Vertical Deflections and Gravity Disturbances Derived from HY-2A Data
The first Chinese altimetry satellite, Haiyang-2A (HY-2A), which was launched in 2011, has provided a large amount of sea surface heights which can be used to derive marine gravity field. This paper derived the vertical deflections and gravity disturbances using HY-2A observations for the major area...
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doaj-36111afd81ca42798bdb3d1c89b9d8bd2020-11-25T03:33:42ZengMDPI AGRemote Sensing2072-42922020-07-01122287228710.3390/rs12142287Vertical Deflections and Gravity Disturbances Derived from HY-2A DataXiaoyun Wan0Richard Fiifi Annan1Shuanggen Jin2Xiaoqi Gong3School of Land Science and Technology, China University of Geosciences (Beijing), Beijing 100083, ChinaSchool of Land Science and Technology, China University of Geosciences (Beijing), Beijing 100083, ChinaSchool of Remote Sensing and Geomatics Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaSchool of Land Science and Technology, China University of Geosciences (Beijing), Beijing 100083, ChinaThe first Chinese altimetry satellite, Haiyang-2A (HY-2A), which was launched in 2011, has provided a large amount of sea surface heights which can be used to derive marine gravity field. This paper derived the vertical deflections and gravity disturbances using HY-2A observations for the major area of the whole Earth’s ocean from 60°S and 60°N. The results showed that the standard deviations (STD) of vertical deflections were 1.1 s and 3.5 s for the north component and the east component between HY-2A’s observations and those from EGM2008 and EIGEN-6C4, respectively. This indicates the accuracy of the east component was poorer than that of the north component. In order to clearly demonstrate contribution of HY-2A’s observations to gravity disturbances, reference models and the commonly used remove-restore method were not adopted in this study. Therefore, the results can be seen as ‘pure’ signals from HY-2A. Assuming the values from EGM2008 were the true values, the accuracy of the gravity disturbances was about −1.1 mGal in terms of mean value of the errors and 8.0 mGal in terms of the STD. This shows systematic errors if only HY-2A observations were used. An index of STD showed that the accuracy of HY-2A was close to the theoretical accuracy according to the vertical deflection products. To verify whether the systematic errors of gravity field were from the long wavelengths, the long-wavelength parts of HY-2A’s gravity disturbance with wavelengths larger than 500 km were replaced by those from EGM2008. By comparing with ‘pure’ HY-2A version of gravity disturbance, the accuracy of the new version products was improved largely. The systematic errors no longer existed and the error STD was reduced to 6.1 mGal.https://www.mdpi.com/2072-4292/12/14/2287HY-2Avertical deflectionsgravity disturbanceEGM2008EIGEN-6C4 |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Xiaoyun Wan Richard Fiifi Annan Shuanggen Jin Xiaoqi Gong |
spellingShingle |
Xiaoyun Wan Richard Fiifi Annan Shuanggen Jin Xiaoqi Gong Vertical Deflections and Gravity Disturbances Derived from HY-2A Data Remote Sensing HY-2A vertical deflections gravity disturbance EGM2008 EIGEN-6C4 |
author_facet |
Xiaoyun Wan Richard Fiifi Annan Shuanggen Jin Xiaoqi Gong |
author_sort |
Xiaoyun Wan |
title |
Vertical Deflections and Gravity Disturbances Derived from HY-2A Data |
title_short |
Vertical Deflections and Gravity Disturbances Derived from HY-2A Data |
title_full |
Vertical Deflections and Gravity Disturbances Derived from HY-2A Data |
title_fullStr |
Vertical Deflections and Gravity Disturbances Derived from HY-2A Data |
title_full_unstemmed |
Vertical Deflections and Gravity Disturbances Derived from HY-2A Data |
title_sort |
vertical deflections and gravity disturbances derived from hy-2a data |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2020-07-01 |
description |
The first Chinese altimetry satellite, Haiyang-2A (HY-2A), which was launched in 2011, has provided a large amount of sea surface heights which can be used to derive marine gravity field. This paper derived the vertical deflections and gravity disturbances using HY-2A observations for the major area of the whole Earth’s ocean from 60°S and 60°N. The results showed that the standard deviations (STD) of vertical deflections were 1.1 s and 3.5 s for the north component and the east component between HY-2A’s observations and those from EGM2008 and EIGEN-6C4, respectively. This indicates the accuracy of the east component was poorer than that of the north component. In order to clearly demonstrate contribution of HY-2A’s observations to gravity disturbances, reference models and the commonly used remove-restore method were not adopted in this study. Therefore, the results can be seen as ‘pure’ signals from HY-2A. Assuming the values from EGM2008 were the true values, the accuracy of the gravity disturbances was about −1.1 mGal in terms of mean value of the errors and 8.0 mGal in terms of the STD. This shows systematic errors if only HY-2A observations were used. An index of STD showed that the accuracy of HY-2A was close to the theoretical accuracy according to the vertical deflection products. To verify whether the systematic errors of gravity field were from the long wavelengths, the long-wavelength parts of HY-2A’s gravity disturbance with wavelengths larger than 500 km were replaced by those from EGM2008. By comparing with ‘pure’ HY-2A version of gravity disturbance, the accuracy of the new version products was improved largely. The systematic errors no longer existed and the error STD was reduced to 6.1 mGal. |
topic |
HY-2A vertical deflections gravity disturbance EGM2008 EIGEN-6C4 |
url |
https://www.mdpi.com/2072-4292/12/14/2287 |
work_keys_str_mv |
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