## 5 Conclusions
* [20] [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON] _SMAP Enhanced L3 Radiometer Global and Polar Grid Daily 9 km EASE-Grid Soil Moisture, Version 5 [Data Set]_; NASA National Snow and Ice Data Center Distributed Active Archive Center: Boulder, CO, USA, 2021; Available online: [[https://nsidc.org/data/spl3](https://nsidc.org/data/spl3) smp_e/versions/5]([https://nsidc.org/data/spl3](https://nsidc.org/data/spl3) smp_e/versions/5) (accessed on 21 January 2022). * [21] [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON] _Soil Moisture Active Passive (SMAP) Algorithm Theoretical Basis Document: Level 2 & 3 Soil Moisture (Passive) Data Products_; Jet Propulsion Laboratory, California Institute of Technology: Pasadena, CA, USA, 2014. Available online: [[https://smap.jpl.nasa.gov/system/internal_resources/details/original/484_L2_SM_P_ATBD_rev_D_Jun2018.pdf](https://smap.jpl.nasa.gov/system/internal_resources/details/original/484_L2_SM_P_ATBD_rev_D_Jun2018.pdf)]([https://smap.jpl.nasa.gov/system/internal_resources/details/original/484_L2_SM_P_ATBD_rev_D_Jun2018.pdf](https://smap.jpl.nasa.gov/system/internal_resources/details/original/484_L2_SM_P_ATBD_rev_D_Jun2018.pdf)) (accessed on 16 June 2021). * [22] [PERSON]; [PERSON]; [PERSON]; [PERSON], [PERSON] High-Resolution Mapping of Global Surface Water and Its Long-Term Changes. _Nature_**2016**, _540_, 418-422. [CrossRef] [PubMed]
* [23] [PERSON]; [PERSON] Passive Microwave Remote Sensing of Soil Moisture. _J. Hydrol._**1996**, _184_, 101-129. [CrossRef]
* [24] [PERSON] _NASA/GSFC/HSL (2018), FLDAS Noah Land Surface Model L4 Global Monthly 0.1 \(\times\) 0.1 Degree (MERRA-2 and CHIRPS) [Data Set]_; Goddard Earth Sciences Data and Information Services Center (GES DISC): Greenbelt, MD, USA, 2018. Available online: [[https://disc.gsfc.nasa.gov/datasets/FLDAS_NOAH01_C_GL_M_001/summary](https://disc.gsfc.nasa.gov/datasets/FLDAS_NOAH01_C_GL_M_001/summary)]([https://disc.gsfc.nasa.gov/datasets/FLDAS_NOAH01_C_GL_M_001/summary](https://disc.gsfc.nasa.gov/datasets/FLDAS_NOAH01_C_GL_M_001/summary)) (accessed on 10 June 2022). * [25] [PERSON] MOD13C2 MODIS/Terra Vegetation Indices Monthly L3 Global 0.05 Deg CMG V006 [Data Set]. NASA EOSDIS Land Processes DAAC. 2015. Available online: [[https://lpdaac.usgs.gov/products/mod13c2v006/](https://lpdaac.usgs.gov/products/mod13c2v006/)]([https://lpdaac.usgs.gov/products/mod13c2v006/](https://lpdaac.usgs.gov/products/mod13c2v006/)) (accessed on 14 June 2022). * [26] [PERSON]; [PERSON]; [PERSON]; [PERSON] Hole-Filled SRTM for the Globe Version 4 [Data Set]. CGIAR-CSI SRTM 90m Database. 2008. Available online: [[http://strm.csi.cgiar.org](http://strm.csi.cgiar.org)]([http://strm.csi.cgiar.org](http://strm.csi.cgiar.org)) (accessed on 1 October 2021). * [27] [PERSON]; [PERSON] MCD12C1 MODIS/Terra+Aqua Land Cover Type Yearly L3 Global 0.05 Deg CMG V006 [Data Set]. NASA EOSDIS Land Processes DAAC. 2015. Available online: [[https://lpdaac.usgs.gov/products/mcd12c1v006/](https://lpdaac.usgs.gov/products/mcd12c1v006/)]([https://lpdaac.usgs.gov/products/mcd12c1v006/](https://lpdaac.usgs.gov/products/mcd12c1v006/)) (accessed on 15 March 2022). * [28] [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] A New Paradigm in Earth Environmental Monitoring with the CYGNSS Small Satellite Constellation. _Sci. Rep._**2018**, \(8\), 1-13. [CrossRef]
* [29] [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] _SMAP L3 Radar/Radiometer Global Daily 9 km EASE-Grid Soil Moisture, Version 3 [Data Set]_; NASA National Snow and Ice Data Center Distributed Active Archive Center: Boulder, CO, USA, 2016; Available online: [[https://nsidc.org/data/spl3](https://nsidc.org/data/spl3) smap/versions/3]([https://nsidc.org/data/spl3](https://nsidc.org/data/spl3) smap/versions/3) (accessed on 19 May 2022). * [30] [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] On the Relationship Between Radar Backscatter and Radiometer Brightness Temperature From SMAP. _IEEE Trans. Geosci.