Relationship of mixed layer depth and sea surface temperature onlongwave radiation flux up in the west of Sumatra waters

Abstract

Thermal energywhich stored in upper ocean mixed layer will be released in the form oflongwave radiation flux up (LWUp). LW Up is a longwavethat emitted from sea surface to atmosphere. Variability of upper ocean mixed layerhas influence on ocean thermal capacity and then affected LW Up variation. The areaof interest of this research was west of Sumatra waters. Vertical temperature profiles, sea surface temperature (SST) and LW Updata from 2000 to 2015 were used. Mixed layer depth (MLD) was computedbyThreshold Method based on temperature profiles with 0.31°Ctemperature criterion (ΔT). The results show high LW Up flux occur during shallow MLD and low LW Up occur when MLD become deeper. Correlation between SST and LW Up give a fine value about 0.9 in all station. Good correlation coefficient between MLD and LW Up found in station 1 (-0.81) and 9 (-0.77) with 1 month lag. This results suggest that shallow (deep) MLD followed by high (low) SST so that the result is increase (decrease) LW Up by 1 month lag. Small correlation between MLD and LW Up found in area near equator region. Indian Ocean circulation, westerly wind, and Wyrtki jet are possibly causing the small correlation in equator region.