The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation

Miscellaneous · Wed Jan 01 00:00:00 EST 1992

OSTI ID:6192072

Yang, R

The influence of variations of vegetation and soil moisture on surface weather and atmospheric circulation is studied through the use of the Simple Biosphere Model (SiB) and the Center for Ocean-Land-Atmosphere interactions (COLA) GCM. Tests for the SiB sensitivity to the conversion of the forest to other short vegetation or bare soil were performed at Amazonian and Great Plains sites, and a North Wales spruce forest site respectively. The results show that deforestation has a significant influence on the local surface energy budget and surface weather. The influence is especially prominent at the Amazon and Great Plains sites, and larger in summer than in other seasons. The influence on the partitioning of surface incoming radiative energy is generally constrained by the local atmospheric boundary condition. The sensitivity of the COLA GCM to changes in initial soil wetness (ISW) is determined by repeating three 10-day model integrations with the same initial and boundary conditions as the control runs except the values of ISW, which are revised at 69 model grid points covering much of the continental U.S. It is found that the relations between the changes in the 5-day mean forecast surface air temperature/surface specific humidity and the changes in ISW depend upon vegetation type and the values of ISW, and can be approximated by regression equations. These relations are also confirmed with independent data. With the ISW revised based on these regression equations the surface forecasts of the revised runs are consistently improved. The spatial scale of the ISW anomaly determines the degree and range of the influence. The influence of a small regional ISW change is mainly confined to the local region and to low atmospheric levels. The influence on surface fluxes is strong and persists for more than one month, but the effects on precipitation are relatively weak, changeable, and complex, particularly when an interactive cloud scheme is used.

• Research Organization: Maryland Univ., College Park, MD (United States)
• OSTI ID: 6192072
• Resource Relation: Other Information: Ph.D. Thesis
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CLIMATIC CHANGE
BOUNDARY LAYERS
GENERAL CIRCULATION MODELS
EARTH PLANET
DEFORESTATION
ENERGY BUDGETS
SOILS
MOISTURE
ATMOSPHERIC CIRCULATION
BIOSPHERE
PLANTS
VARIATIONS
WEATHER
LAYERS
MATHEMATICAL MODELS
PLANETS
540210* - Environment
Terrestrial- Basic Studies- (1990-)
540110