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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Hydrology and Remote Sensing Laboratory » Research » Publications at this Location » Publication #297286

Title: Reconciling diurnal features of thermal-andmicrowave-derived land surface temperature

Author
item Holmes, Thomas
item Crow, Wade
item HAIN, C - University Of Maryland
item Anderson, Martha

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 10/21/2013
Publication Date: 12/9/2013
Citation: Holmes, T.R., Crow, W.T., Hain, C., Anderson, M.C. 2013. Reconciling diurnal features of thermal-andmicrowave-derived land surface temperature [abstract]. Proceedings of the Fall American Geophysical Union, December 9-13, 2013, San Francisco, CA. 2013 CDROM.

Interpretive Summary:

Technical Abstract: Land surface temperature (T), a key ingredient for physically-based retrieval algorithms of hydrological states and fluxes, remains a poorly constrained parameter for global scale studies. The main two observational methods to remotely measure T are based on thermal infrared (TIR) observations and passive microwave observations (PMW). TIR is the most commonly used approach and the method of choice to provide standard T products for various satellite missions. It has found wide application, for example in energy balance approaches to retrieve land surface evapotranspiration. PMW-based T retrievals on the other hand are not as widely adopted for land applications; currently their principle use is in soil moisture retrieval algorithms. PMW and TIR technologies present two highly complementary and independent means of measuring T. PMW observations have a high tolerance to clouds but a low spatial resolution, and TIR has a high spatial resolution with temporal sampling restricted to clear skies. Furthermore, a combination of these T estimates with independent errors would inevitably reduce the overall uncertainty in estimating T. The need for improved T estimates at global scale for use in physical retrieval models of land surface parameters have motivated our work to understand the structural differences in the characteristics of the shape of the diurnal temperature cycle (DTC) as observed by PMW and TIR sensors. The ultimate goal of this work is to create a merged PMW and TIR temperature product that is spatially and diurnally continuous. This paper will report on recent progress in characterizing the main structural components of the DTC that explain differences in TIR and PMW estimates of T. Spatial patterns in DTC timing (phase lag with solar noon) have been calculated for TIR, PMW and compared to weather prediction estimates. Based on knowledge of DTC timing, which is relatively stable over the year, the DTC amplitude is studied in terms of spatial and temporal correlation between PMW and TIR. The nature of the temperature at the very surface layer of the land makes it difficult to combine temperature estimates between different methods. The skin temperature is characterized by a strong diurnal cycle that is dependant in timing and amplitude on the exact sensing depth and thermal properties of the vegetation. The results of this study present a significant step forward in reconciling the structural differences in T and thus prepare the way for a global merger of PMW and TIR T.