Land surface temperature retrieval from MSG1-SEVIRI data
Introduction
The Meteosat Second Generation 1 (MSG1) satellite, renamed Meteosat-8, was launched on August 2002 and is becoming fully operational in early 2004. The objective of the mission is to improve weather forecasting and get a better understanding of the planet’s climate and its potential changes. MSG1 is a meteorological geostationary satellite developed by the European Space Agency (ESA) in close cooperation with the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), situated at 36000 km altitude and centered at 0° latitude above the Equator. Fig. 1 shows the MSG1 field of view compared with other geostationary satellites. Two sensors are placed on this satellite; the Geostationary Earth Radiation Budget (GERB), and the Spinning Enhanced Visible and Infrared Imager (SEVIRI). The GERB is a scanning radiometer with two broadband channels, one covering the solar spectrum, the other covering the entire electromagnetic spectrum. The objective of this sensor is to retrieve radiative fluxes of reflected solar radiation and emitted thermal radiation. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) is the main payload on board MSG1. This optical imaging radiometer consists of three visible and near infrared channels centered at 0.6, 0.8 and 1.6 μm, eight infrared channels centered at 3.9, 6.2, 7.3, 8.7, 9.7, 10.8, 12.0 and 13.4 μm and finally one visible broadband channel at 0.5–0.9 μm called the High Resolution Visible channel (HRV). In the following, SEVIRI channels will labeled according to their specifications given in the EUMETSAT technical information, namely, VIS0.6, VIS0.8, IR 1.6, IR 3.9, WV6.2, WV7.3, IR 8.7, IR 9.7, IR 10.8, IR 12.0, IR 13.4, and HRV.
The MSG1 improves the first generation of Meteosat satellites in terms of spatial resolution, frequency of image acquisition, and number of observation bands. The spatial resolution for HRV is 1 km and for the other infrared and visible channels is 3 km. This compares with 5 km for previous Meteosat satellites. There is one image acquisition every 15 min, compared with 30 min per acquisition for previous Meteosat satellites. The new Meteosat satellite has four visible channels that study the sunlight reflected from the Earth's surface and clouds, in comparison with the previous Meteosat camera that has only one visible channel. Eight infrared channels enhance the two thermal infrared bands on the first Meteosat. Four of them are absorption bands of total atmospheric water vapour (W), CO2 and O3, and the remaining four allow the land surface, sea surface, and clouds temperature to be determined (Schmid, 2000).
Having all these advantages in mind, the aim of this paper is to provide a simplified algorithm to obtain the land surface temperature (LST) from SEVIRI sensor data. To this end, Section 2 describes the theory associated with the LST retrieval and presents the simulations made using MODTRAN 3.5. The results are explained in Section 3 where the numerical values of the coefficients for the proposed two-channel algorithm are given. Finally we include a sensitivity analysis and, by considering a simulated dataset different from that one used to obtain the algorithm, we test the algorithm.
Section snippets
Two-channel algorithm
The radiative transfer equation applied to the infrared region of the electromagnetic spectrum gives, for a cloud free atmosphere under local thermodynamic equilibrium, the radiance measured from the sensor in channel i under a zenith observation angle θ according to:
Three contributions are taken into account: (a) the surface emission that is attenuated by the atmosphere, (b) the upwelling atmosphere emission towards the sensor, and (c) the downwelling
Two-channel algorithm coefficients
In this section the numerical values of the coefficients given by Eq. (3) after each simulation are presented, as are the brightness temperature calculations. In order to determine these values the Levenberg-Marquardt regression method was used, which is a modification of Gauss-Newton algorithm for non-linear minimizations. The standard deviations of the minimizations for all the possible SEVIRI thermal infrared channel combinations and angles are shown in Table 1. The outputs in this table
Conclusions
In this paper a general and operational algorithm to retrieve LST from MSG1-SEVIRI sensor data is presented. IR 10.8 and IR 12.0 channels are used to develop a split-window algorithm as a function of the satellite zenith observation angle. This work is original in that it addresses the question of the necessity of new algorithms for these new generation data. From simulations it is shown that the LST can be obtained from SEVIRI data with accuracy lower than 1.5 K for the most of the situations
Acknowledgements
The authors wish to thank Dr. Gail Andersson from the Air Force Research Laboratory, Hanscom (USA) for providing us with the MODTRAN 3.5 program, Maisoon Al-Jawad for the grammar supervision and The European Union (EAGLE, project SST3-CT-2003-502057) and the “Ministerio de Ciencia y Tecnologı́a” (project REN2001-3105/CLI) for financial support. This work has been carried out while Mireia Romaguera was in receipt of a grant from the “Agència Valenciana de Ciència i Tecnologia”.
References (16)
- et al.
Emissivity of terrestrial materials in the 8–14 μm atmospheric window
Remote Sensing of Environment
(1992) - Abreu, L. W., & Anderson, G. P., (Eds.). (1996). The MODTRAN 2/3 Report and LOWTRAN 7 MODEL, Modtran Report, Contract...
- et al.
Meteosat Second Generation. A comparison of on-ground and on-flight Imaging and Radiometric performances of SEVIRI on MSG-1
- et al.
Potential of MSG for surface temperature and emissivity estimation: considerations for real-time applications
International Journal of Remote Sensing
(2002) - et al.
Daily net radiation estimated from air temperature and NOAAAVHRR data: a case study for the Iberian Peninsula
International Journal of Remote Sensing
(2001) - et al.
A new approach for retrieving precipitable water from ATSR2 split-window channel data over land area
International Journal of Remote Sensing
(2003) - et al.
Angular variation of Land surface spectral emissivity in the thermal infrared: Laboratory Investigations on Bare Soils
International Journal of Remote Sensing
(1991) - et al.
Comparative performance of AVHRR-based multichannel sea surface temperatures
Journal of Geophysical Research
(1985)
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