All Time Past Year Past 30 Days
Abstract Views 118 118 31
Full Text Views 41 41 8
PDF Downloads 61 61 9

Seasonal and year-to-year variability of boundary currents and eddy salt flux along the eastern and southern coasts of Sri Lanka observed by PIES and satellite measurements

View More View Less
  • 1 aScripps Institution of Oceanography, La Jolla, California, USA.
  • | 2 bThe Institute of Marine Science, Burapha University, Chonburi, Thailand.
  • | 3 cApplied Physics Laboratory, University of Washington, Seattle, Washington, USA.
  • | 4 dNational Aquatic Resources Research & Development Agency, Colombo, Sri Lanka.
  • | 5 eThe Ocean University of Sri Lanka, Colombo, Sri Lanka
Restricted access

Abstract

Boundary currents along the Sri Lankan eastern and southern coasts serve as a pathway for salt exchange between the Bay of Bengal and the Arabian Sea basins in the northern Indian Ocean that are characterized by their contrasting salinities. Measurements from two pairs of Pressure-sensing Inverted Echo Sounders (PIES) deployed along the Sri Lankan eastern and southern coasts as well as satellite measurements are used to understand the variability of these boundary currents and the associated salt transport. The volume transport in the surface (0-200 m depth) layer exhibits a seasonal cycle associated with the monsoonal wind reversal and interannual variability associated with the Indian Ocean Dipole (IOD). In this layer, the boundary currents transport low-salinity water out of the Bay of Bengal during the northeast monsoon, and transport high-salinity water into the Bay of Bengal during the fall monsoon transition of some years (e.g., 2015 and 2018). The Bay of Bengal salt input increases during the 2016 negative IOD as the eastward flow of highsalinity water during the fall monsoon transition intensifies, while the effect of the 2015/2016 El Niño on the Bay of Bengal salt input is still unclear. The time-mean eddy salt flux over the upper 200 m estimated for the April 2015 - March 2019 (December 2015 - November 2019) period along the eastern (southern) coast accounts for 9% (27%) of the salt budget required to balance an estimated 0.13 Sv of annual freshwater input into the Bay of Bengal.

Corresponding author: Arachaporn Anutaliya, arachaporn.an@go.buu.ac.th

Abstract

Boundary currents along the Sri Lankan eastern and southern coasts serve as a pathway for salt exchange between the Bay of Bengal and the Arabian Sea basins in the northern Indian Ocean that are characterized by their contrasting salinities. Measurements from two pairs of Pressure-sensing Inverted Echo Sounders (PIES) deployed along the Sri Lankan eastern and southern coasts as well as satellite measurements are used to understand the variability of these boundary currents and the associated salt transport. The volume transport in the surface (0-200 m depth) layer exhibits a seasonal cycle associated with the monsoonal wind reversal and interannual variability associated with the Indian Ocean Dipole (IOD). In this layer, the boundary currents transport low-salinity water out of the Bay of Bengal during the northeast monsoon, and transport high-salinity water into the Bay of Bengal during the fall monsoon transition of some years (e.g., 2015 and 2018). The Bay of Bengal salt input increases during the 2016 negative IOD as the eastward flow of highsalinity water during the fall monsoon transition intensifies, while the effect of the 2015/2016 El Niño on the Bay of Bengal salt input is still unclear. The time-mean eddy salt flux over the upper 200 m estimated for the April 2015 - March 2019 (December 2015 - November 2019) period along the eastern (southern) coast accounts for 9% (27%) of the salt budget required to balance an estimated 0.13 Sv of annual freshwater input into the Bay of Bengal.

Corresponding author: Arachaporn Anutaliya, arachaporn.an@go.buu.ac.th
Save