The extensive cirrus record recorded 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.

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.