Altimetric Observations and Model Simulations of Coastal Kelvin Waves in the Bay of Bengal

Nienhaus, M. J.; Subrahmanyam, Bulusu; Murty, V. S. N.

doi:10.1080/01490419.2012.718607

Cited by 31 publications

(35 citation statements)

References 29 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Their study shows that remote forcing from the equatorial Indian Ocean plays a predominant role than the local wind forcing to determine the mean coastal circulation within the AS and around the islands. Their results are consistent with earlier modeling studies in the AS (Nienhaus et al, ; Potemra et al, ). Recently, Chandran et al () used the data from two hydrographic cruises (January 2009 and November–December 2011) to document the circulation and biogeochemical variability in the AS during the winter monsoon.…”

Section: Introductionsupporting

confidence: 93%

Observed Upper Ocean Seasonal and Intraseasonal Variability in the Andaman Sea

et al. 2019

View full text Add to dashboard Cite

The observed seasonal and intraseasonal evolution of near‐surface meteorological and oceanographic variables in the Andaman Sea for the period March 2014 to December 2017 are examined using moored buoy observations at 10.5°N, 94°E. The amplitude of temperature inversions is very weak (0.2 to 0.4 °C), and they appeared primarily during winter (November–January) and latter part of summer (May–August). The net surface heat flux plays a primary role, and vertical processes term contributes secondarily to determine the seasonal mixed layer (ML) heat storage variability. Consistent with the seasonal variations of formation and strength of temperature inversion, vertical processes term shows a positive tendency during winter. The sea surface salinity shows large amplitude intraseasonal variability during fall and winter, and it is attributed to the variability of horizontal circulation in the presence of large lateral sea surface salinity gradients at the mooring location. The sea surface temperature shows the presence of strong intraseasonal variability between 20 and 80 days, though its amplitude of oscillation is distinctly higher during May–October than November–April. Band‐pass filtered (20–80 days) time series of different components of the ML heat budget shows that the net surface heat flux primarily determines the intraseasonal ML heat storage variability. Our analysis further shows that during May–October, both net shortwave radiation and latent heat flux together determine the modulation of the intraseasonal net surface heat flux. In contrast, latent heat flux acts as the sole factor to determine the modulation of the intraseasonal net surface heat flux during November–April.

show abstract

Section: Introductionsupporting

confidence: 93%

Observed Upper Ocean Seasonal and Intraseasonal Variability in the Andaman Sea

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The surface winds and currents reverse between the northeast and southwest monsoon seasons and at the end of the southwest monsoon in October, the currents and winds once again reverse from southwesterly to northeasterly. This reversal of currents coincides with the arrival of the coastally trapped second downwelling Kelvin wave along the coast of India from the eastern boundary of the basin (Nienhaus et al, ). This coastal Kelvin wave in the Bay of Bengal helps to enhance the East India Coastal Current (EICC), transporting lower salinity waters from the Bay of Bengal from October through December.…”

Section: Introductionmentioning

confidence: 70%

The Role of Salinity in the Southeastern Arabian Sea in Determining Monsoon Onset and Strength

