Spatiotemporal Characteristics of Thermal Fronts in Relation to Potential Fishing Zones in the Continental Shelf Sea Around India.

Autor: Swapna, M., Raju, Reba, Nayak, Rabindra K., Mohanty, Prakash C., SeshaSai, M. V. R., Kumar, Raj
Zdroj: Journal of the Indian Society of Remote Sensing; Feb2023, Vol. 51 Issue 2, p335-348, 14p
Abstrakt: Mapping the thermal fronts is one of the important near-real-time applications of high-resolution sea surface temperature (SST) retrieved from the infrared satellite sensors such as MODIS and AVHRR to help in demarcating the areas of the potential fishing zone (PFZ). The thermal fronts are considered a proxy for the identification of PFZ from numerous studies. However, the complexity of the region and persistent cloud cover generate huge data gaps in SST images, making it challenging to provide thermal front information on a daily and synoptic scale. To overcome such difficulties, we use gap-free and blended Global 1 km SST (G1SST) products with MODIS SST to understand the inherent relationship between the datasets and their coherency to resolve spatiotemporal characteristics at a daily scale. In this regard, an edge detection algorithm developed by Cayula and Cornillon (1992) has been implemented to extract the thermal fronts from the SST datasets during 2014–2020. The algorithm is modified to suit Indian coastal oceans corresponding to MODIS SST and G1SST to resolve thermal gradients based on sensitivity experiments related to satellite-measured Chlorophyll-a and primary productivity datasets. We found that the gradient value of 0.075 °C/km is suitable for MODIS, while a relatively weaker value of 0.07°C/km for the G1SST. The weekly composite datasets of thermal front density (TFD) generated from the daily time series during the study period have been used in the least square-based harmonic analysis to investigate their observed seasonality in the continental shelf region of India. Simulation and analysis from a high-resolution ocean general circulation model have been used to investigate circulation features and associated topographic modulation for elucidating causes of the high-persistent thermal front regimes and their intra-seasonal dynamics. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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