EAGLE 2006 – Multi-purpose, multi-angle and multi-sensor in-situ and airborne campaigns over grassland and forest

EAGLE2006 - an intensive field campaign - was carried out in the Netherlands from the 8th until the 18th of June 2006. Several airborne sensors - an optical imaging sensor, an imaging microwave radiometer, and a flux airplane – were used and extensive ground measurements were conducted over one grassland (Cabauw) site and two forest sites (Loobos & Speulderbos) in the central part of the Netherlands, in addition to the acquisition of multi-angle and multi-sensor satellite data. The data set is both unique and urgently needed for the development and validation of models and inversion algorithms for quantitative surface parameter estimation and process studies. EAGLE2006 was led by the Department of Water Resources of the International Institute for Geo-Information Science and Earth Observation and originated from the combination of a number of initiatives coming under different funding. The objectives of the EAGLE2006 campaign were closely related to the objectives of other ESA Campaigns (SPARC2004, Sen2Flex2005 and especially AGRISAR2006). However, one important objective of the campaign is to build up a data base for the investigation and validation of the retrieval of bio-geophysical parameters, obtained at different radar frequencies (X-, C- and L-Band) and at hyperspectral optical and thermal bands acquired over vegetated fields (forest and grassland). As such, all activities were related to algorithm development for future satellite missions such as Sentinels and for satellite validations for MERIS, MODIS as well as AATSR and ASTER thermal data validation, with activities also related to the ASAR sensor on board ESA’s Envisat platform and those on EPS/MetOp and SMOS. Most of the activities in the campaign are highly relevant for the EU GEMS EAGLE project, but also issues related to retrieval of biophysical parameters from MERIS and MODIS as well as AATSR and ASTER data were of particular relevance to the NWO-SRON EcoRTM project, while scaling issues and complementary between these (covering only local sites) and global sensors such as MERIS/SEVIRI, EPS/MetOP and SMOS were also key elements for the SMOS cal/val project and the ESA-MOST DRAGON programme. This contribution describes the mission objectives and provides an overview of the airborne and field campaigns

An artificial neural network approach for soil moisture retrieval using passive microwave data

Soil moisture is a key variable that defines land surface-atmosphere (boundary layer) interactions, by contributing directly to the surface energy and water balance. Soil moisture values derived from remote sensing platforms only accounts for the near surface soil layers, generally the top 5cm. Passive microwave data at L-band (1.4 GHz, 21cm wavelength) measurements are shown to be a very effective observation for surface soil moisture retrieval. The first space-borne L-band mission dedicated to observing soil moisture, the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) mission, was launched on 2nd November 2009.Artificial Neural Network (ANN) methods have been used to empirically ascertain the complex statistical relationship between soil moisture and brightness temperature in the presence of vegetation cover. The current problem faced by this method is its inability to predict soil moisture values that are 'out-of-range' of the training data.In this research, an optimization model is developed for the Backpropagation Neural Network model. This optimization model utilizes the combination of the mean and standard deviation of the soil moisture values, together with the prediction process at different pre-determined, equal size regions to cope with the spatial and temporal variation of soil moisture values. This optimized model coupled with an ANN of optimum architecture, in terms of inputs and the number of neurons in the hidden layers, is developed to predict scale-to-scale and downscaling of soil moisture values. The dependency on the accuracy of the mean and standard deviation values of soil moisture data is also studied in this research by simulating the soil moisture values using a multiple regression model. This model obtains very encouraging results for these research problems.The data used to develop and evaluate the model in this research has been obtained from the National Airborne Field Experiments in 2005

2000 days of SMOS at the Barcelona Expert Centre: a tribute to the work of Jordi Font

Soil Moisture and Ocean Salinity (SMOS) is the first satellite mission capable of measuring sea surface salinity and soil moisture from space. Its novel instrument (the L-band radiometer MIRAS) has required the development of new algorithms to process SMOS data, a challenging task due to many processing issues and the difficulties inherent in a new technology. In the wake of SMOS, a new community of users has grown, requesting new products and applications, and extending the interest in this novel brand of satellite services. This paper reviews the role played by the Barcelona Expert Centre under the direction of Jordi Font, SMOS co-principal investigator. The main scientific activities and achievements and the future directions are discussed, highlighting the importance of the oceanographic applications of the mission.Peer ReviewedPostprint (published version

Earth observation-based operational estimation of soil moisture and evapotranspiration for agricultural crops in support of sustainable water management

