Comments on “Atmospheric Disturbance Caused by Human Modification of the Landscape”

Abstract

In a recent article published in the February 2001 issue of the Bulletin of American Meteorological Society, Weaver and Avissar (hereafter WA) investigated the response of the atmosphere to landscape heterogeneity to assess the importance of mesoscale fluxes of sensible and latent heat arising from differences in land use in the southern Great Plains. To do so they used the RAMS mesoscale model and a surface flux data set derived from observations and the Simple Biosphere Model. They selected six days for analysis based on the criterion that the study region located at the Department of Energy's Atmospheric Radiation Measurement Program's Cloud and Radiation Testbed (CART) was not obscured by clouds with obvious non-local origins. WA noted that mesoscale fluxes of latent heat on those six days were large, especially near and above the top of the boundary layer. They argued that regions of strong vertical motion that they associated with mesoscale fluxes were closely correlated with regions of precipitation on one of the six days they studied and with cloudy regions on two other days. From these findings, WA concluded that landscape heterogeneity arising from human influences can''significantly affect local weather and climate.'' They further concluded that the inabilitymore » to predict mesoscale fluxes is a serious failing of general circulation models (GCMs) used to predict climate change and that further studies in parameterizing such fluxes for use in GCMs is therefore necessary. In this paper we offer a somewhat different interpretation and perspective on the findings of WA.« less