Submitted to: BARC Poster Day
Publication Type: Abstract only
Publication Acceptance Date: 4/5/2006
Publication Date: 4/26/2006
Citation: Agam, N., Kustas, W.P., Anderson, M.C., Li, F. 2006. Utility and extension of land surface temperature sharpening technique (TsHARP)[abstract]. Abs. 01. BARC Poster Day. Interpretive Summary:
Technical Abstract: Continuous monitoring of surface energy fluxes in general and evapotranspiration in particular provide an important tool for precision agriculture management. It is, therefore, desirable to monitor these fluxes at small time intervals (optimally at least once a day) and at agricultural field size (usually length scale ~10-100 m). The rapid development of spaceborne systems during the recent decades made spatial data, required for energy fluxes monitoring, available at different spatial and temporal resolutions. To date, land surface temperature (LST), which is one of the fundamental inputs required for flux computations, is usually available at a temporal resolution of 1-2 revisits every 24-h daylight period, but at a nominal resolution of 1 km, which disables field-scale monitoring. Sharpening LST data by disaggregating each pixel into field-scale sub-pixels was found to be possible, with deterioration in temperature accuracy as sub-pixel size is reduced. The objective of this research is to examine the utility and the extension of the sharpening technique (TsHARP) proposed by Kustas et al. (2003)*. Data were used from the 2002 Soil Moisture-Atmosphere Coupling Experiment (SMACEX02) conducted over the Walnut Creek Watershed located in the upper Midwest corn and soybean production region of Iowa. Four dates during the period of rapid soybean and corn growth for which either airborne multispectral imagery (June 16, July 1, thermal spatial resolution of 6m) and/or Landsat TM images (June 23, July 1 and July 8, thermal spatial resolution of 60-120m) are available were analyzed. The original pixels were aggregated to form 960 m pixels (to mimic thermal data currently available from MODIS) and were then disaggregated following the TsHARP technique to form 60, 120, and 240 m sub-pixels. The TsHARP outputs were compared to the original LST data. The results indicate that sharpening LST to field scale sub-pixel resolutions for enabling surface energy flux monitoring for this region, with the currently available lower resolution data, may enhance the existing LST data, with increase of RMSE with decreased pixel size. Average (±std) RMSE of 1.55 (±0.45), 1.27 (±0.43) and 0.99 (±0.34) oC for the 60, 120 and 240 m resolutions respectively were found. This suggests that higher resolution LST data is still valuable at all times and crucial under certain conditions. Kustas, W.P., Norman, J.M., Anderson, M.C., French, A.N. 2003. Romote Sensing of Environment, 85, 429-440.