Improvement of Sea Surface Height Measurements of HY-2A Satellite Altimeter Using Jason-2

Abstract

HY-2A, which was launched on 16 August 2011, is the Chinese first microwave ocean dynamics environment satellite. Analyses of HY-2A daily sea-level anomaly data and HY-2A–Jason-2 (H-J) dual crossover sea-level anomaly differences show that HY-2A has measurement differences that mainly refer to an orbit error. H-J crossover differences and HY-2A–HY-2A (H-H) crossover differences give an estimate of the HY-2A orbit error. Smoothing cubic-spline functions are then used to obtain a continuous estimation of the HY-2A orbit error over time. On the basis of the simultaneous global minimization of H-J dual crossover differences and H-H crossover differences, the HY-2A observation error is efficiently reduced and height measurement data that are more precise are obtained. Specifically, the range bias/trend of the HY-2A altimeter is removed effectively and the root mean square of H-J crossover sea-level anomaly differences decrease from above 60 cm to 5.64 cm, and the standard deviation of H-J crossover differences decreases from 6.68 to 5.64 cm. Furthermore, the rms and standard deviations of H-H crossover differences both decrease from 7.46 to 6.55 cm. The results show that HY-2A after correction has a measurement accuracy and precision that are comparable to those of Jason-2.

Keywords:

• crossover analysis
• HY-2A satellite altimeter
• measurement accuracy
• sea surface height
• the orbit error correction

Disclosure statement

No potential conflict of interest was reported by the authors.

Acknowledgements

The authors would thank the National Satellite Ocean Application Service, State Oceanic Administration for providing HY-2A IGDR products (http://www.nsoas.gov.cn or http://ftp://114.255.97.103) and NOAA for providing Jason-2 GDR products (https://www.nodc.noaa.gov/SatelliteData/)

Additional information

Funding

This study is supported by the National Key R&D Program of China (2016YFC1401800), the National Natural Science Foundation of China (No.41576176), Dragon 4 Project (ID.32292) and in part of National Programme on Global Change and Air-Sea Interaction (GASI-02-PAC-YGST₂-04, GASI-02-IND-YGST₂-04, GASI-02-SCS-YGST₂-04).