Application of the Geostationary Ocean Color Imager to Mapping the Diurnal and Seasonal Variability of Surface Suspended Matter in a Macro-Tidal Estuary

Jianhua Gao,Xiao Wang,Zhixin Cheng,David Paull

doi:10.3390/rs8030244

Jianhua Gao, Xiao Wang + Show 2 more

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https://doi.org/10.3390/rs8030244

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Abstract

Total suspended particulate matter (TSM) in estuarine and coastal regions usually exhibits significant natural variations. The understanding of such variations is of great significance in coastal waters. The aim of this study is to investigate and assess the diurnal and seasonal variations of surface TSM distribution and its mechanisms in coastal waters based on Geostationary Ocean Color Imager (GOCI) data. As a case study, dynamic variations of TSM in the macro-tidal Yalu River estuary (YRE) of China were analysed. With regard to diurnal variability, there were usually two peaks of TSM in a tidal cycle corresponding to the maximum flood and ebb current. Tidal action appears to play a vital role in diurnal variations of TSM. Both the processes of tidal re-suspension and advection could be identified; however, the diurnal variation of TSM was mainly affected by a re-suspension process. In addition, spring-neap tides can affect the magnitude of TSM diurnal variations in the YRE. The GOCI-retrieved TSM results clearly showed the seasonal variability of surface TSM in this area, with the highest level occurring in winter and the lowest in summer. Moreover, although river discharge to the YRE was much greater in the wet season than the dry season, TSM concentrations were significantly higher in the dry season. Wind waves were considered to be the main factor affecting TSM seasonal variation in the YRE.

Highlights

Estuaries are vital links between catchments and coastal waters; they contain high concentrations of total suspended particulate matter (TSM) and are characterized by complicated hydrodynamics and environmental systems affected simultaneously by physical, biogeochemical and human activities.Estuaries, are amongst the most complicated of natural systems [1]
TSM hourly maps in the Yalu River estuary (YRE) were derived from Geostationary Ocean Color Imager (GOCI)-retrieved Rrs from cloud-free days throughout 2014, with Figures 3 and 4 showing the hourly TSM maps and corresponding tidal elevation for 3 April and 2 August of that year, respectively
Results and Discussion the turbidity maxima (TM) zone was broadly distributed (Figure 3); this corresponded to the time when a strong ebb tide took place (Figure 3)

Summary

Introduction

Estuaries are vital links between catchments and coastal waters; they contain high concentrations of total suspended particulate matter (TSM) and are characterized by complicated hydrodynamics and environmental systems affected simultaneously by physical, biogeochemical and human activities.Estuaries, are amongst the most complicated of natural systems [1]. Estuaries are vital links between catchments and coastal waters; they contain high concentrations of total suspended particulate matter (TSM) and are characterized by complicated hydrodynamics and environmental systems affected simultaneously by physical, biogeochemical and human activities. Sea surface TSM exhibits significant diurnal and seasonal variability in estuarine regions that can influence the available light underwater and affect the productivity of upper-layer phytoplankton [2,3]. Sedimentary processes in coastal waters can provide nutrients to neighbouring sea areas and affect the transport of carbon, pollutants and other materials [4,5,6]. Monitoring dynamic variations of surface TSM concentrations in estuaries is of great significance, as it can provide a key to understanding sedimentary processes in coastal waters.

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