Impact of Soil Moisture and Vegetation Distribution on July 1989 Climate Using a Regional Climate Model
Abstract
Anyone who has ever walked from a closed forest into an open meadow knows that vegetation can have a significant effect on the atmosphere. Additionally, anyone who has tried gardening is also aware of the role the atmosphere can have on the success or failure of that hobby. It is fairly well understood, at least in a broad sense, how the earth's surface and the planetary boundary layer interact on the local scale. What is less known is how changes in the characteristics of the earth's surface feed back up to larger scales such as regional or global. This has important consequences in understanding how changes in surface characteristics due to natural or anthropogenic causes impact the climate. Perhaps even more important, is understanding the sensitivity of our parameterizations of atmosphere-landsurface interactions to the specification of the earth's surface. The Regional Atmospheric Modeling System has been modified for use in regional climate studies (CLIMRAMS). The model has been verified for July 1989 and has shown that the simulated screen height temperatures over 70% of the model domain were within 1^circC of observations. The simulated precipitation was generally within a factor of two of the observations. The United States average daily precipitation was 2.3mmcdot day^{-1} while the simulated rate was 1.5mmcdotday ^{-1}. The model was also applied to sensitivity studies to assess the impact of soil moisture and vegetation distribution. Results from the soil moisture studies indicate that the initial specification of the soil moisture content can have small but significant effects on screen height quantities and precipitation for time periods up to a month. Results from a homogeneous grassland study demonstrate that regionally there can be cooling due to increased albedo or warming due to decreased latent heat flux. Finally, CLIMRAMS was applied to study the effect of lost forest and grassland ecosystems to agricultural usage. The results of the final study suggest the possibility that the current landuse has caused summertime surface conditions to be warmer and drier than the natural landscape would indicate.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- January 1995
- Bibcode:
- 1995PhDT........97C
- Keywords:
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- PRECIPITATION;
- Physics: Atmospheric Science; Biology: Ecology; Hydrology