical decisions could be less conflicted and less emotionally troubling for families and clinicians if family systems approaches were included. This perspective opens new directions for research and novel approaches to clinical care. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  12. Timing of strain localization in high-pressure low-temperature shear zones: The argon isotopic record

    Science.gov (United States)

    Laurent, Valentin; Scaillet, Stéphane; Jolivet, Laurent; Augier, Romain

    2017-04-01

    The complex interplay between rheology, temperature and deformation profoundly influences how crustal-scale shear zones form and then evolve across a deforming lithosphere. Understanding early exhumation processes in subduction zones requires quantitative age constraints on the timing of strain localization within high-pressure shear zones. Using both the in situ laser ablation and conventional step-heating 40Ar/39Ar dating (on phengite single grains and populations) methods, this study aims at quantifying the duration of ductile deformation and the timing of strain localization within HP-LT shear zones of the Cycladic Blueschist Unit (CBU, Greece). The rate of this progressive strain localization is unknown, and in general, poorly known in similar geological contexts. Critical to retrieve realistic estimates of rates of strain localization during exhumation, dense 40Ar/39Ar age transects were sampled along shear zones recently identified on Syros and Sifnos islands. There, field observations suggest that deformation progressively localized downward in the CBU during exhumation. In parallel, these shear zones are characterized by different degrees of retrogression from blueschist-facies to greenschist-facies P-T conditions overprinting eclogite-facies record throughout the CBU. Results show straightforward correlations between the degree of retrogression, the finite strain intensity and 40Ar/39Ar ages; the most ductilely deformed and retrograded rocks yielded the youngest 40Ar/39Ar ages. The possible effects of strain localization during exhumation on the record of the argon isotopic system in HP-LT shear zones are addressed. Our results show that strain has localized in shear zones over a 30 Ma long period and that individual shear zones evolve during 7-15 Ma. We also discuss these results at small-scale to see whether deformation and fluid circulations, channelled within shear bands, can homogenize chemical compositions and reset the 40Ar/39Ar isotopic record

  13. Climate inferences between paleontological, geochemical, and geophysical proxies in Late Pleistocene lacustrine sediments from Summer Lake, Oregon, western Great Basin

    Science.gov (United States)

    Heaton, Eric; Thompson, Greg; Negrini, Rob; Wigand, Peter

    2016-04-01

    Paleontological, geochemical, and geophysical data from western Great Basin pluvial Summer Lake, Oregon have established a high resolution paleoclimate record during the late Pleistocene Mono Lake Excursion (~34.75 ka), Dansgaard-Oeschger interstadials 6-8, and the end of Heinrich Even 4 (~38 ka). Proxies of grain-size, magnetic susceptibility, carbon/nitrogen ratio, ostracode analysis and palynology from a depocenter core show new results with improved age control regarding high amplitude, high frequency changes in lake level, lake temperature, and regional precipitation and temperature which correspond directly with colder/warmer and respectively drier/wetter climates as documented with Northern Atlantic Greenland ice core data. Results from geophysical and geochemical analysis, and the presence of ostracode Cytherissa lacustris consistently demonstrate the correspondence of low lake conditions and colder water temperatures during Dansgaard-Oeschger stadials and the Mono Lake Excursion. The opposite holds true during interstadials. Smaller grain size, increases in carbon/nitrogen ratio and consistent absence of C. lacustris suggest periods of increased discharge into the lake, increased lake level, and warmer water temperatures. Warmer/wetter climate conditions are confirmed during interstadials 7 and 8 from pollen analysis. Existence of Atriplex, Rosaceae, Chrysothamnus and Ambrosia, and pollen ratios of Juniperus/Dip Pinus and (Rosaceae+Atriplex+Poaceae+Chrysothamnus+Ambrosia)/(Pinus+Picea+T. mertensiana+Sarcobatus) suggest warmer/wetter semi-arid woodland conditions during interstadials 7 and 8. This contrasts with absences in these pollens and pollen ratios indicating colder/drier continental montane woodland conditions during stadials and the Mono Lake Excursion. Increases in Juniper/Dip Pinus ratio suggest a warmer/wetter climate during interstadial 6 however additional proxies do not demonstrate comparative warmer/wetter climate, deeper lake level or

  14. Toward all weather, long record, and real-time land surface temperature retrievals from microwave satellite observations

    Science.gov (United States)

    Jimenez, Carlos; Prigent, Catherine; Aires, Filipe; Ermida, Sofia

    2017-04-01

    The land surface temperature can be estimated from satellite passive microwave observations, with limited contamination from the clouds as compared to the infrared satellite retrievals. With ˜60% cloud cover in average over the globe, there is a need for "all weather," long record, and real-time estimates of land surface temperature (Ts) from microwaves. A simple yet accurate methodology is developed to derive the land surface temperature from microwave conical scanner observations, with the help of pre-calculated land surface microwave emissivities. The method is applied to the Special Sensor Microwave/Imagers (SSM/I) and the Earth observation satellite (EOS) Advanced Microwave Scanning Radiometer (AMSR-E) observations?, regardless of the cloud cover. The SSM/I results are compared to infrared estimates from International Satellite Cloud Climatology Project (ISCCP) and from Advanced Along Track Scanning Radiometer (AATSR), under clear-sky conditions. Limited biases are observed (˜0.5 K for both comparisons) with a root-mean-square difference (RMSD) of ˜5 K, to be compared to the RMSE of ˜3.5 K between ISCCP et AATSR. AMSR-E results are compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) clear-sky estimates. As both instruments are on board the same satellite, this reduces the uncertainty associated to the observations match-up, resulting in a lower RMSD of ˜ 4K. The microwave Ts is compared to in situ Ts time series from a collection of ground stations over a large range of environments. For 22 stations available in the 2003-2004 period, SSM/I Ts agrees very well for stations in vegetated environments (down to RMSD of ˜2.5 K for several stations), but the retrieval methodology encounters difficulties under cold conditions due to the large variability of snow and ice surface emissivities. For 10 stations in the year 2010, AMSR-E presents an all-station mean RMSD of ˜4.0 K with respect tom the ground Ts. Over the same stations, MODIS

  15. Munchausen Syndrome by Proxy: Medical Diagnostic Criteria.

    Science.gov (United States)

    Rosenberg, Donna Andrea

    2003-01-01

    Medical diagnostic criteria for Munchausen Syndrome by Proxy (a persistent fabrication by one individual of illness in another) are presented. Since the strength of the known facts may vary from case to case, diagnostic criteria are given for a definitive diagnosis, a possible diagnosis, an inconclusive determination, and the definitely excluded…

  16. Munchausen Syndrome by Proxy: Evaluation and Treatment.

    Science.gov (United States)

    Parnell, Teresa F.; Day, Deborah O.

    Munchausen Syndrome by Proxy (MSBP) is characterized by a significant caretaker, usually a mother, deliberately inducing and/or falsely reporting illness in a child. The potentially fatal outcome of undetected MSBP makes the understanding of this syndrome gravely important. Early detection and effective intervention can be accomplished through the…

  17. Munchausen Syndrome by Proxy: Social Work's Role.

    Science.gov (United States)

    Mercer, Susan O.; Perdue, Jeanette D.

    1993-01-01

    Describes Munchausen syndrome by proxy, diagnosis used to describe variation of child abuse whereby parent or adult caregiver fabricates medical history or induces symptoms in child, or both, resulting in unnecessary examinations, treatments, hospitalizations, and even death. Reviews assessment procedures, provides case studies, and describes…

  18. The Syndrome of Munchausen by Proxy.

    Science.gov (United States)

    Jones, David P. H.

    1994-01-01

    This editorial introduces two articles on Munchausen by Proxy syndrome (the induction of an appearance or state of physical ill health in a child, by the caretaker, and the child's subsequent presentation to health professionals for diagnosis and/or treatment). The severity of the caretaker's psychological disturbance and the serious effects on…

  19. Improving Internet Archive Service through Proxy Cache.

    Science.gov (United States)

    Yu, Hsiang-Fu; Chen, Yi-Ming; Wang, Shih-Yong; Tseng, Li-Ming

    2003-01-01

    Discusses file transfer protocol (FTP) servers for downloading archives (files with particular file extensions), and the change to HTTP (Hypertext transfer protocol) with increased Web use. Topics include the Archie server; proxy cache servers; and how to improve the hit rate of archives by a combination of caching and better searching mechanisms.…

  20. A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

    Science.gov (United States)

    Morellón, M.; Pérez-Sanz, A.; Corella, J. P.; Büntgen, U.; Catalán, J.; González-Sampériz, P.; González-Trueba, J. J.; López-Sáez, J. A.; Moreno, A.; Pla-Rabes, S.; Saz-Sánchez, M. Á.; Scussolini, P.; Serrano, E.; Steinhilber, F.; Stefanova, V.; Vegas-Vilarrúbia, T.; Valero-Garcés, B.

    2012-03-01

    This paper reviews multi-proxy paleoclimatic reconstructions with robust age-control derived from lacustrine, dendrochronological and geomorphological records and characterizes the main environmental changes that occurred in the Southern Pyrenees during the last millennium. Warmer and relatively arid conditions prevailed during the Medieval Climate Anomaly (MCA, ca. 900-1300 AD), with a significant development of xerophytes and Mediterranean vegetation and limited deciduous tree formations (mesophytes). The Little Ice Age (LIA, 1300-1800 AD) was generally colder and moister, with an expansion of deciduous taxa and cold-adapted montane conifers. Two major phases occurred within this period: (i) a transition MCA-LIA, characterized by fluctuating, moist conditions and relatively cold temperatures (ca. 1300 and 1600 AD); and (ii) a second period, characterized by the coldest and most humid conditions, coinciding with maximum (recent) glacier advances (ca. 1600-1800 AD). Glaciers retreated after the LIA when warmer and more arid conditions dominated, interrupted by a short-living cooling episode during the late 19th to early 20th centuries. Some records suggest a response to solar activity with colder and slightly moister conditions during solar minima. Centennial-scale hydrological fluctuations are in phase with reconstructions of NAO variability, which appears to be one of the main climate mechanisms influencing rainfall variations in the region during the last millennium.