Global information on the spatio-temporal variation of parameters driving the Earth’s terrestrial water and energy cycles, such as evapotranspiration (ET) rates and surface soil moisture (SSM), is of key significance. The water and energy cycles underpin global food and water security and need to be fully understood as the climate changes. In the last few decades, Earth Observation (EO) technology has played an increasingly important role in determining both ET and SSM. This paper reviews the state of the art in the use specifically of operational EO of both ET and SSM estimates. We discuss the key technical and operational considerations to derive accurate estimates of those parameters from space. The review suggests significant progress has been made in the recent years in retrieving ET and SSM operationally; yet, further work is required to optimize parameter accuracy and to improve the operational capability of services developed using EO data. Emerging applications on which ET/SSM operational products may be included in the context specifically in relation to agriculture are also highlighted; the operational use of those operational products in such applications remains to be seen

Contribution to advanced sensor development for passive imaging of the Earth

This work has been formally undertaken within the frame of the scholarship number BES-2012-053917 of 1 December 2012, by the "Secretario de Estado de Investigación del Ministerio de Economía y Competitividad" related to the program "Formación de Personal Investigador (FPI)". The scholarship is related to the research project at the Universitat Politècnica de Catalunya (UPC) number TEC2011-25865. In a more general scope, this thesis is related to the Remote Sensing Laboratory (Signal Theory & Communication Department, UPC) on-going activities, within the SMOS (Soil Moisture and Ocean Salinity) mission by the European Space Agency (ESA). These activities have been organized to provide original advances in the following four main topics: 1) SMOS calibration and performance. Since the launch of the instrument in 2009, SMOS imaging has been performing exclusively in co-polar mode. However, SMOS measurements are fully polarimetric. This feature was not operationally exploited due to the large errors yielded by full-pol images. In this context my work was addressed to support better characterization of the antenna. Based on the idea that SMOS polarization mode was recently implemented using Full-pol measurements, the so-called relative phases have been recomputed by using co-polar and cross-polar measurements. SMOS moderate Side Lobe Level (SLL) is caused by the limited coverage of the measured visibility samples in the frequency domain, so another objective of this work has been devoted to assess the impact of calibration errors into SMOS side lobes level (SLL). The main objective on this topic has been to reproduce by simulation SMOS measured side-lobe levels (SLL) by adding errors to a point source response, in order to identify the dominant source of error. During commissioning phase it was detected that SMOS heater system were introducing small and random sporadic PMS offset steps (jumps) in several units. Another work during this thesis has been devoted to mitigate those PMS jumps by trimming calibration date from single LICEF averaged TA jumps over the ocean. 2) SMOS spatial bias assessment. SMOS measurements still have mathematical image reconstruction errors that must be properly assessed. The aim of this work is to focus on the so-called "floor error", defined in an error free end-to-end image reconstruction simulation. In order to reduce this error, different inversion approaches have been implemented and tested, as the so-called Gibbs 2 approach 3) SMOS improved imaging. One of the problems of most concern within the SMOS mission is related to the so-called "land-sea contamination" (LSC), an artificial increase of ocean brightness temperature close to land masses. Therefore, a systematic assessment has been performed in this thesis in order to understand and mitigate this artifact. This subject is related to one of the main original outcomes of the thesis, since it has a relevant impact on the quality of SMOS imaging. The LSC mitigation technique developed during the work of the thesis has been presented and validated by different methods. 