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Delineation of marine ecosystem zones in the northern Arabian Sea during winter

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dc.contributor.author Shalin, S
dc.contributor.author Samuelsen, A
dc.contributor.author Korosov, A
dc.contributor.author Menon, N
dc.contributor.author Backeberg, Bjorn-Christoph
dc.contributor.author Pettersson, LH
dc.date.accessioned 2018-06-15T06:24:30Z
dc.date.available 2018-06-15T06:24:30Z
dc.date.issued 2018-03
dc.identifier.citation Shalin, S. et al. 2018. Delineation of marine ecosystem zones in the northern Arabian Sea during winter. Biogeosciences, vol. 15(5): 1395-1414 en_US
dc.identifier.issn 1726-4170
dc.identifier.issn 1726-4189
dc.identifier.uri https://doi.org/10.5194/bg-15-1395-2018
dc.identifier.uri https://www.biogeosciences.net/15/1395/2018/
dc.identifier.uri http://hdl.handle.net/10204/10258
dc.description © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. en_US
dc.description.abstract The spatial and temporal variability of marine autotrophic abundance, expressed as chlorophyll concentration, is monitored from space and used to delineate the surface signature of marine ecosystem zones with distinct optical characteristics. An objective zoning method is presented and applied to satellite-derived Chlorophyll a (Chl a) data from the northern Arabian Sea (50–75 degrees E and 15–30 degrees N) during the winter months (November–March). Principal component analysis (PCA) and cluster analysis (CA) were used to statistically delineate the Chl a into zones with similar surface distribution patterns and temporal variability. The PCA identifies principal components of variability and the CA splits these into zones based on similar characteristics. Based on the temporal variability of the Chl a pattern within the study area, the statistical clustering revealed six distinct ecological zones. The obtained zones are related to the Longhurst provinces to evaluate how these compared to established ecological provinces. The Chl a variability within each zone was then compared with the variability of oceanic and atmospheric properties viz. mixed-layer depth (MLD), wind speed, sea-surface temperature (SST), photosynthetically active radiation (PAR), nitrate and dust optical thickness (DOT) as an indication of atmospheric input of iron to the ocean. The analysis showed that in all zones, peak values of Chl a coincided with low SST and deep MLD. The rate of decrease in SST and the deepening of MLD are observed to trigger the algae bloom events in the first four zones. Lagged cross-correlation analysis shows that peak Chl a follows peak MLD and SST minima. The MLD time lag is shorter than the SST lag by 8 days, indicating that the cool surface conditions might have enhanced mixing, leading to increased primary production in the study area. An analysis of monthly climatological nitrate values showed increased concentrations associated with the deepening of the mixed layer. The input of iron seems to be important in both the open-ocean and coastal areas of the northern and north-western parts of the northern Arabian Sea, where the seasonal variability of the Chl a pattern closely follows the variability of iron deposition. en_US
dc.language.iso en en_US
dc.publisher Copernicus Publications en_US
dc.relation.ispartofseries Worklist;20871
dc.subject Arabian sea en_US
dc.subject surface Chl a en_US
dc.subject phytoplankton en_US
dc.title Delineation of marine ecosystem zones in the northern Arabian Sea during winter en_US
dc.type Article en_US
dc.identifier.apacitation Shalin, S., Samuelsen, A., Korosov, A., Menon, N., Backeberg, B., & Pettersson, L. (2018). Delineation of marine ecosystem zones in the northern Arabian Sea during winter. http://hdl.handle.net/10204/10258 en_ZA
dc.identifier.chicagocitation Shalin, S, A Samuelsen, A Korosov, N Menon, Bjorn-Christoph Backeberg, and LH Pettersson "Delineation of marine ecosystem zones in the northern Arabian Sea during winter." (2018) http://hdl.handle.net/10204/10258 en_ZA
dc.identifier.vancouvercitation Shalin S, Samuelsen A, Korosov A, Menon N, Backeberg B, Pettersson L. Delineation of marine ecosystem zones in the northern Arabian Sea during winter. 2018; http://hdl.handle.net/10204/10258. en_ZA
dc.identifier.ris TY - Article AU - Shalin, S AU - Samuelsen, A AU - Korosov, A AU - Menon, N AU - Backeberg, Bjorn-Christoph AU - Pettersson, LH AB - The spatial and temporal variability of marine autotrophic abundance, expressed as chlorophyll concentration, is monitored from space and used to delineate the surface signature of marine ecosystem zones with distinct optical characteristics. An objective zoning method is presented and applied to satellite-derived Chlorophyll a (Chl a) data from the northern Arabian Sea (50–75 degrees E and 15–30 degrees N) during the winter months (November–March). Principal component analysis (PCA) and cluster analysis (CA) were used to statistically delineate the Chl a into zones with similar surface distribution patterns and temporal variability. The PCA identifies principal components of variability and the CA splits these into zones based on similar characteristics. Based on the temporal variability of the Chl a pattern within the study area, the statistical clustering revealed six distinct ecological zones. The obtained zones are related to the Longhurst provinces to evaluate how these compared to established ecological provinces. The Chl a variability within each zone was then compared with the variability of oceanic and atmospheric properties viz. mixed-layer depth (MLD), wind speed, sea-surface temperature (SST), photosynthetically active radiation (PAR), nitrate and dust optical thickness (DOT) as an indication of atmospheric input of iron to the ocean. The analysis showed that in all zones, peak values of Chl a coincided with low SST and deep MLD. The rate of decrease in SST and the deepening of MLD are observed to trigger the algae bloom events in the first four zones. Lagged cross-correlation analysis shows that peak Chl a follows peak MLD and SST minima. The MLD time lag is shorter than the SST lag by 8 days, indicating that the cool surface conditions might have enhanced mixing, leading to increased primary production in the study area. An analysis of monthly climatological nitrate values showed increased concentrations associated with the deepening of the mixed layer. The input of iron seems to be important in both the open-ocean and coastal areas of the northern and north-western parts of the northern Arabian Sea, where the seasonal variability of the Chl a pattern closely follows the variability of iron deposition. DA - 2018-03 DB - ResearchSpace DP - CSIR KW - Arabian sea KW - surface Chl a KW - phytoplankton LK - https://researchspace.csir.co.za PY - 2018 SM - 1726-4170 SM - 1726-4189 T1 - Delineation of marine ecosystem zones in the northern Arabian Sea during winter TI - Delineation of marine ecosystem zones in the northern Arabian Sea during winter UR - http://hdl.handle.net/10204/10258 ER - en_ZA


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