Surface topography and mixed-pixel effects on the simulated L-band brightness temperatures.


Autoria(s): Talone, Marco; Camps Carmona, Adriano José; Monerris Belda, Alessandra; Vall-Llossera Ferran, Mercedes Magdalena; Ferrazzoli, P.; Piles, Maria
Contribuinte(s)

Universitat Politècnica de Catalunya. Departament de Teoria del Senyal i Comunicacions

Data(s)

10/05/2012

Resumo

The impact of topography and mixed pixels on L-band radiometric observations over land needs to be quantified to improve the accuracy of soil moisture retrievals. For this purpose, a series of simulations has been performed with an improved version of the soil moisture and ocean salinity (SMOS) end-to-end performance simulator (SEPS). The brightness temperature generator of SEPS has been modified to include a 100-m-resolution land cover map and a 30-m-resolution digital elevation map of Catalonia (northeast of Spain). This high-resolution generator allows the assessment of the errors in soil moisture retrieval algorithms due to limited spatial resolution and provides a basis for the development of pixel disaggregation techniques. Variation of the local incidence angle, shadowing, and atmospheric effects (up- and downwelling radiation) due to surface topography has been analyzed. Results are compared to brightness temperatures that are computed under the assumption of an ellipsoidal Earth.

The impact of topography and mixed pixels onL-band radiometric observations over land needs to be quantified to improve the accuracy of soil moisture retrievals. Forthis purpose, a series of simulations has been performed with an improved version of the Soil Moisture and Ocean Salinity (SMOS) End-to-End Performance Simulator (SEPS). The brightness temperature (TB) generator of SEPS has been modified to include a 100-m-resolution land cover map and a 30-m-resolution digital elevation map of Catalonia (northeast of Spain). This highresolution TB generator allows the assessment of the errors in soil moisture retrieval algorithms due to limited spatial resolution and provides a basis for the development of pixel disaggregation techniques. Variation of the local incidence angle, shadowing, and atmospheric effects (up- and downwelling radiation) due tosurface topography has been analyzed. THE AVAILABILITY of high-resolution brightness temperature (TB) maps at L-band is crucial to analyze important issues dealing with bare and vegetation-covered land emission and to develop inversion algorithms in preparation for real Soil Moisture and Ocean Salinity (SMOS) mission data.Mixed-pixel, coastlines, shadowing, and topography effects on the measured brightness temperatures need further study, but the lack of global geophysical data at sufficient temporal and spatial resolution and the large amount of data involved inthe generation of high-resolution TB maps on a global basis complicate the issue. In fact, in spite of the existence of globaldigital elevation models with sufficient spatial resolution, accurate land cover data do not exist for most parts of the world.To address these issues, a series of simulations has been performed with an improved version of the SMOS End-to-EndPerformance Simulator (SEPS) [1], [2], in which, to date, all points on Earth have been assumed to be at sea level. The study has been done over the region of Catalonia, on the northeastern coast of Spain, because of its many different land cover types,topography, and the presence of a coastline. A 30-m-resolution digital elevation map [3] and a 100-m-resolution land coverage map of Catalonia [4] have been used as inputs, and SEPS has been conveniently modified to generate high-resolution TB maps of this area. A variety of soil and land cover types (crops, bushes, marshes, etc.) have been parameterized using the values obtained from field experiments and literature [5]–[10], [12].

Identificador

http://hdl.handle.net/2117/9111

Idioma(s)

eng

Publicador

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Direitos

Consulteu les condicions d'ús d'aquest document en el repositori original:<a href="http://hdl.handle.net/2117/9111">http://hdl.handle.net/2117/9111</a>

Palavras-Chave #Àrees temàtiques de la UPC::Enginyeria electrònica i telecomunicacions::Radiocomunicació i exploració electromagnètica::Teledetecció #Brightness temperature #Image processing #Moisture #Topography #Vegetation mapping #Radiometry #Soil moisture #L-band radiometry #mixed pixel #simulator #SMOS End-to-End Performance Simulator (SEPS) #Soil Moisture #topography #Imatges -- Processament #Hidratació #Topografia #Radiometria #Humitat del sòl
Tipo

info:eu-repo/semantics/article