4) SMOS follow-on missions advanced configurations. This work is devoted to assess the impact of instrumental errors on the radiometric accuracy (pixel bias) of one of the selected array configurations of the so-called Super-MIRAS instrument. The aim of this work has been focused on the assessment of different array geometries and instrument architectures of future L-band synthetic aperture radiometers to improve spatial resolution while maintaining radiometric sensitivity.Esta tesis se ha llevado a cabo en el marco de la beca FPI BES-2012-053917 del 1 de diciembre de 2012, por el "Secretario de Estado de Investigación del Ministerio de Economía y Competitividad", asociada al proyecto TEC2011-25865 (Universidad Politècnica de Catalunya). En un sentido más amplio, el trabajo se engloba dentro de las actividades del Grupo de Teledetección (RSLab) del Departamento de Teoría de la Señal y Comunicaciones, UPC, en el marco de la misión SMOS (Soil Moisture and Ocean Salinity) de la Agencia Espacial Europea del Espacio (ESA). El trabajo se divide en: 1) Calibración y prestaciones del sensor SMOS Desde el lanzamiento del instrumento en 2009, la imagen de SMOS se ha obtenido utilizando medidas en modo co-polar. Sin embargo, las medidas en SMOS se realizan en full-pol. Esto no se había llevado a cabo debido a los grandes errores que se obtenían con imágenes en full-pol. En este contexto mi trabajo se ha enfocado en la realización de una mejor caracterización de la antena. Basado en la idea de que el modo full-pol ha sido recientemente implementado en SMOS, las fases relativas entre antenas han sido recalculadas utilizando medidas co-polares y cross-polares. Los lóbulos secundarios de SMOS (SLL) son causados por la cobertura limitada de las visibilidades medidas en el dominio frecuencial, así que otro de los objetivos de este trabajo ha sido analizar el impacto de errores de calibración en los lóbulos secundarios de SMOS. Básicamente se han reproducido los lóbulos secundarios de SMOS mediantes simulaciones añadiendo errores a una fuente puntual, identificando las principales fuentes de error. Durante la fase de comisionado se detectó que el sistema de calentamiento de SMOS introducía pequeños saltos aleatorios del offset del PMS en diferentes unidades. Para hacer un seguimiento y corregir estos saltos se realizaron calibraciones de offset semanales justo después de la fase de comisionado, así que otro de los trabajos realizados en esta tesis ha sido dirigido a mitigar estos saltos introduciendo calibraciones adicionales antes de los mismos a partir de medir la temperatura de antena media calculada en el océano. 2) Técnicas de reducción de los errores espaciales SMOS tiene un error matemático de reconstrucción en la imagen que ha sido investigado en este trabajo. Así que este trabajo se ha focalizado en el "floor error" definido como el error de reconstrucción en un instrumento ideal libre de errores. Para reducir este error se han utilizado diferentes aproximaciones como Gibbs 2. 3) Mejoras en la inversión de imagen Uno de los mayores problemas durante los primeros cinco años de misión SMOS ha sido la llamada "land-sea contamination" (contaminación tierra-mar). Así pues, se ha realizado un estudio sistemático para comprender y mitigar este artefacto. Este tema está relacionado con uno de los descubrimientos más importantes de esta tesis ya que este tiene un gran impacto en la calidad de la imagen de SMOS. La técnica encontrada para mitigar este error es presentada y validada mediante diferentes métodos. 4) Misiones futuras Este trabajo está enfocado en la investigación del impacto de errores instrumentales en la precisión radiométrica de errores espaciales de una de las posibles nuevas configuraciones de array propuestas para construir un nuevo instrumento llamado Super-MIRAS. El propósito principal de este trabajo está orientado en el desarrollo de diferentes geometrías de arrays y arquitecturas de instrumentos para una futura misión en banda L, en la que se diseñaría un nuevo radiómetro de apertura sintética para mejorar la resolución espacial manteniendo la sensibilidad radiométrica

