Effect of surface temperature on soil moisture retrieval using CYGNSS
In this paper, a soil moisture (SM) retrieval model from spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) observations that incorporates soil surface temperature (SST) for the first time is evaluated. Here, based on the grid scale, Cyclone GNSS (CYGNSS) reflectivity, SST and vege...
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| Format: | Article |
| Language: | English |
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Elsevier
2022-08-01
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| Series: | International Journal of Applied Earth Observations and Geoinformation |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1569843222001273 |
| _version_ | 1828758486692921344 |
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| author | Yifan Zhu Fei Guo Xiaohong Zhang |
| author_facet | Yifan Zhu Fei Guo Xiaohong Zhang |
| author_sort | Yifan Zhu |
| collection | DOAJ |
| description | In this paper, a soil moisture (SM) retrieval model from spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) observations that incorporates soil surface temperature (SST) for the first time is evaluated. Here, based on the grid scale, Cyclone GNSS (CYGNSS) reflectivity, SST and vegetation optical depth (VOD) are employed to estimate SM by a trilinear regression, while the other influence factors such as soil roughness and texture are regard as static. The results are compared with globally Soil Moisture Active Passive (SMAP) SM and in-situ measurements from International Soil Moisture Network (ISMN) over the year of 2018 respectively, showing a good consistency (R = 0.929 and RMSE = 0.043 cm3cm−3 against SMAP SM; R = 0.927 and RMSE = 0.042 cm3cm−3 against in-situ SM). Although the sensitivity of reflectivity to SST is found to be much smaller than that to SM from the simulation, the incorporation of SST is demonstrated to be effective in SM estimation for its coupling relationship with SM. In the comparison with SMAP SM, the improvements of RMSE by incorporating SST are varying degrees globally, and significant in many arid areas with an improvement of over 40%. In the in-situ validation, the overall RMSE decreases from 0.047 to 0.042 cm3cm−3 with an improvement of 10.6%. This work demonstrates the necessity and improvement for incorporating SST into SM retrieval for GNSS-R. Moreover, the findings provide a potential method to obtain global SST dataset from CYGNSS observations. |
| first_indexed | 2024-12-11T00:42:44Z |
| format | Article |
| id | doaj.art-09c373d93ca64d3eb75e57b058b34b7e |
| institution | Directory Open Access Journal |
| issn | 1569-8432 |
| language | English |
| last_indexed | 2024-12-11T00:42:44Z |
| publishDate | 2022-08-01 |
| publisher | Elsevier |
| record_format | Article |
| series | International Journal of Applied Earth Observations and Geoinformation |
| spelling | doaj.art-09c373d93ca64d3eb75e57b058b34b7e2022-12-22T01:26:52ZengElsevierInternational Journal of Applied Earth Observations and Geoinformation1569-84322022-08-01112102929Effect of surface temperature on soil moisture retrieval using CYGNSSYifan Zhu0Fei Guo1Xiaohong Zhang2School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, ChinaSchool of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China; Corresponding author.School of Geodesy and Geomatics, Wuhan University, Wuhan 430079, China; Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, Wuhan 430079, China; Collaborative Innovation Center for Geospatial Technology, Wuhan 430079, ChinaIn this paper, a soil moisture (SM) retrieval model from spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) observations that incorporates soil surface temperature (SST) for the first time is evaluated. Here, based on the grid scale, Cyclone GNSS (CYGNSS) reflectivity, SST and vegetation optical depth (VOD) are employed to estimate SM by a trilinear regression, while the other influence factors such as soil roughness and texture are regard as static. The results are compared with globally Soil Moisture Active Passive (SMAP) SM and in-situ measurements from International Soil Moisture Network (ISMN) over the year of 2018 respectively, showing a good consistency (R = 0.929 and RMSE = 0.043 cm3cm−3 against SMAP SM; R = 0.927 and RMSE = 0.042 cm3cm−3 against in-situ SM). Although the sensitivity of reflectivity to SST is found to be much smaller than that to SM from the simulation, the incorporation of SST is demonstrated to be effective in SM estimation for its coupling relationship with SM. In the comparison with SMAP SM, the improvements of RMSE by incorporating SST are varying degrees globally, and significant in many arid areas with an improvement of over 40%. In the in-situ validation, the overall RMSE decreases from 0.047 to 0.042 cm3cm−3 with an improvement of 10.6%. This work demonstrates the necessity and improvement for incorporating SST into SM retrieval for GNSS-R. Moreover, the findings provide a potential method to obtain global SST dataset from CYGNSS observations.http://www.sciencedirect.com/science/article/pii/S1569843222001273Soil moisture (SM)Soil surface temperature (SST)Global Navigation Satellite System Reflectometry (GNSS-R)Cyclone Global Navigation Satellite System (CYGNSS) |
| spellingShingle | Yifan Zhu Fei Guo Xiaohong Zhang Effect of surface temperature on soil moisture retrieval using CYGNSS International Journal of Applied Earth Observations and Geoinformation Soil moisture (SM) Soil surface temperature (SST) Global Navigation Satellite System Reflectometry (GNSS-R) Cyclone Global Navigation Satellite System (CYGNSS) |
| title | Effect of surface temperature on soil moisture retrieval using CYGNSS |
| title_full | Effect of surface temperature on soil moisture retrieval using CYGNSS |
| title_fullStr | Effect of surface temperature on soil moisture retrieval using CYGNSS |
| title_full_unstemmed | Effect of surface temperature on soil moisture retrieval using CYGNSS |
| title_short | Effect of surface temperature on soil moisture retrieval using CYGNSS |
| title_sort | effect of surface temperature on soil moisture retrieval using cygnss |
| topic | Soil moisture (SM) Soil surface temperature (SST) Global Navigation Satellite System Reflectometry (GNSS-R) Cyclone Global Navigation Satellite System (CYGNSS) |
| url | http://www.sciencedirect.com/science/article/pii/S1569843222001273 |
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