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Author Nyadjro, E.S. ; Rydbeck, A.V. ; Jensen, T.G. ; Richman, J.G. ; Shriver, J.F.
Title On the Generation and Salinity Impacts of Intraseasonal Westward Jets in the Equatorial Indian Ocean Type $loc['typeJournal Article']
Year 2020 Publication Journal of Geophysical Research: Oceans Abbreviated Journal J. Geophys. Res. Oceans
Volume 125
Issue 6
Pages e2020JC016066
Keywords ndian Ocean ; intraseasonal variability ; westward Jet ; intraseasonal oscillations ; mixed layer salinity ; surface currents
Abstract While westerly winds dominate the equatorial Indian Ocean and generate the well‐known eastward flowing Wyrtki Jets during boreal spring and fall, there is evidence of a strong westward surface jet during winter that is swifter than eastward currents during that season. A weaker westward jet is found in summer. In this study, we report the occurrence, characteristics, and intraseasonal variability of this westward jet and its impact on mixed layer salinity in the equatorial Indian Ocean using the HYbrid Coordinate Ocean Model (HYCOM) reanalysis with the Navy Coupled Ocean Data Assimilation (NCODA). The westward jet typically occurs in the upper 50 m, above an eastward flowing equatorial undercurrent, with peak westward volume transport of approximately −8 Sv. The westward jet builds up gradually, decays rapidly, and is primarily forced by local intraseasonal wind stress anomalies generated by atmospheric intraseasonal convection. Westward acceleration of the jet occurs when the dominant intraseasonal westward wind anomaly is not balanced by the zonal pressure gradient (ZPG) force. The intraseasonal westward jet generates strong horizontal advection and is the leading cause of mixed layer freshening in the western equatorial Indian Ocean. Without it, a saltier mixed layer would persist and weaken any barrier layers. Existing barrier layers are strengthened following the passage of freshwater‐laden westward jets. Deceleration of the westward jet occurs when the eastward ZPG becomes increasingly important and the westward intraseasonal wind anomalies weaken. A rapid reversal of atmospheric intraseasonal convection‐driven surface winds eventually terminates the westward jet.
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ISSN 2169-9275
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Call Number COAPS @ user @
Serial 1118
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Author Podestá, G. ; Letson, D. ; Messina, C. ; Royce, F. ; Ferreyra, R.A. ; Jones, J. ; Hansen, J. ; Llovet, I. ; Grondona, M. ; O'Brien, J.J.
Title Use of ENSO-related climate information in agricultural decision making in Argentina: a pilot experience Type $loc['typeJournal Article']
Year 2002 Publication Agricultural Systems Abbreviated Journal Agricultural Systems
Volume 74
Issue 3
Pages 371-392
Keywords El Nino-Southern Oscillation ; argentine pampas ; climate forecasts ; climate-adaptive management ; linked modeling
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ISSN 0308521X
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Call Number COAPS @ mfield @
Serial 491
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Author Shinoda, T. ; Han, W. ; Zamudio, L. ; Lien, R.-C. ; Katsumata, M.
Title Remote Ocean Response to the Madden-Julian Oscillation during the DYNAMO Field Campaign: Impact on Somali Current System and the Seychelles-Chagos Thermocline Ridge Type $loc['typeJournal Article']
Year 2017 Publication Atmosphere Abbreviated Journal Atmosphere
Volume 8
Issue 9
Pages 171
Keywords Madden-Julian oscillation ; CINDY/DYNAMO ; Somali current ; Indian Ocean
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ISSN 2073-4433
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Call Number COAPS @ mfield @
Serial 282
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Author Steffen, J. ; Bourassa, M.
Title Barrier Layer Development Local to Tropical Cyclones based on Argo Float Observations Type $loc['typeJournal Article']
Year 2018 Publication Journal of Physical Oceanography Abbreviated Journal J. Phys. Oceanogr.
Volume 48
Issue 9
Pages 1951-1968
Keywords SEA-SURFACE TEMPERATURE ; UPPER-OCEAN RESPONSE ; NINO SOUTHERN-OSCILLATION ; MIXED-LAYER ; INDIAN-OCEAN ; HEAT-BUDGET ; NUMERICAL SIMULATIONS ; HURRICANES ; VARIABILITY ; PACIFIC
Abstract The objective of this study is to quantify barrier layer development due to tropical cyclone (TC) passage using Argo float observations of temperature and salinity. To accomplish this objective, a climatology of Argo float measurements is developed from 2001 to 2014 for the Atlantic, eastern Pacific, and central Pacific basins. Each Argo float sample consists of a prestorm and poststorm temperature and salinity profile pair. In addition, a no-TC Argo pair dataset is derived for comparison to account for natural ocean state variability and instrument sensitivity. The Atlantic basin shows a statistically significant increase in barrier layer thickness (BLT) and barrier layer potential energy (BLPE) that is largely attributable to an increase of 2.6 m in the post-TC isothermal layer depth (ITLD). The eastern Pacific basin shows no significant changes to any barrier layer characteristic, likely due to a shallow and highly stratified pycnocline. However, the near-surface layer freshens in the upper 30 m after TC passage, which increases static stability. Finally, the central Pacific has a statistically significant freshening in the upper 20-30 m that increases upper-ocean stratification by similar to 35%. The mechanisms responsible for increases in BLPE vary between the Atlantic and both Pacific basins; the Atlantic is sensitive to ITLD deepening, while the Pacific basins show near-surface freshening to be more important in barrier layer development. In addition, Argo data subsets are used to investigate the physical relationships between the barrier layer and TC intensity, TC translation speed, radial distance from TC center, and time after TC passage.
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ISSN 0022-3670
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Call Number COAPS @ user @
Serial 970
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