Sentinel-3A SRAL Global Statistical Assessment and Cross-Calibration with Jason-3

Jungang Yang,Jie Zhang,Changying Wang

doi:10.3390/rs11131573

Abstract

The Sentinel-3A satellite, equipped with Synthetic Aperture Radar (SAR) Altimeter (SRAL) instrument to derive sea surface height, significant wave height and surface wind speed over the global ocean, was launched on 16 February 2016. The assessment of data quality and the system performance of the altimeter are very important to data application. In this article, Sentinel-3A SRAL data quality is assessed and altimetry system performance is estimated by verifying data availability and monitoring the parameters of altimeter and radiometer through the global statistical analyses of Sentinel-3A Non-Time-Critical (NTC) Marine Level 2 products during the period from 13 March 2016 to 25 February 2019, in comparison with self-crossovers and cross-calibration with the Jason-3 mission. The global statistical analyses and the comparisons at self-crossovers show that Sentinel-3A SRAL data and performance are stable and have no trend over time, and the total cycle average root mean square errors (RMSEs) of sea surface height (SSH) differences at self-crossovers is about 5.4 cm. The comparisons at the dual-crossovers show the consistency of the observation between Sentinel-3A SRAL and Jason-3, and indicate that the systemic bias of SSH is about 2.96 cm. In general, it can be concluded that Sentinel-3A SRAL has good and stable data quality and system performance for operational ocean forecasting and scientific research.

Highlights

Sentinel-3 is an Earth observation satellite mission of the Copernicus programme which, previously known as GMES (Global Monitoring for Environment and Security), is the European Programme for the establishment of a European capacity for Earth Observation
The Ocean Validation reports summarize validation results obtained from SAR Altimeter (SRAL)/Sentinel-3 STC Marine Level 2 products processed by the Marine Centre by monitoring the following parameters: Sea Level Anomaly (SLA), Significant Wave Height, Backscattering Coefficient, and Altimeter Wind Speed [13]
The analysis of the edited measurement of Sentinel-3A SRAL can validate the availability of Sentinel-3A SRAL data

Summary

Introduction

Sentinel-3 is an Earth observation satellite mission of the Copernicus programme which, previously known as GMES (Global Monitoring for Environment and Security), is the European Programme for the establishment of a European capacity for Earth Observation. The reports summarize the assessment of the altimetry mission, split per instrument, or thematic topic: SRAL, MWR, Ocean Validation, Winds & Waves, and Land & Sea Ice. The Ocean Validation reports summarize validation results obtained from SRAL/Sentinel-3 STC Marine Level 2 products processed by the Marine Centre by monitoring the following parameters: Sea Level Anomaly (SLA), Significant Wave Height, Backscattering Coefficient, and Altimeter Wind Speed [13]. This paper focuses on the long-term monitoring of the Sentinel-3A SRAL system over the ocean It includes continuous monitoring of altimeter and radiometer parameters, performance assessment, geophysical evaluation, and cross-calibration with Jason-3 measurements, which are not conducted in the routine validation work of Sentinel-3A SRAL.

Sentinel-3A Data

Jason-3 Data

Results and Discussion

Edited Measurements

Comparisons at Self-Crossovers