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Maria-José Escorihuela

Bio: Maria-José Escorihuela is an academic researcher. The author has contributed to research in topics: Radiometer & Water level. The author has an hindex of 3, co-authored 10 publications receiving 1375 citations.

Papers
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Journal ArticleDOI
12 Apr 2010
TL;DR: The SMOS satellite was launched successfully on November 2, 2009, and will achieve an unprecedented maximum spatial resolution of 50 km at L-band over land (43 km on average over the field of view), providing multiangular dual polarized (or fully polarized) brightness temperatures over the globe.
Abstract: It is now well understood that data on soil moisture and sea surface salinity (SSS) are required to improve meteorological and climate predictions. These two quantities are not yet available globally or with adequate temporal or spatial sampling. It is recognized that a spaceborne L-band radiometer with a suitable antenna is the most promising way of fulfilling this gap. With these scientific objectives and technical solution at the heart of a proposed mission concept the European Space Agency (ESA) selected the Soil Moisture and Ocean Salinity (SMOS) mission as its second Earth Explorer Opportunity Mission. The development of the SMOS mission was led by ESA in collaboration with the Centre National d'Etudes Spatiales (CNES) in France and the Centro para el Desarrollo Tecnologico Industrial (CDTI) in Spain. SMOS carries a single payload, an L-Band 2-D interferometric radiometer operating in the 1400-1427-MHz protected band . The instrument receives the radiation emitted from Earth's surface, which can then be related to the moisture content in the first few centimeters of soil over land, and to salinity in the surface waters of the oceans. SMOS will achieve an unprecedented maximum spatial resolution of 50 km at L-band over land (43 km on average over the field of view), providing multiangular dual polarized (or fully polarized) brightness temperatures over the globe. SMOS has a revisit time of less than 3 days so as to retrieve soil moisture and ocean salinity data, meeting the mission's science objectives. The caveat in relation to its sampling requirements is that SMOS will have a somewhat reduced sensitivity when compared to conventional radiometers. The SMOS satellite was launched successfully on November 2, 2009.

1,553 citations

Journal ArticleDOI
TL;DR: In this article, the interferometric mode of CryoSat-2 was used to map broad (5 km wide) swaths of surface elevation with fine (500 m) spatial resolution from each satellite pass, providing a step-change in the capability of satellite altimetry for glaciology.

65 citations

29 Mar 2006
TL;DR: In this article, the effects of the litter and heterogeneities of the ground are probably important but still are very ignored, and an experimental approach in laboratory and in situ is developed to take measurements for various configurations (frequency, temporal, polarization, incidence, Bi-statics, Brewster effect...) and in terms of surface conditions (homogeneous or heterogeneous ground, more or less wet, presence of litter).
Abstract: The work which we present takes place within the framework of mission SMOS of the ESA which will consist to send a radiometer (1.4 GHz) in space. The goal of the research which we propose is the improvement of the comprehension of the effects of structure soil and litter. The effects of the litter and heterogeneities of the ground are probably important but still are very ignored. So we developed an experimental approach in laboratory and in situ. That makes it possible to take measurements for various configurations (frequency, temporal, polarization, incidence, Bi-statics, Brewster effect...) and in term of surface conditions(homogeneous or heterogeneous ground, more or less wet, presence of litter...). Measurements at the laboratory with waveguide enabled us to characterize the various components of the geological structure (ground, rocks) and to check the model of Dobson usually used.

