Improved land surface temperature retrieval method for the small satellite Flying Laptop
- Paper number
IAC-08.B1.4.9
- Author
Ms. Ursula Kirchgäßner, University of Stuttgart, Germany
- Coauthor
Mr. Toshinori Kuwahara, University of Stuttgart, Germany
- Coauthor
Dr. Maria von Schoenermark, University of Stuttgart, Germany
- Year
2008
- Abstract
This paper describes enhanced algorithms for land surface temperature retrieval by means of combinig the split-window method with the multi-angle method, employing a large number of angles between nadir and 60 degrees zenith angle. The small satellite Flying Laptop, with a mass of about 120 kg, is a technology demonstration and earth observation satellite, currently being developed at the Institute of Space Systems (Institut für Raumfahrtsysteme: IRS), Universität Stuttgart. The body-mounted scientific payload systems include the Thermal Infrared Camera System with a 450 mm diameter cassegrain system, achieving a ground sampling distance of about 100 m and a swath width of 32 km. The system will be equipped with a filter wheel featuring two filters, ranging from 8.0 to 9.2 µm and from 10.2 to 12.6 µm respectively, and a blackbody for in-orbit calibration. The attitude control system of the satellite permits arbitrary pointing angles, with an absolute pointing accuracy of less than 7 arcseconds and with a relative pointing knowledge within 2.5 arcseconds.
This combination of bi-spectral camera system and multi-angle observation capability offers a means of improving land surface temperature retrieval. In order to investigate the utility of the prospective observations, data has been modelled numerically for a wide range of atmospheric properties, using the radiation transport model MODTRAN. Ground temperature was modelled ranging from 270 K to 310 K, and emissivities were set to values typical for vegetation, from 0.96 to 1. Especially atmosperic water vapour content was varied in a wide range from near zero to over five g/cm 2 water column. In the numerical model multiple scattering was disregarded and only cloudfree atmospheres were considered. The resulting datasets were analysed by linear regression and a number of algorithms for temperature retrieval have been derived, depending on available angles: Up to 12 zenith angles from nadir to 60 degrees were employed in each algorithm. The multi-angle method improves accuracy of the retrieved temperature compared to the employment of the split-window method only, especially for very humid atmospheres. Even without accounting for emissivities, a standard deviation below one Kelvin can be achieved.
- Abstract document
- Manuscript document
IAC-08.B1.4.9.pdf (🔒 authorized access only).
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