Analysis of the variability of temperature gradient in the ocean frontal zones based on satellite data

AVHRR MCSST data for the periods 1982-2000 (mean weekly data) were used to calculate mean gradient fields in the ocean for different periods of time. Three-month averaged sea surface temperature gradients (SSTG) and their mean seasonal variations have been studied for 25 points in the large-scale oceanic fronts zones. Major oceanic fronts in the Atlantic and Pacific have been identified and compared in literature. In the North Atlantic and Pacific, the areas under study were the North Polar Front and Subpolar Fronts. In the South Atlantic and Pacific we studied the region of the Antarctic Circumpolar Current (ACC) and the fronts formed by this current, known as the South Polar Front, and the Subantarctic Front. SSTG were also calculated for El Nino (Southeast Pacific) and Benguela Current (Southeast Atlantic). In warm periods seasonal SSTG in the North Atlantic markedly increased and exhibit some interannual cycles. The correlation between the North Atlantic Oscillation index and seasonal SSTG for a single point in the Gulf Stream zone can be the key point for evaluation of heat transfer by the currents to the coast of East Europe. In the Southern Atlantic, the SSTG values are low during the cold period (summer in the southern hemisphere) in the ACC zone and increase in the warm season (winter in the southern hemisphere). It also exhibits interannual cycles. In the Northwest Pacific for some points in the Subpolar Front the SSTG values are high in the cold period (winter). Here at seven points in the spring of 1993 and 2000 the calculations disclosed significant increase of the gradient. In these years, the anomalous SSTG in Subpolar Front and South Polar Front were found to vary synchronously in both hemispheres, with maximum intensity in spring (North Pacific) and in summer (South Pacific). Mean annual SSTG in the El Nino zone and south oscillation index have been found to exhibit some correlation. Major jet currents periodically form high-gradient temperature fields and from the temperature satellite data we can derive information about variation in the large-scale fronts in the Global Ocean. (C) 2013 COSPAR. Published by Elsevier Ltd. All rights reserved.