Application of Nonstationary Extreme Value Analysis to Satellite-Observed Sea Surface Temperature Data for Past Decades

Presented at the GHRSST XXIII international science team meeting, 27 June-1 July 2022, online and in-person (Barcelona). #GHRSST23

Short abstract

This study provides the recent ISAR observations in the seas surrounding the Korean Peninsula, the Indian Ocean, and the Northwest Pacific Ocean. To understand the characteristics of the sea surface temperature (SST) and its overall vertical structure, we collocated the ISAR temperatures and those from satellite SST, surface drifter, ARGO float, and shipborne thermosalinograph of R/V ISABU. The skin temperature was mostly lower than that of the satellite, and the difference between the two temperatures indicated a diurnal variation. Similar to the results of previous studies, the skin-bulk temperature differences tended to be amplified in the low wind speed. The amplitude of the diurnal fluctuation was inversely proportional to the wind speed, so it was more positively amplified during the day and a relatively small negative bias at night. The differences between surface drifter temperatures and ARGO temperatures also exhibited a diurnal variation with a bias of –0.05K before 9 AM, reaching its highest peak of about 0.2K around 3 PM, and gradually decreased at night. The amplitudes of these temperature differences showed a seasonality with bimodality of the first maximum value in March-April and the secondary peak in September-October. Under low wind condition, the drifter-ARGO temperature differences also showed dominant skin-bulk temperatures differences. The analyses of the temperature differences enabled to understand the comprehensive characteristics of vertical temperature structure and roles of wind speed and stability on diurnal/seasonal variations. More ISAR observations are needed for a substantial understanding of ocean warming in response to climate change.