The extensive cirrus occurences observed in the Atmospheric Radiation Measurement (ARM) data is being used to investigate the sensitivity of certain cirrus properties to the large-scale meteorology. Using four years of millimeter cloud radar (MMCR) data from the Southern Great Plains (SGP) site, a statistical analysis of effective radius, ice water path, emissivity, and optical thickness is performed for each cloud event. Variations in cloud property statistics are then shown on a seasonal and inter-annual time scale. Seasonal variations are observed in effective radius possibly due to different generating mechanisms. Typical warm and cold season cases are shown using the NSDL Atmospheric Visualization Collection.

These event statistics also allow us to explore relationships between the statistical properties of cirrus events to other parameters. Currently we are using the NCAR/NCEP reanalysis data to represent the large-scale meteorology of the SGP region during the study period. Using reanalysis data we show the meteorological anomalies during cirrus events from the seasonal and inter-annual means. These anomalies are found by taking the difference between the mean meteorology occurring on days when cirrus events are present, and the seasonal and inter-annual meteorological means. Results of this analysis and implications for the parameterization of cirrus in climate models will be discussed in this paper.