5 citations

01 May 2005
TL;DR: In this paper, a numerical model is developed to simulate complex geological structures to calculate the equivalent permittivity of these geological structures in order to be able to associate with each radiometer measurement an equivalent moisture.
Abstract: The surface soil moisture is a key variable to describe the exchange of water and energy between the land and the atmosphere. In hydrology, and meteorology, the amount of water in the upper soil layers permits (0-5 cm from the surface) the evaluation of the relationship between the real evaporation and the potential evaporation of the bare soil. It is also possible to determine the distribution of rainfall or other variables such as hydraulic conductivity. Studies have shown that microwave sensors could be used to scan the surface soil moisture. The solution choose by the team associated with the SMOS mission (Soil Moisture and Ocean Salinity) is to use a radiometer (1.4 GHz) to identify soil microwave emissions . The measurements are made on the site of CESBIO in Toulouse where a 1.4 GHz radiometer is installed . The effect of vegetation cover, soil temperatures, snow cover, topography or moisture variations have an important role in the broadcast microwave surface. Other parameters such as the presence of inclusions in the ground (holes, stones), or soil texture can also disrupt measurements. The aim of the work that we present in this paper is to develop a numerical model to simulate complex geological structures. This model must take into account all parameters that can affect the equivalent permittivity measured by the radiometer (surface, moisture variation ,... inclusions). The purpose of this model is to calculate the equivalent permittivity of these geological structures in order to be able to associate with each radiometer measurement an equivalent moisture.

2 citations

Proceedings ArticleDOI
01 Jul 2018
TL;DR: Three specialized algorithms or retrackers to retrieve water levels from radar altimeter data over inland water bodies dedicated to restricting the land contamination of the signal are presented.
Abstract: The water level of inland water bodies plays an essential role in water balance management. Satellite altimeters can play an important role in monitoring water level, namely in remotely access places. However, satellite altimeters are normally designed to monitor homogeneous surfaces such as oceans or ice sheets, which results in poor performance over small inland water bodies because of the land contamination contribution in the returned waveforms. This paper presents three specialized algorithms or retrackers to retrieve water levels from radar altimeter data over inland water bodies dedicated to restricting the land contamination of the signal. The performances of the waveform portion selection method and the three retrackers which are the threshold retracker, Offset Center of Gravity (OCOG) retracker and 2-step analytical retracker are compared. Time series of water level results are retrieved over water bodies in Ebre river basin (Catalunya, Spain) and Lake Volta (West Africa). The standard deviation for 2-step analytical retracker combined with the waveform portion selection ranges from 0.02m to 0.05m, for OCOG retracker ranges from 0.07m to 0.13m, and for threshold re-tracker, it ranges from 0.05m to 0.1m over Lake Volta. The results show good accuracy with the insitu measurements over lake Ebre and Ribarroja reservoir with RMSE about 0.44 m and 0.18 m separately. All performances of the three retrackers are compared with the onboard retracker as well.

1 citations


Cited by
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Journal ArticleDOI
06 May 2010
TL;DR: The Soil Moisture Active Passive mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council's Decadal Survey to make global measurements of the soil moisture present at the Earth's land surface.
Abstract: The Soil Moisture Active Passive (SMAP) mission is one of the first Earth observation satellites being developed by NASA in response to the National Research Council's Decadal Survey SMAP will make global measurements of the soil moisture present at the Earth's land surface and will distinguish frozen from thawed land surfaces Direct observations of soil moisture and freeze/thaw state from space will allow significantly improved estimates of water, energy, and carbon transfers between the land and the atmosphere The accuracy of numerical models of the atmosphere used in weather prediction and climate projections are critically dependent on the correct characterization of these transfers Soil moisture measurements are also directly applicable to flood assessment and drought monitoring SMAP observations can help monitor these natural hazards, resulting in potentially great economic and social benefits SMAP observations of soil moisture and freeze/thaw timing will also reduce a major uncertainty in quantifying the global carbon balance by helping to resolve an apparent missing carbon sink on land over the boreal latitudes The SMAP mission concept will utilize L-band radar and radiometer instruments sharing a rotating 6-m mesh reflector antenna to provide high-resolution and high-accuracy global maps of soil moisture and freeze/thaw state every two to three days In addition, the SMAP project will use these observations with advanced modeling and data assimilation to provide deeper root-zone soil moisture and net ecosystem exchange of carbon SMAP is scheduled for launch in the 2014-2015 time frame