Contribution to advanced sensor development for passive imaging of the Earth

This work has been formally undertaken within the frame of the scholarship number BES-2012-053917 of 1 December 2012, by the "Secretario de Estado de Investigación del Ministerio de Economía y Competitividad" related to the program "Formación de Personal Investigador (FPI)". The scholarship is related to the research project at the Universitat Politècnica de Catalunya (UPC) number TEC2011-25865. In a more general scope, this thesis is related to the Remote Sensing Laboratory (Signal Theory & Communication Department, UPC) on-going activities, within the SMOS (Soil Moisture and Ocean Salinity) mission by the European Space Agency (ESA). These activities have been organized to provide original advances in the following four main topics: 1) SMOS calibration and performance. Since the launch of the instrument in 2009, SMOS imaging has been performing exclusively in co-polar mode. However, SMOS measurements are fully polarimetric. This feature was not operationally exploited due to the large errors yielded by full-pol images. In this context my work was addressed to support better characterization of the antenna. Based on the idea that SMOS polarization mode was recently implemented using Full-pol measurements, the so-called relative phases have been recomputed by using co-polar and cross-polar measurements. SMOS moderate Side Lobe Level (SLL) is caused by the limited coverage of the measured visibility samples in the frequency domain, so another objective of this work has been devoted to assess the impact of calibration errors into SMOS side lobes level (SLL). The main objective on this topic has been to reproduce by simulation SMOS measured side-lobe levels (SLL) by adding errors to a point source response, in order to identify the dominant source of error. During commissioning phase it was detected that SMOS heater system were introducing small and random sporadic PMS offset steps (jumps) in several units. Another work during this thesis has been devoted to mitigate those PMS jumps by trimming calibration date from single LICEF averaged TA jumps over the ocean. 2) SMOS spatial bias assessment. SMOS measurements still have mathematical image reconstruction errors that must be properly assessed. The aim of this work is to focus on the so-called "floor error", defined in an error free end-to-end image reconstruction simulation. In order to reduce this error, different inversion approaches have been implemented and tested, as the so-called Gibbs 2 approach 3) SMOS improved imaging. One of the problems of most concern within the SMOS mission is related to the so-called "land-sea contamination" (LSC), an artificial increase of ocean brightness temperature close to land masses. Therefore, a systematic assessment has been performed in this thesis in order to understand and mitigate this artifact. This subject is related to one of the main original outcomes of the thesis, since it has a relevant impact on the quality of SMOS imaging. The LSC mitigation technique developed during the work of the thesis has been presented and validated by different methods. 4) SMOS follow-on missions advanced configurations. This work is devoted to assess the impact of instrumental errors on the radiometric accuracy (pixel bias) of one of the selected array configurations of the so-called Super-MIRAS instrument. The aim of this work has been focused on the assessment of different array geometries and instrument architectures of future L-band synthetic aperture radiometers to improve spatial resolution while maintaining radiometric sensitivity.Esta tesis se ha llevado a cabo en el marco de la beca FPI BES-2012-053917 del 1 de diciembre de 2012, por el "Secretario de Estado de Investigación del Ministerio de Economía y Competitividad", asociada al proyecto TEC2011-25865 (Universidad Politècnica de Catalunya). En un sentido más amplio, el trabajo se engloba dentro de las actividades del Grupo de Teledetección (RSLab) del Departamento de Teoría de la Señal y Comunicaciones, UPC, en el marco de la misión SMOS (Soil Moisture and Ocean Salinity) de la Agencia Espacial Europea del Espacio (ESA). El trabajo se divide en: 1) Calibración y prestaciones del sensor SMOS Desde el lanzamiento del instrumento en 2009, la imagen de SMOS se ha obtenido utilizando medidas en modo co-polar. Sin embargo, las medidas en SMOS se realizan en full-pol. Esto no se había llevado a cabo debido a los grandes errores que se obtenían con imágenes en full-pol. En este contexto mi trabajo se ha enfocado en la realización de una mejor caracterización de la antena. Basado en la idea de que el modo full-pol ha sido recientemente implementado en SMOS, las fases relativas entre antenas han sido recalculadas utilizando medidas co-polares y cross-polares. Los lóbulos secundarios de SMOS (SLL) son causados por la cobertura limitada de las visibilidades medidas en el dominio frecuencial, así que otro de los objetivos de este trabajo ha sido analizar el impacto de errores de calibración en los lóbulos secundarios de SMOS. Básicamente se han reproducido los lóbulos secundarios de SMOS mediantes simulaciones añadiendo errores a una fuente puntual, identificando las principales fuentes de error. Durante la fase de comisionado se detectó que el sistema de calentamiento de SMOS introducía pequeños saltos aleatorios del offset del PMS en diferentes unidades. Para hacer un seguimiento y corregir estos saltos se realizaron calibraciones de offset semanales justo después de la fase de comisionado, así que otro de los trabajos realizados en esta tesis ha sido dirigido a mitigar estos saltos introduciendo calibraciones adicionales antes de los mismos a partir de medir la temperatura de antena media calculada en el océano. 2) Técnicas de reducción de los errores espaciales SMOS tiene un error matemático de reconstrucción en la imagen que ha sido investigado en este trabajo. Así que este trabajo se ha focalizado en el "floor error" definido como el error de reconstrucción en un instrumento ideal libre de errores. Para reducir este error se han utilizado diferentes aproximaciones como Gibbs 2. 3) Mejoras en la inversión de imagen Uno de los mayores problemas durante los primeros cinco años de misión SMOS ha sido la llamada "land-sea contamination" (contaminación tierra-mar). Así pues, se ha realizado un estudio sistemático para comprender y mitigar este artefacto. Este tema está relacionado con uno de los descubrimientos más importantes de esta tesis ya que este tiene un gran impacto en la calidad de la imagen de SMOS. La técnica encontrada para mitigar este error es presentada y validada mediante diferentes métodos. 4) Misiones futuras Este trabajo está enfocado en la investigación del impacto de errores instrumentales en la precisión radiométrica de errores espaciales de una de las posibles nuevas configuraciones de array propuestas para construir un nuevo instrumento llamado Super-MIRAS. El propósito principal de este trabajo está orientado en el desarrollo de diferentes geometrías de arrays y arquitecturas de instrumentos para una futura misión en banda L, en la que se diseñaría un nuevo radiómetro de apertura sintética para mejorar la resolución espacial manteniendo la sensibilidad radiométrica.Postprint (published version

