WorldWideScience

Sample records for indian ocean satellite

  1. Retrieval of sea surface air temperature from satellite data over Indian Ocean: An empirical approach

    Digital Repository Service at National Institute of Oceanography (India)

    Sathe, P.V.; Muraleedharan, P.M.

    the sea surface air temperature from satellite derived sea surface humidity in the Indian Ocean. Using the insitu data on surface met parameters collected on board O.R.V. Sagar Kanya in the Indian Ocean over a period of 15 years, the relationship between...

  2. On Some Aspects of Precipitation over Tropical Indian Ocean Using Satellite Data

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Sreejith, O.P.

    The annual and inter-annual variability of precipitation over the tropical Indian Ocean is studied for the period 1979–1997, using satellite data from a variety of sensors. The Climate Prediction Center Merged Analysis Precipitation (CMAP...

  3. Near-equatorial convective regimes over the Indian Ocean as revealed by synergistic analysis of satellite observations.

    Digital Repository Service at National Institute of Oceanography (India)

    Levy, G.; Geiss, A.; RameshKumar, M.R.

    We examine the organization and temporal evolution of deep convection in relation to the low level flow over the Indian Ocean by a synergistic analysis of several satellite datasets for wind, rainfall, Outgoing Longwave Radiation (OLR) and cloud...

  4. Air-sea interaction over the Indian Ocean during the two contrasting monsoon years 1987 and 1988 studied with satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Schluessel, P.

    The air-sea interaction processes over the tropical Indian Ocean region are studied using sea surface temperature data from the Advanced Very High Resolution Radiometer sensor onboard the NOAA series of satellites. The columnar water-vapour content...

  5. Modulation of the Ganges-Brahmaputra River Plume by the Indian Ocean Dipole and Eddies Inferred From Satellite Observations

    Science.gov (United States)

    Fournier, S.; Vialard, J.; Lengaigne, M.; Lee, T.; Gierach, M. M.; Chaitanya, A. V. S.

    2017-12-01

    The Bay of Bengal receives large amounts of freshwater from the Ganga-Brahmaputra (GB) river during the summer monsoon. The resulting upper-ocean freshening influences seasonal rainfall, cyclones, and biological productivity. Sparse in situ observations and previous modeling studies suggest that the East India Coastal Current (EICC) transports these freshwaters southward after the monsoon as an approximately 200 km wide, 2,000 km long "river in the sea" along the East Indian coast. Sea surface salinity (SSS) from the Soil Moisture Active Passive (SMAP) satellite provides unprecedented views of this peculiar feature from intraseasonal to interannual timescales. SMAP SSS has a 0.83 correlation and 0.49 rms-difference to 0-5 m in situ measurements. SMAP and in stu data both indicate a SSS standard deviation of ˜0.7 to 1 away from the coast, that rises to 2 pss within 100 km of the coast, providing a very favorable signal-to-noise ratio in coastal areas. SMAP also captures the strong northern BoB, postmonsoon cross-shore SSS contrasts (˜10 pss) measured along ship transects. SMAP data are also consistent with previous modeling results that suggested a modulation of the EICC/GB plume southward extent by the Indian Ocean Dipole (IOD). Remote forcing associated with the negative Indian Ocean Dipole in the fall of 2016 indeed caused a stronger EICC and "river in the sea" that extended by approximately 800 km further south than that in 2015 (positive IOD year). The combination of SMAP and altimeter data shows eddies stirring the freshwater plume away from the coast.Plain Language SummaryThe Bay of Bengal receives large quantity of freshwater from the Ganges-Brahmaputra river during the monsoon. The resulting low-salinity sea surface has strong implications for the regional climate and living marine resources. In situ observations are too sparse to provide salinity maps in this basin, even every 3 months. In contrast, the SMAP satellite provides maps at 40 km resolution

  6. Deep-sea ecosystems of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Koslow, J.A.

    are potential sites for hydrothermal mineralization and contain active vent fields. There are no available estimates for the numbers of seamounts in the Indian Ocean based on echo sounder recordings. Satellite altimetry data indicate that the Indian Ocean has...

  7. Indian Ocean Rim Cooperation

    DEFF Research Database (Denmark)

    Wippel, Steffen

    Since the mid-1990s, the Indian Ocean has been experiencing increasing economic cooperation among its rim states. Middle Eastern countries, too, participate in the work of the Indian Ocean Rim Association, which received new impetus in the course of the current decade. Notably Oman is a very active...

  8. Satellite Ocean Heat Content Suite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This collection contains an operational Satellite Ocean Heat Content Suite (SOHCS) product generated by NOAA National Environmental Satellite, Data, and Information...

  9. Effect of tropical cyclones on the stratosphere–troposphere exchange observed using satellite observations over the north Indian Ocean

    Directory of Open Access Journals (Sweden)

    M. Venkat Ratnam

    2016-07-01

    Full Text Available Tropical cyclones play an important role in modifying the tropopause structure and dynamics as well as stratosphere–troposphere exchange (STE processes in the upper troposphere and lower stratosphere (UTLS region. In the present study, the impact of cyclones that occurred over the north Indian Ocean during 2007–2013 on the STE processes is quantified using satellite observations. Tropopause characteristics during cyclones are obtained from the Global Positioning System (GPS radio occultation (RO measurements, and ozone and water vapour concentrations in the UTLS region are obtained from Aura Microwave Limb Sounder (MLS satellite observations. The effect of cyclones on the tropopause parameters is observed to be more prominent within 500 km of the centre of the tropical cyclone. In our earlier study, we observed a decrease (increase in the tropopause altitude (temperature up to 0.6 km (3 K, and the convective outflow level increased up to 2 km. This change leads to a total increase in the tropical tropopause layer (TTL thickness of 3 km within 500 km of the centre of cyclone. Interestingly, an enhancement in the ozone mixing ratio in the upper troposphere is clearly noticed within 500 km from the cyclone centre, whereas the enhancement in the water vapour in the lower stratosphere is more significant on the south-east side, extending from 500 to 1000 km away from the cyclone centre. The cross-tropopause mass flux for different intensities of cyclones is estimated and it is found that the mean flux from the stratosphere to the troposphere for cyclonic storms is 0.05 ± 0.29 × 10−3 kg m−2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10−3 kg m−2. More downward flux is noticed on the north-west and south-west side of the cyclone centre. These results indicate that the cyclones have significant impact in effecting the tropopause structure, ozone and water vapour budget, and

  10. Zoogeography of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, T.S.S.

    The distribution pattern of zooplankton in the Indian Ocean is briefly reviewed on a within and between ocean patterns and is limited to species within a quite restricted sort of groups namely, Copepoda, Chaetognatha, Pteropoda and Euphausiacea...

  11. Oceanography of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Desai, B.N.

    This volume is an outcome of the presentation of selected 74 papers at the International Symposium on the Oceanography of the Indian Ocean held at National Institute of Oceanography during January 1991. The unique physical setting of the northern...

  12. Superficial mineral resources of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Siddiquie, H.N.; Hashimi, N.H.; Gujar, A; Valsangkar, A

    The sea floor of the Indian Ocean and the continental margins bordering the ocean are covered by a wide variety of terrigenous, biogenous and anthigenic mineral deposits. The biogenous deposits in the Indian Ocean comprise the corals on shallow...

  13. Indian Ocean surface winds from NCMRWF analysis as compared

    Indian Academy of Sciences (India)

    The quality of the surface wind analysis at the National Centre for Medium Range Weather Forecasts (NCMRWF), New Delhi over the tropical Indian Ocean and its improvement in 2001 are examined by comparing it with in situ buoy measurements and satellite derived surface winds from NASA QuikSCAT satellite (QSCT) ...

  14. Ocean tides for satellite geodesy

    Science.gov (United States)

    Dickman, S. R.

    1990-01-01

    Spherical harmonic tidal solutions have been obtained at the frequencies of the 32 largest luni-solar tides using prior theory of the author. That theory was developed for turbulent, nonglobal, self-gravitating, and loading oceans possessing realistic bathymetry and linearized bottom friction; the oceans satisfy no-flow boundary conditions at coastlines. In this theory the eddy viscosity and bottom drag coefficients are treated as spatially uniform. Comparison of the predicted degree-2 components of the Mf, P1, and M2 tides with those from numerical and satellite-based tide models allows the ocean friction parameters to be estimated at long and short periods. Using the 32 tide solutions, the frequency dependence of tidal admittance is investigated, and the validity of sideband tide models used in satellite orbit analysis is examined. The implications of admittance variability for oceanic resonances are also explored.

  15. Pseudofaults and associated seamounts in the conjugate Arabian and Eastern Somali basins, NW Indian Ocean- New constraints from high-resolution satellite-derived gravity data

    Digital Repository Service at National Institute of Oceanography (India)

    Sreejith, K.M.; Chaubey, A.K.; Mishra, A.; Kumar, S.; Rajawat, A.S.

    due to rifting between Seychelles and Laxmi Ridge-India and subsequent sea- floor spreading along paleo-Carlsberg Ridge since the Paleocene (magnetic Chron 28n, �63 Ma). The evolution of these two large conjugate ocean basins (Fig. 2) was dominated... by two major geo- Indian Ocean (Morgan, 1981; Duncan and Hargr the Indian plate moved over it. These tectonic e found impact on both the evolving conjugate o result, structural and tectonic elements of the ba Earlier studies suggest that oceanic...

  16. On some aspects of Indian Ocean warm pool

    Digital Repository Service at National Institute of Oceanography (India)

    Saji, P.K.; Balchand, A.N.; RameshKumar, M.R.

    Annual and interannual variation of Indian Ocean Warm Pool (IOWP) was studied using satellite and in situ ocean temperature data IOWP surface area undergoes a strong annual cycle attaining a maximum of 24x106km2 during April...

  17. Validation of satellite-derived tropical cyclone heat potential with in situ observations in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nagamani, P.V.; Ali, M.M.; Goni, G.J.; Dinezio, P.N.; Pezzullo, J.C.; UdayaBhaskar, T.V.S.; Gopalakrishna, V.V.; Nisha, K.

    validation with in situ estimations for quantification of their reliability and consistency. Once the validation has been carried out, the satellite-derived TCHP values with their improved tempo- ral and spatial properties can be conveniently used...

  18. On the role of sea surface temperature variability over the Tropical Indian Ocean in relation to summer monsoon using satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Muraleedharan, P.M.; Sathe, P.V.

    shipping tained from the Physical Oceanography Data Archives Centre (PODAAC) of the Jet Propulsion Laboratory, U.S.A. We have excluded the data for the period July*Ocean Remote Sensing Section, National Institute of Oceanog- raphy, Dona Paula, Goa, India... and the central Indian Ocean are highly correlated with the mon-January 0.43 20.00002 April 0.54 20.00053 soon rainfall over the western and central parts of India July 0.44 20.04 during the same week. Based on 80 years of ship data October 0.18 20.00014 (1900...

  19. Ocean surface waves and winds over the north Indian Ocean from satellite altimeter - preliminary results of SAC-NIO joint project

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, A.; Rajkumar, R.; Gairola, R.M.; Gohil, B.S.; Vethamony, P.; Rao, L.V.G.

    the respective correlation coefficients. Preliminary results with limited processed data showed that the correlation coefficients are approximately 0.6. Sample maps of wave and wind (satellite derived) in 2.5 degrees x 2.5 degrees grids have been prepared...

  20. Seven year satellite observations of the mean structures and variabilities in the regional aerosol distribution over the oceanic areas around the Indian subcontinent

    Directory of Open Access Journals (Sweden)

    S. K. Nair

    2005-09-01

    Full Text Available Aerosol distribution over the oceanic regions around the Indian subcontinent and its seasonal and interannual variabilities are studied using the aerosol optical depth (AOD derived from NOAA-14 and NOAA-16 AVHRR data for the period of November 1995–December 2003. The air-mass types over this region during the Asian summer monsoon season (June–September are significantly different from those during the Asian dry season (November–April. Hence, the aerosol loading and its properties over these oceanic regions are also distinctly different in these two periods. During the Asian dry season, the Arabian Sea and Bay of Bengal are dominated by the transport of aerosols from Northern Hemispheric landmasses, mainly the Indian subcontinent, Southeast Asia and Arabia. This aerosol transport is rather weak in the early part of the dry season (November–January compared to that in the later period (February–April. Large-scale transport of mineral dust from Arabia and the production of sea-salt aerosols, due to high surface wind speeds, contribute to the high aerosol loading over the Arabian Sea region during the summer monsoon season. As a result, the monthly mean AOD over the Arabian Sea shows a clear annual cycle with the highest values occurring in July. The AOD over the Bay of Bengal and the Southern Hemisphere Indian Ocean also displays an annual cycle with maxima during March and October, respectively. The amplitude of the annual variation is the largest in coastal Arabia and the least in the Southern Hemisphere Indian Ocean. The interannual variability in AOD is the largest over the Southeast Arabian Sea (seasonal mean AOD varies from 0.19 to 0.42 and the northern Bay of Bengal (seasonal mean AOD varies from 0.24 to 0.39 during the February–April period and is the least over the Southern Hemisphere Indian Ocean. This study also investigates the altitude regions and pathways of dominant aerosol transport by combining the AOD distribution with

  1. Air sea exchange of fluxes and Indian monsoon from satellite data

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Pankajakshan, T.; Sundaram, S.

    Temperature (Reynolds), Sea Surface Wind Speed and Integrated water vapor (from SSMI sensor onboard DMSP satellite series), mean sea level pressure (from NCEP/NCAR reanalysis data). Evaporation zones are identified over the western tropical Indian Ocean where...

  2. Seasonal mixed layer heat balance of the southwestern tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Foltz, G.R.; Vialard, J.; PraveenKumar, B.; McPhaden, M.J.

    from a long-term moored buoy are used in conjunction with satellite, in situ, and atmospheric reanalysis datasets to analyze the seasonal mixed layer heat balance in the thermocline ridge region of the southwestern tropical Indian Ocean. This region...

  3. Pseudofaults and associated seamounts in the conjugate Arabian and Eastern Somali basins, NW Indian Ocean - New constraints from high-resolution satellite-derived gravity data

    Science.gov (United States)

    Sreejith, K. M.; Chaubey, A. K.; Mishra, Akhil; Kumar, Shravan; Rajawat, A. S.

    2016-12-01

    Marine gravity data derived from satellite altimeters are effective tools in mapping fine-scale tectonic features of the ocean basins such as pseudofaults, fracture zones and seamounts, particularly when the ocean basins are carpeted with thick sediments. We use high-resolution satellite-generated gravity and seismic reflection data to map boundaries of pseudofaults and transferred crust related to the Paleocene spreading ridge propagation in the Arabian and its conjugate Eastern Somali basins. The study has provided refinement in the position of previously reported pseudofaults and their spatial extensions in the conjugate basins. It is observed that the transferred crustal block bounded by inner pseudofault and failed spreading ridge is characterized by a gravity low and rugged basement. The refined satellite gravity image of the Arabian Basin also revealed three seamounts in close proximity to the pseudofaults, which were not reported earlier. In the Eastern Somali Basin, seamounts are aligned along NE-SW direction forming ∼300 km long seamount chain. Admittance analysis and Flexural model studies indicated that the seamount chain is isostatically compensated locally with Effective Elastic Thickness (Te) of 3-4 km. Based on the present results and published plate tectonic models, we interpret that the seamounts in the Arabian Basin are formed by spreading ridge propagation and are associated with pseudofaults, whereas the seamount chain in the Eastern Somali Basin might have probably originated due to melting and upwelling of upper mantle heterogeneities in advance of migrating/propagating paleo Carlsberg Ridge.

  4. Swell Propagation over Indian Ocean Region

    Directory of Open Access Journals (Sweden)

    Suchandra A. Bhowmick

    2011-06-01

    Full Text Available Swells are the ocean surface gravity waves that have propagated out of their generating fetch to the distant coasts without significant attenuation. Therefore they contain a clear signature of the nature and intensity of wind at the generation location. This makes them a precursor to various atmospheric phenomena like distant storms, tropical cyclones, or even large scale sea breeze like monsoon. Since they are not affected by wind once they propagate out of their generating region, they cannot be described by regional wave models forced by local winds. However, their prediction is important, in particular, for ship routing and off shore structure designing. In the present work, the propagation of swell waves from the Southern Ocean and southern Indian Ocean to the central and northern Indian Ocean has been studied. For this purpose a spectral ocean Wave Model (WAM has been used to simulate significant wave height for 13 years from 1993–2005 using NCEP blended winds at a horizontal spatial resolution of 1° × 1°. It has been observed that Indian Ocean, with average wave height of approximately 2–3 m during July, is mostly dominated by swell waves generated predominantly under the extreme windy conditions prevailing over the Southern Ocean and southern Indian Ocean. In fact the swell waves reaching the Indian Ocean in early or mid May carry unique signatures of monsoon arriving over the Indian Subcontinent. Pre-monsoon month of April contains low swell waves ranging from 0.5–1 m. The amplitudes subsequently increase to approximately 1.5–2 meters around 7–15 days prior to the arrival of monsoon over the Indian Subcontinent. This embedded signature may be utilized as one of the important oceanographic precursor to the monsoon onset over the Indian Ocean.

  5. Western Indian Ocean Journal of Marine Science

    African Journals Online (AJOL)

    Western Indian Ocean Journal of Marine Science. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 3, No 2 (2004) >. Log in or Register to get access to full text downloads.

  6. Western Indian Ocean Journal of Marine Science

    African Journals Online (AJOL)

    Western Indian Ocean Journal of Marine Science. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 6, No 2 (2008) >. Log in or Register to get access to full text downloads.

  7. History of oceanography of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, R.

    This paper highlights history of the oceanography of the Indian Ocean. Oceanographic activities during Ancient period, Medieval period, British period, Post-Independence period are briefly discussed. The role of the IIOE, IOC, UNESCO are also...

  8. Ecosystem characterization in Indian Ocean sector, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Matondkar, S.G.P.; Dhargalkar, V.K.; Parulekar, A.H.

    is most pronounced, which makes Indian Ocean sector an upwelled area marked by high nutrients, appreciable growth rate of phytoplankton and rich organic matter in the water column. The fractionation studies revealed the importance of picoautotrophs...

  9. The Indian Ocean as a Connector

    Science.gov (United States)

    Durgadoo, J. V.; Biastoch, A.; Boning, C. W.

    2016-02-01

    The Indian Ocean is a conduit for the upper ocean flow of the global thermohaline circulation. It receives water from the Pacific Ocean through the Indonesian throughflow and the Tasman leakage, and exports water into the Atlantic by means of Agulhas leakage. A small contribution from the northern Indian Ocean is also detectable within Agulhas leakage. Changes on different timescales in the various components of the Pacific inflows and the Atlantic outflow have been reported. Little is known on the role of the Indian Ocean circulation in communicating changes from the Pacific into the Atlantic, let alone any eventual alterations in response to climate change. The precise routes and timescales of Indonesian throughflow, Tasman leakage, Red Sea and Persian Gulf Waters towards the Atlantic are examined in a Lagrangian framework within a high-resolution global ocean model. In this presentation, the following questions are addressed: How are Pacific waters modified in the Indian Ocean before reaching the Agulhas system? On what timescale is water that enters the Indian Ocean from the Pacific flushed out? How important are detours in the Bay of Bengal and Arabian Sea?

  10. Investigating the Indian Ocean Geoid Low

    Science.gov (United States)

    Ghosh, A.; Gollapalli, T.; Steinberger, B. M.

    2016-12-01

    The lowest geoid anomaly on Earth lies in the Indian Ocean just south of the Indian peninsula.Several theories have been proposed to explain this geoid low, most of which invoke past subduction. Some recent studies have alsoargued that high velocity anomalies in the lower mantle coupled with low velocity anomalies in the upper mantle are responsible for these negative geoidanomalies. However, there is no general consensus regarding the source of the Indian Ocean negative geoid. We investigate the source of this geoid low by using forward models of density driven mantle convection using CitcomS. We test various tomography models in our flow calculations with different radial and lateral viscosity variations. Many tomography modelsproduce a fairly high correlation to the global geoid, however none could match the precise location of the geoid low in the Indian Ocean. Amerged P-wave model of LLNL-G3DV3 in the Indian Ocean region and S40rts elsewhere yields a good fit to the geoid anomaly, both in pattern and magnitude.The source of this geoid low seems to stem from a low velocity anomaly stretching from a depth of 300 km up to 700 km in the northern Indian Ocean region.This velocity anomaly could potentially arise from material rising along the edge of the African LLSVP and moving towards the northeast, facilitated by the movementof the Indian plate in the same direction.

  11. Evaluation of radiative fluxes over the north Indian Ocean

    Science.gov (United States)

    Ramesh Kumar, M. R.; Pinker, Rachel T.; Mathew, Simi; Venkatesan, R.; Chen, W.

    2018-05-01

    Radiative fluxes are a key component of the surface heat budget of the oceans. Yet, observations over oceanic region are sparse due to the complexity of radiation measurements; moreover, certain oceanic regions are substantially under-sampled, such as the north Indian Ocean. The National Institute of Ocean Technology, Chennai, India, under its Ocean Observation Program has deployed an Ocean Moored Network for the Northern Indian Ocean (OMNI) both in the Arabian Sea and the Bay of Bengal. These buoys are equipped with sensors to measure radiation and rainfall, in addition to other basic meteorological parameters. They are also equipped with sensors to measure sub-surface currents, temperature, and conductivity from the surface up to a depth of 500 m. Observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard the National Aeronautics and Space Administration (NASA) AQUA and TERRA satellites have been used to infer surface radiation over the north Indian Ocean. In this study, we focus only on the shortwave (SW↓) fluxes. The evaluations of the MODIS-based SW↓ fluxes against the RAMA observing network have shown a very good agreement between them, and therefore, we use the MODIS-derived fluxes as a reference for the evaluation of the OMNI observations. In an early deployment of the OMNI buoys, the radiation sensors were placed at 2 m above the sea surface; subsequently, the height of the sensors was raised to 3 m. In this study, we show that there was a substantial improvement in the agreement between the buoy observations and the satellite estimates, once the sensors were raised to higher levels. The correlation coefficient increased from 0.87 to 0.93, and both the bias and standard deviations decreased substantially.

  12. Oceanic Precondition and Evolution of the Indian Ocean Dipole Events

    Science.gov (United States)

    Horii, T.; Masumoto, Y.; Ueki, I.; Hase, H.; Mizuno, K.

    2008-12-01

    Indian Ocean Dipole (IOD) is one of the interannual climate variability in the Indian Ocean, associated with the negative (positive) SST anomaly in the eastern (western) equatorial region developing during boreal summer/autumn seasons. Japan Agency for Marine-Earth Science and Technology (JAMSTEC) has been deploying TRITON buoys in the eastern equatorial Indian Ocean since October 2001. Details of subsurface ocean conditions associated with IOD events were observed by the mooring buoys in the eastern equatorial Indian Ocean in 2006, 2007, and 2008. In the 2006 IOD event, large-scale sea surface signals in the tropical Indian Ocean associated with the positive IOD started in August 2006, and the anomalous conditions continued until December 2006. Data from the mooring buoys, however, captured the first appearance of the negative temperature anomaly at the thermocline depth with strong westward current anomalies in May 2006, about three months earlier than the development of the surface signatures. Similar appearance of negative temperature anomalies in the subsurface were also observed in 2007 and 2008, while the amplitude, the timing, and the relation to the surface layer were different among the events. The implications of the subsurface conditions for the occurrences of these IOD events are discussed.

  13. Satellite-detected fluorescence reveals global physiology of ocean phytoplankton

    Directory of Open Access Journals (Sweden)

    M. J. Behrenfeld

    2009-05-01

    Full Text Available Phytoplankton photosynthesis links global ocean biology and climate-driven fluctuations in the physical environment. These interactions are largely expressed through changes in phytoplankton physiology, but physiological status has proven extremely challenging to characterize globally. Phytoplankton fluorescence does provide a rich source of physiological information long exploited in laboratory and field studies, and is now observed from space. Here we evaluate the physiological underpinnings of global variations in satellite-based phytoplankton chlorophyll fluorescence. The three dominant factors influencing fluorescence distributions are chlorophyll concentration, pigment packaging effects on light absorption, and light-dependent energy-quenching processes. After accounting for these three factors, resultant global distributions of quenching-corrected fluorescence quantum yields reveal a striking consistency with anticipated patterns of iron availability. High fluorescence quantum yields are typically found in low iron waters, while low quantum yields dominate regions where other environmental factors are most limiting to phytoplankton growth. Specific properties of photosynthetic membranes are discussed that provide a mechanistic view linking iron stress to satellite-detected fluorescence. Our results present satellite-based fluorescence as a valuable tool for evaluating nutrient stress predictions in ocean ecosystem models and give the first synoptic observational evidence that iron plays an important role in seasonal phytoplankton dynamics of the Indian Ocean. Satellite fluorescence may also provide a path for monitoring climate-phytoplankton physiology interactions and improving descriptions of phytoplankton light use efficiencies in ocean productivity models.

  14. Launching the First Indian Satellite

    Indian Academy of Sciences (India)

    materials and chemicals, rocket propulsion, satellite technology, control and guidance system, etc. ... entire country, especially the rural areas, and in the survey and management of natural resources. Listeners are no .... satellite will store the information over a longer period and then on command from the ground station at ...

  15. TSUNAMIGENIC SOURCES IN THE INDIAN OCEAN

    Directory of Open Access Journals (Sweden)

    B. K. Rastogi

    2008-01-01

    Full Text Available Based on an assessment of the repeat periods of great earthquakes from past seismicity, convergence rates and paleoseismological results, possible future source zones of tsunami generating earthquakes in the Indian Ocean (possible seismic gap areas are identified along subduction zones and zones of compression. Central Sumatra, Java, Makran coast, Indus Delta, Kutch-Saurashtra, Bangladesh and southern Myanmar are identified as possible source zones of earthquakes in near future which might cause tsunamis in the Indian Ocean, and in particular, that could affect India. The Sunda Arc (covering Sumatra and Java subduction zone, situated on the eastern side of the Indian Ocean, is one of the most active plate margins in the world that generates frequent great earthquakes, volcanic eruptions and tsunamis. The Andaman- Nicobar group of islands is also a seismically active zone that generates frequent earthquakes. However, northern Sumatra and Andaman-Nicobar regions are assessed to be probably free from great earthquakes (M!8.0 for a few decades due to occurrence of 2004 Mw 9.3 and 2005 Mw 8.7 earthquakes. The Krakatau volcanic eruptions have caused large tsunamis in the past. This volcano and a few others situated on the ocean bed can cause large tsunamis in the future. List of past tsunamis generated due to earthquakes/volcanic eruptions that affected the Indian region and vicinity in the Indian Ocean are also presented.

  16. Indian Ocean and Indian summer monsoon: relationships without ENSO in ocean-atmosphere coupled simulations

    Science.gov (United States)

    Crétat, Julien; Terray, Pascal; Masson, Sébastien; Sooraj, K. P.; Roxy, Mathew Koll

    2017-08-01

    The relationship between the Indian Ocean and the Indian summer monsoon (ISM) and their respective influence over the Indo-Western North Pacific (WNP) region are examined in the absence of El Niño Southern Oscillation (ENSO) in two partially decoupled global experiments. ENSO is removed by nudging the tropical Pacific simulated sea surface temperature (SST) toward SST climatology from either observations or a fully coupled control run. The control reasonably captures the observed relationships between ENSO, ISM and the Indian Ocean Dipole (IOD). Despite weaker amplitude, IODs do exist in the absence of ENSO and are triggered by a boreal spring ocean-atmosphere coupled mode over the South-East Indian Ocean similar to that found in the presence of ENSO. These pure IODs significantly affect the tropical Indian Ocean throughout boreal summer, inducing a significant modulation of both the local Walker and Hadley cells. This meridional circulation is masked in the presence of ENSO. However, these pure IODs do not significantly influence the Indian subcontinent rainfall despite overestimated SST variability in the eastern equatorial Indian Ocean compared to observations. On the other hand, they promote a late summer cross-equatorial quadrupole rainfall pattern linking the tropical Indian Ocean with the WNP, inducing important zonal shifts of the Walker circulation despite the absence of ENSO. Surprisingly, the interannual ISM rainfall variability is barely modified and the Indian Ocean does not force the monsoon circulation when ENSO is removed. On the contrary, the monsoon circulation significantly forces the Arabian Sea and Bay of Bengal SSTs, while its connection with the western tropical Indian Ocean is clearly driven by ENSO in our numerical framework. Convection and diabatic heating associated with above-normal ISM induce a strong response over the WNP, even in the absence of ENSO, favoring moisture convergence over India.

  17. Mediterranean climate change and Indian Ocean warming

    International Nuclear Information System (INIS)

    Hoerling, M.; Eischeid, J.; Hurrel, J.

    2006-01-01

    General circulation model (GCM) responses to 20. century changes in sea surface temperatures (SSTs) and greenhouse gases are diagnosed, with emphasis on their relationship to observed regional climate change over the Mediterranean region. A major question is whether the Mediterranean region's drying trend since 1950 can be understood as a consequence of the warming trend in tropical SSTs. We focus on the impact of Indian Ocean warming, which is itself the likely result of increasing greenhouse gases. It is discovered that a strong projection onto the positive polarity of the North Atlantic Oscillation (NAO) index characterizes the atmospheric response structure to the 1950-1999 warming of Indian Ocean SSTs. This influence appears to be robust in so far as it is reproduced in ensembles of experiments using three different GCMs. Both the equilibrium and transient responses to Indian Ocean warming are examined. Under each scenario, the latitude of prevailing mid latitude westerlies shifts poleward during the November-April period. The consequence is a drying of the Mediterranean region, whereas northern Europe and Scandinavia receive increased precipitation in concert with the poleward shift of storminess. The IPCC (TAR) 20. century coupled ocean-atmosphere simulations forced by observed greenhouse gas changes also yield a post-1950 drying trend over the Mediterranean. We argue that this feature of human-induced regional climate change is the outcome of a dynamical feedback, one involving Indian Ocean warming and a requisite adjustment of atmospheric circulation systems to such ocean warming

  18. High-resolution residual geoid and gravity anomaly data of the northern Indian Ocean - An input to geological understanding

    Digital Repository Service at National Institute of Oceanography (India)

    Sreejith, K.M.; Rajesh, S.; Majumdar, T.J.; Rao, G.S.; Radhakrishna, M.; Krishna, K.S.; Rajawat, A.S.

    ') geoid anomaly map of the northern Indian Ocean generated from the altimeter data obtained from Geodetic Missions of GEOSAT and ERS-1 along with ERS-2, TOPEX/POSIDEON and JASON satellites is presented. The geoid map of the Indian Ocean is dominated by a...

  19. Western Indian Ocean Journal of Marine Science - Vol 8, No 2 (2009)

    African Journals Online (AJOL)

    Eddy formation around South West Mascarene Plateau (Indian Ocean) as evidenced by satellite 'global ocean colour' data · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. MR Badal, SDDV Rughooputh, L Rydberg, IS Robinson, C Pattiaratchi.

  20. Archives: Western Indian Ocean Journal of Marine Science

    African Journals Online (AJOL)

    Items 1 - 29 of 29 ... Archives: Western Indian Ocean Journal of Marine Science. Journal Home > Archives: Western Indian Ocean Journal of Marine Science. Log in or Register to get access to full text downloads.

  1. Western Indian Ocean Journal of Marine Science: Journal ...

    African Journals Online (AJOL)

    Western Indian Ocean Journal of Marine Science: Journal Sponsorship. Journal Home > About the Journal > Western Indian Ocean Journal of Marine Science: Journal Sponsorship. Log in or Register to get access to full text downloads.

  2. New satellite altimetry products for coastal oceans

    Science.gov (United States)

    Dufau, Claire; Mercier, F.; Ablain, M.; Dibarboure, G.; Carrere, L.; Labroue, S.; Obligis, E.; Sicard, P.; Thibaut, P.; Birol, F.; Bronner, E.; Lombard, A.; Picot, N.

    Since the launch of Topex-Poseidon in 1992, satellite altimetry has become one of the most essential elements of the Earth's observing system. Its global view of the ocean state has permitted numerous improvements in the environment understanding, particularly in the global monitoring of climate changes and ocean circulation. Near the coastlines where human activities have a major impact on the ocean, satellite altimeter techniques are unfortunately limited by a growth of their error budget. This quality loss is due to land contamination in the altimetric and radiometric footprints but also to inaccurate geophysical corrections (tides, high-frequency processes linked to atmospheric forcing).Despite instrumental perturbations by emerged lands until 10 km (altimeter) and 50 km (radiometer) off the coasts, measurements are made and may contain useful information for coastal studies. In order to recover these data close to the coast, the French Spatial Agency (CNES) has funded the development of the PISTACH prototype dedicated to Jason-2 altimeter processing in coastal ocean. Since November 2008, these new satellite altimeter products have been providing new retracking solutions, several state-of-the-art or with higher resolution corrections in addition to standard fields. This presentation will present and illustrate this new set of satellite data for the coastal oceans.

  3. Seasonal Variability of Salt Transports in the Northern Indian Ocean

    Science.gov (United States)

    D'Addezio, J. M.; Bulusu, S.

    2016-02-01

    Due to limited observational data in the Indian Ocean compared to other regions of the global ocean, past work on the Northern Indian Ocean (NIO) has relied heavily upon model analysis to study the variability of regional salinity advection caused by the monsoon seasons. With the launch of the Soil Moisture and Ocean Salinity (SMOS) satellite in 2009 and the Aquarius SAC-D mission in 2011 (ended on June 7, 2011), remotely sensed, synoptic scale sea surface salinity (SSS) data is now readily available to study this dynamic region. The new observational data has allowed us to revisit the region to analyze seasonal variability of salinity advection in the NIO using several modeled products, the Aquarius and SMOS satellites, and Argo floats data. The model simulations include the Consortium for Estimating the Circulation and Climate of the Ocean (ECCO2), European Centre for Medium-Range Weather Forecasts - Ocean Reanalysis System 4 (ECMWF-ORSA4), Simple Ocean Data Assimilation (SODA) Reanalysis, and HYbrid Coordinate Ocean Model (HYCOM). Our analyses of salinity at the surface and at depths up to 200 m, surface salt transport in the top 5 m layer, and depth-integrated salt transports revealed different salinity processes in the NIO that are dominantly related to the semi-annual monsoons. Aquarius and SMOS prove useful tools for observing this dynamic region, and reveal some aspects of SSS that Argo cannot resolve. Meridional depth-integrated salt transports using the modeled products along 6°N revealed dominant advective processes from the surface towards near-bottom depths. Finally, a difference in subsurface salinity stratification causes many of the modeled products to incorrectly estimate the magnitude and seasonality of NIO barrier layer thickness (BLT) when compared to the Argo solution. This problem is also evident in model output from the Seychelles-Chagos Thermocline Ridge (SCTR), a region with strong air-sea teleconnections with the Arabian Sea.

  4. Launching the First Indian Satellite

    Indian Academy of Sciences (India)

    long run, this is not bad since it generates self-confidence and self-reliance - which in the final analysis are .... hopes to find some new X-ray sources. The second ... from the state of health of the satellite can be judged. A tracking network gives ...

  5. Upper ocean physical processes in the Tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, L.V.G.; Ram, P.S.

    This monograph is the outcome of an attempt by the authors to present a synthesis of the studies on physical processes in the Tropical Indian Ocean (TIO) in relation to air-sea interaction, monsoon/climate variability and biological productivity...

  6. Magnetically-driven oceans on Jovian satellites

    Science.gov (United States)

    Gissinger, C.; Petitdemange, L.

    2017-12-01

    During the last decade, data from Galileo space missions have added strong support for the existence of subsurface liquid oceans on several moons of Jupiter. For instance, it is now commonly accepted that an electrically conducting fluid beneath the icy crust of Europa's surface may explain the variations of the induced field measured near the satellite. These observations have raised many questions regarding the size and the salinity of such subsurface ocean, or how and why the water remains liquid. In addition, the hydrodynamics of such oceans is mostly unknown. These questions are of primary importance since Europa is often considered as a good candidate for the presence of life beyond the Earth. Here, we present the first numerical modeling of the rapidly-rotating magnetohydrodynamic (MHD) flow generated in Europa's interior: due to Jupiter's rotation with respect to Europa, we show that the Lorentz force induced by the time-varying Jovian magnetic field is able to generate an oceanic flow of a few km/h. Our results are understood in the framework of a simple theoretical model and we obtain a scaling law for the prediction of the mean oceanic velocity and the total heating generated inside the ocean of Europa. Finally, by comparing our simulations to Galileo observations, we make predictions on both the thickness and the electrical conductivity of the ocean of different Jovian's satellites.

  7. Indian Ocean experiments with a coupled model

    Energy Technology Data Exchange (ETDEWEB)

    Wainer, I. [Sao Paulo, Univ. (Brazil). Dept. of Oceanography

    1997-03-01

    A coupled ocean-atmosphere model is used to investigate the equatorial Indian Ocean response to the seasonally varying monsoon winds. Special attention is given to the oceanic response to the spatial distribution and changes in direction of the zonal winds. The Indian Ocean is surrounded by an Asian land mass to the North and an African land mass to the West. The model extends latitudinally between 41 N and 41 S. The asymmetric atmospheric model is driven by a mass source/sink term that is proportional to the sea surface temperature (SST) over the oceans and the heat balance over the land. The ocean is modeled using the Anderson and McCreary reduced-gravity transport model that includes a prognostic equation for the SST. The coupled system is driven by the annual cycle as manifested by zonally symmetric and asymmetric land and ocean heating. They explored the different nature of the equatorial ocean response to various patterns of zonal wind stress forcing in order to isolate the impact of the remote response on the Somali current. The major conclusions are : i) the equatorial response is fundamentally different for easterlies and westerlies, ii) the impact of the remote forcing on the Somali current is a function of the annual cycle, iii) the size of the basin sets the phase of the interference of the remote forcing on the Somali current relative to the local forcing.

  8. Satellite Ocean Biology: Past, Present, Future

    Science.gov (United States)

    McClain, Charles R.

    2012-01-01

    Since 1978 when the first satellite ocean color proof-of-concept sensor, the Nimbus-7 Coastal Zone Color Scanner, was launched, much progress has been made in refining the basic measurement concept and expanding the research applications of global satellite time series of biological and optical properties such as chlorophyll-a concentrations. The seminar will review the fundamentals of satellite ocean color measurements (sensor design considerations, on-orbit calibration, atmospheric corrections, and bio-optical algorithms), scientific results from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate resolution Imaging Spectroradiometer (MODIS) missions, and the goals of future NASA missions such as PACE, the Aerosol, Cloud, Ecology (ACE), and Geostationary Coastal and Air Pollution Events (GeoCAPE) missions.

  9. Nodules of the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Kodagali, V.N.

    of calcareous sediments within, and pelagic sediments south of 15 degrees S latitude Prior to the launching of the project, very little data was available on the Indian Ocean nodules compared to those of Pacific This chapter summaries the findings of the project...

  10. The warm pool in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Vinayachandran, P.N.; Shetye, S.R.

    is larger and warmer, a peculiarity of the pool in the Indian Ocean is its seasonal variation. The surface area of the pool changes from 24 x 106 km2 in April to 8 x 106 km2 in September due to interaction with the southwest monsoon. The annual cycles of sea...

  11. Western Indian Ocean Journal of Marine Science

    African Journals Online (AJOL)

    The Western Indian Ocean Journal of Marine Science (WIOJMS) provides an avenue for ... Effects of blood meal as a substitute for fish meal in the culture of juvenile Silver ... area of eastern Africa: the case of Quirimbas National Park, Mozambique ... This work is licensed under a Creative Commons Attribution 3.0 License.

  12. Satellite based Ocean Forecasting, the SOFT project

    Science.gov (United States)

    Stemmann, L.; Tintoré, J.; Moneris, S.

    2003-04-01

    The knowledge of future oceanic conditions would have enormous impact on human marine related areas. For such reasons, a number of international efforts are being carried out to obtain reliable and manageable ocean forecasting systems. Among the possible techniques that can be used to estimate the near future states of the ocean, an ocean forecasting system based on satellite imagery is developped through the Satelitte based Ocean ForecasTing project (SOFT). SOFT, established by the European Commission, considers the development of a forecasting system of the ocean space-time variability based on satellite data by using Artificial Intelligence techniques. This system will be merged with numerical simulation approaches, via assimilation techniques, to get a hybrid SOFT-numerical forecasting system of improved performance. The results of the project will provide efficient forecasting of sea-surface temperature structures, currents, dynamic height, and biological activity associated to chlorophyll fields. All these quantities could give valuable information on the planning and management of human activities in marine environments such as navigation, fisheries, pollution control, or coastal management. A detailed identification of present or new needs and potential end-users concerned by such an operational tool is being performed. The project would study solutions adapted to these specific needs.

  13. Indian Ocean warming modulates Pacific climate change.

    Science.gov (United States)

    Luo, Jing-Jia; Sasaki, Wataru; Masumoto, Yukio

    2012-11-13

    It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east-west Walker circulation) through the Pacific ocean-atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific's could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries.

  14. Atlantic and indian oceans pollution in africa

    Science.gov (United States)

    Abubakar, Babagana

    Africa is the second largest and most populated continent after Asia. Geographically it is located between the Atlantic and Indian Oceans. Most of the Africa's most populated and industrialized cities are located along the coast of the continent facing the Atlantic and Indian Oceans, example of such cities include Casablanca, Dakar, Accra, Lagos, Luanda and Cape town all facing the Atlantic Ocean and cities like East London, Durban, Maputo, Dar-es-salaam and Mogadishu are all facing the Indian Ocean. As a result of the geographical locations of African Coastal Cities plus increase in their population, industries, sea port operations, petroleum exploration activities, trafficking of toxic wastes and improper waste management culture lead to the incessant increase in the pollution of the two oceans. NATURE OF POLLUTION OF THE ATLANTIC OCEAN i. The petroleum exploration activities going on along the coast of "Gulf of Guinea" region and Angola continuously causes oil spillages in the process of drilling, bunkering and discharging of petroleum products in the Atlantic Ocean. ii. The incessant degreasing of the Sea Ports "Quay Aprons" along the Coastal cities of Lagos, Luanda, Cape Town etc are continuously polluting the Atlantic Ocean with chemicals. iii. Local wastes generated from the houses located in the coastal cities are always finding their ways into the Atlantic Ocean. NATURE OF POLLUTION OF THE INDIAN OCEAN i. Unlike the Atlantic ocean where petroleum is the major pollutant, the Indian Ocean is polluted by Toxic / Radioactive waste suspected to have been coming from the developed nations as reported by the United Nations Environmental Programme after the Tsunami disaster in December 2004 especially along the coast of Somalia. ii. The degreasing of the Quay Aprons at Port Elizabeth, Maputo, Dar-es-Salaam and Mongolism Sea Ports are also another major source polluting the Indian Ocean. PROBLEMS GENERATED AS A RESULT OF THE OCEANS POLLUTION i. Recent report

  15. Biophysical processes in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mc; Murtugudde, R.; Vialard, J.; Vinayachandran, P.N.; Wiggert, J.D.; Hood, R.R.; Shankar, D.; Shetye, S.R.

    Ocean Biogeochemical Processes and Ecological Variability Geophysical Monograph Series 185 Copyright 200� by the American Geophysical Union. 10.102�/2008GM000768 Biophysical Processes in the Indian Ocean J. P. McCreary, 1 R. Murtugudde, 2 J. Vialard, 3...) also plots the upper-layer thickness, h 1 , from the model of McCreary et al. [1��3] (hereinafter referred to as MKM); h 1 simulates the structure of the top of the actual thermocline reasonably well, except that it is somewhat too thin from 5...

  16. Indian Ocean warming modulates Pacific climate change

    Science.gov (United States)

    Luo, Jing-Jia; Sasaki, Wataru; Masumoto, Yukio

    2012-01-01

    It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east–west Walker circulation) through the Pacific ocean–atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific’s could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries. PMID:23112174

  17. Thorium content in bottom sediments of Pacific and Indian oceans

    International Nuclear Information System (INIS)

    Gurvich, E.G.; Lisitsyn, A.P.

    1980-01-01

    Presented are the results of 232 Th distribution study in different substance-genetic types of bottom sediments of Pacific and Indian oceans. Th content determination has been carried out by the method of instrumental neutron activation analysis. Th distribution maps in the surface layer of bottom sediments of Pacific and Indian oceans are drawn. It is noted that Indian ocean sediments are much richer with Th moreover Th distribution in different types of sediments is very non-uniform. Non-uniformity of Th distribution in different types of Pacific ocean sediments is considerably less than that of Indian ocean and exceeds it only in red oozes

  18. Validation of satellite derived LHF using coare_3.0 scheme and time series data over north-east Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Pankajakshan, T.; Sathe, P.V.

    to the scientific community as it call for near perfect observational platforms and sensors to Page 1 of 10Gayana (Concepción) - VALIDATION OF SATELLITE DERIVED LHF USING C... 8/11/2006http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717...>VALIDATION OF SATELLITE DERIVED LHF USING C... 8/11/2006http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382004000300019&lng=... Day and night passes of SSMI (wind speed and columnar water vapor) and TMI (sea surface temperature) data for the period July...

  19. Evidence for multiphase folding of the central Indian Ocean lithosphere

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Bull, J.M.; Scrutton, R.A.

    Long-wavelength (100-300 km) folding in the central Indian Ocean associated with the diffuse plate boundary separating the Indian, Australian, and Capricorn plates is Earth's most convincing example of organized large-scale lithospheric deformation...

  20. Inputs from Indian rivers to the ocean: A synthesis

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.; George, M.D.; SenGupta, R.

    ). Fluxes of chemical substances to the Indian Ocean from these rivers are computed to a first approximation. The major ion contents are inversely proportional to the river runoff especially for the rivers entering the Arabian Sea. On an average Indian...

  1. Interannual to Decadal SST Variability in the Tropical Indian Ocean

    Science.gov (United States)

    Wang, G.; Newman, M.; Han, W.

    2017-12-01

    The Indian Ocean has received increasing attention in recent years for its large impacts on regional and global climate. However, due mainly to the close interdependence of the climate variation within the Tropical Pacific and the Indian Ocean, the internal sea surface temperature (SST) variability within the Indian Ocean has not been studied extensively on longer time scales. In this presentation we will show analysis of the interannual to decadal SST variability in the Tropical Indian Ocean in observations and Linear Inverse Model (LIM) results. We also compare the decoupled Indian Ocean SST variability from the Pacific against fully coupled one based on LIM integrations, to test the factors influence the features of the leading SST modes in the Indian Ocean. The result shows the Indian Ocean Basin (IOB) mode, which is strongly related to global averaged SST variability, passively responses to the Pacific variation. Without tropical Indo-Pacific coupling interaction, the intensity of IOB significantly decreases by 80%. The Indian Ocean Dipole (IOD) mode demonstrates its independence from the Pacific SST variability since the IOD does not change its long-term characteristics at all without inter-basin interactions. The overall SSTA variance decreases significantly in the Tropical Indian Ocean in the coupling restricted LIM runs, especially when the one-way impact from the Pacific to the Indian Ocean is turned off, suggesting that most of the variability in the Indian Ocean comes from the Pacific influence. On the other hand, the Indian Ocean could also transport anomalies to the Pacific, making the interaction a complete two-way process.

  2. Carbon dioxide and nitrous oxide in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.; Naqvi, S.W.A; Jayakumar, D.A; George, M.D.; Narvekar, P.V.; DeSousa, S

    The understanding of biogeochemical cycling of carbon dioxide and nitrous oxide in the oceans is essential for predicting the fate of anthropogenically emitted components. The North Indian Ocean, with its diverse regimes, provides us with a natural...

  3. The diversity of Indian Ocean Heterotardigrada

    Directory of Open Access Journals (Sweden)

    Roberto SANDULLI

    2007-09-01

    Full Text Available Information about Indian Ocean tardigrades is quite scarce and in most cases refers to species in coastal coralline sediment and occasionally in abyssal mud. The present data concern species found in the intertidal sand of Coco and La Digue Islands in the Seychelles, previously unsampled for tardigrades, as well as species in subtidal sediment found at depths ranging between 1 and 60 m off the shores of the Maldive Atolls. These sediments are all very similar and consist of heterogeneous coralline sand, moderately or scarcely sorted. Sixteen species (three new to science were found in the Seychelles, belonging to Renaudarctidae, Stygarctidae, Halechiniscidae, Batillipedidae and Echiniscoididae. Diversity and evenness data are also interesting, with maximum values of H' = 2.59 and of J = 0.97. In the Maldives 25 species were found (two new to science belonging to Neostygarctidae, Stygarctidae, Halechiniscidae and Batillipedidae. Such a number of species, despite the low percentage of tardigrade fauna (only 0.6% of the total meiofauna, contributes to the high values of both diversity and evenness, with H' ranging between 1.5 and 2.6 and J between 0.6 and 1. The Indian Ocean tardigrade fauna currently numbers 31 species of Arthrotardigrada and 2 species of Echiniscoidida. In the present study, Arthrotardigrada are the most abundant and all the families are present except Neoarctidae. Halechiniscidae is present with all the sub-families (except Euclavartinae, thus contributing to the high diversity values. Furthermore, 18 species, representing more than 50% of the total marine tardigrade fauna, are new records for the Indian Ocean, including five species new to science.

  4. Role of tropical Indian and Atlantic Oceans variability on ENSO

    Science.gov (United States)

    Prodhomme, Chloé; Terray, Pascal; Masson, Sebastien; Boschat, Ghyslaine

    2014-05-01

    There are strong evidences of an interaction between tropical Indian, Atlantic and Pacific Oceans. Nevertheless, these interactions remain deeply controversial. While some authors claim the tropical Indian and Atlantic oceans only play a passive role with respect to ENSO, others suggest a driving role for these two basins on ENSO. The mecanisms underlying these relations are not fully understood and, in the Indian Ocean, the possible role of both modes of tropical variability (the Indian Ocean Dipole (IOD) and the Indian Ocean Basin mode (IOB)) remain unclear. To better quantify and understand how the variability of the tropical Indian and Atlantic Oceans impact ENSO variability, we performed two sensitivity experiments using the SINTEX-F2 coupled model. For each experiment, we suppressed the variability of SST and the air-sea coupling in either the tropical Indian Ocean or tropical Atlantic Ocean by applying a strong nudging of the SST to the observed SST climatology. In both experiments, the ENSO periodicity increases. In the Atlantic experiment, our understanding of this increased periodicity is drastically limited by the strongly biased mean state in this region. Conversely, in the Indian Ocean experiment, the increase of ENSO periodicity is related to the absence of the IOB following the El Niño peak, which leads to a decrease of westerly winds in the western Pacific during late winter and spring after the peak. These weaker westerlies hinders the transition to a La Niña phase and thus increase the duration and periodicity of the event.

  5. Recent Ship, Satellite and Autonomous Observations of Southern Ocean Eddies

    Science.gov (United States)

    Strutton, P. G.; Moreau, S.; Llort, J.; Phillips, H. E.; Patel, R.; Della Penna, A.; Langlais, C.; Lenton, A.; Matear, R.; Dawson, H.; Boyd, P. W.

    2016-12-01

    The Southern Ocean is the area of greatest uncertainty regarding the exchange of CO2 between the ocean and atmosphere. It is also a region of abundant energetic eddies that significantly impact circulation and biogeochemistry. In the Indian sector of the Southern Ocean, cyclonic eddies are unusual in that they are upwelling favorable, as for cyclonic eddies elsewhere, but during summer they are low in silicate and phytoplankton biomass. The reverse is true for anticyclonic eddies in that they have counter-intuitive positive chlorophyll anomalies in summer. Similar but less obvious patterns occur in the Pacific and Atlantic sectors. Using ship, satellite and autonomous observations in the region south of Australia, the physical and biogeochemical signatures of both types of eddies were documented in 2016. A cyclonic eddy that lived for seven weeks exhibited doming isopycnals indicative of upwelling. However, low surface silicate and chlorophyll concentrations appeared to be characteristic of surface waters to the south where the eddy formed. Higher chlorophyll was confined to filaments at the eddy edge. Surface nitrate and phosphate concentrations were more than sufficient for a bloom of non-siliceous phytoplankton to occur. Acoustic observations from a high resolution TRIAXUS transect through the eddy documented high zooplankton biomass in the upper 150m. It is hypothesized that a non-diatom bloom was prevented by grazing pressure, but light may have also been an important limiting resource in late summer (April). Two SOCCOM floats that were deployed in the eddy field continued to monitor the physics, nitrate and bio-optics through the transition to winter. These observations across complementary platforms have identified and then explained the reason for these unexpected biological anomalies in an energetic and globally important region of the global ocean. Understanding the role of eddies in this region will be critical to the representation of mesoscale

  6. Performance of the ocean state forecast system at Indian National Centre for Ocean Information Services

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, T.M.B.; Sirisha, P.; Sandhya, K.G.; Srinivas, K.; SanilKumar, V.; Sabique, L.; Nherakkol, A.; KrishnaPrasad, B.; RakhiKumari; Jeyakumar, C.; Kaviyazhahu, K.; RameshKumar, M.; Harikumar, R.; Shenoi, S.S.C.; Nayak, S.