2,474 citations

Journal ArticleDOI
TL;DR: A retrieval algorithm to deliver global soil moisture (SM) maps with a desired accuracy of 0.04 m3/m3 is given, discusses the caveats, and provides a glimpse of the Cal Val exercises.
Abstract: The Soil Moisture and Ocean Salinity (SMOS) mission is European Space Agency (ESA's) second Earth Explorer Opportunity mission, launched in November 2009. It is a joint program between ESA Centre National d'Etudes Spatiales (CNES) and Centro para el Desarrollo Tecnologico Industrial. SMOS carries a single payload, an L-Band 2-D interferometric radiometer in the 1400-1427 MHz protected band. This wavelength penetrates well through the atmosphere, and hence the instrument probes the earth surface emissivity. Surface emissivity can then be related to the moisture content in the first few centimeters of soil, and, after some surface roughness and temperature corrections, to the sea surface salinity over ocean. The goal of the level 2 algorithm is thus to deliver global soil moisture (SM) maps with a desired accuracy of 0.04 m3/m3. To reach this goal, a retrieval algorithm was developed and implemented in the ground segment which processes level 1 to level 2 data. Level 1 consists mainly of angular brightness temperatures (TB), while level 2 consists of geophysical products in swath mode, i.e., as acquired by the sensor during a half orbit from pole to pole. In this context, a group of institutes prepared the SMOS algorithm theoretical basis documents to be used to produce the operational algorithm. The principle of the SM retrieval algorithm is based on an iterative approach which aims at minimizing a cost function. The main component of the cost function is given by the sum of the squared weighted differences between measured and modeled TB data, for a variety of incidence angles. The algorithm finds the best set of the parameters, e.g., SM and vegetation characteristics, which drive the direct TB model and minimizes the cost function. The end user Level 2 SM product contains SM, vegetation opacity, and estimated dielectric constant of any surface, TB computed at 42.5°, flags and quality indices, and other parameters of interest. This paper gives an overview of the algorithm, discusses the caveats, and provides a glimpse of the Cal Val exercises.

846 citations

Journal ArticleDOI
TL;DR: In this paper, the authors describe the magnitude of the soil moisture upscaling problem and measurement density requirements for ground-based soil moisture networks, and summarize a number of existing soil moisture-upscaling strategies which may reduce the detrimental impact of spatial sampling errors on the reliability of satellite soil moisture validation using spatially sparse ground based observations.
Abstract: [1] The contrast between the point-scale nature of current ground-based soil moisture instrumentation and the ground resolution (typically >102 km2) of satellites used to retrieve soil moisture poses a significant challenge for the validation of data products from current and upcoming soil moisture satellite missions. Given typical levels of observed spatial variability in soil moisture fields, this mismatch confounds mission validation goals by introducing significant sampling uncertainty in footprint-scale soil moisture estimates obtained from sparse ground-based observations. During validation activities based on comparisons between ground observations and satellite retrievals, this sampling error can be misattributed to retrieval uncertainty and spuriously degrade the perceived accuracy of satellite soil moisture products. This review paper describes the magnitude of the soil moisture upscaling problem and measurement density requirements for ground-based soil moisture networks. Since many large-scale networks do not meet these requirements, it also summarizes a number of existing soil moisture upscaling strategies which may reduce the detrimental impact of spatial sampling errors on the reliability of satellite soil moisture validation using spatially sparse ground-based observations.

601 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide an overview and synthesis of some of the most notable types of land cover changes and their impacts on climate, including agriculture, deforestation and afforestation, desertification, and urbanization.
Abstract: Land cover changes (LCCs) play an important role in the climate system. Research over recent decades highlights the impacts of these changes on atmospheric temperature, humidity, cloud cover, circulation, and precipitation. These impacts range from the local- and regional-scale to sub-continental and global-scale. It has been found that the impacts of regional-scale LCC in one area may also be manifested in other parts of the world as a climatic teleconnection. In light of these findings, this article provides an overview and synthesis of some of the most notable types of LCC and their impacts on climate. These LCC types include agriculture, deforestation and afforestation, desertification, and urbanization. In addition, this article provides a discussion on challenges to, and future research directions in, assessing the climatic impacts of LCC.

560 citations