Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula
In the last decade, technological advances led to the launch of two satellite missions dedicated to measure the Earth's surface soil moisture (SSM): the ESA's Soil Moisture and Ocean Salinity (SMOS) launched in 2009, and the NASA's Soil Moisture Active Passive (SMAP) launched in 2015....
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2020
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| Online Access: | https://hdl.handle.net/1721.1/125194 |
| _version_ | 1826188968982478848 |
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| author | Portal, Gerard Jagdhuber, Thomas Vall-llossera, Mercè Camps, Adriano Pablos, Miriam Entekhabi, Dara Piles, Maria |
| author2 | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Civil and Environmental Engineering Portal, Gerard Jagdhuber, Thomas Vall-llossera, Mercè Camps, Adriano Pablos, Miriam Entekhabi, Dara Piles, Maria |
| author_sort | Portal, Gerard |
| collection | MIT |
| description | In the last decade, technological advances led to the launch of two satellite missions dedicated to measure the Earth's surface soil moisture (SSM): the ESA's Soil Moisture and Ocean Salinity (SMOS) launched in 2009, and the NASA's Soil Moisture Active Passive (SMAP) launched in 2015. The two satellites have an L-band microwave radiometer on-board to measure the Earth's surface emission. These measurements (brightness temperatures TB) are then used to generate global maps of SSM every three days with a spatial resolution of about 30-40 km and a target accuracy of 0.04 m3/m3. To meet local applications needs, different approaches have been proposed to spatially disaggregate SMOS and SMAP TB or their SSM products. They rely on synergies between multi-sensor observations and are built upon different physical assumptions. In this study, temporal and spatial characteristics of six operational SSM products derived from SMOS and SMAP are assessed in order to diagnose their distinct features, and the rationale behind them. The study is focused on the Iberian Peninsula and covers the period from April 2015 to December 2017. A temporal inter-comparison analysis is carried out using in situ SSM data from the Soil Moisture Measurements Station Network of the University of Salamanca (REMEDHUS) to evaluate the impact of the spatial scale of the different products (1, 3, 9, 25, and 36 km), and their correspondence in terms of temporal dynamics. A spatial analysis is conducted for the whole Iberian Peninsula with emphasis on the added-value that the enhanced resolution products provide based on the microwave-optical (SMOS/ERA5/MODIS) or the active-passive microwave (SMAP/Sentinel-1) sensor fusion. Our results show overall agreement among time series of the products regardless their spatial scale when compared to in situ measurements. Still, higher spatial resolutions would be needed to capture local features such as small irrigated areas that are not dominant at the 1-km pixel scale. The degree to which spatial features are resolved by the enhanced resolution products depend on the multi-sensor synergies employed (at TB or soil moisture level), and on the nature of the fine-scale information used. The largest disparities between these products occur in forested areas, which may be related to the reduced sensitivity of high-resolution active microwave and optical data to soil properties under dense vegetation. Keywords: soil moisture; moisture variability; temporal dynamics; moisture patterns; spatial disaggregation; Soil Moisture Active Passive (SMAP); Soil Moisure and Ocean Salinity (SMOS); REMEDHUS |
| first_indexed | 2024-09-23T08:07:30Z |
| format | Article |
| id | mit-1721.1/125194 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:07:30Z |
| publishDate | 2020 |
| publisher | MDPI AG |
| record_format | dspace |
| spelling | mit-1721.1/1251942022-09-23T11:04:18Z Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula Portal, Gerard Jagdhuber, Thomas Vall-llossera, Mercè Camps, Adriano Pablos, Miriam Entekhabi, Dara Piles, Maria Massachusetts Institute of Technology. Department of Civil and Environmental Engineering In the last decade, technological advances led to the launch of two satellite missions dedicated to measure the Earth's surface soil moisture (SSM): the ESA's Soil Moisture and Ocean Salinity (SMOS) launched in 2009, and the NASA's Soil Moisture Active Passive (SMAP) launched in 2015. The two satellites have an L-band microwave radiometer on-board to measure the Earth's surface emission. These measurements (brightness temperatures TB) are then used to generate global maps of SSM every three days with a spatial resolution of about 30-40 km and a target accuracy of 0.04 m3/m3. To meet local applications needs, different approaches have been proposed to spatially disaggregate SMOS and SMAP TB or their SSM products. They rely on synergies between multi-sensor observations and are built upon different physical assumptions. In this study, temporal and spatial characteristics of six operational SSM products derived from SMOS and SMAP are assessed in order to diagnose their distinct features, and the rationale behind them. The study is focused on the Iberian Peninsula and covers the period from April 2015 to December 2017. A temporal inter-comparison analysis is carried out using in situ SSM data from the Soil Moisture Measurements Station Network of the University of Salamanca (REMEDHUS) to evaluate the impact of the spatial scale of the different products (1, 3, 9, 25, and 36 km), and their correspondence in terms of temporal dynamics. A spatial analysis is conducted for the whole Iberian Peninsula with emphasis on the added-value that the enhanced resolution products provide based on the microwave-optical (SMOS/ERA5/MODIS) or the active-passive microwave (SMAP/Sentinel-1) sensor fusion. Our results show overall agreement among time series of the products regardless their spatial scale when compared to in situ measurements. Still, higher spatial resolutions would be needed to capture local features such as small irrigated areas that are not dominant at the 1-km pixel scale. The degree to which spatial features are resolved by the enhanced resolution products depend on the multi-sensor synergies employed (at TB or soil moisture level), and on the nature of the fine-scale information used. The largest disparities between these products occur in forested areas, which may be related to the reduced sensitivity of high-resolution active microwave and optical data to soil properties under dense vegetation. Keywords: soil moisture; moisture variability; temporal dynamics; moisture patterns; spatial disaggregation; Soil Moisture Active Passive (SMAP); Soil Moisure and Ocean Salinity (SMOS); REMEDHUS Sobre la continuidad de las misiones satelitales debanda L. Nuevos paradigmas en productos y aplicaciones, grant numbers ESP2017-89463-C3-2-R (UPC part) andESP2017-89463-C3-1-R (ICM part) Unidad de Excelencia María de Maeztu MDM-2016-0600 2020-05-12T20:46:11Z 2020-05-12T20:46:11Z 2020-02 2020-02 2020-05-11T18:48:08Z Article http://purl.org/eprint/type/JournalArticle 2072-4292 https://hdl.handle.net/1721.1/125194 Portal, Gerard, et al. "Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula." Remote Sensing, 12, 3 (February 2020): 570. © 2020 The Author(s). en http://dx.doi.org/10.3390/rs12030570 Remote Sensing Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf MDPI AG MDPI |
| spellingShingle | Portal, Gerard Jagdhuber, Thomas Vall-llossera, Mercè Camps, Adriano Pablos, Miriam Entekhabi, Dara Piles, Maria Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula |
| title | Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula |
| title_full | Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula |
| title_fullStr | Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula |
| title_full_unstemmed | Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula |
| title_short | Assessment of Multi-Scale SMOS and SMAP Soil Moisture Products across the Iberian Peninsula |
| title_sort | assessment of multi scale smos and smap soil moisture products across the iberian peninsula |
| url | https://hdl.handle.net/1721.1/125194 |
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