    The reliability of the operational Ocean State Forecast system at the Indian National Centre for Ocean Information Services (INCOIS) during tropical cyclones that affect the coastline of India is described in this article. The performance...

  7. Seasonal variability of upper-layer geostrophic transport in the tropical Indian Ocean during 1992-1996 along TOGA-I XBT tracklines

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; Sarma, M.S.S.; Lambata, B.P.; Gopalakrishna, V.V.; Pednekar, S.M.; Rao, A.S.; Luis, A.J.; Kaka, A.R.; Rao, L.V.G.

    (2000) 1569}1582 1581 Subrahmanyam, B., 1998. A study of the Indian Ocean Circulation using satellite observations and model simulations. Ph.D. Thesis. University of Southampton, Department of Oceanography, UK., p. 251, unpublished. Suryanarayana, A...

  8. Bio-physical coupling and ocean dynamics in the central equatorial Indian Ocean during 2006 Indian Ocean Dipole

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; David, T.D.; Byju, P.; Narvekar, J.; Yoneyama, K.; Nakatani, N.; Ishida, A.; Horii, T.; Masumoto, Y.; Mizuno, K.

    an observational campaign MISMO (MIRAI Indian Ocean Cruise for the study of the MJO convection Onset) was conducted at equator and 80.5 0 E from Japanese research ship R/V Mirai during late October through November, 2006 when the onset in MJO convection is often...

  9. Air-Sea Coupling Over The Equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Gopika, N.

    S, where thermocline domes, the ocean is tightly coupled to the atmosphere [Reverdin, 1987; Murtugudde and Busalacchi, 1999; Xie et al, 2002] and therefore expected to influence the regional climate variability. In recent years Saji et al. [1999] showed... the forcing- response pattern of the ocean-atmosphere as a coupled system. For example, the anomalous ocean-atmosphere coupled phenomena like Indian Ocean Dipole mode produces anomalous atmospheric and oceanic condition that influence regional climate...

  10. Geochemical implications of gabbro from the slow-spreading Northern Central Indian Ocean Ridge, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, Dwijesh; Misra, S.; Banerjee, R.; Weis, D.

    ., 1989) and the dynamics of crystallization of plutonic rocks (Bloomer et al., 1989; Meyer et al., 1989). The recovery of gabbroic rocks is mostly restricted to major transform faults or fracture zones transecting mid-ocean ridges, e.g., Mid... gabbro of Indian Ocean Ridge System (Fig 1) is ODP leg 118 from SWIR (Dick et al., 2002; Coogan et al, 2001). Gabbro from Leg 179 (ODP Hole 735B from Atlantis II fracture zone, Dick et al., 2000) and Leg 179 (Hole 1105A) near Leg 118 have also been...

  11. Mineral resources of the Indian Ocean and related scientific research

    Digital Repository Service at National Institute of Oceanography (India)

    Siddiquie, H.N.; Gujar, A.R.; Hashimi, N.H.; Valsangkar, A.B.; Nath, B.N.

    The Indian Ocean (area: 74.917 x 106 km2, water volume: 291.945 x 106 km3, average depth: 3897 m) is the third largest of the world oceans. The lands bordering the ocean contain almost 40 percent of the world's population and contribute...

  12. Western Indian Ocean - A glimpse of the tectonic scenario

    Digital Repository Service at National Institute of Oceanography (India)

    Bhattacharya, G.C.; Chaubey, A.K.

    is the en echelon displacement of the NW-SE trending ridge axis by numerous NE-SW trending fracture Western Indian Ocean - A Glimpse of the Tectonic Scenario 693 Table 1. Some information from the scientific drilling campaigns in the western Indian Ocean...: Raman Seamount; P: Panikkar Seamount; W: Wadia Guyot; S: SagarKanya Seamount; SR: ShebaRidge; CR: Carlsberg Ridge; CIR: Central Indian Ridge; SWIR: Southwest Indian Ridge; RTJ: Rodrigues Triple Junction; OFZ: Owen Fracture Zone; LR: Laxmi Ridge; MR...

  13. Tropical Indian Ocean Variability Driving Southeast Australian Droughts

    Science.gov (United States)

    Ummenhofer, C. C.; England, M. H.; McIntosh, P. C.; Meyers, G. A.; Pook, M. J.; Risbey, J. S.; Sen Gupta, A.; Taschetto, A. S.

    2009-04-01

    Variability in the tropical Indian Ocean has widespread effects on rainfall in surrounding countries, including East Africa, India and Indonesia. The leading mode of tropical Indian Ocean variability, the Indian Ocean Dipole (IOD), is a coupled ocean-atmosphere mode characterized by sea surface temperature (SST) anomalies of opposite sign in the east and west of the basin with an associated large-scale atmospheric re-organisation. Earlier work has often focused on the positive phase of the IOD. However, we show here that the negative IOD phase is an important driver of regional rainfall variability and multi-year droughts. For southeastern Australia, we show that it is actually a lack of the negative IOD phase, rather than the positive IOD phase or Pacific variability, that provides the most robust explanation for recent drought conditions. Since 1995, a large region of Australia has been gripped by the most severe drought in living memory, the so-called "Big Dry". The ramifications for affected regions are dire, with acute water shortages for rural and metropolitan areas, record agricultural losses, the drying-out of two of Australia's major river systems and far-reaching ecosystem damage. Yet the drought's origins have remained elusive. For Southeast Australia, we show that the "Big Dry" and other iconic 20th Century droughts, including the Federation Drought (1895-1902) and World War II drought (1937-1945), are driven by tropical Indian Ocean variability, not Pacific Ocean conditions as traditionally assumed. Specifically, a conspicuous absence of characteristic Indian Ocean temperature conditions that are conducive to enhanced tropical moisture transport has deprived southeastern Australia of its normal rainfall quota. In the case of the "Big Dry", its unprecedented intensity is also related to recent above-average temperatures. Implications of recent non-uniform warming trends in the Indian Ocean and how that might affect ocean characteristics and climate in

  14. Multi-decadal modulation of the El Nino-Indian monsoon relationship by Indian Ocean variability

    International Nuclear Information System (INIS)

    Ummenhofer, Caroline C; Sen Gupta, Alexander; Li Yue; Taschetto, Andrea S; England, Matthew H

    2011-01-01

    The role of leading modes of Indo-Pacific climate variability is investigated for modulation of the strength of the Indian summer monsoon during the period 1877-2006. In particular, the effect of Indian Ocean conditions on the relationship between the El Nino-Southern Oscillation (ENSO) and the Indian monsoon is explored. Using an extended classification for ENSO and Indian Ocean dipole (IOD) events for the past 130 years and reanalyses, we have expanded previous interannual work to show that variations in Indian Ocean conditions modulate the ENSO-Indian monsoon relationship also on decadal timescales. El Nino events are frequently accompanied by a significantly reduced Indian monsoon and widespread drought conditions due to anomalous subsidence associated with a shift in the descending branch of the zonal Walker circulation. However, for El Nino events that co-occur with positive IOD (pIOD) events, Indian Ocean conditions act to counter El Nino's drought-inducing subsidence by enhancing moisture convergence over the Indian subcontinent, with an average monsoon season resulting. Decadal modulations of the frequency of independent and combined El Nino and pIOD events are consistent with a strengthened El Nino-Indian monsoon relationship observed at the start of the 20th century and the apparent recent weakening of the El Nino-Indian monsoon relationship.

  15. Multi-decadal modulation of the El Nino-Indian monsoon relationship by Indian Ocean variability

    Energy Technology Data Exchange (ETDEWEB)

    Ummenhofer, Caroline C; Sen Gupta, Alexander; Li Yue; Taschetto, Andrea S; England, Matthew H, E-mail: c.ummenhofer@unsw.edu.au [Climate Change Research Centre, University of New South Wales, Sydney (Australia)

    2011-07-15

    The role of leading modes of Indo-Pacific climate variability is investigated for modulation of the strength of the Indian summer monsoon during the period 1877-2006. In particular, the effect of Indian Ocean conditions on the relationship between the El Nino-Southern Oscillation (ENSO) and the Indian monsoon is explored. Using an extended classification for ENSO and Indian Ocean dipole (IOD) events for the past 130 years and reanalyses, we have expanded previous interannual work to show that variations in Indian Ocean conditions modulate the ENSO-Indian monsoon relationship also on decadal timescales. El Nino events are frequently accompanied by a significantly reduced Indian monsoon and widespread drought conditions due to anomalous subsidence associated with a shift in the descending branch of the zonal Walker circulation. However, for El Nino events that co-occur with positive IOD (pIOD) events, Indian Ocean conditions act to counter El Nino's drought-inducing subsidence by enhancing moisture convergence over the Indian subcontinent, with an average monsoon season resulting. Decadal modulations of the frequency of independent and combined El Nino and pIOD events are consistent with a strengthened El Nino-Indian monsoon relationship observed at the start of the 20th century and the apparent recent weakening of the El Nino-Indian monsoon relationship.

  16. Phytoplankton composition and biomass across the southern Indian Ocean

    DEFF Research Database (Denmark)

    Schlüter, Louise; Henriksen, Peter; Nielsen, Torkel Gissel

    2011-01-01

    prochlorophytes dominated at these two stations, but also pelagophytes, haptophytes and cyanobacteria were abundant. Haptophytes Type 6 (sensu Zapata et al., 2004), most likely Emiliania huxleyi, and pelagophytes were the dominating eucaryotes in the southern Indian Ocean. Prochlorophytes dominated...

  17. Climate of the northern Indian Ocean and associated productivity

    Digital Repository Service at National Institute of Oceanography (India)

    Sastry, J.S.; Gopinathan, C.K.

    The climatic factors likely to influence the phytoplankton production in the northern Indian Ocean are examined. The major cause for the high productivity of the Arabian Sea is the nutrient enrichment of the euphotic zone by upwelling especially off...

  18. Oceanographic data and information network in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sarupria, J.S.; Reddy, G.V.

    National Oceanographic Data Centres (RNODCs) and 3 World Data Centres (WDCs) for oceanographic data /information management and exchange. Regional data/information network in the Indian Ocean is being managed by 9 NODCs and 2 RNODCs and oceanographic...

  19. Calanoid copepods of the International Indian Ocean Expedition

    Digital Repository Service at National Institute of Oceanography (India)

    Stephen, R.; Devi, K.S.; Meenakshikunjamma, P.P.; Gopalakrishnan, T.C.; Saraswathy, M.

    The distribution of calanoid copepods is discussed based on the subsorted taxa of the International Indian Ocean Expedition samples. Of the 32 calanoid taxa only 17 groups were considered as significant components. The family Eycalanidae...

  20. Alteration of basaltic glasses from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.

    Textural, mineralogical and compositional characteristics of basaltic glasses from the Central Indian Ocean show them to be altered to varying extents through their interaction with the seawater, resulting in the formation of palagonite. The major...

  1. Drift pumice in the central Indian Ocean Basin: Geochemical evidence

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Mudholkar, A.V.; JaiSankar, S.; Ilangovan, D.

    Abundant white to light grey-coloured pumice without ferromanganese oxide coating occurs within the Quaternary sediments of the Central Indian Ocean Basin (CIOB). Two distinct groups of pumice are identified from their geochemical composition, which...

  2. Development of manganese nodule resources in the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, R.

    Resources evalution on grade and abundance of nodules using statistical methods for grab samples and photography data, combined with bathymetric and structural mapping, were carried out for delineation of the potential area of Central Indian Ocean...

  3. India's manganese nodule mine site in the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.

    This commentary highlights the activities of massive exploration programme for manganese nodule deposits in the Central Indian Basin located 5 km below the ocean surface and India's claim for mine site development and registration with UNCLOS...

  4. Ferromanganese nodules from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Jauhari, P.; Pattan, J.N.

    In order to delineate a mine site for ferromanganese nodules, extensive surveys were conducted in Central Indian Ocean Basin. Mapping of the basin by multibeam swath bathymetry (Hydrosweep) has revealed many new bottom relief features...

  5. Chemical oceanography of the Indian Ocean, North of the equator

    Digital Repository Service at National Institute of Oceanography (India)

    SenGupta, R.; Naqvi, S.W.A.

    Chemical oceanographic studies in the North Indian Ocean have revealed several interesting and unique features. Dissolved oxygen northern boundary, prevents quick renewal of subsurface reducing conditions prevail at intermediate depths (ca. 150...

  6. Organochlorine pesticide residues in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shailaja, M.S.; Sarkar, A.

    periodic monitoring of the levels of the major pollutants. One on-going exercise has been to evaluate, qualitatively and quantitatively, the persistent organochlorine pesticide residues in the Northern Indian Ocean. The baseline levels of some...

  7. Stratification of zooplankton in the northwestern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Paulinose, V.T.; Gopalakrishnan, T.C.; Nair, K.K.C.; Aravindakshan, P.N.

    Study on stratification of zooplankton in the north western Indian Ocean was carried out with special reference to its relative abundance and distribution. Samples were collected using multiple plankton net, during first cruise of ORV Sagar Kanya...

  8. Intraseasonal meridional current variability in the eastern equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ogata, T.; Sasaki, H.; Murty, V.S.N.; Sarma, M.S.S.; Masumoto, Y.

    . [2007] demonstrate the possibility of the air-sea interac- tion in the eastern Indian Ocean at the intraseasonal time- scale by analyzing observed and simulated data. Recent studies also reveal that multiscale air-sea interactions be- tween intraseasonal...

  9. Western Indian Ocean Journal of Marine Science: Submissions

    African Journals Online (AJOL)

    Already have a Username/Password for Western Indian Ocean Journal of Marine Science? ... Editorial Policy ... The manuscript is your own original work, and does not duplicate any other previously published work, including your own ...

  10. Distribution of pelagic harpacticoid copepods from the Indian ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Haridas, P.; Rao, T.S.S.

    Pelagic harpacticoid copepods have been studied from the International Indian Ocean Expedition collections. Macrosetella gracilis and Miracia efferata were the most common species of harpacticoids with high densities near land masses. Other three...

  11. Bothid larvae (Pleuronectiformes-Pisces) of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, C.B.L.

    the Indian Ocean, their regional, seasonal as well as diurnal variations. Engyprosopon grandisquamis dominated contributing to 23.2% of the total larvae. Numerically the incidence of bothid larvae suggested a uniform pattern of distribution during the two...

  12. WATER TEMPERATURE and Other Data From Indian Ocean from 19760222 to 19910407 (NODC Accession 9400146)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The primary productivity and biological data in this accession were collected in the Indian Ocean by the Indian Ocean Data Center. Data was collected between...

  13. Interannual variability of the tropical Indian Ocean mixed layer depth

    Digital Repository Service at National Institute of Oceanography (India)

    Keerthi, M.G.; Lengaigne, M.; Vialard, J.; Montegut, C.deB.; Muraleedharan, P.M.

    , shoaling the MLD (Masson et al. 2002, Qu and Meyers 2005, Du et al. 2005). The seasonal cycle in the southern tropical Indian Ocean has been less 3 investigated. Seasonal shoaling and deepening of the mixed layer in the south-western Tropical Indian...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  15. The Second International Indian Ocean Expedition (IIOE-2)

    Science.gov (United States)

    Cowie, Greg; Hood, Raleigh

    2015-04-01

    The International Indian Ocean Expedition (IIOE) was one of the greatest international, interdisciplinary oceanographic research efforts of all time. Planning for the IIOE began in 1959 and the project officially continued through 1965, with forty-six research vessels participating under fourteen different flags. The IIOE motivated an unprecedented number of hydrographic surveys (and repeat surveys) over the course of the expedition covering the entire Indian Ocean basin. And it was an interdisciplinary endeavor that embraced physical oceanography, chemical oceanography, meteorology, marine biology, marine geology and geophysics. The end of 2015 will mark the 50th Anniversary of the completion of the IIOE. SCOR and the IOC are working to stimulate a new phase of coordinated international research focused on the Indian Ocean for a 5-year period beginning in late 2015 and continuing through 2020. The goal is to help to organize ongoing research and stimulate new initiatives in the 2015-2020 time frame as part of a larger expedition. Several International programs that have research ongoing or planned in the Indian Ocean during this time period and many countries are planning cruises in this time frame as well. These programs and national cruises will serve as a core for the new Indian Ocean research focus, which has been dubbed "IIOE-2." The overarching goal of the IIOE-2 is to advance our understanding of interactions between geological, oceanic and atmospheric processes that give rise to the complex physical dynamics of the Indian Ocean region, and to determine how those dynamics affect climate, extreme events, marine biogeochemical cycles, ecosystems and human populations. This understanding is required to predict the impacts of climate change, pollution, and increased fish harvesting on the Indian Ocean and its nations, as well as the influence of the Indian Ocean on other components of the Earth System. New understanding is also fundamental to policy makers for

  16. Introduced mammals on Western Indian Ocean islands

    Directory of Open Access Journals (Sweden)

    James C. Russell

    2016-04-01

    Full Text Available The diversity of introduced mammals and their introduction history varies greatly across the Western Indian Ocean (WIO islands, from ancient introductions in the past millennia on islands off the East coast of Africa where extant terrestrial native mammal communities exist, to very recent invasions in the past decades on islands in the Mascarene archipelago. We compile the distribution of 16 introduced mammal taxa on 28 island groups comprising almost 2000 islands. Through an exhaustive literature review and expert consultation process we recorded all mammal eradications, and species recoveries which could be attributed to introduced mammal eradication or control. All island groups have been invaded by mammals, and invasive cats and rats in particular are ubiquitous, but cultural contingency has also led to regional invasions by other mammals such as lemurs, civets and tenrecs. Mammal eradications have been attempted on 45 islands in the WIO, the majority in the Seychelles and Mauritius, and where successful have resulted in spectacular recovery of species and ecosystems. Invasive mammalian predator eradication or control in association with habitat management has led to improved conservation prospects for at least 24 species, and IUCN red-list down-listing of eight species, in the Mascarene Islands. Future island conservation prioritisation in the region will need to take account of global climate change and predicted sea-level rises and coastal inundation. Greater investment and prioritisation in island conservation in the region is warranted, given its high biodiversity values and the extent of invasions.

  17. Biodiversity of chaetognaths of the Andaman Sea, Indian Ocean.

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Gireesh, R.

    Andaman Sea is a prominent biodiversity hotspot in the Indian Ocean. Stratified zooplankton collections were taken at 33 locations during 2003-2006. Average density of chaetognaths was 8.5/msup(3) in open ocean and 41.6/m sup(3) in coastal waters...

  18. Liver lipids of Indian and Atlantic Ocean spinner Carcharhinus ...

    African Journals Online (AJOL)

    Shark liver oils are rich in polyunsaturated fatty acids, especially the n3 moieties. Data on the liver fatty acids of sharks from African waters, however, are limited. Liver samples from sharks from the western Indian Ocean off the east coast of South Africa and those from the Atlantic Ocean and Gulf of Mexico were examined.

  19. Time Series Observations in the North Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoy, D.M.; Naik, H.; Kurian, S.; Naqvi, S.W.A.; Khare, N.

    Ocean and the ongoing time series study (Candolim Time Series; CaTS) off Goa. In addition, this article also focuses on the new time series initiative in the Arabian Sea and the Bay of Bengal under Sustained Indian Ocean Biogeochemistry and Ecosystem...

  20. Cd, Zn, Ni and Cu in the Indian Ocean

    NARCIS (Netherlands)

    Saager, Paul M.; Baar, Hein J.W. de; Howland, Robin J.

    1992-01-01

    Vertical profiles of dissolved Cd, Zn, Ni and Cu in the Northwest Indian Ocean (Arabian Sea) exhibit a nutrient type distribution also observed in other oceans. The area is characterized by strong seasonal upwelling and a broad oxygen minimum zone in intermediate waters. However, neither Cd, Zn, Ni

  1. Deciphering Detailed Plate Kinematics of the Indian Ocean: A Combined Indian-Australian-French Initiative

    Science.gov (United States)

    Vadakkeyakath, Y.; Müller, R.; Dyment, J.; Bhattacharya, G.; Lister, G. S.; Kattoju, K. R.; Whittaker, J.; Shuhail, M.; Gibbons, A.; Jacob, J.; White, L. T.; Bissessur, P. D.; Kiranmai, S.

    2012-12-01

    The Indian Ocean formed as a result of the fragmentation and dispersal of East Gondwanaland since the Jurassic. The deep ocean basins in the Indian Ocean contain the imprints of this plate tectonic history, which is related with several major events such as the Kerguelen, Marion and Reunion hotspot inception and the Indo-Eurasian collision. A broad model for evolution of the Indian Ocean was proposed in the early 1980s. Subsequently, French scientists collected a large amount of magnetic data from the western and southern parts of the Indian Ocean while Indian and Australian scientists collected considerable volumes of magnetic data from the regions of Indian Ocean around their mainlands. Using these data, the Indian, French and Australian researchers independently carried out investigations over different parts of the Indian Ocean and provided improved models of plate kinematics at different sectoral plate boundaries. Under two Indo-French collaborative projects, detailed magnetic investigations were carried out in the Northwestern and Central Indian Ocean by combining the available magnetic data from conjugate regions. Those projects were complemented by additional area-specific studies in the Mascarene, Wharton, Laxmi and Gop basins, which are characterized by extinct spreading regimes. These Indo-French projects provided high resolution and improved plate tectonic models for the evolution of the conjugate Arabian and Eastern Somali basins that constrain the relative motion between the Indian-African (now Indian-Somalian) plate boundaries, and the conjugate Central Indian, Crozet and Madagascar basins that mainly constrain the relative motions of Indian-African (now Capricorn-Somalian) and Indian-Antarctic (now Capricorn-Antarctic) plate boundaries. During the same period, Australian scientists carried out investigations in the southeastern part of the Indian Ocean and provided an improved understanding of the plate tectonic evolution of the Indian

  2. IndOBIS, an Ocean Biogeographic Information System for assessment and conservation of Indian Ocean biodiversity

    Digital Repository Service at National Institute of Oceanography (India)

    Chavan, V.S.; Achuthankutty, C.T.; Berghe, E.V.; Wafar, M.V.M.

    Compilation of inventories of components of coastal and marine biodiversity of Indian Ocean is hampered by several factors: low effort by some countries, preference to certain taxon, dwindling taxonomic expertise, low infrastructure of Information...

  3. Anomalous intraseasonal events in the thermocline ridge region of Southern Tropical Indian Ocean and their regional impacts

    Science.gov (United States)

    Jayakumar, A.; Gnanaseelan, C.

    2012-03-01

    The present study explores the mechanisms responsible for the strong intraseasonal cooling events in the Thermocline Ridge region of the southwestern Indian Ocean. Air sea interface and oceanic processes associated with Madden Julian Oscillation are studied using an Ocean General Circulation Model and satellite observations. Sensitivity experiments are designed to understand the ocean response to intraseasonal forcing with a special emphasis on 2002 cooling events, which recorded the strongest intraseasonal perturbations during the last well-observed decade. This event is characterized by anomalous Walker circulation over the tropical Indian Ocean and persistent intraseasonal heat flux anomaly for a longer duration than is typical for similar events (but without any favorable preconditioning of ocean basic state at the interannual timescale). The model heat budget analysis during 1996 to 2007 revealed an in-phase relationship between atmospheric fluxes associated with Madden Julian Oscillation and the subsurface oceanic processes during the intense cooling events of 2002. The strong convection, reduced shortwave radiation and increased evaporation have contributed to the upper ocean heat loss in addition to the slower propagation of active phase of convection, which supported the integration of longer duration of forcing. The sensitivity experiments revealed that dynamic response of ocean through entrainment at the intraseasonal timescale primarily controls the biological response during the event, with oceanic interannual variability playing a secondary role. This study further speculates the role of oceanic intraseasonal variability in the 2002 droughts over Indian subcontinent.

  4. Metagenomic exploration of viruses throughout the Indian Ocean.

    Directory of Open Access Journals (Sweden)

    Shannon J Williamson

    Full Text Available The characterization of global marine microbial taxonomic and functional diversity is a primary goal of the Global Ocean Sampling Expedition. As part of this study, 19 water samples were collected aboard the Sorcerer II sailing vessel from the southern Indian Ocean in an effort to more thoroughly understand the lifestyle strategies of the microbial inhabitants of this ultra-oligotrophic region. No investigations of whole virioplankton assemblages have been conducted on waters collected from the Indian Ocean or across multiple size fractions thus far. Therefore, the goals of this study were to examine the effect of size fractionation on viral consortia structure and function and understand the diversity and functional potential of the Indian Ocean virome. Five samples were selected for comprehensive metagenomic exploration; and sequencing was performed on the microbes captured on 3.0-, 0.8- and 0.1 µm membrane filters as well as the viral fraction (<0.1 µm. Phylogenetic approaches were also used to identify predicted proteins of viral origin in the larger fractions of data from all Indian Ocean samples, which were included in subsequent metagenomic analyses. Taxonomic profiling of viral sequences suggested that size fractionation of marine microbial communities enriches for specific groups of viruses within the different size classes and functional characterization further substantiated this observation. Functional analyses also revealed a relative enrichment for metabolic proteins of viral origin that potentially reflect the physiological condition of host cells in the Indian Ocean including those involved in nitrogen metabolism and oxidative phosphorylation. A novel classification method, MGTAXA, was used to assess virus-host relationships in the Indian Ocean by predicting the taxonomy of putative host genera, with Prochlorococcus, Acanthochlois and members of the SAR86 cluster comprising the most abundant predictions. This is the first study

  5. Drift pumice in the Indian and South Atlantic oceans

    International Nuclear Information System (INIS)

    Frick, C.; Kent, L.E.

    1984-01-01

    Sixty-three samples of drift pumice, collected at the coasts of South Africa, East Africa, Madagascar, Mauritius, the Cocos Islands, Australia, Indonesia, Brazil, Marion Island and Bouvet Island, were investigated petrographically and geochemically with a view to establishing the possible source areas. Geochemically five distinct groups could be distinguished and some could be liked to specific eruptions in the Indian, Atlantic and Pacific oceans. Group A pumice originated from a submarine eruption off Zavodovski Island in the South Sandwich Island Group in 1962. The pumice in Group B occurs mainly on the beaches bordering the Atlantic Ocean, and was found on the west coast of South Africa, on the sea floor south-west of South Africa, and in Brazil. The source of this group is unknown, but all the evidence indicates that it must have been from the Mid-Atlantic Ridge in the South Atlantic Ocean. The Group C pumice was found in the southern Indian Ocean, probably from the Mid-Indian Ridge. The fourth group originated from a submarine eruption along the Tonga Trench in the Pacific Ocean. Group E, which is by far the most homogeneous, includes samples from Australia, the Indian Ocean islands, East and South Africa and samples of the undisputed Krakatoan origin. Specimens from the Krakatoan eruption are still the most abundant type of drift pumice that can be found

  6. Metallogenesis along the Indian Ocean Ridge System

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, R.; Ray, Dwijesh

    including India. Among these studies majority were concentrated around the Central Indian Ridge and the Southwest Indian Ridge areas, while a few observations were made around the rest of the areas in the IORS. The findings of these studies are discussed...

  7. West Nile virus infection in horses, Indian ocean.

    Science.gov (United States)

    Cardinale, E; Bernard, C; Lecollinet, S; Rakotoharinome, V M; Ravaomanana, J; Roger, M; Olive, M M; Meenowa, D; Jaumally, M R; Melanie, J; Héraud, J M; Zientara, S; Cêtre-Sossah, C

    2017-08-01

    The circulation of West Nile virus (WNV) in horses was investigated in the Southwest Indian ocean. In 2010, blood samples were collected from a total of 303 horses originating from Madagascar, Mauritius, Reunion and the Seychelles and tested for WNV-specific antibodies. An overall seroprevalence of 27.39% was detected in the Indian Ocean with the highest WNV antibody prevalence of 46.22% (95% CI: [37.4-55.2%]) in Madagascar. The age and origin of the horses were found to be associated with the WNV infection risk. This paper presents the first seroprevalence study investigating WN fever in horses in the Southwest Indian Ocean area and indicates a potential risk of infection for humans and animals. In order to gain a better understanding of WN transmission cycles, WNV surveillance needs to be implemented in each of the countries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Marine information technology - Indian Ocean scenario

    Digital Repository Service at National Institute of Oceanography (India)

    Nayak, M.R.; Gouveia, A.D.; Navelkar, G.S.; Singh, K.

    Marine and coastal information is necessary for sound decision making about sustainable utilisation of our oceanic and coastal resources. Due to inadequate data management tools, lack of information technology benefits in the minds of the ocean...

  9. Barrier spit recovery following the 2004 Indian Ocean tsunami at Pakarang Cape, southwest Thailand

    Science.gov (United States)

    Koiwa, Naoto; Takahashi, Mio; Sugisawa, Shuhei; Ito, Akifumi; Matsumoto, Hide-aki; Tanavud, Charlchai; Goto, Kazuhisa

    2018-04-01

    The 2004 Indian Ocean tsunami had notable impacts on coastal landforms. Temporal change in topography by coastal erosion and subsequent formation of a new barrier spit on the nearshore of Pakrang Cape, southeastern Thailand, had been monitored for 10 years since 2005 based on field measurement using satellite images, high-resolution differential GPS, and/or handy GPS. Monitored topography data show that a barrier island was formed offshore from the cape several months after the tsunami event through progradation of multiple elongated gravelly beach ridges and washover fan composed of coral gravels. Subsequently, the barrier spit expanded to the open sea. The progradation and expansion were supported by supply of a large amount of coral debris produced by the tsunami waves. These observations provide useful data to elucidate processes of change in coastal landforms after a tsunami event. The 2004 Indian Ocean tsunami played an important role in barrier spit evolution over a period of at least a decade.

  10. Temporal and spatial variability of phytoplankton pigment concentrations in the Indian Ocean, derived from the CZCS time series images

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available A total of 93 monthly global composite remotely sensed ocean color images from the Coastal Zone Color Scanner (CZCS on board the Nimbus-7 satellite were extracted for the Indian Ocean region (35ºN–55ºS; 30–120ºE to examine the seasonal variations in phytoplankton pigment concentrations, resulting from large-scale changes in physical oceanographic processes. The CZCS data sets were analyzed with the PC-SEAPAK software, and revealed large phytoplankton blooms in the northwest Arabian Sea and off the Somali coast. The blooms were triggered by wind-driven upwelling during the southwest monsoonal months of August and September. In the northern Arabian Sea, phytoplankton blooms, detected from January to March, appeared to be associated with nutrient enhancement resulting from winter convective mixing. In the Bay of Bengal, higher pigment concentrations were confined to the coastal regions but varied only marginally between seasons both in the coastal and offshore regions. Phytoplankton pigment concentrations were consistently low in the open Indian Ocean. Analysis of pigment concentrations extracted from the monthly-accumulated images revealed that the Arabian Sea sustained a greater biomass of phytoplankton compared with any other region of the Indian Ocean. Overall, the coastal regions of the Indian Ocean are richer in phytoplankton pigment than the open Indian Ocean. The number of images in individual areas was highly variable throughout the region due to varying cloud cover.

  11. The role stratification on Indian ocean mixing under global warming

    Science.gov (United States)

    Praveen, V.; Valsala, V.; Ravindran, A. M.

    2017-12-01

    The impact of changes in Indian ocean stratification on mixing under global warming is examined. Previous studies on global warming and associated weakening of winds reported to increase the stratification of the world ocean leading to a reduction in mixing, increased acidity, reduced oxygen and there by a reduction in productivity. However this processes is not uniform and are also modulated by changes in wind pattern of the future. Our study evaluate the role of stratification and surface fluxes on mixing focusing northern Indian ocean. A dynamical downscaling study using Regional ocean Modelling system (ROMS) forced with stratification and surface fluxes from selected CMIP5 models are presented. Results from an extensive set of historical and Representative Concentration Pathways 8.5 (rcp8.5) scenario simulations are used to quantify the distinctive role of stratification on mixing.

  12. Revealing climate modes in steric sea levels: lessons learned from satellite geodesy, objective analyses and ocean reanalyses

    Science.gov (United States)

    Pfeffer, J.; Tregoning, P.; Purcell, A. P.

    2017-12-01

    Due to increased greenhouse gases emissions, the oceans are accumulating heat. In response to the ocean circulation and atmospheric forcing, the heat is irregularly redistributed within the oceans, causing sea level to rise at variable rates in space and time. These rates of steric expansion are extremely difficult to assess because of the sparsity of in-situ hydrographic observations available within the course of the 20th century. We compare here three methods to reconstruct the steric sea levels over the past 13, 25 and 58 years based on satellite geodesy, objective analyses and ocean reanalyses. The interannual to decadal variability of each dataset is explored with a model merging six climate indices representative of the natural variability of the ocean and climate system. Consistent regional patterns are identified for the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO) in all datasets at all timescales. Despite the short time coverage (13 years), the combination of satellite geodetic data (altimetry and GRACE) also reveals significant steric responses to the North Pacific Gyre Oscillation (NPGO), Indian Dipole (IOD) and Indian ocean basinwide (IOBM) mode. The richer information content in the ocean reanalyses allows us to recover the regional fingerprints of the PDO, ENSO, NPGO, IOD and IOBM, but also of the Atlantic Multidecadal Oscillation (AMO) acting over longer time scales (40 to 60 years). Therefore, ocean reanalyses, coupled with climate mode analyses, constitute innovative and promising tools to investigate the mechanisms triggering the variability of sea level rise over the past decades.

  13. /sup 226/Ra in the western Indian Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Y.

    1987-09-01

    /sup 226/Ra profiles have been measured in the western Indian Ocean as part of the 1977-78 Indian Ocean GEOSECS program. These profiles show a general increase in deep and bottom water Ra concentration from the Circumpolar region to the Arabian Sea. A deep Ra maximum which originates in the Arabian Sea and in the Somali basin at about 3000 m depth spreads southward into the Mascarene basin and remains discernible in the Madagascar and Crozet basins. In the western Indian Ocean, the cold Antarctic Bottom Water spreads northward under the possibly southward-flowing deep water, forming a clear benthic front along the Crozet basin across the Southwest Indian Ridge into the Madagascar and Mascarene basins. The Antarctic Bottom Water continues to spread farther north to the Somali basin through the Amirante Passage at 10/sup 0/S as a western boundary current. The benthic front and other characteristic features in the western Indian Ocean are quite similar to those observed in the western Pacific where the benthic front as a distinctive feature was first described by Craig et al. Across the Mid-Indian Ridge toward the Ceylon abyssal plain near the triple junction, Ra profiles display a layered structure, reflecting the topographic effect of the mid-ocean ridge system on the mixing and circulation of the deep and bottom waters. Both Ra and Si show a deep maximum north of the Madagascar Basin. Linear relationships between these two elements are observed in the deep and bottom water with slopes increasing northward. This suggests a preferential input of Ra over Si from the bottom sediments of the Arabian Sea and also from the flank sediments of the Somali basin.

  14. Diurnal changes in ocean color sensed in satellite imagery

    Science.gov (United States)

    Arnone, Robert; Vandermuelen, Ryan; Soto, Inia; Ladner, Sherwin; Ondrusek, Michael; Yang, Haoping

    2017-07-01

    Measurements of diurnal changes in ocean color in turbid coastal regions in the Gulf of Mexico were characterized using above water spectral radiometry from a National Aeronautics and Space Administration (aerosol robotic network-WaveCIS CSI-06) site that can provide 8 to 10 observations per day. Satellite capability to detect diurnal changes in ocean color was characterized using hourly overlapping afternoon orbits of the visual infrared imaging radiometer suite (VIIRS) Suomi National Polar-orbiting Partnership ocean color sensor and validated with in situ observations. The monthly cycle of diurnal changes was investigated for different water masses using VIIRS overlaps. Results showed the capability of satellite observations to monitor hourly color changes in coastal regions that can be impacted by vertical movement of optical layers, in response to tides, resuspension, and river plume dispersion. The spatial variability of VIIRS diurnal changes showed the occurrence and displacement of phytoplankton blooming and decaying processes. The diurnal change in ocean color was above 20%, which represents a 30% change in chlorophyll-a. Seasonal changes in diurnal ocean color for different water masses suggest differences in summer and winter responses to surface processes. The diurnal changes observed using satellite ocean color can be used to define the following: surface processes associated with biological activity, vertical changes in optical depth, and advection of water masses.

  15. Understanding Rossby wave trains forced by the Indian Ocean Dipole

    Science.gov (United States)

    McIntosh, Peter C.; Hendon, Harry H.

    2018-04-01

    Convective variations over the tropical Indian Ocean associated with ENSO and the Indian Ocean Dipole force a Rossby wave train that appears to emanate poleward and eastward to the south of Australia and which causes climate variations across southern Australia and more generally throughout the Southern Hemisphere extratropics. However, during austral winter, the subtropical jet that extends from the eastern Indian Ocean into the western Pacific at Australian latitudes should effectively prohibit continuous propagation of a stationary Rossby wave from the tropics into the extratropics because the meridional gradient of mean absolute vorticity goes to zero on its poleward flank. The observed wave train indeed exhibits strong convergence of wave activity flux upon encountering this region of vanishing vorticity gradient and with some indication of reflection back into the tropics, indicating the continuous propagation of the stationary Rossby wave train from low to high latitudes is inhibited across the south of Australia. However, another Rossby wave train appears to emanate upstream of Australia on the poleward side of the subtropical jet and propagates eastward along the waveguide of the eddy-driven (sub-polar) jet into the Pacific sector of the Southern Ocean. This combination of evanescent wave train from the tropics and eastward propagating wave train emanating from higher latitudes upstream of Australia gives the appearance of a continuous Rossby wave train propagating from the tropical Indian Ocean into higher southern latitudes. The extratropical Rossby wave source on the poleward side of the subtropical jet stems from induced changes in transient eddy activity in the main storm track of the Southern Hemisphere. During austral spring, when the subtropical jet weakens, the Rossby wave train emanating from Indian Ocean convection is explained more traditionally by direct dispersion from divergence forcing at low latitudes.

  16. Biogeochemical studies of selenium in the Indian Ocean

    International Nuclear Information System (INIS)

    Hattori, H.; Nakaguchi, Y.; Hiraki, K.; Kimura, M.; Koike, Y.

    1999-01-01

    Selenium that is a one of trace essential elements exists mainly in the chemical form of Se(IV), Se(VI) and organic selenium in ocean. Moreover, the monitoring of the selenium species has become a matter of interest as a mean of estimating their influence in biological processes in ocean. In recent works, some investigators reported that Se(IV) shows nutrient-type especially like silica's behavior, Se(VI) shows an approximately constant value, and the biological activities control the distribution of organic selenium. However, these reports were not included the whole world's oceans. It is necessary to research several oceans for the explication of fate on selenium. We investigated at the most interesting area - the Eastern Indian Ocean where should play a key role in global ocean's cycle for acquiring the new knowledge of selenium species at first

  17. Role of sea surface wind stress forcing on transport between Tropical Pacific and Indian Ocean

    Science.gov (United States)

    Zhao, Q.

    Using an Indian-Pacific Ocean Circulation Model (IPOM) a simulation study on the Transports of between Tropical Pacific and Indian Ocean such as Indonesian Through flow (ITF) has been done. IPOM covered the area 25°E-70°W, 35°S-60°N. There are 31 levels in the vertical with 22 levels upper 400m in it. The horizontal resolution is 1/3° lat x 1.5° lon between 10°S and 10°N. The coastline and ocean topography of IPOM is prepared from Scripps topography data on 1x1°grid. Forcing IPOM with monthly observational wind stress in 1990-1999 the interannual variation of sea temperature has been reproduced well, not only on El Nino in the Pacific but also on Indian Ocean Dipole (IOD). Therefore, the oceanic circulations in the tropical ocean are reasonable. The analyses of the oceanic circulations from the simulations suggest that the transport southward through Makassar Strait is the primary route of thermocline water masses from the North Pacific to the Indonesian sea. The transport westward through Bali-Western Australian Transect (BWAT, at 117.5E) can be thought as the final output of ITF through the archipelago to Indian Ocean. The transport westward through BWAT is in 8-12S above 150m, its core centered near surface 10S, which looks like a jet. The westward velocity is more than 50 cm/s. The transport shows significant seasonal and interannual variations. The maximum is in Jul-Oct, minimum in Jan-Mar. These results are consistent with some observation basically. The correlation analyses indict that the variations of transport westward is related with the southeasterly anomaly in the east tropical Indian ocean. The transport variation lags wind anomaly about 3 months. The correlation coefficient is more than 0.6. The transport is strong during IOD, for example in 1994 and 1997. The variations are also related with the northwesterly anomaly in the center equatorial Pacific and the easterly in the eastern equatorial Pacific. The transport is strong in most ENSO

  18. Ocean transport and variability studies of the South Pacific, Southern, and Indian Oceans

    Science.gov (United States)

    Church, John A.; Cresswell, G. R.; Nilsson, C. S.; Mcdougall, T. J.; Coleman, R.; Rizos, C.; Penrose, J.; Hunter, J. R.; Lynch, M. J.

    1991-01-01

    The objectives of this study are to analyze ocean dynamics in the western South Pacific and the adjacent Southern Ocean and the eastern Indian Ocean. Specifically, our objectives for these three regions are, for the South Pacific Ocean: (1) To estimate the volume transport of the east Australian Current (EAC) along the Australian coast and in the Tasman Front, and to estimate the time variability (on seasonal and interannual time scales) of this transport. (2) To contribute to estimating the meridional heat and freshwater fluxes (and their variability) at about 30 deg S. Good estimates of the transport in the western boundary current are essential for accurate estimates of these fluxes. (3) To determine how the EAC transport (and its extension, the Tasman Front and the East Auckland Current) closes the subtropical gyre of the South Pacific and to better determine the structure at the confluence of this current and the Antarctic Circumpolar Current. (4) To examine the structure and time variability of the circulation in the western South Pacific and the adjacent Southern Ocean, particularly at the Tasman Front. For the Indian Ocean: (5) To study the seasonal interannual variations in the strength of the Leeuwin Current. (6) To monitor the Pacific-Indian Ocean throughflow and the South Equatorial and the South Java Currents between northwest Australia and Indonesia. (7) To study the processes that form the water of the permanent oceanic thermocline and, in particular, the way in which new thermocline water enters the permanent thermocline in late winter and early spring as the mixed layer restratifies. For the Southern Ocean: (8) To study the mesoscale and meridional structure of the Southern Ocean between 150 deg E and 170 deg E; in particular, to describe the Antarctic frontal system south of Tasmania and determine its interannual variability; to estimate the exchanges of heat, salt, and other properties between the Indian and Pacific Oceans; and to investigate the

  19. Composition of macrobenthos from the Central Indian Ocean Basin

    Indian Academy of Sciences (India)

    The deep sea is well known for its high faunal diversity. But the current interest in its abundant polymetallic nodules, poses a threat to the little known benthic organisms surviving in this unique environment. The present study is the first attempt to document the Indian Ocean abyssal benthic diversity of macroinvertebrates ...

  20. Behaviour and habitat of the Indian Ocean amphibious blenny ...

    African Journals Online (AJOL)

    Alticus monochrus Bleeker is an amphibious blenny that inhabits exposed and moderately exposed rocky shores of Mauritius and other islands of the southwestern Indian Ocean. It remains above the water line on moist or wet substrata over which it migrates vertically and/or horizontally with the tide. Rapid terrestrial ...

  1. Circulation of the surface waters in the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Varadachari, V.V.R.; Sharma, G.S.

    The circulation pattern of the surface waters in the North Indian Ocean for different months of the year is discussed. In order to arrive at a reliable and detailed picture of the circulation pattern, streamlines are drawn using the isogon technique...

  2. The influence of Indian Ocean Dipole (IOD) on biogeochemistry of ...

    Indian Academy of Sciences (India)

    Positive SST anomalies (SSTA) were found in the Arabian Sea (0.4 to 1.8 ... Keywords. Indian Ocean Dipole; biogeochemistry; carbon; chlorophyll; Arabian Sea; models. ... mainly control the strength of this source (Sarma ... of the CO2 evasion at the air–water interface (70 ..... tive SSHA due to asymmetric effect of upwelling.

  3. Ferromanganese oxides on sharks' teeth from Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Iyer, S.D.

    The mineralogy, composition and growth rates of ferromanganese (Fe-Mn) oxides over the sharks' teeth from the Central Indian Ocean Basin are presented. The trends of metal enrichment (Mn, Ni, Cu and Zn) and depletion (Fe and Co), the Mn/Fe ratio...

  4. Distribution of Bowen ratio over the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, G.R.L.; Rao, M.V.; Prasad, P.H.; Reddy, K.G.

    The monthly averages of Bowen ratio over the north Indian Ocean have been computed Three typical situations in the months of January May and September are taken for the present study Month to month differences in the Bowen ratio over the study...

  5. Macrofaunal diversity in the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pavithran, S.; Ingole, B.S.; Nanajkar, M.; Nath, B.N.

    to the increasing interest of mankind in the non-living resources and destructive deep-sea fishing practices present in these areas. The polymetallic nodule is one such resource, looked upon as an alternative to land-based minerals. The Central Indian Ocean Basin...

  6. Indian Ocean Networks and the Transmutations of Servitude

    DEFF Research Database (Denmark)

    Kaarsholm, Preben

    2016-01-01

    Focusing on Durban and its harbour, the article discusses the importation of different kinds of transnational bonded labour into Natal in the last half of the 19th century, and examines the ways in which Southern African and Indian Ocean histories were intertwined in the processes that built the ...

  7. Morphometric studies on a part of Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.

    Morphometric and slope angle studies carried out on a part of Indian Ocean Basin have shown that gentle slope angle ranges dominate, 92% of the area represented by 0-3 degrees slopes. Young's hypothesis of log-normal distribution of slope angle...

  8. Lithogenic fluxes to the northern Indian Ocean - An overview

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.

    Lithogenic fluxes to the northern Indian Ocean, measurEd. by time-series sediment traps, exhibit a strong seasonality with the bulk of the material (40 to 80 %) being deposited during the southwest monsoon period. This seasonality is more pronounced...

  9. Planktonic foraminifera from core tops of western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Guptha, M.V.S.

    distributional pattern showing upward trend in its abundance from 38 per cent at 21 degrees S latitude to 0.8 per cent at 6 degrees N latitude. Sub-tropical fauna is sparsely distributed in the Equatorial Indian Ocean. Based on these studies it is interpreted...

  10. Population Genetic Status of the Western Indian Ocean

    African Journals Online (AJOL)

    Abstract—Population genetics offers a useful technique for studying the population structure of marine organisms and has relevance to both systematics and the conservation of biodiversity. The Western Indian Ocean (WIO) is faced with increasing evidence of degradation and effective management initiatives are needed to ...

  11. Redefining Maritime Security Threats in the Eastern Indian Ocean Region.

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Arjun [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-08-01

    This occasional paper analyzes the general security issues and trends relating to maritime trafficking of radiological and nuclear material using small vessels, minor ports, and unchecked areas of coastline existing in the Eastern Indian Ocean Region today. By the Eastern Indian Ocean Region is meant the area starting from the tip of the Indian peninsula in the west to the Straits of Malacca in the east. It lays focus on the potential sources of nuclear or radiological material that may be trafficked here. It further undertakes a study of the terrorist groups active in the region as well as the multinational or national interdiction organizations that have been created to counter maritime threats. It also seeks to discern the various technologies for detecting materials of concern available in the area. Finally, it ascertains possible methods and technologies to improve the maritime security system in the region.

  12. Satellite tidal magnetic signals constrain oceanic lithosphere-asthenosphere boundary

    DEFF Research Database (Denmark)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation ofsecondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; howeve...

  13. Deciphering detailed plate kinematics of the Indian Ocean and developing a unified model for East Gondwanaland reconstruction: An Indian-Australian-French initiative

    Digital Repository Service at National Institute of Oceanography (India)

    Yatheesh, V.; Dyment, J.; Bhattacharya, G.C.; Muller, R.D.

    The Indian Ocean formed as a result of the fragmentation and dispersal of Gondwanaland since the Jurassic. The deep ocean basins in the Indian Ocean contain the imprints of this plate tectonic history, which is related with several major tectonic...

  14. Calibration of Ocean Forcing with satellite Flux Estimates (COFFEE)

    Science.gov (United States)

    Barron, Charlie; Jan, Dastugue; Jackie, May; Rowley, Clark; Smith, Scott; Spence, Peter; Gremes-Cordero, Silvia

    2016-04-01

    Predicting the evolution of ocean temperature in regional ocean models depends on estimates of surface heat fluxes and upper-ocean processes over the forecast period. Within the COFFEE project (Calibration of Ocean Forcing with satellite Flux Estimates, real-time satellite observations are used to estimate shortwave, longwave, sensible, and latent air-sea heat flux corrections to a background estimate from the prior day's regional or global model forecast. These satellite-corrected fluxes are used to prepare a corrected ocean hindcast and to estimate flux error covariances to project the heat flux corrections for a 3-5 day forecast. In this way, satellite remote sensing is applied to not only inform the initial ocean state but also to mitigate errors in surface heat flux and model representations affecting the distribution of heat in the upper ocean. While traditional assimilation of sea surface temperature (SST) observations re-centers ocean models at the start of each forecast cycle, COFFEE endeavors to appropriately partition and reduce among various surface heat flux and ocean dynamics sources. A suite of experiments in the southern California Current demonstrates a range of COFFEE capabilities, showing the impact on forecast error relative to a baseline three-dimensional variational (3DVAR) assimilation using operational global or regional atmospheric forcing. Experiment cases combine different levels of flux calibration with assimilation alternatives. The cases use the original fluxes, apply full satellite corrections during the forecast period, or extend hindcast corrections into the forecast period. Assimilation is either baseline 3DVAR or standard strong-constraint 4DVAR, with work proceeding to add a 4DVAR expanded to include a weak constraint treatment of the surface flux errors. Covariance of flux errors is estimated from the recent time series of forecast and calibrated flux terms. While the California Current examples are shown, the approach is

  15. Lagrangian analysis of multi-satellite data in support of open ocean Marine Protected Area design

    Science.gov (United States)

    Della Penna, Alice; Koubbi, Philippe; Cotté, Cedric; Bon, Cécile; Bost, Charles-André; d'Ovidio, Francesco

    2017-06-01

    Compared to ecosystem conservation in territorial seas, protecting the open ocean has peculiar geopolitical, economic and scientific challenges. One of the major obstacle is defining the boundary of an open ocean Marine Protected Area (MPA). In contrast to coastal ecosystems, which are mostly constrained by topographic structures fixed in time, the life of marine organisms in the open ocean is entrained by fluid dynamical structures like eddies and fronts, whose lifetime occurs on ecologically-relevant timescales. The position of these highly dynamical structures can vary interannually by hundreds of km, and so too will regions identified as ecologically relevant such as the foraging areas of marine predators. Thus, the expected foraging locations suggested from tracking data cannot be directly extrapolated beyond the year in which the data were collected. Here we explore the potential of Lagrangian methods applied to multisatellite data as a support tool for a MPA proposal by focusing on the Crozet archipelago oceanic area (Indian Sector of the Southern Ocean). By combining remote sensing with biologging information from a key marine top predator (Eudyptes chrysolophus, or Macaroni penguin) of the Southern Ocean foodweb, we identify a highly dynamic branch of the Subantarctic front as a foraging hotspot. By tracking this feature in historical satellite data (1993-2012) we are able to extrapolate the position of this foraging ground beyond the years in which tracking data are available and study its spatial variability.

  16. Dating of the 85 degrees E Ridge (northeastern Indian Ocean) using marine magnetic anomalies

    Digital Repository Service at National Institute of Oceanography (India)

    Michael, L.; Krishna, K.S.

    underneath the eastern Con- rad Rise on the Antarctic plate. Subsequent geophysical RESEARCH ARTICLES CURRENT SCIENCE, VOL. 100, NO. 9, 10 MAY 2011 1315 studies 5,8 opined that short-lived volcanic activity had ini- tiated the 85°E Ridge in Mahanadi.... Satellite-derived free-air gravity anomaly map of the north- eastern Indian Ocean 24 . Curved strip line indicates continuity of the 85°E Ridge from the Mahanadi Basin to ANS. Few bathymetry con- tours derived from ETOPO5 data are shown in the map. N...