  1. A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

    Directory of Open Access Journals (Sweden)

    M. Morellón

    2012-03-01

    Full Text Available This paper reviews multi-proxy paleoclimatic reconstructions with robust age-control derived from lacustrine, dendrochronological and geomorphological records and characterizes the main environmental changes that occurred in the Southern Pyrenees during the last millennium. Warmer and relatively arid conditions prevailed during the Medieval Climate Anomaly (MCA, ca. 900–1300 AD, with a significant development of xerophytes and Mediterranean vegetation and limited deciduous tree formations (mesophytes. The Little Ice Age (LIA, 1300–1800 AD was generally colder and moister, with an expansion of deciduous taxa and cold-adapted montane conifers. Two major phases occurred within this period: (i a transition MCA–LIA, characterized by fluctuating, moist conditions and relatively cold temperatures (ca. 1300 and 1600 AD; and (ii a second period, characterized by the coldest and most humid conditions, coinciding with maximum (recent glacier advances (ca. 1600–1800 AD. Glaciers retreated after the LIA when warmer and more arid conditions dominated, interrupted by a short-living cooling episode during the late 19th to early 20th centuries. Some records suggest a response to solar activity with colder and slightly moister conditions during solar minima. Centennial-scale hydrological fluctuations are in phase with reconstructions of NAO variability, which appears to be one of the main climate mechanisms influencing rainfall variations in the region during the last millennium.

  2. Arctic and Antarctic Oscillation signatures in tropical coral proxies over the South China Sea

    Energy Technology Data Exchange (ETDEWEB)

    Gong, D.Y. [Beijing Normal Univ. (China). State Key Lab. of Earth Surface Processes and Resource Ecology; Kim, S.J. [Korea Polar Research Inst., Incheon (Korea); Ho, C.H. [Seoul National Univ. (Korea). School of Earth and Environmental Sciences

    2009-07-01

    Arctic Oscillation (AO) and Antarctic Oscillation (AAO) are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr) content, which represents the sea surface temperature (SST). Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1-3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes. (orig.)

  3. Arctic and Antarctic Oscillation signatures in tropical coral proxies over the South China Sea

    Directory of Open Access Journals (Sweden)

    D.-Y. Gong

    2009-05-01

    Full Text Available Arctic Oscillation (AO and Antarctic Oscillation (AAO are the leading modes of atmospheric circulation in mid-high latitudes. Previous studies have revealed that the climatic influences of the two modes are dominant in extra-tropical regions. This study finds that AO and AAO signals are also well recorded in coral proxies in the tropical South China Sea. There are significant interannual signals of AO and AAO in the strontium (Sr content, which represents the sea surface temperature (SST. Among all the seasons, the most significant correlation occurs during winter in both hemispheres: the strongest AO-Sr and AAO-Sr coral correlations occur in January and August, respectively. This study also determined that the Sr content lags behind AO and AAO by 1–3 months. Large-scale anomalies in sea level pressure and horizontal wind at 850 hPa level support the strength of AO/AAO-coral teleconnections. In addition, a comparison with oxygen isotope records from two coral sites in neighboring oceans yields significant AO and AAO signatures with similar time lags. These results help to better understand monsoon climates and their teleconnection to high-latitude climate changes.

  4. A reconstruction of sea surface temperature variability in the southeastern Gulf of Mexico from 1734 to 2008 C.E. using cross-dated Sr/Ca records from the coral Siderastrea siderea

    Science.gov (United States)

    DeLong, Kristine L.; Maupin, Christopher R.; Flannery, Jennifer A.; Quinn, Terrence M.; Shen, CC

    2014-01-01

    This study uses skeletal variations in coral Sr/Ca from three Siderastrea siderea coral colonies within the Dry Tortugas National Park in the southeastern Gulf of Mexico (24°42′N, 82°48′W) to reconstruct monthly sea surface temperature (SST) variations from 1734 to 2008 Common Era (C.E.). Calibration and verification of the replicated coral Sr/Ca-SST reconstruction with local, regional, and historical temperature records reveals that this proxy-temperature relationship is stable back to 1879 C.E. The coral SST reconstruction contains robust interannual (~2.0°C) and multidecadal variability (~1.5°C) for the past 274 years, the latter of which does not covary with the Atlantic Multidecadal Oscillation. Winter SST extremes are more variable than summer SST extremes (±2.2°C versus ±1.6°C, 2σ) suggesting that Loop Current transport in the winter dominates variability on interannual and longer time scales. Summer SST maxima are increasing (+1.0°C for 274 years, σMC = ±0.5°C, 2σ), whereas winter SST minima contain no significant trend. Colder decades (~1.5°C) during the Little Ice Age (LIA) do not coincide with decades of sunspot minima. The coral SST reconstruction contains similar variability to temperature reconstructions from the northern Gulf of Mexico (planktic foraminifer Mg/Ca) and the Caribbean Sea (coral Sr/Ca) suggesting areal reductions in the Western Hemisphere Warm Pool during the LIA. Mean summer coral SST extremes post-1985 C.E. (29.9°C) exceeds the long-term summer average (29.2°C for 1734–2008 C.E.), yet the warming trend after 1985 C.E. (0.04°C for 24 years, σMC = ±0.5, 2σ) is not significant, whereas Caribbean coral Sr/Ca studies contain a warming trend for this interval.

  5. Constructing Proxy Variables to Measure Adult Learners' Time Management Strategies in LMS

    Science.gov (United States)

    Jo, Il-Hyun; Kim, Dongho; Yoon, Meehyun

    2015-01-01

    This study describes the process of constructing proxy variables from recorded log data within a Learning Management System (LMS), which represents adult learners' time management strategies in an online course. Based on previous research, three variables of total login time, login frequency, and regularity of login interval were selected as…

  6. Multi-proxy summer and winter precipitation reconstruction for southern Africa over the last 200 years

    NARCIS (Netherlands)

    Neukom, R.; Nash, D.J.; Endfield, G.H.; Grab, S.W; Grove, C.A.; Kelso, C.; Vogel, C.H.; Zinke, J.

    2014-01-01

    This study presents the first consolidation of palaeoclimate proxy records from multiple archives to develop statistical rainfall reconstructions for southern Africa covering the last two centuries. State-of-the-art ensemble reconstructions reveal multi-decadal rainfall variability in the summer and

  7. Linking coral river runoff proxies with climate variability, hydrology and land-use in Madagascar catchments

    NARCIS (Netherlands)

    Maina, J.; de Moel, H.; Vermaat, J.E.; Bruggemann, J.H.; Guillaume, M.M.M.; Grove, C.A.; Madin, J.S.; Merz-Kraus, R.; Zinke, J.

    2012-01-01

    Understanding the linkages between coastal watersheds and adjacent coral reefs is expected to lead to better coral reef conservation strategies. Our study aims to examine the main predictors of environmental proxies recorded in near shore corals and therefore how linked near shore reefs are to the

  8. How to combine sparse proxy data and coupled climate models

    Science.gov (United States)

    Paul, André; Schäfer-Neth, Christian

    2005-04-01

    We address the problem of reconstructing a global field from proxy data with sparse spatial sampling such as the MARGO (multi-proxy approach for the reconstruction of the glacial ocean surface) SST (sea-surface temperature) and δ18O c (oxygen-18/oxygen-16 isotope ratio preserved in fossil carbonate shells of planktic foraminifera) data. To this end, we propose to `assimilate' these data into coupled climate models by adjusting some of their parameters and optimizing the fit. In particular, we suggest to combine a forward model and an objective function that quantifies the misfit to the data. Because of their computational efficiency, earth system models of intermediate complexity are particularly well-suited for this purpose. We used one such model (the University of Victoria Earth System Climate Model) and carried out a series of sensitivity experiments by varying a single model parameter through changing the atmospheric CO2 concentration. The unanalyzed World Ocean Atlas SST and the observed sea-ice concentration served as present-day targets. The sparse data coverage as implied by the locations of 756 ocean sediment cores from the MARGO SST database was indeed sufficient to determine the best fit. As anticipated, it turned out to be the 365 ppm experiment. We also found that the 200 ppm experiment came surprisingly close to what is commonly expected for the Last Glacial Maximum ocean circulation. Our strategy has a number of advantages over more traditional mapping methods, e.g., there is no need to force the results of different proxies into a single map, because they can be compared to the model output one at a time, properly taking into account the different seasons of plankton growth or varying depth habitats. It can be extended to more model parameters and even be automated.

  9. Independent Temperature and Salinity Reconstruction from Coral Skeleton

    Science.gov (United States)

    Juillet-Leclerc, A.; Thiria, S.; Peron, C.

    2007-12-01

    Massive coral skeleton offers the best-suited material for reconstruction of tropical climate during the last century. Indeed, growth rate of some species is fast enough to provide high-resolution (monthly) sampling. The formation of a big colony may cover continuously several decades, even, several centuries. Chronology is made easy by annual growth layers. Finally, aragonite, which composes this skeleton, presents several proxies, such as isotopes and trace elements. However, the aragonite deposit is biologically controlled and all the proxies are influenced by both environmental and biologic factors. By example, temperature and light may affect both oxygen isotopes as well as Sr/Ca. Thus, these two parameters are difficult to separate from seasonal records. Such an effect may be neglected for annual averages or filtered records. Indeed, the difference of irradiation recorded during two consecutive years is much limited than between winter and summer (see PP24). It is the reason that annual and monthly reconstitutions will be conducted separately. In addition, it seems that other factors are the causes of the high variability shown by all the proxies. The common factor affecting them is related with metabolism. We suppose that proxies being measured from a powder collected from homogeneous material are fractionated by external factors through the same biologic filter during the time, but each of them differently because incorporated in the mineral by different ways. This is the reason that we used neural network (NN), which learns the behavior of several proxies submitted to one forcing during a known period. Then, the complex relationship recognized by neurons between the different proxies is used to "predict" the forcing during the past. The relationship between external factor and proxies remains hidden, but this could not be used for other colonies, even for other sampling from a same head. By this way, it is possible to calibrate temperature and salinity and

  10. NOAA Climate Data Record (CDR) of Sea Surface Temperature (SST) from AVHRR Pathfinder, Version 5.2

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The AVHRR Pathfinder Version 5.2 Sea Surface Temperature data set (PFV52) is a collection of global, twice-daily 4km sea surface temperature data produced in a...

