Mapping Diurnal Variability of the Wintertime Pearl River Plume Front from Himawari-8 Geostationary Satellite Observations

Zifeng Hu,Jinchi Xie,Yaping Lei,Jun Zhao,Wenhong Pang,Guanghao Xie

doi:10.3390/w14010043

Abstract

The spatial pattern of the wintertime Pearl River plume front (PRPF), and its variability on diurnal and spring-neap time scales are characterized from the geostationary meteorological Himawari-8 satellite, taking advantage of the satellite’s unique 10-minutely sea surface temperature sequential images. Our findings suggest that the PRPF in winter consists of three subfronts: the northern one north of 22° N 20′, the southern one south of 21° N 40′, and the middle one between 22° N 20′ and 21° N 40′. The time-varying trend of the frontal intensity generally exhibits a strong-weak-strong pattern, with the weakest plume front occurring at about 06:00 UTC, which is closely associated with net surface heat flux over the region. The comparison in frontal variability between the spring and neap tides shows that the plume front during the spring tide generally tends to be more diffuse for the frontal probability, move further offshore for the frontal position, and be weaker for the frontal intensity than those found during the neap tide. These great differences largely depend on the tidally induced stronger turbulent mixing during the spring tide while the wind stress only plays a secondary role in the process. To best of our knowledge, the distinct diurnal variations in PRPF with wide coverage are observed for the first time. This study demonstrates that the Himawari-8 geostationary satellite has great potential in characterizing high-frequency surface thermal fronts in considerable detail.

Highlights

Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Pearl River Estuary Marine Ecosystem Research Station, Ministry of Education, Zhuhai 519000, China
Using a robust edge-detection algorithm, the horizontal structure and diurnal variability of the wintertime Pearl River (PR) thermal plume front during spring and neap tides are for the first time characterized from 10-min sequential SST images of Himawari-8 satellite observations
Our results indicate that the thermal plume front composes of three subfronts: the northern one north of 22◦ N 200, the southern one south of 21◦ N 400 and the middle one between them

Summary

Introduction

Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Pearl River Estuary Marine Ecosystem Research Station, Ministry of Education, Zhuhai 519000, China. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Abstract: The spatial pattern of the wintertime Pearl River plume front (PRPF), and its variability on diurnal and spring-neap time scales are characterized from the geostationary meteorological. The comparison in frontal variability between the spring and neap tides shows that the plume front during the spring tide generally tends to be more diffuse for the frontal probability, move further offshore for the frontal position, and be weaker for the frontal intensity than those found during the neap tide These great differences largely depend on the tidally induced stronger turbulent mixing during the spring tide while the wind stress only plays a secondary role in the process. The dynamics are very active and always accompanied by strong vertical mixing [2,3], which can significantly induce vertical fluxes of heat, salt, and nutrients, thereby stimulating high biological productivity [4,5]

Objectives

Results

Discussion

Conclusion