  17. Apple - Indian experimental geostationary communication satellite

    Science.gov (United States)

    Rao, U. R.; Vasagam, R. M.

    Developmental steps, responsibilities, design goals, performance characteristics, and support systems for the ISRO Ariane Passenger Payload Experiment (APPLE) experimental GEO communication satellite are described. The spacecraft underwent structural, thermal, engineering, prototype, and flight qualification tests in India before being shipped to Guyana for launch on the third Ariane test flight. APPLE carries a redundant C-band communication transponder fed by a 900 mm diam parabolic reflector. A 6 GHz uplink and 4 GHz downlink are processed through a diplexer, with the receiver employing a low noise GaAs FET amplifier. In-orbit telemetry is provided by a 4095 MHz beacon with a data rate of 64 bits/sec. Two solar panels supply 210 W of power, while an on-board Ni-Cd storage battery stores 240 Wh for the ascent and during eclipse. Teleconferencing has been successfully performed using the spacecraft link.

  18. Ocean Optics Protocols for Satellite Ocean Color Sensor Validation. Revised

    Science.gov (United States)

    Fargion, Giulietta S.; Mueller, James L.

    2000-01-01

    The document stipulates protocols for measuring bio-optical and radiometric data for the Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities and algorithm development. This document supersedes the earlier version (Mueller and Austin 1995) published as Volume 25 in the SeaWiFS Technical Report Series. This document marks a significant departure from, and improvement on, theformat and content of Mueller and Austin (1995). The authorship of the protocols has been greatly broadened to include experts specializing in some key areas. New chapters have been added to provide detailed and comprehensive protocols for stability monitoring of radiometers using portable sources, abovewater measurements of remote-sensing reflectance, spectral absorption measurements for discrete water samples, HPLC pigment analysis and fluorometric pigment analysis. Protocols were included in Mueller and Austin (1995) for each of these areas, but the new treatment makes significant advances in each topic area. There are also new chapters prescribing protocols for calibration of sun photometers and sky radiance sensors, sun photometer and sky radiance measurements and analysis, and data archival. These topic areas were barely mentioned in Mueller and Austin (1995).

  19. Indian Ocean Dipole and El Niño/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean

    Directory of Open Access Journals (Sweden)

    J. C. Currie

    2013-10-01

    Full Text Available The Indian Ocean Dipole (IOD and the El Niño/Southern Oscillation (ENSO are independent climate modes, which frequently co-occur, driving significant interannual changes within the Indian Ocean. We use a four-decade hindcast from a coupled biophysical ocean general circulation model, to disentangle patterns of chlorophyll anomalies driven by these two climate modes. Comparisons with remotely sensed records show that the simulation competently reproduces the chlorophyll seasonal cycle, as well as open-ocean anomalies during the 1997/1998 ENSO and IOD event. Results suggest that anomalous surface and euphotic-layer chlorophyll blooms in the eastern equatorial Indian Ocean in fall, and southern Bay of Bengal in winter, are primarily related to IOD forcing. A negative influence of IOD on chlorophyll concentrations is shown in a region around the southern tip of India in fall. IOD also depresses depth-integrated chlorophyll in the 5–10° S thermocline ridge region, yet the signal is negligible in surface chlorophyll. The only investigated region where ENSO has a greater influence on chlorophyll than does IOD, is in the Somalia upwelling region, where it causes a decrease in fall and winter chlorophyll by reducing local upwelling winds. Yet unlike most other regions examined, the combined explanatory power of IOD and ENSO in predicting depth-integrated chlorophyll anomalies is relatively low in this region, suggestive that other drivers are important there. We show that the chlorophyll impact of climate indices is frequently asymmetric, with a general tendency for larger positive than negative chlorophyll anomalies. Our results suggest that ENSO and IOD cause significant and predictable regional re-organisation of chlorophyll via their influence on near-surface oceanography. Resolving the details of these effects should improve our understanding, and eventually gain predictability, of interannual changes in Indian Ocean productivity, fisheries

  20. Ocean sea-ice modelling in the Southern Ocean around Indian

    Indian Academy of Sciences (India)

    An eddy-resolving coupled ocean sea-ice modelling is carried out in the Southern Ocean region (9∘–78∘E; 51∘–71∘S) using the MITgcm. The model domain incorporates the Indian Antarctic stations, Maitri (11.7∘E; 70.7∘S) and Bharati (76.1∘E; 69.4∘S). The realistic simulation of the surface variables, namely, sea ...

  1. The Indian Ocean - An environmental overview

    Digital Repository Service at National Institute of Oceanography (India)

    SenGupta, R.; Qasim, S.Z.

    . Geographically, it is the area from 30 degrees S latitude to the Gulf of Oman and the head of the Bay of Bengal and from the East Africa coast to the coastlines of Burma, Thailand and Malaysia (excluding the Strait of Malacca). In this region of the Indain Ocean...

  2. The Chinese FY-1 Meteorological Satellite Application in Observation on Oceanic Environment

    Science.gov (United States)

    Weimin, S.

    meteorological satellite is stated in this paper. exploration of the ocean resources has been a very important question of global strategy in the world. The exploration of the ocean resources includes following items: Making full use of oceanic resources and space, protecting oceanic environment. to observe the ocean is by using of satellite. In 1978, US successfully launched the first ocean observation satellite in the world --- Sea Satellite. It develops ancient oceanography in to advanced space-oceanography. FY-1 B and FY- IC respectively. High quality data were acquired at home and abroad. FY-1 is Chinese meteorological satellite, but with 0.43 ~ 0.48 μm ,0.48 ~ 0.53 μm and 0.53 ~ 0.58 μm three ocean color channels, actually it is a multipurpose remote sensing satellite of meteorology and oceanography. FY-1 satellite's capability of observation on ocean partly, thus the application field is expanded and the value is increased. With the addition of oceanic channels on FY-1, the design of the satellite is changed from the original with meteorological observation as its main purpose into remote sensing satellite possessing capability of observing meteorology and ocean as well. Thus, the social and economic benefit of FY-1 is increased. the social and economic benefit of the development of the satellite is the key technique in the system design of the satellite. technically feasible but also save the funds in researching and manufacturing of the satellite, quicken the tempo of researching and manufacturing satellite. the scanning radiometer for FY-1 is conducted an aviation experiment over Chinese ocean. This experiment was of vital importance to the addition of oceanic observation channel on FY-1. FY-1 oceanic channels design to be correct. detecting ocean color. This is the unique character of Chinese FY-1 meteorological satellite. meteorological remote sensing channel on FY-1 to form detecting capability of three visible channels: red, yellow and blue

  3. Biogeochemical processes in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Gaye-Haake, B.; Guptha, M.V.S.; Murty, V.S.N.; Ittekkot, V.

    in the northern Indian Ocean’’, and from national research programs of India and Germany con- ducted as a contribution to the international JGOFS Process Study in the Arabian Sea. Addi- tional contributions cover research carried out within India’s Polymetallic... of coccolithophorids in addition to organic carbon and carbonate con- centrations and accumulation rates for a 200ka record Prabhu and Shankar show that glacial stages 2,4 and 6 have had higher productivities in the eastern Arabian Sea at about 151N. They, moreover...

  4. Mapping ocean tides with satellites - A computer simulation

    Science.gov (United States)

    Won, I. J.; Kuo, J. T.; Jachens, R. C.

    1978-01-01

    As a preliminary study for the future worldwide direct mapping of the open ocean tide with satellites equipped with precision altimeters we conducted a simulated study using sets of artificially generated altimeter data constructed from a realistic geoid and four pairs of major tides in the northeastern Pacific Ocean. Recovery of the original geoid and eight tidal maps is accomplished by a space-time, least squares harmonic analysis scheme. The resultant maps appear fairly satisfactory even when random noises up to + or - 100 cm are added to the altimeter data of sufficient space-time density. The method also produces a refined geoid which is rigorously corrected for the dynamic tides.

  5. Intraseasonal SST-precipitation coupling during the Indian Summer Monsoon, and its modulation by the Indian Ocean Dipole

    Science.gov (United States)

    Jongaramrungruang, S.; Seo, H.; Ummenhofer, C.

    2016-02-01

    The Indian Summer Monsoon (ISM) plays a crucial role in shaping the large proportion of the total precipitation over the Indian subcontinent each year. The ISM rainfall exhibits a particularly strong intraseasonal variability, that has profound socioeconomic consequences, such as agricultural planning and flood preparation. However, our understanding of the variability on this time scale is still limited due to sparse data availability in the past. In this study, we used a combination of state-of-the-art high-resolution satellite estimate of rainfall, objectively analyzed surface flux, as well as atmospheric reanalysis product to investigate the nature of the ISM intraseasonal rainfall variability and how it varies year to year. The emphasis is placed on the Bay of Bengal (BoB) where the intraseasonal ocean-atmosphere coupling is most prominent. Results show that the maximum warming of SST leads the onset of heavy precipitation event by 3-5 days, and that surface heat flux and surface wind speed are weak prior to the rain but amplifies and peaks after the rain reaches its maximum. Furthermore, the Indian Ocean Dipole (IOD) significantly affects the observed intraseasonal SST-precipitation relationship. The pre-convection SST warming is stronger and more pronounced during the negative phase of the IOD, while the signal is weaker and less organized in the positive phase. This is explained by the column-integrated moisture budget analysis which reveals that, during the ISM heavy rainfall in the BoB, there is more moisture interchange in the form of enhanced vertical advection from the ocean to atmosphere in negative IOD years as compared to positive IOD years. Knowing the distinction of ISM variabilities during opposite phases of the IOD will help contribute to a more reliable prediction of ISM activities.

  6. Convective lofting links Indian Ocean air pollution to paradoxical South Atlantic ozone maxima

    Science.gov (United States)

    Chatfield, R. B.; Guan, H.; Thompson, A. M.; Witte, J. C.

    2005-01-01

    We describe a broad resolution of the Atlantic Parado concerning the seasonal and geographic distribution, of tropical tropospheric ozone. We highlight periods of significant maximum tropospheric O3 for Jan.- April, 1999, exploiting satellite estimates and SHADOZ (Southern Hemisphere Additional Ozonesondes). Trajectory analyses connecting sondes and Total Tropospheric Ozone (TTO) maps suggest a complex influence from the Indian Ocean: beginning with mixed combustion sources, then low level transport, cumulonimbus venting, possible stratospheric input, and finally high-level transport to the west, with possible mixing over Africa. For the Jan.-March highest column-O3 periods in the Atlantic, distinct sounding peaks trace to specific NO sources, especially lightning, while in the same episodes, recurring every 20-50 days, more diffuse buildups of Indian-to-Atlantic pollution make important contributions.

  7. Indian Ocean dipole modulated wave climate of eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Anoop, T.R.; SanilKumar, V.; Shanas, P.R.; Glejin, J.; Amrutha, M.M.

    –378, 2016 www.ocean-sci.net/12/369/2016/ doi:10.5194/os-12-369-2016 © Author(s) 2016. CC Attribution 3.0 License. Indian Ocean Dipole modulated wave climate of eastern Arabian Sea T. R. Anoop1, V. Sanil Kumar1, P. R. Shanas1,2, J. Glejin1, and M. M. Amrutha1... are available on the website of the Japanese Agency of Marine–Earth Science and Technology (www.jamstec.go.jp). The tropical IO displays strong inter-annual climate vari- ability associated with the El Niño–Southern Oscillation (ENSO) and the IOD (Murtugudde et...

  8. The Indian Ocean disaster: Tsunami physics and early warning dilemmas

    Science.gov (United States)

    Lomnitz, Cinna; Nilsen-Hofseth, Sara

    Understanding the physics of tsunamis may save lives, especially near the epicenter of a large earthquake where the danger is highest and early warning is least likely to be effective.Normal modes of Earth are standing waves of the Love (toroidal) or the Rayleigh (spheroidal) variety. The Indian Ocean tsunami may have been partly or wholly caused by low-order spheroidal modes of the Earth such as 0S2, 0S3, and 0S4, that may have excited a waveguide—a layer that confines and guides a propagating wave—in the ocean.

  9. Wagging the Pacific Dog by its Indian Tail? : A west Indian Ocean Precursor to El Niño

    NARCIS (Netherlands)

    Wieners, C.E.

    2018-01-01

    Cool Sea Surface Temperature (SST) anomalies tend to prevail in the Seychelles Dome region (Southwest Indian Ocean, NE of Madagascar) during the Northern hemisphere summer-autumn 1.5 years before El Niño. This West Indian Ocean precursor might potentially help to predict El Niño/Southern Oscillation

  10. Preface to: Marine micropaleontological studies from the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Saraswat, R.

    -pollens, ostracodes, etc. The objective is to provide a comprehensive review of the developments in the oron. micropaleontological st~dies'throu~h ages, with examples from the northern Indian Ocean re,' Micropaleontological studies have experienced a sea-drift over... based foraminifera1 proxies for paleoclimatic/paleoceanographic reconstruction. The paper by Liilshy et al. provides the comprehensive details of the laboratory culture studies on benthic foraminifera carried out with the aim to refine field based...

  11. Preface to: Indian Ocean biogeochemical processes and ecological variability

    Digital Repository Service at National Institute of Oceanography (India)

    Hood, R.R.; Naqvi, S.W.A.; Wiggert, J.D.

    monsoonal in fluence. The biogeochemical and ecological impacts of this complex physical forcing are not yet fully understood. The Indian Ocean is truly one of the last great frontiers of ocea- nographic research. In addition, it appears... to be particularly vulnerable to climate change and anthropogenic impacts, yet it has been more than a decade since the last coordinated international study of biogeochemical and ecological proc esses was undertaken in this region. To obtain a better un...

  12. Dynamics of formation of ferromanganese nodules in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Ghosh, A.K.

    ., 2008). It is therefore interesting to examine and model the various factors that might influence the formation, growth and characters of nodules in the neighbouring sectors within the IONF (sector A to D, Fig. 2). The seafloor underlying... these sectors, originated from the Indian Ocean Ridge System (IORS), and is strikingly different from one sector to another. For example, the sectors A and C were formed during crustal stretching, and are characterised by a largely smooth seafloor...

  13. Net community production in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.

    . On the other hand, Sarma [2004, Net community production in the Bay of Bengal: Oxygen mass balance approach, submitted to Bio- geochemistry, 2008] computed NCP using a regional model of oxygen mass balance in the NIO. Bates et al. [2006] also estimated NCP... using an inorganic carbon mass balance model for the entire Indian Ocean. This chapter combines the results obtained from direct measurements and models and aims at improving our understanding of processes con­ trolling NCP in the NIO...

  14. Geochemical variability of MORBs along slow to intermediate spreading Carlsberg-Central Indian Ridge, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ray, D.; Misra, S.; Banerjee, R.

    ). The mixing trend definitely excludes EM1 [dehydrated and recrystallized oceanic basalt formed during subduction plus 5-10% marine pelagic sediment, Weaver, 1991], EM2 [dehydrated and recrystallized oceanic basalt formed during subduction plus 5... are plotted on or close to the mixing line between the average depleted mantle and the Indian Ocean Pelagic sediments, and this mixing line excludes the EM1, EM2 and HIMU (Fig. 12, c, e). The CR, NCIR and SCIR MORBs are closer to the average depleted...

  15. Elders recall an earlier tsunami on Indian Ocean shores

    Science.gov (United States)

    Kakar, Din Mohammad; Naeem, Ghazala; Usman, Abdullah; Hasan, Haider; Lohdi, Hira; Srinivasalu, Seshachalam; Andrade, Vanessa; Rajendran, C.P.; Naderi Beni, Abdolmajid; Hamzeh, Mohammad Ali; Hoffmann, Goesta; Al Balushi, Noora; Gale, Nora; Kodijat, Ardito; Fritz, Hermann M.; Atwater, Brian F.

    2014-01-01

    Ten years on, the Indian Ocean tsunami of 26 December 2004 still looms large in efforts to reduce coastal risk. The disaster has spurred worldwide advances in tsunami detection and warning, tsunami-risk assessment, and tsunami awareness [Satake, 2014]. Nearly a lifetime has passed since the northwestern Indian Ocean last produced a devastating tsunami. Documentation of this tsunami, in November 1945, was hindered by international instability in the wake of the Second World War and, in British India, by the approach of independence and partition. The parent earthquake, of magnitude 8.1, was widely recorded, and the tsunami registered on tide gauges, but intelligence reports and newspaper articles say little about inundation limits while permitting a broad range of catalogued death tolls. What has been established about the 1945 tsunami falls short of what's needed today for ground-truthing inundation models, estimating risk to enlarged populations, and anchoring awareness campaigns in local facts. Recent efforts to reduce coastal risk around the Arabian Sea include a project in which eyewitnesses to the 1945 tsunami were found and interviewed (Fig. 1), and related archives were gathered. Results are being made available through UNESCO's Indian Ocean Tsunami Information Center in hopes of increasing scientific understanding and public awareness of the region's tsunami hazards.

  16. Measurements within the Pacific-Indian oceans throughflow region

    Science.gov (United States)

    Fieux, M.; Andrié, C.; Delecluse, P.; Ilahude, A. G.; Kartavtseff, A.; Mantisi, F.; Molcard, R.; Swallow, J. C.

    1994-07-01

    Two hydrographic (θ, S, O 2) and trichlorofluoromethane (F-11) sections were carried out between the Australian continental shelf and Indonesia, in August 1989, on board the R.V. Marion Dufresne. The sections lie in the easternmost part of the Indian Ocean where the throughflow between the Pacific Ocean and the Indian Ocean emerges. They allow us to describe the features of the water-property and circulation fields of the throughflow at its entrance in the Indian Ocean. Between the Australian continental shelf and Bali, the Subtropical and Central waters are separated from the waters of the Indonesian seas by a sharp hydrological front, located around 13°30 S, below the thermocline down to 700 m. Near the coast of Bali, upwelling occurs in the near-surface layer under the effect of the southeast monsoon; at depth, between 300 m to more than 800 m, a water mass of northern Indian Ocean origin was present. From the characteristics of the bottom water found in the Lombok basin, the maximum depth of the Java ridge which separates the Lombok basin from the Northwest Australian basin lies around 3650 m. Off Sumba, Savu, Roti and Timor channels a core of low salinity and high oxygen content near-surface water was found in the axis of each channel, which suggests strong currents from the interior Indonesian seas towards the Indian Ocean. The entrance of the deep water flowing in the opposite direction, from the Indian Ocean to the Timor basin, was marked below 1400 m to the sill depth, through an increase of salinity and oxygen content. The flow reversal, observed briefly by a Pegasus direct current profiler in the Timor strait, was located at 1200 m depth. During the southeast monsoon, the net (geostrophic + Ekman) transport calculated on the section Australia-Bali give an estimate of the throughflow between 0 and 500 m of 22 ± 4 × 10 6 m 3 s -1 towards the Indian Ocean, with a concentration of the transport in the upper layers (19 × 10 6 m 3 s -1 in 0-200 m) and

  17. Distribution, ecology and polymorphic behaviour of the genus Oxycephalus (Hyperiidea, Oxycephalidae) in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, K.K.C.

    There have been many controversies on the number of valid, species under Oxycephalus including the studies made from Indian waters. This is the first comprehensive account on the distribution of this genus covering the entire Indian Ocean through...

  18. Petrology of seamounts in the Central Indian Ocean Basin: Evidence for near-axis origin

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Batiza, R.; Iyer, S.D.

    Previous studies on the distribution and morphology of ancient seamount chains (>50 Ma) in the Central Indian Ocean basin (CIOB) indicated their generation from the fast spreading Southeast Indian Ridge. The petrology of some of these seamounts...

  19. Slow spreading ridges of the Indian Ocean: An overview of marine geophysical investigations

    Digital Repository Service at National Institute of Oceanography (India)

    KameshRaju, K.A.; Mudholkar, A.V.; Samudrala, K.

    Sparse and non-availability of high resolution geophysical data hindered the delineation of accurate morphology, structural configuration, tectonism and spreading history of Carlsberg Ridge (CR) and Central Indian Ridges (CIR) in the Indian Ocean...

  20. Satellite Ocean Color Sensor Design Concepts and Performance Requirements

    Science.gov (United States)

    McClain, Charles R.; Meister, Gerhard; Monosmith, Bryan

    2014-01-01

    In late 1978, the National Aeronautics and Space Administration (NASA) launched the Nimbus-7 satellite with the Coastal Zone Color Scanner (CZCS) and several other sensors, all of which provided major advances in Earth remote sensing. The inspiration for the CZCS is usually attributed to an article in Science by Clarke et al. who demonstrated that large changes in open ocean spectral reflectance are correlated to chlorophyll-a concentrations. Chlorophyll-a is the primary photosynthetic pigment in green plants (marine and terrestrial) and is used in estimating primary production, i.e., the amount of carbon fixed into organic matter during photosynthesis. Thus, accurate estimates of global and regional primary production are key to studies of the earth's carbon cycle. Because the investigators used an airborne radiometer, they were able to demonstrate the increased radiance contribution of the atmosphere with altitude that would be a major issue for spaceborne measurements. Since 1978, there has been much progress in satellite ocean color remote sensing such that the technique is well established and is used for climate change science and routine operational environmental monitoring. Also, the science objectives and accompanying methodologies have expanded and evolved through a succession of global missions, e.g., the Ocean Color and Temperature Sensor (OCTS), the Seaviewing Wide Field-of-view Sensor (SeaWiFS), the Moderate Resolution Imaging Spectroradiometer (MODIS), the Medium Resolution Imaging Spectrometer (MERIS), and the Global Imager (GLI). With each advance in science objectives, new and more stringent requirements for sensor capabilities (e.g., spectral coverage) and performance (e.g., signal-to-noise ratio, SNR) are established. The CZCS had four bands for chlorophyll and aerosol corrections. The Ocean Color Imager (OCI) recommended for the NASA Pre-Aerosol, Cloud, and Ocean Ecosystems (PACE) mission includes 5 nanometers hyperspectral coverage from 350 to

  1. Anticipated prospects and civilian applications of Indian satellite navigation services in Sri Lanka

    Directory of Open Access Journals (Sweden)

    I.P. Senanayake

    2013-06-01

    In this paper, positive impacts of 3 Indian Navigational Satellite programmes (GAGAN, IRNSS and INSAT-MSS reporting system for the civilian applications over Sri Lanka are discussed. Other neighbouring countries covered under the footprint of Indian navigational satellite programmes can also employ these services for the location based applications productively.

  2. Warming of the Indian Ocean Threatens Eastern and Southern Africa, but could be Mitigated by Agricultural Development

    Science.gov (United States)

    Funk, Chris; Dettinger, Michael D.; Brown, Molly E.; Michaelsen, Joel C.; Verdin, James P.; Barlow, Mathew; Howell, Andrew

    2008-01-01

    Since 1980, the number of undernourished people in eastern and southern Africa has more than doubled. Rural development stalled and rural poverty expanded during the 1990s. Population growth remains very high and declining per capita agricultural capacity retards progress towards Millennium Development goals. Analyses of in situ station data and satellite observations of precipitation identify another problematic trend. Main growing season rainfall receipts have diminished by approximately 15% in food insecure countries clustered along the western rim of the Indian Ocean. Occurring during the main growing seasons in poor countries dependent on rain fed agriculture, these declines are societally dangerous. Will they persist or intensify? Tracing moisture deficits upstream to an anthropogenically warming Indian Ocean leads us to conclude that further rainfall declines are likely. We present analyses suggesting that warming in the central Indian Ocean disrupts onshore moisture transports, reducing continental rainfall. Thus late 20th century anthropogenic Indian Ocean warming has probably already produced societally dangerous climate change by creating drought and social disruption in some of the world's most fragile food economies. We quantify the potential impacts of the observed precipitation and agricultural capacity trends by modeling millions of undernourished people as a function of rainfall, population, cultivated area, seed and fertilizer use. Persistence of current tendencies may result in a 50% increase in undernourished people. On the other hand, modest increases in per capita agricultural productivity could more than offset the observed precipitation declines. Investing in agricultural development can help mitigate climate change while decreasing rural poverty and vulnerability.

  3. Equatorial Indian Ocean subsurface current variability in an Ocean General Circulation Model

    Science.gov (United States)

    Gnanaseelan, C.; Deshpande, Aditi

    2018-03-01

    The variability of subsurface currents in the equatorial Indian Ocean is studied using high resolution Ocean General Circulation Model (OGCM) simulations during 1958-2009. February-March eastward equatorial subsurface current (ESC) shows weak variability whereas strong variability is observed in northern summer and fall ESC. An eastward subsurface current with maximum amplitude in the pycnocline is prominent right from summer to winter during strong Indian Ocean Dipole (IOD) years when air-sea coupling is significant. On the other hand during weak IOD years, both the air-sea coupling and the ESC are weak. This strongly suggests the role of ESC on the strength of IOD. The extension of the ESC to the summer months during the strong IOD years strengthens the oceanic response and supports intensification and maintenance of IODs through modulation of air sea coupling. Although the ESC is triggered by equatorial winds, the coupled air-sea interaction associated with IODs strengthens the ESC to persist for several seasons thereby establishing a positive feedback cycle with the surface. This suggests that the ESC plays a significant role in the coupled processes associated with the evolution and intensification of IOD events by cooling the eastern basin and strengthening thermocline-SST (sea surface temperature) interaction. As the impact of IOD events on Indian summer monsoon is significant only during strong IOD years, understanding and monitoring the evolution of ESC during these years is important for summer monsoon forecasting purposes. There is a westward phase propagation of anomalous subsurface currents which persists for a year during strong IOD years, whereas such persistence or phase propagation is not seen during weak IOD years, supporting the close association between ESC and strength of air sea coupling during strong IOD years. In this study we report the processes which strengthen the IOD events and the air sea coupling associated with IOD. It also unravels

  4. Retrospective satellite ocean color analysis of purposeful and natural ocean iron fertilization

    Science.gov (United States)

    Westberry, Toby K.; Behrenfeld, Michael J.; Milligan, Allen J.; Doney, Scott C.

    2013-03-01

    Significant effort has been invested in understanding the role of iron in marine ecosystems over the past few decades. What began as shipboard amendment experiments quickly grew into a succession of in situ, mesoscale ocean iron fertilization (OIF) experiments carried out in all three high nutrient low chlorophyll (HNLC) regions of the world ocean. Dedicated process studies have also looked at regions of the ocean that are seasonally exposed to iron-replete conditions as natural OIF experiments. However, one problem common to many OIF experiments is determination of biological response beyond the duration of the experiment (typicallyfloristic shifts in the phytoplankton community. Further, a consistent pattern of decreased satellite fluorescence efficiency (FLH:Chl or ϕf) following OIF is observed that is in agreement with current understanding of phytoplankton physiological responses to relief from iron stress. The current study extends our ability to retrieve phytoplankton physiology from space-based sensors, strengthens the link between satellite fluorescence and iron availability, and shows that satellite ocean color analyses provide a unique tool for monitoring OIF experiments.

  5. Bacterial Diversity in Deep-Sea Sediments from Afanasy Nikitin Seamount, Equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Khandeparker, R.; Meena, R.M.; Deobagkar, D.D.

    Deep-sea sediments can reveal much about the last 200 million years of Earth history, including the history of ocean life and climate. Microbial diversity in Afanasy Nikitin seamount located at Equatorial East Indian Ocean (EEIO) was investigated...

  6. Oceanographic cruise Indian Ocean and Java Trench June 1969 (NODC Accession 7100908)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This report contains oceanographic data which was obtained aboard H.M.A.S DIAMANTINA during an oceanographic cruise in the Java Trench and the Indian Ocean during...

  7. TOGA Sea Level Center: Data from the Indian Ocean (NODC Accession 9000251)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains a scan of the analog publication 'TOGA Sea Level Center: Data from the Indian Ocean'. Abstract from p. iii of the publication: The TOGA Sea...

  8. Third Indian National Conference on Harbour and Ocean Engineering (INCHOE - 2004). Proceedings

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; SanilKumar, V.; Jayakumar, S.

    The two volumes contain 103 scientific papers in the field of harbour and ocean engineering, presented at the Third Indian National Conference on Harbour and Ocean Engineering (INCHOE - 2004), held at National Institute of Oceanography (NIO), Dona...

  9. Carbonate preservation during the 'mystery interval' in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.S.; Naidu, P.D.

    maximum is a feature noted across the world oceans and considered to signify carbonate preservation, although it is missing from many sediment cores from the eastern equatorial Pacific, tropical Atlantic and subtropical Indian Ocean The carbonate...

  10. Simulated seasonal and interannual variability of mixed layer heat budget in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    DeBoyer Montegut, C.; Vialard, J.; Shenoi, S.S.C.; Shankar, D.; Durand, F.; Ethe, C.; Madec, G.

    A global Ocean General Circulation Model (OGCM) is used to investigate the mixed layer heat budget of the Northern Indian Ocean (NIO). The model is validated against observations and shows a fairly good agreement with mixed layer depth data...

  11. Internal constitution of manganese nodules from the Central Indian Ocean basin

    Digital Repository Service at National Institute of Oceanography (India)

    Ghosh, A.K.; Mukhopadhyay, R.

    Morphological, chemical, physical and acoustic properties of Mn-nodules in the the Indian Ocean are inter-linked and depend much on local and regional oceanic environments. These nodules are anisotropic and sound propagation is faster parallel...

  12. General circulation and tracers: studies in the Western Indian Ocean

    International Nuclear Information System (INIS)

    Jamous, Daniel

    1991-01-01

    The main question addressed in this thesis is how to best use the information obtained from hydro-biogeochemical tracer data, to study the oceanic general circulation in the Western Indian Ocean. First, a principal component analysis is performed on a historical data set. The tracers considered are temperature, salinity, density, oxygen, phosphate and silica. The method reduces the amount of data to be considered by a factor of 5. It reproduces correctly and efficiently the large-scale distributions of these oceanic properties. The analysed data are then used in a finite-difference nonlinear inverse model. The grid has a resolution of 4 deg. by 4 deg.. Dynamical as well as tracer conservation constraints are used. These constraints are well satisfied by the obtained solutions but the associated errors remain large. Additional constraints would be required in order to discuss the different solutions in more detail. Finally, a qualitative study is done on the deep distribution of helium-3. The data show several important features linked to hydrothermal input in the Gulf of Aden and on the Central Indian Ridge, and to the origin of water masses and deep circulation characteristics. However additional data are required in order to clarify the distribution of this tracer in other key areas. (author) [fr

  13. Southern Indian Ocean SST as a modulator for the progression of Indian summer monsoon

    Science.gov (United States)

    Shahi, Namendra Kumar; Rai, Shailendra; Mishra, Nishant

    2018-01-01

    This study explores the possibility of southern Indian Ocean (SIO) sea surface temperature (SST) as a modulator for the early phase of Indian summer monsoon and its possible physical mechanism. A dipole-like structure is obtained from the empirical orthogonal function (EOF) analysis which is similar to an Indian Ocean subtropical dipole (IOSD) found earlier. A subtropical dipole index (SDI) is defined based on the SST anomaly over the positive and negative poles. The regression map of rainfall over India in the month of June corresponding to the SDI during 1983-2013 shows negative patterns along the Western Ghats and Central India. However, the regression pattern is insignificant during 1952-1982. The multiple linear regression models and partial correlation analysis also indicate that the SDI acts as a dominant factor to influence the rainfall over India in the month of June during 1983-2013. The similar result is also obtained with the help of composite rainfall over the land points of India in the month of June for positive (negative) SDI events. It is also observed that the positive (negative) SDI delays (early) the onset dates of Indian monsoon over Kerala during the time domain of our study. The study is further extended to identify the physical mechanism of this impact, and it is found that the heating (cooling) in the region covering SDI changes the circulation pattern in the SIO and hence impacts the progression of monsoon in India.

  14. Pelagic ecology of the South West Indian Ocean Ridge seamounts: Introduction and overview

    Science.gov (United States)

    Rogers, A. D.

    2017-02-01

    The Indian Ocean was described by Behrman (1981) as the "Forlorn Ocean", a region neglected by science up to the late-1950s. For example, the Challenger Expedition from 1872 to 1876 largely avoided the Indian Ocean, sailing from Cape Town into Antarctic waters sampling around the Prince Edward Islands, Kerguelen Island and Crozet Islands before heading to Melbourne. From 1876 to the 1950s there were expeditions on several vessels including the Valdivia, Gauss and Planet (Germany), the Snellius (Netherlands), Discovery II, MahaBiss (United Kingdom), Albatross (Sweden), Dana and Galathea (Denmark; Behrman, 1981). There was no coordination between these efforts and overall the Indian Ocean, especially the deep sea remained perhaps the most poorly explored of the world's oceans. This situation was largely behind the multilateral effort represented by the International Indian Ocean Expedition (IIEO), which was coordinated by the Scientific Committee for Ocean Research (SCOR), and which ran from 1959-1965. Work during this expedition focused on the Arabian Sea, the area to the northwest of Australia and the waters over the continental shelves and slopes of coastal states in the region. Subsequently several large-scale international oceanographic programmes have included significant components in the Indian Ocean, including the Joint Global Ocean Flux Study (JGOFS) and the World Ocean Circulation Experiment (WOCE). These studies were focused on physical oceanographic measurements and biogeochemistry and whilst the Indian Ocean is still less understood than other large oceans it is now integrated into the major ocean observation systems (Talley et al., 2011). This cannot be said for many aspects of the biology of the region, despite the fact that the Indian Ocean is one of the places where exploitation of marine living resources is still growing (FAO, 2016). The biology of the deep Indian Ocean outside of the Arabian Sea is particularly poorly understood given the presence

  15. Detecting the influence of ocean process on the moisture supply for India summer monsoon from Satellite Sea Surface Salinity

    Science.gov (United States)

    Tang, W.; Yueh, S. H.; Liu, W. T.; Fore, A.; Hayashi, A.

    2016-02-01

    A strong contrast in the onset of Indian summer monsoon was observed by independent satellites: average rain rate over India subcontinent (IS) in June was more than doubled in 2013 than 2012 (TRMM); also observed are larger area of wet soil (Aquarius) and high water storage (GRACE). The difference in IS rainfall was contributed to the moisture inputs through west coast of India, estimated from ocean wind (OSCAT2) and water vapor (TMI). This is an interesting testbed for studying the role of ocean on terrestrial water cycle, in particular the Indian monsoon, which has tremendous social-economical impact. What is the source of extra moisture in 2013 or deficit in 2012 for the monsoon onset? Is it possible to quantify the contribution of ocean process that maybe responsible for redistributing the freshwater in favor of the summer monsoon moisture supply? This study aims to identify the influence of ocean processes on the freshwater exchange between air-sea interfaces, using Aquarius sea surface salinity (SSS). We found two areas in Indian Ocean with high correlation between IS rain rate and Aquarius SSS: one area is in the Arabian Sea adjacent to IS, another area is a horizontal patch from 60°E to 100°E centered around 10°S. On the other hand, E-P (OAflux, TRMM) shows no similar correlation patterns with IS rain. Based on the governing equation of the salt budget in the upper ocean, we define the freshwater flux, F, from the oceanic branch of the water cycle, including contributions from salinity tendency, advection, and subsurface process. The tendency and advection terms are estimated using Aquarius SSS and OSCAR ocean current. We will present results of analyzing the spatial and temporal variability of F and evidence of and hypothesis on how the oceanic processes may enhance the moisture supply for summer Indian monsoon onset in 2013 comparing with 2012. The NASA Soil Moisture Active Passive (SMAP) has been producing the global soil moisture (SM) every 2-3 days

  16. A lightning climatology of the South-West Indian Ocean

    Directory of Open Access Journals (Sweden)

    C. Bovalo

    2012-08-01

    Full Text Available The World Wide Lightning Location Network (WWLLN data have been used to perform a lightning climatology in the South-West Indian Ocean (SWIO region from 2005 to 2011. Maxima of lightning activity were found in the Maritime Continent and southwest of Sri Lanka (>50 fl km−2 yr−1 but also over Madagascar and above the Great Lakes of East Africa (>10–20 fl km−2 yr−1. Lightning flashes within tropical storms and tropical cyclones represent 50 % to 100 % of the total lightning activity in some oceanic areas of the SWIO (between 10° S and 20° S.

    The SWIO is characterized by a wet season (November to April and a dry season (May to October. As one could expect, lightning activity is more intense during the wet season as the Inter Tropical Convergence Zone (ITCZ is present over all the basin. Flash density is higher over land in November–December–January with values reaching 3–4 fl km−2 yr−1 over Madagascar. During the dry season, lightning activity is quite rare between 10° S and 25° S. The Mascarene anticyclone has more influence on the SWIO resulting in shallower convection. Lightning activity is concentrated over ocean, east of South Africa and Madagascar.

    A statistical analysis has shown that El Niño–Southern Oscillation mainly modulates the lightning activity up to 56.8% in the SWIO. The Indian Ocean Dipole has a significant contribution since ~49% of the variability is explained by this forcing in some regions. The Madden–Julian Oscillation did not show significative impact on the lightning activity in our study.

  17. [Post nearly Drowning Vibrio alginolyticus Septicemia Acquired in Reunion (Indian Ocean)].

    Science.gov (United States)

    Gaüzère, B-A; Chanareille, P; Vandroux, D

    2016-08-01

    AbstractWe report the first case of Vibrio alginolyticus septicemia in the Indian Ocean (Reunion Island), in a patient (70-year-old-man) with multiple underlying conditions, following a nearly drowning in the lagoon of Reunion. From now on, V. alginolyticus should be considered as a possible agent of septicemia in the Indian Ocean, particularly following marine activities.

  18. Distribution of Oxycephalidae (Hyperiidea-Amphipoda) in the Indian Ocean- A statistical study

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, K.K.C.; Jayalakshmy, K.V.

    Statistical analysis of oxycephalids on coexistence of the species showed two clusters of high affinity in the Arabian Sea, four in the Bay of Bengal, one in the South East Indian Ocean and three in the South West Indian Ocean. Species occurring...

  19. The Indian Ocean Experiment : Widespread air pollution from South and Southeast Asia

    NARCIS (Netherlands)

    Lelieveld, J; Crutzen, PJ; Ramanathan, A.; Andreae, MO; Brenninkmeijer, CAM; Campos, T; Cass, GR; Dickerson, RR; Fischer, H; de Gouw, JA; Hansel, A; Jefferson, A; Kley, D; de Laat, ATJ; Lal, S; Lawrence, MG; Lobert, JM; Mayol-Bracero, OL; Mitra, AP; Novakov, T; Oltmans, SJ; Prather, KA; Reiner, T; Rodhe, H; Scheeren, HA; Sikka, D; Williams, J

    2001-01-01

    The Indian Ocean Experiment (INDOEX) was an international, multiplatform field campaign to measure Long-range transport of air pollution from South and Southeast Asia toward the Indian Ocean during the dry monsoon season in January to March 1999. Surprisingly high pollution Levels were observed over

  20. Dynamics of large scale 3-dimensional circulation of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Swapna, P.

    -diagnostic and prognostic modes. Such a model could identify both the local and remote forcing of the Indian Ocean circulation. The other objectives of the thesis are the following: (i) To study the steady state 3-dimensional circulation of Indian Ocean based on semi...

  1. Larval and postlarval stages of Atypopenaeus Alcock (Decapoda, Penaeidae: Penaeinae) from Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Paulinose, V.T.

    Two of the early mysis stages and an early postlarva of a species of Atypopenaeus are described here for the first time. A total of 15 specimens were obtained from the Indian Ocean during the International Indian Ocean Expedition (IIOE). The species...

  2. Mechanisms of Mixed-Layer Salinity Seasonal Variability in the Indian Ocean

    Science.gov (United States)

    Köhler, Julia; Serra, Nuno; Bryan, Frank O.; Johnson, Benjamin K.; Stammer, Detlef

    2018-01-01

    Based on a joint analysis of an ensemble mean of satellite sea surface salinity retrievals and the output of a high-resolution numerical ocean circulation simulation, physical processes are identified that control seasonal variations of mixed-layer salinity (MLS) in the Indian Ocean, a basin where salinity changes dominate changes in density. In the northern and near-equatorial Indian Ocean, annual salinity changes are mainly driven by respective changes of the horizontal advection. South of the equatorial region, between 45°E and 90°E, where evaporation minus precipitation has a strong seasonal cycle, surface freshwater fluxes control the seasonal MLS changes. The influence of entrainment on the salinity variance is enhanced in mid-ocean upwelling regions but remains small. The model and observational results reveal that vertical diffusion plays a major role in precipitation and river runoff dominated regions balancing the surface freshwater flux. Vertical diffusion is important as well in regions where the advection of low salinity leads to strong gradients across the mixed-layer base. There, vertical diffusion explains a large percentage of annual MLS variance. The simulation further reveals that (1) high-frequency small-scale eddy processes primarily determine the salinity tendency in coastal regions (in particular in the Bay of Bengal) and (2) shear horizontal advection, brought about by changes in the vertical structure of the mixed layer, acts against mean horizontal advection in the equatorial salinity frontal regions. Observing those latter features with the existing observational components remains a future challenge.

  3. Zooplankton biomass and abundance of Antarctic krill Euphausia superba DANA in Indian Ocean sector of the southern ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Parulekar, A.H.

    Zooplankton sampling was carried out during the first six Indian Scientific Expeditions to Antarctica (1981-1987) to estimate krill abundance in the Indian sector of the Southern Ocean (between 35 to 70 degrees S and 10 to 52 degrees E). This study...

  4. Depths of Intraplate Indian Ocean Earthquakes from Waveform Modeling

    Science.gov (United States)

    Baca, A. J.; Polet, J.

    2014-12-01

    The Indian Ocean is a region of complex tectonics and anomalous seismicity. The ocean floor in this region exhibits many bathymetric features, most notably the multiple inactive fracture zones within the Wharton Basin and the Ninetyeast Ridge. The 11 April 2012 MW 8.7 and 8.2 strike-slip events that took place in this area are unique because their rupture appears to have extended to a depth where brittle failure, and thus seismic activity, was considered to be impossible. We analyze multiple intraplate earthquakes that have occurred throughout the Indian Ocean to better constrain their focal depths in order to enhance our understanding of how deep intraplate events are occurring and more importantly determine if the ruptures are originating within a ductile regime. Selected events are located within the Indian Ocean away from major plate boundaries. A majority are within the deforming Indo-Australian tectonic plate. Events primarily display thrust mechanisms with some strike-slip or a combination of the two. All events are between MW5.5-6.5. Event selections were handled this way in order to facilitate the analysis of teleseismic waveforms using a point source approximation. From these criteria we gathered a suite of 15 intraplate events. Synthetic seismograms of direct P-waves and depth phases are computed using a 1-D propagator matrix approach and compared with global teleseismic waveform data to determine a best depth for each event. To generate our synthetic seismograms we utilized the CRUST1.0 software, a global crustal model that generates velocity values at the hypocenter of our events. Our waveform analysis results reveal that our depths diverge from the Global Centroid Moment Tensor (GCMT) depths, which underestimate our deep lithosphere events and overestimate our shallow depths by as much as 17 km. We determined a depth of 45km for our deepest event. We will show a comparison of our final earthquake depths with the lithospheric thickness based on

  5. Temperature Data From AUSTRALIA STAR and Other Platforms From Indian Ocean and South Pacific Ocean From 19860929 to 19890106 (NODC Accession 8900196)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature data from Australia Star and other ships from Indian Ocean and South Pacific Ocean from September 29, 1986 to January 6, 1989. The data were collected by...

  6. The 50th Anniversary of the International Indian Ocean Expedition: An Update on Current Planning Efforts and Progress

    Science.gov (United States)

    Hood, Raleigh; D'Adamo, Nick; Burkill, Peter; Urban, Ed; Bhikajee, Mitrasen

    2014-05-01

    The International Indian Ocean Expedition (IIOE) was one of the greatest international, interdisciplinary oceanographic research efforts of all time. Planning for the IIOE began in 1959 and the project officially continued through 1965, with forty-six research vessels participating under fourteen different flags. The IIOE motivated an unprecedented number of hydrographic surveys (and repeat surveys) over the course of the expedition covering the entire Indian Ocean basin. And it was an interdisciplinary endeavor that embraced physical oceanography, chemical oceanography, meteorology, marine biology, marine geology and geophysics. The end of 2015 will mark the 50th Anniversary of the completion of the IIOE. In the 50 years since the IIOE three fundamental changes have taken place in ocean science. The first is the deployment of a broad suite of oceanographic sensors on satellites that have dramatically improved the characterization of both physical and biological oceanographic variability. The second is the emergence of new components of the ocean observing system, most notably remote sensing and Argo floats. And the third is the development of ocean modeling in all its facets from short-term forecasting to seasonal prediction to climate projections. These advances have revolutionized our understanding of the global oceans, including the Indian Ocean. Compared to the IIOE era, we now have the capacity to provide a much more integrated picture of the Indian Ocean, especially if these new technologies can be combined with targeted and well-coordinated in situ measurements. In this presentation we report on current efforts to motivate an IIOE 50th Anniversary Celebration (IIOE-2). We envision this IIOE-2 as a 5-year expedition and effort beginning in 2015 and continuing through to 2020. An important objective of our planning efforts is assessing ongoing and planned research activities in the Indian Ocean in the 2015 to 2020 time frame, with the goal of embracing and

  7. Recent predictors of Indian summer monsoon based on Indian and Pacific Ocean SST

    Science.gov (United States)

    Shahi, Namendra Kumar; Rai, Shailendra; Mishra, Nishant

    2018-02-01

    This study investigates the relationship between sea surface temperature (SST) of various geographical locations of Indian and Pacific Ocean with the Indian summer monsoon rainfall (ISMR) to identify possible predictors of ISMR. We identified eight SST predictors based on spatial patterns of correlation coefficients between ISMR and SST of the regions mentioned above during the time domain 1982-2013. The five multiple linear regression (MLR) models have been developed by these predictors in various combinations. The stability and performance of these MLR models are verified using cross-validation method and other statistical methods. The skill of forecast to predict observed ISMR from these MLR models is found to be substantially better based on various statistical verification measures. It is observed that the MLR models constructed using the combination of SST indices in tropical and extra tropical Indian and Pacific is able to predict ISMR accurately for almost all the years during the time domain of our study. We tried to propose the physical mechanism of the teleconnection through regression analysis with wind over Indian subcontinent and the eight predictors and the results are in the conformity with correlation coefficient analysis. The robustness of these models is seen by predicting the ISMR during recent independent years of 2014-2017 and found the model 5 is able to predict ISMR accurately in these years also.

  8. SWOT, The Surface Water and Ocean Topography Satellite Mission (Invited)

    Science.gov (United States)

    Alsdorf, D.; Andreadis, K.; Bates, P. D.; Biancamaria, S.; Clark, E.; Durand, M. T.; Fu, L.; Lee, H.; Lettenmaier, D. P.; Mognard, N. M.; Moller, D.; Morrow, R. A.; Rodriguez, E.; Shum, C.

    2009-12-01

    Surface fresh water is essential for life, yet we have surprisingly poor knowledge of its variability in space and time. Similarly, ocean circulation fundamentally drives global climate variability, yet the ocean current and eddy field that affects ocean circulation and heat transport at the sub-mesoscale resolution and particularly near coastal and estuary regions, is poorly known. About 50% of the vertical exchange of water properties (nutrients, dissovled CO2, heat, etc) in the upper ocean is taking place at the sub-mesoscale. Measurements from the Surface Water and Ocean Topography satellite mission (SWOT) will make strides in understanding these processes and improving global ocean models for studying climate change. SWOT is a swath-based interferometric-altimeter designed to acquire elevations of ocean and terrestrial water surfaces at unprecedented spatial and temporal resolutions. The mission will provide measurements of storage changes in lakes, reservoirs, and wetlands as well as estimates of discharge in rivers. These measurements are important for global water and energy budgets, constraining hydrodynamic models of floods, carbon evasion through wetlands, and water management, especially in developing nations. Perhaps most importantly, SWOT measurements will provide a fundamental understanding of the spatial and temporal variations in global surface waters, which for many countries are the primary source of water. An on-going effort, the “virtual mission” (VM) is designed to help constrain the required height and slope accuracies, the spatial sampling (both pixels and orbital coverage), and the trade-offs in various temporal revisits. Example results include the following: (1) Ensemble Kalman filtering of VM simulations recover water depth and discharge, reducing the discharge RMSE from 23.2% to 10.0% over an 84-day simulation period, relative to a simulation without assimilation. (2) Ensemble-based data assimilation of SWOT like measurements yields

  9. Monsoon-driven variability in the southern Red Sea and the exchange with the Indian Ocean

    Science.gov (United States)

    Sofianos, S. S.; Papadopoulos, V. P.; Abualnaja, Y.; Nenes, A.; Hoteit, I.

    2016-02-01

    Although progress has been achieved in describing and understanding the mean state and seasonal cycle of the Red Sea dynamics, their interannual variability is not yet well evaluated and explained. The thermohaline characteristics and the circulation patterns present strong variability at various time scales and are affected by the strong and variable atmospheric forcing and the exchange with the Indian Ocean and the gulfs located at the northern end of the basin. Sea surface temperature time-series, derived from satellite observations, show considerable trends and interannual variations. The spatial variability pattern is very diverse, especially in the north-south direction. The southern part of the Red Sea is significantly influenced by the Indian Monsoon variability that affects the sea surface temperature through the surface fluxes and the circulation patterns. This variability has also a strong impact on the lateral fluxes and the exchange with the Indian Ocean through the strait of Bab el Mandeb. During summer, there is a reversal of the surface flow and an intermediate intrusion of a relatively cold and fresh water mass. This water originates from the Gulf of Aden (the Gulf of Aden Intermediate Water - GAIW), is identified in the southern part of the basin and spreads northward along the eastern Red Sea boundary to approximately 24°N and carried across the Red Sea by basin-size eddies. The GAIW intrusion plays an important role in the heat and freshwater budget of the southern Red Sea, especially in summer, impacting the thermohaline characteristics of the region. It is a permanent feature of the summer exchange flow but it exhibits significant variation from year to year. The intrusion is controlled by a monsoon-driven pressure gradient in the two ends of the strait and thus monsoon interannual variability can laterally impose its signal to the southern Red Sea thermohaline patterns.

  10. Assimilation of satellite altimeter data into an open ocean model

    Science.gov (United States)

    Vogeler, Armin; SchröTer, Jens

    1995-08-01

    Geosat sea surface height data are assimilated into an eddy-resolving quasi-geostrophic open ocean model using the adjoint technique. The method adjusts the initial conditions for all layers and is successful on the timescale of a few weeks. Time-varying values for the open boundaries are prescribed by a much larger quasi-geostrophic model of the Antarctic Circumpolar Current (ACC). Both models have the same resolution of approximately 20×20 km (1/3°×1/6°), have three layers, and include realistic bottom topography and coastlines. The open model box is embedded in the African sector of the ACC. For continuous assimilation of satellite data into the larger model the nudging technique is applied. These results are used for the adjoint optimization procedure as boundary conditions and as a first guess for the initial condition. For the open model box the difference between model and satellite sea surface height that remains after the nudging experiment amounts to a 19-cm root-mean-square error (rmse). By assimilation into the regional model this value can be reduced to a 6-cm rmse for an assimilation period of 20 days. Several experiments which attempt to improve the convergence of the iterative optimization method are reported. Scaling and regularization by smoothing have to be applied carefully. Especially during the first 10 iterations, the convergence can be improved considerably by low-pass filtering of the cost function gradient. The result of a perturbation experiment shows that for longer assimilation periods the influence of the boundary values becomes dominant and they should be determined inversely by data assimilation into the open ocean model.

  11. The ocean-atmosphere response to wind-induced thermocline changes in the tropical South Western Indian Ocean

    NARCIS (Netherlands)

    Manola, Iris; Selten, F. M.; De Ruijter, W. P M; Hazeleger, W.

