Coastal Mean Dynamic Topography Recovery Based on Multivariate Objective Analysis by Combining Data from Synthetic Aperture Radar Altimeter

Yihao Wu,Xiufeng He,Jia Huang,Zhicai Luo,Haihong Wang

doi:10.3390/rs14010240

Abstract

MDT recovery over coastal regions is challenging, as the mean sea surface (MSS) and geoid/quasi-geoid models are of low quality. The altimetry satellites equipped with the synthetic aperture radar (SAR) altimeters provide more accurate sea surface heights than traditional ones close to the coast. We investigate the role of using the SAR-based MSS in coastal MDT recovery, and the effects introduced by the SAR altimetry data are quantified and assessed. We model MDTs based on the multivariate objective analysis, where the MSS and the recently released satellite-only global geopotential model are combined. The numerical experiments over the coast of Japan and southeastern China show that the use of the SAR-based MSS improves the local MDT. The root mean square (RMS) of the misfits between MDT-modeled with SAR altimetry data and the ocean data is lower than that derived from MDT computed without SAR data—by a magnitude of 4–8 mm. Moreover, the geostrophic velocities derived from MDT modeled with the SAR altimetry data have better fits with buoy data than those derived from MDT modeled without SAR data. In total, our studies highlight the use of SAR altimetry data in coastal MDT recovery.

Highlights

The information of coastal mean dynamic topography (MDT) plays an important role in disciplines such as oceanography and climatology
We model the local MDT based on the multivariate objective analysis (MOA) method, by which the mean sea surface and geoid/quasi-geoid models are combined
Derived from DTU21MSS is 9 mm, while the root mean square (RMS) of the formal errors of MDT derived from DTU15MSS/DTU18MSS is 16/13 mm, which is slightly larger. These results show that the use of the mean sea surface model computed with high-quality synthetic aperture radar (SAR) altimetry data can improve MDT modeling over coastal regions, which may improve the coast MDT by a magnitude of several millimeters, compared to MDT computed with the mean sea surface model without SAR altimetry data

Summary

Introduction

The information of coastal mean dynamic topography (MDT) plays an important role in disciplines such as oceanography and climatology. MDT information is crucial for studying sea level change and climate change. The geostrophic current velocity can be obtained from the first derivatives of MDT, which is useful for understanding heat and energy transport mechanisms over offshore regions [1,2,3]. The accurate MDT model facilitates the unification of land—sea vertical data [4,5,6]. The knowledge of coastal MDT facilitates human activities such as fishing and oil/gas explorations, economic development, and offshore engineering construction [7]. MDT influences coastal carbon cycling, salinization of freshwater systems, and the marine ecological environment [8]. MDT affects the coastline change and coastal erosion [9], and it can provide a scientific decision basis for environmental protection and management over coastal areas [10]

Methods

Results

Conclusion