ArticlePDF Available

Spatial and Temporal Analysis of Satellite derived Sea Surface Salinity in the Northern Bay of Bengal

December 2019

December 2019

Authors:

Muhammad Shahinur Rahman

Bangladesh Oceanographic Research Institute

Md. Kawser Ahmed

University of Dhaka

Bangladesh Oceanographic Research Institute

Show all 6 authorsHide

Contemporary development of satellite can enable us to analyse geophysical parameters with high spatiotemporal resolution. Variability of Soil Moisture Active Passive (SMAP) derived sea surface salinity (SSS) and Freshwater flux (E-P) during January 2016-December 2018 in the Northern Bay of Bengal (NBOB) is analysed in this paper. The highest SSS value occurred in May 2017 with the value of 32.9 psu while the lowest value 27.8 psu was observed in October 2017. Low saline water is seen all around the year in the mouth of Ganga-Brahmaputra and extended to the western part with the increase of river discharge in summer and fall intermonsoon. The Irrawaddy River influences the eastern part in the winter time. E-P value shows that northern and eastern part experienced with negative E-P and the western part is experienced with positive E-P. Partial correlation among SSS, E-P, SST and Chlrophyll-a (Chl-a) indicated there is a positive correlation between SSS and Chl-a. There is no significant correlation among other parameters, and possible reason is the high spatial variability.

Content uploaded by Muhammad Shahinur Rahman

Content may be subject to copyright.

ResearchGate has not been able to resolve any citations for this publication.

ResearchGate has not been able to resolve any references for this publication.

Article

Full-text available

Simulation of Tropical Cyclone Viyaru using Weather Research and Forecasting (WRF-ARW) mesoscale mod...

December 2019

In this present study the cyclonic storm Viyaru which formed over the Bay of Bengal during 10-17 May 2013 in pre-monsoon and stroke the Chittagong coast of Bangladesh was simulated using the Weather Research and Forecasting (WRF)-Advanced Research WRF model. This mesoscale model (WRF-ARW) has been used to evaluate their performances for the simulation of the TC events, especially cyclone tracks ... [Show full abstract] and thermo-dynamical features associated with the development of cyclones such as sea level pressure (SLP), Wind fields and vorticity freld. The horizontal resolution of 90 km for mother domain wa's used in the model. The NCEP FNL data of lx1degree resolution have been used as initial field and lateral boundary conditions. The WRF model with two domain systems have been running for 96, 72, 48, 24 hours for making several sets of numerical experiments. The simulated parameters of WRF model are compared with the data obtained from the Indian Meteorological Department (IMD). The track, minimum sea level pressure (MSLP), maximum wind speed (MWS) at 10 m level and vorticity have been analyzed to understand where the landfall of the TC Viyaru occurred. The model simulated track obtained from WRF model is parallel to observed track but it is deviated in the eastern side of the observed track. The track obtained from WRF model for 96 hours hindcast is the best among other simulations.

Article

Full-text available

Estimation of primary productivity using vertically generalized production model in the Northern par...

June 2018

The study was carried out with the estimation of primary productivity using vertically generalized production model (VGPM) in the northern part of Bay of Bengal (BoB). The model was first proposed by Behrenfeld and FaWowski in 1997 and provided good results for estimation of primary productivity in the coastal area. Productivity was estimated for four months (December, January, February and ... [Show full abstract] March) for five years from 2012 -2019 using remotely sensed satellite data. Estimated primary production was ranged from 25-3500 mgCm-2d-1 over the region. Productivity was comparatively higher at the river mouth of Ganges-Brahmaputra-Meghna river system following decreasing pattern to the open part of the southward region. Among four months, February was experienced with the highest productivity varied from 65-3500 mgCm-2d-1, BOB receives a large freshwater influx and nutrients from the riverine system which enhance primary production in some area near the river mouth but the entire BoB remains less productive due to the strong stratified layer in the upper ocean.

Article

Full-text available

The response of the upper ocean to tropical cyclone Viyaru over the Bay of Bengal

February 2019 · Acta Oceanologica Sinica -English Edition-

Better forecast of tropical cyclone (TC) can help to reduce risk and enhance management. The TC forecast depends on the scientific understanding of oceanic processes, air-sea interaction and finally, the atmospheric process. The TC Viyaru is taken as an example, which is formed at the end of 11 May 2013 and sustains up to 17 May 2013 during pre-monsoon season. Argo data are used to investigate ... [Show full abstract] ocean response processes by comparing pre-and post-conditions of the TC. Eight oceanic parameters including the sea surface temperature (SST), the sea surface salinity (SSS), and the barrier layer thickness (BLT), the 26°C isotherm depth in the ocean (D 26), the isothermal layer depth (ILD), the mixed layer depth (MLD), the tropical cyclone heat potential (TCHP) and the effective oceanic layer for cyclogenesis (EOLC) are chosen to evaluate the pre-and post-conditions of the TC along the track of Viyaru. The values of the SST, D 26 , BLT, TCHP and EOLC in the pre-cyclonic condition are higher than the post-cyclonic condition, while the SSS, ILD and MLD in the post-cyclonic condition are higher than the pre-cyclonic condition of the ocean due to strong cyclonic winds and subsurface upwelling. It is interesting that the strong intensity of the TC reduces less SST and vice versa. The satisfied real time Argo data is not available in the northern Bay of Bengal especially in the coastal region. A weather research and forecasting model is employed to hindcast the track of Viyaru, and the satellite data from the National Center Environmental Prediction are used to assess the hindcast. Key words: effective oceanic layer for cyclogenesis, sea surface temperature, tropical cyclone, tropical cyclone heat potential, tropical cyclone viyaru, weather research and forecasting model Citation: Kashem Mir, Ahmed Md Kawser, Qiao Fangli, Akhter M A E, Chowdhury K M Azam. 2019. The response of the upper ocean to tropical cyclone Viyaru over the Bay of Bengal. Acta Oceanologica Sinica, 38(1): 61-70,

Article

Assessment of seasonal and year-to-year surface salinity signals retrieved from SMOS and Aquarius mi...

March 2016

The Bay of Bengal (BoB) exhibits a wide range of sea surface salinity (SSS), with very fresh water induced by heavy monsoonal precipitation and river run-offs to the north, and saltier water to the south. This is a particularly challenging region for the application of satellite-derived SSS measurements because of the potential pollution of the SSS signal by radio frequency interference (RFI) and ... [Show full abstract] land-induced contamination in this semi-enclosed basin. The present study validates recent level-3 monthly gridded (1 degrees x 1 degrees) SSS products from Soil Moisture and Ocean Salinity (SMOS) and Aquarius missions to an exhaustive in situ SSS product for the BoB. Current SMOS SSS retrievals do not perform better than existing climatologies. This is in stark contrast to Aquarius, which outperforms SMOS and available SSS climatologies everywhere in the BoB. While SMOS only captures the SSS seasonal evolution in the northern part of the Bay, Aquarius accurately captures the seasonal signal in the entire basin. The Aquarius product is also able to capture SSS non-seasonal anomalies, with an approximate correlation (r) of 0.75 with box-averaged in situ data in the northern, central, and western parts of the Bay. Aquarius can, thus, be confidently used to monitor large-scale year-to-year SSS variations in the BoB.