  11. Investigating genetic loci that encode plant-derived paleoclimate proxies

    Science.gov (United States)

    Bender, A. L. D.; Suess, M.; Chitwood, D. H.; Bradley, A. S.

    2016-12-01

    traits. Our results have important implications for uncovering the degree to which we can expect environmental versus genetic factors to modulate variability in n-alkane δD values. These findings can inform the interpretation of the proxy signal recovered from the geological record.

  12. Calcium isotopic composition of high-latitude proxy carrier Neogloboquadrina pachyderma (sin.

    Directory of Open Access Journals (Sweden)

    A. Eisenhauer

    2009-01-01

    Full Text Available The accurate reconstruction of sea surface temperature (SST history in climate-sensitive regions (e.g. tropical and polar oceans became a challenging task in palaeoceanographic research. Biogenic shell carbonate SST proxies successfully developed for tropical regions often fail in cool water environments. Their major regional shortcomings and the cryptic diversity now found within the major high latitude proxy carrier Neogloboquadrina pachyderma (sin. highlight an urgent need to explore complementary SST proxies for these cool-water regions. Here we incorporate the genetic component into a calibration study of a new SST proxy for the high latitudes. We found that the calcium isotopic composition (δ44/40Ca of calcite from genotyped net catches and core-top samples of the planktonic foraminifera Neogloboquadrina pachyderma (sin. is related to temperature and unaffected by genetic variations. The temperature sensitivity has been found to be 0.17 (±0.02‰ per 1°C, highlighting its potential for downcore applications in open marine cool-water environments. Our results further indicate that in extreme polar environments, below a critical threshold temperature of 2.0 (±0.5°C associated with salinities below 33.0 (±0.5‰, a prominent shift in biomineralization affects the δ44/40Ca of genotyped and core-top N. pachyderma (sin., becoming insensitive to temperature. These findings highlight the need of more systematic calibration studies on single planktonic foraminiferal species in order to unravel species-specific factors influencing the temperature sensitivity of Ca isotope fractionation and to validate the proxies' applicability.

  13. Legal requirements governing proxy voting in Denmark

    DEFF Research Database (Denmark)

    Werlauff, Erik

    2008-01-01

    The requirements in Danish company law concerning proxy voting in companies whose shares have been accepted for listing on a regulated market have been successively tightened in recent years, and corporate governance principles have also led to the introduction of several requirements concerning...... proxy holders. A thorough knowledge of these requirements is important not only for the listed companies but also for their advisers and investors in Denmark and abroad. This article considers these requirements as well as the additional requirements which will derive from Directive 2007....../36 on the exercise of shareholders' rights in listed companies, which must be implemented by 3 August 2009. It is pointed out that companies may provide with advantage in their articles of association for both the existing and the forthcoming requirements at this early stage....

  14. Observable Proxies For 26 Al Enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Fryer, Christopher L [Los Alamos National Laboratory; Young, Patrick A [Los Alamos National Laboratory; Ellinger, Carola I [ASU; Arnett, William D [UNIV ARIZONA

    2008-01-01

    We consider the cospatial production of elements in supernova explosions to find observationally detectable proxies for enhancement of {sup 26}Al in supernova ejecta and stellar systems. Using four progenitors we explore a range of 1D explosions at different energies and an asymmetric 3D explosion. We find that the most reliable indicator of the presence of {sup 26}Al in unmixed ejecta is a very low S/Si ratio ({approx} 0.05). Production of N in O/S/Si-rich regions is also indicative. The biologically important element P is produced at its highest abundance in the same regions. Proxies should be detectable in supernova ejecta with high spatial resolution multi wavelength observations, but the small absolute abundance of material injected into a proto-planetary disk makes detection unlikely in existing or forming stellar/planetary systems.

  15. Non-destructive foraminiferal paleoclimatic proxies: A brief insight

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.

    Non-Destructive Foraminiferal Paleoclimatic Proxies: A Brief Insight The knowledge of past climate can help us to understand imminent climatic changes. Oceans are the vast archives of past climate. Various indirect techniques termed as proxies...

  16. Method for determining thermo-physical properties of specimens. [photographic recording of changes in thin film phase-change temperature indicating material in wind tunnel

    Science.gov (United States)

    Jones, R. A. (Inventor)

    1974-01-01

    The square root of the product of thermophysical properties q, c and k, where p is density, c is specific heat and k is thermal conductivity, is determined directly on a test specimen such as a wind tunnel model. The test specimen and a reference specimen of known specific heat are positioned at a given distance from a heat source. The specimens are provided with a coating, such as a phase change coating, to visually indicate that a given temperature was reached. A shutter interposed between the heat source and the specimens is opened and a motion picture camera is actuated to provide a time record of the heating step. The temperature of the reference specimen is recorded as a function of time. The heat rate to which both the test and reference specimens were subjected is determined from the temperature time response of the reference specimen by the conventional thin-skin calorimeter equation.

  17. Multi-proxy constraints on sapropel formation during the late Pliocene of central Mediterranean (southwest Sicily)

    Science.gov (United States)

    Plancq, Julien; Grossi, Vincent; Pittet, Bernard; Huguet, Carme; Rosell-Melé, Antoni; Mattioli, Emanuela

    2015-06-01

    The late Pliocene (Piacenzian) in the Mediterranean region was punctuated by short-lived episodes of widespread deposition of organic-rich sedimentary layers known as sapropels. The causes of their formation remain a long-standing debate in the science community, and require disentangling the roles of climatic/oceanographic processes that triggered higher primary productivity or enhanced organic matter preservation. The lack of data, especially of sea temperatures at sufficient temporal resolution, is one of the main challenges to solve this debate. Here, we present new organic geochemistry and micropaleontological data from the late Pliocene at Punta Grande/Punta Piccola sections (southwest Sicily) that allow untangling the mechanisms that favored the formation of two sapropel series (noted S and A) in the central Mediterranean area during this period. Sea surface (SSTs) and subsurface temperatures were estimated using three distinct organic geochemical proxies namely the alkenone unsaturation index (UK‧37), the long-chain diol index (LDI) and the tetraether index (TEX86). Reconstructed SSTs are relatively stable throughout the late Pliocene and ∼4 °C higher than modern Mediterranean SSTs, which is consistent with the climatic conditions inferred for this period from paleoclimate modeling. An increase in SST is, however, recorded by UK‧37 and LDI proxies across each sapropel horizon, supporting that the two sapropel series S and A were formed during warmer climate conditions. The comparison of SST data with variations in accumulation rates of total organic carbon and lipid-biomarkers (alkenones, long-chain alkyl diols, archaeal and bacterial tetraethers), and with changes in calcareous nannofossil assemblages, indicates that the studied sapropels might have formed under different environmental conditions. The first series of sapropels (S), deposited between 3.1 and 2.8 Ma, is likely due to a better preservation of organic matter, induced by the development

  18. Implementasi Proxy Server Dengan Linux Clear OS 5.2

    OpenAIRE

    Setiadi, Aprian

    2013-01-01

    Tugas Akhir ini membahas mengenai cara untuk membangun sebuah proxy server dalam jaringan LAN. Jaringan LAN yang dibangun menggunakan arsitektur topologi star dengan menjadikan komputer server sebagai Gateway Server dan Proxy Server, sehingga tidak membutuhkan perangkat tambahan Router yang berfungsi sebagai Gateway Server. Proxy Server yang yang dibangun menggunakan metode Transparent Mode, sehingga pada komputer klien tidak perlu mengkonfigurasi port proxy server pada Web Browser. Hasil ya...

  19. Simulation of Wake Vortex Radiometric Detection via Jet Exhaust Proxy

    Science.gov (United States)

    Daniels, Taumi S.

    2015-01-01

    This paper describes an analysis of the potential of an airborne hyperspectral imaging IR instrument to infer wake vortices via turbine jet exhaust as a proxy. The goal was to determine the requirements for an imaging spectrometer or radiometer to effectively detect the exhaust plume, and by inference, the location of the wake vortices. The effort examines the gas spectroscopy of the various major constituents of turbine jet exhaust and their contributions to the modeled detectable radiance. Initially, a theoretical analysis of wake vortex proxy detection by thermal radiation was realized in a series of simulations. The first stage used the SLAB plume model to simulate turbine jet exhaust plume characteristics, including exhaust gas transport dynamics and concentrations. The second stage used these plume characteristics as input to the Line By Line Radiative Transfer Model (LBLRTM) to simulate responses from both an imaging IR hyperspectral spectrometer or radiometer. These numerical simulations generated thermal imagery that was compared with previously reported wake vortex temperature data. This research is a continuation of an effort to specify the requirements for an imaging IR spectrometer or radiometer to make wake vortex measurements. Results of the two-stage simulation will be reported, including instrument specifications for wake vortex thermal detection. These results will be compared with previously reported results for IR imaging spectrometer performance.

  20. 12 CFR 7.2002 - Director or attorney as proxy.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Director or attorney as proxy. 7.2002 Section 7... OPERATIONS Corporate Practices § 7.2002 Director or attorney as proxy. Any person or group of persons, except the bank's officers, clerks, tellers, or bookkeepers, may be designated to act as proxy. The bank's...