    2014-01-01

    In the Indian Ocean basin the sea surface temperatures (SSTs) are most sensitive to changes in the oceanic depth of the thermocline in the region of the Seychelles Dome. Observational studies have suggested that the strong SST variations in this region influence the atmospheric evolution around the

  12. An initial assessment of Ocean Energy Resources in the Western Indian Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Hammar, Linus; Ehnberg, Jimmy

    2011-07-01

    The demand for modern energy is accelerating in the Western Indian Ocean (coastal East Africa). A mixture of different energy sources will by necessity be the option for the long-term future and the most adequate solutions naturally vary between locations. The vast coastlines and many islands of the region make ocean energy (OE) a relevant field to explore. With an early understanding of the resources strategic planning towards sustainable development is facilitate. Moreover, early awareness facilitates a respectful integration of new technologies in the fragile and for local people invaluable ecosystems. This study provides a first assessment of the frontier OE technologies and corresponding resources in the region. Five renewable Ocean Energy technologies have been reviewed and the physical resource abundance for respective energy source has been screened based on available literature and databases. The Western Indian Ocean is shared between nine African countries and two French departments. The studied countries are the Comoros, Kenya, Madagascar, Mauritius, Mayotte, Mozambique, the Seychelles, Tanzania, and Reunion. The energy situation is insufficient throughout the region, either as consequence of lacking domestic energy sources or rudimentary grid extension. The results indicate that ocean energy resources are abundant in much of the region, but different sources have potential in different areas. Several countries have favourable physical conditions for extracting energy from waves and from the temperature gradient between the surface and deep water. Wave power is a young but currently available technology which can be utilized for both large- and small-scale applications. Ocean Thermal Energy Conversion is a technology under development that, once proven, may be applicable for large-scale power production. The physical conditions for small-scale tidal barrage power, tidal stream power, and ocean current power are less pronounced but may be of interest at

  13. Analysis of Tropical Cyclone Tracks in the North Indian Ocean

    Science.gov (United States)

    Patwardhan, A.; Paliwal, M.; Mohapatra, M.

    2011-12-01

    Cyclones are regarded as one of the most dangerous meteorological phenomena of the tropical region. The probability of landfall of a tropical cyclone depends on its movement (trajectory). Analysis of trajectories of tropical cyclones could be useful for identifying potentially predictable characteristics. There is long history of analysis of tropical cyclones tracks. A common approach is using different clustering techniques to group the cyclone tracks on the basis of certain characteristics. Various clustering method have been used to study the tropical cyclones in different ocean basins like western North Pacific ocean (Elsner and Liu, 2003; Camargo et al., 2007), North Atlantic Ocean (Elsner, 2003; Gaffney et al. 2007; Nakamura et al., 2009). In this study, tropical cyclone tracks in the North Indian Ocean basin, for the period 1961-2010 have been analyzed and grouped into clusters based on their spatial characteristics. A tropical cyclone trajectory is approximated as an open curve and described by its first two moments. The resulting clusters have different centroid locations and also differently shaped variance ellipses. These track characteristics are then used in the standard clustering algorithms which allow the whole track shape, length, and location to be incorporated into the clustering methodology. The resulting clusters have different genesis locations and trajectory shapes. We have also examined characteristics such as life span, maximum sustained wind speed, landfall, seasonality, many of which are significantly different across the identified clusters. The clustering approach groups cyclones with higher maximum wind speed and longest life span in to one cluster. Another cluster includes short duration cyclonic events that are mostly deep depressions and significant for rainfall over Eastern and Central India. The clustering approach is likely to prove useful for analysis of events of significance with regard to impacts.

  14. The Indian Ocean tsunami and private donations to NGOs.

    Science.gov (United States)

    Kim, Youngwan; Nunnenkamp, Peter; Bagchi, Chandreyee

    2016-10-01

    Non-governmental organisations (NGOs) are widely believed to raise their flag in humanitarian hotspots with a strong media presence in order to attract higher private donations. We assess this hypothesis by comparing the changes in donations between US-based NGOs with and without aid operations in the four countries most affected by the tsunami in the Indian Ocean in 2004. Simple before-after comparisons tend to support the hypothesis that 'flying the flag' helps attract higher private donations. However, performing a difference-in-difference-in-differences (DDD) approach, we find only weak indications that private donors systematically and strongly preferred NGOs with operations in the region. Extended specifications of the baseline regressions reveal that our major findings are robust. NGO heterogeneity matters in some respects, but the DDD results hold when accounting for proxies of the NGOs' reputation and experience. © 2016 The Author(s). Disasters © Overseas Development Institute, 2016.

  15. A new atlas of temperature and salinity for the North Indian Ocean

    Indian Academy of Sciences (India)

    The most used temperature and salinity climatology for the world ocean, including the Indian Ocean, is the World Ocean Atlas (WOA) (Antonov et al 2006, 2010; Locarnini et al 2006, 2010) because of the vast amount of data used in its preparation. The WOA climatology does not, however, include all the available ...

  16. A tropospheric ozone maximum over the equatorial Southern Indian Ocean

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2012-05-01

    Full Text Available We examine the distribution of tropical tropospheric ozone (O3 from the Microwave Limb Sounder (MLS and the Tropospheric Emission Spectrometer (TES by using a global three-dimensional model of tropospheric chemistry (GEOS-Chem. MLS and TES observations of tropospheric O3 during 2005 to 2009 reveal a distinct, persistent O3 maximum, both in mixing ratio and tropospheric column, in May over the Equatorial Southern Indian Ocean (ESIO. The maximum is most pronounced in 2006 and 2008 and less evident in the other three years. This feature is also consistent with the total column O3 observations from the Ozone Mapping Instrument (OMI and the Atmospheric Infrared Sounder (AIRS. Model results reproduce the observed May O3 maximum and the associated interannual variability. The origin of the maximum reflects a complex interplay of chemical and dynamic factors. The O3 maximum is dominated by the O3 production driven by lightning nitrogen oxides (NOx emissions, which accounts for 62% of the tropospheric column O3 in May 2006. We find the contribution from biomass burning, soil, anthropogenic and biogenic sources to the O3 maximum are rather small. The O3 productions in the lightning outflow from Central Africa and South America both peak in May and are directly responsible for the O3 maximum over the western ESIO. The lightning outflow from Equatorial Asia dominates over the eastern ESIO. The interannual variability of the O3 maximum is driven largely by the anomalous anti-cyclones over the southern Indian Ocean in May 2006 and 2008. The lightning outflow from Central Africa and South America is effectively entrained by the anti-cyclones followed by northward transport to the ESIO.

  17. Distribution of Tritium and {sup 137}CS in South Indian Ocean Waters - Implications of Water Transport Processes

    Energy Technology Data Exchange (ETDEWEB)

    Povinec, P. P.; Jeskovsky, M.; Sykora, I. [Comenius University, Faculty of Mathematics, Physics and Informatics, Bratislava (Slovakia); Aoyama, M. [Meteorological Research Institute, Tsukuba (Japan); Gastaud, J.; Levy, I. [International Atomic Energy Agency, Marine Environment Laboratories (Monaco); Hamajima, Y. [Kanazawa University, Low-Level Radioactivity Laboratory, Nomi (Japan); Hirose, K. [Sophia University, Faculty of Science and Technology, Tokyo (Japan); Sanchez-Cabeza, J. A. [Universitat Autonoma de Barcelona, Bellaterra (Spain)

    2013-07-15

    The World Ocean, and specifically the Indian Ocean, plays a significant role in the better understanding of the climate. The distribution of global fallout {sup 3}H, {sup 14}C, {sup 90}Sr, {sup 129}I and {sup 137}Cs in the seawater of the Indian Ocean, after their main injection from atmospheric nuclear weapons tests during the 1960s, have been investigated. Results obtained in the framework of the SHOTS (Southern Hemisphere Ocean Tracer Studies) project are evaluated and compared with previously published data. The enhanced {sup 3}H and {sup 137}Cs levels observed in the south Indian ocean indicate transport of water masses labelled with these radionuclides from the central Pacific Ocean via the Indonesian Seas to the Indian Ocean. The observed surface gradients and presence of several water masses in the south Indian ocean makes this ocean one of the most dynamic parts of the World ocean. (author)

  18. Coastal biogeochemical processes in the north Indian Ocean (14, S-W)

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Narvekar, P.V.; Desa, E.

    of the region are also shown with the numbers denoting the annual runoff in 10" m3. Due to the proximity to landmasses, the North Indian Ocean is probably af- fected by processes originating at the land-ocean boundary more than any other region. Lndeed... IN TIiE NORTH INDIAN OCEAN tion of contributions by the Indian oceanographic community, most of this infor- mation has been generated by scientists from countries outside this region under international efforts that started with the John Murray...

  19. Variability, interaction and change in the atmosphere-ocean-ecology system of the Western Indian Ocean.

    Science.gov (United States)

    Spencer, T; Laughton, A S; Flemming, N C

    2005-01-15

    Traditional ideas of intraseasonal and interannual climatic variability in the Western Indian Ocean, dominated by the mean cycle of seasonally reversing monsoon winds, are being replaced by a more complex picture, comprising air-sea interactions and feedbacks; atmosphere-ocean dynamics operating over intrannual to interdecadal time-scales; and climatological and oceanographic boundary condition changes at centennial to millennial time-scales. These forcings, which are mediated by the orography of East Africa and the Asian continent and by seafloor topography (most notably in this area by the banks and shoals of the Mascarene Plateau which interrupts the westward-flowing South Equatorial Current), determine fluxes of water, nutrients and biogeochemical constituents, the essential controls on ocean and shallow-sea productivity and ecosystem health. Better prediction of climatic variability for rain-fed agriculture, and the development of sustainable marine resource use, is of critical importance to the developing countries of this region but requires further basic information gathering and coordinated ocean observation systems.

  20. Gravity anomalies over the central Indian ridge between 3 degree S and 11 degree S, Indian Ocean: Segmentation and crustal structure

    Digital Repository Service at National Institute of Oceanography (India)

    Samudrala, K.; KameshRaju, K.A; RamaRao, P.

    High-resolution shipboard geophysical investigations along the Indian Ocean ridge system are sparse especially over the Carlsberg and Central Indian ridges. In the present study, the shipboard gravity and multibeam bathymetry data acquired over a...

  1. The hydromedusae and water masses of the Indian Ocean

    Directory of Open Access Journals (Sweden)

    D. Navas-Pereira

    1991-01-01

    Full Text Available This analysis of distribution and abundance of species of Hydromedusae completes a report (Vannucci & Navas, 1973b on the ecology of Indian Ocean Hydromedusae based on the zooplankton collected during the International Indian Ocean Expedition (IIOE. Distribution and abundance are taken here to be the ecological expression of variability of species in space and time. The aim was to identify the biological signature of below surface water masses that cannot be identified by remote sensing techniques. Selected species were taken as biological units, the oceanic water masses as defined by their T-S and T-O2 diagrammes were taken as the non biological units. Taken together they define different ecosystems of the Indian Ocean. About 45,000 specimens of hydromedusae taken at 480 stations were sorted from 900 plankton samples and all specimens were determined and counted. Several hauls, mostly stratified, were taken with closing nets, but not all contained hydromedusae. The distribution of each species was studied in relation to water salinity, temperature and dissolved oxygen; the limits of ecological tolerance and preference were defined by the environmental characteristics of the layers sampled by the nets and are given for each species. These can be grouped as follows: 1. Deep water species, cold tolerant, often eurytopic; 2. Antarctic species, cold loving, usually stenothermal with preference for low salinity; 3. Indian Ocean Central Water species, with preference for temperature lower than 19ºC and salinity not much higher than 35%o, usually found at sub-surface or intermediate depths, they may spread into the Arabian Sea and Bay of Bengal in surface layers; 4. Indian Ocean Equatorial System species, warm tolerant, usually prefer comparatively low salinity, high temperature and high oxygen content; 5. Bay of Bengal Surface Water species, found in surface layers of the Bay, with preference for low salinity, high temperature and high oxygen content

  2. Assessment of marine weather forecasts over the Indian sector of Southern Ocean

    Science.gov (United States)

    Gera, Anitha; Mahapatra, D. K.; Sharma, Kuldeep; Prakash, Satya; Mitra, A. K.; Iyengar, G. R.; Rajagopal, E. N.; Anilkumar, N.

    2017-09-01

    The Southern Ocean (SO) is one of the important regions where significant processes and feedbacks of the Earth's climate take place. Expeditions to the SO provide useful data for improving global weather/climate simulations and understanding many processes. Some of the uncertainties in these weather/climate models arise during the first few days of simulation/forecast and do not grow much further. NCMRWF issued real-time five day weather forecasts of mean sea level pressure, surface winds, winds at 500 hPa & 850 hPa and rainfall, daily to NCAOR to provide guidance for their expedition to Indian sector of SO during the austral summer of 2014-2015. Evaluation of the skill of these forecasts indicates possible error growth in the atmospheric model at shorter time scales. The error growth is assessed using the model analysis/reanalysis, satellite data and observations made during the expedition. The observed variability of sub-seasonal rainfall associated with mid-latitude systems is seen to exhibit eastward propagations and are well reproduced in the model forecasts. All cyclonic disturbances including the sub-polar lows and tropical cyclones that occurred during this period were well captured in the model forecasts. Overall, this model performs reasonably well over the Indian sector of the SO in medium range time scale.

  3. Madden-Julian Oscillation: Western Pacific and Indian Ocean

    Science.gov (United States)

    Fuchs, Z.; Raymond, D. J.

    2016-12-01

    The MJO has been and still remains a "holy grail" of today's atmospheric science research. Why does the MJO propagate eastward? What makes it unstable? What is the scaling for the MJO, i.e. why does it prefer long wavelengths or planetary wavenumbers 1-3? The MJO has the strongest signal in the Indian ocean and in the West Pacific, but the average vertical structure is very different in each of those basins. We look at the reanalysis/analysis FNL, ERAI vertical structure of temperature and moisture as well as the surface zonal winds for two ocean basins. We also look at data from DYNAMO and TOGA_COARE in great detail (saturation fraction, temperature, entropy, surface zonal winds, gross moist stability, etc). The findings from observations and field projects for the two ocean basins are then compared to a linear WISHE model on an equatorial beta plane. Though linear WISHE has long been discounted as a plausible model for the MJO, the version we have developed explains many of the observed features of this phenomenon, in particular, the preference for large zonal scale, the eastward propagation, the westward group velocity, and the thermodynamic structure. There is no need to postulate large-scale negative gross moist stability, as destabilization occurs via WISHE at long wavelengths only. This differs from early WISHE models because we take a moisture adjustment time scale of order one day in comparison to the much shorter time scales assumed in earlier models. Linear modeling cannot capture all of the features of the MJO, so we are in the process of adding nonlinearity.

  4. Warming of the Indian Ocean threatens eastern and southern African food security but could be mitigated by agricultural development

    Science.gov (United States)

    Funk, Chris C.; Dettinger, Michael D.; Michaelsen, Joel C.; Verdin, James P.; Brown, Molly E.; Barlow, Mathew; Hoell, Andrew

    2008-01-01

    Since 1980, the number of undernourished people in eastern and southern Africa has more than doubled. Rural development stalled and rural poverty expanded during the 1990s. Population growth remains very high, and declining per-capita agricultural capacity retards progress toward Millennium Development goals. Analyses of in situ station data and satellite observations of precipitation have identified another problematic trend: main growing-season rainfall receipts have diminished by ???15% in food-insecure countries clustered along the western rim of the Indian Ocean. Occurring during the main growing seasons in poor countries dependent on rain-fed agriculture, these declines are societally dangerous. Will they persist or intensify? Tracing moisture deficits upstream to an anthropogenically warming Indian Ocean leads us to conclude that further rainfall declines are likely. We present analyses suggesting that warming in the central Indian Ocean disrupts onshore moisture transports, reducing continental rainfall. Thus, late 20th-century anthropogenic Indian Ocean warming has probably already produced societally dangerous climate change by creating drought and social disruption in some of the world's most fragile food economies. We quantify the potential impacts of the observed precipitation and agricultural capacity trends by modeling 'millions of undernourished people' as a function of rainfall, population, cultivated area, seed, and fertilizer use. Persistence of current tendencies may result in a 50% increase in undernourished people by 2030. On the other hand, modest increases in per-capita agricultural productivity could more than offset the observed precipitation declines. Investing in agricultural development can help mitigate climate change while decreasing rural poverty and vulnerability. ?? 2008 by The National Academy of Sciences of the USA.

  5. Warming of the Indian Ocean threatens eastern and southern African food security but could be mitigated by agricultural development.

    Science.gov (United States)

    Funk, Chris; Dettinger, Michael D; Michaelsen, Joel C; Verdin, James P; Brown, Molly E; Barlow, Mathew; Hoell, Andrew

    2008-08-12

    Since 1980, the number of undernourished people in eastern and southern Africa has more than doubled. Rural development stalled and rural poverty expanded during the 1990s. Population growth remains very high, and declining per-capita agricultural capacity retards progress toward Millennium Development goals. Analyses of in situ station data and satellite observations of precipitation have identified another problematic trend: main growing-season rainfall receipts have diminished by approximately 15% in food-insecure countries clustered along the western rim of the Indian Ocean. Occurring during the main growing seasons in poor countries dependent on rain-fed agriculture, these declines are societally dangerous. Will they persist or intensify? Tracing moisture deficits upstream to an anthropogenically warming Indian Ocean leads us to conclude that further rainfall declines are likely. We present analyses suggesting that warming in the central Indian Ocean disrupts onshore moisture transports, reducing continental rainfall. Thus, late 20th-century anthropogenic Indian Ocean warming has probably already produced societally dangerous climate change by creating drought and social disruption in some of the world's most fragile food economies. We quantify the potential impacts of the observed precipitation and agricultural capacity trends by modeling "millions of undernourished people" as a function of rainfall, population, cultivated area, seed, and fertilizer use. Persistence of current tendencies may result in a 50% increase in undernourished people by 2030. On the other hand, modest increases in per-capita agricultural productivity could more than offset the observed precipitation declines. Investing in agricultural development can help mitigate climate change while decreasing rural poverty and vulnerability.

  6. Oceanic geoid and tides derived from GEOS 3 satellite data in the Northwestern Atlantic Ocean

    Science.gov (United States)

    Won, I. J.; Miller, L. S.

    1979-01-01

    Two sets of GEOS 3 altimeter data which fall within about a 2.5-deg width are analyzed for ocean geoid and tides. One set covers a path from Newfoundland to Cuba, and the other a path from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M2, O1, S2, and K1, are derived along the two strips. While the analyses produced convergent solutions for all 40 cases, the uncertainty caused by the linear orbital bias error of the satellite is too large to claim that the solutions represent the true ocean tides in the area. A spot check of the result with the Mode deep-sea tide gauge data shows poor agreement. A positive conclusion of this study is that despite the uncertain orbital error the oceanic geoid obtained through this analysis can improve significantly the short-wavelength structure over existing spherical harmonic geoid models.

  7. Use of Real Time Satellite Infrared and Ocean Color to Produce Ocean Products

    Science.gov (United States)

    Roffer, M. A.; Muller-Karger, F. E.; Westhaver, D.; Gawlikowski, G.; Upton, M.; Hall, C.

    2014-12-01

    Real-time data products derived from infrared and ocean color satellites are useful for several types of users around the world. Highly relevant applications include recreational and commercial fisheries, commercial towing vessel and other maritime and navigation operations, and other scientific and applied marine research. Uses of the data include developing sampling strategies for research programs, tracking of water masses and ocean fronts, optimizing ship routes, evaluating water quality conditions (coastal, estuarine, oceanic), and developing fisheries and essential fish habitat indices. Important considerations for users are data access and delivery mechanisms, and data formats. At this time, the data are being generated in formats increasingly available on mobile computing platforms, and are delivered through popular interfaces including social media (Facebook, Linkedin, Twitter and others), Google Earth and other online Geographical Information Systems, or are simply distributed via subscription by email. We review 30 years of applications and describe how we develop customized products and delivery mechanisms working directly with users. We review benefits and issues of access to government databases (NOAA, NASA, ESA), standard data products, and the conversion to tailored products for our users. We discuss advantages of different product formats and of the platforms used to display and to manipulate the data.

  8. Studying the Indian Ocean Ridge System: Agenda for the new century

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Iyer, S.D.; Banerjee, R.; Drolia, R.K.

    Studies on the Indian Ocean Ridge System, though sporadic, was aimed to map the complete IORS petrologically and tectonically. Three areas are placed for immediate investigation; one in the slow spreading Carlsberg Ridge area, the second, along...

  9. Relationships between Indian summer monsoon rainfall and ice cover over selected oceanic regions

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinathan, C.K.

    The variations in oceanic ice cover at selected polar regions during 1973 to 1987 have been analysed in relation to the seasonal Indian summer monsoon rainfall. The ice cover over the Arctic regions in June has negative relationship (correlation...

  10. Temperature profile data from profiling drifter in the Indian, Southern, and Pacific Ocean (NODC Accession 9700028)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected using the ALACE (Autonomous LAgrangian Circulation Explorer), which is a profiling drifter in the Indian, Southern, and...

  11. Variation in size, morphology and chemical composition of polymetallic nodules from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.; Karisiddaiah, S.M.; Parthiban, G.

    Chemical composition of 613 polymetallic nodules from 150 stations in the Central Indian Ocean Basin (CIOB) are determined and variations in Mn, Fe, Cu, Ni, Co, Zn and moisture content are studied with respect to their size and surface texture...

  12. Tectonic reactivation in the Indian Ocean: Evidences from seamount morphology and manganese nodule characteristics

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Khadge, N.H.

    The Central Indian Ocean Basin (CIOB) was subjected to tectonic reactivation in geological past which is unusual for a basin occurring on an apparently single tectonic plate. ENE-WSW trending latitude parallel zone of reactivation across the central...

  13. Indian Ocean Earthquake and Tsunamis: Food Aid Needs and the U.S. Response

    National Research Council Canada - National Science Library

    Hanrahan, Charles E

    2005-01-01

    ...) in Indonesia set off a series of large tsunamis across the Indian Ocean region. In all, 12 countries were hit by wave surges, with the brunt of the impact in coastal communities in Indonesia, the Maldives, Sri Lanka, and Thailand...

  14. Thermal structure and flow patterns around Seychelles group of Islands (Indian Ocean) during austral autumn

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.; RameshBabu, V.; RameshKumar, M.R.

    Properties of thermal structure in the upper 750 m around the Seychelles group of islands in the Indian Ocean, based on Expendable Bathythermograph (XBT) data collected in March 1984, are presented along with the inferred flow patterns...

  15. ENSO modulation of interannual variability of dust aerosols over the northwest Indian ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banerjee, P.; PrasannaKumar, S.

    Mineral dust is known to affect many aspects of the climate of the north Indian Ocean (IO) However, what controls its interannual variability over this region is largely unknown The authors study the mechanism controlling the interannual variability...

  16. Inter-relationship between nuclei and gross characteristics of manganese nodules, Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Sarkar, C; Iyer, S.D.; Hazra, S.

    More than 200 samples of manganese nodules from the Central Indian Ocean Basin (CIOB) were studied for their different parameters. The study included various aspects such as morphology, texture, mineralogy, and composition of the nodules. The nuclei...

  17. Annual and interannual variation of precipitation over the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Prasad, T.G.

    /month, and the lowest amplitudes are found in the western Indian Ocean, especially off the Arabian and east African coasts. The INSAT and GEOS Precipitation Index (GPI) rainfall estimates correlated reasonably well with the island rainfall data, with correlation...

  18. Determination of vertical velocities in the equatorial part of the western Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Varadachari, V.V.R.

    Using steady state two-dimensional turbulent diffusion equations of salt and heat some important characteristics of vertical circulation in the equatorial part of the Indian Ocean have been evaluated and discussed. Upwelling and sinking velocities...

  19. A Smart Climatology of Evaporation Duct Height and Surface Radar Propagation in the Indian Ocean

    National Research Council Canada - National Science Library

    Twigg, Katherine L

    2007-01-01

    .... We have used existing, civilian, dynamically balanced reanalysis data, for 1970 to 2006, and a state-of-the-art ED model, to produce a spatially and temporally refined EDH climatology for the Indian Ocean (10) and nearby seas...

  20. Western Indian Ocean Journal of Marine Science - Vol 13, No 1 (2014)

    African Journals Online (AJOL)

    View or download the full issue, Untitled () PDF. Table of Contents. Articles. Morphology of the Zambezi River plume in the Sofala Bank, Mozambique · EMAIL ... (Iles Eparses, France) in the Mozambique Channel, South Western Indian Ocean.

  1. North-south diversity of Scolecithricidae species (Copepoda: Calanoida) in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishnan, T.C.; Balachandran, T.

    The effectiveness of north-south hydrographical barriers in restricting the distributions of Scolecithricidae species (Copepoda:Calanoida) in the euphotic zone of the Indian Ocean was studied. Twenty seven species belonging to 7 genera were...

  2. Macrobenthic abundance in the vicinity of spreading ridge environment in Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.

    Macrofaunal communities of the Central Indian Ocean were evaluated for their composition, distribution, abundance and biomass. The fauna comprised of 24 major groups belonging to 15 phyla. The density of macrofauna varied from 30 to 1430 ind.m–2...

  3. Himalayan sedimentary pulses recorded by silicate detritus within a ferromanganese crust from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.; Galy, A.; Sukumaran, N.P.; Parthiban, G.; Volvaiker, A.Y.

    A Central Indian Ocean deep-water seamount hydrogenous ferromanganese crust (SS663-Crust) contains variable (7-23%) amounts of detrital material (silicate-detritus). Taking into account the growth rate of the authigenic component, the accumulation...

  4. Surface currents in the equatorial Indian Ocean during spring and fall - An altimetry based analysis

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, M.K.; Somayajulu, Y.K.

    This communication presents the results of a study aimed at investigating the nature and variability of surface currents in the equatorial Indian Ocean between 5 degrees N and 5 degrees S during spring and fall seasons. Geostrophic surface currents...

  5. The origin of ferro-manganese oxide coated pumice from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Pearce, N.J.G.; Parthiban, G.; Smith, V.C.; Mudholkar, A.V.; Rao, N.R

    Pumice clasts, partially and fully coated with ferro-manganese oxide from the Central Indian Ocean Basin (CIOB) were analysed for major, trace and rare earth elements; and glass and mineral grain chemistry to assess their possible source...

  6. Hydrothermal signature in ferromanganese oxide coatings on pumice from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.; Mascarenhas-Pereira, M.B.L.; Nath, B.N.

    Mineralogical and elemental analyses of 20 ferromanganese (FeMn)-coated pumice samples from the Central Indian Ocean Basin (CIOB) indicate that todorokite is the major mineral phase, whereas vernadite occurs only rarely. Based on major, trace...

  7. Annual mean statistics of the surface fluxes of the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Rao, L.V.G.

    MEAN STATISTICS OF THE SURFACE FLUXES OF THE TROPICAL INDIAN OCEAN (Research Note) M. R. RAMESH KUMAR and L. V. GANGADHARA RAO Physical Oceanography Division, National Institute of Oceanography, Dona Paula, 403004, Goa, India (Received in final...

  8. Benthic disturbance and monitoring experiment in the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, R.; Nath, B.N.

    Environmental impact assessment studies for deep-sea manganese nodule mining have been initiated in the Central indian Ocean Basin since 1995. As a part of the first phase for collecting the benthic baseline data, echosounding, subbottom profiling...

  9. Chaetognath community and their responses to varying environmental factors in the northern Indian ocean.

    Digital Repository Service at National Institute of Oceanography (India)

    Kusum, K.K.; Vineetha, G.; Raveendran, T.V.; Nair, V.R.; Muraleedharan, K.R.; Achuthankutty, C.T.; Joseph, T.

    The ecology of the chaetognath community and its relation to varying environmental factors were studied in the eastern half of the northern Indian Ocean. Analysis of data from two major oceanographic programmes performed over four decades apart...

  10. Thermal structure of the Western Indian Ocean during the southwest monsoon, 1983

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, Y.V.B.; Sarma, M.S.S.; Rao, L.V.G.

    The thermal structure and the variability of heat content of the upper 400 m of the Western Indian Ocean were examined using the expendable bathythermograph (XBT) data collected onboard RV Sagar Kanya during July-August, 1983. Vertical displacement...

  11. Watermass structure in the western Indian Ocean: Part 1. Watermasses and their thermohaline indices

    Digital Repository Service at National Institute of Oceanography (India)

    Sastry, J.S.; Premchand, K.; Murty, C.S.

    The concept of "Indian Ocean Common Watermass" is introduced and its characteristics are defined. The temperature-salinity structures which would result when one, two or more watermasses of different temperature and salinity characteristics...

  12. New ichthyoliths from ferromanganese crusts and nodules from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.

    Ferromanganese encrusted hardgrounds, their intraclasts and the nuclei of manganese nodules collected from the Central Indian Ocean basin have yielded plentiful numbers of ichthyoliths. Forty well-knon ichthyoliths, one new type and 35 new subtypes...

  13. Calcite dissolution along a transect in the western tropical Indian Ocean: A multiproxy approach

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, S.S.; Naidu, P.D.

    Three paleocarbonate ion proxies, size index, planktonic foraminifera shell weight, and calcite crystallinity, have been employed here to a set of core top samples from the western tropical Indian Ocean in the water depth ranges from 1086 to 4730 m...

  14. Compartmental models for assessing the fishery production in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Dalal, S.G.; Parulekar, A.H.

    Compartmental models for assessing the fishery production in the Indian Ocean is discussed. The article examines the theoretical basis on which modern fishery sciences is built. The model shows that, large changes in energy flux from one pathway...

  15. Secondary calcification of planktic foraminifera from the Indian sector of Southern ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mohan, R.; Shetye, S.; Tiwari, M.; AnilKumar, N.

    This study focused on planktic foraminifera in plankton tows and surface sediments from the western Indian sector of Southern Ocean in order to evaluate the potential foraminiferal secondary calcification and/or dissolution in the sediment...

  16. On the semi-diagnostic computation of climatological circulation in the western tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shaji, C.; Rao, A.D.; Dube, S.K.; Bahulayan, N.

    and internal density field on the dynamical balance of circulation in the western tropical Indian Ocean is explained. The climatological temperature and salinity data used to drive the model is found to be hydrodynamically adjusted with surface wind, flow field...

  17. Ocean control of the breeding regime of the sooty tern in the southwest Indian Ocean

    Science.gov (United States)

    Jaquemet, S.; Le Corre, M.; Quartly, G. D.

    2007-01-01

    Food availability, which is often seasonal, is regarded as a key factor in the breeding success of seabirds. In oceanic tropical areas, the resources are mostly patchy and ephemeral at the surface, and the seasonality is less marked than at higher latitudes. Such a situation influences greatly the breeding strategies of the oceanic seabird species. We conducted a comparative study of the breeding phenology of the sooty tern ( Sterna fuscata) in relation to the local and regional oceanographic conditions around the four major colonies (Europa, Juan de Nova, Lys and Bird Islands) of the southwest Indian Ocean. Over the 1997-2003 period, around all the studied locations, the sea-surface temperature (SST) and the chlorophyll concentration in the Mozambique Channel and the Seychelles area showed clear seasonal differences related to the southern climate and the monsoon phenomena. The breeding activity is synchronized at each studied colony, but the timings are very different. Seasonal reproduction occurs in austral winter at Europa and Bird Island and in austral summer at Juan de Nova; at Lys Island the reproduction is non-seasonal. For the seasonal colonies, there is a large monthly change in SST just before the beginning of reproduction, which is a proxy indicating the annual phytoplankton bloom. This variation is accompanied by the development of oceanic features such as fronts that favour aggregation of prey, and may also play an important role in the presence of schools of surface tuna, which are very important for the foraging success of sooty terns. Conversely, around Lys Island the seasonal variations of the marine environment do not lead to pronounced development of oceanic structures, and consequently, the longer-lasting phytoplankton bloom could explain the non-seasonal breeding regime there. Further studies will help discern the advantages and disadvantages of seasonal and non-seasonal reproduction regime in response to unpredictable fluctuations of the

  18. Impact of improved momentum transfer coefficients on the dynamics and thermodynamics of the north Indian Ocean

    Science.gov (United States)

    Parekh, Anant; Gnanaseelan, C.; Jayakumar, A.

    2011-01-01

    Long time series of in situ observations from the north Indian Ocean are used to compute the momentum transfer coefficients over the north Indian Ocean. The transfer coefficients behave nonlinearly for low winds (<4 m/s), when most of the known empirical relations assume linear relations. Impact of momentum transfer coefficients on the upper ocean parameters is studied using an ocean general circulation model. The model experiments revealed that the Arabian Sea and Equatorial Indian Ocean are more sensitive to the momentum transfer coefficients than the Bay of Bengal and south Indian Ocean. The impact of momentum transfer coefficients on sea surface temperature is up to 0.3°C-0.4°C, on mixed layer depth is up to 10 m, and on thermocline depth is up to 15 m. Furthermore, the impact on the zonal current is maximum over the equatorial Indian Ocean (i.e., about 0.12 m/s in May and 0.15 m/s in October; both May and October are the period of Wyrtki jets and the difference in current has potential impact on the seasonal mass transport). The Sverdrup transport has maximum impact in the Bay of Bengal (3 to 4 Sv in August), whereas the Ekman transport has maximum impact in the Arabian Sea (4 Sv during May to July). These highlight the potential impact of accurate momentum forcing on the results from current ocean models.

  19. Nudging Satellite Altimeter Data Into Quasi-Geostrophic Ocean Models

    Science.gov (United States)

    Verron, Jacques

    1992-05-01

    This paper discusses the efficiency of several variants of the nudging technique (derived from the technique of the same name developed by meteorologists) for assimilating altimeter data into numerical ocean models based on quasi-geostrophic formulation. Assimilation experiments are performed with data simulated in the nominal sampling conditions of the Topex-Poseidon satellite mission. Under experimental conditions it is found that nudging on the altimetric sea level is as efficient as nudging on the vorticity (second derivative in space of the dynamic topography), the technique used thus far in studies of this type. The use of altimetric residuals only, instead of the total altimetric sea level signal, is also explored. The critical importance of having an adequate reference mean sea level is largely confirmed. Finally, the possibility of nudging only the signal of sea level tendency (i.e., the successive time differences of the sea level height) is examined. Apart from the barotropic mode, results are not very successful compared with those obtained by assimilating the residuals.

  20. Reconciling plate kinematic and seismic estimates of lithospheric convergence in the central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Bull, J.M.; DeMets, C.; Krishna, K.S.; Sanderson, D.J.; Merkouriev, S.

    The far-field signature of the India-Asia collision and history of uplift in Tibet are recorded by sediment input into the Indian Ocean and the strain accumulation history across the diffuse plate boundary between the Indian and Capricorn plates. We...

  1. Cerium anomaly variations in ferromanganese nodules and crusts from the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Roelandts, I.; Sudhakar, M.; Pluger, W.L.; Balaram, V.

    Fifty analyses of rare earth elements as well as mineralogical studies have been carried out on a suite of manganese nodules and crusts from the Central Indian Basin and the Western Indian Ocean. The aim was to identify the processes controlling...

  2. Indian Ocean circulation changes over the Middle Pleistocene Transition.

    Science.gov (United States)

    Petrick, B.; Auer, G.; De Vleeschouwer, D.; Christensen, B. A.; Stolfi, C.; Reuning, L.; Martinez-Garcia, A.; Haug, G. H.; Bogus, K.

    2017-12-01

    The Mid-Pleistocene Transition (MPT; 1.4 - 0.4 Ma) represents a climatic shift towards climate cycles at a quasi-100-kyr frequency. Although, several high-resolution records covering the MPT from globally distributed archives exist, there is only sparse evidence on changes in heat exchange between the Pacific and Indian Oceans, which represents a crucial part of the global thermohaline circulation (THC). Deciphering the influence of this heat exchange via the Indonesian Throughflow (ITF) is an important step in understanding the causes of the MPT. The Leeuwin Current off Western Australia is directly influenced by the ITF and can therefore be used to reconstruct ITF variability during the MPT. Today, the Leeuwin Current is the only southward flowing eastern boundary current in the southern hemisphere. The onset of the current is unknown but is proposed to have occurred 1 Ma and was likely related to significant changes in ITF dynamics during the MPT We present the first continuous reconstruction of changes in the Leeuwin Current during the MPT using data from IODP Expedition 356 Site U1460. The site is located at 29°S in the path of the current. High sedimentation rates ( 30 cm/ka) at Site U1460 provide the opportunity for high-resolution reconstruction of the MPT. We reconstruct paleoenvironmental variability by combining XRF, organic geochemistry, ICP-MS and XRD data with shipboard data, to reconstruct Leeuwin Current and ITF variability. Initial analyses show clear indications that upwelling off Western Australia intensified during the MPT, indicated by increased primary productivity related to increased nutrient levels, from 900-600 ka. Our results also suggest that the west Australian current (WAC) strengthened during this time supplying cool eutrophic waters from the high southern latitutes to the site. This intensification of the WAC may have had major implications for the Indian Ocean current system, but also the THC at large. This seems to be coupled with

  3. Use of Multiangle Satellite Observations to Retrieve Aerosol Properties and Ocean Color

    Science.gov (United States)

    Martonchik, John V.; Diner, David; Khan, Ralph

    2005-01-01

    A new technique is described for retrieving aerosol over ocean water and the associated ocean color using multiangle satellite observations. Unlike current satellite aerosol retrieval algorithms which only utilize observations at red wavelengths and longer, with the assumption that these wavelengths have a negligible ocean (water-leaving radiance), this new algorithm uses all available spectral bands and simultaneously retrieves both aerosol properties and the spectral ocean color. We show some results of case studies using MISR data, performed over different water conditions (coastal water, blooms, and open water).

  4. 500 kyr of Indian Ocean Walker Circulation Variability Using Foraminiferal Mg/Ca and Stable Isotopes

    Science.gov (United States)

    Groeneveld, J.; Mohtadi, M.; Lückge, A.; Pätzold, J.

    2017-12-01

    The tropical Indian Ocean is a key location for paleoclimate research affected by different oceanographic and atmospheric processes. Annual climate variations are strongly controlled by the Indian and Asian Monsoon characterized by bi-annually reversing trade winds. Inter-annual climate variations in the Walker circulation are caused by the Indian Ocean Dipole and El Niño-Southern Oscillation resulting in either heavy flooding or severe droughts like for example the famine of 2011 in eastern Africa. Oceanographically the tropical western Indian Ocean receives water masses from the Indonesian Gateway area, sub-Antarctic waters that upwell south of the equator, and the outflow waters from the highly saline Red Sea. On the other hand, the tropical western Indian Ocean is a major source for providing water masses to the Agulhas Current system. Although the eastern Indian Ocean has been studied extensively, the tropical western Indian Ocean is still lacking in high quality climate-archives that have the potential to provide important information to understand how the ocean and atmospheric zonal circulation have changed in the past, and possibly will change in the future. Until now there were no long sediment cores available covering several glacial-interglacial cycles in the tropical western Indian Ocean. Core GeoB 12613-1, recovered during RV Meteor Cruise M75/2 east of the island of Pemba off Tanzania, provides an open-ocean core with well-preserved sediments covering the last five glacial-interglacial cycles ( 500 kyr). Mg/Ca and stable isotopes on both surface- and thermocline dwelling foraminifera have been performed to test how changes in sea water temperatures and relative sea water salinity were coupled on orbital time scales. The results are compared with similar records generated for the tropical eastern Indian Ocean in core SO139-74KL off Sumatra. Water column stratification on both sides of the Indian Ocean and the cross-basin gradients in sea water

  5. Performance metrics for the assessment of satellite data products: an ocean color case study

    Science.gov (United States)

    Performance assessment of ocean color satellite data has generally relied on statistical metrics chosen for their common usage and the rationale for selecting certain metrics is infrequently explained. Commonly reported statistics based on mean squared errors, such as the coeffic...

  6. Mismo field experiment in the equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Masumoto, Y.; Kuroda, Y.; Katsumata, M.; Mizuno, K.; Takayabu, Y.N.; Yoshizaki, M.; Shareef, A.; Fujiyoshi, Y.; McPhaden, M.J.; Murty, V.S.N.; Shirooka, R; Yasunaga, K.; Yamada, H.; Sato, N.; Ushiyama, T.; Moteki, Q.; Seiki, A.; Fujita, M.; Ando, K.; Hase, H.; Ueki, I; Horii, T.; Yokoyama, C.; Miyakawa, T.

    MISMO FIELD EXPERIMENT IN THE EQUATORIAL INDIAN OCEAN * b y Ku n i o yo n e y a m a , yu K i o ma s u m o t o , yo s h i f u m i Ku r o d a , ma s a K i Ka t s u m a t a , Ke i s u K e mi z u n o , yu K a r i n. ta K a y a b u , ma s a n o r i... yo s h i z a K i , al i sh a r e e f, ya s u s h i fu j i y o s h i , mi c h a e l j. mcPh a d e n , V. s. n. mu r t y , ry u i c h i sh i r o o K a , Ka z u a K i ya s u n a g a , hi r o y u K i ya m a d a , na o K i sa t o , to m o K i us...

  7. Multiple ciguatoxins present in Indian Ocean reef fish.

    Science.gov (United States)

    Hamilton, Brett; Hurbungs, Mira; Jones, Alun; Lewis, Richard J

    2002-09-01

    Optimised gradient reversed-phase high-performance liquid chromatography electrospray ionisation mass spectrometry (LC/MS) methods, in combination with a [3H]-brevetoxin binding assay (RLB), revealed multiple ciguatoxins in a partially purified extract of a highly toxic Lutjanus sebae (red emperor) from the Indian Ocean. Two major ciguatoxins of 1140.6 Da (I-CTX-1 and -2) and two minor ciguatoxins of 1156.6 Da (I-CTX-3 and -4) were identified. Accurate mass analysis revealed that I-CTX-1 and -2 and Caribbean C-CTX-1 had indistinguishable masses (1140.6316 Da, at 0.44 ppm resolution). Toxicity estimated from LC/MS/RLB responses indicated that I-CTX-1 and -2 were both approximately 60% the potency of Pacific ciguatoxin-1 (P-CTX-1). In contrast to ciguatoxins of the Pacific where the more oxidised ciguatoxins are more potent, I-CTX-3 and -4 were approximately 20% of P-CTX-1 potency. Interconversion in dilute acid or on storage, typical of spiroketal and hemiketal functionality found in P-CTXs and C-CTXs, respectively, was not observed to occur between I-CTX-1 and -2. The ratio of CTX-1 and -2 varied depending on the fish extract being analysed. These results suggest that I-CTX-1 and -2 may arise from separate dinoflagellate precursors that may be oxidatively biotransformed to I-CTX-3 and -4 in fish.

  8. Predicting Kenya Short Rains Using the Indian Ocean SST

    Science.gov (United States)

    Peng, X.; Albertson, J. D.; Steinschneider, S.

    2017-12-01

    The rainfall over the Eastern Africa is charaterized by the typical bimodal monsoon system. Literatures have shown that the monsoon system is closely connected with the large-scale atmospheric motion which is believed to be driven by sea surface temperature anomalies (SSTA). Therefore, we may make use of the predictability of SSTA in estimating future Easter Africa monsoon. In this study, we tried predict the Kenya short rains (Oct, Nov and Dec rainfall) based on the Indian Ocean SSTA. The Least Absolute Shrinkage and Selection Operator (LASSO) regression is used to avoid over-fitting issues. Models for different lead times are trained using a 28-year training set (2006-1979) and are tested using a 10-year test set (2007-2016). Satisfying prediciton skills are achieved at relatively long lead times (i.e., 8 and 10 months) in terms of correlation coefficient and sign accuracy. Unlike some of the previous work, the prediction models are obtained from a data-driven method. Limited predictors are selected for each model and can be used in understanding the underlying physical connection. Still, further investigation is needed since the sampling variability issue cannot be excluded due to the limited sample size.

  9. Ocean Optics Protocols for Satellite Ocean Color Sensor Validation. Volume 2; Revised

    Science.gov (United States)

    Mueller, James L. (Editor); Fargion, Giulietta S. (Editor); Trees, C.; Austin, R. W.; Pietras, C. (Editor); Hooker, S.; Holben, B.; McClain, Charles R.; Clark, D. K.; Yuen, M.

    2002-01-01

    This document stipulates protocols for measuring bio-optical and radiometric data for the SIMBIOS Project. It supersedes the earlier version, and is organized into four parts: Introductory Background, Instrument Characteristics, Field Measurements and Data Analysis, Data Reporting and Archival. Changes in this revision include the addition of three new chapters: (1) Fundamental Definitions, Relationships and Conventions; (2) MOBY, A Radiometric Buoy for Performance Monitoring and Vicarious Calibration of Satellite Ocean Color Sensors: Measurement and Data Analysis Protocols; and (3) Normalized Water-Leaving Radiance and Remote Sensing Reflectance: Bidirectional Reflectance and Other Factors. Although the present document represents another significant, incremental improvement in the ocean optics protocols, there are several protocols that have either been overtaken by recent technological progress, or have been otherwise identified as inadequate. Revision 4 is scheduled for completion sometime in 2003. This technical report is not meant as a substitute for scientific literature. Instead, it will provide a ready and responsive vehicle for the multitude of technical reports issued by an operational Project. The contributions are published as submitted, after only minor editing to correct obvious grammatical or clerical errors.

  10. Ocean Optics Protocols for Satellite Ocean Color Sensor Validation. Volume 1; Revised

    Science.gov (United States)

    Mueller, James L. (Editor); Fargion, Giulietta (Editor); Mueller, J. L.; Trees, C.; Austin, R. W.; Pietras, C.; Hooker, S.; Holben, B.; McClain, Charles R.; Clark, D. K.; hide

    2002-01-01

    This document stipulates protocols for measuring bio-optical and radiometric data for the SIMBIOS Project. It supersedes the earlier version, and is organized into four parts: Introductory Background, Instrument Characteristics, Field Measurements and Data Analysis, Data Reporting and Archival. Changes in this revision include the addition of three new chapters: (1) Fundamental Definitions, Relationships and Conventions; (2) MOBY, A Radiometric Buoy for Performance Monitoring and Vicarious Calibration of Satellite Ocean Color Sensors: Measurement and Data Analysis Protocols; and (3) Normalized Water-Leaving Radiance and Remote Sensing Reflectance: Bidirectional Reflectance and Other Factors. Although the present document represents another significant, incremental improvement in the ocean optics protocols, there are several protocols that have either been overtaken by recent technological progress, or have been otherwise identified as inadequate. Revision 4 is scheduled for completion sometime in 2003. This technical report is not meant as a substitute for scientific literature. Instead, it will provide a ready and responsive vehicle for the multitude of technical reports issued by an operational Project. The contributions are published as submitted, after only minor editing to correct obvious grammatical or clerical errors.

  11. Phylogeography of the crown-of-thorns starfish in the Indian Ocean.

    Directory of Open Access Journals (Sweden)

    Catherine Vogler

    Full Text Available Understanding the limits and population dynamics of closely related sibling species in the marine realm is particularly relevant in organisms that require management. The crown-of-thorns starfish Acanthaster planci, recently shown to be a species complex of at least four closely related species, is a coral predator infamous for its outbreaks that have devastated reefs throughout much of its Indo-Pacific distribution.In this first Indian Ocean-wide genetic study of a marine organism we investigated the genetic structure and inferred the paleohistory of the two Indian Ocean sister-species of Acanthaster planci using mitochondrial DNA sequence analyses. We suggest that the first of two main diversification events led to the formation of a Southern and Northern Indian Ocean sister-species in the late Pliocene-early Pleistocene. The second led to the formation of two internal clades within each species around the onset of the last interglacial. The subsequent demographic history of the two lineages strongly differed, the Southern Indian Ocean sister-species showing a signature of recent population expansion and hardly any regional structure, whereas the Northern Indian Ocean sister-species apparently maintained a constant size with highly differentiated regional groupings that were asymmetrically connected by gene flow.Past and present surface circulation patterns in conjunction with ocean primary productivity were identified as the processes most likely to have shaped the genetic structure between and within the two Indian Ocean lineages. This knowledge will help to understand the biological or ecological differences of the two sibling species and therefore aid in developing strategies to manage population outbreaks of this coral predator in the Indian Ocean.

  12. Trends in the Indian Ocean Climatology due to anthropogenic induced global warming

    CSIR Research Space (South Africa)

    Meyer, AA

    2009-09-01

    Full Text Available clearly show that due to global warming the South West Indian Ocean Climatology has been changing and that this changing trend will continue into the future as global warming continues. The impacts of regional oceanic climate change on the regions coastal...

  13. Processes of interannual mixed layer temperature variability in the thermocline ridge of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    PraveenKumar, B.; Vialard, J.; Lengaigne, M.; Murty, V.S.N.; Foltz, G.R.; McPhaden, M.J.; Pous, S.; Montegut , C.deB.

    , Brest Center, Pointe du Diable, B.P. 70 Plouzane 29280, France Corresponding author address: B Praveen Kumar Modelling and Ocean observations Group (MOG) Indian National Centre for Ocean Information Services (INCOIS), Hyderabad. India... SST after the end of El Niño, and to prolong its regional climate impacts (the so-called Indian Ocean “capacitor” effect). Murtugudde et al. (2000) and Du et al. (2009) did not focus on the TRIO region, but showed that a combination of vertical...

  14. The ecology of scattering layer biota around Indian Ocean seamounts and islands

    OpenAIRE

    Boersch-Supan, Philipp Hanno

    2014-01-01

    The waters of the open ocean constitute the largest living space on Earth but despite its obvious significance to the biosphere, the open ocean remains an unexplored frontier. With a regional focus on the Indian Ocean, this thesis investigates (i) the distribution of pelagic biota on basin scales, (ii) the effect of abrupt topography on pelagic biota and their predator-prey relationships, and (iii) the use of genetic techniques to elucidate population connectivity and dispersal of pelag...

  15. BAROMETRIC PRESSURE and Other Data from UNKNOWN and Other Platforms From Indian Ocean from 19910701 to 19940222 (NODC Accession 9400142)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in the Indian Ocean. Data were collected from Ship BARUNA JAYA I. The data were collected...

  16. PRESSURE - WATER and Other Data from UNKNOWN From Indian Ocean from 19060101 to 19891231 (NODC Accession 9100054)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data in the Indian Ocean from ORSTOM (France); 26,000 profiles from years 1906 thru 1989. Most appear to be derived from bathythermographs,...

  17. STOMACH CONTENT OF THREE TUNA SPECIES IN THE EASTERN INDIAN OCEAN

    Directory of Open Access Journals (Sweden)

    Bram Setyadji

    2012-12-01

    Full Text Available Feeding habit of tuna in Indian Ocean has been described around Sri Lanka, Indian Waters, Andaman Sea, western Indian Ocean (Seychelles Islands, western equatorial Indian Ocean whereas the tunas feeding habit study in Eastern Indian Oceanis merely in existence. The purpose of this study is to investigate the stomach content of three tuna species (bigeye tuna, yellowfin tuna, and skipjack tuna, apex predator in the southern part of Eastern Indian Ocean. The study was conducted in March – April, 2010 on the basis of catches of commercial tuna longline vessel based in Port of Benoa. A total of 53 individual fishes were collected, consisting of bigeye tuna (Thunnus obesus, yellowfin tuna (Thunnus albacores, and skipjack tuna (Katsuwonus pelamis. Stomach specimens were collected and analyzed.Analysis was conducted on the basis of index of preponderance method. The diet of the three tuna species showed fishes as the main diet (56–82%, followed by cephalopods (squids as the complementary diet (0–8%, and crustaceans (shrimps as the additional diet (2–4%. Fish prey composed of 6 families i.e. Alepisauridae, Bramidae, Carangidae, Clupeidae, Engraulidae, and Scombridae.

  18. Seasonality in the relationship between El Nino and Indian Ocean dipole

    Energy Technology Data Exchange (ETDEWEB)

    Roxy, Mathew [Centro-Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); Indian Institute of Tropical Meteorology, Centre for Climate Change Research, Pune (India); Gualdi, Silvio; Navarra, Antonio [Centro-Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy); Lee Drbohlav, Hae-Kyung [University of Hawaii at Manoa, International Pacific Research Center, Honolulu, HI (United States)

    2011-07-15

    The seasonal change in the relationship between El Nino and Indian Ocean dipole (IOD) is examined using the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40), and the twentieth century simulations (20c3m) from the Geophysical Fluid Dynamics Laboratory Coupled Model, version 2.1. It is found that, both in ERA-40 and the model simulations, the correlation between El Nino (Nino3 index) and the eastern part of the IOD (90-110 E; 10 S-equator) is predominantly positive from January to June, and then changes to negative from July to December. Correlation maps of atmospheric and oceanic variables with respect to the Nino3 index are constructed for each season in order to examine the spatial structure of their seasonal response to El Nino. The occurrence of El Nino conditions during January to March induces low-level anti-cyclonic circulation anomalies over the southeastern Indian Ocean, which counteracts the climatological cyclonic circulation in that region. As a result, evaporation decreases and the southeastern Indian Ocean warms up as the El Nino proceeds, and weaken the development of a positive phase of an IOD. This warming of the southeastern Indian Ocean associated with the El Nino does not exist past June because the climatological winds there develop into the monsoon-type flow, enhancing the anomalous circulation over the region. Furthermore, the development of El Nino from July to September induces upwelling in the southeastern Indian Ocean, thereby contributing to further cooling of the region during the summer season. This results in the enhancement of a positive phase of an IOD. Once the climatological circulation shifts from the boreal summer to winter mode, the negative correlation between El Nino and SST of the southeastern Indian Ocean changes back to a positive one. (orig.)

