Given by Dr. Phillip Chilson of the School of Meteorology at the University of Oklahoma:
Combined Observations of Precipitation Using Wind Profilers and Polarimetric Weather Radars
Phillip Chilson
The National Weather Service is preparing to implement a major upgrade to the network of Weather Surveillance Radars (WSRs) operated within the U.S. The main thrust of the upgrade will be to introduce polarimetric capabilities, which will have tremendous impacts on Quantitative Precipitation Estimation (QPE). Using radar polarimetry, it is possible to estimate the size distribution of precipitation particles and thereby obtain better estimates of the rainfall rate. Furthermore, polarimetric radars can be used to differentiate between various forms of precipitation (e.g., rain, sleet, hail, graupel, etc.) Wind profilers have also been widely used for studies and observations of precipitation. They provide valuable information regarding the vertical structure of the precipitation and Doppler spectra from the wind profilers can be used to directly measure the drop size distribution (DSD) as a function of time and height. In order to extract DSDs from Doppler spectra, however, one must know the vertical component of the wind. This can pose a serious challenge, especially at UHF. We propose a method through which complementary observations from wind profilers and polarimetric weather radars can be incorporated for the purpose of simultaneously investigating the vertical structure of precipitation and the three-dimensional wind field.
The technique is demonstrated by presenting complementary observations of a mesoscale convective systems observed in Central Oklahoma using a 404-MHz wind profiler with RASS and a polarimetric S-Band weather radar. The wind profiler is operated by the National Oceanic and Atmospheric Administration (NOAA) Global Systems Division (GSD) of the Earth Systems Research Laboratory (ESRL) and is located near Purcell, OK. The weather radar is KOUN operated by the NOAA National Severe Storms Laboratory (NSSL) in Norman, OK. The separation between the two sites is approximately 30 km. The distance is large enough to be well out of the ground clutter but close enough to provide good spatial resolution. At this range, the NSSL KOUN radar has a beamwidth of approximately 500 m and the lowest elevation angle samples about 250 m above the wind profiler. Such joint measurements are particularly timely considering that NOAA is planning to upgrade and possibly extend its network of wind profilers. The NOAA Profiler Network (NPN) will be converted over to 449-MHz; and, it is envisioned that the upgrade will provide more flexible operation and improved signal processing capabilities.
Tuesday, August 8 at 3:30pm in FL2-1001
|
