Monday, 10 January 2005
Diurnal Cycle of Summertime Deep Convection over North America: A Satellite Perspective
High-resolution (0.1°x0.1°) geostationary satellite infrared radiances at 11 micro in combination with gridded (2.5°x2.0°) hourly surface precipitation observations are employed to document the spatial structure of the diurnal cycle of summertime deep convection and associated precipitation over North America. Comparison of the diurnal cycle pattern between the satellite retrieval and surface observations demonstrates the reliability of satellite radiances for inferring the diurnal cycle of precipitation, especially the diurnal phase. Based on the satellite radiances, we find that over most land regions, deep convection peaks in the late afternoon and early evening, consistent with the strong diurnal cycle of land surface temperature. However, strong regional variations exist in both the diurnal phase and amplitude, implying that topography, land-sea contrast, and coastline curvature play an important role in modulating the diurnal cycle. Examples of such affects are highlighted over Florida, the Great Plains, and the North America monsoon region.