Temporal and Spatial Variations of Monsoonal Upwelling along the South West and East Coasts of India

Patel, Shailee; Vithalpura, Manisha; Mallick, Subrat Kumar; Ratheesh, Smitha

doi:10.1080/01490419.2019.1703061

Cited by 8 publications

(19 citation statements)

References 47 publications

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“…It is obvious as the summer monsoon winds in the AS are characterized by very strong and persistent southwesterlies (Fig. 1b) favouring coastal upwelling along the Somali coast, Oman coast and west coast of India (McCreary & Kundu, 1989;Patel et al, 2019;Resplandy et al, 2011;Schott & McCreary, 2001). Associated variability in SST is evident in those regions.…”

Section: Resultsmentioning

confidence: 96%

“…The western coast of India shows zones of strong coupling during the summer monsoon, which are associated with wind-driven coastal upwelling (Patel et al, 2019). These zones display a strong SST gradient (Fig.…”

Section: Role Of Background Wind Fieldsmentioning

confidence: 99%

“…However, this analysis is quite complicated, as it involves several spatial and temporal scales. At large spatial scale, or the so-called basin scale, stronger winds cause more mixing, giving rise to surface waters of relatively low temperature (Kampf & Chapman, 2016;Patel et al, 2019;Sharma, 1978). This observed negative correlation between wind and sea surface temperature (SST) characterizes the basin-scale impact of the atmosphere on the ocean circulation (Okumoro et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Monsoonal Variability in the Mesoscale Coupling of Wind and SST in the Arabian Sea

Ratheesh

Chaudhary

Bhowmick

et al. 2021

Pure Appl. Geophys.

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Satellite observations over the Arabian Sea (AS) have revealed a strong signature of air-sea interaction during the Indian Ocean monsoon. In this study, satellite observations of ocean surface winds from the SCATSAT scatterometer are used to study the monsoonal variability in wind and SST (WS) coupling over the AS at the oceanic mesoscale for the period 2017 to 2019. The study investigates the role of critical parameters including SST gradient, wind speed steadiness and wind directional steadiness with respect to coupling during the winter and summer monsoons. Mesoscale WS coupling is stronger in the summer monsoon. A seasonally varying threshold of SST gradient required for the generation of WS coupling is clearly visible. This threshold is higher during the summer monsoon (0.8 °C/100 km) than during the winter monsoon (0.4 °C/100 km). Results reveal the need for a strong background wind field along with SST gradient for the generation of strong WS coupling. While a strong SST gradient ([ 0.8 °C/100 km) is sufficient to overcome the adverse influence of background wind conditions, strong support from the stable background wind fields is necessary in the regions with a relatively weak SST gradient ([ 0.4 °C/100 km) for the generation of coupling. The observed coupling between the SST and wind is quantified using a coupling coefficient. The coupling between wind stress divergence and downwind SST gradient is more prominent. It is observed that large warming of seawater (SST anomaly [ 1 °C) suppressed the positive linear coupling between anomalies of wind speed and SST in the western AS during the summer monsoon.

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Section: Resultsmentioning

confidence: 96%

Section: Role Of Background Wind Fieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Monsoonal Variability in the Mesoscale Coupling of Wind and SST in the Arabian Sea

Ratheesh

Chaudhary

Bhowmick

et al. 2021

Pure Appl. Geophys.

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“…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: 99%

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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“…Such variations cause cool and dry winters, rainy summers, variations in sea surface temperature, and ocean salinity patterns. In addition, seasonal changes in the monsoon wind regime could lead to variation in the upwelling process in oceans (Morrison et al, 1998;Jayaram and Kumar, 2018;Patel et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

An overview of Holocene monsoon variability of Sri Lanka and its association with Indian subcontinent climate records

2021

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Temporal and Spatial Variations of Monsoonal Upwelling along the South West and East Coasts of India

Cited by 8 publications

References 47 publications

Monsoonal Variability in the Mesoscale Coupling of Wind and SST in the Arabian Sea

Monsoonal Variability in the Mesoscale Coupling of Wind and SST in the Arabian Sea

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

An overview of Holocene monsoon variability of Sri Lanka and its association with Indian subcontinent climate records

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