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Quantifying tropical cyclone's effect on the biogeochemical processes using profiling float observations in the Bay of Bengal

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Relation http://eprints.cmfri.org.in/13378/
https://agupubs.onlinelibrary.wiley.com/journal/21699291
 
Title Quantifying tropical cyclone's effect on the biogeochemical processes using profiling float observations in the Bay of Bengal
 
Creator Girish Kumar, M S
Thangaprakash, V P
Udaya Bhaskar, T V S
Suprit, K
Sureshkumar, N
Baliar Singh, S K
Jofia, J
Pant, V
Vishnu, S
George, Grinson
Abhilash, K R
Shivaprasad, S
 
Subject Oceanography
Cyclones
Remote sensing
 
Description Physical and biogeochemical observations from an autonomous profiling Argo float in the Bay of Bengal show significant changes in upper ocean structure during the passage of Tropical Cyclone (TC) Hudhud (7–14 October 2014). TC Hudhud mixed water from a depth of about 50 m into the surface layers through a combination of upwelling and turbulent mixing. Mixing was extended into the depth of nutricline, the oxycline and the subsurface‐chlorophyll‐maximum; thus had a strong impact on the biogeochemistry of the upper ocean. Before the storm, the near‐surface layer was nutrient depleted and was thus oligotrophic with the chlorophyll‐a concentration of less than 0.15 mg m‐3. Storm mixing initially increased the chlorophyll by 1.4 mg m‐3, increased the surface nitrate concentration to about 6.6 μM kg‐1, and decreased the sub‐surface dissolved oxygen (30–35 m) to 31 % of saturation (140 μM). These conditions were favorable for phytoplankton growth resulting in an estimated increase in primary productivity averaging 1.5 g C m‐2 day‐1 over 15 days. During this bloom, chlorophyll‐a increased by 3.6 mg m‐3, and dissolved oxygen increased from 111 % to 123 % of saturation. Similar observations during TC Vardah (6–12 December 2016) showed much less mixing. Our analysis suggests that relatively small (high) translation speed and presence of cold (warm) core eddy leads to strong (weak) oceanic response during TC Hudhud (TC Vardah). Thus, although cyclones can cause strong biogeochemical responses in the Bay of Bengal, the strength of response depends on the properties of the storm and the prevailing upper ocean structure such as presence of mesoscale eddies.
 
Date 2019
 
Type Article
PeerReviewed
 
Format text
 
Language en
 
Identifier http://eprints.cmfri.org.in/13378/1/Grinson%20George_2019_JGR%20Oceans_Quantifying%20tropical%20cyclone%27s%20effect%20on%20the%20biogeochemical%20processes.pdf
Girish Kumar, M S and Thangaprakash, V P and Udaya Bhaskar, T V S and Suprit, K and Sureshkumar, N and Baliar Singh, S K and Jofia, J and Pant, V and Vishnu, S and George, Grinson and Abhilash, K R and Shivaprasad, S (2019) Quantifying tropical cyclone's effect on the biogeochemical processes using profiling float observations in the Bay of Bengal. JGR Oceans. pp. 1-52.