2020

Self Cite

View full text Add to dashboard Cite

In this study, we examine the role of freshwater transported from the Bay of Bengal into the southeastern Arabian Sea (SEAS) in determining both the timing of monsoon onset and the strength of the ensuing monsoon. To do this, we use a combination of satellite-derived salinity data and reanalysis products from 1980 to 2016 in order to discuss seasonal, interannual, subdecadal, and long-term decadal variability in various atmospheric and oceanic contributors such as ocean heat content, freshwater transport, ERA5 instantaneous moisture flux, mixed layer depth, and barrier layer thickness. The salt budget in the SEAS reveals the dominance of meridional freshwater advective transport that brings in variability in salinity and thus in salinity stratification, as well as in mixed layer processes. We find that these parameters exhibit the prevalence of a long-term decadal variability (with trends of increasing/decreasing phases over a 15-year duration) over which interannual (3-year trend) and intradecadal (7-year trend) variability trends are superimposed. The patterns of both the 3-and 7-year trends follow each other closely, and relatively high amplitudes are seen in the 3-year trends. The long-term decrease in moisture flux and freshwater transport into the SEAS along with a rise in ocean heat content over a 15-year duration after 1994 contributed to a lack of strong monsoons in recent years; the prevailing interannual and intradecadal variability in these parameters associated with the Indian Ocean Dipole and El Niño Southern Oscillation events favored weaker and normal monsoons after 1994. Plain Language SummaryThe timing and intensity of the southwest monsoon is difficult to forecast and has been the subject of a great deal of research. In particular, the genesis of a monsoon onset vortex over the southeastern Arabian Sea (SEAS) encompassing the Arabian Sea Mini Warm Pool has received increased attention for the role it plays on the onset of the southwest monsoon. In our study, we examine how the low salinity waters transported from the Bay of Bengal (both along the east coast of India and from the southern Bay of Bengal) into the SEAS region influence the strength and timing of the ensuing southwest monsoon. Our finding is that this low salinity water has a significant impact on barrier layer formation in the SEAS and the vertical thermal structure of the Arabian Sea Mini Warm Pool. Further examination of subdecadal, decadal, and long-period decadal trends from 1980 to 2016 shows that instantaneous moisture fluxes and zonal winds over the SEAS have decreased substantially, and barrier layer thickness has increased since 1994 in association with the increasing trend in ocean heat content and contributed to the lack of strong southwest monsoons after 1994.

show abstract

“…Prior to the summer monsoon (April), there are low SLA in the northern Bay and an observed zonal SLA gradient throughout the Bay, with higher SLA in the western Bay. The spatial distribution of high and low SLA has been identified as a response to coastally trapped Kelvin waves (Nienhaus et al ., ). These Kelvin waves trigger the initiation of westward‐propagating Rossby waves (Schott et al ., ).…”

Section: Resultsmentioning

confidence: 97%

Detection of intraseasonal oscillations in the Bay of Bengal using altimetry

Trott

Subrahmanyam

2019

Atmospheric Science Letters

View full text Add to dashboard Cite

Air-sea and mixed layer dynamics in the Bay of Bengal (BoB) respond strongly to Intraseasonal Oscillations (ISOs) that primarily operate on three observed time scales: the 30-90 day Madden-Julian Oscillation, the 10-20 day quasi-biweekly oscillation, and the synoptic-scale 3-7 day oscillation of the monsoon trough. In this research, we focus on local and basin-wide signals, zonal and meridional propagation, and variability of ISOs with respect to the strength of the summer monsoon season over a multi-decadal period . For the first time, this study examines the relationship between larger-and shorter-period ISOs in SLA and shows the usefulness of altimetry data in Indian monsoon studies. We compare ISOs in SLA during years with summer monsoons of varying strengths, finding notably stronger circulation and larger amplitude of all ISOs in years with stronger summer monsoons theorized in part to be due to the first-baroclinic mode forcing from low-level winds (R 2 values of 0.61, 0.67, and 0.64 in the northern, central, and southern Bay, respectively), although it is important to note the influence of other local forcings, such as mesoscale eddies and coastal Kelvin waves. We demonstrate that 30-90 day variability of SLA is initially forced by equatorial processes and strengthened by local processes in the BoB, as higher-amplitude SLA ISOs were consistently observed in the southern and eastern Bay. Local processes like coastal Kelvin waves were found to strongly influence the 10-20 day quasibiweekly signal, as was seen in the high-amplitude 10-20 day SLA ISOs found in the eastern BoB. The synoptic signal also revealed a zonal pattern consistent with coastal Kelvin wave intensification and eddy generation. K E Y W O R D S altimetry, Bay of Bengal, intraseasonal oscillations, Madden-Julian oscillation

show abstract

Altimetric Observations and Model Simulations of Coastal Kelvin Waves in the Bay of Bengal

Cited by 31 publications

References 29 publications

Observed Upper Ocean Seasonal and Intraseasonal Variability in the Andaman Sea

Observed Upper Ocean Seasonal and Intraseasonal Variability in the Andaman Sea

The Role of Salinity in the Southeastern Arabian Sea in Determining Monsoon Onset and Strength

Detection of intraseasonal oscillations in the Bay of Bengal using altimetry

Contact Info

Product

Resources

About