Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip...Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip of Sri Lanka or Palk Strait. Local circulation patterns impact the pathways followed by the East Indian Coastal Currents(EICC) that drive exchange, thereby modulating mixing and water mass transformation in the Bay of Bengal around Sri Lanka. In this study, observations from surface drifters were incorporated with the satellite derived data to understand the monsoonal impact on circulation patterns in the Indian Ocean. This was the first multi-national scientific effort which was conducted in the Bo B and AS during 2013 to 2015 to understand the monsoonal impact on circulation patterns in the complex region. The results indicated that seasonally reversing monsoonal currents of southern Sri Lanka, traced by the wintertime freshwater export pathways of the EICC. The deflection of monsoon currents running along the east coast of Sri Lanka by forming cyclonic and anti-cyclonic eddies, which influence the mixing and stirring associated with these flows. Results further indicate the low salinity cold water flows from the Bo B to AS along the western boundary of the Bo B during northeast monsoon. In the same way, reverses the phenomena during southwest monsoon, transporting high salinity warm water from AS to the Bo B. This maintain the bay status which occurred due to freshwater influx from large rivers and high saline water from AS. However, no evidences were observed for the exchange through Palk Strait during the study.Also, there are some mis-matches in in-situ and remotely sensed measurements which imply the necessity of systematic observation system for the complex region as an alternative approach.展开更多
Time series measurements (2010–2017) from the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA) moorings at 15°N,90°E and 12°N,90°E are used to investigat...Time series measurements (2010–2017) from the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA) moorings at 15°N,90°E and 12°N,90°E are used to investigate the effect of the seasonal barrier layer (BL) on the mixed-layer heat budget in the Bay of Bengal (BoB).The mixed-layer temperature tendency (?T/?t) is primarily controlled by the net surface heat flux that remains in the mixed layer(Q’) from March to October,while both Q’and the vertical heat flux at the base of the mixed layer (Q_(h)),estimated as the residual of the mixed-layer heat budget,dominate during winter (November–February).An inverse relation is observed between the BL thickness and the mixed-layer temperature (MLT).Based on the estimations at the moorings,it is suggested that when the BL thickness is≥25 m,it exerts a considerable influence on ?T/?t through the modulation of Q_(h) (warming) in the BoB.The cooling associated with Q_(h) is strongest when the BL thickness is≤10 m with the MLT exceeding 29°C,while the contribution from Q_(h) remains nearly zero when the BL thickness varies between 10 m and 25 m.Temperature inversion is evident in the BoB during winter when the BL thickness remains≥25 m with an average MLT<28.5°C.Furthermore,Q_(h) follows the seasonal cycle of the BL at these RAMA mooring locations,with r>0.72 at the 95%significance level.展开更多
文摘Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip of Sri Lanka or Palk Strait. Local circulation patterns impact the pathways followed by the East Indian Coastal Currents(EICC) that drive exchange, thereby modulating mixing and water mass transformation in the Bay of Bengal around Sri Lanka. In this study, observations from surface drifters were incorporated with the satellite derived data to understand the monsoonal impact on circulation patterns in the Indian Ocean. This was the first multi-national scientific effort which was conducted in the Bo B and AS during 2013 to 2015 to understand the monsoonal impact on circulation patterns in the complex region. The results indicated that seasonally reversing monsoonal currents of southern Sri Lanka, traced by the wintertime freshwater export pathways of the EICC. The deflection of monsoon currents running along the east coast of Sri Lanka by forming cyclonic and anti-cyclonic eddies, which influence the mixing and stirring associated with these flows. Results further indicate the low salinity cold water flows from the Bo B to AS along the western boundary of the Bo B during northeast monsoon. In the same way, reverses the phenomena during southwest monsoon, transporting high salinity warm water from AS to the Bo B. This maintain the bay status which occurred due to freshwater influx from large rivers and high saline water from AS. However, no evidences were observed for the exchange through Palk Strait during the study.Also, there are some mis-matches in in-situ and remotely sensed measurements which imply the necessity of systematic observation system for the complex region as an alternative approach.
基金The Strategic Priority Research Program of Chinese Academy of Sciences under contract No.XDA 20060502the National Natural Science Foundation of China under contract Nos 41976016, 42076021 and 41521005+4 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory under contract No.GML2019ZD0306the Guangdong Basic and Applied Basic Research Foundation under contract No.2021A1515011534the Grant for Innovation Academy of South China Sea Ecology and Environmental Engineering,Chinese Academy of Sciences under contract No.ISEE2021ZD01the Grant for State Key Laboratory of Tropical OceanographySouth China Sea Institute of Oceanology under contract No.LTOZZ2002。
文摘Time series measurements (2010–2017) from the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA) moorings at 15°N,90°E and 12°N,90°E are used to investigate the effect of the seasonal barrier layer (BL) on the mixed-layer heat budget in the Bay of Bengal (BoB).The mixed-layer temperature tendency (?T/?t) is primarily controlled by the net surface heat flux that remains in the mixed layer(Q’) from March to October,while both Q’and the vertical heat flux at the base of the mixed layer (Q_(h)),estimated as the residual of the mixed-layer heat budget,dominate during winter (November–February).An inverse relation is observed between the BL thickness and the mixed-layer temperature (MLT).Based on the estimations at the moorings,it is suggested that when the BL thickness is≥25 m,it exerts a considerable influence on ?T/?t through the modulation of Q_(h) (warming) in the BoB.The cooling associated with Q_(h) is strongest when the BL thickness is≤10 m with the MLT exceeding 29°C,while the contribution from Q_(h) remains nearly zero when the BL thickness varies between 10 m and 25 m.Temperature inversion is evident in the BoB during winter when the BL thickness remains≥25 m with an average MLT<28.5°C.Furthermore,Q_(h) follows the seasonal cycle of the BL at these RAMA mooring locations,with r>0.72 at the 95%significance level.