  1. Physicians' Involvement with the New York State Health Care Proxy

    Science.gov (United States)

    Heyman, Janna C.; Sealy, Yvette M.

    2011-01-01

    This study examined physicians' attitude, involvement, and perceived barriers with the health care proxy. A cross sectional, correlational design was used to survey practicing physicians (N = 70). Physicians had positive attitudes toward the health care proxy and indicated that the most significant barriers to health care proxy completion were…

  2. Volcanic influence on centennial to millennial Holocene Greenland temperature change.

    Science.gov (United States)

    Kobashi, Takuro; Menviel, Laurie; Jeltsch-Thömmes, Aurich; Vinther, Bo M; Box, Jason E; Muscheler, Raimund; Nakaegawa, Toshiyuki; Pfister, Patrik L; Döring, Michael; Leuenberger, Markus; Wanner, Heinz; Ohmura, Atsumu

    2017-05-03

    Solar variability has been hypothesized to be a major driver of North Atlantic millennial-scale climate variations through the Holocene along with orbitally induced insolation change. However, another important climate driver, volcanic forcing has generally been underestimated prior to the past 2,500 years partly owing to the lack of proper proxy temperature records. Here, we reconstruct seasonally unbiased and physically constrained Greenland Summit temperatures over the Holocene using argon and nitrogen isotopes within trapped air in a Greenland ice core (GISP2). We show that a series of volcanic eruptions through the Holocene played an important role in driving centennial to millennial-scale temperature changes in Greenland. The reconstructed Greenland temperature exhibits significant millennial correlations with K + and Na + ions in the GISP2 ice core (proxies for atmospheric circulation patterns), and δ 18 O of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Therefore, we conclude that volcanic activity played a critical role in driving centennial to millennial-scale Holocene temperature variability in Greenland and likely beyond.

  3. Holocene Climate, Fire and Vegetation Change Inferred from Lacustrine Proxies in the Tropical Andes, Laguna Yanacocha, SE Peru

    Science.gov (United States)

    Axford, Y.; Isaacson, M.; Matthews-Bird, F.; Schellinger, G. C.; Carrio, C. L.; Kelly, M. A.; Lowell, T. V.; Beal, S. A., Jr.; Stroup, J. S.; Tapia, P. M.

    2016-12-01

    We present a 12,000-year long paleoenvironmental reconstruction from a small high-elevation lake in southeastern Peru. Climate and environmental change are inferred from chironomid species assemblages, charcoal abundance, size and morphology, and the abundance of some important pollen and spore types (Poaceae, Asteraceae, Isoetes). We employ a new chironomid training set developed for tropical South America (Matthews-Bird et al. 2016) to interpret shifts in chironomid assemblages. The sedimentary record from Yanacocha was first discussed by Beal et al. (2014), who reconstructed Hg deposition and measured metals, biogenic silica and loss-on-ignition through the Holocene. Additional downcore proxies are presented by Stroup et al. (this meeting). Yanacocha sits at 4910 m asl and less than 2 km from Quelccaya Ice Cap (QIC), but the lake's watershed has been topographically isolated from glacier meltwater since 12.3 ka. We compare our inferences from biological proxies with independent constraints on paleoclimate derived from published reconstructions of QIC fluctuations. Previous studies found that temperature was the primary driver of late Holocene fluctuations of QIC (e.g., Stroup et al. 2014), but records from the broader region indicate the Holocene also saw major changes in hydroclimate. Most modern precipitation at Yanacocha derives from the Amazon Basin to the east, and El Niño years are associated with drier conditions. Holocene sediments at Yanacocha likely thus record both changes in temperature and hydroclimate. Vegetation was sparse and no charcoal was preserved prior to 11.7 ka, whereas the early Holocene saw the highest overall pollen concentrations of the entire record and the onset of charcoal preservation. An increase in charcoal abundance, decrease in pollen concentrations, and shifts in vegetation and chironomid assemblages at Yanacocha suggest drier conditions from 9 to 3.5 ka, consistent with widespread regional evidence for early to middle

  4. One thousand years of fires: Integrating proxy and model data

    Directory of Open Access Journals (Sweden)

    Natalie Marie Kehrwald

    2016-04-01

    Full Text Available The current fires raging across Indonesia are emitting more carbon than the annual fossil fuel emissions of Germany or Japan, and the fires are still consuming vast tracts of rainforest and peatlands. The National Interagency Fire Center (www.nifc.gov notes that 2015 is one worst fire years on record in the U.S., where more than 9 million acres burned -- equivalent to the combined size of Massachusetts and New Jersey. The U.S. and Indonesian fires have already displaced tens of thousands of people, and their impacts on ecosystems are still unclear. In the case of Indonesia, the burning peat is destroying much of the existing soil, with unknown implications for the type of vegetation regrowth. Such large fires result from a combination of fire management practices, increasing anthropogenic land use, and a changing climate. The expected increase in fire activity in the upcoming decades has led to a surge in research trying to understand their causes, the factors that may have influenced similar times of fire activity in the past, and the implications of such fire activity in the future. Multiple types of complementary data provide information on the impacts of current fires and the extent of past fires. The wide array of data encompasses different spatial and temporal resolutions (Figure 1 and includes fire proxy information such as charcoal and tree ring fire scars, observational records, satellite products, modern emissions data, fire models within global land cover and vegetation models, and sociodemographic data for modeling past human land use and ignition frequency. Any single data type is more powerful when combined with another source of information. Merging model and proxy data enables analyses of how fire activity modifies vegetation distribution, air and water quality, and proximity to cities; these analyses in turn support land management decisions relating to conservation and development.

  5. A Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet

    Science.gov (United States)

    Hall, Dorothy K.; Comiso, Josefino C.; DiGirolamo, Nicolo E.; Shuman, Christopher A.; Key, Jeffrey R.; Koenig, Lora S.

    2011-01-01

    We have developed a climate-quality data record of the clear-sky surface temperature of the Greenland Ice Sheet using the Moderate-Resolution Imaging Spectroradiometer (MODIS) Terra ice-surface temperature (1ST) algorithm. A climate-data record (CDR) is a time series of measurements of sufficient length, consistency, and continuity to determine climate variability and change. We present daily and monthly Terra MODIS ISTs of the Greenland Ice Sheet beginning on 1 March 2000 and continuing through 31 December 2010 at 6.25-km spatial resolution on a polar stereographic grid within +/-3 hours of 17:00Z or 2:00 PM Local Solar Time. Preliminary validation of the ISTs at Summit Camp, Greenland, during the 2008-09 winter, shows that there is a cold bias using the MODIS IST which underestimates the measured surface temperature by approximately 3 C when temperatures range from approximately -50 C to approximately -35 C. The ultimate goal is to develop a CDR that starts in 1981 with the Advanced Very High Resolution (AVHRR) Polar Pathfinder (APP) dataset and continues with MODIS data from 2000 to the present. Differences in the APP and MODIS cloud masks have so far precluded the current IST records from spanning both the APP and MODIS IST time series in a seamless manner though this will be revisited when the APP dataset has been reprocessed. The Greenland IST climate-quality data record is suitable for continuation using future Visible Infrared Imager Radiometer Suite (VIIRS) data and will be elevated in status to a CDR when at least 9 more years of climate-quality data become available either from MODIS Terra or Aqua, or from the VIIRS. The complete MODIS IST data record will be available online in the summer of 2011.

  6. Comparison between remotely-sensed sea-surface temperature (AVHRR and in situ records in San Matías Gulf (Patagonia, Argentina

    Directory of Open Access Journals (Sweden)

    Gabriela N Williams

    2014-03-01

    Full Text Available In situ records of sea surface temperature collected between 2005 and 2009 were used to compare, for the first time, the temperature estimated by the Multichannel algorithms (MCSST of the Advanced Very High Resolution Radiometer (AVHRR sensors in San Matías Gulf, in the north of the Argentinean Patagonian Continental Shelf (between 40°47'-42°13'S. Match-ups between in situ records and satellite sea surface temperature (SST were analyzed. In situ records came from fixed stations and oceanographic cruises, while satellite data came from different NOAA satellites. The fitting of temperature data to a Standard Major Axis (SMA type II regression model indicated that a high proportion of the total variance (0.53< r² <0.99 was explained by this model showing a high correlation between in situ data and satellite estimations. The mean differences between satellite and in situ data for the full data set were 1.64 ± 1.49°C. Looking separately into in situ data from different sources and day and night estimates from different NOAA satellites, the differences were between 0.30 ± 0.60°C and 2.60 ± 1.50°C. In this paper we discuss possible reasons for the above-mentioned performance of the MCSST algorithms in the study area.

  7. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Cloud Top Temperature (CTT) Environmental Data Record (EDR) from IDPS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument onboard the...

  8. NOAA JPSS Visible Infrared Imaging Radiometer Suite (VIIRS) Ice Surface Temperature (IST) Environmental Data Record (EDR) from IDPS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains a high quality operational Environmental Data Record (EDR) from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument onboard the...

  9. NOAA Climate Data Record (CDR) of MSU and AMSU-A Mean Layer Temperatures, UAH Version 5.4 (Superseded)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Please note: this dataset has been superseded by a newer version (see below). This version is archived offline by NOAA NCEI. This Climate Data Record (CDR) includes...

  10. Proxy Graph: Visual Quality Metrics of Big Graph Sampling.

    Science.gov (United States)

    Nguyen, Quan Hoang; Hong, Seok-Hee; Eades, Peter; Meidiana, Amyra

    2017-06-01

    Data sampling has been extensively studied for large scale graph mining. Many analyses and tasks become more efficient when performed on graph samples of much smaller size. The use of proxy objects is common in software engineering for analysis and interaction with heavy objects or systems. In this paper, we coin the term 'proxy graph' and empirically investigate how well a proxy graph visualization can represent a big graph. Our investigation focuses on proxy graphs obtained by sampling; this is one of the most common proxy approaches. Despite the plethora of data sampling studies, this is the first evaluation of sampling in the context of graph visualization. For an objective evaluation, we propose a new family of quality metrics for visual quality of proxy graphs. Our experiments cover popular sampling techniques. Our experimental results lead to guidelines for using sampling-based proxy graphs in visualization.

