Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China
Spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) provides a new opportunity for land observation. This study is the first to compare and evaluate the performance of the only two spaceborne GNSS-R satellite missions whose data are publicly available, i.e., the UK’s TechdemoSat-1 (...
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MDPI AG
2020-05-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/12/11/1699 |
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| author | Ting Yang Wei Wan Zhigang Sun Baojian Liu Sen Li Xiuwan Chen |
| author_facet | Ting Yang Wei Wan Zhigang Sun Baojian Liu Sen Li Xiuwan Chen |
| author_sort | Ting Yang |
| collection | DOAJ |
| description | Spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) provides a new opportunity for land observation. This study is the first to compare and evaluate the performance of the only two spaceborne GNSS-R satellite missions whose data are publicly available, i.e., the UK’s TechdemoSat-1 (TDS-1) and the US’s Cyclone Global Navigation Satellite System (CYGNSS), for sensitivity analysis with SMAP SM on a daily basis and soil moisture (SM) estimates on a monthly basis over Mainland China. For daily sensitivity analysis, the two data were matched up and compared for the period (i.e., May 2017 through April 2018) when they coexisted (R = 0.561 vs. R = 0.613). For monthly SM estimates, a back-propagation artificial neural network (BP-ANN) was used to construct a model using data from more than two years. The model was subsequently used to derive long-term and continuous SM maps over Mainland China. The results showed that TDS-1 and CYGNSS agree and correlate very well with the SMAP SM in Mainland China (R = 0.676, MAE = 0.052 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.060 m<sup>3</sup>m<sup>−3</sup> for TDS-1; R = 0.798, MAE = 0.040 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.062 m<sup>3</sup>m<sup>−3</sup> for CYGNSS). The retrieved results were further validated using monthly in situ SM data from dense sites across Mainland China. It was found that the SM derived from the TDS-1/CYGNSS also correlated well with in situ SM (R = 0.687, MAE = 0.066 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.056 m<sup>3</sup>m<sup>−3</sup> for TDS-1; R = 0.724, MAE = 0.052 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.053 m<sup>3</sup>m<sup>−3</sup> for CYGNSS). The results in this study suggested that TDS-1/CYGNSS and the upcoming spaceborne GNSS-R mission could be new and powerful data sources to produce SM data set at a large scale and with relatively high precision. |
| first_indexed | 2024-03-10T19:34:49Z |
| format | Article |
| id | doaj.art-838da25fcad847afa7fb6c83c9164ded |
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| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T19:34:49Z |
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| spelling | doaj.art-838da25fcad847afa7fb6c83c9164ded2023-11-20T01:47:12ZengMDPI AGRemote Sensing2072-42922020-05-011211169910.3390/rs12111699Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland ChinaTing Yang0Wei Wan1Zhigang Sun2Baojian Liu3Sen Li4Xiuwan Chen5CAS Engineering Laboratory for Yellow River Delta Modern Agriculture, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaInstitute of Remote Sensing and GIS, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaCAS Engineering Laboratory for Yellow River Delta Modern Agriculture, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, ChinaInstitute of Remote Sensing and GIS, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaNational Meteorological Center, China Meteorological Administration, Beijing 100081, ChinaInstitute of Remote Sensing and GIS, School of Earth and Space Sciences, Peking University, Beijing 100871, ChinaSpaceborne Global Navigation Satellite System Reflectometry (GNSS-R) provides a new opportunity for land observation. This study is the first to compare and evaluate the performance of the only two spaceborne GNSS-R satellite missions whose data are publicly available, i.e., the UK’s TechdemoSat-1 (TDS-1) and the US’s Cyclone Global Navigation Satellite System (CYGNSS), for sensitivity analysis with SMAP SM on a daily basis and soil moisture (SM) estimates on a monthly basis over Mainland China. For daily sensitivity analysis, the two data were matched up and compared for the period (i.e., May 2017 through April 2018) when they coexisted (R = 0.561 vs. R = 0.613). For monthly SM estimates, a back-propagation artificial neural network (BP-ANN) was used to construct a model using data from more than two years. The model was subsequently used to derive long-term and continuous SM maps over Mainland China. The results showed that TDS-1 and CYGNSS agree and correlate very well with the SMAP SM in Mainland China (R = 0.676, MAE = 0.052 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.060 m<sup>3</sup>m<sup>−3</sup> for TDS-1; R = 0.798, MAE = 0.040 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.062 m<sup>3</sup>m<sup>−3</sup> for CYGNSS). The retrieved results were further validated using monthly in situ SM data from dense sites across Mainland China. It was found that the SM derived from the TDS-1/CYGNSS also correlated well with in situ SM (R = 0.687, MAE = 0.066 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.056 m<sup>3</sup>m<sup>−3</sup> for TDS-1; R = 0.724, MAE = 0.052 m<sup>3</sup>m<sup>−3</sup>, and ubRMSE = 0.053 m<sup>3</sup>m<sup>−3</sup> for CYGNSS). The results in this study suggested that TDS-1/CYGNSS and the upcoming spaceborne GNSS-R mission could be new and powerful data sources to produce SM data set at a large scale and with relatively high precision.https://www.mdpi.com/2072-4292/12/11/1699soil moisture (SM)CYGNSSTDS-1GNSS-Rmainland China |
| spellingShingle | Ting Yang Wei Wan Zhigang Sun Baojian Liu Sen Li Xiuwan Chen Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China Remote Sensing soil moisture (SM) CYGNSS TDS-1 GNSS-R mainland China |
| title | Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China |
| title_full | Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China |
| title_fullStr | Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China |
| title_full_unstemmed | Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China |
| title_short | Comprehensive Evaluation of Using TechDemoSat-1 and CYGNSS Data to Estimate Soil Moisture over Mainland China |
| title_sort | comprehensive evaluation of using techdemosat 1 and cygnss data to estimate soil moisture over mainland china |
| topic | soil moisture (SM) CYGNSS TDS-1 GNSS-R mainland China |
| url | https://www.mdpi.com/2072-4292/12/11/1699 |
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