Modeled surface salinity and satellite data as proxy for Secchi depth and watercolor of the Gulf of Riga

Institute of Numerical Modelling, Faculty of Physics Mathematics and Optometry University of Latvia, Jelgavas str. 3, Riga, Latvia

^* Corresponding author: daiga.cepite-frisfelde@lu.lv

Abstract

The present study pays attention to the sea surface salinity field and satellite derived watercolor and Secchi depth datasets in the Gulf of Riga in 1998-2018. The study increases understanding of the river plume’s impact on the open part of the Gulf of Riga. Mean watercolor and salinity versus depth had been compared in April and August month. The region with the high mean watercolor and salinity homogeneity consistency had been seen in the deepest part (depth >40m) of the Gulf of Riga in April. The correlation between mean salinity field and watercolor and Secchi depth data sets had been shown. It marks the coastal and transitional region where the current of riverine water on the sea surface dominate the upwelling from the more saline deeper layers. The study distinguishes mean watercolor (in situ observations and derived from satellite) in years with and without seasonal hypoxia in the Gulf of Riga in 2005-2018. Convincing difference between both sets have not been found.