  11. Lithium isotopes in foraminifera shells as a novel proxy for the ocean dissolved inorganic carbon (DIC)

    Science.gov (United States)

    Vigier, Nathalie; Rollion-Bard, Claire; Levenson, Yaël; Erez, Jonathan

    2015-01-01

    Past ocean pH and pCO2 are critical parameters for establishing relationships between Earth's climate and the carbon cycle. Previous pCO2 estimates are associated with large uncertainties and are debated. In this study, laboratory cultures of the foraminiferan genus Amphistegina were performed in order to examine the possible factors that control the Li isotope composition (δ7Li) of their shells. δ7Li is insensitive to temperature and pH variations but correlates positively with the Dissolved Inorganic Carbon (DIC) of seawater. Li/Ca ratio in the shells shows negative correlation with δ7Li, consistent with published data for planktonic foraminifera from core tops and from short periods during the Cenozoic. We propose that the sensitivity of δ7Li and Li/Ca ratio to DIC is a biological phenomenon and is related to biomineralization mechanisms in foraminifera. We used the published foraminiferal δ7Li records, and our experimental results, to determine the paleo-ocean DIC and pH for the last glacial-interglacial cycle. The results are consistent with published estimates of pH and pCO2 based on boron isotopes and ice cores. We suggest Li and its isotopes may serve as a new complementary proxy for the paleo-ocean carbonate chemistry.

  12. Geochemical Proxies for Enhanced Process Control of Underground Coal Gasification

    Science.gov (United States)

    Kronimus, A.; Koenen, M.; David, P.; Veld, H.; van Dijk, A.; van Bergen, F.

    2009-04-01

    Underground coal gasification (UCG) represents a strategy targeting at syngas production for fuel or power generation from in-situ coal seams. It is a promising technique for exploiting coal deposits as an energy source at locations not allowing conventional mining under economic conditions. Although the underlying concept has already been suggested in 1868 and has been later on implemented in a number of field trials and even at a commercial scale, UCG is still facing technological barriers, impeding its widespread application. Field UCG operations rely on injection wells enabling the ignition of the target seam and the supply with oxidants (air, O2) inducing combustion (oxidative conditions). The combustion process delivers the enthalpy required for endothermic hydrogen production under reduction prone conditions in some distance to the injection point. The produced hydrogen - usually accompanied by organic and inorganic carbon species, e.g. CH4, CO, and CO2 - can then be retrieved through a production well. In contrast to gasification of mined coal in furnaces, it is difficult to measure the combustion temperature directly during UCG operations. It is already known that geochemical parameters such as the relative production gas composition as well as its stable isotope signature are related to the combustion temperature and, consequently, can be used as temperature proxies. However, so far the general applicability of such relations has not been proven. In order to get corresponding insights with respect to coals of significantly different rank and origin, four powdered coal samples covering maturities ranging from Ro= 0.43% (lignite) to Ro= 3.39% (anthracite) have been gasified in laboratory experiments. The combustion temperature has been varied between 350 and 900 ˚ C, respectively. During gasification, the generated gas has been captured in a cryo-trap, dried and the carbon containing gas components have been catalytically oxidized to CO2. Thereafter, the

  13. Iron content of soils as a precipitation proxy

    Science.gov (United States)

    Dzombak, R.; Sheldon, N. D.

    2016-12-01

    Given that different iron phases form under different precipitation and drainage regimes, soil iron content could be used as a proxy for both volume and seasonality of precipitation. Constraining these factors is important for predicting future precipitation trends, especially for a warmer climate that will likely see more frequent extreme weather events. Specifically, using paleoprecipitation data from periods of higher temperatures and atmospheric CO2 concentrations helps inform models of future `greenhouse' climate. Forty-five modern samples from across the continental United States were analyzed, with MAP ranging from 200 to 1200 mm yr-1 and MAT ranging from 5 to 22°C. Soil types included Alfisols (N=15), Inceptisols (N=8), Mollisols (N=15), and Aridisols (N=7), and ranged from seasonally wet to well-drained. Analytical techniques included combustion-elemental analysis and organic carbon isotope analysis, a sequential iron extraction modified with a sodium hypochlorite step for the extraction of organic matter-bound iron, and the extraction of iron sulfides. The sequential extractions yield five different `pools' of iron found in sediment: crystalline iron oxides (e.g., goethite, hematite), magnetite, carbonate-bound, organic matter-bound, and labile/easily reducible iron minerals (e.g., ferrihydrite). Analysis by ICP-OES yielded a strong relationship between magnetite-bound iron and MAP, and fair relationships between the other iron pools and MAP. Individual soil orders tended to show stronger relationships to the iron pools than all soils analyzed together, potentially indicating the need for separate proxy relationships for each soil order. Pyrite concentrations were well below 1% by weight for these soils, suggesting that none of these soils has a long enough wet season to encourage its formation and that the presence vs. absence of pyrite in paleosols may be a useful proxy for soil moisture state. In contrast to some earlier work, no significant

  14. Light is an active contributor to the vital effects of coral skeleton proxies

    Science.gov (United States)

    Juillet-Leclerc, Anne; Reynaud, Stéphanie; Dissard, Delphine; Tisserand, Guillaume; Ferrier-Pagès, Christine

    2014-09-01

    Symbiotic colonies of the coral Acropora sp. were cultured in a factorial design of three temperatures (21, 25 and 28 °C) and two light intensities (200 and 400 μmol photon m-2 s-1), under constant conditions. A temperature of 25 °C and a light intensity of 200 μmol photon m-2 s-1 was the starting culture condition. Metabolic (photosynthesis, respiration, calcification and surface expansion rate) and geochemical measurements (δ18O, δ13C, Sr/Ca and Mg/Ca) were conducted on 6 colonies for each experimental condition. Metabolic measurements confirmed that respiration, photosynthesis, calcification and surface expansion rate responded to the combined effect of temperature and light. Under each light intensity, mean calcification rate was linearly correlated with mean photosynthetic activity. Geochemical measurements were also influenced by temperature and, to a lesser degree, by light. All geochemical proxies measured on 6 nubbins showed a wide scattering of values, regardless of the environmental condition. Compared to the other proxies, δ18O exhibited a different behavior. It was the only proxy exhibiting temperature tracer behavior. However, while mean values of Sr/Ca, Mg/Ca and δ13C were well correlated, the correlation between the later and mean δ18O differed with light level. This suggests that both skeleton deposition and temperature oxygen fractionation differs according to light intensity. Overall, the effect of light on geochemical values seems to compromise the use of proxy calibrations solely based on temperature influence. Under high light conditions, the great amplitude shown by individual net photosynthesis is directly proportional to the highly variable zooxanthellae density. As light is affecting all of the proxies, we thus assume that the strong geochemical variability observed could be explained by various algae densities, each nubbin responding according to its zooxanthellae amount. Accordingly, we suggest that each symbiosome (the

  15. Adaptability in CORBA: The Mobile Proxy Approach

    DEFF Research Database (Denmark)

    Aziz, B.; Jensen, Christian D.

    2000-01-01

    are inherently open, heterogeneous, and dynamic environments integrating a wide range of platforms, operating systems and applications from a number of different sources. In this paper, we propose to use mobile proxies to provide adaptability in distributed applications integrated using the CORBA technology......Adaptability is one of the most important challenges in modern distributed systems. It may be defined as the ease with which a software application satisfies the different system constraints and the requirements of users and other applications. Adaptability is needed because distributed systems...

  16. Availability of self-recorded axillary temperature for assessment of thermic effects of food: relationship between HDL-cholesterol level and postprandial thermoregulation in type 2 diabetic patients.

    Science.gov (United States)

    Suzuki, S; Nishio, S-i; Ishii, H; Sato, A; Takeda, T; Komatsu, M

    2012-02-01

    The present study was performed to develop a simple procedure for assessment of body temperature and to determine whether postprandial thermoregulation is related to metabolic regulation in diabetic patients. We examined 101 male and female subjects with diabetes. Axillary temperature was measured prior to and after all meals (3 meals per day) and self-recorded for 1 week. The averages were calculated. Positive postprandial thermoregulation (PPT) was defined as a pattern in which each of 3 average postprandial temperatures was higher than the corresponding 3 preprandial temperatures. Negative postprandial thermoregulation (NPT) was defined as the pattern except for PPT. A significant increase in postprandial temperature was observed. With the exception of high-density lipoprotein (HDL)-cholesterol levels, there were no relationships between the categorized postprandial thermoregulation and other factors, including age, sex, body mass index, thyroid function, HbA1c, diabetic complications, lipid metabolism, and calorie intake. Logistic analysis indicated an independent positive relation between HDL-cholesterol and PPT. A simple method for measurement of body temperature indicated that HDL-cholesterol level was predominantly associated with thermic effects of food in diabetic patients, while other metabolic factors showed no such relations. HDL-cholesterol may affect the postprandial regulation of body temperature in diabetic patients. © J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York.

  17. A model to approximate lake temperature from gridded daily air temperature records and its application in risk assessment for the establishment of fish diseases in the UK.