  19. Foraminifera Population from South Africa Coast Line (Indian and Atlantic Oceans

    Directory of Open Access Journals (Sweden)

    Engin Meriç

    2014-11-01

    Full Text Available Cape Town is the second-largest city of the Republic of South Africa. Research is conducted in 3 different stations: Maori Bay, which lies in the southwest of Cape Town, and Pyramid Rock and Partridge Points which lies in the False Bay, southeast part of Cape Town. Samples are taken from young sediments at 10.00 and 20.00 m depths, and collected by scuba-diving method. The aim of the study is to investigate the living benthic foraminifera assemblages in the Atlantic Ocean, and to compare these assemblages with the southeastern part of the Atlantic Ocean, the Arabian Sea, Indian Ocean and Western Pacific assemblages. Moreover, the aim of the study is to determine whether there are any benthic foraminifera forms reaching to the Mediterranean from Pacific Ocean, Indian Ocean or Red Sea via Suez Channel.

  20. Soldiers, Artisans, Cultivators and Revolutionaries: The Movement of Sikhs in the Indian Ocean

    Directory of Open Access Journals (Sweden)

    Anjali Gera Roy

    2012-06-01

    Full Text Available The geography of Punjab, a land-locked region divided between India and Pakistan, makes it an unlikely player in oceanic sojourns. But imperial interventions in Punjab in the middle of the 19th century triggered movements from Punjab that inserted this region in the littoral narrative of the Indian Ocean. Unlike the movements of lascars and traders, who have been central to the revisionist histories of the Indian Ocean, those from Punjab have not featured in oceanic dialogues. The absence of Sikhs in Indian Ocean studies is largely due to the silence of Sikh soldiers, skilled craftsmen and cultivators with largely rural roots who were uprooted to strange lands. The confusion of Sikhs with Hindus, Muslims and, even Afghans, in the colonial era, as well as the classification of Punjabi Muslims as Pakistani in the post-colonial, further problematizes the Sikh migration narrative. Drawing on a wide range of official and unofficial historical sources, this essay argues that twin developments in Punjab, namely the construction of Sikhs as ‘a martial race’ and their integration into the imperial capitalist economy, connects the movements of soldiers and policemen to Shanghai, Hong Kong, the Straits Settlements and Kenya with those of skilled artisans to Mombasa and Uganda. Keywords: Sikhs, Indian Ocean, labour migration, cultural identity

  1. Sea-level-rise trends off the Indian coasts during the last two decades

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.; Nidheesh, A.G.; Lengaigne, M.

    The present communication discusses sea-level-rise trends in the north Indian Ocean, particularly off the Indian coasts, based on estimates derived from satellite altimeter and tide-gauge data. Altimeter data analysis over the 1993–2012 period...

  2. Beach recovery after 2004 Indian Ocean tsunami from Phang-nga, Thailand

    Science.gov (United States)

    Choowong, Montri; Phantuwongraj, Sumet; Charoentitirat, Thasinee; Chutakositkanon, Vichai; Yumuang, Sombat; Charusiri, Punya

    2009-03-01

    The 2004 Indian Ocean tsunami devastated the coastal areas along the Andaman western coast of Thailand and left unique physical evidence of its impact, including the erosional landforms of the pre-tsunami topography. Here we show the results from monitoring the natural recovery of beach areas at Khuk Khak and Bang Niang tidal channels of Khao Lak area, Phang-nga, Thailand. A series of satellite images before and after the tsunami event was employed for calculating the beach area and locating the position of the changed shoreline. Field surveys to follow-up the development of the post-tsunami beach area were conducted from 2005 to 2007 and the yearly beach profile was measured in 2006. As a result, the scoured beach areas where the tidal channel inlets were located underwent continuous recovery. The return of post-tsunami sediments within the beach zone was either achieved by normal wind and wave processes or during the storm surges in the rainy season. Post-2004 beach sediments were derived mainly from near offshore sources. The present situation of the beach zone has almost completed reversion back to the equilibrium stage and this has occurred within 2 years after the tsunami event. We suggest these results provide a better understanding of the geomorphological process involved in beach recovery after severe erosion such as by tsunami events.

  3. Indian Ocean floor deformation induced by the Reunion plume rather than the Tibetan Plateau

    Science.gov (United States)

    Iaffaldano, G.; Davies, D. R.; DeMets, C.

    2018-05-01

    The central Indian Ocean is considered the archetypal diffuse oceanic plate boundary. Data from seismic stratigraphy and deep-sea drilling indicate that the contractional deformation of the Indian Ocean lithosphere commenced at 15.4-13.9 Ma, but experienced a sharp increase at 8-7.5 Ma. This has been maintained through to the present day, with over 80% of the shortening accrued over the past 8 Myr. Here we build on previous efforts to refine the form, timing and magnitude of the regional plate-motion changes by mitigating the noise in reconstructed Indian and Capricorn plate motions relative to Somalia. Our noise-mitigated reconstructions tightly constrain the significant speed up of the Capricorn plate over the past 8 Myr and demonstrate that the history of the Indian Ocean floor deformation cannot be explained without this plate-motion change. We propose that the Capricorn plate-motion change is driven by an increase in the eastward-directed asthenospheric flow associated with the adjacent Reunion plume, and quantitatively demonstrate the viability of this hypothesis. Our inference is supported by volcanic age distributions along the Reunion hotspot track, the anomalously high residual bathymetry of the Central Indian Ridge, full-waveform seismic tomography of the underlying asthenosphere and geochemical observations from the Central Indian Ridge. These findings challenge the commonly accepted link between the deformation of the Indian Ocean floor and the Tibetan Plateau's orogenic evolution and demonstrate that temporal variations in upwelling mantle flow can drive major tectonic events at the Earth's surface.

  4. Marine aerosol distribution and variability over the pristine Southern Indian Ocean

    Science.gov (United States)

    Mallet, Paul-Étienne; Pujol, Olivier; Brioude, Jérôme; Evan, Stéphanie; Jensen, Andrew

    2018-06-01

    This paper presents an 8-year (2005-2012 inclusive) study of the marine aerosol distribution and variability over the Southern Indian Ocean, precisely in the area { 10 °S - 40 °S ; 50 °E - 110 °E } which has been identified as one of the most pristine regions of the globe. A large dataset consisting of satellite data (POLDER, CALIOP), AERONET measurements at Saint-Denis (French Réunion Island) and model reanalysis (MACC), has been used. In spite of a positive bias of about 0.05 between the AOD (aerosol optical depth) given by POLDER and MACC on one hand and the AOD measured by AERONET on the other, consistent results for aerosol distribution and variability over the area considered have been obtained. First, aerosols are mainly confined below 2km asl (above sea level) and are dominated by sea salt, especially in the center of the area of interest, with AOD ≤ 0 . 1. This zone is the most pristine and is associated with the position of the Mascarene anticyclone. There, the direct radiative effect is assessed around - 9 Wm-2 at the top of the atmosphere and probability density functions of the AOD s are leptokurtic lognormal functions without any significant seasonal variation. It is also suggested that the Madden-Jullian oscillation impacts sea salt emissions in the northern part of the area considered by modifying the state of the ocean surface. Finally, this area is surrounded in the northeast and the southwest by seasonal Australian and South African intrusions (AOD > 0.1) ; throughout the year, the ITCZ seems to limit continental contaminations from Asia. Due to the long period of time considered (almost a decade), this paper completes and strengthens results of studies based on observations performed during previous specific field campaigns.

  5. Global ocean tides through assimilation of oceanographic and altimeter satellite data in a hydrodynamic model

    Science.gov (United States)

    Leprovost, Christian; Mazzega, P.; Vincent, P.

    1991-01-01

    Ocean tides must be considered in many scientific disciplines: astronomy, oceanography, geodesy, geophysics, meteorology, and space technologies. Progress in each of these disciplines leads to the need for greater knowledge and more precise predictions of the ocean tide contribution. This is particularly true of satellite altimetry. On one side, the present and future satellite altimetry missions provide and will supply new data that will contribute to the improvement of the present ocean tide solutions. On the other side, tidal corrections included in the Geophysical Data Records must be determined with the maximum possible accuracy. The valuable results obtained with satellite altimeter data thus far have not been penalized by the insufficiencies of the present ocean tide predictions included in the geophysical data records (GDR's) because the oceanic processes investigated have shorter wavelengths than the error field of the tidal predictions, so that the residual errors of the tidal corrections are absorbed in the empirical tilt and bias corrections of the satellite orbit. For future applications to large-scale oceanic phenomena, however, it will no longer be possible to ignore these insufficiencies.

  6. Differential Heating in the Indian Ocean Differentially Modulates Precipitation in the Ganges and Brahmaputra Basins

    Directory of Open Access Journals (Sweden)

    Md Shahriar Pervez

    2016-10-01

    Full Text Available Indo-Pacific sea surface temperature dynamics play a prominent role in Asian summer monsoon variability. Two interactive climate modes of the Indo-Pacific—the El Niño/Southern Oscillation (ENSO and the Indian Ocean dipole mode—modulate the amount of precipitation over India, in addition to precipitation over Africa, Indonesia, and Australia. However, this modulation is not spatially uniform. The precipitation in southern India is strongly forced by the Indian Ocean dipole mode and ENSO. In contrast, across northern India, encompassing the Ganges and Brahmaputra basins, the climate mode influence on precipitation is much less. Understanding the forcing of precipitation in these river basins is vital for food security and ecosystem services for over half a billion people. Using 28 years of remote sensing observations, we demonstrate that (i the tropical west-east differential heating in the Indian Ocean influences the Ganges precipitation and (ii the north-south differential heating in the Indian Ocean influences the Brahmaputra precipitation. The El Niño phase induces warming in the warm pool of the Indian Ocean and exerts more influence on Ganges precipitation than Brahmaputra precipitation. The analyses indicate that both the magnitude and position of the sea surface temperature anomalies in the Indian Ocean are important drivers for precipitation dynamics that can be effectively summarized using two new indices, one tuned for each basin. These new indices have the potential to aid forecasting of drought and flooding, to contextualize land cover and land use change, and to assess the regional impacts of climate change.

  7. Differential heating in the Indian Ocean differentially modulates precipitation in the Ganges and Brahmaputra basins

    Science.gov (United States)

    Pervez, Md Shahriar; Henebry, Geoffrey M.

    2016-01-01

    Indo-Pacific sea surface temperature dynamics play a prominent role in Asian summer monsoon variability. Two interactive climate modes of the Indo-Pacific—the El Niño/Southern Oscillation (ENSO) and the Indian Ocean dipole mode—modulate the amount of precipitation over India, in addition to precipitation over Africa, Indonesia, and Australia. However, this modulation is not spatially uniform. The precipitation in southern India is strongly forced by the Indian Ocean dipole mode and ENSO. In contrast, across northern India, encompassing the Ganges and Brahmaputra basins, the climate mode influence on precipitation is much less. Understanding the forcing of precipitation in these river basins is vital for food security and ecosystem services for over half a billion people. Using 28 years of remote sensing observations, we demonstrate that (i) the tropical west-east differential heating in the Indian Ocean influences the Ganges precipitation and (ii) the north-south differential heating in the Indian Ocean influences the Brahmaputra precipitation. The El Niño phase induces warming in the warm pool of the Indian Ocean and exerts more influence on Ganges precipitation than Brahmaputra precipitation. The analyses indicate that both the magnitude and position of the sea surface temperature anomalies in the Indian Ocean are important drivers for precipitation dynamics that can be effectively summarized using two new indices, one tuned for each basin. These new indices have the potential to aid forecasting of drought and flooding, to contextualize land cover and land use change, and to assess the regional impacts of climate change.

  8. Clustering Indian Ocean Tropical Cyclone Tracks by the Standard Deviational Ellipse

    Directory of Open Access Journals (Sweden)

    Md. Shahinoor Rahman

    2018-05-01

    Full Text Available The standard deviational ellipse is useful to analyze the shape and the length of a tropical cyclone (TC track. Cyclone intensity at each six-hour position is used as the weight at that location. Only named cyclones in the Indian Ocean since 1981 are considered for this study. The K-means clustering algorithm is used to cluster Indian Ocean cyclones based on the five parameters: x-y coordinates of the mean center, variances along zonal and meridional directions, and covariance between zonal and meridional locations of the cyclone track. Four clusters are identified across the Indian Ocean; among them, only one cluster is in the North Indian Ocean (NIO and the rest of them are in the South Indian Ocean (SIO. Other characteristics associated with each cluster, such as wind speed, lifespan, track length, track orientation, seasonality, landfall, category during landfall, total accumulated cyclone energy (ACE, and cyclone trend, are analyzed and discussed. Cyclone frequency and energy of Cluster 4 (in the NIO have been following a linear increasing trend. Cluster 4 also has a higher number of landfall cyclones compared to other clusters. Cluster 2, located in the middle of the SIO, is characterized by the long track, high intensity, long lifespan, and high accumulated energy. Sea surface temperature (SST and outgoing longwave radiation (OLR associated with genesis of TCs are also examined in each cluster. Cyclone genesis is co-located with the negative OLR anomaly and the positive SST anomaly. Localized SST anomalies are associated with clusters in the SIO; however, TC geneses of Cluster 4 are associated with SSTA all over the Indian Ocean (IO.

  9. Temperature profile data from STD/CTD casts from the MELVILLE from the Indian Ocean for the International Decade of Ocean Exploration / Geochemical Ocean Section Study (IDOE/GEOSECS) project, 06 December 1977 to 21 April 1978 (NODC Accession 8200055)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature and salinity profile data were collected using STD/CTD casts from MELVILLE from the Indian Ocean from December 6, 1977 to April 21, 1978. Data were...

  10. American Indian Telecommunications Satellite Demonstration Project. Summary Report.

    Science.gov (United States)

    Lyndon B. Johnson Space Center, Houston, TX.

    The technical feasibility of voice and television communication within and between tribes, between tribes and federal agencies, and between educational institutions and tribes was demonstrated by broadcasts which took place April 10, 12, and 14, 1978, with equipment located at four sites: Crow Agency, Montana; All- Indian Culture Center, New…

  11. Occurrence of @iNeogloboquadrina pachyderma@@ new subspecies in the shelf-slope sediments of northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Setty, M.G.A.P.

    ~'N in the Bay of Bengal. Studies of hydrological conditions in the Indian Ocean reveal that the Subtropical Subsurface Water Mass is traceable as far north as the Gulf of Aden, and the Indian Ocean Deep Bottom Water Mass originating in the deepest...

  12. Quaternary radiolarian faunal changes in the tropical Indian Ocean: Inferences to paleomonsoonal oscillation of the 10 degrees S hydrographic front

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, S.M.; Fernandes, A.A.

    The northern Indian Ocean is characterized by three distinct surface water masses, i.e. (1) highly saline (greater than 34.5 ppt) Arabian Sea, (2) low saline (less than 34.5 ppt) Bay of Bengal and (3) a moderate salinity Indian Ocean watermass south...

  13. Key to the identification of larvae and postlarvae of the penaeid prawns (Decapoda: Penaeidea) of the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Paulinose, V.T.

    Some of the major criteria for identifying the larvae and early postlarvae of the penaeid prawns of the Indian Ocean are presented based on the study on material collected during the International Indian Ocean Expedition (1960-65). The key also...

  14. Dissolved strontium and calcium levels in the tropical Indian Ocean

    Science.gov (United States)

    Steiner, Zvi; Sarkar, Amit; Turchyn, Alexandra

    2017-04-01

    Measurements of seawater alkalinity and dissolved calcium concentrations along oceanic transects are often used to calculate calcium carbonate precipitation and dissolution rates. Given that the distribution coefficient of strontium in CaCO3 varies greatly between different groups of organisms, adding precise measurements of dissolved strontium concentrations provides opportunities to also track relative contributions of these different groups to the regional CaCO3 cycle. However, there are several obstacles to this approach. These obstacles include unresolved systematic discrepancies between seawater calcium and alkalinity data, very large analytical noise around the calcium concentration measurements and the unconstrained role of acantharia (radiolarian precipitating SrSO4 skeletons) in the marine strontium cycle. During the first cruise of the second International Indian Ocean Expedition (IIOE-2) water samples were collected along 67°E from 9°N to 5°S to explore the dissolution rate of calcium carbonate in the water. The dissolution rate can be calculated by combining measurements of water column potential alkalinity with calcium and strontium concentrations measured by ICP-OES and calcium concentration measurements using isotope dilution thermal ionization mass spectrometry (ID-TIMS). CaCO3 mineral saturation state calculated using pH and total alkalinity suggests that along 67°E, the aragonite saturation horizon lays at depth of 500 m on both sides of the equator. Across the cruise transect, dissolved strontium concentrations increase by 2-3% along the thermocline suggesting rapid recycling of strontium rich phases. This is particularly evident just below the thermocline at 8-9°N and below 1000 m water depth, south of the equator. The deep, southern enrichment in strontium does not involve a change in the Sr/Ca ratio, suggesting that this strontium enrichment is related to CaCO3 dissolution. In contrast, in the intermediate waters of the northern part of

  15. Coastal sea level response to the tropical cyclonic forcing in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mehra, P.; Soumya, M.; Vethamony, P.; Vijaykumar, K.; Nair, T.M.B.; Agarvadekar, Y.; Jyoti, K.; Sudheesh, K.; Luis, R.; Lobo, S.; Halmalkar, B.

    –173, 2015 www.ocean-sci.net/11/159/2015/ doi:10.5194/os-11-159-2015 © Author(s) 2015. CC Attribution 3.0 License. Coastal sea level response to the tropical cyclonic forcing in the northern Indian Ocean P. Mehra1, M. Soumya1, P. Vethamony1, K. Vijaykumar1, T.... Note: sea level data at Colombo, Kochi, Karachi, Chabahar, Jask, Masirah, Minocoy and Hanimaadhoo are downloaded from www.gloss-sealevel.org and are shown with red stars. (Time is in Indian standard time (IST).) land locations of India are provided...

  16. Emergence of melioidosis in the Indian Ocean region: Two new cases and a literature review.

    Directory of Open Access Journals (Sweden)

    Nicolas Allou

    2017-12-01

    Full Text Available Melioidosis is a disease caused by bacteria called B. pseudomallei. Infections can develop after contact with standing water. This disease can reach all the organs and especially the lungs. It is associated with a high mortality rate (up to 50%. Melioidosis is endemic in northern Australia and in Southeast Asia. Nevertheless, B. pseudomallei may be endemic in the Indian Ocean region and in Madagascar in particular, so clinicians and microbiologists should consider acute melioidosis as a differential diagnosis in the Indian Ocean region, in particular from Madagascar.

  17. New evidence on the sequence of deglacial warming in the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.; Govil, P.

    . Quat. Sci., vol.25(7); 2010; 1138-1143 A New Evidence on Sequence of Deglacial Warming in the Tropical Indian Ocean P. Divakar Naidu 1 , Pawan Govil 1,2 1 National Institute of Oceanography, Dona Paula 403 004, Goa, India 2 National Centre... relative timing of abrupt climate warming in the tropics versus the high latitudes should be known. Therefore, the present communication is aimed to address the start of deglaciation in the Indian Ocean based on sea surface temperature (SST) derived from...

  18. Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, I.; Vialard, J.; Lengaigne, M.; Han, W.; Mc; Durand, F.; Muraleedharan, P.M.

    version: Geophys. Res. Lett., vol.40(21); 2013; 5740-5744 Origins of wind-driven intraseasonal sea level variations in the North Indian Ocean coastal waveguide I. Suresh1, J. Vialard2, M. Lengaigne2, W. Han3, J. McCreary4, F. Durand5, P.M. Muraleedharan1... reversing winds. These wind variations drive seasonal equatorial Kelvin and Rossby wave responses. The seasonal equatorial Kelvin waves propagate into the North Indian Ocean (hereafter NIO) as coastal Kelvin waves [McCreary et al., 1993]. As a result...

  19. Intraseasonal response of the northern Indian Ocean coastal waveguide to the Madden-Julian Oscillation

    Digital Repository Service at National Institute of Oceanography (India)

    Vialard, J.; Shenoi, S.S.C.; Mc; Shankar, D.; Durand, F.; Fernando, V.; Shetye, S.R.

    Author version: Geophys. Res. Lett.: 36(14); 2009; doi:10.1029/2009GL038450; 5 pp Intraseasonal response of Northern Indian Ocean coastal waveguide to the Madden-Julian Oscillation J. Vialard 1 2 , S.S.C Shenoi 2 , J.P. McCreary 3 , D. Shankar 2... involving both equatorial wave dynamics and coastal wave propagation around the perimeter of the northern Indian Ocean [McCreary et al., 1993]. The East India Coastal Current (EICC), for example, is strongly influenced by remote wind forcing from...

  20. Minima of interannual sea-level variability in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shankar, D.; Aparna, S.G.; Mc; Suresh, I.; Neetu, S.; Durand, F.; Shenoi, S.S.C.; Al Saafani, M.A.

    of interannual sea-level variability in the Indian Ocean D. Shankar a ,S.G.Aparna a ,J.P.McCreary b ,I.Suresh a , S. Neetu a ,F.Durand c , S. S. C. Shenoi a , M. A. Al Saafani a,d a National Institute of Oceanography,Dona Paula, Goa 403 004, India. b SOEST..., for example,the reviewby Schott and McCreary, 2001) implies that changes in sea level can be forced at a given loca- tion by winds blowing elsewhere earlier in the season. This phenomenon, called remote forcing, “merges the equatorial Indian Ocean, the Arabian...

  1. The Influence of Air-Sea Fluxes on Atmospheric Aerosols During the Summer Monsoon Over the Tropical Indian Ocean

    Science.gov (United States)

    Zavarsky, Alex; Booge, Dennis; Fiehn, Alina; Krüger, Kirstin; Atlas, Elliot; Marandino, Christa

    2018-01-01

    During the summer monsoon, the western tropical Indian Ocean is predicted to be a hot spot for dimethylsulfide emissions, the major marine sulfur source to the atmosphere, and an important aerosol precursor. Other aerosol relevant fluxes, such as isoprene and sea spray, should also be enhanced, due to the steady strong winds during the monsoon. Marine air masses dominate the area during the summer monsoon, excluding the influence of continentally derived pollutants. During the SO234-2/235 cruise in the western tropical Indian Ocean from July to August 2014, directly measured eddy covariance DMS fluxes confirm that the area is a large source of sulfur to the atmosphere (cruise average 9.1 μmol m-2 d-1). The directly measured fluxes, as well as computed isoprene and sea spray fluxes, were combined with FLEXPART backward and forward trajectories to track the emissions in space and time. The fluxes show a significant positive correlation with aerosol data from the Terra and Suomi-NPP satellites, indicating a local influence of marine emissions on atmospheric aerosol numbers.

  2. Evaluating Surface Radiation Fluxes Observed From Satellites in the Southeastern Pacific Ocean

    Science.gov (United States)

    Pinker, R. T.; Zhang, B.; Weller, R. A.; Chen, W.

    2018-03-01

    This study is focused on evaluation of current satellite and reanalysis estimates of surface radiative fluxes in a climatically important region. It uses unique observations from the STRATUS Ocean Reference Station buoy in a region of persistent marine stratus clouds 1,500 km off northern Chile during 2000-2012. The study shows that current satellite estimates are in better agreement with buoy observations than model outputs at a daily time scale and that satellite data depict well the observed annual cycle in both shortwave and longwave surface radiative fluxes. Also, buoy and satellite estimates do not show any significant trend over the period of overlap or any interannual variability. This verifies the stability and reliability of the satellite data and should make them useful to examine El Niño-Southern Oscillation variability influences on surface radiative fluxes at the STRATUS site for longer periods for which satellite record is available.

  3. Optimized coral reconstructions of the Indian Ocean Dipole: An assessment of location and length considerations

    Science.gov (United States)

    Abram, Nerilie J.; Dixon, Bronwyn C.; Rosevear, Madelaine G.; Plunkett, Benjamin; Gagan, Michael K.; Hantoro, Wahyoe S.; Phipps, Steven J.

    2015-10-01

    The Indian Ocean Dipole (IOD; or Indian Ocean Zonal Mode) is a coupled ocean-atmosphere climate oscillation that has profound impacts on rainfall distribution across the Indian Ocean region. Instrumental records provide a reliable representation of IOD behavior since 1958, while coral reconstructions currently extend the IOD history back to 1846. Large fluctuations in the number and intensity of positive IOD events over time are evident in these records, but it is unclear to what extent this represents multidecadal modulation of the IOD or an anthropogenically forced change in IOD behavior. In this study we explore the suitability of coral records from single-site locations in the equatorial Indian Ocean for capturing information about the occurrence and magnitude of positive IOD (pIOD) events. We find that the optimum location for coral reconstructions of the IOD occurs in the southeastern equatorial Indian Ocean, along the coast of Java and Sumatra between ~3 and 7°S. Here the strong ocean cooling and atmospheric drying during pIOD events are unambiguously recorded in coral oxygen isotope records, which capture up to 50% of IOD variance. Unforced experiments with coupled climate models suggest that potential biases in coral estimates of pIOD frequency are skewed toward overestimating pIOD recurrence intervals and become larger with shorter reconstruction windows and longer pIOD recurrence times. Model output also supports the assumption of stationarity in sea surface temperature relationships in the optimum IOD location that is necessary for paleoclimate reconstructions. This study provides a targeted framework for the future generation of paleoclimate records, including optimized coral reconstructions of past IOD variability.

  4. Moho depth variations over the Maldive Ridge and adjoining Arabian and Central Indian Basins, Western Indian Ocean, from three dimensional inversion of gravity anomalies

    Science.gov (United States)

    Kunnummal, Priyesh; Anand, S. P.; Haritha, C.; Rama Rao, P.

    2018-05-01

    Analysis of high resolution satellite derived free air gravity data has been undertaken in the Greater Maldive Ridge (GMR) (Maldive Ridge, Deep Sea Channel, northern limit of Chagos Bank) segment of the Chagos Laccadive Ridge and the adjoining Arabian and Central Indian Basins. A Complete Bouguer Anomaly (CBA) map was generated from the Indian Ocean Geoidal Low removed Free Air Gravity (hereinafter referred to as "FAG-IOGL") data by incorporating Bullard A, B and C corrections. Using the Parker method, Moho topography was initially computed by inverting the CBA data. From the CBA the Mantle Residual Gravity Anomalies (MRGA) were computed by incorporating gravity effects of sediments and lithospheric temperature and pressure induced anomalies. Further, the MRGA was inverted to get Moho undulations from which the crustal thickness was also estimated. It was found that incorporating the lithospheric thermal and pressure anomaly correction has provided substantial improvement in the computed Moho depths especially in the oceanic areas. But along the GMR, there was not much variation in the Moho thickness computed with and without the thermal and pressure gravity correction implying that the crustal thickness of the ridge does not depend on the oceanic isochrones used for the thermal corrections. The estimated Moho depths in the study area ranges from 7 km to 28 km and the crustal thickness from 2 km to 27 km. The Moho depths are shallower in regions closer to Central Indian Ridge in the Arabian Basin i.e., the region to the west of the GMR is thinner compared to the region in the east (Central Indian Basin). The thickest crust and the deepest Moho are found below the N-S trending GMR segment of the Chagos-Laccadive Ridge. Along the GMR the crustal thickness decreases from north to south with thickness of 27 km below the Maldives Ridge reducing to ∼9 km at 3°S and further increasing towards Chagos Bank. Even though there are similarities in crustal thickness between

  5. Satellite-based Calibration of Heat Flux at the Ocean Surface

    Science.gov (United States)

    Barron, C. N.; Dastugue, J. M.; May, J. C.; Rowley, C. D.; Smith, S. R.; Spence, P. L.; Gremes-Cordero, S.

    2016-02-01

    Model forecasts of upper ocean heat content and variability on diurnal to daily scales are highly dependent on estimates of heat flux through the air-sea interface. Satellite remote sensing is applied to not only inform the initial ocean state but also to mitigate errors in surface heat flux and model representations affecting the distribution of heat in the upper ocean. Traditional assimilation of sea surface temperature (SST) observations re-centers ocean models at the start of each forecast cycle. Subsequent evolution depends on estimates of surface heat fluxes and upper-ocean processes over the forecast period. The COFFEE project (Calibration of Ocean Forcing with satellite Flux Estimates) endeavors to correct ocean forecast bias through a responsive error partition among surface heat flux and ocean dynamics sources. A suite of experiments in the southern California Current demonstrates a range of COFFEE capabilities, showing the impact on forecast error relative to a baseline three-dimensional variational (3DVAR) assimilation using Navy operational global or regional atmospheric forcing. COFFEE addresses satellite-calibration of surface fluxes to estimate surface error covariances and links these to the ocean interior. Experiment cases combine different levels of flux calibration with different assimilation alternatives. The cases may use the original fluxes, apply full satellite corrections during the forecast period, or extend hindcast corrections into the forecast period. Assimilation is either baseline 3DVAR or standard strong-constraint 4DVAR, with work proceeding to add a 4DVAR expanded to include a weak constraint treatment of the surface flux errors. Covariance of flux errors is estimated from the recent time series of forecast and calibrated flux terms. While the California Current examples are shown, the approach is equally applicable to other regions. These approaches within a 3DVAR application are anticipated to be useful for global and larger

  6. Satellite Tidal Magnetic Signals Constrain Oceanic Lithosphere-Asthenosphere Boundary Earth Tomography with Tidal Magnetic Signals

    Science.gov (United States)

    Grayver, Alexander V.; Schnepf, Neesha R.; Kuvshinov, Alexey V.; Sabaka, Terence J.; Chandrasekharan, Manoj; Olsen, Niles

    2016-01-01

    The tidal flow of electrically conductive oceans through the geomagnetic field results in the generation of secondary magnetic signals, which provide information on the subsurface structure. Data from the new generation of satellites were shown to contain magnetic signals due to tidal flow; however, there are no reports that these signals have been used to infer subsurface structure. Here we use satellite-detected tidal magnetic fields to image the global electrical structure of the oceanic lithosphere and upper mantle down to a depth of about 250 km. The model derived from more than 12 years of satellite data reveals an Approximately 72 km thick upper resistive layer followed by a sharp increase in electrical conductivity likely associated with the lithosphere-asthenosphere boundary, which separates colder rigid oceanic plates from the ductile and hotter asthenosphere.

  7. Living planktonic foraminifera of the Wadge bank, Northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, K.K.; Jayalakshmy, K.V.; Panikkar, B.M.; Kutty, M.K.

    Twenty three species of living planktonic Foraminifera belonging to 11 genera have been studied from the Wadge Bank area off southern tip of the Indian peninsula. The fauna is characterized by species such as Globigerinoides conglobatus, G...

  8. Tectonic setting of the Seychelles, Mascarene and Amirante Plateaus in the Western Equatorial Indian Ocean

    International Nuclear Information System (INIS)

    Mart, Y.

    1988-01-01

    A system of marine plateaus occurs in the western equatorial Indian Ocean, forming an arcuate series of wide and shallow banks with small islands in places. The oceanic basins that surround the Seychelles - Amirante region are of various ages and reflect a complex seafloor spreading pattern. The structural analysis of the Seychelle - Amirante - Mascarene region reflects the tectonic evolution of the western equatorial Indian Ocean. It is suggested that due to the seafloor spreading during a tectonic stage, the Seychelles continental block drifted southwestwards to collide with the oceanic crust of the Mascarene Basin, forming an elongated folded structure at first, and then a subduction zone. The morphological similarity, the lithological variability and the different origin of the Seychelles Bank, the Mascarene Plateau and the Amirante Arc emphasizes the significant convergent effects of various plate tectonic processes on the development of marine plateaus

  9. Impact of sinking carbon flux on accumulation of deep-ocean carbon in the Northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, V.V.S.S.; DileepKumar, M.; Saino, T.

    calculations using 14 C activity arises from the separation of natural 90 Biogeochemistry (2007) 82:89–100 123 and bomb-produced 14 C. Rubin and Key (2002) proposed the potential alkalinity method to achieve the separation. However, they found anomalous scatter... in the relationship between 14 C and potential alkalinity caused by data from the northern Indian Ocean (north of equator) and attributed that to the possible transportation of bomb radiocarbon, as carbonate particles from the surface ocean to the sediment...

  10. On the choice of orbits for an altimetric satellite to study ocean circulation and tides

    Science.gov (United States)

    Parke, Michael E.; Stewart, Robert H.; Farless, David L.; Cartwright, David E.

    1987-01-01

    The choice of an orbit for satellite altimetric studies of the ocean's circulation and tides requires an understanding of the orbital characteristics that influence the accuracy of the satellite's measurements of sea level and the temporal and spatial distribution of the measurements. The orbital characteristics that influence accurate calculations of the satellite's position as a function of time are examined, and the pattern of ground tracks laid down on the ocean's surface as a function of the satellite's altitude and inclination is studied. The results are used to examine the aliases in the measurements of surface geostrophic currents and tides. Finally, these considerations are used to specify possible orbits that may be useful for the upcoming Topex/Poseidon mission.

  11. Regal phylogeography: Range-wide survey of the marine angelfish Pygoplites diacanthus reveals evolutionary partitions between the Red Sea, Indian Ocean, and Pacific Ocean.

    Science.gov (United States)

    Coleman, Richard R; Eble, Jeffrey A; DiBattista, Joseph D; Rocha, Luiz A; Randall, John E; Berumen, Michael L; Bowen, Brian W

    2016-07-01

    The regal angelfish (Pygoplites diacanthus; family Pomacanthidae) occurs on reefs from the Red Sea to the central Pacific, with an Indian Ocean/Rea Sea color morph distinct from a Pacific Ocean morph. To assess population differentiation and evaluate the possibility of cryptic evolutionary partitions in this monotypic genus, we surveyed mtDNA cytochrome b and two nuclear introns (S7 and RAG2) in 547 individuals from 15 locations. Phylogeographic analyses revealed four mtDNA lineages (d=0.006-0.015) corresponding to the Pacific Ocean, the Red Sea, and two admixed lineages in the Indian Ocean, a pattern consistent with known biogeographic barriers. Christmas Island in the eastern Indian Ocean had both Indian and Pacific lineages. Both S7 and RAG2 showed strong population-level differentiation between the Red Sea, Indian Ocean, and Pacific Ocean (ΦST=0.066-0.512). The only consistent population sub-structure within these three regions was at the Society Islands (French Polynesia), where surrounding oceanographic conditions may reinforce isolation. Coalescence analyses indicate the Pacific (1.7Ma) as the oldest extant lineage followed by the Red Sea lineage (1.4Ma). Results from a median-joining network suggest radiations of two lineages from the Red Sea that currently occupy the Indian Ocean (0.7-0.9Ma). Persistence of a Red Sea lineage through Pleistocene glacial cycles suggests a long-term refuge in this region. The affiliation of Pacific and Red Sea populations, apparent in cytochrome b and S7 (but equivocal in RAG2) raises the hypothesis that the Indian Ocean was recolonized from the Red Sea, possibly more than once. Assessing the genetic architecture of this widespread monotypic genus reveals cryptic evolutionary diversity that merits subspecific recognition. We recommend P.d. diacanthus and P.d. flavescens for the Pacific and Indian Ocean/Red Sea forms. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Surface freshwater from Bay of Bengal runoff and Indonesian throughflow in the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, D.; Raj, B.; Shenoi, S.S.C.

    ]); monthly evaporation from the Southampton Oceanography Centre (SOC) data (Josey et al. [1998]), and monthly 2openbulletby 2openbulletsurface currents in the tropical Indian Ocean, based on 1985-2002 trajecto- ries of drogued WOCE drifters (Shenoi et al..., Deep-Sea Re- search II, 50, 2111?2127, 2003. Josey, S. A., E. C. Kent, and P. K. Taylor, The Southampton Oceanography Centre (SOC) Ocean - Atmosphere Heat, Mo- mentum and Freshwater Flux Atlas, Tech. Rep. 6, Southamp- ton Oceanography Centre, 1998...

  13. Biological oceanography across the Southern Indian Ocean – basinscale trends in the zooplankton community

    DEFF Research Database (Denmark)

    Jonasdottir, Sigrun; Nielsen, Torkel Gissel; Borg, Christian Marc Andersen

    2013-01-01

    We present a study on the protozooplankton 45 mm and copepods larger than 50 mm at a series of contrasting stations across the Southern Indian Ocean (SIO). Numerically, over 80% of the copepod community across the transect was less than 650 mm in size, dominated by nauplii, and smaller copepods...... stations. Secondary production was low (carbon specific egg production o0.14 d1) but typical for food limited oligotrophic oceans...

  14. Simulation of solar array slewing of Indian remote sensing satellite

    Science.gov (United States)

    Maharana, P. K.; Goel, P. S.

    The effect of flexible arrays on sun tracking for the IRS satellite is studied. Equations of motion of satellites carrying a rotating flexible appendage are developed following the Newton-Euler approach and utilizing the constrained modes of the appendage. The drive torque, detent torque and friction torque in the SADA are included in the model. Extensive simulations of the slewing motion are carried out. The phenomena of back-stepping, step-missing, step-slipping and the influences of array flexibility in the acquisition mode are observed for certain combinations of parameters.

  15. Challenges for present and future estimates of anthropogenic carbon in the Indian Ocean

    Science.gov (United States)

    Goyet, C.; Touratier, F.

    One of the main challenges we face today is to determine the evolution of the penetration of anthropogenic CO2 into the Indian Ocean and its impacts on marine and human life. Anthropogenic CO2 reaches the ocean via air-sea interactions as well as riverine inputs. It is then stored in the ocean and follows the oceanic circulation. As the carbon dioxide from the atmosphere penetrates into the sea, it reacts with water and acidifies the ocean. Consequently, the whole marine ecosystem is perturbed, thus potentially affecting the food web, which has, in turn, a direct impact on seafood supply for humans. Naturally, this will mainly affect the growing number of people living in coastal areas. Although anthropogenic CO2 in the ocean is identical with natural CO2 and therefore cannot be detected alone, many approaches are available today to estimate it. Since most of the results of these methods are globally in agreement, here we chose one of these methods, the tracer using oxygen, total inorganic carbon, and total alkalinity (TrOCA) approach, to compute the 3-D distribution of the anthropogenic CO2 concentrations throughout the Indian Ocean. The results of this distribution clearly illustrate the contrast between the Arabian Sea and the Bay of Bengal. They further show the importance of the southern part of this ocean that carries some anthropogenic CO2 at great depths. In order to determine the future anthropogenic impacts on the Indian Ocean, it is urgent and necessary to understand the present state. As the seawater temperature increases, how and how fast will the ocean circulation change? What will the impacts on seawater properties be? Many people are living on the bordering coasts, how will they be affected?

  16. Advanced payload concepts and system architecture for emerging services in Indian National Satellite Systems

    Science.gov (United States)

    Balasubramanian, E. P.; Rao, N. Prahlad; Sarkar, S.; Singh, D. K.

    2008-07-01

    Over the past two decades Indian Space Research Organization (ISRO) has developed and operationalized satellites to generate a large capacity of transponders for telecommunication service use in INSAT system. More powerful on-board transmitters are built to usher-in direct-to-home broadcast services. These have transformed the Satcom application scenario in the country. With the proliferation of satellite technology, a shift in the Indian market is witnessed today in terms of demand for new services like Broadband Internet, Interactive Multimedia, etc. While it is imperative to pay attention to market trends, ISRO is also committed towards taking the benefits of technological advancement to all round growth of our population, 70% of which dwell in rural areas. The initiatives already taken in space application related to telemedicine, tele-education and Village Resource Centres are required to be taken to a greater height of efficiency. These targets pose technological challenges to build a large capacity and cost-effective satellite system. This paper addresses advanced payload concepts and system architecture along with the trade-off analysis on design parameters in proposing a new generation satellite system capable of extending the reach of the Indian broadband structure to individual users, educational and medical institutions and enterprises for interactive services. This will be a strategic step in the evolution of INSAT system to employ advanced technology to touch every human face of our population.

  17. Air-sea interaction over the Indian Ocean due to variations in the Indonesian throughflow

    Science.gov (United States)

    Wajsowicz, R. C.

    The effects of the Indonesian throughflow on the upper thermocline circulation and surface heat flux over the Indian Ocean are presented for a 3-D ocean model forced by two different monthly wind-stress climatologies, as they show interesting differences, which could have implications for long-term variability in the Indian and Australasian monsoons. The effects are determined by contrasting a control run with a run in which the throughflow is blocked by an artificial land-bridge across the exit channels into the Indian Ocean. In the model forced by ECMWF wind stresses, there is little impact on the annual mean surface heat flux in the region surrounding the throughflow exit straits, whereas in the model forced by SSM/I-based wind stresses, a modest throughflow of less than 5 ×106 m3s-1 over the upper 300 m induces an extra 10-50 Wm-2 output. In the SSM/I-forced model, there is insignificant penetration of the throughflow into the northern Indian Ocean. However, in the ECMWF-forced model, the throughflow induces a 5-10 Wm-2 reduction in heat input into the ocean, i.e., an effective output, over the Somali Current in the annual mean. These differences are attributed to differences in the strength and direction of the Ekman transport of the ambient flow, and the vertical structure of the transport and temperature anomalies associated with the throughflow. In both models, the throughflow induces a 5-30 Wm-2 increase in net output over a broad swathe of the southern Indian Ocean, and a reduction in heat output of 10-60 Wm-2 in a large L-shaped band around Tasmania. Effective increases in throughflow-induced net output reach up to 40 (60) Wm-2 over the Agulhas Current retroflection in the ECMWF (SSM/I)-forced model. Seasonal variations in the throughflow's effect on the net surface heat flux are attributed to seasonal variations in the ambient circulation of the Indian Ocean, specifically in coastal upwelling along the south Javan, west Australian, and Somalian coasts

  18. Towards a merged satellite and in situ fluorescence ocean chlorophyll product

    OpenAIRE

    Lavigne, H.; D'Ortenzio, F.; Claustre, H.; Poteau, A.

    2012-01-01

    Understanding the ocean carbon cycle requires a precise assessment of phytoplankton biomass in the oceans. In terms of numbers of observations, satellite data represents the largest available data set. However, as they are limited to surface waters, they have to be merged with in situ observations. Amongst the in situ data, fluorescence profiles constitute the greatest data set available, because fluorometers operate routinely on oceanographic cruise since the seventies. Nevertheless,...

  19. Ocean tidal signals in observatory and satellite magnetic measurements

    DEFF Research Database (Denmark)

    Maus, S.; Kuvshinov, A.

    2004-01-01

    , and P1 periods turn out to be dominated by unrelated external fields. In contrast, observed lunar M2 and N2 tidal signals are in fair agreement with predictions from motional induction. The lunar diurnal O1 signal, visible at some observatories, could be caused by ocean flow but disagrees in amplitude...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-08-15

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

  1. Moisture flux divergence over the tropical Indian Ocean using INSAT 1B data

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Rao, L.V.G.

    /plain; charset=UTF-8 PROCEEDINGS OF THE TENTH ASIAN CONFERENCE ON REMOTE SENSING NOV. 23-29. 1989 KUAlA LUMPUR. MALAYSIA ACRS 1989 ASIAN CONFERENCE ON REMOTE SENSING .IM)~SroREFLUX DIVERGENCE OVER THE TROPICAL INDIAN OCEAN USING INSAT 18 DATA H. R...

  2. Wave climatology of the Indian Ocean derived from altimetry and wave model

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.; Rao, L.V.G.; Kumar, R.; Sarkar, A.; Mohan, M.; Sudheesh, K.; Karthikeyan, S.B.

    are found to be low compared to model values. As expected, central Indian Ocean region is found to have higher waves, generally swells, generated by strong winds prevailing over there in all seasons. In July, the entire Arabian Sea is under the influence...

  3. Latitudinal range of epiplanktonic Cahetognatha and Ostracoda in the western tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Madhupratap, M.

    An account of the chaetognath and ostracod species obtained from zooplankton samples collected along a transect in the Western Indian Ocean between 9 degrees N-20 degrees S and 57 degrees 18'-68 degrees 43'E in January-February 1981 is given...

  4. Aerosol properties over the Indian Ocean Experiment (INDOEX) campaign area retrieved from ATSR-2

    NARCIS (Netherlands)

    Robles-Gonzalez, C.; Leeuw, G.de; Decae, R.; Kusmierczyk-Michulec, J.T.; Stammes, P.

    2006-01-01

    Aerosol retrieved algorithms for ATSR-2 have been applied over land and water using data from the Indian Ocean Experiment (INDOEX) Intensive Field Phase (IFP) in February and March 1999. The goal was the extension of the ATSR-2 algorithms, developed for application over the U.S. east coast and

  5. Dissolved petroleum hydrocarbon concentrations in some regions of the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    SenGupta, R.; Qasim, S.Z.; Fondekar, S.P.; Topgi, R.S.

    Dissolved petroleum hydrocarbons were measured in some parts of the Northern Indian Ocean using UV bsorbance technique with a clean up step. The concentration of oil ranged from 0.6 to 26.5 mu gl. Higher values were recorded along the oil tanker...

  6. Hydraena Kugelann, 1794 (Coleoptera, Hydraenidae from the Seychelles, Indian Ocean, with description of a new species

    Directory of Open Access Journals (Sweden)

    Manfred A. Jäch

    2016-10-01

    Full Text Available Hydraena matyoti sp. n. (Coleoptera, Hydraenidae is described from the Seychelles, Indian Ocean. Hydraena mahensis Scott, 1913 is redescribed. The latter is here recorded from La Digue for the first time. A key to the species of the genus Hydraena Kugelann, 1794 of the Seychelles is presented.

  7. Hydraena Kugelann, 1794 (Coleoptera, Hydraenidae) from the Seychelles, Indian Ocean, with description of a new species.

    Science.gov (United States)

    Jäch, Manfred A; Delgado, Juan A

    2016-01-01

    Hydraena matyoti sp. n. (Coleoptera, Hydraenidae) is described from the Seychelles, Indian Ocean. Hydraena mahensis Scott, 1913 is redescribed. The latter is here recorded from La Digue for the first time. A key to the species of the genus Hydraena Kugelann, 1794 of the Seychelles is presented.

  8. Evidence of a southward eddy corridor in the South-West Indian ocean

    CSIR Research Space (South Africa)

    Ansorge, IJ

    2015-09-01

    Full Text Available Mesoscale eddies and meanders have been shown to be one of the dominant sources of flow variability in the world s ocean. One example of an isolated eddy hotspot is the South-West Indian Ridge (SWIR). Several investigations have shown that the SWIR...

  9. The evolution of the Indian Ocean parrots (Psittaciformes): extinction, adaptive radiation and eustacy.

    Science.gov (United States)

    Kundu, S; Jones, C G; Prys-Jones, R P; Groombridge, J J

    2012-01-01

    Parrots are among the most recognisable and widely distributed of all bird groups occupying major parts of the tropics. The evolution of the genera that are found in and around the Indian Ocean region is particularly interesting as they show a high degree of heterogeneity in distribution and levels of speciation. Here we present a molecular phylogenetic analysis of Indian Ocean parrots, identifying the possible geological and geographical factors that influenced their evolution. We hypothesise that the Indian Ocean islands acted as stepping stones in the radiation of the Old-World parrots, and that sea-level changes may have been an important determinant of current distributions and differences in speciation. A multi-locus phylogeny showing the evolutionary relationships among genera highlights the interesting position of the monotypic Psittrichas, which shares a common ancestor with the geographically distant Coracopsis. An extensive species-level molecular phylogeny indicates a complex pattern of radiation including evidence for colonisation of Africa, Asia and the Indian Ocean islands from Australasia via multiple routes, and of island populations 'seeding' continents. Moreover, comparison of estimated divergence dates and sea-level changes points to the latter as a factor in parrot speciation. This is the first study to include the extinct parrot taxa, Mascarinus mascarinus and Psittacula wardi which, respectively, appear closely related to Coracopsis nigra and Psittacula eupatria. Copyright © 2011 Elsevier Inc. All rights reserved.

  10. Population Genetic Status of the Western Indian Ocean: What do we ...

    African Journals Online (AJOL)

    The Western Indian Ocean (WIO) is faced with increasing evidence of degradation and effective management initiatives are needed to curtail the environmental decline. The management of the WIO region can therefore benefit from the information that population genetics can provide. Extensive literature searches revealed ...

  11. Western Indian Ocean Journal of Marine Science - Vol 9, No 1 (2010)

    African Journals Online (AJOL)

    Coastal Marine Pollution in Dar es Salaam (Tanzania) relative to Recommended Environmental Quality Targets for the Western Indian Ocean · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. JF Machiwa, 17-30 ...

  12. Monthly mean wind stress along the coast of the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.; Shenoi, S.S.C.; Antony, M.K.; Krishnakumar, V.

    Monthly-mean wind stress and its longshore and offshore components have been computed using the bulk aerodynamic method for each of a string of 36 two-degree-latitude by two-degree-longitude squares along the coast of the north Indian Ocean...

  13. Sensitivity experiments with an adaptation model of circulation of western tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Bahulayan, N.; Shaji, C.; Rao, A.D.; Dube, S.K.

    circulation at 10 m depth is controlled by both wind stress and sea surface topography. Circulation at 50 m depth is mainly controlled by thermohaline forcing and sea surface topography. The current speed in the western tropical Indian Ocean is of the order...

  14. Seabed topography and distribution of manganese nodules in the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Kodagali, V.N.

    in number in all the topographic environments. Mn/Fe ratio was least (2.2) for nodules from hill taps whereas it was maximum for those from the plains (4.4). Cu+Ni+Co compositioin varied antipathetically with nodule abundance in the Central Indian Ocean....

  15. Equatorial Indian Ocean productivity during the last 33 kyr and possible linkage to Westerly Jet variability

    Digital Repository Service at National Institute of Oceanography (India)

    Punyu, V.R.; Banakar, V.K.; Garg, A.

    The top 1 m radiocarbon dated section of a 5.6 m long sediment core retrieved from the Equatorial Indian Ocean is studied for productivity changes in response to climate variability that have taken place during the last ~33 kyr. The robust...

  16. The NOW regional coupled model: Application to the tropical Indian Ocean climate and tropical cyclone activity

    Digital Repository Service at National Institute of Oceanography (India)

    Samson, G.; Masson, S.; Lengaigne, M.; Keerthi, M.G.; Vialard, J.; Pous, S.; Madec, G.; Jourdain, N.C.; Jullien, S.; Menkes, C.; Marchesiello, P.

    with the Indian Ocean Dipole (IOD) and the delayed basin-wide warming/cooling induced by the El Nino Southern Oscillation (ENSO). The timing of IOD occurrence in the ~ model generally matches that of the observed events, confirming the influence of ENSO on the IOD...

  17. Seasonal Variation of Diurnal Cycle of Rainfall in the Eastern Equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Pednekar, S.; Katsumata, M.; Antony, M.K.; Kuroda, Y.; Unnikrishnan, A.S.

    The diurnal cycle of rainfall over the eastern equatorial Indian Ocean is studied for the period 23rd October 2001 to 31st October 2003 using the hourly data from the Triton buoy positioned at 1.5°S and 90°E. An analysis of the active and weak...

  18. Physical properties, morphology and petrological characteristics of pumices from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.; Ilangovan, D.

    About 400 pumice clasts collected from the Central Indian Ocean Basin (CIOB) were studied for their morphology and classified based on their shape and size. A majority of the samples range between less than 1 cm and 36 cm and in the Zinggs shape...

  19. Mixed layer depth and thermocline climatology of the Arabian Sea and western equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Prasad, T.G.; Bahulayan, N.

    A band of zonally oriented ridge of mixed layer depth and thermocline base extending from African Coast to the Central Indian Ocean is observed between 5 degrees S and 10 degrees S throughout hte year. Mixed layer depth and thermocline base deepen...

  20. Western Indian Ocean Journal of Marine Science - Vol 6, No 2 (2008)

    African Journals Online (AJOL)

    Western Indian Ocean Journal of Marine Science. ... Assessment of Heavy Metal Pollution in Sediment and Polychaete Worms from the Mzinga Creek and Ras Dege Mangrove Ecosystems, Dar es Salaam, Tanzania · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT.

  1. Morphological variations in the polymetallic nodules from selected stations in the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.

    Polymetallic nodules from the Central Indian Ocean largely range in size from 2 to 6 cm. The smaller nodules (4 cm) are subspheroidal to spheroidal in shape and with the increase in size, nodules become more discoidal and elongated. The size...

