Land‐surface‐atmosphere interactions for the 1988 summer drought in the Mid‐west USA are studied at climatic scales (104 km2; >5 days) using polar orbiter satellite radiance information on vegetation activity and cloud conditions. The emphasis is on documenting the occurrences of ‘organized’ land‐cover types and cumulus convection, and evaluating their mutual associations. For purpose of comparison, similar analyses are performed for the more moisture sufficient (non‐drought) summer of 1987. The satellite retrievals and analysis methods are calibrated using station meteorological data on precipitation and surface moisture, and also land‐cover maps. In early summer (June) 1988, Mid‐west USA land surfaces were generally highly stressed (high shortwave reflectance, high surface temperatures), particularly for the Corn Belt. Moreover, the spatial variation of the land‐cover signal was greater than in June 1987, and also when compared with later that summer (August 1988). Statistical analysis suggests a significant role for the land surface conditions of early summer in the spatial patterns of deep convection over the remainder of the season. This involves generally higher (lower) frequencies of convective cloud days for surfaces having a high relative density of forest vegetation (crops). Because broadly similar results are obtained for the summer of 1987, the possibility exists that the vegetation‐convective‐cloud interaction may be a feature of Mid‐west USA summer climate. The diurnal dependence of cloud‐forming processes for agricultural and natural vegetation regions is assessed using GOES cloud imagery at high temporal resolution for a “typical” convective day in early summer 1988. Associations with station radiosonde data support the hypothesis that spatial differences in land cover influence the generation and timing of convective cloudiness for the Mid‐west region.
All Science Journal Classification (ASJC) codes
- Atmospheric Science