    Science.gov (United States)

    Thrush, M A; Peeler, E J

    2013-10-01

    Ambient water temperature is a key factor controlling the distribution and impact of disease in fish populations, and optimum temperature ranges have been characterised for the establishment of a number important aquatic diseases exotic to the UK. This study presents a simple regression method to approximate daily average surface water temperature in lakes of 0.5-15 ha in size across the UK using 5 km(2) gridded daily average air temperatures provided by the UK Meteorological Office. A Geographic information system (GIS) is used to present thematic maps of relative risk scores established for each grid cell based on the mean number of days per year that water temperature satisfied optimal criteria for the establishment of two economically important pathogens of cyprinid fish (koi herpesvirus (KHV) and spring viraemia of carp virus (SVCV)) and the distribution and density of fish populations susceptible to these viruses. High-density susceptible populations broadly overlap the areas where the temperature profiles are optimal for KHV (central and south-east England); however, few fish populations occur in areas where temperature profiles are most likely to result in the establishment of spring viremia of carp (SVC) (namely northern England and Scotland). The highest grid-cell risk scores for KHV and SVC were 7 and 6, respectively, out of a maximum score of 14. The proportion of grid cells containing susceptible populations with risk scores of 5 or more was 37% and 5% for KHV and SVC, respectively. This work demonstrates a risk-based approach to inform surveillance for exotic pathogens in aquatic animal health management, allowing efficient use of resources directed towards higher risk animals and geographic areas for early disease detection. The methodology could be used to examine the change in distribution of high-risk areas for both exotic and endemic fish diseases under different climate change scenarios. © 2012 Crown copyright Reproduced with the permission

  18. 6-kyr record of flood frequency and intensity in the western Mediterranean Alps - Interplay of solar and temperature forcing

    Science.gov (United States)

    Pierre, Sabatier; Bruno, Wilhelm; Francesco, Ficetola Gentile; Fanny, Moiroux; Jérôme, Poulenard; Anne-Lise, Develle; Adeline, Bichet; Wentao, Chen; Cécile, Pignol; Jean-Louis, Reyss; Ludovic, Gielly; Manon, Bajard; Yves, Perrette; Emmanuel, Malet; Pierre, Taberlet; Fabien, Arnaud

    2017-08-01

    The high-resolution sedimentological and geochemical analysis of a sediment sequence from Lake Savine (Western Mediterranean Alps, France) led to the identification of 220 event layers for the last 6000 years. 200 were triggered by flood events and 20 by underwater mass movements possibly related to earthquakes that occurred in 5 clusters of increase seismicity. Because human activity could influence the flood chronicle, the presence of pastures was reconstructed through ancient DNA, which suggested that the flood chronicle was mainly driven by hydroclimate variability. Weather reanalysis of historical floods allow to identify that mesoscale precipitation events called ;East Return; events were the main triggers of floods recorded in Lake Savine. The first part of this palaeoflood record (6-4 kyr BP) was characterized by increases in flood frequency and intensity in phase with Northern Alpine palaeoflood records. By contrast, the second part of the record (i.e., since 4 kyr BP) was phased with Southern Alpine palaeoflood records. These results suggest a palaeohydrological transition at approximately 4 kyr BP, as has been previously described for the Mediterranean region. This may have resulted in a change of flood-prone hydro-meteorological processes, i.e., in the balance between occurrence and intensity of local convective climatic phenomena and their influence on Mediterranean mesoscale precipitation events in this part of the Alps. At a centennial timescale, increases in flood frequency and intensity corresponded to periods of solar minima, affecting climate through atmospheric changes in the Euro-Atlantic sector.

  19. NOAA Climate Data Record (CDR) of AMSU-A Level 1c Brightness Temperature, Version 1.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains Level 1c inter-calibrated brightness temperatures from the Advanced Microwave Sounding Unit-A (AMSU-A) sensors onboard six polar orbiting...

  20. NOAA Climate Data Record (CDR) of MSU and AMSU-A Mean Layer Temperatures, UAH Version 6.0

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset includes monthly gridded temperature anomalies on a global 2.5 x 2.5 degree grid derived from Microwave Sounding Unit (MSU) and Advanced Microwave...

  1. Munchausen syndrome by proxy: ongoing clinical challenges.

    Science.gov (United States)

    Squires, Janet E; Squires, Robert H

    2010-09-01

    In 1977, Roy Meadow, a pediatric nephrologist, first described a condition he subsequently coined Munchausen syndrome by proxy. The classic form involves a parent or other caregiver who inflicts injury or induces illness in a child, deceive the treating physician with fictitious or exaggerated information, and perpetrate the trick for months or years. A related form of pathology is more insidious and more common but also damaging. It involves parents who fabricate or exaggerate symptoms of illness in children, causing overly aggressive medical evaluations and interventions. The common thread is that the treating physician plays a role in inflicting the abuse upon the child. Failure to recognize the problem is common because the condition is often not included in the differential diagnosis of challenging or confusing clinical problems. We believe that a heightened "self-awareness" of the physician's role in Munchausen syndrome by proxy will prevent or reduce the morbidity and mortality associated with this diagnosis. In addition, we believe contemporary developments within the modern health care system likely facilitate this condition.

  2. Late Holocene High Discharge and Erosion Events Inferred from Sediment Proxies and Catchment Geomorphology, Lake Vuoksjávrátje, NW Sweden

    Science.gov (United States)

    Berntsson, A.; Jansson, K. N.; Kylander, M. E.; De Vleeschouwer, F.; Bertrand, S.

    2014-12-01

    Alpine lakes in NW Sweden are highly sensitive to variations in catchment erosion and in precipitation. Previous studies aimed at reconstructing past summer temperatures have suggested that this sensitivity may influence chironomid species composition enough to cause bias in quantitative temperature reconstructions. In this study we have analysed lake sediments covering the last 5100 years from Lake Vuoksjávrátje in NW Sweden and catchment geomorphology with the aim to separate between different erosional regimes in the lake and its catchment and to identify sediment sources and processes behind sediment deposition in the lake basin. Methods include XRF core scanning, grain size analysis, chironomid analysis, TOC and C/N analysis and detailed mapping of geomorphology. From the integrated results we identify time intervals with increased catchment erosion, inferred to result from intense precipitation. Based on the combined proxy data it was concluded that a major flood event took place at the Vindelfjällen site c. 2800 cal BP, unique for the 5100-year long record. The chironomid species composition shows stronger influence from wetland surface erosion at c. 2800 cal BP and during the last c. 1000 years. By combining multi-proxy lake sediment analysis with study of catchment geomorphology it is possible to improve the understanding of Late Holocene hydro-climatic change and how it may influence Arctic alpine lakes.

  3. Asymmetric trends in seasonal temperature variability in instrumental records from ten stations in Switzerland, Germany and the UK from 1864 to 2012.

    Science.gov (United States)

    Matiu, Michael; Ankerst, Donna P; Menzel, Annette

    2016-01-01

    While the rise in global mean temperature over the past several decades is now widely acknowledged, the issue as to whether and to what extent temperature variability is changing continues to undergo debate. Here, variability refers to the spread of the temperature distribution. Much attention has been given to the effects that changes in mean temperature have on extremes, but these changes are accompanied by changes in variability, and it is actually the two together, in addition to all aspects of a changing climate pattern, that influence extremes. Since extremes have some of the largest impacts on society and ecology, changing temperature variability must be considered in tandem with a gradually increasing temperature mean. Previous studies of trends in temperature variability have produced conflicting results. Here we investigated ten long-term instrumental records in Europe of minimum, mean and maximum temperatures, looking for trends in seasonal, annual and decadal measures of variability (standard deviation and various quantile ranges) as well as asymmetries in the trends of extreme versus mean temperatures via quantile regression. We found consistent and accelerating mean warming during 1864-2012. In the last 40 years (1973-2012) trends for Tmax were higher than for Tmin, reaching up to 0.8 °C per 10a in spring. On the other hand, variability trends were not as uniform: significant changes occurred in opposing directions depending on the season, as well as when comparing 1864-2012 trends to those of 1973-2012. Moreover, if variability changed, then it changed asymmetrically, that is only in the part above or below the median. Consequently, trends in the extreme high and low quantiles differed. Regional differences indicated that in winter, high-alpine stations had increasing variability trends for Tmax especially at the upper tail compared to no changes or decreasing variability at low altitude stations. In contrast, summer variability increased at all

  4. Biomarker records of Holocene climate variations in Asian interior

    Science.gov (United States)

    Song, M.; Liu, Z.; Liu, W.; Zhao, C.; Li, S.; He, Y.

    2012-12-01

    Understanding Holocene climate fluctuation may provide clues to projection of future climate change. Lake sediments in the arid central Asia (ACA), as an archive of past climate information, keep attracting considerable interest. We have retrieved several sediment cores from Lake Manas, an endorheic lake in Zunggar desert, Xinjiang Province, China. Biomarker proxies including alkenone Uk'37, %C37:4 and C37 concentration (C37 Conc), and physical proxies including density and magnetic susceptibility (MS) have been analyzed. We have found substantial climatic and environmental changes during the late Holocene. Density, MS and Uk'37 values are high during Medieval Warm Period (MWP) and C37 Conc is very low. During the Little Ice Age, density and MS decrease, Uk'37 values drop to near 0.1, C37 Conc is increased by 2 to 3 magnitude. Thus, warm and dry conditions dominated MWP while cold and wet conditions dominated LIA, a typical "Westerly" pattern which is opposite to the hydrological variation in Asian monsoonal regions. Biomarker records' correlation with solar irradiance (SI), the North Atlantic Oscillation (NAO), the 1000year ACA Moisture Index (ACAM), and the North Hemisphere Temperature (NHT) suggests SI as one of the forcing factor on temperature fluctuation and cold and wet LIA possibly resulting from westerly-jet shift, negative NAO oscillation and the lower evaporation induced by the decrease of temperature. Biomarker records for the whole Holocene will be also presented.

  5. Automated recording of home cage activity and temperature of individual rats housed in social groups: The Rodent Big Brother project.

