Cal/Val Activities at the CIGSN Uardry Field Site, NSW, Australia in Support of the EO-1 Mission Fred Prata and Graham Rutter CSIRO Atmospheric Research David Jupp CSIRO Earth Observation Centre EOC Annual Science Meeting, Canberra 4-6 July, 2001 1
Aim of the Study To obtain a detailed assessment of the accuracy of Hyperion top-of-the-atmosphere (TOA) radiances Methodology Radiative transfer modelling Field measurements Inter-comparison with other sensors EOC Annual Science Meeting, Canberra 4-6 July, 2001 2
Analysis Derive hyperspectral TOA radiances using a radiative transfer model (Modtran 3) and atmospheric measurements Compare with measured ground-based spectra Compare with Hyperion TOA radiances Compare with other sensors (e.g. MODIS/ASTER/ASTR-2) Obtain assessment of Hyperion radiance calibration EOC Annual Science Meeting, Canberra 4-6 July, 2001 3
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Hyperion image of Uardry 9-Jan-2001 Uardry tower N 7 km (approx) Murrumbidgee river EOC Annual Science Meeting, Canberra 4-6 July, 2001 5
Field data CCD spectrometer measurements (1 nm, 500-900 nm) Solar and terrestrial radiation measurements Aerosol optical depth* Temperature and moisture profiles Ozone amount *Instrument malfunctioned EOC Annual Science Meeting, Canberra 4-6 July, 2001 6
Satellite data EO-1 overpass 9-Jan 2001 MODIS 1km and 250m data 9-Jan 2001 ATSR-2 1 km data Landsat-7 data 9-Jan 2001 ASTER data EOC Annual Science Meeting, Canberra 4-6 July, 2001 7
High-resolution groundbased spectra measured at many places during EO-1 overpass EOC Annual Science Meeting, Canberra 4-6 July, 2001 8
GPS locations and time of all spectra logged EOC Annual Science Meeting, Canberra 4-6 July, 2001 9
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BRDF Measurements and model fits at Uardry EOC Annual Science Meeting, Canberra 4-6 July, 2001 11
AEROSOL OPTICAL DEPTH MEASUREMENTS AT UARDRY April 1997 EOC Annual Science Meeting, Canberra 4-6 July, 2001 12
Radiosondes launched at the field site EOC Annual Science Meeting, Canberra 4-6 July, 2001 13
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Typical ranges and measurement errors in atmospheric parameters and surface reflectance for the Uardry field site EOC Annual Science Meeting, Canberra 4-6 July, 2001 17
Radiative Transfer Modelling Input surface and atmospheric measurements Input solar and viewing geometry Compute toa radiances compare Wavelength (nm) EOC Annual Science Meeting, Canberra 4-6 July, 2001 18
Satellite data sets Hyperion EO-1 MODIS 1 km data (36 channels) MODIS 250 m data (2 channels) ATSR-2 (1 km; 550, 670, 870, 1600 nm; 0 and 55 degrees) ASTER (9 channels, VNIR 15 m, SWIR 30 m) LANDSAT-7 EOC Annual Science Meeting, Canberra 4-6 July, 2001 19
Field site EOC Annual Science Meeting, Canberra 4-6 July, 2001 20
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MODIS 250 m data 9-Jan 2001 Field site EOC Annual Science Meeting, Canberra 4-6 July, 2001 22
Uardry Field Site 09-Jan-2001 Tower EOC Annual Science Meeting, Canberra 4-6 July, 2001 23
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Conclusions No measurable radiometric bias noticed 500-950 nm Below 480 nm hyperion appears to give radiances that are too low Good results obtained for inter-comparisons between Hyperion/Landsat-7 and MODIS Correct aerosol type and amount is crucial to getting accurate atmospheric corrections for hyperspectral data - but MODTRAN-3 models appropriately scaled seem to work well for Uardry (rural profile, low optical depths) EOC Annual Science Meeting, Canberra 4-6 July, 2001 33