Hydrological fronts seen in visible and infrared MODIS imagery of the Black Sea

Abstract

This article presents an examination of hydrological fronts in the Black Sea based on visible and infrared Aqua Moderate Resolution Imaging Spectrometer (MODIS) imagery obtained during 2008–2013. First the images were preliminarily treated (e.g. via applying a median filter) and then the fronts were detected using the Sobel operator. Further processing of the fields of the gradient norm thus obtained helped determine the generalized results of the front density for different years and seasons. On analysis of such results it was shown that the strongest thermal and optical fronts in the Black Sea are located in the near-coastal area. Nevertheless, analysis of the front density contrasts in the open sea was discovered to be very helpful as well, because it provided important information on the trajectories of the main macro- and mesoscale circulation patterns in the basin such as the Rim Current, Batumi eddy, and eddies of the Anatolian coast.