  2. The heat and moisture budgets of the atmosphere over central equatorial Indian Ocean during summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Gopalakrishna, V.V.; RameshBabu, V.; Sastry, J.S.

    The heat and moisture budgets of the atmosphere (surface to 100 mb) over the central equatorial Indian Ocean (2 degrees N to 2 degrees S; 76 degrees E to 80 degrees E) have been investigated utilising the surface and upper air data collected...

  3. Macrobenthic standing stock in the nodule areas of Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pavithran, S.; Ingole, B.S.

    Diversity, distribution and standing stock of macrofauna in the nodule areas of Central Indian Ocean Basin (CIOB) were studied during April 2003. The density ranged between 22 to 132 no.m super(-2) (mean: 55 + or - 37 SD, n=25) and biomass ranged...

  4. Western Indian Ocean Journal of Marine Science - Vol 11, No 1 (2012)

    African Journals Online (AJOL)

    Using an ecosystem model to evaluate fisheries management options to mitigate climate change impacts in western Indian Ocean coral reefs · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Carlos Ruiz Sebastián, Tim R. McClanahan, 77-86 ...

  5. Validity of zooplankton biomass estimates and energy equivalent in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Dalal, S.G.; Parulekar, A.H.

    , as deduced from the data on biochemical composition and energy content, it is evident that zooplankton of the Indian Ocean contains on an average 2.7% organic carbon, rather than the widely quoted value of 6.5%. The biomass production in terms of organic...

  6. Relationship between chemical composition and magnetic susceptibility in sediment cores from Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Parthiban, G.; Banakar, V.K.; Tomer, A.; Kulkarni, M.

    Three sediment cores in a north–south transect (3 degrees N to 13 degrees S) from different sediment types of the Central Indian Ocean Basin (CIOB) are studied to understand the possible relationship between magnetic susceptibility (Chi) and Al, Fe...

  7. Volcanic ash and its enigma: A case study from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.

    An ash layer occurs between 10-35 cm depth in sediment cores from the Central Indian Ocean basin. Morphology, major, trace and rare earth element composition of glass shards from the ash layer suggest that the Youngest Toba Tuff of ~74 ka from...

  8. Early (pre–8 Ma) fault activity and temporal strain accumulation in the central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Bull, J.M.; Scrutton, R.A.

    -reflection profiles within the central Indian Ocean demonstrate that compressional activity started much earlier than previously thought, at around 15.4-13.9 Ma. From reconstructions of fault activity histories, it is shown that 12% of the total reverse fault...

  9. Distribution and origin of seamounts in the central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Das, P.; Iyer, S.D.; Kodagali, V.N.; Krishna, K.S.

    Approximately 200 seamounts of different dimensions have been identified, from multibeam bathymetry maps of the Central Indian Ocean Basin (CIOB) (9 degrees S to 16 degrees S and 72 degrees E to 80 degrees E), of which 61% form eight chains...

  10. Insects of terrestrial origin over Indian Ocean during north-east monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Pathak, S.C.; Kulshrestha, V.; Choubey, A; Parulekar, A

    Airborne insects, carried by winds were trapped over the Indian Ocean (Latitude 14 degrees N to 4 degrees S; Longitude 60 degrees-76 degrees 34 minutes E), in the course of cruise 109, ORV Sagar Kanya (January 4-February 6, 1996). A total of 3...

  11. The Indigo V Indian Ocean Expedition: a prototype for citizen microbial oceanography

    DEFF Research Database (Denmark)

    Lauro, Frederico; Senstius, Svend Jacob; Cullen, Jay

    2014-01-01

    Microbial Oceanography has long been an extremely expensive discipline, requiring ship time for sample collection and thereby economically constraining the number of samples collected. This is especially true for under-sampled water bodies such as the Indian Ocean. Specialised scientific equipmen...

  12. Size, surface texture, chemical composition and mineralogy interrelations in ferromanganese nodules of central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K; Pattan, J.N.; Jauhari, P.

    Fiftyseven ferromanganese nodules, classified into 3 size class (4,4-6 and 6-8 cm diam.), from the siliceous sediments of central Indian Ocean were analysed for transition metals and representative sample from each size class for mineralogy. Smaller...

  13. Ferromanganese nodules and their associated sediments from the Central Indian Ocean Basin: Rare earth element geochemistry

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Rao, Ch.M.; Migdisov, A.A.; Colley, S.; Higgs, N.C.; Demidenko, L.

    FerromanganeseNodulesandtheirAssociatedSedimentsfromtheCentralIndianOceanBasin:RareEarthElementGeochemistry J.N.PATTANCH.M.RAONationalInstituteofOceanography,DonaPaula Goa,IndiaA.A.MIGDISOV InstituteofGeochemistry,RussianAcademyofSciencesMoscow,Russia S.COLLEY,N.C.HIGGSSouthamptonOceanographyCentre,EmpressDockSouthampton...

  14. Mineralogy of polymetallic nodules and associated sediments from the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P

    in montmorillonite, chlorite and illite, delta MnO sub(2) is the dominant mineral phase in the nodules of the southern Central Indian Ocean Basin. These nodules have a smooth surface texture, are relatively rich in Fe and Co, and are associated with pelagic clay...

  15. Western Indian Ocean Journal of Marine Science - Vol 10, No 1 (2011)

    African Journals Online (AJOL)

    Assessing Spatio-temporal Patterns of Groundwater Salinity in Small Coral Islands in the Western Indian Ocean · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. J-L Join, O Banton, J-C Comte, J Leze, F Massin, E Nicolini, 1-12 ...

  16. CO sub(2) and N sub(2) O fluxes from the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Narvekar, P.V.; Naqvi, S.W.A.; DileepKumar, M.

    and the deep water concentrations signify quantities of N sub(2)O to be consumed within the sediments. The northern Indian Ocean as a source of CO sub(2) to the atmosphere is poorly quantified. The N sub(2)O data indicate that the vertical diffusion coefficient...

  17. Annual and seasonal mean buoyancy fluxes for the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Prasad, T.G.

    . The fluxes of heat and freshwater across the air-sea interface, and hence the surface buoyancy flux, show strong spatial and temporal variability. The Bay of Bengal and eastern equatorial Indian Ocean are characterized by a net freshwater gain due to heavy...

  18. Deep circulation in the Indian and Pacific Oceans and its implication for the dumping of low-level radioactive waste

    International Nuclear Information System (INIS)

    Harries, J.R.

    1980-06-01

    The complexity of ocean transport processes has meant that the limits for the dumping of low-activity radioactive wastes have had to be based on very simplified models of the oceans. This report discusses the models used to determine dumping limits and contrasts them with the known ocean circulation patterns. The deep circulations of the Indian and Pacific Oceans are reviewed to provide a basis for estimating the possible destinations and likely transit times for dissolved material released at the ocean floor

  19. Validation of argo data in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Muraleedharan, P.M.; Gopalakrishna, V.V.; Reddy, G.V.; Ratnakaran, L.; Revichandran, C.; Murty, V.S.N.

    Gayana (Concepción) - VALIDATION OF ARGO DATA IN THE INDIAN OCEA... 8/11/2006http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-65382004000300025&lng=... susceptible to fouling and associated drift because of the possible change... initial profiles (profiles 1 and 2). Figure-1b represents the same as that in figure-1a, but for 29 match-ups involving profile numbers 5 and above. Page 2 of 5Gayana (Concepción) - VALIDATION OF ARGO DATA IN THE INDIAN OCEA... 8/11/2006http://www...

  20. Concentrations and isotopic compositions of neodymium in the eastern Indian Ocean and Indonesian straits

    Science.gov (United States)

    Jeandel, Catherine; Thouron, Danièle; Fieux, Michèle

    1998-08-01

    Four profiles of Nd concentration and isotopic composition were determined at two stations in the eastern Indian Ocean along a north/south section between Bali and Port-Hedland and at two others in the Timor and Sumba straits. Neodymium concentrations increase with depth, between 7.2 pmol/L at the surface to 41.7 pmol/L close to the bottom. The ɛ Nd of the different water masses along the section are -7.2 ± 0.2 for the Indian Bottom Waters and -6.1 ± 0.2 for the Indian Deep Waters. The intermediate and thermocline waters are less radiogenic at st-10 than at st-20 (-5.3 ± 0.3 and -3.6 ± 0.2, respectively). In the Timor Passage and Sumba Strait, ɛ Nd of the Indonesian waters is -4.1 ± 0.2 and that of the North Indian Intermediate Waters is -2.6 ± 0.3. These distinct isotopic signals constrain the origins of the different water masses sampled in the eastern Indian Ocean. They fix the limit of the nonradiogenic Antarctic and Indian contributions to the southern part of the section whereas the northern part is influenced by radiogenic Indonesian flows. In addition, the neodymium isotopic composition suggests that in the north, deep waters are influenced by a radiogenic component originating from the Sunda Arch Slope flowing deeper than 1200 m, which was not documented previously. Mixing calculations assess the conservativity of ɛ Nd on the scale of an oceanic basin. The origin of the surprising radiogenic signal of the NIIW is discussed and could result from a remobilization of Nd sediment-hosted on the Java shelf, requiring important dissolved/particulate exchange processes. Such processes, occurring in specific areas, could play an important role in the world ocean Nd budget.

  1. Ocean tide models for satellite geodesy and Earth rotation

    Science.gov (United States)

    Dickman, Steven R.

    1991-01-01

    A theory is presented which predicts tides in turbulent, self-gravitating, and loading oceans possessing linearized bottom friction, realistic bathymetry, and continents (at coastal boundaries no-flow conditions are imposed). The theory is phrased in terms of spherical harmonics, which allows the tide equations to be reduced to linear matrix equations. This approach also allows an ocean-wide mass conservation constraint to be applied. Solutions were obtained for 32 long and short period luni-solar tidal constituents (and the pole tide), including the tidal velocities in addition to the tide height. Calibrating the intensity of bottom friction produces reasonable phase lags for all constituents; however, tidal amplitudes compare well with those from observation and other theories only for long-period constituents. In the most recent stage of grant research, traditional theory (Liouville equations) for determining the effects of angular momentum exchange on Earth's rotation were extended to encompass high-frequency excitations (such as short-period tides).

  2. Multi-satellite ocean tide modelling - the K-1 constituent

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Knudsen, Per

    1997-01-01

    All major ocean tide constituents are aliased into signals with periods less than 90 days from TOPEX/POSEIDON altimetry, except the K-1 constituent. The aliased K-1 has a period of 173 days. Consequently, it might be confounded with height variations caused by the semiannual cycle having a period......, where the presence of crossing tracks cannot separate K-1 from the semiannual signal from TOPEX/POSEIDON, the importance of including ERS-1 and GEOSAT observations was demonstrated. A comparison with 29 pelagic and coastal tide gauges in the Southern Ocean south of 50 degrees S gave 5.59 (M-2), 2.27 (S......-2) and 5.04 (K-1) cm RMS agreement for FES95.1 ocean tide model. The same comparison for the best empirical estimated constituents based on TOPEX/POSEIDON + ERS-1 + GEOSAT gave 4.32, 2.21, and 4.29 cm for M-2, S-2 and K-1, respectively....

  3. After continents divide: Comparative phylogeography of reef fishes from the Red Sea and Indian Ocean

    KAUST Repository

    Dibattista, Joseph D.; Berumen, Michael L.; Gaither, Michelle R.; Rocha, Luiz A.; Eble, Jeff A.; Choat, John Howard; Craig, Matthew T.; Skillings, Derek J.; Bowen, Brian W.

    2013-01-01

    Aim: The Red Sea is a biodiversity hotspot characterized by a unique marine fauna and high endemism. This sea began forming c. 24 million years ago with the separation of the African and Arabian plates, and has been characterized by periods of desiccation, hypersalinity and intermittent connection to the Indian Ocean. We aim to evaluate the impact of these events on the genetic architecture of the Red Sea reef fish fauna. Location: Red Sea and Western Indian Ocean. Methods: We surveyed seven reef fish species from the Red Sea and adjacent Indian Ocean using mitochondrial DNA cytochrome c oxidase subunit I and cytochrome b sequences. To assess genetic variation and evolutionary connectivity within and between these regions, we estimated haplotype diversity (h) and nucleotide diversity (π), reconstructed phylogenetic relationships among haplotypes, and estimated gene flow and time of population separation using Bayesian coalescent-based methodology. Results: Our analyses revealed a range of scenarios from shallow population structure to diagnostic differences that indicate evolutionary partitions and possible cryptic species. Conventional molecular clocks and coalescence analyses indicated time-frames for divergence between these bodies of water ranging from 830,000 years to contemporary exchange or recent range expansion. Colonization routes were bidirectional, with some species moving from the Indian Ocean to the Red Sea compared with expansion out of the Red Sea for other species. Main conclusions: We conclude that: (1) at least some Red Sea reef fauna survived multiple salinity crises; (2) endemism is higher in the Red Sea than previously reported; and (3) the Red Sea is an evolutionary incubator, occasionally contributing species to the adjacent Indian Ocean. The latter two conclusions - elevated endemism and species export - indicate a need for enhanced conservation priorities for the Red Sea. © 2013 Blackwell Publishing Ltd.

  4. After continents divide: Comparative phylogeography of reef fishes from the Red Sea and Indian Ocean

    KAUST Repository

    Dibattista, Joseph D.

    2013-01-07

    Aim: The Red Sea is a biodiversity hotspot characterized by a unique marine fauna and high endemism. This sea began forming c. 24 million years ago with the separation of the African and Arabian plates, and has been characterized by periods of desiccation, hypersalinity and intermittent connection to the Indian Ocean. We aim to evaluate the impact of these events on the genetic architecture of the Red Sea reef fish fauna. Location: Red Sea and Western Indian Ocean. Methods: We surveyed seven reef fish species from the Red Sea and adjacent Indian Ocean using mitochondrial DNA cytochrome c oxidase subunit I and cytochrome b sequences. To assess genetic variation and evolutionary connectivity within and between these regions, we estimated haplotype diversity (h) and nucleotide diversity (π), reconstructed phylogenetic relationships among haplotypes, and estimated gene flow and time of population separation using Bayesian coalescent-based methodology. Results: Our analyses revealed a range of scenarios from shallow population structure to diagnostic differences that indicate evolutionary partitions and possible cryptic species. Conventional molecular clocks and coalescence analyses indicated time-frames for divergence between these bodies of water ranging from 830,000 years to contemporary exchange or recent range expansion. Colonization routes were bidirectional, with some species moving from the Indian Ocean to the Red Sea compared with expansion out of the Red Sea for other species. Main conclusions: We conclude that: (1) at least some Red Sea reef fauna survived multiple salinity crises; (2) endemism is higher in the Red Sea than previously reported; and (3) the Red Sea is an evolutionary incubator, occasionally contributing species to the adjacent Indian Ocean. The latter two conclusions - elevated endemism and species export - indicate a need for enhanced conservation priorities for the Red Sea. © 2013 Blackwell Publishing Ltd.

  5. Role of North Indian Ocean Air-Sea Interaction in Summer Monsoon Intraseasonal Oscillation

    Science.gov (United States)

    Zhang, L.; Han, W.; Li, Y.

    2017-12-01

    Air-sea coupling processes over the North Indian Ocean associated with Indian summer monsoon intraseasonal oscillation (MISO) are analyzed. Observations show that MISO convection anomalies affect underlying sea surface temperature (SST) through changes in surface shortwave radiation (via cloud cover change) and surface latent heat flux (associated with surface wind speed change). In turn, SST anomalies determine the changing rate of MISO precipitation (dP/dt): warm (cold) SST anomalies cause increasing (decreasing) precipitation rate through increasing (decreasing) surface convergence. Air-sea interaction gives rise to a quadrature relationship between MISO precipitation and SST anomalies. A local air-sea coupling model (LACM) is established based on these observed physical processes, which is a damped oscillatory system with no external forcing. The period of LACM is proportional to the square root of mean state mixed layer depth , assuming other physical parameters remain unchanged. Hence, LACM predicts a relatively short (long) MISO period over the North Indian Ocean during the May-June monsoon developing (July-August mature) phase when is shallow (deep). This result is consistent with observed MISO statistics. An oscillatory external forcing of a typical 30-day period is added to LACM, representing intraseasonal oscillations originated from the equatorial Indian Ocean and propagate into the North Indian Ocean. The period of LACM is then determined by both the inherent period associated with local air-sea coupling and the period of external forcing. It is found that resonance occurs when , amplifying the MISO in situ. This result explains the larger MISO amplitude during the monsoon developing phase compared to the mature phase, which is associated with seasonal cycle of . LACM, however, fails to predict the observed small MISO amplitude during the September-October monsoon decaying phase, when is also shallow. This deficiency might be associated with the

  6. Ulrike Freitag: Indian Ocean, Migrants and State Formation in Hadhramaut. Reforming the Homeland. Ulrike Freitag & William Clarence-Smith : Hadhrami Traders, Scholars and Statesmen in the Indian Ocean, 1750s-1960s.

    Directory of Open Access Journals (Sweden)

    Jean Lambert

    2003-01-01

    Full Text Available Ulrike Freitag Indian Ocean, Migrants and State Formation in Hadhramaut. Reforming the Homeland Leyde / Boston, Brill, 2003 Ulrike Freitag & William Clarence-Smith (directeurs Hadhrami Traders, Scholars and Statesmen in the Indian Ocean, 1750s-1960s Leyde / New-York / Cologne, Brill, 1997 Le livre Indian Ocean, Migrants and State Formation in Hadhramaut nous présente l'histoire moderne du Hadramaout, du début du xixe siècle à la fin de la période britannique (1967, en parallèle avec...

  7. Surface temperature pattern of the Indian Ocean before summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinathan, C.K.; Rao, D.P.

    , suggests that the position of the warmer areas in the Bay of Bengal in May is an indicator of the subsequent summer rainfall over India. The statistical method adopted for the long range forcasting of the Indian summer monsoon gives very little...

  8. The Role of Indian Ocean SST Anomalies in Modulating Regional Rainfall Variability and Long-term Change

    Science.gov (United States)

    Ummenhofer, C. C.; Sen Gupta, A.; England, M. H.

    2008-12-01

    In a series of atmospheric general circulation model simulations, the potential impact of Indian Ocean sea surface temperature (SST) anomalies in modulating low- to mid-latitude precipitation around the Indian Ocean rim countries is explored. The relative importance of various characteristic tropical and subtropical Indian Ocean SST poles, both individually and in combination, to regional precipitation changes is quantified. A mechanism for the rainfall modulation is proposed, by which the SST anomalies induce changes in the thermal properties of the atmosphere, resulting in a reorganization of the large-scale atmospheric circulation across the Indian Ocean basin. Across western and southern regions of Australia, rainfall anomalies are found to be due to modulations in the meridional thickness gradient, thermal wind, and baroclinicity, leading to changes in the moisture flux onto the continent. The pattern of large-scale circulation changes over the tropical Indian Ocean and adjacent land masses is consistent with an anomalous strengthening of the Walker cell, leading to variations in precipitation of opposite sign across western and eastern regions of the basin. Links between long-term changes in Indian Ocean surface properties and regional precipitation changes in Indian Ocean rim countries are also discussed in a broader context with implications for water management and seasonal forecasting.

  9. Uncertainty in Indian Ocean Dipole response to global warming: the role of internal variability

    Science.gov (United States)

    Hui, Chang; Zheng, Xiao-Tong

    2018-01-01

    The Indian Ocean Dipole (IOD) is one of the leading modes of interannual sea surface temperature (SST) variability in the tropical Indian Ocean (TIO). The response of IOD to global warming is quite uncertain in climate model projections. In this study, the uncertainty in IOD change under global warming, especially that resulting from internal variability, is investigated based on the community earth system model large ensemble (CESM-LE). For the IOD amplitude change, the inter-member uncertainty in CESM-LE is about 50% of the intermodel uncertainty in the phase 5 of the coupled model intercomparison project (CMIP5) multimodel ensemble, indicating the important role of internal variability in IOD future projection. In CESM-LE, both the ensemble mean and spread in mean SST warming show a zonal positive IOD-like (pIOD-like) pattern in the TIO. This pIOD-like mean warming regulates ocean-atmospheric feedbacks of the interannual IOD mode, and weakens the skewness of the interannual variability. However, as the changes in oceanic and atmospheric feedbacks counteract each other, the inter-member variability in IOD amplitude change is not correlated with that of the mean state change. Instead, the ensemble spread in IOD amplitude change is correlated with that in ENSO amplitude change in CESM-LE, reflecting the close inter-basin relationship between the tropical Pacific and Indian Ocean in this model.

  10. Tracing the drift of MH370 debris throughout the Indian Ocean

    Science.gov (United States)

    Biastoch, Arne; Durgadoo, Jonathan V.; Rühs, Siren

    2017-04-01

    On 8 March 2014, a missing Boeing 777 of Malaysia Airlines (MH370) disappeared from radar screens. Since then, extensive search efforts aim to find the missing plane in the southeastern Indian Ocean. Starting with a flaperon washed up at La Réunion in July 2015, several pieces of debris were found at different shores at islands and African coasts in the southwestern Indian Ocean. Ocean currents were examined to understand the drift paths of debris throughout the Indian Ocean, and in consequence to identify the location of MH370. Here we present a series of Lagrangian analyses in which we follow particles representing virtual pieces of debris advected in an operational high-resolution ocean model. Of particular importance is the lare-scale influence of surface waves through Stokes drift. Large number of particles are analysed in statistical approaches to provide most likely starting locations. Different pieces of debris are combined to refine probability maps of their joint start positions. Forward vs. backward advection approaches are compared.

  11. Impact of including surface currents on simulation of Indian Ocean variability with the POAMA coupled model

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Mei; Wang, Guomin; Hendon, Harry H.; Alves, Oscar [Bureau of Meteorology, Centre for Australian Weather and Climate Research, Melbourne (Australia)

    2011-04-15

    Impacts on the coupled variability of the Indo-Pacific by including the effects of surface currents on surface stress are explored in four extended integrations of an experimental version of the Bureau of Meteorology's coupled seasonal forecast model POAMA. The first pair of simulations differs only in their treatment of momentum coupling: one version includes the effects of surface currents on the surface stress computation and the other does not. The version that includes the effect of surface currents has less mean-state bias in the equatorial Pacific cold tongue but produces relatively weak coupled variability in the Tropics, especially that related to the Indian Ocean dipole (IOD) and El Nino/Southern Oscillation (ENSO). The version without the effects of surface currents has greater bias in the Pacific cold tongue but stronger IOD and ENSO variability. In order to diagnose the role of changes in local coupling from changes in remote forcing by ENSO for causing changes in IOD variability, a second set of simulations is conducted where effects of surface currents are included only in the Indian Ocean and only in the Pacific Ocean. IOD variability is found to be equally reduced by inclusion of the local effects of surface currents in the Indian Ocean and by the reduction of ENSO variability as a result of including effects of surface currents in the Pacific. Some implications of these results for predictability of the IOD and its dependence on ENSO, and for ocean subsurface data assimilation are discussed. (orig.)

  12. Retrieving Temperature Anomaly in the Global Subsurface and Deeper Ocean From Satellite Observations

    Science.gov (United States)

    Su, Hua; Li, Wene; Yan, Xiao-Hai

    2018-01-01

    Retrieving the subsurface and deeper ocean (SDO) dynamic parameters from satellite observations is crucial for effectively understanding ocean interior anomalies and dynamic processes, but it is challenging to accurately estimate the subsurface thermal structure over the global scale from sea surface parameters. This study proposes a new approach based on Random Forest (RF) machine learning to retrieve subsurface temperature anomaly (STA) in the global ocean from multisource satellite observations including sea surface height anomaly (SSHA), sea surface temperature anomaly (SSTA), sea surface salinity anomaly (SSSA), and sea surface wind anomaly (SSWA) via in situ Argo data for RF training and testing. RF machine-learning approach can accurately retrieve the STA in the global ocean from satellite observations of sea surface parameters (SSHA, SSTA, SSSA, SSWA). The Argo STA data were used to validate the accuracy and reliability of the results from the RF model. The results indicated that SSHA, SSTA, SSSA, and SSWA together are useful parameters for detecting SDO thermal information and obtaining accurate STA estimations. The proposed method also outperformed support vector regression (SVR) in global STA estimation. It will be a useful technique for studying SDO thermal variability and its role in global climate system from global-scale satellite observations.

  13. Weighted West, Focused on the Indian Ocean and Cooperating across the Indo-Pacific: The Indian Navy’s New Maritime Strategy, Capabilities, and Diplomacy

    Science.gov (United States)

    2017-02-01

    including New Delhi’s official response.10 Indians also worry about China’s infrastructure investments and cooperation with countries such as...China’s increased economic and infrastructure involvement among Indian Ocean states is not new, but it has increased and expanded in recent years...and foreign nationals from Yemen . The importance of HA/DR missions for the Indian Navy has increased over the past few years—and, with the emphasis

  14. Seamounts in the Central Indian Ocean Basin: indicators of the Indian plate movement

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Khadge, N.H.

    stream_size 9 stream_content_type text/plain stream_name Proc_Indian_Acad_Sci_(EPS)_99_357.pdf.txt stream_source_info Proc_Indian_Acad_Sci_(EPS)_99_357.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  15. Cocos (Keeling) corals reveal 200 years of multidecadal modulation of southeast Indian Ocean hydrology by Indonesian throughflow

    NARCIS (Netherlands)

    Hennekam, R.; Zinke, J.; van Sebille, E.; ten Have, M.; Brummer, G.-J. A.; Reichart, G.-J.

    2018-01-01

    The only low latitude pathway of heat and salt from the Pacific Ocean to the Indian Ocean,known as Indonesian Throughflow (ITF), has been suggested to modulate Global Mean SurfaceTemperature (GMST) warming through redistribution of surface Pacific Ocean heat. ITF observations are onlyavailable since

  16. Inter-annual variability of sea surface temperature, wind speed and sea surface height anomaly over the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Muraleedharan, P.M.; Pankajakshan, T.; Sathe, P.V.

    Being land-locked at the north, the Indian Ocean and its surrounding atmosphere behave in such a way that the ocean-atmosphere interaction over this domain is different from that over the other oceans, exhibiting a peculiar dynamics. The sparse data...

  17. Sensitivity of equatorial Pacific and Indian Ocean watermasses to the position of the Indonesian Throughflow

    Science.gov (United States)

    Rodgers, Keith B.; Latif, Mojib; Legutke, Stephanie

    2000-09-01

    The sensitivity of the thermal structure of the equatorial Pacific and Indian Ocean pycnoclines to a model's representation of the Indonesian Straits connecting the two basins is investigated. Two integrations are performed using the global HOPE ocean model. The initial conditions and surface forcing for both cases are identical; the only difference between the runs is that one has an opening for the Indonesian Straits which spans the equator on the Pacific side, and the other has an opening which lies fully north of the equator. The resulting sensitivity throughout much of the upper ocean is greater than 0.5°C for both the equatorial Indian and Pacific. A realistic simulation of net Indonesian Throughflow (ITF) transport (measured in Sverdrups) is not sufficient for an adequate simulation of equatorial watermasses. The ITF must also contain a realistic admixture of northern and southern Pacific source water.

  18. Temperature profile and other data collected from XBT casts in Indian Ocean and N / S Pacific Ocean from ICEBIRD and other platforms from 02 January 1993 to 01 January 1994 (NODC Accession 9400207)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and other data were collected using XBT casts from ICEBIRD and other platforms in Indian Ocean and North / South Pacific Ocean. Data were...

  19. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from DISCOVERY in the Indian Ocean and Southern Oceans from 1994-02-19 to 1994-03-30 (NCEI Accession 0144242)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144242 includes discrete sample and profile data collected from DISCOVERY in the Indian Ocean and Southern Oceans (> 60 degrees South) from...

  20. The Indian Ocean nodule field: Geology and resource potential

    Digital Repository Service at National Institute of Oceanography (India)

    Mukhopadhyay, R.; Ghosh, A; Iyer, S.D.

    This book briefly accounts for the physiography, geology, biology, physics and chemistry of the nodule field, and discusses in detail the aspects of structure, tectonic and volcanism in the field. The role of the ocean floor sediment that hosts...

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

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  2. Structure and tectonic evolution of the northeastern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ramana, M.V.; Krishna, K.S.; Ramprasad, T.; Desa, M.; Subrahmanyam, V.; Sarma, K.V.L.N.S.

    of Pangaea and eastern Gondwanaland, and the subsequent dispersion of the continents. Inference of the mid-ocean ridge system, plateaus, banks, volcanic islands/seamounts, aseismic ridges, trenches, fracture zones, extinct spreading ridges and the hotspot...

  3. Regal phylogeography: Range-wide survey of the marine angelfish Pygoplites diacanthus reveals evolutionary partitions between the Red Sea, Indian Ocean, and Pacific Ocean

    KAUST Repository

    Coleman, Richard R.; Eble, Jeffrey A.; DiBattista, Joseph; Rocha, Luiz A.; Randall, John E.; Berumen, Michael L.; Bowen, Brian W.

    2016-01-01

    The regal angelfish (Pygoplites diacanthus; family Pomacanthidae) occupies reefs from the Red Sea to the central Pacific, with an Indian Ocean/Rea Sea color morph distinct from a Pacific Ocean morph. To assess population differentiation and evaluate the possibility of cryptic evolutionary partitions in this monotypic genus, we surveyed mtDNA cytochrome b and two nuclear introns (S7 and RAG2) in 547 individuals from 15 locations. Phylogeographic analyses revealed four mtDNA lineages (d = 0.006 – 0.015) corresponding to the Pacific Ocean, the Red Sea, and two admixed lineages in the Indian Ocean, a pattern consistent with known biogeographical barriers. Christmas Island in the eastern Indian Ocean had both Indian and Pacific lineages. Both S7 and RAG2 showed strong population-level differentiation between the Red Sea, Indian Ocean, and Pacific Ocean (ΦST = 0.066 – 0.512). The only consistent population sub-structure within these three regions was at the Society Islands (French Polynesia), where surrounding oceanographic conditions may reinforce isolation. Coalescence analyses indicate the Pacific (1.7 Ma) as the oldest extant lineage followed by the Red Sea lineage (1.4 Ma). Results from a median-joining network suggest radiations of two lineages from the Red Sea that currently occupy the Indian Ocean (0.7 – 0.9 Ma). Persistence of a Red Sea lineage through Pleistocene glacial cycles suggests a long-term refuge in this region. The affiliation of Pacific and Red Sea populations, apparent in cytochrome b and S7 (but equivocal in RAG2) raises the hypthosis that the Indian Ocean was recolonized from the Red Sea, possibly more than once. Assessing the genetic architecture of this widespread monotypic genus reveals cryptic evolutionary diversity that merits subspecific recognition.

  4. Regal phylogeography: Range-wide survey of the marine angelfish Pygoplites diacanthus reveals evolutionary partitions between the Red Sea, Indian Ocean, and Pacific Ocean

    KAUST Repository

    Coleman, Richard R.

    2016-04-08

    The regal angelfish (Pygoplites diacanthus; family Pomacanthidae) occupies reefs from the Red Sea to the central Pacific, with an Indian Ocean/Rea Sea color morph distinct from a Pacific Ocean morph. To assess population differentiation and evaluate the possibility of cryptic evolutionary partitions in this monotypic genus, we surveyed mtDNA cytochrome b and two nuclear introns (S7 and RAG2) in 547 individuals from 15 locations. Phylogeographic analyses revealed four mtDNA lineages (d = 0.006 – 0.015) corresponding to the Pacific Ocean, the Red Sea, and two admixed lineages in the Indian Ocean, a pattern consistent with known biogeographical barriers. Christmas Island in the eastern Indian Ocean had both Indian and Pacific lineages. Both S7 and RAG2 showed strong population-level differentiation between the Red Sea, Indian Ocean, and Pacific Ocean (ΦST = 0.066 – 0.512). The only consistent population sub-structure within these three regions was at the Society Islands (French Polynesia), where surrounding oceanographic conditions may reinforce isolation. Coalescence analyses indicate the Pacific (1.7 Ma) as the oldest extant lineage followed by the Red Sea lineage (1.4 Ma). Results from a median-joining network suggest radiations of two lineages from the Red Sea that currently occupy the Indian Ocean (0.7 – 0.9 Ma). Persistence of a Red Sea lineage through Pleistocene glacial cycles suggests a long-term refuge in this region. The affiliation of Pacific and Red Sea populations, apparent in cytochrome b and S7 (but equivocal in RAG2) raises the hypthosis that the Indian Ocean was recolonized from the Red Sea, possibly more than once. Assessing the genetic architecture of this widespread monotypic genus reveals cryptic evolutionary diversity that merits subspecific recognition.

  5. Regional State of the Coast Report - Western Indian Ocean

    CSIR Research Space (South Africa)

    Bosire, J

    2015-12-01

    Full Text Available protected area in Africa, covering more than 4020 square miles. The region continues to explore new and innovative options for managing oceans and coasts. We also recognise the transboundary nature of shared ocean resources, and our governments have... to list, we would like to express sincere appreciations to the: All Contracting Parties to the Nairobi Convention for supporting the focal points and the Governments of Kenya and Mozambique for graciously hosting and supporting capacity building...

  6. Combining Satellite and in Situ Data with Models to Support Climate Data Records in Ocean Biology

    Science.gov (United States)

    Gregg, Watson

    2011-01-01

    The satellite ocean color data record spans multiple decades and, like most long-term satellite observations of the Earth, comes from many sensors. Unfortunately, global and regional chlorophyll estimates from the overlapping missions show substantial biases, limiting their use in combination to construct consistent data records. SeaWiFS and MODIS-Aqua differed by 13% globally in overlapping time segments, 2003-2007. For perspective, the maximum change in annual means over the entire Sea WiFS mission era was about 3%, and this included an El NinoLa Nina transition. These discrepancies lead to different estimates of trends depending upon whether one uses SeaWiFS alone for the 1998-2007 (no significant change), or whether MODIS is substituted for the 2003-2007 period (18% decline, P less than 0.05). Understanding the effects of climate change on the global oceans is difficult if different satellite data sets cannot be brought into conformity. The differences arise from two causes: 1) different sensors see chlorophyll differently, and 2) different sensors see different chlorophyll. In the first case, differences in sensor band locations, bandwidths, sensitivity, and time of observation lead to different estimates of chlorophyll even from the same location and day. In the second, differences in orbit and sensitivities to aerosols lead to sampling differences. A new approach to ocean color using in situ data from the public archives forces different satellite data to agree to within interannual variability. The global difference between Sea WiFS and MODIS is 0.6% for 2003-2007 using this approach. It also produces a trend using the combination of SeaWiFS and MODIS that agrees with SeaWiFS alone for 1998-2007. This is a major step to reducing errors produced by the first cause, sensor-related discrepancies. For differences that arise from sampling, data assimilation is applied. The underlying geographically complete fields derived from a free-running model is unaffected

  7. New insights into the geodiversity of the southeast Indian Ocean seafloor revealed by Malaysia Airlines flight MH370 search data

    Science.gov (United States)

    Picard, K.; Brooke, B. B.; Harris, P. T.; Siwabessy, J. P. W.; Coffin, M. F.; Tran, M.; Spinoccia, M.; Weales, J.; Macmillan-Lawler, M.; Sullivan, J.

    2017-12-01

    A large multibeam echo sounder (MBES) dataset (710, 000 km2, inclusive of transit data) was acquired in the SE Indian Ocean to assist the search for Malaysia Airlines Flight 370 (MH370). Here, we present the results of a geomorphic analysis of this new data and compare with the Global Seafloor Geomorphic Features Map (GSFM) that is based on coarser resolution satellite-derived bathymetry data. The analyses show that abyssal plains and basins are significantly more rugged than their representation in the GSFM, with a 20% increase in the extent of hills and mountains. The new model also reveals four times more seamounts than presented in the GSFM, suggesting a greater number of these features than previously estimated for the broader region and indeed globally. This is important considering the potential ecological significance of these high-relief structures. Analyses of the new data also enabled knolls, fans, valleys, canyons, troughs and holes to be identified, doubling the number of discrete features mapped and revealing the true geodiversity of the deep ocean in this area. This high-resolution mapping of the seafloor also provides new insights into the geological evolution of the region, both in terms of structural, tectonic, and sedimentary processes. For example, sub-parallel ridges extend over approximately 20% of the area mapped and their form and alignment provide valuable insight into Southeast Indian Ridge seafloor spreading processes. Rifting is recorded along the Broken Ridge - Diamantina Escarpment, with rift blocks and well-bedded sedimentary bedrock exposures discernible down to 2,400 m water depth. Ocean floor sedimentary processes are represented in sediment mass transport features, especially along and north of Broken Ridge, and pockmarks (the finest-scale features mapped) south of Diamantina Trench. The new MBES data highlight the complexity of the search area and serve to demonstrate how little we know about the 85-90% of the ocean floor that

  8. Magma Supply of Southwest Indian Ocean: Implication from Crustal Thickness Anomalies

    Science.gov (United States)

    Chiheng, L.; Jianghai, L.; Huatian, Z.; Qingkai, F.

    2017-12-01

    The Southwest Indian Ridge (SWIR) is one of the world's slowest spreading ridges with a full spreading rate of 14mm a-1, belonging to ultraslow spreading ridge, which are a novel class of spreading centers symbolized by non-uniform magma supply and crustal accretion. Therefore, the crustal thickness of Southwest Indian Ocean is a way to explore the magmatic and tectonic process of SWIR and the hotspots around it. Our paper uses Residual Mantle Bouguer Anomaly processed with the latest global public data to invert the relative crustal thickness and correct it according to seismic achievements. Gravity-derived crustal thickness model reveals a huge range of crustal thickness in Southwest Indian Ocean from 0.04km to 24km, 7.5km of average crustal thickness, and 3.5km of standard deviation. In addition, statistics data of crustal thickness reveal the frequency has a bimodal mixed skewed distribution, which indicates the crustal accretion by ridge and ridge-plume interaction. Base on the crustal thickness model, we divide three types of crustal thickness in Southwest Indian Ocean. About 20.31% of oceanic crust is 9.8km thick as thick crust. Furthermore, Prominent thin crust anomalies are associated with the trend of most transform faults, but thick crust anomalies presents to northeast of Andrew Bain transform fault. Cold and depleted mantle are also the key factors to form the thin crust. The thick crust anomalies are constrained by hotspots, which provide abundant heat to the mantle beneath mid-ocean ridge or ocean basin. Finally, we roughly delineate the range of ridge-plume interaction and transform fault effect.

  9. Use of satellite ocean color observations to refine understanding of global geochemical cycles

    Science.gov (United States)

    Walsh, J. J.; Dieterle, D. A.

    1985-01-01

    In October 1978, the first satellite-borne color sensor, the Coastal Zone Color Scanner (CZCS), was launched aboard Nimbus-7 with four visible and two infrared bands, permitting a sensitivity about 60 times that of the Landsat-1 multispectral scanner. The CZCS radiance data can be utilized to estimate ocean chlorophyll concentrations by detecting shifts in sea color, particularly in oceanic waters. The obtained data can be used in studies regarding problems of overfishing, and, in addition, in investigations concerning the consequences of man's accelerated extraction of nitrogen from the atmosphere and addition of carbon to the atmosphere. The satellite data base is considered along with a simulation analysis, and ships providing ground-truth chlorophyll measurements in the ocean.

  10. Cloud amount/frequency, NITRATE and other data from unknown platforms in the Indian Ocean from 1992-05-23 to 1993-02-04 (NODC Accession 9400144)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ten data files containing 2,738 data records were submitted by Martien Baars to NODC/Ocean Climate Laboratory from the Netherlands Indian Ocean Programme. These...

  11. 3D Gravimetric Modeling of the Spreading System North and Southeast of the Rodriguez Triple Junction (Indian Ocean)

    Science.gov (United States)

    Heyde, I.; Girolami, C.; Barckhausen, U.; Freitag, R.

    2017-12-01

    Hydrothermal vent fields along mid-ocean ridges can be metal-rich and thus of great importance for the industries in the future. By order of the German Federal Ministry of Economics and in coordination with the International Seabed Authority (ISA), BGR explores potential areas of the active spreading system in the Indian Ocean. A main goal is the identification of inactive seafloor massive sulfides (SMS) with the aid of modern exploration techniques. Important contributions could be expected from bathymetric, magnetic, and gravity datasets, which can be acquired simultaneously time from the sea surface within relatively short ship time. The area of interest is located between 21°S and 28°S and includes the southern Central Indian Ridge (CIR) and the northern Southeast Indian Ridge (SEIR). In this study we analyzed the marine gravity and bathymetric data acquired during six research cruises. The profiles running perpendicular to the ridge axis have a mean length of 60 km. Magnetic studies reveal that the parts of the ridges covered are geologically very young with the oldest crust dating back to about 1 Ma. To extend the area outside the ridges, the shipboard data were complemented with data derived from satellite radar altimeter measurements. We analyzed the gravity anomalies along sections which cross particular geologic features (uplifted areas, accommodation zones, hydrothermal fields, and areas with hints for extensional processes e.g. oceanic core complexes) to establish a correlation between the gravity anomalies and the surface geology. Subsequently, for both ridge segments 3D density models were developed. We started with simple horizontally layered models, which, however, do not explain the measured anomalies satisfyingly. The density values of the crust and the upper mantle in the ridge areas had to be reduced. Finally, the models show the lateral heterogeneity and the variations in the thickness of the oceanic crust. There are areas characterized by

  12. Accuracy assessment of satellite Ocean colour products in coastal waters.

    Science.gov (United States)

    Tilstone, G.; Lotliker, A.; Groom, S.

    2012-04-01

    The use of Ocean Colour Remote Sensing to monitor phytoplankton blooms in coastal waters is hampered by the absorption and scattering from substances in the water that vary independently of phytoplankton. In this paper we compare different ocean colour algorithms available for SeaWiFS, MODIS and MERIS with in situ observations of Remote Sensing Reflectance, Chlorophyll-a (Chla), Total Suspended Material and Coloured Dissolved Organic Material in coastal waters of the Arabian Sea, Bay of Bengal, North Sea and Western English Channel, which have contrasting inherent optical properties. We demonstrate a clustering method on specific-Inherent Optical Properties (sIOP) that gives accurate water quality products from MERIS data (HYDROPT) and also test the recently developed ESA CoastColour MERIS products. We found that for coastal waters of the Bay of Bengal, OC5 gave the most accurate Chla, for the Arabian Sea GSM and OC3M Chla were more accurate and for the North Sea and Western English Channel, MERIS HYDROPT were more accurate than standard algorithms. The reasons for these differences will be discussed. A Chla time series from 2002-2011 will be presented to illustrate differences in algorithms between coastal regions and inter- and intra-annual variability in phytoplankton blooms

  13. Mapping Global Ocean Surface Albedo from Satellite Observations: Models, Algorithms, and Datasets

    Science.gov (United States)

    Li, X.; Fan, X.; Yan, H.; Li, A.; Wang, M.; Qu, Y.

    2018-04-01

    Ocean surface albedo (OSA) is one of the important parameters in surface radiation budget (SRB). It is usually considered as a controlling factor of the heat exchange among the atmosphere and ocean. The temporal and spatial dynamics of OSA determine the energy absorption of upper level ocean water, and have influences on the oceanic currents, atmospheric circulations, and transportation of material and energy of hydrosphere. Therefore, various parameterizations and models have been developed for describing the dynamics of OSA. However, it has been demonstrated that the currently available OSA datasets cannot full fill the requirement of global climate change studies. In this study, we present a literature review on mapping global OSA from satellite observations. The models (parameterizations, the coupled ocean-atmosphere radiative transfer (COART), and the three component ocean water albedo (TCOWA)), algorithms (the estimation method based on reanalysis data, and the direct-estimation algorithm), and datasets (the cloud, albedo and radiation (CLARA) surface albedo product, dataset derived by the TCOWA model, and the global land surface satellite (GLASS) phase-2 surface broadband albedo product) of OSA have been discussed, separately.

  14. Ferromanganese oxides from Mid-Indian ridge, seamounts and abyssal plains from the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.; Pattan, J.N.

    .47%) in the seamount crusts. The ferromanganese oxides from the Mid-Indian Ridge, seamount crusts and abyssal nodules appear to be of hydrothermal, hydrogenous and early-diagenetic in origin respectively...

  15. Nutrient characteristics of the water masses and their seasonal variability in the eastern equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.; Shetye, S.; Maya, M.V.; Mangala, K.R.; PrasannaKumar, S.

    . (Position of Fig 1.) 3. Results and Discussion 3.1. Water masses in the area of observation You and Tomczak (1993) has reviewed the water masses in the Indian Ocean identified by the earlier workers ( Sverdrup et al. 1942; Mamalev, 1975; and Shcherbinin... at 200 m at 5° S in the meridional region of our observations and flows down to 800 m to the north and termed as Indian central water (ICW) (You and Tomczak, 1993). (position of Fig.2) 3.2. Seasonal variability of water masses The seasonal...

  16. Indian Ocean radiocarbon: Data from the INDIGO 1, 2, and 3 cruises

    International Nuclear Information System (INIS)

    Sepanski, R.J.

    1991-01-01

    This document presents 14 C activities (expressed in the internationally adopted Δ 14 C scale) from water samples taken at various locations and depths in the Indian and Southern oceans through the Indien Gaz Ocean (INDIGO) project. These data were collected as part of the INDIGO 1, INDIGO 2, and INDIGO 3 cruises, which took place during the years 1985, 1986, and 1987, respectively. These data have been used to estimate the penetration of anthropogenic CO 2 in the Indian and Southern oceans. The document also presents supporting data for potential temperature, salinity, density (sigma-theta), δ 13 C, and total CO 2 . All radiocarbon measurements have been examined statistically for quality of sample counts and stability of counting efficiency and background. In addition, all data have been reviewed by the Carbon Dioxide Information Analysis Center and assessed for gross accuracy and consistency (absence of obvious outliers and other anomalous values). These data are available free of charge as a numeric data package (NDP) from the Carbon Dioxide Information Analysis Center. The NDP consists of this document and a magnetic tape containing machine-readable files. This document provides sample listing of the Indian Ocean radiocarbon data as they appear on the magnetic tape, as well as a complete listing of these data in tabular form. This document also offers retrieval program listings, furnishes information on sampling methods and data selection, defines limitations and restrictions of the data, and provides reprints of pertinent literature. 13 refs., 4 tabs

  17. A new dipole index of the salinity anomalies of the tropical Indian Ocean.

    Science.gov (United States)

    Li, Junde; Liang, Chujin; Tang, Youmin; Dong, Changming; Chen, Dake; Liu, Xiaohui; Jin, Weifang

    2016-04-07

    With the increased interest in studying the sea surface salinity anomaly (SSSA) of the tropical Indian Ocean during the Indian Ocean Dipole (IOD), an index describing the dipole variability of the SSSA has been pursued recently. In this study, we first use a regional ocean model with a high spatial resolution to produce a high-quality salinity simulation during the period from 1982 to 2014, from which the SSSA dipole structure is identified for boreal autumn. On this basis, by further analysing the observed data, we define a dipole index of the SSSA between the central equatorial Indian Ocean (CEIO: 70°E-90°E, 5°S-5°N) and the region off the Sumatra-Java coast (SJC: 100°E-110°E, 13°S-3°S). Compared with previous SSSA dipole indices, this index has advantages in detecting the dipole signals and in characterizing their relationship to the sea surface temperature anomaly (SSTA) dipole variability. Finally, the mechanism of the SSSA dipole is investigated by dynamical diagnosis. It is found that anomalous zonal advection dominates the SSSA in the CEIO region, whereas the SSSA in the SJC region are mainly influenced by the anomalous surface freshwater flux. This SSSA dipole provides a positive feedback to the formation of the IOD events.

  18. Seasonal cycle of cross-equatorial flow in the central Indian Ocean

    Science.gov (United States)

    Wang, Yi; McPhaden, Michael J.

    2017-05-01

    This study investigates the seasonal cycle of meridional currents in the upper layers of central equatorial Indian Ocean using acoustic Doppler current profiler (ADCP) and other data over the period 2004-2013. The ADCP data set collected along 80.5°E is the most comprehensive collection of direct velocity measurements in the central Indian Ocean to date, providing new insights into the meridional circulation in this region. We find that mean volume transport is southward across the equator in the central Indian Ocean in approximate Sverdrup balance with the wind stress curl. In addition, mean westerly wind stress near the equator drives convergent Ekman flow in the surface layer and subsurface divergent geostrophic flow in the thermocline at 50-150 m depths. In response to a mean northward component of the surface wind stress, the maximum surface layer convergence is shifted off the equator to between 0.5° and 1°N. Evidence is also presented for the existence of a shallow equatorial roll consisting of a northward wind-driven surface drift overlaying the southward directed subsurface Sverdrup transport. Seasonal variations are characterized by cross-equatorial transports flowing from the summer to the winter hemisphere in quasi-steady Sverdrup balance with the wind stress curl. In addition, semiannually varying westerly monsoon transition winds lead to semiannual enhancements of surface layer Ekman convergence and geostrophic divergence in the thermocline. These results quantify expectations from ocean circulation theories for equatorial Indian Ocean meridional circulation patterns with a high degree of confidence given the length of the data records.

  19. Assessing the internal consistency of the CARINA database in the Indian sector of the Southern Ocean

    Directory of Open Access Journals (Sweden)

    C. Lo Monaco

    2010-02-01

    Full Text Available Carbon and carbon-relevant hydrographic and hydrochemical ancillary data from previously not publicly available cruises were retrieved and recently merged to a new data base, CARINA (CARbon IN the Atlantic. The initial North Atlantic project, an international effort for ocean carbon synthesis, was extended to include the Arctic Mediterranean Seas (Arctic Ocean and Nordic Seas and all three sectors of the Southern Ocean. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean. The present work focuses on data collected in the Indian sector (20° S–70° S; 30° E–150° E. The Southern Indian Ocean dataset covers the period 1992–2004 and includes seasonal repeated observations. Parameters including salinity, dissolved inorganic carbon (TCO2, total alkalinity (TA, oxygen, nitrate, phosphate and silicate were examined for cruise-to-cruise and overall consistency. In addition, data from an existing, quality controlled data base (GLODAP were introduced in the CARINA analysis to improve data coverage in the Southern Ocean. A global inversion was performed to synthesize the information deduced from objective comparisons of deep measurements (>1500 m at nearby stations (generally <220 km. The corrections suggested by the inversion were allowed to vary within a fixed envelope, thus accounting for ocean interior variability. The adjustments applied to CARINA data and those recommended for GLODAP data, in order to obtain a consistent merged dataset, are presented and discussed. The final outcome of this effort is a new quality controlled data base for TCO2 and other properties of the carbon system that can now be used to investigate the natural variability or stability of ocean chemistry and the accumulation of anthropogenic carbon. This data product also offers an important new synthesis of seasonal to decadal observations to validate ocean biogeochemical models in a region where available historical data were very

  20. Simulation of space-borne tsunami detection using GNSS-Reflectometry applied to tsunamis in the Indian Ocean

    Directory of Open Access Journals (Sweden)

    R. Stosius

    2010-06-01

    Full Text Available Within the German-Indonesian Tsunami Early Warning System project GITEWS (Rudloff et al., 2009, a feasibility study on a future tsunami detection system from space has been carried out. The Global Navigation Satellite System Reflectometry (GNSS-R is an innovative way of using reflected GNSS signals for remote sensing, e.g. sea surface altimetry. In contrast to conventional satellite radar altimetry, multiple height measurements within a wide field of view can be made simultaneously. With a dedicated Low Earth Orbit (LEO constellation of satellites equipped with GNSS-R, densely spaced sea surface height measurements could be established to detect tsunamis. This simulation study compares the Walker and the meshed comb constellation with respect to their global reflection point distribution. The detection performance of various LEO constellation scenarios with GPS, GLONASS and Galileo as signal sources is investigated. The study concentrates on the detection performance for six historic tsunami events in the Indian Ocean generated by earthquakes of different magnitudes, as well as on different constellation types and orbit parameters. The GNSS-R carrier phase is compared with the PARIS or code altimetry approach. The study shows that Walker constellations have a much better reflection point distribution compared to the meshed comb constellation. Considering simulation assumptions and assuming technical feasibility it can be demonstrated that strong tsunamis with magnitudes (M ≥8.5 can be detected with certainty from any orbit altitude within 15–25 min by a 48/8 or 81/9 Walker constellation if tsunami waves of 20 cm or higher can be detected by space-borne GNSS-R. The carrier phase approach outperforms the PARIS altimetry approach especially at low orbit altitudes and for a low number of LEO satellites.

