Comparing Satellite, Aircraft, and Ground Reflectance Measurements for Arid Rangelands.

Understanding land surface reflectance in the visible and near infrared (VNIR) and shortwave infrared (SWIR) wavelengths is fundamental for determining the contribution that remote sensing can make to our understanding of land surface processes and the properties affecting vegetation change and the heat and water balances at landscape scales.  This study compares remotely sensed reflectance data collected for arid rangelands at the Jornada Experimental Range in the northern Chihuahuan desert of southern New Mexico USA.  The data are from different sensors/platforms and over a range of plant communities for several dates.  In situ ASD (Analytical Spectral Devices) spectroradiometer VNIR and SWIR reflectance data (0.35 to 2.5 micrometers) for May 12, 2001, October 6, 2002, and May 2, 2003 were analyzed and integrated to match the first 21 MASTER (MODIS/ASTER Airborne Simulator) and the 9 ASTER (Advanced Spaceborne Thermal Emission Reflection Radiometer) VNIR and SWIR  bands.  The results for three different plant communities (grass, shrub-grass transition, and shrub) were compared to airborne MASTER and spaceborne ASTER reflectance data collected for the same plant communities and dates.  A strong positive correlation was observed indicating that the three sensors were measuring similar reflectance values for the three dates and plant communities.  Reflectances measured in the VNIR were highly related for the three sensors.  Reflectances were highest from the shrub and shrub-grass communities and lowest from the grass community and were related to the amount of plant cover.