Comparison of measured brightness temperatures from SMOS with modelled ones from ORCHIDEE and H-TESSEL over the Iberian Peninsula

L-band radiometry is considered to be one of the most suitable techniques to estimate surface soil moisture (SSM) by means of remote sensing. Brightness temperatures are key in this process, as they are the main input in the retrieval algorithm which yields SSM estimates. The work exposed compares brightness temperatures measured by the SMOS mission to two different sets of modelled ones, over the Iberian Peninsula from 2010 to 2012. The two modelled sets were estimated using a radiative transfer model and state variables from two land-surface models: (i) ORCHIDEE and (ii) H-TESSEL. The radiative transfer model used is the CMEM. Measured and modelled brightness temperatures show a good agreement in their temporal evolution, but their spatial structures are not consistent. An empirical orthogonal function analysis of the brightness temperature's error identifies a dominant structure over the south-west of the Iberian Peninsula which evolves during the year and is maximum in autumn and winter. Hypotheses concerning forcing-induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for the weak spatial correlations at the moment. Further hypotheses are proposed and will be explored in a forthcoming paper. The analysis of spatial inconsistencies between modelled and measured TBs is important, as these can affect the estimation of geophysical variables and TB assimilation in operational models, as well as result in misleading validation studies

Synergistic optical and microwave remote sensing approaches for soil moisture mapping at high resolution