  1. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from AURORA AUSTRALIS in the Indian Ocean, South Pacific Ocean and Southern Oceans from 2011-01-04 to 2011-02-06 (NCEI Accession 0143947)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143947 includes discrete sample and profile data collected from AURORA AUSTRALIS in the Indian Ocean, South Pacific Ocean and Southern Oceans (>...

  2. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from MIRAI in the Indian Ocean, South Pacific Ocean and Southern Oceans from 2012-11-28 to 2013-01-04 (NCEI Accession 0143950)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143950 includes discrete sample and profile data collected from MIRAI in the Indian Ocean, South Pacific Ocean and Southern Oceans (> 60 degrees...

  3. Dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from POLARSTERN in the Indian Ocean, South Atlantic Ocean and Southern Oceans from 1996-03-17 to 1996-05-20 (NODC Accession 0116640)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0116640 includes discrete sample and profile data collected from POLARSTERN in the Indian Ocean, South Atlantic Ocean and Southern Oceans (> 60...

  4. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from JAMES CLARK ROSS in the Indian Ocean, South Atlantic Ocean and Southern Oceans from 2008-12-26 to 2009-01-30 (NODC Accession 0110254)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0110254 includes discrete sample and profile data collected from JAMES CLARK ROSS in the Indian Ocean, South Atlantic Ocean and Southern Oceans (>...

  5. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, PAR Sensor and other instruments from AURORA AUSTRALIS in the Indian Ocean, South Pacific Ocean and Southern Oceans from 2007-12-16 to 2008-01-27 (NCEI Accession 0143932)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143932 includes discrete sample and profile data collected from AURORA AUSTRALIS in the Indian Ocean, South Pacific Ocean and Southern Oceans (>...

  6. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from DISCOVERY in the Indian Ocean, South Atlantic Ocean and Southern Oceans from 1993-02-06 to 1993-03-18 (NCEI Accession 0143944)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0143944 includes discrete sample and profile data collected from DISCOVERY in the Indian Ocean, South Atlantic Ocean and Southern Oceans (> 60...

  7. Assessment of Satellite Ocean Colour Radiometry and Derived Geophysical Products. Chapter 6.1

    Science.gov (United States)

    Melin, Frederic; Franz, Bryan A.

    2014-01-01

    Standardization of methods to assess and assign quality metrics to satellite ocean color radiometry and derived geophysical products has become paramount with the inclusion of the marine reflectance and chlorophyll-a concentration (Chla) as essential climate variables (ECV; [1]) and the recognition that optical remote sensing of the oceans can only contribute to climate research if and when a continuous succession of satellite missions can be shown to collectively provide a consistent, long-term record with known uncertainties. In 20 years, the community has made significant advancements toward that objective, but providing a complete uncertainty budget for all products and for all conditions remains a daunting task. In the retrieval of marine water-leaving radiance from observed top-of-atmosphere radiance, the sources of uncertainties include those associated with propagation of sensor noise and radiometric calibration and characterization errors, as well as a multitude of uncertainties associated with the modeling and removal of effects from the atmosphere and sea surface. This chapter describes some common approaches used to assess quality and consistency of ocean color satellite products and reviews the current status of uncertainty quantification in the field. Its focus is on the primary ocean color product, the spectrum of marine reflectance Rrs, but uncertainties in some derived products such as the Chla or inherent optical properties (IOPs) will also be considered.

  8. From silk to satellite: Half a century of ocean colour anomalies in the Northeast Atlantic

    KAUST Repository

    Raitsos, Dionysios E.; Pradhan, Yaswant; Lavender, Sam; Hoteit, Ibrahim; McQuatters-Gollop, Abigail L.; Reid, Philip Chris; Richardson, Anthony J.

    2014-01-01

    Changes in phytoplankton dynamics influence marine biogeochemical cycles, climate processes, and food webs, with substantial social and economic consequences. Large-scale estimation of phytoplankton biomass was possible via ocean colour measurements from two remote sensing satellites - the Coastal Zone Colour Scanner (CZCS, 1979-1986) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, 1998-2010). Due to the large gap between the two satellite eras and differences in sensor characteristics, comparison of the absolute values retrieved from the two instruments remains challenging. Using a unique in situ ocean colour dataset that spans more than half a century, the two satellite-derived chlorophyll-a (Chl-a) eras are linked to assess concurrent changes in phytoplankton variability and bloom timing over the Northeast Atlantic Ocean and North Sea. Results from this unique re-analysis reflect a clear increasing pattern of Chl-a, a merging of the two seasonal phytoplankton blooms producing a longer growing season and higher seasonal biomass, since the mid-1980s. The broader climate plays a key role in Chl-a variability as the ocean colour anomalies parallel the oscillations of the Northern Hemisphere Temperature (NHT) since 1948. © 2013 John Wiley & Sons Ltd.

  9. Extracting Ocean-Generated Tidal Magnetic Signals from Swarm Data Through Satellite Gradiometry

    Science.gov (United States)

    Sabaka, Terence J.; Tyler, Robert H.; Olsen, Nils

    2016-01-01

    Ocean-generated magnetic field models of the Principal Lunar, M2, and the Larger Lunar elliptic, N2, semidiurnal tidal constituents were estimated through a "Comprehensive Inversion" of the first 20.5 months of magnetic measurements from European Space Agency's (ESA) Swarm satellite constellation mission. While the constellation provides important north-south along-track gradiometry information, it is the unique low-spacecraft pair that allows for east-west cross-track gradiometry. This latter type is crucial in delivering an M2 estimate of similar quality with that derived from over 10 years of CHAMP satellite data but over a shorter interval, at higher altitude, and during more magnetically disturbed conditions. Recovered N2 contains nonoceanic signal but is highly correlated with theoretical models in regions of maximum oceanic amplitude. Thus, satellite magnetic gradiometry may eventually enable the monitoring of ocean electrodynamic properties at temporal resolutions of 1 to 2 years, which may have important implications for the inference of ocean temperature and salinity.

  10. From silk to satellite: Half a century of ocean colour anomalies in the Northeast Atlantic

    KAUST Repository

    Raitsos, Dionysios E.

    2014-04-23

    Changes in phytoplankton dynamics influence marine biogeochemical cycles, climate processes, and food webs, with substantial social and economic consequences. Large-scale estimation of phytoplankton biomass was possible via ocean colour measurements from two remote sensing satellites - the Coastal Zone Colour Scanner (CZCS, 1979-1986) and the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, 1998-2010). Due to the large gap between the two satellite eras and differences in sensor characteristics, comparison of the absolute values retrieved from the two instruments remains challenging. Using a unique in situ ocean colour dataset that spans more than half a century, the two satellite-derived chlorophyll-a (Chl-a) eras are linked to assess concurrent changes in phytoplankton variability and bloom timing over the Northeast Atlantic Ocean and North Sea. Results from this unique re-analysis reflect a clear increasing pattern of Chl-a, a merging of the two seasonal phytoplankton blooms producing a longer growing season and higher seasonal biomass, since the mid-1980s. The broader climate plays a key role in Chl-a variability as the ocean colour anomalies parallel the oscillations of the Northern Hemisphere Temperature (NHT) since 1948. © 2013 John Wiley & Sons Ltd.

  11. How can present and future satellite missions support scientific studies that address ocean acidification?

    Science.gov (United States)

    Salisbury, Joseph; Vandemark, Douglas; Jonsson, Bror; Balch, William; Chakraborty, Sumit; Lohrenz, Steven; Chapron, Bertrand; Hales, Burke; Mannino, Antonio; Mathis, Jeremy T.; Reul, Nicolas; Signorini, Sergio; Wanninkhof, Rik; Yates, Kimberly K.

    2016-01-01

    Space-based observations offer unique capabilities for studying spatial and temporal dynamics of the upper ocean inorganic carbon cycle and, in turn, supporting research tied to ocean acidification (OA). Satellite sensors measuring sea surface temperature, color, salinity, wind, waves, currents, and sea level enable a fuller understanding of a range of physical, chemical, and biological phenomena that drive regional OA dynamics as well as the potentially varied impacts of carbon cycle change on a broad range of ecosystems. Here, we update and expand on previous work that addresses the benefits of space-based assets for OA and carbonate system studies. Carbonate chemistry and the key processes controlling surface ocean OA variability are reviewed. Synthesis of present satellite data streams and their utility in this arena are discussed, as are opportunities on the horizon for using new satellite sensors with increased spectral, temporal, and/or spatial resolution. We outline applications that include the ability to track the biochemically dynamic nature of water masses, to map coral reefs at higher resolution, to discern functional phytoplankton groups and their relationships to acid perturbations, and to track processes that contribute to acid variation near the land-ocean interface.

  12. First satellite tracks of neonate sea turtles redefine the ‘lost years’ oceanic niche

    Science.gov (United States)

    Mansfield, Katherine L.; Wyneken, Jeanette; Porter, Warren P.; Luo, Jiangang

    2014-01-01

    Few at-sea behavioural data exist for oceanic-stage neonate sea turtles, a life-stage commonly referred to as the sea turtle ‘lost years’. Historically, the long-term tracking of small, fast-growing organisms in the open ocean was logistically or technologically impossible. Here, we provide the first long-term satellite tracks of neonate sea turtles. Loggerheads (Caretta caretta) were remotely tracked in the Atlantic Ocean using small solar-powered satellite transmitters. We show that oceanic-stage turtles (i) rarely travel in Continental Shelf waters, (ii) frequently depart the currents associated with the North Atlantic Subtropical Gyre, (iii) travel quickly when in Gyre currents, and (iv) select sea surface habitats that are likely to provide a thermal benefit or refuge to young sea turtles, supporting growth, foraging and survival. Our satellite tracks help define Atlantic loggerhead nursery grounds and early loggerhead habitat use, allowing us to re-examine sea turtle ‘lost years’ paradigms. PMID:24598420

  13. Archaeological sites on the Indian Ocean Rim - A growing database

    Digital Repository Service at National Institute of Oceanography (India)

    Gaur, A.S.

    Identification: The Hinayana Buddhist caves at Kudo overlook the inner shore of the Janjlra Creek (Fig. 3]. These caves carry Brahmi 'n",,;pl;on, allhe emly centune, CE men,;on;n 9 A , • JOORNIIl. OF INO'''''' OCEAN ARCHAEOlOG' No.4, 2007 1103~ ...

  14. Sea surface salinity variability in the tropical Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Subrahmanyam, B; Murty, V.S.N.; Heffner, D.M.

    (EIO: 5 degrees S- 5 degrees N, 90 degrees-95 degrees E) and Southeastern Arabian Sea (SEAS: 5 degrees-9 degrees N, 72 degrees-76 degrees E) and to compare with the HYbrid Coordinate Ocean Model (HYCOM) simulated SSS for the period from January 2002...

  15. Aluminium in the northwestern Indian Ocean (Arabian Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    Upadhyay, S.; SenGupta, R.

    37-52 nM) A pronounced maximum in the surface mixed layer suggests the dissolution of Al from atmospherically derived particles to be the sourec of excess Al in the offshore waters of the Arabian Sea, compared to other oceanic regions...

  16. The monsoon currents in the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Shankar, D.; Vinayachandran, P.N.; Unnikrishnan, A.S.

    . Journal of Geo- physical Research 97, 20169?20178. Pond, S., Pickard, G. L., 1983. Introductory dynamical oceanography, 2nd Edition. Pergamon Press, Oxford. Potemra, J. T., Luther, M. E., O'Brien, J. J., 1991. The seasonal circulation of the upper ocean...

  17. Monsoon regime in the Indian Ocean and zooplankton variability

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.

    and the estuaries in order to show how the monsoon exerts its influence on zooplankton from different types of environment. In the open ocean, the semi-annually reversing system of currents exert profound influence on the shifting of zooplankton populations and its...

  18. Satellite Observations of Imprint of Oceanic Current on Wind Stress by Air-Sea Coupling.

    Science.gov (United States)

    Renault, Lionel; McWilliams, James C; Masson, Sebastien

    2017-12-18

    Mesoscale eddies are present everywhere in the ocean and partly determine the mean state of the circulation and ecosystem. The current feedback on the surface wind stress modulates the air-sea transfer of momentum by providing a sink of mesoscale eddy energy as an atmospheric source. Using nine years of satellite measurements of surface stress and geostrophic currents over the global ocean, we confirm that the current-induced surface stress curl is linearly related to the current vorticity. The resulting coupling coefficient between current and surface stress (s τ [N s m -3 ]) is heterogeneous and can be roughly expressed as a linear function of the mean surface wind. s τ expresses the sink of eddy energy induced by the current feedback. This has important implications for air-sea interaction and implies that oceanic mean and mesoscale circulations and their effects on surface-layer ventilation and carbon uptake are better represented in oceanic models that include this feedback.

  19. Calibration Uncertainty in Ocean Color Satellite Sensors and Trends in Long-term Environmental Records

    Science.gov (United States)

    Turpie, Kevin R.; Eplee, Robert E., Jr.; Franz, Bryan A.; Del Castillo, Carlos

    2014-01-01

    Launched in late 2011, the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership (NPP) spacecraft is being evaluated by NASA to determine whether this sensor can continue the ocean color data record established through the Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) and the MODerate resolution Imaging Spectroradiometer (MODIS). To this end, Goddard Space Flight Center generated evaluation ocean color data products using calibration techniques and algorithms established by NASA during the SeaWiFS and MODIS missions. The calibration trending was subjected to some initial sensitivity and uncertainty analyses. Here we present an introductory assessment of how the NASA-produced time series of ocean color is influenced by uncertainty in trending instrument response over time. The results help quantify the uncertainty in measuring regional and global biospheric trends in the ocean using satellite remote sensing, which better define the roles of such records in climate research.

  20. Satellite passive microwave rain measurement techniques for land and ocean

    Science.gov (United States)

    Spencer, R. W.

    1985-01-01

    Multiseasonal rainfall was found to be measurable over land with satellite passive microwave data, based upon comparisons between Nimbus 7 Scanning Multichannel Microwave Radiometer (SMME) brightness temperatures (T sub B) and operational WSR-57 radar rain rates. All of the SMMR channels (bipolarized 37, 21, 18, 10.7, and 6.6. GHz T sub B) were compared to radar reflectivities for 25 SMMR passes and 234 radar scans over the U.S. during the spring, summer, and fall of 1979. It was found that the radar rain rates were closely related to the difference between 37 and 21 GHz T sub B. This result is due to the volume scattering effects of precipitation which cause emissivity decreases with frequency, as opposed to emissive surfaces (e.g., water) whose emissivities increase with frequency. Two frequencies also act to reduce the effects of thermometric temperature variations on T sub B to a miminum. During summer and fall, multiple correlation coefficients of 0.80 and 0.75 were obtained. These approach the limit of correlation that can be expected to exist between two very different data sources, especially in light of the errors attributable to manual digitization of PPI photographs of variable quality from various operational weather radar not calibrated for research purposes. During the spring, a significantly lower (0.63) correlation was found. This poorer performance was traced to cases of wet, unvegetated soil being sensed at the lower frequencies through light rain, partly negating the rain scattering signal.

  1. Detection of anthropogenic climate change in satellite records of ocean chlorophyll and productivity

    Directory of Open Access Journals (Sweden)

    S. A. Henson

    2010-02-01

    Full Text Available Global climate change is predicted to alter the ocean's biological productivity. But how will we recognise the impacts of climate change on ocean productivity? The most comprehensive information available on its global distribution comes from satellite ocean colour data. Now that over ten years of satellite-derived chlorophyll and productivity data have accumulated, can we begin to detect and attribute climate change-driven trends in productivity? Here we compare recent trends in satellite ocean colour data to longer-term time series from three biogeochemical models (GFDL, IPSL and NCAR. We find that detection of climate change-driven trends in the satellite data is confounded by the relatively short time series and large interannual and decadal variability in productivity. Thus, recent observed changes in chlorophyll, primary production and the size of the oligotrophic gyres cannot be unequivocally attributed to the impact of global climate change. Instead, our analyses suggest that a time series of ~40 years length is needed to distinguish a global warming trend from natural variability. In some regions, notably equatorial regions, detection times are predicted to be shorter (~20–30 years. Analysis of modelled chlorophyll and primary production from 2001–2100 suggests that, on average, the climate change-driven trend will not be unambiguously separable from decadal variability until ~2055. Because the magnitude of natural variability in chlorophyll and primary production is larger than, or similar to, the global warming trend, a consistent, decades-long data record must be established if the impact of climate change on ocean productivity is to be definitively detected.

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

    Science.gov (United States)

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

    2014-11-01

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

  3. Journal of Earth System Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Volume 110 Issue 1 March 2001 pp 77-86. Retrieval of vertical wind profiles during monsoon from satellite observed winds over the Indian Ocean using complex EOF analysis ... Altimeter data assimilation in the tropical Indian Ocean using water property conserving scheme · Bhasha M Mankad Rashmi Sharma Sujit Basu ...

  4. Regional variations in the fluxes of foraminifera carbonate, coccolithophorid carbonate and biogenic opal in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ramaswamy, V.; Gaye, B.

    Mass fluxes of diatom opal, planktonic foraminifera carbonate and coccolithophorid carbonate were measured with time-series sediment traps at six sites in the Arabian Sea, Bay of Bengal and Equatorial Indian Ocean (EIOT). The above fluxes were...

  5. First record of the synaptid holothurian Protankyrian protankyra Bidentata (Woodward and Barrett, 1858) from the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Deshmukh, A.; Ingole, B.S.; Mukharjee, I.; Sivadas, S.K.

    Sea cucumbers (holothurians) are marine invertebrates that are harvested worldwide, mostly for human consumption in Asian countries To date, only eight species of synaptid holothurians of the genus Protankyra have been reported from the Indian Ocean...

  6. Identification of fish populations with particular reference to the pelagic fish stocks of the Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Dwivedi, S.N.

    The most essential step in any fishery management is the identification of discrete fish populations. This is particularly important for the development of Indian Ocean pelagic fisheries. The simple signal character analysis of meristic or metric...

  7. Assessing Detecting and Deterring the Threat of Maritime Nuclear and Radiological Smuggling in the Western Indian Ocean Region

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M. Umer [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Cooperative Monitoring Center

    2017-03-01

    This paper proposes that current maritime smuggling routes in the western Indian Ocean region are similar to those in the past and that the motivations of terrorist groups and the presence of radioactive sources in the Indian Ocean littoral and other states present a significant security threat. The majority of regional terrorist groups have a hybrid structure, piggybacking on criminal activity to fund their terror activities. Additionally, states have used maritime routes in the Indian Ocean region to transport nuclear materials and missiles. Thus, the maritime dimension of such threats remains, and may be increasing. This paper focuses on issues, motivations, pathways, and methods to detect and interdict nuclear and radiological trafficking. It analyzes the potential use of maritime technology applications for radiation detection and presents recommendations for states and multinational nonproliferation advocacy organizations to address the threat in the Indian Ocean region.

  8. Tropical systems from the southwest Indian Ocean making landfall over the Limpopo River Basin, southern Africa: a historical perspective

    CSIR Research Space (South Africa)

    Malherbe, J

    2011-03-01

    Full Text Available The study provides perspective on the contribution of landfalling tropical systems (cyclones, depressions, storms and lows) from the southwest Indian Ocean (SWIO) towards rainfall over the eastern interior of southern Africa, over the period 1948...

  9. Formation of diapiric structure in the deformation zone, central Indian Ocean: A model from gravity and seismic reflection data

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.; Rao, D.G.; Neprochnov, Y.P.

    Analyses of bathymetry, gravity and seismic reflection data of the diffusive plate boundary in the central Indian Ocean reveal a new kind of deformed structure besides the well-reported structures of long-wavelength anticlinal basement rises...

  10. Primary productivity, phytoplankton standing crop and physico-chemical characteristics of the Antarctic and adjacent central Indian Ocean waters

    Digital Repository Service at National Institute of Oceanography (India)

    JiyalalRam, M.

    Primary productivity, phytoplankton pigments and physico-chemical properties were studied in Antarctic waters and adjoining Indian Ocean between 11 degrees and 67 degrees E longitudes from polynya region (60 degrees S) to equator during the austral...

  11. Okamejei ornata n. sp., a new deep-water skate (Elasmobranchii, Rajidae) from the northwestern Indian Ocean off Socotra Islands

    Science.gov (United States)

    Weigmann, Simon; Stehmann, Matthias F. W.; Thiel, Ralf

    2015-05-01

    A new species of the Indo-Pacific skate genus Okamejei is described based on 10 specimens caught around the Socotra Islands (northwestern Indian Ocean). The type series of Okamejei ornata n. sp. was sampled during cruise 17 of RV 'Vityaz' along the deep western Indian Ocean in 1988/89. The new species represents the fifth species of Okamejei in the western Indian Ocean and differs from its congeners in having a unique dorsal pattern of variable dark brown spots encircled with beige pigment and arranged into rosettes. The dorsal ground color is ocher, but the anterior snout is dusky. Compared to congeners in the western Indian Ocean, the new species has a shorter preorbital snout length, a greater orbit diameter, fewer pectoral radials, an intermediate distance between first gill slits, and an intermediate number of upper jaw tooth rows.

  12. Structure and evolution of the Afanasy Nikitin seamount, buried hills and 85 degrees E Ridge in the northeastern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.

    Geophysical data of the Afanasy Nikitin seamount (ANS), partly buried hills and 85 degrees E Ridge in the northeastern Indian Ocean were studied together with published seismic refraction results to understand genesis and evolution of the structures...

  13. Seasonal variability of the vertical fluxes of Globigerina bulloides (D'Orbigny) in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mohan, R.

    Settling particles intercepted using time-series sediment traps at seven locations in the northern Indian Ocean have been examined for the spatial and temporal variability in the distribution and fluxes of Globigerina bulloides (D'Orbigny...

  14. Seasonal variability of the vertical fluxes of @iGlobigerina bulloides@@ (D'Orbigny) in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mohan, R.

    Settling particles intercepted using time-series sediment traps at seven locations in the northern Indian Ocean have been examined for the spatial and temporal variability in the distribution and fluxes of @iGlobigerina bulloides@@ (@i...

  15. Seasonal variability of the vertical fluxes of Globigerina bulloides (D'Orbigny) in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Guptha, M.V.S.; Mohan, R.

    Settling particles intercepted using time-series sediment traps at seven locations in the northern Indian Ocean have been examined for the spatial and temporal variability in the distribution and fluxes of Globigerina bulloides (D...

  16. An atlas of mean distribution of precipitable water vapour over the tropical Indian Ocean for the year 1979

    Digital Repository Service at National Institute of Oceanography (India)

    RameshKumar, M.R.; Sathe, P.V.; Muraleedharan, P.M.; Rao, L.V.G.

    The monthly mean maps of the precipitable water (PW) over the tropical Indian Ocean are prepared using the data derived from the Nimbus 7 Scanning Multichannel Microwave Radiometer (SMMR) sensor for the period January to December, 1979. The PW...

  17. ECOSPACE : a pre-operational satellite system and services for ocean colour monitoring

    Science.gov (United States)

    Morel, André; Cerutti-Maori, Guy; Morel, Michel

    2017-11-01

    A permanent monitoring of the oceanic algal biomass (phytoplankton), of its photosynthetic activity, ecological and biogeochemical impact, or of its long-term response to changing physical and climatic conditions, is a crucial goal of scientific programmes (such as JGOFS, GLOBEC, LOICZ), as well as of international observing systems (such as GOOS, GCOS, IGOS). After a decade without ocean colour satellite-borne sensor, several instruments have been, or will be launched. They are increasingly sophisticated in their design and operation. Their complexity results from constraints for multipurpose mission (involving not only ocean, but also land and atmosphere), or from requirements for exploratory research projects and development of new methodologies for improved ocean colour interpretation and "advanced" products. In contrast, the proposed specific ECOSPACE mission is an ocean colour dedicated instrument, with a global monitoring vocation. It relies on known algorithms for accurate atmospheric corrections and aerosol load estimate over open ocean (about 96% of the whole ocean), and known algorithms for a meaningful quantification of the oceanic algal biomass (in terms of Chlorophyll concentration). The coastal zones are observed as well, and their particular features delineated : however, detailed studies that imply high ground resolution and more spectral channels are out of the scope of the present proposal. The ECOSPACE mission represents a feasibility demonstration ; more precisely it is a first step toward the setting up of an operational Satellite System and Services for a future continuous supply of stable, compatible, easy-to-merge ocean colour date products. In essence, such a Service would be similar to those already existing for meteorology and for some oceanic variables (e.g. sea level). Although new approaches to management and implementation over a short time scale are needed, the ECOSPACE project relies essentially on existing scientific and

  18. Seasonal variations of thermocline circulation and ventilation in the Indian Ocean

    Science.gov (United States)

    You, Yuzhu

    1997-05-01

    Two seasonal hydrographic data sets, including temperature, salinity, dissolved oxygen, and nutrients, are used in a mixing model which combines cluster analysis with optimum multiparameter analysis to determine the spreading and mixing of the thermocline waters in the Indian Ocean. The mixing model comprises a system of four major source water masses, which were identified in the thermocline through cluster analysis. They are Indian Central Water (ICW), North Indian Central Water (NICW) interpreted as aged ICW, Australasian Mediterranean Water (AAMW), and Red Sea Water (RSW)/Persian Gulf Water (PGW). The mixing ratios of these water masses are quantified and mapped on four isopycnal surfaces which span the thermocline from 150 to 600 m in the northern Indian Ocean, on two meridional sections along 60°E and 90°E, and on two zonal sections along 10°S and 6°N. The mixing ratios and pathways of the thermocline water masses show large seasonal variations, particularly in the upper 400-500 m of the thermocline. The most prominent signal of seasonal variation occurs in the Somali Current, the western boundary current, which appears only during the SW (summer) monsoon. The northward spreading of ICW into the equatorial and northern Indian Ocean is by way of the Somali Current centered at 300-400 m on the σθ=26.7 isopycnal surface during the summer monsoon and of the Equatorial Countercurrent during the NE (winter) monsoon. More ICW carried into the northern Indian Ocean during the summer monsoon is seen clearly in the zonal section along 6°N. NICW spreads southward through the western Indian Ocean and is stronger during the winter monsoon. AAMW appears in both seasons but is slightly stronger during the summer in the upper thermocline. The westward flow of AAMW is by way of the South Equatorial Current and slightly bends to the north on the σθ=26.7 isopycnal surface during the summer monsoon, indicative of its contribution to the western boundary current. Outflow

  19. An atlast of XBT thermal structures and TOPEX/POSEIDON sea surface heights in the north Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishna, V.V.; Ali, M.M.; Araligidad, N.; Shenoi, S.S.C.; Shum, C.K.; Yi, Y.

    the Indian XBT Program were used to plot the sub-surface thermal structures of the Indian Ocean for 1993 to 2003. Since these in situ measurements are just along the ship tracks, sea surface height observations from the TOPEX altimeter were also plotted over...

  20. PBDEs in the atmosphere over the Asian marginal seas, and the Indian and Atlantic oceans

    Science.gov (United States)

    Li, Jun; Li, Qilu; Gioia, Rosalinda; Zhang, Yanlin; Zhang, Gan; Li, Xiangdong; Spiro, Baruch; Bhatia, Ravinder S.; Jones, Kevin C.

    2011-12-01

    Air samples were collected from Jan 16 to Mar 14, 2008 onboard the Oceanic II- The Scholar Ship which navigated an east-west transect from Shanghai to Cape Verde, and polybrominated diphenyl ethers (PBDEs) were analyzed in these samples. PBDE concentrations in the atmosphere over the open seas were influenced by proximity to source areas and land, and air mass origins. The concentrations of Σ 21PBDEs over the East and South China Seas, the Bay of Bengal and the Andaman Sea, the Indian Ocean, and the Atlantic Ocean were 10.8 ± 6.13, 3.22 ± 1.57, 5.12 ± 3.56, and 2.87 ± 1.81 pg m -3, respectively. BDE-47 and -99 were the dominant congeners in all the samples, suggesting that the widely used commercial penta-BDE products were the original sources. Over some parts of Atlantic and Indian Ocean, daytime concentrations of BDE-47 and BDE-99 were higher than the concentrations at night. The strong atmospheric variability does not always coincide with a diurnal cycle, but the variability in air concentrations in such remote areas of the ocean remains strong. No significant trends were found for each of PBDE congener with latitude.

  1. Radiocarbon age of the recent deposits of the Indian Ocean western part (Seychelles)

    International Nuclear Information System (INIS)

    Svitoch, A.A.; Parunin, O.B.

    1988-01-01

    Mass radiocarbon dating according to Pleistocene precipitations of the islands of the Western Part of the Indian ocean is carried out. Time of formation of black-rock precipitations, low benches and island sandstones of low islands - middle-late Holocene - is established. Rocks of a reef complex are late Pleistocene. Relative concentration of dates according to various types of deposits points to the trustworthness and testifies about usefulness of radiocarbon analysis for stratigraphic and chronological separation of carbonate precipitations of islands of the equatorial zone of the ocean

  2. Observed sea-level rise in the north Indian Ocean coasts during the past century

    Digital Repository Service at National Institute of Oceanography (India)

    Unnikrishnan, A.S.

    Content-Type text/plain; charset=UTF-8 91 Observed sea-level rise in the north Indian Ocean coasts during the past century A. S. Unnikrishnan National Institute of Oceanography, Dona Paula, Goa-403004 unni@nio.org Introduction Sea-level... rise is one of the good indicators of global warming. Rise in sea level occurs mainly through melting of glaciers, thermal expansion due to ocean warming and some other processes of relatively smaller magnitudes. Sea level rise is a global...

  3. Relevance of bacterioplankton abundance and production in the oligotrophic equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, V.; Rodrigues, V.; Ramaiah, N.; Paul, J.T.

    , in some regions heterotrophic bacterial respiration (Del Giorgio et al. 1997) and production (Ameryk et al. 2005) sometimes far exceed the primary photosynthetic production. Unlike the Atlantic or Pacific Oceans, the Indian Ocean is landlocked... of the Yellow Sea. Mar Ecol Prog Ser 115:181–190 Cole JJ, Findlay S, Pace ML (1988) Bacterial production in fresh and saltwater ecosystem; a cross-system overview. Mar Ecol Prog Ser 43:1–10 Del Giorgio PA, Cole JJ, Cimbleris A (1997) Respiration rates...

  4. Development of an Indian Ocean moored buoy array for climate studies

    Digital Repository Service at National Institute of Oceanography (India)

    McPhaden, M.J.; Kuroda, Y.; Murty, V.S.N.

    of measurements to societal benefit. Chief among the principles is the need to distributed data openly in a timely manner. There is a preference for communication of data in real time to make it available at climate analysis and prediction centers.... This is essential to demonstrate the value of IndOOS and capture the potential societal benefits. 1. Introduction The Indian Ocean is unique among the three tropical ocean basins in that it is blocked at 25°N by the Asian land mass. Seasonal heating over...

  5. Effect of 3-D heterogeneous-earth on rheology inference of postseismic model following the 2012 Indian Ocean earthquake

    Science.gov (United States)

    Pratama, C.; Ito, T.; Sasajima, R.; Tabei, T.; Kimata, F.; Gunawan, E.; Ohta, Y.; Yamashina, T.; Ismail, N.; Muksin, U.; Maulida, P.; Meilano, I.; Nurdin, I.; Sugiyanto, D.; Efendi, J.

    2017-12-01

    Postseismic deformation following the 2012 Indian Ocean earthquake has been modeled by several studies (Han et al. 2015, Hu et al. 2016, Masuti et al. 2016). Although each study used different method and dataset, the previous studies constructed a significant difference of earth structure. Han et al. (2015) ignored subducting slab beneath Sumatra while Masuti et al. (2016) neglect sphericity of the earth. Hu et al. (2016) incorporated elastic slab and spherical earth but used uniform rigidity in each layer of the model. As a result, Han et al. (2015) model estimated one order higher Maxwell viscosity than the Hu et al. (2016) and half order lower Kelvin viscosity than the Masuti et al. (2016) model predicted. In the present study, we conduct a quantitative analysis of each heterogeneous geometry and parameter effect on rheology inference. We develop heterogeneous three-dimensional spherical-earth finite element models. We investigate the effect of subducting slab, spherical earth, and three-dimensional earth rigidity on estimated lithosphere-asthenosphere rheology beneath the Indian Ocean. A wide range of viscosity structure from time constant rheology to time dependent rheology was chosen as previous studies have been modeled. In order to evaluate actual displacement, we compared the model to the Global Navigation Satellite System (GNSS) observation. We incorporate the GNSS data from previous studies and introduce new GNSS site as a part of the Indonesian Continuously Operating Reference Stations (InaCORS) located in Sumatra that has not been used in the last analysis. As a preliminary result, we obtained the effect of the spherical earth and elastic slab when we assumed burgers rheology. The model that incorporates the sphericity of the earth needs a one third order lower viscosity than the model that neglects earth curvature. The model that includes elastic slab needs half order lower viscosity than the model that excluding the elastic slab.

  6. Penetration of bomb radiocarbon in the tropical Indian Ocean measured by means of accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Bard, E.; Arnold, M.; Maurice, P.; Monfray, P.; Duplessy, J.C.; Oestlund, H.G.

    1988-01-01

    Radiocarbon measurements performed on seawater samples by means of accelerator mass spectrometry (AMS) enable to reduce by a factor of 2000 the water sample size needed for the 14 C measurements. Therefore no chemical treatment on board the oceanographic vessel is required. Seventy-four AMS 14 C determinations on samples collected in the tropical-equatorial Indian Ocean during the second leg of the INDIGO program (1986) are presented and compared with the β-counting results obtained during the same campaign and the GEOSECS program (1978). A pronounced reduction of the equatorial 14 C deficit suggests that substantial amounts of bomb- 14 C are associated with the westward flowing Pacific water which enters the Indian Ocean via passages through the Indonesia Archipelago and/or to meridional mixing with 14 C-rich water of the southern subtropical gyre. (orig.)

  7. [Helminthic fauna of commercial fishes from the Saya-de-Malya bank (Indian Ocean)].

    Science.gov (United States)

    Parukhin, A M

    1988-01-01

    The data on infestation of 8 species of commercial fishes from Saya-de-Malya bank (the Indian Ocean) are presented. 43 helminth species were identified: 10 Monogenea species, 18 trematode, 7 cestode and 8 nematode species. The mature worms are observed to be related to a certain host, whereas the nematode and cestode larvae have wide specificity. High infestation degree by Anisakis larvae is found in fishes, especially in Carangidae. At the bank area fishes are found to be free from Acanthocephala while those Acanthocephala are found in fishes from other areas of the Indian Ocean which may be attributed to the specific diet at the Saya-de-Malya bank. On the whole the helminth fauna of fishes examined at the Saya-de-Malya bank does not demonstrate the endemic pattern. The most specific helminth species were found in some fish species.

  8. Not Just About the Science: Cold War Politics and the International Indian Ocean Expedition

    Science.gov (United States)

    Harper, K.

    2016-12-01

    The International Indian Ocean Expedition broke ground for a series of multi-national oceanographic expeditions starting in the late 1950s. In and of itself, it would have been historically significant—like the International Geophysical Year (1957-58)—for pulling together the international scientific community during the Cold War. However, US support for this and follow-on Indian Ocean expeditions were not just about the science; they were also about diplomacy, specifically efforts to bring non-aligned India into the US political orbit and out of the clutches of its Cold War enemy, the Soviet Union. This paper examines the behind-the-scenes efforts at the highest reaches of the US government to extract international political gain out of a large-scale scientific effort.

  9. Earth system feedback statistically extracted from the Indian Ocean deep-sea sediments recording Eocene hyperthermals.

    Science.gov (United States)

    Yasukawa, Kazutaka; Nakamura, Kentaro; Fujinaga, Koichiro; Ikehara, Minoru; Kato, Yasuhiro

    2017-09-12

    Multiple transient global warming events occurred during the early Palaeogene. Although these events, called hyperthermals, have been reported from around the globe, geologic records for the Indian Ocean are limited. In addition, the recovery processes from relatively modest hyperthermals are less constrained than those from the severest and well-studied hothouse called the Palaeocene-Eocene Thermal Maximum. In this study, we constructed a new and high-resolution geochemical dataset of deep-sea sediments clearly recording multiple Eocene hyperthermals in the Indian Ocean. We then statistically analysed the high-dimensional data matrix and extracted independent components corresponding to the biogeochemical responses to the hyperthermals. The productivity feedback commonly controls and efficiently sequesters the excess carbon in the recovery phases of the hyperthermals via an enhanced biological pump, regardless of the magnitude of the events. Meanwhile, this negative feedback is independent of nannoplankton assemblage changes generally recognised in relatively large environmental perturbations.

  10. Research opportunities and challenges in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Hood, R.; Naqvi, S.W.A.; Wiggert, J.; Goes, J.; Coles, V.; McCreary, J.; Bates, N.; Karuppasamy, P.K.; Mahowald, N.; Seitzinger, S.; Meyers, G.

    research questions. Ocean Currents and Variability The unique physical properties of the IO occur largely as a result of forcing by the strong semiannually reversing monsoon winds (Figure 1). These winds drive intense upwelling and seasonally reversing... the Pacifi c via the Indonesian Throughfl ow [Interna- tional CLIVAR Project Offi ce, 2006]. In gen- eral, there is a need to characterize and better understand the ecological and bio- geochemical responses to these physical forcings (Figure 1) as well...

  11. Seasonal water mass distribution in the Indonesian throughflow entering the Indian Ocean

    Science.gov (United States)

    Coatanoan, C.; Metzl, N.; Fieux, M.; Coste, B.

    1999-09-01

    A multiparametric approach is used to analyze the seasonal properties of water masses in the eastern Indian Ocean. The data were measured during two cruises of the Java Australia Dynamic Experiment (JADE) program carried out during two opposite seasons: August 1989 (SE monsoon) and February-March 1992 (NW monsoon). These cruises took place at the end of a La Niña event and during an El Niño episode, respectively. Seven sources have been identified in the studied region for the 200-800 m layer: the Subtropical Indian Water, the Indian Central Water, the modified Antarctic Intermediate Water, the Indonesian Subsurface Water, the Indonesian Intermediate Water, the Arabian Sea-Persian Gulf Water (AS-PGW), and the Arabian Sea-Red Sea Water (AS-RSW). The selected tracers are potential temperature, salinity and oxygen with mass conservation and positive mixing coefficients as constraints. The analysis indicates the proportion of each water source along the Australia-Bali section and into the Indonesian channels. Although no large changes are observed for Indonesian waters, significant seasonal variations are found for the southern and northern Indian Ocean water. During the NW monsoon, the contribution of the AS-RSW increases at the entrance of the Indonesian archipelago whereas the contribution of the south Indian waters decreases in the northwest Australia basin. In a complementary study, nutrients are introduced into the multiparametric analysis in order to more clearly separate the signature of the north Indian waters (AS-PGW, AS-RSW) and to provide supplementary information on the biological history of the water masses, which is compared to large-scale primary production estimates.

  12. Long range forecasting of summer monsoon rainfall from SST in the central equatorial Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y; Murthy, T.V.R.

    of summer monsoon rainfall from SST in the central equatorial Indian ocean Y. Sadhuram and T. V. Ramana Murthy National Institute of Oceanography, Regional Centre, 176, Lawson's Bay Colony, . Visakhapatnam-530017 ABSTRACT Severalprediction tedmiques have... and droughts associated with strong and weak monsoons greatly influence the economy of the country. Most of the droughts and floods are associated with EI-Nino and La- Nina respectively (Webster andYang3 and krishna Kumar et al\\. The relationship between ENSO...

  13. Influence of Mascarene High and Indian Ocean dipole on East African extreme weather events

    Directory of Open Access Journals (Sweden)

    Ogwang Bob Alex

    2015-01-01

    Full Text Available Extreme weather and climate events such as floods and droughts are common in East Africa, causing huge socio-economic losses. This study links the east African October-December (OND rainfall, Indian Ocean Dipole (IOD and Mascarene High (MH.Correlation analysis is applied to quantify the relationship between the index of IOD (Dipole Mode Index (DMI and OND rainfall. Results show that there exists a significant correlation between OND rainfall and DMI, with a correlation coefficient of 0.6. During dry years, MH is observed to intensify and align itself in the southeast-northwest orientation, stretching up to the continent, which in turn inhibits the influx of moisture from Indian Ocean into East Africa. During wet years, MH weakens, shifts to the east and aligns itself in the zonal orientation. Moisture from Indian Ocean is freely transported into east Africa during wet years. Analysis of the drought and flood years with respect to the different variables including wind, velocity potential and divergence/ convergence revealed that the drought (flood years were characterized by divergence (convergence in the lower troposphere and convergence (divergence at the upper level, implying sinking (rising motion, especially over the western Indian Ocean and the study area. Convergence at low level gives rise to vertical stretching, whereas divergence results in vertical shrinking, which suppresses convection due to subsidence. Positive IOD (Negative IOD event results into flood (drought in the region. The evolution of these phenomena can thus be keenly observed for utilization in the update of seasonal forecasts.

  14. Hydrological and chlorofluoromethane measurements of the Indonesian throughflow entering the Indian Ocean

    Science.gov (United States)

    Fieux, M.; Andrié, C.; Charriaud, E.; Ilahude, A. G.; Metzl, N.; Molcard, R.; Swallow, J. C.

    1996-05-01

    The Java Australia Dynamic Experiment high-resolution February-March 1992 conductivity-temperature-depth and chlorofluoromethane section obtained between Australia and Bali and on the sills between Flores, Sumba, Sawu, Roti, and the Australian continental shelf allows detailed examination of the water masses distribution and their inferred circulation. A sharp hydrological front between the Indonesian waters and the southern Indian Ocean waters is found between 13°S and 14°S in both seasons (February-March 1992 and August 1989). It separates the high-salinity surface waters to the south from the lower-salinity surface waters derived from the Indonesian Seas to the north. It reaches the surface in February 1992, whereas it was capped by a particularly low salinity surface layer in August 1989. Near Bali, the NW monsoon of February-March produces large intrusions of low-salinity water from the Java Sea, through Lombok Strait in the upper 100 m. At depth, the North Indian Intermediate Water, flowing along the Indonesian coast, brings salty, low-oxygen and low-chlorofluorocarbon water. It enters the Sawu Sea through Sumba Strait toward the east, while it undergoes strong mixing with the Indonesian Seas water. The primary pathway of the Indonesian waters is found north of the front and south of the North Indian Intermediate Water, between 13°S and 9°30'S, and the associated salinity minimum can be followed all across the Indian Ocean.

  15. Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 4, Volume IV: Inherent Optical Properties: Instruments, Characterizations, Field Measurements and Data Analysis Protocols

    Science.gov (United States)

    Mueller, J. L.; Fargion, G. S.; McClain, C. R. (Editor); Pegau, S.; Zanefeld, J. R. V.; Mitchell, B. G.; Kahru, M.; Wieland, J.; Stramska, M.

    2003-01-01

    This document stipulates protocols for measuring bio-optical and radiometric data for the Sensor Intercomparision and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project activities and algorithm development. The document is organized into 6 separate volumes as Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 4. Volume I: Introduction, Background, and Conventions; Volume II: Instrument Specifications, Characterization and Calibration; Volume III: Radiometric Measurements and Data Analysis Methods; Volume IV: Inherent Optical Properties: Instruments, Characterization, Field Measurements and Data Analysis Protocols; Volume V: Biogeochemical and Bio-Optical Measurements and Data Analysis Methods; Volume VI: Special Topics in Ocean Optics Protocols and Appendices. The earlier version of Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 3 is entirely superseded by the six volumes of Revision 4 listed above.

  16. Geographical representation of radial orbit perturbations due to ocean tides: Implications for satellite altimetry

    Science.gov (United States)

    Bettadpur, Srinivas V.; Eanes, Richard J.

    1994-01-01

    In analogy to the geographical representation of the zeroth-order radial orbit perturbations due to the static geopotential, similar relationships have been derived for radial orbit perturbations due to the ocean tides. At each location these perturbations are seen to be coherent with the tide height variations. The study of this singularity is of obvious importance to the estimation of ocean tides from satellite altimeter data. We derive analytical expressions for the sensitivity of altimeter derived ocean tide models to the ocean tide force model induced errors in the orbits of the altimeter satellite. In particular, we focus on characterizing and quantifying the nonresonant tidal orbit perturbations, which cannot be adjusted into the empirical accelerations or radial perturbation adjustments commonly used during orbit determination and in altimeter data processing. As an illustration of the utility of this technique, we study the differences between a TOPEX/POSEIDON-derived ocean tide model and the Cartwright and Ray 1991 Geosat model. This analysis shows that nearly 60% of the variance of this difference for M(sub 2) can be explained by the Geosat radial orbit eror due to the omission of coefficients from the GEM-T2 background ocean tide model. For O(sub 1), K(sub 1), S(sub 2), and K(sub 2) the orbital effects account for approximately 10 to 40% of the variances of these differences. The utility of this technique to assessment of the ocean tide induced errors in the TOPEX/POSEIDON-derived tide models is also discussed.

  17. The impact of Indian Ocean high pressure system on rainfall and stream flow

    International Nuclear Information System (INIS)

    Rehman, S.; Nasir, H.; Zia, S.S.; Ansari, W.A.; Salam, K.; Tayyab, N.

    2012-01-01

    Centre of Action approach is very useful in getting insight of rainfall and stream flow variability of specific region. Hameed et al. showed that Inter-annual variability of Gulf Stream north wall is influenced by low Icelandic pressure system and has more statistically significant correlation than North Atlantic Oscillation (NAO) with longitude of Icelandic low. This study also aims to explore possible relationships between rainfall and stream flow in Collie river catchment in Southwest Western Australia (SWWA) with Indian Ocean high pressure dynamics. The relationship between rainfall and stream flow with Indian Ocean high pressure system have been investigated using correlation analysis for early winter season (MJJA), lag correlation for MJJA versus SOND rainfall and stream flow are also calculated and found significant at 95% confidence level. By investigating the relationship between COA indices with rainfall and stream flow over the period 1976-2008, significant correlations suggests that rainfall and stream flow in Collie river basin is strongly influenced by COA indices. Multiple correlations between rainfall and stream flow with Indian Ocean high pressure (IOHPS and IOHLN) is 0.7 and 0.6 respectively. Centers of Action (COA) indices explain 51% and 36% of rainfall and stream flow respectively. The correlation between rainfall and stream flow with IOHPS is -0.4 and -0.3 whereas, with IOHLN is -0.47 and -0.52 respectively. (author)

  18. Sea level variability in the Arctic Ocean observed by satellite altimetry

    OpenAIRE

    Prandi, P.; Ablain, M.; Cazenave, A.; Picot, N.

    2012-01-01

    We investigate sea level variability in the Arctic Ocean from observations. Variability estimates are derived both at the basin scale and on smaller local spatial scales. The periods of the signals studied vary from high frequency (intra-annual) to long term trends. We also investigate the mechanisms responsible for the observed variability. Different data types are used, the main one being a recent reprocessing of satellite altimetry data...

  19. HY-2A satellite altimetric data evaluation in the Arctic ocean

    DEFF Research Database (Denmark)

    Cheng, Yongcun; Andersen, Ole Baltazar

    2014-01-01

    in the Arctic Ocean. The results demonstrates that the HY-2 data shows higher standard variation and mean sea level than AltiKa and CryoSat-2 data during HY-2 cycle 49 (20130803 and 20130817) with more available sea level measurements than CryoSat-2 satellite altimetry. Moreover, consistent sea level variation...... is observed from AltiKa and CryoSat-2 monthly sea level time series....

  20. Record of the Cretaceous magnetic quiet zone in the distal Bengal fan and its significance in understanding the evolutionary history of the northeastern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ramana, M.V.; Subrahmanyam, V.; Sarma, K.V.L.N.S.; Desa, M.; Rao, M.M.M.; Subrahmanyam, C.

    was collected during the International Indian Ocean Expedition Programme and subsequent expeditions to unravel the evolutionary history of Indian Ocean, not much was known about the age and nature of the ocean floor of the Bengal Fan but for few speculations...

  1. Geophysical investigations over a segment of the Central Indian Ridge, Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    KameshRaju, K.A.; Ramprasad, T.; Subrahmanyam, C.

    Swath bathymetric, gravity, and magnetic studies were carried out over a 55 km long segment of the Central Indian Ridge. The ridge is characterized by 12 to 15 km wide rift valley bounded by steep walls and prominent volcanic constructional ridges...

  2. Long-term change analysis of satellite-based evapotranspiration over Indian vegetated surface

    Science.gov (United States)

    Gupta, Shweta; Bhattacharya, Bimal K.; Krishna, Akhouri P.

    2016-05-01

    In the present study, trend of satellite based annual evapotranspiration (ET) and natural forcing factors responsible for this were analyzed. Thirty years (1981-2010) of ET data at 0.08° grid resolution, generated over Indian region from opticalthermal observations from NOAA PAL and MODIS AQUA satellites, were used. Long-term data on gridded (0.5° x 0.5°) annual rainfall (RF), annual mean surface soil moisture (SSM) ERS scatterometer at 25 km resolution and annual mean incoming shortwave radiation from MERRA-2D reanalysis were also analyzed. Mann-Kendall tests were performed with time series data for trend analysis. Mean annual ET loss from Indian ago-ecosystem was found to be almost double (1100 Cubic Km) than Indian forest ecosystem (550 Cubic Km). Rainfed vegetation systems such as forest, rainfed cropland, grassland showed declining ET trend @ - 4.8, -0.6 &-0.4 Cubic Kmyr-1, respectively during 30 years. Irrigated cropland initially showed ET decline upto 1995 @ -0.8 cubic Kmyr-1 which could possibly be due to solar dimming followed by increasing ET @ 0.9 cubic Kmyr-1 after 1995. A cross-over point was detected between forest ET decline and ET increase in irrigated cropland during 2008. During 2001-2010, the four agriculturally important Indian states eastern, central, western and southern showed significantly increasing ET trend with S-score of 15-25 and Z-score of 1.09-2.9. Increasing ET in western and southern states was found to be coupled with increase in annual rainfall and SSM. But in eastern and central states no significant trend in rainfall was observed though significant increase in ET was noticed. The study recommended to investigate the influence of anthropogenic factors such as increase in area under irrigation, increased use of water for irrigation through ground water pumping, change in cropping pattern and cultivars on increasing ET.

  3. Seasonal and geographic variation of southern blue whale subspecies in the Indian Ocean.

    Directory of Open Access Journals (Sweden)

    Flore Samaran

    Full Text Available Understanding the seasonal movements and distribution patterns of migratory species over ocean basin scales is vital for appropriate conservation and management measures. However, assessing populations over remote regions is challenging, particularly if they are rare. Blue whales (Balaenoptera musculus spp are an endangered species found in the Southern and Indian Oceans. Here two recognized subspecies of blue whales and, based on passive acoustic monitoring, four "acoustic populations" occur. Three of these are pygmy blue whale (B.m. brevicauda populations while the fourth is the Antarctic blue whale (B.m. intermedia. Past whaling catches have dramatically reduced their numbers but recent acoustic recordings show that these oceans are still important habitat for blue whales. Presently little is known about the seasonal movements and degree of overlap of these four populations, particularly in the central Indian Ocean. We examined the geographic and seasonal occurrence of different blue whale acoustic populations using one year of passive acoustic recording from three sites located at different latitudes in the Indian Ocean. The vocalizations of the different blue whale subspecies and acoustic populations were recorded seasonally in different regions. For some call types and locations, there was spatial and temporal overlap, particularly between Antarctic and different pygmy blue whale acoustic populations. Except on the southernmost hydrophone, all three pygmy blue whale acoustic populations were found at different sites or during different seasons, which further suggests that these populations are generally geographically distinct. This unusual blue whale diversity in sub-Antarctic and sub-tropical waters indicates the importance of the area for blue whales in these former whaling grounds.

  4. A case study of GWE satellite data impact on GLA assimilation analyses of two ocean cyclones

    Science.gov (United States)

    Gallimore, R. G.; Johnson, D. R.

    1986-01-01

    The effects of the Global Weather Experiment (GWE) data obtained on January 18-20, 1979 on Goddard Laboratory for Atmospheres assimilation analyses of simultaneous cyclones in the western Pacific and Atlantic oceans are examined. The ability of satellite data within assimilation models to determine the baroclinic structures of developing extratropical cyclones is evaluated. The impact of the satellite data on the amplitude and phase of the temperature structure within the storm domain, potential energy, and baroclinic growth rate is studied. The GWE data are compared with Data Systems Test results. It is noted that it is necessary to characterize satellite effects on the baroclinic structure of cyclone waves which degrade numerical weather predictions of cyclogenesis.

