Spatiotemporal monitoring of upwelled water motions using optical flow method in the Eastern Coasts of Caspian Sea
Autori: Ghalenoei E., Hasanlou M., Sharifi M. A., Vignudelli S., Ismael Foroughi I.
Rivista: Journal of Applied Remote Sensing
DOI: 10.1117/1.JRS.11.036016
Abstract:
Upwelling is an oceanographic process that transfers cool and nutrient-rich waters toward the sea surface. Due to the relation between low sea surface temperature (SST) and high nutrient-rich water, the upwelling regions can be easily recognized in satellite imagery. An optical flow (OF) method, Horn–Schunck, is used to discover the upwelled water motion (UWM) and its pattern using sequential (pair) SST imageries. The SST imageries of Aqua and Terra satellites between 2004 and 2012 are processed to extract the properties of upwelling in the Shevchenko area (Caspian Sea). Results show that the upwelling is periodic (with an ∼24 h period) and it matches with a Fourier model. In addition, the UWM has a specific direction from morning to night. It is also shown that the OF cannot extract correct UWM if the SST imageries are selected on different cycles. Level of chlorophyll_a in the same area is used to independently validate the existence of the upwelling.
