Extended Abstract (416K)P2.5
CERES operations for the Valencia Anchor Station in support of GERB validation efforts. CERES SCALES campaigns
Almudena Velazquez, University of Valencia, Valencia, Spain; and E. Lopez-Baeza, G. L. Smith, and Z. P. Szewczyk
The GERB (Geostationary Earth Radiation Budget) instrument launched in August 2002 on MSG-1 (METOSAT Second Generation) measures the energy emitted and reflected by the Earth.
Data from different satellite instruments are the only way to directly compare TOA data products, but direct comparison is not simple because the measurements depend on: viewing geometry and solar geometry, temporal and spatial sampling, the wavelengths measured and the spectral response of each individual instrument.
The similarity of the four CERES (Clouds and the Earth’s Radiant Energy System) instruments to GERB’s one offers a suitable opportunity to intercompare their respective measurements and derived products. However, while GERB observes the Earth from a fixed position, the Terra and Aqua satellites on which the CERES instruments are mounted are in sun-synchronous, near-polar orbits, thus obtaining data from a variety of different viewing angles by scanning the surface. Because of this scanning mechanism, CERES and GERB measurements may be co-located, that is viewing the same point on the surface at the same time, but obtained from different view points and therefore possessing different viewing and solar geometry. Detailed comparisons, at well characterised sites and involving other instruments would also provide a simultaneous and independent measure of the accuracy of the two instruments. This is exactly the role that the Valencia Anchor Station (39º34’15’’N, 1º17’18’’W, 813 m altitude) tries to play. Its final objective is to characterise a large area about the size of a GERB pixel (around 50 x 50 km2) situated in the Utiel-Requena Plateau, in Spain, about 80km North West of the city of Valencia. It is hoped that this site will be used in this latitude as a GERB and SEVIRI reference area.
The main objective of the Spanish Programme on Space Research SCALES (SEVIRI & GERB CaL/VaL Area for Large-scale field ExperimentS) Project is to develop a methodology for the validation of low spatial resolution satellite data and products mainly based on the use of the Valencia Anchor Station, around which 3D high resolution meteorological fields are obtained from the MM5 Meteorological Model. During the two GERB Ground Validation Campaigns developed so far (18-24 June, 2003, and 9-12 February 2004), CERES instruments on Aqua and Terra provided additional radiance measurements to support validation efforts. CERES instruments operated in the PAPS mode (Programmable Azimuth Plane Scanning) focusing the station. Ground measurements were taken by lidar, sun photometer, GPS precipitable water content, radiosounding ascents, Anchor Station operational meteorological measurements at 2m and 15m., 4 radiation components at 2m, and mobile stations to characterize non-homogeneities of such a large area. These activities were carried out within the GIST (GERB International Science Team) framework, during GERB Commissioning Period.
This paper describes the status of the methodology developed so far, the data obtained, and the application to the specific CERES PAPS observations as a preliminary stage previous to the final interpretation of GERB products.
Supplementary URL: http://www.uv.es/anchors
Poster Session 2, New and Future Sensors and Applications: Part 2
Monday, 20 September 2004, 3:00 PM-4:30 PM
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