  5. Upper ocean circulation modulation by phytoplankton concentration in the Equatorial Pacific and the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Nakamoto, S.; PrasannaKumar, S.; Oberhuber, J.M.; Sammarco, P.; Muneyama, K.; Sato, T.; AjoyKumar, A.; Frouin, R.

    gradient in the upper ocean. This strengthens the geostrophically balanced westward currents in both side of the equatorial wave-guide (within 5 degree bands). Once these currents reach the western Pacific coast, they feed the Equatorial undercurrent (EUC...

  6. Oceanic Geoid and Tides Obtained from GEOS-3 Satellite Data in the Northwestern Atlantic Ocean

    Science.gov (United States)

    Won, I. J.; Miller, L. S.

    1978-01-01

    Two sets of GEO-3 altimeter data which fall within about a 2.5 degree width are analyzed for ocean geoid and tides. One set covers a linear path from Newfoundland to Cuba and the other from Puerto Rico to the North Carolina coast. Forty different analyses using various parameters are performed in order to investigate convergence. Profiles of the geoid and four tides, M sub 2 O sub 1, S sub 2, and K sub 1, are obtained along the two strips. The results demonstrate convergent solutions for all forty cases and show, within expectation, fair agreement with those obtained from the MODE deep-sea tide gauge. It is also shown that the oceanic geoid obtained through this analysis can potentially improve the short wavelength structure over existing geoid models.

  7. A Comprehensive Plan for the Long-Term Calibration and Validation of Oceanic Biogeochemical Satellite Data

    Science.gov (United States)

    Hooker, Stanford B.; McClain, Charles R.; Mannino, Antonio

    2007-01-01

    The primary objective of this planning document is to establish a long-term capability and validating oceanic biogeochemical satellite data. It is a pragmatic solution to a practical problem based primarily o the lessons learned from prior satellite missions. All of the plan's elements are seen to be interdependent, so a horizontal organizational scheme is anticipated wherein the overall leadership comes from the NASA Ocean Biology and Biogeochemistry (OBB) Program Manager and the entire enterprise is split into two components of equal sature: calibration and validation plus satellite data processing. The detailed elements of the activity are based on the basic tasks of the two main components plus the current objectives of the Carbon Cycle and Ecosystems Roadmap. The former is distinguished by an internal core set of responsibilities and the latter is facilitated through an external connecting-core ring of competed or contracted activities. The core elements for the calibration and validation component include a) publish protocols and performance metrics; b) verify uncertainty budgets; c) manage the development and evaluation of instrumentation; and d) coordinate international partnerships. The core elements for the satellite data processing component are e) process and reprocess multisensor data; f) acquire, distribute, and archive data products; and g) implement new data products. Both components have shared responsibilities for initializing and temporally monitoring satellite calibration. Connecting-core elements include (but are not restricted to) atmospheric correction and characterization, standards and traceability, instrument and analysis round robins, field campaigns and vicarious calibration sites, in situ database, bio-optical algorithm (and product) validation, satellite characterization and vicarious calibration, and image processing software. The plan also includes an accountability process, creating a Calibration and Validation Team (to help manage

  8. Variability in the mechanisms controlling Southern Ocean phytoplankton bloom phenology in an ocean model and satellite observations

    Science.gov (United States)

    Rohr, Tyler; Long, Matthew C.; Kavanaugh, Maria T.; Lindsay, Keith; Doney, Scott C.

    2017-05-01

    A coupled global numerical simulation (conducted with the Community Earth System Model) is used in conjunction with satellite remote sensing observations to examine the role of top-down (grazing pressure) and bottom-up (light, nutrients) controls on marine phytoplankton bloom dynamics in the Southern Ocean. Phytoplankton seasonal phenology is evaluated in the context of the recently proposed "disturbance-recovery" hypothesis relative to more traditional, exclusively "bottom-up" frameworks. All blooms occur when phytoplankton division rates exceed loss rates to permit sustained net population growth; however, the nature of this decoupling period varies regionally in Community Earth System Model. Regional case studies illustrate how unique pathways allow blooms to emerge despite very poor division rates or very strong grazing rates. In the Subantarctic, southeast Pacific small spring blooms initiate early cooccurring with deep mixing and low division rates, consistent with the disturbance-recovery hypothesis. Similar systematics are present in the Subantarctic, southwest Atlantic during the spring but are eclipsed by a subsequent, larger summer bloom that is coincident with shallow mixing and the annual maximum in division rates, consistent with a bottom-up, light limited framework. In the model simulation, increased iron stress prevents a similar summer bloom in the southeast Pacific. In the simulated Antarctic zone (70°S-65°S) seasonal sea ice acts as a dominant phytoplankton-zooplankton decoupling agent, triggering a delayed but substantial bloom as ice recedes. Satellite ocean color remote sensing and ocean physical reanalysis products do not precisely match model-predicted phenology, but observed patterns do indicate regional variability in mechanism across the Atlantic and Pacific.

  9. Satellite Remote Sensing of Ocean Winds, Surface Waves and Surface Currents during the Hurricanes

    Science.gov (United States)

    Zhang, G.; Perrie, W. A.; Liu, G.; Zhang, L.

    2017-12-01

    Hurricanes over the ocean have been observed by spaceborne aperture radar (SAR) since the first SAR images were available in 1978. SAR has high spatial resolution (about 1 km), relatively large coverage and capability for observations during almost all-weather, day-and-night conditions. In this study, seven C-band RADARSAT-2 dual-polarized (VV and VH) ScanSAR wide images from the Canadian Space Agency (CSA) Hurricane Watch Program in 2017 are collected over five hurricanes: Harvey, Irma, Maria, Nate, and Ophelia. We retrieve the ocean winds by applying our C-band Cross-Polarization Coupled-Parameters Ocean (C-3PO) wind retrieval model [Zhang et al., 2017, IEEE TGRS] to the SAR images. Ocean waves are estimated by applying a relationship based on the fetch- and duration-limited nature of wave growth inside hurricanes [Hwang et al., 2016; 2017, J. Phys. Ocean.]. We estimate the ocean surface currents using the Doppler Shift extracted from VV-polarized SAR images [Kang et al., 2016, IEEE TGRS]. C-3PO model is based on theoretical analysis of ocean surface waves and SAR microwave backscatter. Based on the retrieved ocean winds, we estimate the hurricane center locations, maxima wind speeds, and radii of the five hurricanes by adopting the SHEW model (Symmetric Hurricane Estimates for Wind) by Zhang et al. [2017, IEEE TGRS]. Thus, we investigate possible relations between hurricane structures and intensities, and especially some possible effects of the asymmetrical characteristics on changes in the hurricane intensities, such as the eyewall replacement cycle. The three SAR images of Ophelia include the north coast of Ireland and east coast of Scotland allowing study of ocean surface currents respond to the hurricane. A system of methods capable of observing marine winds, surface waves, and surface currents from satellites is of value, even if these data are only available in near real-time or from SAR-related satellite images. Insight into high resolution ocean winds

  10. Cryptic lineage differentiation among Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the northwest Indian Ocean.

    Science.gov (United States)

    Gray, H W I; Nishida, S; Welch, A J; Moura, A E; Tanabe, S; Kiani, M S; Culloch, R; Möller, L; Natoli, A; Ponnampalam, L S; Minton, G; Gore, M; Collins, T; Willson, A; Baldwin, R; Hoelzel, A R

    2018-05-01

    Phylogeography can provide insight into the potential for speciation and identify geographic regions and evolutionary processes associated with species richness and evolutionary endemism. In the marine environment, highly mobile species sometimes show structured patterns of diversity, but the processes isolating populations and promoting differentiation are often unclear. The Delphinidae (oceanic dolphins) are a striking case in point and, in particular, bottlenose dolphins (Tursiops spp.). Understanding the radiation of species in this genus is likely to provide broader inference about the processes that determine patterns of biogeography and speciation, because both fine-scale structure over a range of kilometers and relative panmixia over an oceanic range are known for Tursiops populations. In our study, novel Tursiops spp. sequences from the northwest Indian Ocean (including mitogenomes and two nuDNA loci) are included in a worldwide Tursiops spp. phylogeographic analysis. We discover a new 'aduncus' type lineage in the Arabian Sea (off India, Pakistan and Oman) that diverged from the Australasian lineage ∼261 Ka. Effective management of coastal dolphins in the region will need to consider this new lineage as an evolutionarily significant unit. We propose that the establishment of this lineage could have been in response to climate change during the Pleistocene and show data supporting hypotheses for multiple divergence events, including vicariance across the Indo-Pacific barrier and in the northwest Indian Ocean. These data provide valuable transferable inference on the potential mechanisms for population and species differentiation across this geographic range. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. New sites of Australasian microtektites in the central Indian Ocean: Implications for the location and size of source crater

    Digital Repository Service at National Institute of Oceanography (India)

    ShyamPrasad, M.; Mahale, V.P.; Kodagali, V.N.

    Fifteen new Australasian microtektite sites have been identified along a transect roughly N-S in the central Indian Ocean. These locations, in addition to the existing 46 sites, total to 61 microtektite sites in the oceans. We carried out regression...

  12. Distribution of runup heights of the December 26, 2004 tsunami in the Indian Ocean

    Science.gov (United States)

    Choi, Byung Ho; Hong, Sung Jin; Pelinovsky, Efim

    2006-07-01

    A massive earthquake with magnitude 9.3 occurred on December 26, 2004 off the northern Sumatra generated huge tsunami waves affected many coastal countries in the Indian Ocean. A number of field surveys have been performed after this tsunami event; in particular, several surveys in the south/east coast of India, Andaman and Nicobar Islands, Sri Lanka, Sumatra, Malaysia, and Thailand have been organized by the Korean Society of Coastal and Ocean Engineers from January to August 2005. Spatial distribution of the tsunami runup is used to analyze the distribution function of the wave heights on different coasts. Theoretical interpretation of this distribution is associated with random coastal bathymetry and coastline led to the log-normal functions. Observed data also are in a very good agreement with log-normal distribution confirming the important role of the variable ocean bathymetry in the formation of the irregular wave height distribution along the coasts.

  13. Multielemental analysis of ferromanganese nodules from Central Indian Ocean Basin by PIXE

    International Nuclear Information System (INIS)

    Dutta, R. K.; Vijayan, V.; Ghosh, S.; Chakravortty, V.

    1997-01-01

    Ferromanganese nodules found on the Ocean bed are complex heterogeneous mixtures of several components. Two nodules from Central Indian Ocean Basin (CIOB) were analysed by proton induced X-ray emission (PIXE) technique using 3UD Tandem pelletron. The precision and the accuracy of this technique for chemical analyses has been confirmed by analysing USGS Geological Standards. Thick sample targets were bombarded by 3 MeV protons for the multielemental analysis. GUPIX-96 software was used for spectral data analysis. Quantitative estimate of K, Ca, Tl, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Ba, Ce, Tl and Pb has been ascertained. The occurrence of Ga, Ge, Rb and Zr in nodules from this region is reported for the first time. The role of manganese and iron oxide phases in determining the uptake of various trace elements from ocean water and bottom sediment pore water has been discussed. (author)

  14. Indian Ocean Dipole and El Nino/Southern Oscillation impacts on regional chlorophyll anomalies in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Currie, J.C.; Lengaigne, M.; Vialard, J.; Kaplan, D.M.; Aumont, O.; Naqvi, S.W.A.; Maury, O.

    Offshore Node, South African Environmental Observation Network, Cape Town, South Africa 3Institut de Recherche pour le Développement, Laboratoire d’Océanographie et du Climat: Expérimentation et Approches Numériques, UMR 7617, Université Pierre et Marie... that relate to changes in ascending and descending branches of the Walker circu- lation (Du et al., 2009; Reason et al., 2000; Venzke et al., 2000). In turn, such physical perturbations can affect the biol- ogy in local and distant oceans (Ménard et al., 2007...

  15. Relocation of earthquakes at southwestern Indian Ocean Ridge and its tectonic significance

    Science.gov (United States)

    Luo, W.; Zhao, M.; Haridhi, H.; Lee, C. S.; Qiu, X.; Zhang, J.

    2015-12-01

    The southwest Indian Ridge (SWIR) is a typical ultra-slow spreading ridge (Dick et al., 2003) and further plate boundary where the earthquakes often occurred. Due to the lack of the seismic stations in SWIR, positioning of earthquakes and micro-earthquakes is not accurate. The Ocean Bottom Seismometers (OBS) seismic experiment was carried out for the first time in the SWIR 49 ° 39 'E from Jan. to March, 2010 (Zhao et al., 2013). These deployed OBS also recorded the earthquakes' waveforms during the experiment. Two earthquakes occurred respectively in Feb. 7 and Feb. 9, 2010 with the same magnitude of 4.4 mb. These two earthquakes were relocated using the software HYPOSAT based on the spectrum analysis and band-pass (3-5 Hz) filtering and picking up the travel-times of Pn and Sn. Results of hypocentral determinations show that there location error is decreased significantly by joined OBS's recording data. This study do not only provide the experiences for the next step deploying long-term wide-band OBSs, but also deepen understanding of the structure of SWIR and clarify the nature of plate tectonic motivation. This research was granted by the Natural Science Foundation of China (41176053, 91028002, 91428204). Keywords: southwest Indian Ridge (SWIR), relocation of earthquakes, Ocean Bottom Seismometers (OBS), HYPOSAT References:[1] Dick, H. J. B., Lin J., Schouten H. 2003. An ultraslow-spreading class of ocean ridge. Nature, 426(6965): 405-412. [2] Zhao M. H., et al. 2013. Three-dimensional seismic structure of the Dragon Flag oceanic core complex at the ultraslow spreading Southwest Indian Ridge (49°39' E). Geochemistry Geophysics Geosystems, 14(10): 4544-4563.

  16. Twentieth century North Atlantic climate change. Part II: Understanding the effect of Indian Ocean warming

    Energy Technology Data Exchange (ETDEWEB)

    Hoerling, M.P.; Xu, T.; Bates, G.T. [Climate Diagnostics Center NOAA, Boulder, CO 80305-3328 (United States); Hurrell, J.W.; Phillips, A.S. [National Center for Atmospheric Research, Boulder, CO (United States)

    2004-09-01

    Ensembles of atmospheric general circulation model (AGCM) experiments are used in an effort to understand the boreal winter Northern Hemisphere (NH) extratropical climate response to the observed warming of tropical sea surface temperatures (SSTs) over the last half of the twentieth Century. Specifically, we inquire about the origins of unusual, if not unprecedented, changes in the wintertime North Atlantic and European climate that are well described by a linear trend in most indices of the North Atlantic Oscillation (NAO). The simulated NH atmospheric response to the linear trend component of tropic-wide SST change since 1950 projects strongly onto the positive polarity of the NAO and is a hemispheric pattern distinguished by decreased (increased) Arctic (middle latitude) sea level pressure. Progressive warming of the Indian Ocean is the principal contributor to this wintertime extratropical response, as shown through additional AGCM ensembles forced with only the SST trend in that sector. The Indian Ocean influence is further established through the reproducibility of results across three different models forced with identical, idealized patterns of the observed warming. Examination of the transient atmospheric adjustment to a sudden ''switch-on'' of an Indian Ocean SST anomaly reveals that the North Atlantic response is not consistent with linear theory and most likely involves synoptic eddy feedbacks associated with changes in the North Atlantic storm track. The tropical SST control exerted over twentieth century regional climate underlies the importance of determining the future course of tropical SST for regional climate change and its uncertainty. Better understanding of the extratropical responses to different, plausible trajectories of the tropical oceans is key to such efforts. (orig.)

  17. Genetic Isolation among the Northwestern, Southwestern and Central-Eastern Indian Ocean Populations of the Pronghorn Spiny Lobster Panulirus penicillatus

    Directory of Open Access Journals (Sweden)

    Muhamad Fadry Abdullah

    2014-05-01

    Full Text Available The pronghorn spiny lobster Panulirus penicillatus is a highly valuable species which is widely distributed in Indo-West Pacific and Eastern Pacific regions. Mitochondrial DNA control region sequences (566–571 bp were determined to investigate the population genetic structure of this species in the Indian Ocean. In total, 236 adult individuals of Panulirus penicillatus were collected from five locations in the Indian Ocean region. Almost all individuals had a unique haplotype. Intrapopulation haplotype (h and nucleotide (π diversities were high for each locality, ranging from h = 0.9986–1.0000 and π = 0.031593–0.043441. We observed distinct genetic isolation of population located at the northwestern and southwestern edge of the species range. Gene flow was found within localities in the central and eastern region of the Indian Ocean, probably resulting from an extended planktonic larval stage and prevailing ocean currents.

  18. Association between mean and interannual equatorial Indian Ocean subsurface temperature bias in a coupled model

    Science.gov (United States)

    Srinivas, G.; Chowdary, Jasti S.; Gnanaseelan, C.; Prasad, K. V. S. R.; Karmakar, Ananya; Parekh, Anant

    2018-03-01

    In the present study the association between mean and interannual subsurface temperature bias over the equatorial Indian Ocean (EIO) is investigated during boreal summer (June through September; JJAS) in the National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFSv2) hindcast. Anomalously high subsurface warm bias (greater than 3 °C) over the eastern EIO (EEIO) region is noted in CFSv2 during summer, which is higher compared to other parts of the tropical Indian Ocean. Prominent eastward current bias in the upper 100 m over the EIO region induced by anomalous westerly winds is primarily responsible for subsurface temperature bias. The eastward currents transport warm water to the EEIO and is pushed down to subsurface due to downwelling. Thus biases in both horizontal and vertical currents over the EIO region support subsurface warm bias. The evolution of systematic subsurface warm bias in the model shows strong interannual variability. These maximum subsurface warming episodes over the EEIO are mainly associated with La Niña like forcing. Strong convergence of low level winds over the EEIO and Maritime continent enhanced the westerly wind bias over the EIO during maximum warming years. This low level convergence of wind is induced by the bias in the gradient in the mean sea level pressure with positive bias over western EIO and negative bias over EEIO and parts of western Pacific. Consequently, changes in the atmospheric circulation associated with La Niña like conditions affected the ocean dynamics by modulating the current bias thereby enhancing the subsurface warm bias over the EEIO. It is identified that EEIO subsurface warming is stronger when La Niña co-occurred with negative Indian Ocean Dipole events as compared to La Niña only years in the model. Ocean general circulation model (OGCM) experiments forced with CFSv2 winds clearly support our hypothesis that ocean dynamics influenced by westerly winds bias is primarily

  19. Radiocarbon Content of Dissolved Organic Carbon in the South Indian Ocean

    Science.gov (United States)

    Bercovici, S. K.; McNichol, A. P.; Xu, L.; Hansell, D. A.

    2018-01-01

    We report four profiles of the radiocarbon content of dissolved organic carbon (DOC) spanning the South Indian Ocean (SIO), ranging from the Polar Front (56°S) to the subtropics (29°S). Surface waters held mean DOC Δ14C values of -426 ± 6‰ ( 4,400 14C years) at the Polar Front and DOC Δ14C values of -252 ± 22‰ ( 2,000 14C years) in the subtropics. At depth, Circumpolar Deep Waters held DOC Δ14C values of -491 ± 13‰ ( 5,400 years), while values in Indian Deep Water were more depleted, holding DOC Δ14C values of -503 ± 8‰ ( 5,600 14C years). High-salinity North Atlantic Deep Water intruding into the deep SIO had a distinctly less depleted DOC Δ14C value of -481 ± 8‰ ( 5,100 14C years). We use multiple linear regression to assess the dynamics of DOC Δ14C values in the deep Indian Ocean, finding that their distribution is characteristic of water masses in that region.

  20. Evaluation of the ion-density measurements by the Indian satellite SROSS-C2

    Science.gov (United States)

    Subrahmanyam, P.; Jain, A. R.; Maini, H. K.; Bahl, M.; Das, Rupesh M.; Garg, S. C.; Niranjan, K.

    2010-12-01

    The ion and electron F region plasma measurements made by the ion and electron Retarding Potential Analyzers (RPAs) onboard the Indian satellite SROSS-C2, have yielded excellent data set over the Indian region for more than half a solar cycle, after the SROSS-C2 launch in May 1994. The absolute ion density, ion temperature, and ion composition parameters are derived from these in situ measurements and used by many workers. In this paper the absolute values of ion density derived from the ion RPA measurements are compared and evaluated with the measurements made by ground-based ionosondes located in the Indian region and close to the SROSS-C2 orbital path. It is shown that a slight adjustment in efficiency factor of the ion RPA sensor brings the in situ measurements much closer to those obtained from the ground-based ionosonde measurements taking into account the model calculations. It may be mentioned that this is a correction to the ion density measurement by SROSS-C2 by a fixed proportion (14-11.4%). The effect of change in efficiency factor on the ion current, which is used to deduce the ion number density, is demonstrated and discussed.

  1. Phytoplankton community structure at the juncture of the Agulhas return front and subtropical front in the Indian Ocean sector of Southern Ocean: Bottom-up and top-down control

    Digital Repository Service at National Institute of Oceanography (India)

    Naik, R.K.; George, J.V.; Soares, M.A.; Devi, A.; Anilkumar, N.; Roy, R.; Bhaskar, P.V.; Murukesh, N.; Achuthankutty, C.T.

    The juncture of the Agulhas Return Front (ARF) and Subtropical Front (STF) in the Indian Ocean sector of Southern Ocean (SO) is characterized by high mesoscale turbulence, which results in sporadic, short lived phytoplankton proliferation The biota...

  2. Propagation of Atlantic Ocean swells in the north Indian Ocean: A case study

    Digital Repository Service at National Institute of Oceanography (India)

    Samiksha, S.V.; Vethamony, P.; Aboobacker, V.M.; Rashmi, R.

    An analysis of altimeter significant wave height data of May 2007 revealed the occurrence of an extreme weather event off southern tip of South Africa in the Atlantic Ocean, and generation of a series of very high swells at 40 degrees S...

  3. Zooplankton standing stock and diversity along an oceanic track in the western Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Madhupratap, M.

    Zooplankton samples were collected from 13 stations situated in the oceanic realm between latitudes 8 degrees 49 minutes N and 19 degrees 48 minutes S in January-February, 1981. Standing stock varied between 1.6 and 10.4 ml/100 m@u3...

  4. Prediction of the Sun-Glint Locations for the Communication, Ocean and Meteorological Satellite

    Directory of Open Access Journals (Sweden)

    Jae-Ik Park

    2005-09-01

    Full Text Available For the Communication, Ocean and Meteorological Satellite (COMS which will be launched in 2008, an algorithm for finding the precise location of the sun-glint point on the ocean surface is studied. The precise locations of the sun-glint are estimated by considering azimuth and elevation angles of Sun-satellite-Earth geometric position and the law of reflection. The obtained nonlinear equations are solved by using the Newton-Raphson method. As a result, when COMS is located at 116.2°E or 128.2°E longitude, the sun-glint covers region of ±10° (N-S latitude and 80-150° (E-W longitude. The diurnal path of the sun-glint in the southern hemisphere is curved towards the North Pole, and the path in the northern hemisphere is forwards the south pole. The algorithm presented in this paper can be applied to predict the precise location of sun-glint region in any other geostationary satellites.

  5. Seasonal variability of salinity and salt transport in the northern Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    D’Addezio, J.M.; Subrahmanyam, B.; Nyadjro, E.S.; Murty, V.S.N.

    , University of South Carolina, Columbia, SC 29208 2Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC 29208 3 Department of Physics, University of New Orleans, New Orleans, LA 70148 4Council of Scientific and Industrial... are underrepresented in the literature. The almost 3 year record provided by Aquarius gives us reason to reexamine this seasonally variable region with the aid of this new observational dataset as well as analyze how the satellite-derived SSS compares with the Argo...

  6. Physical, currents, nutrients, and other data from bottle and GEK casts from the FUJI and SHIRASE in the Indian Ocean, North Pacific Ocean, South Pacific Ocean, and Southern Oceans (> 60 degrees South) from 06 December 1965 to 10 January 1994 (NODC Accession 0000039)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical, currents, nutrients, and other data were collected from bottle and GEK casts from the FUJI and SHIRASE in the Indian Ocean and other locations from 06...

  7. Variability of Evaporation and Precipitation over the Ocean from Satellite Data

    Science.gov (United States)

    Malinin, V. N.; Gordeeva, S. M.

    2017-12-01

    HOAPS-3 and PMWC satellite archives for 1988-2008 are used to estimate moisture-exchange components between the ocean and atmosphere (evaporation, precipitation, and the difference between them or effective evaporation). Moisture-exchange components for the entire World Ocean and for the North Atlantic Ocean within 30°-60° N are calculated. A strong overestimation of the global values of effective evaporation by HOAPS data (mainly caused by a decrease in precipitation) is shown. In the interannual variability of effective evaporation, there is clearly an overestimated positive trend, which contradicts the real increase in the Global Sea Level. Large systematic errors in moisture-exchange components are revealed for the North Atlantic water area. According to HOAPS data, there is a significant underestimation of evaporation and effective evaporation. According to PMWC data, the amount of precipitation is significantly overestimated and evaporation is underestimated. As a consequence, effective evaporation becomes negative, which is impossible. Low accuracy in the estimation of moisture-exchange components and the need to improve old estimates and develop new evaporation and precipitation databases based on satellite data are noted.

  8. Global assessment of ocean carbon export by combining satellite observations and food-web models

    Science.gov (United States)

    Siegel, D. A.; Buesseler, K. O.; Doney, S. C.; Sailley, S. F.; Behrenfeld, M. J.; Boyd, P. W.

    2014-03-01

    The export of organic carbon from the surface ocean by sinking particles is an important, yet highly uncertain, component of the global carbon cycle. Here we introduce a mechanistic assessment of the global ocean carbon export using satellite observations, including determinations of net primary production and the slope of the particle size spectrum, to drive a food-web model that estimates the production of sinking zooplankton feces and algal aggregates comprising the sinking particle flux at the base of the euphotic zone. The synthesis of observations and models reveals fundamentally different and ecologically consistent regional-scale patterns in export and export efficiency not found in previous global carbon export assessments. The model reproduces regional-scale particle export field observations and predicts a climatological mean global carbon export from the euphotic zone of 6 Pg C yr-1. Global export estimates show small variation (typically model parameter values. The model is also robust to the choices of the satellite data products used and enables interannual changes to be quantified. The present synthesis of observations and models provides a path for quantifying the ocean's biological pump.

  9. Oceanographic profile temperature, salinity, oxygen, and nutrients measurements collected using bottle from the Iselin Columbus in the Indian Ocean (Somalia Coast) (NODC Accession 0002225)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile and nutrients data were collected using bottle casts from the COLUMBUS ISELIN in the Indian Ocean. Data were collected from 26 February 1979 to...

  10. Zooplankton species identities collected from zooplankton net casts in Indian Ocean from 17 February 1960 to 23 July 1962 (NODC Accession 9400059)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton species identities and other data were collected using zooplankton net casts in the Indian Ocean. Data were collected from 17 February 1960 to 23 July...

  11. Physical, nutrients, and other data from CTD, MBT, XBT, and bottle casts from the Indian Ocean from 01 January 1976 to 31 December 1996 (NODC Accession 0000462)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical, nutrients, and other data were collected from CTD, MBT, XBT, and bottle casts from the Indian Ocean. Data were collected from 01 January 1976 to 31...

  12. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 01 January 2001 to 31 December 2001 (NODC Accession 0000738)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 01 January 2001 to 31 December 2001. Data were submitted by the...

  13. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 01 January 2000 to 31 December 2000 (NODC Accession 0000584)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 01 January 2000 to 31 December 2000. Data were submitted by the...

  14. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 31 December 1993 to 07 January 1994 (NODC Accession 0000750)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 31 December 1993 to 07 January 1994. Data were submitted by the...

  15. Ammolagena clavata (Jones and Parker, 1860), an agglutinated benthic foraminiferal species - first report from the Recent sediments, Arabian Sea, Indian Ocean region

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Mazumder, A.; Saraswat, R.

    The rare presence of the agglutinated foraminiferal species Ammolagena clavata is presented for the first time from the Recent sediments of the Indian Ocean region. This species has previously been reported in Recent sediments from all other oceans...

  16. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 31 July 1991 to 20 August 1991 (NODC Accession 0000749)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 31 July 1991 to 20 August 1991. Data were submitted by the Commonwealth...

  17. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 31 December 1989 to 31 July 1990 (NODC Accession 0000748)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 31 December 1989 to 31 July 1990. Data were submitted by the Commonwealth...

  18. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 01 January 2002 to 31 December 2002 (NODC Accession 0000869)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 01 January 2002 to 31 December 2002. Data were submitted by the...

  19. Indian Ocean Near Real-Time Temperature Profile Data from the GTSPP project from 28 September 1998 to 02 October 1998 (NODC Accession 0000583)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical data were collected from XBT casts from the Indian Ocean. Data were collected from 28 September 1998 to 02 October 1998. Data were submitted by the Atlantic...

  20. Temperature profile data from EBT casts in the Indian Ocean from 13 February 1986 to 01 January 1989 (NODC Accession 0000210)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected using EBT casts in the Indian Ocean from the MYS OSTROVSKOGO, IGNAT PAVLYUCHENKOV, ZVEZDA AZOVA, and KARA-DAG from February...

  1. Oceanographic profile temperature, salinity and pressure measurements collected using moored buoy in the Indian Ocean from 2001-2006 (NODC Accession 0002733)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature and salinity measurements in the Equatorial Indian from 2001 to 2006 from the TRITON (TRIANGLE TRANS-OCEAN BUOY NETWORK); JAPAN AGENCY FOR MARINE-EARTH...

  2. Temperature, salinity, and other data from CTD casts in the Indian Ocean and other locations from 19890901 to 19910831 (NODC Accession 9700263)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature, salinity, and other data were collected from CTD casts in the Mediterranean Sea, Indian Ocean, and other locations from 01 September 1989 to 31 August...

  3. Controls on ferromanganese crust composition and reconnaissance resource potential, Ninetyeast Ridge, Indian Ocean

    Science.gov (United States)

    Hein, James; Conrad, Tracey A.; Mizell, Kira; Banakar, Virupaxa K.; Frey, Frederick A.; Sager, William W.

    2016-01-01

    A reconnaissance survey of Fe-Mn crusts from the 5000 km long (~31°S to 10°N) Ninetyeast Ridge (NER) in the Indian Ocean shows their widespread occurrence along the ridge as well as with water depth on the ridge flanks. The crusts are hydrogenetic based in growth rates and discrimination plots. Twenty samples from 12 crusts from 9 locations along the ridge were analyzed for chemical and mineralogical compositions, growth rates, and statistical relationships (Q-mode factor analysis, correlation coefficients) were calculated. The crusts collected are relatively thin (maximum 40 mm), and those analyzed varied from 4 mm to 32 mm. However, crusts as thick as 80 mm can be expected to occur based on the age of rocks that comprise the NER and the growth rates calculated here. Growth rates of the crusts increase to the north along the NER and with water depth. The increase to the north resulted from an increased supply of Mn from the oxygen minimum zone (OMZ) to depths below the OMZ combined with an increased supply of Fe at depth from the dissolution of biogenic carbonate and from deep-sourced hydrothermal Fe. These increased supplies of Fe increased growth rates of the deeper-water crusts along the entire NER. Because of the huge terrigenous (rivers, eolian, pyroclastic) and hydrothermal (three spreading centers) inputs to the Indian Ocean, and the history of primary productivity, Fe-Mn crust compositions vary from those analyzed from open-ocean locations in the Pacific.

  4. Search strategy in a complex and dynamic environment (the Indian Ocean case)

    Science.gov (United States)

    Loire, Sophie; Arbabi, Hassan; Clary, Patrick; Ivic, Stefan; Crnjaric-Zic, Nelida; Macesic, Senka; Crnkovic, Bojan; Mezic, Igor; UCSB Team; Rijeka Team

    2014-11-01

    The disappearance of Malaysia Airlines Flight 370 (MH370) in the early morning hours of 8 March 2014 has exposed the disconcerting lack of efficient methods for identifying where to look and how to look for missing objects in a complex and dynamic environment. The search area for plane debris is a remote part of the Indian Ocean. Searches, of the lawnmower type, have been unsuccessful so far. Lagrangian kinematics of mesoscale features are visible in hypergraph maps of the Indian Ocean surface currents. Without a precise knowledge of the crash site, these maps give an estimate of the time evolution of any initial distribution of plane debris and permits the design of a search strategy. The Dynamic Spectral Multiscale Coverage search algorithm is modified to search a spatial distribution of targets that is evolving with time following the dynamic of ocean surface currents. Trajectories are generated for multiple search agents such that their spatial coverage converges to the target distribution. Central to this DSMC algorithm is a metric for the ergodicity.

  5. Seafloor age dependence of Rayleigh wave phase velocities in the Indian Ocean

    Science.gov (United States)

    Godfrey, Karen E.; Dalton, Colleen A.; Ritsema, Jeroen

    2017-05-01

    Variations in the phase velocity of fundamental-mode Rayleigh waves across the Indian Ocean are determined using two inversion approaches. First, variations in phase velocity as a function of seafloor age are estimated using a pure-path age-dependent inversion method. Second, a two-dimensional parameterization is used to solve for phase velocity within 1.25° × 1.25° grid cells. Rayleigh wave travel time delays have been measured between periods of 38 and 200 s. The number of measurements in the study area ranges between 4139 paths at a period of 200 s and 22,272 paths at a period of 40 s. At periods Rodriguez Triple Junction and the Australian-Antarctic Discordance and anomalously low velocities immediately to the west of the Central Indian Ridge.

  6. Dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from POLARSTERN in the Indian Ocean, South Atlantic Ocean and Southern Oceans from 2002-11-24 to 2003-01-23 (NODC Accession 0108068)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0108068 includes chemical, discrete sample, physical and profile data collected from POLARSTERN in the Indian Ocean, South Atlantic Ocean and Southern...

  7. Dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the Hakuho Maru in the Indian Ocean, North Pacific Ocean and South Pacific Ocean from 2001-12-08 to 2002-01-19 (NODC Accession 0112347)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112347 includes biological, chemical, discrete sample, physical and profile data collected from Hakuho Maru in the Indian Ocean, North Pacific Ocean...

  8. Dissolved inorganic carbon, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the Hakuho Maru in the Indian Ocean, North Pacific Ocean and South Pacific Ocean from 2001-12-08 to 2002-01-19 (NODC Accession 0113547)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113547 includes biological, chemical, discrete sample, physical and profile data collected from Hakuho Maru in the Indian Ocean, North Pacific Ocean...

  9. The Evolution of Indian and Pacific Ocean Denitrification and Nitrogen Dynamcs since the Miocene

    Science.gov (United States)

    Ravelo, A. C.; Carney, C.; Rosenthal, Y.; Holbourn, A.; Kulhanek, D. K.

    2017-12-01

    The feedbacks between geochemical cycles and physical climate change are poorly understood; however, there has been tremendous progress in developing coupled models to help predict the direction and strength of these feedbacks. As such, there is a need for more data to validate and test these models. To this end, the nitrogen (N) cycle, and its links to the biological pump and to climate, is an active area of paleoceanographic research. Using N isotope records, Robinson et al. (2014) showed that pelagic denitrification in the Indian and Pacific Oceans intensified as climate cooled and subsurface ventilation decreased since the Pliocene. They pointed out that a more ventilated warm Pliocene contrasts with glacial-interglacial patterns wherein more ventilation occurs during cold phases, indicating that different mechanisms may occur at different timescales. Our objective is to better understand the nature of the feedbacks between the oceanic N cycle and climate by focusing on the large dynamic range of conditions that occurred during and since the Miocene. We used new cores drilled during IODP Expedition 363 to generate bulk sediment N isotope records at three western tropical Pacific sites (U1486, U1488, U1490) and one southeastern tropical Indian Ocean site (U1482). We find that the N isotope trends since the Pliocene are in agreement with previous studies showing increasing denitrification as climate cooled. In the Miocene, the Indian Ocean record shows no long-term N isotope trend whereas the Pacific Ocean records show a trend that is roughly coupled to changes in global climate suggesting that pelagic denitrification in the Pacific was strongly influenced by greater ventilation during global warmth. However, there are notable deviations from this coupling during several intervals in the Miocene, and there are site-to-site differences in trends. These deviations and differences can be explained by changes in tropical productivity (e.g., late Miocene biogenic

  10. Intraseasonal sea surface warming in the western Indian Ocean by oceanic equatorial Rossby waves

    Science.gov (United States)

    2017-05-09

    USA, 2Naval Research Laboratory, Ocean Dynamics and Prediction Branch, Stennis Space Center, Hancock County, Mississippi, USA, 3Department of Physics ...IO and predominantly located south of the equator. The intraseasonal currents associated with downwelling ER waves act on the temperature gradient to...yield warm anomalies in the western IO, even in the presence of cooling by surface fluxes. The SST gradient is unique to the western IO and likely

  11. Meridional overturning and large-scale circulation of the Indian Ocean

    Science.gov (United States)

    Ganachaud, Alexandre; Wunsch, Carl; Marotzke, Jochem; Toole, John

    2000-11-01

    The large scale Indian Ocean circulation is estimated from a global hydrographic inverse geostrophic box model with a focus on the meridional overturning circulation (MOC). The global model is based on selected recent World Ocean Circulation Experiment (WOCE) sections which in the Indian Basin consist of zonal sections at 32°S, 20°S and 8°S, and a section between Bali and Australia from the Java-Australia Dynamic Experiment (JADE). The circulation is required to conserve mass, salinity, heat, silica and "PO" (170PO4+O2). Near-conservation is imposed within layers bounded by neutral surfaces, while permitting advective and diffusive exchanges between the layers. Conceptually, the derived circulation is an estimate of the average circulation for the period 1987-1995. A deep inflow into the Indian Basin of 11±4 Sv is found, which is in the lower range of previous estimates, but consistent with conservation requirements and the global data set. The Indonesian Throughflow (ITF) is estimated at 15±5 Sv. The flow in the Mozambique Channel is of the same magnitude, implying a weak net flow between Madagascar and Australia. A net evaporation of -0.6±0.4 Sv is found between 32°S and 8°S, consistent with independent estimates. No net heat gain is found over the Indian Basin (0.1 ± 0.2PW north of 32°S) as a consequence of the large warm water influx from the ITF. Through the use of anomaly equations, the average dianeutral upwelling and diffusion between the sections are required and resolved, with values in the range 1-3×10-5 cm s-1 for the upwelling and 2-10 cm2 s-1 for the diffusivity.

  12. The Indonesian Throughflow (ITF) and its impacts on the Indian Ocean during the global warming slowdown period

    Science.gov (United States)

    Makarim, S.; Liu, Z.; Yu, W.; Yan, X.; Sprintall, J.

    2016-12-01

    The global warming slowdown indicated by a slower warming rate at the surface layer accompanied by stronger heat transport into the deeper layers has been explored in the Indian Ocean. Although the mechanisms of the global warming slowdown are still under warm debate, some clues have been recognized that decadal La Nina like-pattern induced decadal cooling in the Pacific Ocean and generated an increase of the Indonesian Throughflow (ITF) transport in 2004-2010. However, how the ITF spreading to the interior of the Indian Ocean and the impact of ITF changes on the Indian Ocean, in particular its water mass transformation and current system are still unknown. To this end, we analyzed thermohaline structure and current system at different depths in the Indian Ocean both during and just before the global warming slowdown period using the ORAS4 and ARGO dataset. Here, we found the new edge of ITF at off Sumatra presumably as northward deflection of ITF Lombok Strait, and The Monsoon Onset Monitoring and Social Ecology Impact (MOMSEI) and Java Upwelling Variation Observation (JUVO) dataset confirmed this evident. An isopycnal mixing method initially proposed by Du et al. (2013) is adopted to quantify the spreading of ITF water in the Indian Ocean, and therefore the impacts of ITF changes on the variation of the Agulhas Current, Leuween Current, Bay of Bengal Water. This study also prevailed the fresher salinity in the Indian Ocean during the slowdown warming period were not only contributed by stronger transport of the ITF, but also by freshening Arabian Sea and infiltrating Antartic Intermediate Water (AAIW).

  13. Phylogeography of Indo-Pacific reef fishes: sister wrassesCoris gaimardandC. cuvieriin the Red Sea, Indian Ocean and Pacific Ocean

    KAUST Repository

    Ahti, Pauliina A.

    2016-02-01

    Aim: The aim of this study was to resolve the evolutionary history, biogeographical barriers and population histories for sister species of wrasses, the African Coris (Coris cuvieri) in the Indian Ocean and Red Sea, and the Yellowtail Coris (Coris gaimard) in the Pacific Ocean. Glacial sea level fluctuations during the Pleistocene have shaped the evolutionary trajectories of Indo-Pacific marine fauna, primarily by creating barriers between the Red Sea, Indian Ocean and Pacific Ocean. Here, we evaluate the influence of these episodic glacial barriers on sister species C. cuvieri and C. gaimard. Location: Red Sea, Indian Ocean, Pacific Ocean. Methods: Sequences from mitochondrial DNA cytochrome oxidase c subunit I (COI), and nuclear introns gonadotropin-releasing hormone (GnRH) and ribosomal S7 protein were analysed in 426 individuals from across the range of both species. Median-joining networks, analysis of molecular variance and Bayesian estimates of the time since most recent common ancestor were used to resolve recent population history and connectivity. Results: Cytochrome oxidase c subunit I haplotypes showed a divergence of 0.97% between species, and nuclear alleles were shared between species. No population structure was detected between the Indian Ocean and Red Sea. The strongest signal of population structure was in C. gaimard between the Hawaiian biogeographical province and other Pacific locations (COI ϕ(symbol)ST = 0.040-0.173, P < 0.006; S7 ϕ(symbol)ST = 0.046, P < 0.001; GnRH ϕ(symbol)ST = 0.022, P < 0.005). Time to most recent common ancestor is c. 2.12 Ma for C. cuvieri and 1.76 Ma for C. gaimard. Main conclusions: We demonstrate an Indian-Pacific divergence of c. 2 Myr and high contemporary gene flow between the Red Sea and Indian Ocean, mediated in part by the long pelagic larval stage. The discovery of hybrids at Christmas Island indicates that Indian and Pacific lineages have come into secondary contact after allopatric isolation. Subspecies

  14. Phylogeography of Indo-Pacific reef fishes: sister wrassesCoris gaimardandC. cuvieriin the Red Sea, Indian Ocean and Pacific Ocean

    KAUST Repository

    Ahti, Pauliina A.; Coleman, Richard R.; DiBattista, Joseph; Berumen, Michael L.; Rocha, Luiz A.; Bowen, Brian W.

    2016-01-01

    Aim: The aim of this study was to resolve the evolutionary history, biogeographical barriers and population histories for sister species of wrasses, the African Coris (Coris cuvieri) in the Indian Ocean and Red Sea, and the Yellowtail Coris (Coris gaimard) in the Pacific Ocean. Glacial sea level fluctuations during the Pleistocene have shaped the evolutionary trajectories of Indo-Pacific marine fauna, primarily by creating barriers between the Red Sea, Indian Ocean and Pacific Ocean. Here, we evaluate the influence of these episodic glacial barriers on sister species C. cuvieri and C. gaimard. Location: Red Sea, Indian Ocean, Pacific Ocean. Methods: Sequences from mitochondrial DNA cytochrome oxidase c subunit I (COI), and nuclear introns gonadotropin-releasing hormone (GnRH) and ribosomal S7 protein were analysed in 426 individuals from across the range of both species. Median-joining networks, analysis of molecular variance and Bayesian estimates of the time since most recent common ancestor were used to resolve recent population history and connectivity. Results: Cytochrome oxidase c subunit I haplotypes showed a divergence of 0.97% between species, and nuclear alleles were shared between species. No population structure was detected between the Indian Ocean and Red Sea. The strongest signal of population structure was in C. gaimard between the Hawaiian biogeographical province and other Pacific locations (COI ϕ(symbol)ST = 0.040-0.173, P < 0.006; S7 ϕ(symbol)ST = 0.046, P < 0.001; GnRH ϕ(symbol)ST = 0.022, P < 0.005). Time to most recent common ancestor is c. 2.12 Ma for C. cuvieri and 1.76 Ma for C. gaimard. Main conclusions: We demonstrate an Indian-Pacific divergence of c. 2 Myr and high contemporary gene flow between the Red Sea and Indian Ocean, mediated in part by the long pelagic larval stage. The discovery of hybrids at Christmas Island indicates that Indian and Pacific lineages have come into secondary contact after allopatric isolation. Subspecies

  15. Towards a merged satellite and in situ fluorescence ocean chlorophyll product

    Directory of Open Access Journals (Sweden)

    H. Lavigne

    2012-06-01

    Full Text Available Understanding the ocean carbon cycle requires a precise assessment of phytoplankton biomass in the oceans. In terms of numbers of observations, satellite data represent the largest available data set. However, as they are limited to surface waters, they have to be merged with in situ observations. Amongst the in situ data, fluorescence profiles constitute the greatest data set available, because fluorometers have operated routinely on oceanographic cruises since the 1970s. Nevertheless, fluorescence is only a proxy of the total chlorophyll a concentration and a data calibration is required. Calibration issues are, however, sources of uncertainty, and they have prevented a systematic and wide range exploitation of the fluorescence data set. In particular, very few attempts to standardize the fluorescence databases have been made. Consequently, merged estimations with other data sources (e.g. satellite are lacking.

    We propose a merging method to fill this gap. It consists firstly in adjusting the fluorescence profile to impose a zero chlorophyll a concentration at depth. Secondly, each point of the fluorescence profile is then multiplied by a correction coefficient, which forces the chlorophyll a integrated content measured on the fluorescence profile to be consistent with the concomitant ocean colour observation. The method is close to the approach proposed by Boss et al. (2008 to correct fluorescence data of a profiling float, although important differences do exist. To develop and test our approach, in situ data from three open ocean stations (BATS, HOT and DYFAMED were used. Comparison of the so-called "satellite-corrected" fluorescence profiles with concomitant bottle-derived estimations of chlorophyll a concentration was performed to evaluate the final error (estimated at 31%. Comparison with the Boss et al. (2008 method, using a subset of the DYFAMED data set, demonstrated that the methods have similar

  16. Sac-D Aquarius a Satellite for Ocean, Climate and Environment. One Year of Data

    Science.gov (United States)

    Torrusio, S.; Lagerloef, G.; Rabolli, M.; LeVine, D.

    2012-07-01

    The SAC-D/Aquarius satellite was launched in June 10, 2011. It's a joint mission between Argentina (through CONAE) and US (NASA). This satellite is a true Observatory with a suite of sensors for Earth Observation, its weight is 1400 kg, sun-synchronous orbit at 657 km (6 pm ascendant node), revisit of seven days. Other space agencies have contributed with instruments and support (facilities and ground segment), as CNES, CSI, ASI and AEB/INPE. The primary objective is to monitor global variations in ocean surface salinity (SSS) in order to improve the knowledge about ocean circulation, water cycle and climate. The SSS is performed with Aquarius instrument (NASA). Other oceanic and atmospheric parameters are measured with a MWR, from CONAE, in K and Ka band, as wind speed, rain rate, sea ice, water vapour and liquid water in clouds. The thermal camera (NIRST) estimates sea surface temperature and detect high temperature events (fires and volcanic eruptions). The High Sensitivity Camera (HSC) generates night images (very useful for fishery activity monitoring in the sea, studying of electrical storms, polar auroras and urban application). The DCS (Data Collection System, from CONAE) can receive meteorological and environmental data from ground platforms and distribute among users. The TDP (Technological Demonstration Package, from CONAE) measures different parameters of satellite position and velocity. Other two important instruments are ROSA (from Italy) and CARMEN 1 (from France). The first is an atmospheric sounder, it allows elaborating atmospheric profiles of temperature, pressure and humidity, and the second has detectors for studies of space debris and the effects of radiation on electronic devices. This work provides a review of the first year of data, including the status of calibration and validation, other finding and at the same time we want to present the progress in the active educational and outreach program including the information of SAC-D Aquarius

  17. Specificity of Atmosphere Correction of Satellite Ocean Color Data in Far-Eastern Region

    Science.gov (United States)

    Trusenkova, O.; Kachur, V.; Aleksanin, A. I.

    2016-02-01

    It was carried out an error analysis of satellite reflectance coefficients (Rrs) of MODIS/AQUA colour data for two atmospheric correction algorithms (NIR, MUMM) in the Far-Eastern region. Some sets of unique data of in situ and satellite measurements have been analysed. A set has some measurements with ASD spectroradiometer for each satellite pass. The measurement allocations were selected so the Chlorophyll-a concentration has high variability. Analysis of arbitrary set demonstrated that the main error component is systematic error, and it has simple relations on Rrs values. The reasons of such error behavior are considered. The most probable explanation of the large errors of oceanic color parameters in the Far-Eastern region is the ability of high concentrations of continental aerosol. A comparison of satellite and in situ measurements at AERONET stations of USA and South Korea regions has been made. It was shown that for NIR-correction of the atmosphere influence the error values in these two regions have differences up to 10 times for almost the same water turbidity and relatively good accuracy of computation of aerosol optical thickness. The study was supported by grant Russian Scientific Foundation No. 14-50-00034, by grant of Russian Foundation of Basic Research No.15-35-21032-mol-a-ved, and by Program of Basic Research "Far East" of Far Eastern Branch of Russian Academy of Sciences.

  18. Atmospheric correction using near-infrared bands for satellite ocean color data processing in the turbid western Pacific region.

    Science.gov (United States)

    Wang, Menghua; Shi, Wei; Jiang, Lide

    2012-01-16

    A regional near-infrared (NIR) ocean normalized water-leaving radiance (nL(w)(λ)) model is proposed for atmospheric correction for ocean color data processing in the western Pacific region, including the Bohai Sea, Yellow Sea, and East China Sea. Our motivation for this work is to derive ocean color products in the highly turbid western Pacific region using the Geostationary Ocean Color Imager (GOCI) onboard South Korean Communication, Ocean, and Meteorological Satellite (COMS). GOCI has eight spectral bands from 412 to 865 nm but does not have shortwave infrared (SWIR) bands that are needed for satellite ocean color remote sensing in the turbid ocean region. Based on a regional empirical relationship between the NIR nL(w)(λ) and diffuse attenuation coefficient at 490 nm (K(d)(490)), which is derived from the long-term measurements with the Moderate-resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite, an iterative scheme with the NIR-based atmospheric correction algorithm has been developed. Results from MODIS-Aqua measurements show that ocean color products in the region derived from the new proposed NIR-corrected atmospheric correction algorithm match well with those from the SWIR atmospheric correction algorithm. Thus, the proposed new atmospheric correction method provides an alternative for ocean color data processing for GOCI (and other ocean color satellite sensors without SWIR bands) in the turbid ocean regions of the Bohai Sea, Yellow Sea, and East China Sea, although the SWIR-based atmospheric correction approach is still much preferred. The proposed atmospheric correction methodology can also be applied to other turbid coastal regions.

  19. Specificity of Atmospheric Correction of Satellite Data on Ocean Color in the Far East

    Science.gov (United States)

    Aleksanin, A. I.; Kachur, V. A.

    2017-12-01

    Calculation errors in ocean-brightness coefficients in the Far Eastern are analyzed for two atmospheric correction algorithms (NIR and MUMM). The daylight measurements in different water types show that the main error component is systematic and has a simple dependence on the magnitudes of the coefficients. The causes of the error behavior are considered. The most probable explanation for the large errors in ocean-color parameters in the Far East is a high concentration of continental aerosol absorbing light. A comparison between satellite and in situ measurements at AERONET stations in the United States and South Korea has been made. It is shown the errors in these two regions differ by up to 10 times upon close water turbidity and relatively high aerosol optical-depth computation precision in the case of using the NIR correction of the atmospheric effect.

  20. Lunar tidal acceleration obtained from satellite-derived ocean tide parameters

    Science.gov (United States)

    Goad, C. C.; Douglas, B. C.

    1978-01-01

    One hundred sets of mean elements of GEOS-3 computed at 2-day intervals yielded observation equations for the M sub 2 ocean tide from the long periodic variations of the inclination and node of the orbit. The 2nd degree Love number was given the value k sub 2 = 0.30 and the solid tide phase angle was taken to be zero. Combining obtained equations with results for the satellite 1967-92A gives the M sub 2 ocean tide parameter values. Under the same assumption of zero solid tide phase lag, the lunar tidal acceleration was found mostly due to the C sub 22 term in the expansion of the M sub 2 tide with additional small contributions from the 0 sub 1 and N sub 2 tides. Using Lambeck's (1975) estimates for the latter, the obtained acceleration in lunar longitudal in excellent agreement with the most recent determinations from ancient and modern astronomical data.