Wet Tropospheric Correction for the HY-2C Altimeter over the Coastal Ocean Based on GNSS and ERA5 Data

Abstract

For the impact of land, sea ice, rainfall and strong wind, the wet tropospheric correction (WTC) of HY-2C (the third marine dynamic environmental monitoring satellite of China) altimeter cannot be obtained accurately by the calibration microwave radiometer (CMR) over the coastal ocean. The conducted evaluation of the HY-2C CMR WTC over the coastal ocean by the Global Navigation Satellite System (GNSS) and ECMWF Reanalysis v5 (ERA5) data showed that the CMR WTC is abnormal or invalid. To solve this issue, a new method to determine the WTC of the HY-2C altimeter based on objective analysis (OA) by combining the GNSS WTC, ERA5 WTC and valid CMR WTC is developed. The OA WTC and HY-2C CMR WTC are compared to the Integrated Global Radiosonde Archive (IGRA) WTC to validate the OA method. The results show that the RMSE of the WTC differences significantly decreases and the correlation coefficient increases. The number of available WTC data increases over the open ocean. The variances of sea level anomaly corresponding to the OA WTC in most areas are significantly smaller than those of the HY-2C CMR WTC. In general, the availability and accuracy of HY-2C altimeter data are largely enhanced with the OA WTC.

Keywords:

• HY-2C
• altimeter
• wet tropospheric correction
• GNSS
• ERA5

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author.

Additional information

Funding

This work was funded by the National Key R&D Program of China (grant number 2022YFC3104900 and 2022YFC3104902), the National Natural Science Foundation of China (No.62231028), Dragon 5 Project (ID.58900), the Natural Science Foundation of Shandong Province (No. ZR2022MD002) and the Marine Project 2205cxzx040431. The HY-2C altimeter data are provided by National Satellite Ocean Application Service. The GNSS data are provided by NASA and IGS Data Center of Wuhan University. The ERA5 data are provided by ECMWF. The IGRA data are provided by NCDC.