The Impact of Cloud and Radiation on the Great Plains Climate Change During 1981-2003

Relationships of surface air and soil temperature changes have been compared to downward solar radiation and cloud fraction over the Great Plains (latitudes of 37°N to 49°N, and longitudes of 95°W to 104°W). Twenty-three years of surface meteorological data have been collected, including surface air and 10 cm soil temperatures and downward solar flux from the High Plains Regional Climate Center (HPRCC) since 1981. The daily mean values of meteorological data within the states of Kansas, Nebraska, South Dakota, and North Dakota have been binned and averaged to 0.5-degree latitude intervals to study temporal and latitudinal variations of surface air and soil temperatures, as well as their correlations with downward solar flux. Preliminary results from this project have demonstrated that the surface air and soil temperatures have increased during the 1981-2003 period over the Great Plains. When broken down by latitude, the air temperature change has increased from nearly 0°C at 37°N to 1.7°C at 49°N, and the soil temperature change increased about 2.7°C. The downward solar flux has generally decreased during the 23-year period, but the downward solar flux change increases with latitude: -38 Wm-2 at 37°N and 18 Wm-2 at 49°N which is positively correlated to the air and soil temperature changes. The cloud fractions from International Satellite Cloud Climatology Project (ISCCP) during the 1983-2001 period have been used to study the impact of clouds on the surface radiation and temperatures. The Department of Energy Atmospheric Radiation Measurement (DOE ARM) downward solar fluxes over southern Kansas have been used to determine the overall quality of the results.