Aplicat embargament des de la data de defensa fins al dia 1 d'octubre de 2022Soil moisture is an essential climate variable that plays a crucial role linking the Earth’s water, energy, and carbon cycles. It is responsible for the water exchange between the Earth’s surface and the atmosphere, and provides key information about soil evaporation, plant transpiration, and the allocation of precipitation into runoff, surface flow and infiltration. Therefore, an accurate estimation of soil moisture is needed to enhance our current climate and meteorological forecasting skills, and to improve our current understanding of the hydrological cycle and its extremes (e.g., droughts and floods). L-band Microwave passive and active sensors have been used during the last decades to estimate soil moisture, since there is a strong relationship between this variable and the soil dielectric properties. Currently, there are two operational L-band missions specifically devoted to globally measure soil moisture: the ESA’s Soil Moisture and the Ocean Salinity (SMOS), launched in November 2009; and the NASA’s Soil Moisture Active Passive (SMAP), launched in January 2015. The spatial resolution of the SMOS and SMAP radiometers, in the order of tens of kilometers (~40 km), is adequate for global applications. However, to fulfill the needs of a growing number of applications at local or regional scale, higher spatial detail (< 1 km) is required. To bridge this gap and improve the spatial resolution of the soil moisture maps, a variety of spatial enhancement or spatial (sub-pixel) disaggregation approaches have been proposed. This Ph.D. Thesis focuses on the study of the Earth’s surface soil moisture from remotely sensed observations. This work includes the implementation of several soil moisture retrieval techniques and the development, implementation, validation and comparison of different spatial enhancement or downscaling techniques, applied at local, regional, and continental scale. To meet these objectives, synergies between several active/passive microwave sensors (SMOS, SMAP and Sentinel-1) and optical/thermal sensors (MODIS) have been explored. The results are presented as follows: - Spatially consistent downscaling approach for SMOS using an adaptive moving window A passive microwave/optical downscaling algorithm for SMOS is proposed to obtain fine-scale soil moisture maps (1 km) from the native resolution (~40 km) of the instrument. This algorithm introduces the concept of a shape-adaptive window as a central improvement of the disaggregation technique presented by Piles et al. (2014), allowing its application at continental scales. - Assessment of multi-scale SMOS and SMAP soil moisture products across the Iberian Peninsula The temporal and spatial characteristics of SMOS and SMAP soil moisture products at coarse- and fine-scales are assessed in order to learn about their distinct features and the rationale behind them, tracing back to the physical assumptions they are based upon. - Impact of incidence angle diversity on soil moisture retrievals at coarse and fine scales An incidence angle (32.5°, 42.5° and 52.5°)-adaptive calibration of radiative transfer effective parameters single scattering albedo and soil roughness has been carried out, highlighting the importance of such parameterization to accurately estimate soil moisture at coarse-resolution. Then, these parameterizations are used to examine the potential application of a physically-based active-passive downscaling approach to upcoming microwave missions, namely CIMR, ROSE-L and Sentinel-1 Next Generation. Soil moisture maps obtained for the Iberian Peninsula at the three different angles, and at coarse and fine scales are inter-compared using in situ measurements and model data as benchmarks.La humedad del suelo es una variable climática esencial que juega un papel crucial en la relación de los ciclos del agua, la energía y el carbono de la Tierra. Es responsable del intercambio de agua entre la superficie de la Tierra y la atmósfera, y proporciona información crucial sobre la evaporación del suelo, la transpiración de las plantas y la distribución de la precipitación en escorrentía, flujo superficial e infiltración. Por lo tanto, es necesaria una estimación precisa de la humedad del suelo para mejorar las predicciones climáticas y meteorológicas, y comprender mejor el ciclo hidrológico y sus extremos (v.g., sequías e inundaciones). Los sensores pasivos y activos en banda L se han usado durante las últimas décadas para estimar la humedad del suelo debido a la relación directa que existe entre esta variable y las propiedades dieléctricas del suelo. Actualmente, hay dos misiones operativas en banda L específicamente dedicadas a medir la humedad del suelo a escala global: la misión Soil Moisture and Ocean Salinity (SMOS) de la ESA, lanzada en noviembre de 2009; y la misión Soil Moisture Active Passive (SMAP) de la NASA, lanzada en enero de 2015. La resolución espacial de los radiómetros SMOS y SMAP, del orden de unas decenas de kilómetros (~40 km), es adecuada para aplicaciones a escala global. Sin embargo, para satisfacer las necesidades de un número creciente de aplicaciones a escala local o regional, se requiere más detalle espacial (<1 km). Para solventar esta limitación y mejorar la resolución espacial de los mapas de humedad, se han propuesto diferentes técnicas de mejora o desagregación espacial. Esta Tesis se centra en el estudio de la humedad de la superficie terrestre a partir de datos obtenidos a través de teledetección. Este trabajo incluye la implementación de distintos algoritmos de recuperación de la humedad del suelo y el desarrollo, implementación, validación y comparación de distintas técnicas de desagregación, aplicadas a escala local, regional y continental. Para cumplir estos objetivos, se han explorado sinergias entre diferentes sensores de microondas activos/pasivos (SMOS, SMAP y Sentinel-1) y sensores ópticos/térmicos. Los resultados se presentan de la siguiente manera: - Técnica de desagregación espacialmente consistente, basada en una ventana móvil adaptativa, aplicada a los datos SMOS Se propone un algoritmo de desagregación del píxel basado en datos obtenidos de medidas radiométricas de microondas en banda L y datos ópticos, para mejorar la resolución espacial de los mapas de humedad del suelo desde la resolución nativa del instrumento (~40 km) hasta resoluciones de 1 km. El algoritmo introduce el concepto de una ventana de contorno adaptativo, como mejora principal sobre la técnica de desagregación presentada en Piles et al. (2014), permitiendo su implementación a escala continental. - Análisis multiescalar de productos de humedad del suelo SMAP y SMOS sobre la Península Ibérica Se han evaluado las características temporales y espaciales de distintos productos de humedad del suelo SMOS y SMAP, a baja y a alta resolución, para conocer sus características distintivas y comprender las razones de sus diferencias. Para ello, ha sido necesario rastrear los supuestos físicos en los que se basan. - Impacto del ángulo de incidencia en la recuperación de la humedad del suelo a baja y a alta resolución Se ha llevado a cabo una calibración adaptada al ángulo de incidencia (32.5°, 42.5° y 52.5°) de los parámetros efectivos, albedo de dispersión simple y rugosidad del suelo, descritos en el modelo de transferencia radiativa � − �, incidiendo en la importancia de esta parametrización para estimar la humedad del suelo de forma precisa a baja resolución. El resultado de las mismas se ha utilizado para estudiar la potencial aplicación de un algoritmo activo/pasivo de desagregación basado en la física para las próximas misiones de microondas, llamadas CIMR, ROSE-L y Sentinel-1 Next Generation. Los mapas de humedad recuperados a los tres ángulos de incidencia, tanto a baja como a alta resolución, se han obtenido para la Península Ibérica y se han comparado entre ellos usando como referencia mediciones de humedad in situ.Postprint (published version