Normalization and comparison of surface temperatures across a range of scales

The Southern Great Plains 1999 (SGP99) Experiment, conducted in Oklahoma, July 8-21, 1999, provided an opportunity to observe spatial and temporal variations in surface temperature. During the experiment, aircraft (Passive/Active L/S-band airborne sensor) and satellite [Advanced Very High Resolution Radiometer (AVHRR) and TIROS Operational Vertical Sounder (TOVS)] sensors collected surface temperature that was compared to in situ observations over the same time period to determine the accuracy and consistency of surface temperature measurements at different spatial resolutions using remotely sensed data. In addition, in situ surface temperature was observed in a 400×400 m field at various spatial grid spacing: 50 m, 10 m, and 1 m in order to quantify the variability of the spatially distributed behavior of surface temperature during a drydown period. Average differences between the in situ surface temperature observations and the aircraft and satellite sensors utilized during this study ranged from 0.7°C (AVHRR High Resolution Picture Transmission) to more than 20°C (AVHRR Global Area Coverage (GAC), TOVS). We have shown that the temporal adjustments of the remotely sensed surface temperatures (from aircraft and satellite sensors) shows a better comparison to in situ ground data. A ratio was set up using information derived from a mosaic land surface model to temporally locate the various estimates of surface temperature. The corrected surface temperature comparisons decreased the average differences (with in situ) to as much as 78% [AVHRR (GAC)] and as little as 6% (TOVS). The average difference between remotely sensed and in situ observations was around 48%.