scholarly journals Seasonal variability of salt transport during the Indian Ocean monsoons

2011 ◽  
Vol 116 (C8) ◽  
Author(s):  
Ebenezer S. Nyadjro ◽  
Bulusu Subrahmanyam ◽  
Jay F. Shriver
Keyword(s):  
Indian Ocean ◽  
Seasonal Variability ◽  
Salt Transport ◽  
The Indian Ocean

Generation and seasonal variability of eddy kinetic energy in the central Indian Ocean

2021 ◽  
Author(s):  
Georgy I. Shapiro ◽  
Jose Maria Gonzalez-Ondina
Keyword(s):  
Indian Ocean ◽  
Kinetic Energy ◽  
Seasonal Variability ◽  
Open Ocean ◽  
Eddy Kinetic Energy ◽  
Horizontal Shear ◽  
Data Set ◽  
Central Indian Ocean ◽  
The Indian Ocean ◽  
Meso Scale

<p>The breakthrough in our knowledge of ocean eddies came with the results of the POLYGON-67 experiment in the central Indian Ocean carried out in January-April 1967 (see Koshlyakov et al, 2016). It was the first direct and unambiguous observation that proved an earlier hypothesis by V. B. Shtockman of the existence of mesoscale eddies in open ocean, not only next to strong jet-stream currents. Now it is well known that the currents in open ocean are almost everywhere dominated by meso-scale eddies also known as synoptic eddies (Robinson, 1983). POLYGON-67 experiment covered a rectangle bounded by 10-15°N and 63-66.5°E. The purpose of this work is to analyse the seasonal variability of meso-scale eddy activity in the area covered by POLYGON-67 using a modern and comprehensive data set produced by an operational data assimilation model over a period from 1998 to 2017.</p><p>The 20-year long eddy resolving reanalysis of velocity fields in the Indian Ocean allows the study of seasonal variability, dynamics and generating mechanisms of eddy kinetic energy (EKE) in the tropical Indian Ocean, including the area covered by the original survey of POLYGON-67. In contrast to some other areas of the World Ocean, the EKE seasonality shows two maxima, the large one in April and the secondary one in October. The main mechanism of EKE generation is the barotropic instability which is evidenced by high correlation between EKE and enstrophy of large-scale currents, representing the strength of horizontal shear. It is found that the main contributor to the EKE variability within POLYGON-67 area is the advection of EKE across the boundaries during January-October, while the local generation has a comparable magnitude during August-December. The direction and strength of surface currents is consistent with the monsoon wind pattern in the area.</p><p>References</p><p>Koshlyakov, M.N., Morozov, E.G., and Neiman, V.G., 2016. Historical findings of the Russian physical oceanographers in the Indian Ocean. Geoscience Letters, 3:19; doi:10.1186/s40562-016-0051-6</p><p>Robinson, A.R. (Ed), 1983. Eddies in Marine Science. Springer, ISBN 978-3-642-69003-7, 612p.</p>

Seasonal Variability of Salinity and Salt Transport in the Northern Indian Ocean

2015 ◽  
Vol 45 (7) ◽  
pp. 1947-1966 ◽  
Author(s):  
Joseph M. D’Addezio ◽  
Bulusu Subrahmanyam ◽  
Ebenezer S. Nyadjro ◽  
V. S. N. Murty
Keyword(s):  
Indian Ocean ◽  
Seasonal Variability ◽  
Ocean Model ◽  
Salt Transport ◽  
Sea Surface Salinity ◽  
Northern Indian Ocean ◽  
Surface Salinity ◽  
Ocean Reanalysis ◽  
Model Simulations ◽  
Ocean Data Assimilation

