Moist and dry layer retrievals using S-band radar

A technique utilizing clear-air Bragg scatter returns from S-band PPI scans was developed to locate local maxima and minima in the mean relative humidity vertical profile. The horizontal area represented by these average profiles varies as a function of elevation angle, scan sector, and altitude, but in general can range up to 45 km distance from the radar. It will be demonstrated that this technique can be used in both marine and continental environments. Advantages of this technique include near “real-time” processing capability, high temporal resolution, and an independent estimate for each elevation angle scanned ≥ 3º in the PPI volume scans. Although coarse, these measurements reflect the mesoscale average of what is largely small scale moisture variability. While notably absent from past data sets, such measurements are much needed both for improving short term weather forecasting as well as for comparison with and validation of LES models. While no information is retrieved as to the magnitude of each RH maxima and minima detected, these measurements combined with sounding data have the potential to significantly impact both our understanding as well as the short term predictability of many atmospheric phenomena. Cases using NCAR's SPol radar from the Rain in Cumulus over the Ocean (RICO) and the International H2O Project (IHOP) will be presented with validation provided by soundings (RICO) and Raman lidar (IHOP).