View on Bay of Bengal upwelling area on the basis of 19-years of satellite sea surface temperature

Krishna, K. Muni

doi:10.1080/17538940802149965

Cited by 14 publications

(9 citation statements)

References 9 publications

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“…Additional care was taken to use only grids (see Figure 1) at least 1 • away from the coast (especially Northern Bay). This was essential to remove any effect of current-induced SST changes close to the coast and avoid any false relationships that may arise due to coastal processes such as upwelling and freshwater flux that may change SSTs (Krishna, 2008). In addition, aerosol retrieval errors are significantly high closer to the coast due to the land-ocean boundary (different algorithms used for the AOD retrievals) and the potential effects of sediment concentrations on the overall surface-atmosphere reflectance errors in aerosol retrievals from satellite sensors (Anderson et al, 2013).…”

Section: Analysis Methodsmentioning

confidence: 99%

“…In addition, the highly dynamic nature and the role of multiple factors affecting SSTs make it difficult to explore these relationships, if any. Some of the factors affecting SSTs are solar insolation, warm/cold water advection, and other marine processes, namely ocean currents, upwelling/downwelling phenomena, and eddies (Leeuwenburgh and Stammer, 2001;Shinoda, 2005;Krishna, 2008;Mandal et al, 2019;Buckley et al, 2020). In addition, the BoB also receives a sizable freshwater influx from the rivers and undergoes near-surface ocean-atmosphere interactions, which alters the upper ocean processes (Parampil et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Aerosol Induced Changes in Sea Surface Temperature Over the Bay of Bengal Due to COVID-19 Lockdown

et al. 2021

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The role of COVID-19 pandemic lockdown in improving air quality was reported extensively for land regions globally. However, limited studies have explored these over oceanic areas close to high anthropogenic activities and emissions. The Bay of Bengal (BoB) basin is one such region adjacent to the highly populated South Asian region. We find that Aerosol Optical Depth (AOD) over the BoB declined by as much as 0.1 or 30% during the peak lockdown of April 2020 compared to long-term climatology during 2003–2019. Simultaneously, the sea surface temperature (SST) rose by 0.5–1.5°C over the central and north-western parts of the BoB with an average increase of 0.83°C. We show that up to 30% of this observed warming is attributable to reduced atmospheric aerosols. The study highlights the importance of anthropogenic emissions reduction due to COVID lockdown on short-term changes to SST over ocean basins with implications to regional weather.

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Section: Analysis Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aerosol Induced Changes in Sea Surface Temperature Over the Bay of Bengal Due to COVID-19 Lockdown

et al. 2021

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“…Similar observations of coastal upwelling were made by [7] along the stretch of the east coast of India from 16° 30' N to 18° 30' N in hydrographic data. Coastal upwelling signatures have also been identified along the stretch of the coast between Chennai (13.082 °N) and Vishakapatnam (17.687 °N) based on satellite SST data [8]. [9] has analysed the long-term variability of coastal upwelling along the eastern coast of south India using UISST and AWS; this closely resembles the methods adopted in the present analysis.…”

Section: Introductionmentioning

confidence: 95%

Coastal Upwelling in the Bay of Bengal: Role of Local and Remote Windstress

Ray¹,

Swain²,

Ali³

et al. 2022

Preprint

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Monsoon winds drive upwelling along the eastern coast of India during the south-west (SW) monsoons. These winds also provide alongshore windstress (AWS) resulting in positive cross-shore Ekman transport (ET) from late May to the end of September. While instances of high ET and sea surface temperature (SST) based upwelling index (UI_SST) were observed along different parts of the coast, UI_SST was weaker in the northern section in the earlier part of monsoon. This was even in the presence of maximum AWS and ET during the 10 years analysis period spanning January-2009 to December-2018. Additionally, negative sea surface height anomalies (SSHAs), typically associated with coastal upwelling, were observed only along the southern-most coast. An empirical orthogonal function (EOF) analysis revealed two coherent modes of SSHA variation. The first principal component (PC) showed a SSHA signature coincident spatio-temporally with the first downwelling Kelvin wave, closely associated with the equatorial zonal winds that drive coastal Kelvin waves. The third PC with a coastal SSHA pattern similar to the second upwelling Kelvin wave was associated with offshore ET along the northern part of the Indian east coast. Time series of the two PCs exhibited suppression of coastal upwelling by downwelling Kelvin waves during May-July along the northeastern coast of India. Local AWS driven ET was the primary driver of coastal upwelling with the weakening of the remotely forced Kelvin waves in August. A coherent mode consisting of negative coastal SSHA signature was excited in response to local AWS driven ET during the upwelling period. This study examined the spatio-temporal variability of SW monsoon coastal upwelling along the east coast of India and illustrated the role of equatorial windstress forced first downwelling Kelvin wave in suppressing upwelling in the northern part of the coast during early SW monsoon season.

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“…The central east coast of India is part of the East India coastal current system region, one of the world's most productive areas due to coastal upwelling phenomena (Divakar Naidu et al, 1999; Gomes et al, 2000;Kumar et al, 2004;Muni Krishna, 2007 and2008; Narasimha Rao, 2002;Rao, et al, 1995;Rao and Chamarthi, 1997;Smith, 1995). The interchange of waters between the coastal zone and the open sea is a crucial area of research for determining abiotic conditions of coastal ecosystem evolution.…”

Section: Introductionmentioning

confidence: 98%

Coastal upwelling activity along the central east coast of India

Krishna

2008

SPIE Proceedings

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High primary productivity along the central east coast of India is usually related to coastal upwelling activity that injects nutrients into the euphotic zone in response to prevailing longshore winds. The upwelling process has maximum intensity during March and August-September, with the coastal upwelling index varying from 10 to 150 m3/s per 100 m of coastline. Along the entire coast of the peninsula, the upwelling intensity changes in accordance with local wind conditions. I have identified the seasonal and synoptic variability of upwelling signatures on the central east coast of India, using averaged monthly and weekly sea surface temperature (SST) distributions obtained from remote sensing imagery from the Advanced Very High Resolution Radiometer in the period from 2000 to 2003. Analyse the seasonal mean variability of the upwelling-forced conditions, the average monthly PFEL coastal upwelling index (CUI) for 1990 through 2003 have been calculated for the entire central east coast with latitude resolution of 0.5°, attending to the local coastline orientation for each point. The index also shows a near-perfect confirmation of both the upwelling intensification during March, and the decrease of upwelling-favorable conditions towards the south. Spectra calculated using entire time series of from 2000 to 2003 wind data show that the frequency ranges from 0.1 to 0.2 cycles/day (corresponding to periods of 5 to 10 days) and has a number of significant energy peaks. The presence of energy frequency ranges from 0.1 to 0.2 cycles/day became evident, especially for the Visakhapatnam and Chennai stations.

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View on Bay of Bengal upwelling area on the basis of 19-years of satellite sea surface temperature

Cited by 14 publications

References 9 publications

Aerosol Induced Changes in Sea Surface Temperature Over the Bay of Bengal Due to COVID-19 Lockdown

Aerosol Induced Changes in Sea Surface Temperature Over the Bay of Bengal Due to COVID-19 Lockdown

Coastal Upwelling in the Bay of Bengal: Role of Local and Remote Windstress

Coastal upwelling activity along the central east coast of India

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