Detection of the Kuroshio frontal instable processes (KFIP) in the East China Sea using the MODIS images

The Kuroshio frontal instable processes (KFIP) in the East China Sea (ECS) not only have a great impact on the hydrologic characteristics, the pollutants drift, the distribution of seafloor sediment and the ships navigation of the ECS, but also are closely related to the climate changes of the coastal areas of the ECS. However the frequency and area of occurrence of the KFIP have not been studied fully and detailedly. Because of its high spatial and temporal resolution, MODIS data is a kind of very good data source for surveying and researching the KFIP in the ECS. The aim of this study is to detect the KFIP in the ECS by using MODIS data, and to study the frequency and region of occurrence of the KFIP in the ECS.
The selection has coverage of level 2 data of MODIS SST and Kd490 ranging from July 1, 2002 to June 30, 2009 of the ECS when there was no cloud impact or little. By using of the data, the minimum standard of the Kuroshio temperature fronts and the diffuse attenuation coefficient (Kd490) fronts of the ECS are given. Based on these standards and the curvature distinguish methods, the standard of curvature distinguish for the KFIP in the ECS are put forward. By making use of this standard, we study a total of 2073 satellite-derived images, and discover that as long as there is no cloud impact from January to May and October to December, the KFIP in the ECS are surely found in MODIS satellite images. From June to September, the frequency of occurrence can also reach to 82.9% at least. Moreover, it is obtained that there are three source regions of these instability processes, namely, (26°N, 121.5°E) nearby, (27°N, 125°E) nearby and (30°N, 128°E) nearby. The differences of the characteristics of these instability processes which are generated in different regions are analyzed in the present study.