Utilize este identificador para referenciar este registo: http://hdl.handle.net/10451/35040
Título: The use of remotely sensed land surface temperature for climate monitoring
Autor: Bento, Virgílio
Orientador: Camara, Carlos Portugal da, 1957-
Trigo, Isabel Franco, 1969-
Palavras-chave: Teses de doutoramento - 2018
Data de Defesa: 2018
Resumo: Satellite remote sensing of the Earth has been continuously performed from different satellite platforms/constellations since the 1960s. The amount of radiometric information available in organisations like the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) may be compiled in Fundamental Climate Data Records (FCDRs), allowing the retrieval of climate records of geophysical variables, such as Land Surface Temperature (LST). Climate Data Records (CDRs) may then be used in a wide range of applications – such as drought monitoring or climate change studies, among others. Nevertheless, instruments onboard satellites of the same series, spanning decades of observations, may have different characteristics, which imposes a difficulty in the retrieval of LST. One of the most notable examples is the electromagnetic channels at which the earth is observed by these instruments. EUMETSAT Meteosat First Generation (MFG) – first launched in 1977 and last launched in 1997 – was designed to carry an instrument with only one channel in the thermal infrared region of the electromagnetic spectrum. On the other hand, Meteosat Second Generation (MSG) satellites – first launched in 2004 and currently still in operation – were designed to cover two thermal infrared channels. Since retrievals of LST are based on information from that window of the electromagnetic spectrum, and retrieval algorithms are usually based on a split-windows (two adjacent thermal infrared windows) methodology – typically the Generalised Split Windows (GSW) – a different approach must be taken to homogenise the retrievals over a long period of time, with the aim of compiling an LST CDR. In this context, this thesis aims at developing single-channel/mono-window algorithms that can be used with information from MFG and MSG constellations of satellites. Two algorithms were developed – the Statistical Mono-Window (SMW) and the Physical Mono-Window (PMW) – and consequently two climate data records were compiled in partnership with the Satellite Application Facility on Climate Monitoring (CM SAF) and Land Surface Analysis (LSA SAF). These CDRs are now available to download at the CM SAF website. The mentioned retrieval algorithms are sensitive to the amount of water vapor present on the atmosphere and use information from ECMWF ERA-Interim fields. However, its relatively coarse spatial resolution may lead to systematic errors in the humidity profiles with implications in LST, particularly over mountainous areas. This limitation was studied, and its implications discussed in this thesis with focus on the improvement of the LST retrievals over these high-altitude regions. Also, a discussion is provided focusing on the best process for the calibration of regression coefficients that constitute SMW and GSW. Another objective of this thesis is to use an LST CDR for an application focused on drought monitoring. The Vegetation Health Index (VHI) has been widely used for monitoring and characterising droughts. This index takes into account ecosystem features in terms of fluctuations between prescribed maxima and minima of NDVI (Vegetation Condition Index, VCI) and of Land Surface Temperature (LST; Thermal Condition Index, TCI), and is estimated as the weighted sum of these two contributions. Since there is no a priori knowledge about vegetation and temperature contributions, VHI is typically taken as the average of both contributions, i.e., a weight of 0.5 is assumed. It is shown that by maximising the correlations between VHI and the multiscalar drought indicator SPEI (Standardized Precipitation-Evapotranspiration Index) it is possible to evaluate the relative roles of VCI and TCI for different climate regions. This application is developed over a Euro-Mediterranean region and then further applied on a global scale and over the Meteosat disk, using the LST CDR previously developed. In summary, this thesis is focused on the development, improvement and application of LST climate data records.
Descrição: Tese de doutoramento, Ciências Geofísicas e da Geoinformação (Deteção Remota), Universidade de Lisboa, Faculdade de Ciências, 2018
URI: http://hdl.handle.net/10451/35040
Designação: Doutoramento em Ciências Geofísicas e da Geoinformação
Aparece nas colecções:FC - Teses de Doutoramento

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