Satellite observations of shallow cumulus coverage over the central United States: An exploration of land use impact on cloud cover

Abstract

A simple algorithm is presented which identifies cumulus clouds in visible and infrared satellite image pairs. The algorithm is applied to hourly pairs of the Geostationary Operational Environmental Satellite (GOES) to determine the relative frequency of daytime cumulus clouds over the central United States for two consecutive Julys: one drought (1988) and one control (1987). In both Julys, cumulus frequency decreased from southeast to northwest, against the gradient of elevation, but with the gradient of midday average relative humidity. On the scale of uplands and lowlands and even isolated ridges it tended to increase with elevation. During the drought in July, contrasts in vegetative cover were especially large. These contrasts tended to oppose contrasts in surface temperature inferred from satellite radiometers. They also tended to oppose contrasts in the frequency of shallow cumulus. Over central and southern Illinois, a flat to gently undulating, mostly rural plain, during July 1988, shallow cumulus clouds occurred more often over lightly vegetated than heavily vegetated landscapes. These clouds also tended to be relatively abundant near the larger urban centers. During the control July of 1987, fewer cumulus clouds were recorded.

Impacts of Land Cover and Greenhouse Gas (Ghg) Concentration Changes on the Hydrological Cycle in Amazon Basin: A Regional Climate Model Study

“…Different numerical and analytical studies have shown that the heterogeneities in the latent heat and sensible heat fluxes at the surface can produce strong mesoescale circulations (WANG et al 1998). These circulations affect significantly the structure of the PBL, the heat and moisture fluxes (LYNN et al, 1995) and the organization of the clouds (WETZEL et al, 1996;RABIN and MARTIN, 1996). The energy, moisture and momentum exchanges between the surface and the atmosphere are important components of the climatic system; therefore, due the changes in these fluxes, mesoscale circulations caused by natural and anthropogenic surface heterogeneity affect significantly the general circulation (PIELKE et al, 1998).…”

High-ResolutionGOES-8Visible and Infrared Cloud Frequency Composites over Northern Florida during the Summers 1996–99

“…The first results presented here are the cloud frequencies for 1715 UTC and focus on a small area within the region of analysis. This time is chosen to capture the distribution of small-scale cumulus clouds before the period of maximum deep convection is reached and the area is chosen to highlight small-scale features noted in Gibson and Vonder Haar (1990) and Rabin and Martin (1996).…”

Summer season land cover—Convective cloud associations for the midwest U.S. “Corn Belt”

“…A convection -surface relief association [cf. Rabin and Martin, 1996] is subordinate to that related to LU/LC and synoptic conditions: computed average values of the topographic roughness (i.e., small-scale slope change) are greatest in the 3 forest sub-areas, yet cloud development patterns differ by cover type among TAs (e.g., Fig. 3a, c).…”