    Science.gov (United States)

    Redfern, William S; Tse, Karen; Grant, Claire; Keerie, Amy; Simpson, David J; Pedersen, John C; Rimmer, Victoria; Leslie, Lauren; Klein, Stephanie K; Karp, Natasha A; Sillito, Rowland; Chartsias, Agis; Lukins, Tim; Heward, James; Vickers, Catherine; Chapman, Kathryn; Armstrong, J Douglas

    2017-01-01

    Measuring the activity and temperature of rats is commonly required in biomedical research. Conventional approaches necessitate single housing, which affects their behavior and wellbeing. We have used a subcutaneous radiofrequency identification (RFID) transponder to measure ambulatory activity and temperature of individual rats when group-housed in conventional, rack-mounted home cages. The transponder location and temperature is detected by a matrix of antennae in a baseplate under the cage. An infrared high-definition camera acquires side-view video of the cage and also enables automated detection of vertical activity. Validation studies showed that baseplate-derived ambulatory activity correlated well with manual tracking and with side-view whole-cage video pixel movement. This technology enables individual behavioral and temperature data to be acquired continuously from group-housed rats in their familiar, home cage environment. We demonstrate its ability to reliably detect naturally occurring behavioral effects, extending beyond the capabilities of routine observational tests and conventional monitoring equipment. It has numerous potential applications including safety pharmacology, toxicology, circadian biology, disease models and drug discovery.

  6. Direct effects of temperature on forest nitrogen cycling revealed through analysis of long-term watershed records

    Science.gov (United States)

    E.N. Jack Brookshire; Stefan Gerber; Jackson R. Webster; James M. Vose; Wayne T. Swank

    2010-01-01

    The microbial conversion of organic nitrogen (N) to plant available forms is a critical determinant of plant growth and carbon sequestration in forests worldwide. In temperate zones, microbial activity is coupled to variations in temperature, yet at the ecosystem level, microbial N mineralization seems to play a minor role in determining patterns of N loss. Rather, N...

  7. Late Holocene temperature variability in Tasmania inferred from borehole temperature data

    Science.gov (United States)

    Suman, Asadusjjaman; Dyer, Fiona; White, Duanne

    2017-06-01

    Thirty-six borehole temperature-depth profiles were analysed to reconstruct the ground surface temperature history (GSTH) of eastern Tasmania for the past 5 centuries. We used the singular value decomposition method to invert borehole temperatures to produce temperature histories. The quality of borehole data was classified as high or low based on model misfit. The quality of the borehole data was not dependent on topography or land use. Analysis reveals that three to five high-quality borehole temperature-depth profiles were adequate to reconstruct robust paleotemperature records from any area. Average GSTH reconstructed from Tasmanian boreholes shows temperature increases about 1.2 ± 0.2 °C during the past 5 centuries. Reconstructed temperatures were consistent with meteorological records and other proxy records from Tasmania during their period of overlap. Temperature changes were greatest around the north-east coast and decreased towards the centre of Tasmania. The extension of the East Australian Current (EAC) further south and its strengthening around the north-east coast of Tasmania over the past century was considered a prime driver of warmer temperatures observed in north-east Tasmania.

  8. Workflows for intelligent monitoring using proxy services.

    Science.gov (United States)

    Rüping, Stefan; Wegener, Dennis; Sfakianakis, Stelios; Sengstag, Thierry

    2009-01-01

    Grid technologies have proven to be very successful in the area of eScience, and in particular in healthcare applications. But while the applicability of workflow enacting tools for biomedical research has long since been proven, the practical adoption into regular clinical research has some additional challenges in grid context. In this paper, we investigate the case of data monitoring, and how to seamlessly implement the step between a one-time proof-of-concept workflow and high-performance on-line monitoring of data streams, as exemplified by the case of long-running clinical trials. We will present an approach based on proxy services that allows executing single-run workflows repeatedly with little overhead.

  9. Salmon: Robust Proxy Distribution for Censorship Circumvention

    Directory of Open Access Journals (Sweden)

    Douglas Frederick

    2016-10-01

    Full Text Available Many governments block their citizens’ access to much of the Internet. Simple workarounds are unreliable; censors quickly discover and patch them. Previously proposed robust approaches either have non-trivial obstacles to deployment, or rely on low-performance covert channels that cannot support typical Internet usage such as streaming video. We present Salmon, an incrementally deployable system designed to resist a censor with the resources of the “Great Firewall” of China. Salmon relies on a network of volunteers in uncensored countries to run proxy servers. Although any member of the public can become a user, Salmon protects the bulk of its servers from being discovered and blocked by the censor via an algorithm for quickly identifying malicious users. The algorithm entails identifying some users as especially trustworthy or suspicious, based on their actions. We impede Sybil attacks by requiring either an unobtrusive check of a social network account, or a referral from a trustworthy user.

  10. Reconstructing Northeastern United States temperatures using Atlantic white cedar tree rings

    Science.gov (United States)

    Pearl, Jessie K.; Anchukaitis, Kevin J.; Pederson, Neil; Donnelly, Jeffrey P.

    2017-11-01

    Our knowledge of climate variability in the densely populated Northeastern United States is limited to instrumental data of the last century. Most regional paleoclimate proxies reflect a mix of climate responses, which makes reconstructing historical climate a challenge. Here we analyze tree-ring chronologies from Atlantic white cedar (Chamaecyparis thyoides) as a potential regional paleotemperature proxy. We evaluate our tree-ring network for spatiotemporal climate signal strength and reconstruction skill across New England. Atlantic white cedar sites in the northern section of the species’ range exhibit positive significant annual growth relationships with local and regional temperatures. Chronologies constructed from northern sites yield skillful reconstructions of temperature that reproduce centennial, multidecadal, and interannual variability in the instrumental record, providing a novel paleotemperature record for New England.

  11. Development of six PROMIS pediatrics proxy-report item banks

    Directory of Open Access Journals (Sweden)

    Irwin Debra E

    2012-02-01

    Full Text Available Abstract Background Pediatric self-report should be considered the standard for measuring patient reported outcomes (PRO among children. However, circumstances exist when the child is too young, cognitively impaired, or too ill to complete a PRO instrument and a proxy-report is needed. This paper describes the development process including the proxy cognitive interviews and large-field-test survey methods and sample characteristics employed to produce item parameters for the Patient Reported Outcomes Measurement Information System (PROMIS pediatric proxy-report item banks. Methods The PROMIS pediatric self-report items were converted into proxy-report items before undergoing cognitive interviews. These items covered six domains (physical function, emotional distress, social peer relationships, fatigue, pain interference, and asthma impact. Caregivers (n = 25 of children ages of 5 and 17 years provided qualitative feedback on proxy-report items to assess any major issues with these items. From May 2008 to March 2009, the large-scale survey enrolled children ages 8-17 years to complete the self-report version and caregivers to complete the proxy-report version of the survey (n = 1548 dyads. Caregivers of children ages 5 to 7 years completed the proxy report survey (n = 432. In addition, caregivers completed other proxy instruments, PedsQL™ 4.0 Generic Core Scales Parent Proxy-Report version, PedsQL™ Asthma Module Parent Proxy-Report version, and KIDSCREEN Parent-Proxy-52. Results Item content was well understood by proxies and did not require item revisions but some proxies clearly noted that determining an answer on behalf of their child was difficult for some items. Dyads and caregivers of children ages 5-17 years old were enrolled in the large-scale testing. The majority were female (85%, married (70%, Caucasian (64% and had at least a high school education (94%. Approximately 50% had children with a chronic health condition, primarily

  12. Preliminary TEX86 temperatures and a lake level record of tropical climate extremes derived from sediment cores and seismic stratigraphy from Lake Turkana, East Africa

    Science.gov (United States)

    Morrissey, A. J.; Scholz, C. A.; Russell, J. M.

    2012-12-01

    Lake Turkana is the largest lake in the Eastern Branch of the East African Rift System and records hydrologic conditions of a region spanning nearly 2.5 degrees of latitude (~2.0 - 4.5 degrees N) in the African tropics. New data suggest the Turkana region likely experienced much wetter and cooler climate over several intervals since the latest Pleistocene. Lake level was extremely low twice during the latest Pleistocene, evidenced by depositional hiatuses in high-resolution CHIRP seismic reflection data that correlate with sediments that have low water-content, abundant sand, and low total organic carbon (TOC as low as Lake Turkana, like many lakes in northern tropical Africa, had a wetter climate during the African Humid Period. Intervals of high lake levels (up to ~440 m amsl) are indicated by flat-lying, laterally continuous, low-amplitude reflections that correlate in sediment cores to dark, fine-grained, laminated sediment with high TOC (up to ~6%). Calcium carbonate accumulation during this time period is nearly 0%, and combined with evidence of laminated, unbioturbated sediment suggests a fresh, stratified lake with anoxic bottom waters. During the early mid-Holocene, lake level began to fall to close to present levels (~365 m amsl). Sediments deposited during this time period have low but variable organic carbon content (~0.5 - ~2%) and are much higher in inorganic carbon (from fine-grained calcite precipitation). A moderate lowstand during the late Holocene is indicated by an erosional unconformity seen down to ~40 m below the current lake surface in several seismic profiles. This record of lake level extremes suggests highly variable rainfall patterns, forced by migration of the Intertropical Convergence Zone) across tropical East Africa over the last 20,000 years. More than 50 sediment samples from 3 piston cores represent a continuous record of TEX86 temperature from ~20,000 years ago to modern. The generally low (lake surface temperature. The range of

  13. Use of a Blended Satellite and In situ Sea Surface Temperature Climate Data Record for Evaluating Long-term Impacts on Coral and Marine Mammal Communities

    Science.gov (United States)

    Banzon, P. V. F.; Liu, G.; Forney, K.; Becker, E.; Arzayus, K. M.; Sun, L.

    2016-02-01

    The NOAA ¼° daily Optimum Interpolation (OI) Sea Surface temperature (SST), an in situ and satellite-based climate data record of SST available from 1981, was used to examine potential impacts of long-term temperature change on marine ecosystems. As a benthic example, historical heat stress in key tropical coral reef regions was calculated from the daily temperature data, using the NOAA Coral Reef Watch methodology. The regions with long-term ocean warming trend and experiencing more frequent thermal stress are identified as the regions with high vulnerability. While corals may be able to adapt to slow changes, no systematic adaptation has been reported with temperature increase over the past few decades. In contrast to the attached corals, marine mammals respond to changes in their environment by changing their distributions, often over large geographic areas. Habitat-based species distribution models can be developed to predict changes in the spatial distribution and abundance of marine mammals. OISST is a good predictor of the distribution of some marine mammal species, including Bryde's whales, false killer whales, and striped dolphins, and SST-based distribution models provide a foundation for projecting potential impacts of future temperature changes on marine mammals. Preliminary results from some of our research activities will be presented.