AbstractAnalyses using a suite of observational datasets (Aquarius and Argo) and model simulations are carried out to examine the seasonal variability of salinity in the northern Indian Ocean (NIO). The model simulations include Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2), the European Centre for Medium-Range Weather Forecasts–Ocean Reanalysis System 4 (ECMWF–ORAS4), Simple Ocean Data Assimilation (SODA) reanalysis, and the Hybrid Coordinate Ocean Model (HYCOM). The 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 semiannual monsoons. Aquarius proves a useful tool for observing this dynamic region and reveals some aspects of sea surface salinity (SSS) variability that Argo cannot resolve. The study revealed large disagreement between surface salt transports derived from observed- and analysis-derived salinity fields. Although differences in SSS between the observations and the model solutions are small, model simulations provide much greater spatial variability of surface salt transports due to finer detailed current structure. Meridional depth-integrated salt transports along 6°N revealed dominant advective processes from the surface toward near-bottom depths. In the Arabian Sea (Bay of Bengal), the net monthly mean maximum northward (southward) salt transport of ~50 × 106 kg s −1 occurs in July, and annual-mean salt transports across this section are about −2.5 × 106 kg s −1 (3 × 106 kg s −1).

scholarly journals Intermediate-Depth Circulation of the Indian and South Pacific Oceans Measured by Autonomous Floats

2005 ◽  
Vol 35 (5) ◽  
pp. 683-707 ◽  
Author(s):  
Russ E. Davis
Keyword(s):  
Indian Ocean ◽  
Seasonal Variability ◽  
World Ocean ◽  
South Pacific ◽  
Western Boundary ◽  
Mean Flow ◽  
The North ◽  
The Indian Ocean ◽  
The Mean ◽  
Mean Circulation

Abstract As part of the World Ocean Circulation Experiment, 306 autonomous floats were deployed in the tropical and South Pacific Ocean and 228 were deployed in the Indian Ocean to observe the basinwide circulation near 900-m depth. Mean velocities, seasonal variability, and lateral eddy diffusivity from the resultant 2583 float-years of data are presented. Area averages, local function fits, and a novel application of objective mapping are used to estimate the mean circulation. Patterns of mean circulation resemble those at the surface in both basins. Well-developed subtropical gyres, twice as strong in the Indian Ocean as in the Pacific, feed western boundary currents. Tropical gyres are separated by eastward flow along the equator in both hemispheres of both basins, although the Indian subcontinent splits the north Indian tropical gyre. The Antarctic Circumpolar Current (ACC) and west wind drifts are prominent in both basins, generally tending slightly southward but deviating to the north behind the Del Cano, Kerguelen, and Campbell Plateaus and, of course, South America. Remarkably, the eastern boundaries of the southern subtropical gyres in all three basins apparently occur in the ocean interior, away from land. The Indian Ocean’s subtropical gyre, and perhaps part of the South Atlantic’s, reaches east to a retroflection just upstream of the Campbell Plateau south of New Zealand. Seasonal variability at 900 m is focused around the equator with weaker variability found near certain bathymetric features. There is a remarkable agreement between the observed seasonable variability and that predicted by the Jet Propulsion Laboratory (JPL)–Estimating the Circulation and Climate of the Ocean (ECCO) data-assimilating numerical model. Aside from seasonal effects, eddy variability is greatest along the equator, in tropical and subtropical western basins, and along the ACC. Integrals of velocity across regional passages (Tasman Sea, Mozambique Channel) provide useful reference for hydrographic analyses of transport. Across whole ocean basins, however, the uncertainty associated with the appropriate continuity relation for horizontal flow (e.g., geostrophy vs nondivergence) is comparable to the mean flow.

scholarly journals Mechanisms of Mixed-Layer Salinity Seasonal Variability in the Indian Ocean

2018 ◽  
Vol 123 (1) ◽  
pp. 466-496 ◽  
Author(s):  
Julia Köhler ◽  
Nuno Serra ◽  
Frank O. Bryan ◽  
Benjamin K. Johnson ◽  
Detlef Stammer
Keyword(s):  
Indian Ocean ◽  
Mixed Layer ◽  
Seasonal Variability ◽  
The Indian Ocean
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