Variability of Diurnal Sea Surface Temperature during Short Term and High SST Event in the Western Equatorial Pacific as Revealed by Satellite Data

Anindya Wirasatriya,Joga Dharma Setiawan,Kohtaro Hosoda,R. Dwi Susanto

doi:10.3390/rs12193230

Abstract

Near-surface diurnal warming is an important process in the climate system, driving exchanges of water vapor and heat between the ocean and the atmosphere. The occurrence of the hot event (HE) is associated with the high diurnal sea surface temperature amplitude (δSST), which is defined as the difference between daily maximum and minimum sea surface temperature (SST). However, previous studies still show some inconsistency for the area of HE occurrence and high δSST. The present study produces global δSST data based on the SST, sea surface wind data derived from microwave radiometers, and solar radiation data obtained from visible/infrared radiometers. The value of δSSTs are estimated and validated over tropical oceans and then used for investigating HE in the western equatorial Pacific. A three-way error analysis was conducted using in situ mooring buoy arrays and geostationary SST measurements by the Himawari-8 and Geostationary Operational Environmental Satellite (GOES). The standard deviation error of daily and 10-day validation is around 0.3 °C and 0.14–0.19 °C, respectively. Our case study in the western Pacific (from 110°E to 150°W) shows that the area of HE occurrence coincided well with the area of high δSST. Climatological analysis shows that the collocated area between high occurrence rate of HE and high δSST, which coincides with the western Pacific warm pool region in all seasons. Thus, this study provides more persuasive evidence of the relation between HE occurrence and high δSST.

Highlights

Sea surface temperature (SST) has a typical daily cycle, called diurnal SST
Absolute values of biases by both δSST and SSTfnd were less than 0.05 ◦C, while their standard deviation (STDV) was 0.25 ◦C and 0.41 ◦C, respectively
This paper describes the calculation, validation, and a climate study application of the diurnal SST range estimations using satellite observation data (SST, sea surface wind (SSW), and SR)

Summary

Introduction

Sea surface temperature (SST) has a typical daily cycle, called diurnal SST. The generation of diurnal SST is mainly caused by the changes in solar heating as a result of day and night differences. The amplitude/range of the diurnal SST variation (δSST) is enhanced up to more than 3 ◦C under the calm and clear conditions [1,2,3,4]. Bernie et al [10] and Li et al [11] indicated that the diurnal SST variation influences the atmosphere over the western Pacific warm pool. Gas exchange, such as carbon dioxide flux at the sea surface [12], is affected by diurnal SST cycle, and it has been suggested that including the diurnal cycle in the calculations of climate model could improve representations of climate variability [7]. ΔSST variation determines the formation of the short period and high SST phenomena, called hot event (HE) [18,19,20]

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