Inter-Comparisons of Daily Sea Surface Temperatures and In-Situ Temperatures in the Coastal Regions

Hye-Jin Woo,Kyung-Ae Park

doi:10.3390/rs12101592

Abstract

In this study, seven, global, blended, sea surface temperature (SST) analyses, including Operational SST and Sea Ice Analysis (OSTIA), Canadian Meteorological Centre (CMC) analysis, Optimum Interpolation SST (OISST), Remote Sensing System (REMSS) analysis, Multi-scale Ultra-high Resolution SST (MURSST), Merged Satellite and In situ Data Global Daily SST (MGDSST), and Geo-Polar Blended SST (Blended SST) were conducted. In-situ temperature measurements were used for the years 2014–2018, from 35 narrowly-spaced buoys distributed along the Korean Peninsula coast, to investigate how well the SST analyses represent the temperatures at the coastal regions. Contrary to the overall accuracy of the SSTs in the global ocean and offshore regions, the root-mean-square errors for the analyses were relatively large over 1.27 K. Specifically, all SST analyses resulted in warm biases over 0.31 K, which became quite distinctive in the western and the southwestern coastal regions. Investigation of the errors identified relationships with the coastal zones of vigorous tidal mixing, shallow bathymetry, and absence of microwave measurements. Overall, temporal wavelet coherency between in-situ measurements and SST products revealed high coherency of greater than 0.8 in periods longer than 180 days, however, low coherency (<0.5) in the period shorter than 10 days was observed. Inter-comparisons between the SST analyses illustrated clear spatial differences in the correlations at both the coastal regions, along the southwestern coast of the Korean Peninsula and in the frontal regions, and in the marginal seas of the Northwest Pacific. Overall, the results emphasized on the importance of using real-time in-situ measurements as much as possible, to overcome the increasing SST errors in coastal regions.

Highlights

Sea surface temperature (SST) is a major oceanic variable that plays an important role as an indicator of climate change and as input data for the numerical models used for weather forecasting and oceanic circulation prediction [1,2,3,4]
It is essential to identify the advantages and disadvantages of each sea surface temperature (SST) analysis to select the SST analysis optimized for application to the seas around the Korean Peninsula
We evaluated the accuracy of, and performed inter-comparison between, seven Level 4 (L4) global, gap-free, gridded, and daily SST products available for the seas around the Korean Peninsula, for the period of 2014–2018

Summary

Introduction

Sea surface temperature (SST) is a major oceanic variable that plays an important role as an indicator of climate change and as input data for the numerical models used for weather forecasting and oceanic circulation prediction [1,2,3,4]. For nearly half the century, SST was extensively and periodically observed globally, using various satellites [16]. In the case of the L2 SST, the accuracy assessments were conducted in the global oceans [17,18,19,20,21,22], and in the coastal region [23,24,25,26,27]. Since the oceanographic features at the coastal regions have relatively small spatial scales and high variability, as compared to those in the open ocean, validation studies using extensive in-situ temperatures should be performed. Studies have been proposed to develop an instrument that can compensate for the limitations of coastal observations and evaluate the accuracy of satellite

Objectives

Results

Discussion

Conclusion