Variability of Decadal Horizontal Thermohaline Gradients on the Surface of the Barents Sea during Summer Season in 1993-2022

Purpose. The paper is aimed at comparative analysis of the decadal horizontal gradients of thermohaline fields in the Barents Sea during the summer periods in 1993-2022 derived from the reanalysis and satellite measurements with the aim to select the most suitable data array for studying the surface manifestations of frontal zones. Methods and Results. The fields of decadal and background thermohaline gradients on the Barents Sea surface were calculated for the summer periods in 1993-2022 based on the monthly mean temperature data from GHRSST OSTIA, MODIS/Aqua, and VIIRS/Suomi NPP, as well as on the monthly mean temperature and salinity data from CMEMS GLORYS12V1 and MERCATOR PSY4QV3R1. The quantitative estimates of temperature and salinity gradients were obtained for certain decades using different data arrays, and a comparative analysis of these estimates was performed along with a description of the physical and geographical characteristics of frontal zones. Maximum thermohaline gradients on the surface were observed in July. Based on the data from all the sources, the background horizontal thermal gradient has been increasing over three decades. During a summer period, the Polar Frontal Zone was identified on the surface of the Barents Sea in all the data arrays, whereas the Coastal and Arctic Frontal Zones were observed in the salinity field based on the CMEMS GLORYS12V1 and MERCATOR PSY4QV3R1 data. Conclusions. The difference between the calculated estimates of horizontal temperature gradient can exceed 0.01 degrees C/km that is comparable to the magnitude of the average climate gradient in the Barents Sea. The thermal gradient values obtained from the CMEMS GLORYS12V1 and MERCATOR PSY4QV3R1 reanalysis data are the closest to this estimate. This fact makes it possible to classify these data arrays as the most preferable ones for the analysis of the surface manifestations of frontal zones in the Barents Sea.