EGU21-15747
https://doi.org/10.5194/egusphere-egu21-15747
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Influence of coastal upwelling on the surface current in the Bay of Bengal using HF radar and satellite observations

Shouvik Dey1, Sourav Sil2, and Samiran Mandal3
Shouvik Dey et al.
  • 1Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (sd58@iitbbs.ac.in)
  • 2Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (souravsil@iitbbs.ac.in)
  • 3Ocean Analysis and Modeling Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha-752050, India (sm18@iitbbs.ac.in)

Coastal Upwelling is a phenomenon in which cold and nutrient-enriched water from the Ekman layers reaches the surface enhancing the biological productivity of the upwelling region. In this work, an attempt is made to understand the influence of coastal upwelling on surface current variations during May 2018 to August 2018, when HF radar current observation (source: NIOT, India) is available. The wind-based Upwelling Index(UIwind) showed coastal upwelling throughout the study period. But the SST based upwelling index (UIsst) showed upwelling occurred only from May to the first week of June. Cross-shore components of HF radar-derived ocean surface current (CSSC)  showed strong similarity with UIsst. The first phase of upwelling from UIsst is observed to start on 5th May and lasts till 14th May with a maximum peak on around 10th May and having a horizontal extension of ~40 km. Then, there is a break period for about three days and after that, the second phase of upwelling starts on 17th May and lasts till 25th May with a maximum peak on around 20th May, but this time the horizontal extension is ~100 km which is much larger than during the first phase. A strong positive (from coast to offshore) CSSC is observed to start on around 5th May and lasts till 13th May with a maximum peak on around 10th May and having a horizontal extension of ~40 km, as observed from UIsst. A reversal of CSSC (towards coast) is noted on 14th May when the break of coastal upwelling is evident from UIsst. The CSSC then again started intensifying 15th May onwards and continued for ten days till 25th May, similar to UIsst.  The horizontal extension of the upwelling signature in the second phase of upwelling is ~70 km. Therefore, a 7-10 days of the coastal upwelling and its horizontal extension are identified in this study. This study suggests the use of high resolution (~6 km) HF radar current observation on the monitoring of coastal upwelling processes.

How to cite: Dey, S., Sil, S., and Mandal, S.: Influence of coastal upwelling on the surface current in the Bay of Bengal using HF radar and satellite observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15747, https://doi.org/10.5194/egusphere-egu21-15747, 2021.