  14. A compilation of Western European terrestrial records 60-8 ka BP: towards an understanding of latitudinal climatic gradients

    Science.gov (United States)

    Moreno, Ana; Svensson, Anders; Brooks, Stephen J.; Connor, Simon; Engels, Stefan; Fletcher, William; Genty, Dominique; Heiri, Oliver; Labuhn, Inga; Perşoiu, Aurel; Peyron, Odile; Sadori, Laura; Valero-Garcés, Blas; Wulf, Sabine; Zanchetta, Giovanni

    2014-12-01

    Terrestrial records of past climatic conditions, such as lake sediments and speleothems, provide data of great importance for understanding environmental changes. However, unlike marine and ice core records, terrestrial palaeodata are often not available in databases or in a format that is easily accessible to the non-specialist. As a consequence, many excellent terrestrial records are unknown to the broader palaeoclimate community and are not included in compilations, comparisons, or modelling exercises. Here we present a compilation of Western European terrestrial palaeo-records covering, entirely or partially, the 60-8-ka INTIMATE time period. The compilation contains 56 natural archives, including lake records, speleothems, ice cores, and terrestrial proxies in marine records. The compilation is limited to include records of high temporal resolution and/or records that provide climate proxies or quantitative reconstructions of environmental parameters, such as temperature or precipitation, and that are of relevance and interest to a broader community. We briefly review the different types of terrestrial archives, their respective proxies, their interpretation and their application for palaeoclimatic reconstructions. We also discuss the importance of independent chronologies and the issue of record synchronization. The aim of this exercise is to provide the wider palaeo-community with a consistent compilation of high-quality terrestrial records, to facilitate model-data comparisons, and to identify key areas of interest for future investigations. We use the compilation to investigate Western European latitudinal climate gradients during the deglacial period and, despite of poorly constrained chronologies for the older records, we summarize the main results obtained from NW and SW European terrestrial records before the LGM.

  15. A new computational approach to reduce the signal from continuously recording gravimeters for the effect of atmospheric temperature

    Science.gov (United States)

    Andò, Bruno; Carbone, Daniele

    2006-12-01

    The experience of several authors has shown that continuous measurements of the gravity field, accomplished through spring devices, are strongly affected by changes of the ambient temperature. The apparent, temperature-driven, gravity changes can be up to one order of magnitude higher than the expected changes of the gravity field. Since these effects are frequency-dependent and instrument-related, they must be removed through non-linear techniques and in a case-by-case fashion. Past studies have demonstrated the effectiveness of a Neuro-Fuzzy algorithm as a tool to reduce continuous gravity sequences for the effect of external temperature changes. In the present work, an upgraded version of this previously employed algorithm is tested against the signal from a gravimeter, which was installed in two different sites over consecutive 96-day and 163-day periods. The better performance of the new algorithm with respect to the previous one is proven. Besides, inferences about the site and/or seasonal dependence of the model structure are reported.

  16. He said, she said: The gender wage gap according to self and proxy reports in the Current Population Survey.

    Science.gov (United States)

    Reynolds, Jeremy; Wenger, Jeffrey B

    2012-03-01

    Roughly half the labor force data in the Current Population Survey (CPS) are provided by proxy respondents, and since 1979, men's reliance on proxies has dropped dramatically while women's reliance on proxies has increased. Few authors, however, have examined how combining these first-hand and second-hand reports may influence our understanding of long-term economic trends. We exploit the outgoing rotation group structure of the CPS by matching individual records one year apart, and we find that self-reported wages are higher than proxy-reported wages even after controlling for all time invariant characteristics. Furthermore, we find that changes in the use of proxy respondents by men and women since 1979 have made current estimates of the gender wage gap larger than they would have been without changes in reporting status. This suggests that the gender wage gap has closed more than previously estimated. We recommend that researchers combine self and proxy responses with great care, especially when analyzing time trends or making gender comparisons. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Evolution of the 2014-2015 sea surface temperature warming in the central west coast of Baja California, Mexico, recorded by remote sensing

    Science.gov (United States)

    Robinson, Carlos J.

    2016-07-01

    Extraordinarily warm sea surface temperatures were present in the California Current System during 2014-2015. In several locations surface waters temperature registered new record high in the recent time series. This study focuses in the evolution of the warming in the southern part of the California Current System (CCS), off the west coast of Baja California, Mexico. Analysis of monthly sea surface temperature (SST), sea level pressure, and wind speed as measured by satellite from January 1988 to December 2015 show that recent warming occurred during two distinct periods. From May 2014 to April 2015, SST warming was related to weak coastal winds not associated to El Niño. During this period occurred the longest sustained record of 15 months of negative wind anomalies in the series. A reduction of wind stress suggests a weakened coastal upwelling, and consequently, cold water not transported into the surface. The second process of warming occurred from September to December 2015, during a strong El Niño condition.

  18. Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria

    Science.gov (United States)

    Ilyashuk, Elena A.; Koinig, Karin A.; Heiri, Oliver; Ilyashuk, Boris P.; Psenner, Roland

    2011-01-01

    Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (TJuly) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000–8600 cal yr BP) TJuly of up to 8.5 °C, i.e. >4 °C above the modern (1977–2006) mean July temperature. The reconstruction reveals the so-called ‘8.2-ka cold event’ centered at ca 8250–8000 cal yr BP with temperatures ca 3 °C below the early-Holocene thermal maximum. Rather warm (ca 6 °C) and productive conditions prevailed during ca 7900–4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler TJuly. A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in TJuly at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with TJuly cooler than 4 °C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic TJuly estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional

  19. Holocene temperature variations at a high-altitude site in the Eastern Alps: a chironomid record from Schwarzsee ob Sölden, Austria.

    Science.gov (United States)

    Ilyashuk, Elena A; Koinig, Karin A; Heiri, Oliver; Ilyashuk, Boris P; Psenner, Roland

    2011-01-01

    Few well-dated, quantitative Holocene temperature reconstructions exist from high-altitude sites in the Central Eastern Alps. Here, we present a chironomid-based quantitative reconstruction of mean July air temperatures (T(July)) throughout the Holocene for a remote high-mountain lake, Schwarzsee ob Sölden, situated above the treeline at 2796 m a.s.l. in the Austrian Alps. Applying a chironomid-temperature inference model developed from lakes of the Alpine region to a high-resolution chironomid record from the lake provides evidence for early Holocene (ca 10000-8600 cal yr BP) T(July) of up to 8.5 °C, i.e. >4 °C above the modern (1977-2006) mean July temperature. The reconstruction reveals the so-called '8.2-ka cold event' centered at ca 8250-8000 cal yr BP with temperatures ca 3 °C below the early-Holocene thermal maximum. Rather warm (ca 6 °C) and productive conditions prevailed during ca 7900-4500 cal yr BP. The chironomid record suggests a climate transition between ca 5200 and 4500 cal yr BP to cooler T(July). A distinct cooling trend is evident from ca 4500 until ca 2500 cal yr BP. Thereafter, the study site experienced its coldest conditions (around 4 °C or less) throughout the rest of the Holocene, with the exception of the warming trend during the late 20th century. Beside other factors, the Northern Hemisphere summer insolation seems to be the major driving force for the long-term trends in T(July) at high altitudes in the Eastern Alps. Due to the extreme location of the lake and the limited temperature range represented by the applied calibration data set, the chironomid-based temperature reconstruction fails to track phases of the late-Holocene climatic history with T(July) cooler than 4 °C. Further chironomid-based palaeoclimate model and down-core studies are required to address this problem, provide more realistic T(July) estimates from undisturbed high-altitude lakes in the Alps, and extract a reliable regional

  20. Source-specific diatom lipid biomarkers as proxies for Arctic and Antarctic sea ice

    Science.gov (United States)

    Belt, Simon

    2016-04-01

    Sea ice plays a key role in controlling global climate due its influence over heat and gas exchange between the oceans and the atmosphere. In addition, sea ice exerts a strong influence over the absorption of incoming radiation at the ocean surface as a result of its high reflectivity or albedo. Driven, in part, by the recent dramatic changes to sea ice cover in both the Arctic and the Antarctic, the development of proxies for sea ice has received growing attention over the last 10 years or so. Amongst these, some so-called highly branched isoprenoid (HBI) lipid biomarkers have attracted considerable interest, not least, because they are derived from certain diatoms that reside and bloom within the sea ice matrix itself, thus providing a more direct indication of sea ice presence compared with some other proxies. The signature HBI sea proxies are a mono-unsaturated HBI (IP25) for the Arctic and a di-unsaturated HBI (C25:2) for the Antarctic, with different source organisms for each. Although the variability in sedimentary abundances of IP25 and C25:2 in Arctic and Antarctic sediments generally reflect the corresponding changes in sea ice conditions, a more complete picture of reconstructing sea ice conditions likely requires a multi-proxy approach involving, for example, other lipid biomarkers that serve as proxy measures of nearby open water conditions or sea surface temperature. By adoption of such an approach, a research strategy aimed at improving estimates of sea ice concentrations or better definitions of sea ice conditions (e.g. marginal ice zone, polynyas, permanent ice cover) represents the next stage in lipid-based sea ice proxy development. This presentation will focus on recent developments and future plans that involve a multi-proxy approach to improving sea ice reconstruction. An understanding of sources, ecology and environmental fate of various HBIs and other diatom lipids will likely be key in shaping the future direction of lipid-based sea ice