Precipitation profiling from vertically-looking ground-based radar profilers operating at frequencies of 915- and 2835-MHz have been demonstrated to be useful tools in several field campaigns during the past decade. When combined with a surface disdrometer and a nearby scanning radar, the calibrated profiling radar provides high resolution details of the precipitation vertical structure while the scanning radar provides the horizontal context of the precipitation relative to the profiler site. Profiling radars provide detailed information of reflectivities and drop-size distributions that are essential for quantitative precipitation estimation (QPE). One role that profiling radars have in QPE is monitoring the calibration of the scanning radar reflectivity used to map the precipitation over a large area. The concept of up-scaling uses a surface disdrometer to calibrate the profiling radar which is then used to calibrate the scanning radar. This method of up-scaling the reflectivities observed by the surface disdrometer to the scanning radar reflectivities eliminates some of the uncertainties of Z-R relationships inherent in surface rain gauge to scanning radar calibrating and monitoring techniques.
During the past decade Doppler radar profilers that operate near 1 GHz and 3 GHz have been developed at the NOAA Aeronomy Laboratory for use in dynamics and precipitation research. The profilers have been used extensively in numerous field campaigns during the past decade. In the presence of precipitating clouds, backscattering from hydrometeors is dominant and the Doppler velocity provides a measure of the fall velocity of hydrometeors. Profiler observations yield time height cross-sections of equivalent reflectivity, Doppler velocity and spectral width that illustrate the evolution of precipitating clouds systems. The vertical structure of these parameters has been used to classify the precipitating cloud systems into several different categories. These observations document the prevalence of deep anvil cloud systems over the Pacific warm pool region. They also show the relative abundance of rainfall from stratiform and convective components of precipitating cloud systems and the continuous observations reveal the diurnal evolution of the precipitating clouds over the profiler. The profiler observations provide important information for the calibration and validation of precipitation measurements by other instruments and platforms. For example, direct comparisons of profiler reflectivities with scanning radar reflectivities provide a direct means for calibration of scanning radars. The profilers are calibrated with a collocated disdrometer. An important objective of the profiler observations is to retrieve drop-size distributions and to determine the variability of the drop-size distributions in diverse precipitating cloud systems. Recent developments provide optimism that drop-size distribution retrievals can be made by profilers operating at 1 GHz or 3 GHz without complementary measurement of vertical air motions.
The U.S. NOAA Profiler Network operated by the Forecast Systems Laboratory for more than a decade represents the culmination of several decades of research and development of wind profiling Doppler radars. The NOAA Profiler Network is comprised of 35 tropospheric wind profilers (404/449 MHz) mostly located in the central United States. The infrastructure, built over the years for the NOAA Profiler Network has the flexibility and capacity to handle many other profilers in addition to the 35 NOAA Profiler Network systems. With recent advances in computers, networking and communication technologies, real-time profiler data can be acquired from almost anywhere on the globe. Data from remote sites are submitted to quality control and placed onto the Global Telecommunication System. Currently the Forecast Systems Laboratory is receiving data from about 80 sites in the continental U.S., Alaska, Canada, and along the equator west from South America. The data are routed to operational forecast centers where the data are used in a variety of numerical weather prediction models and also distributed to the local forecast offices to tailor model guidance to local conditions. The data are also placed on the Forecast Systems Laboratory web site http://www.profiler.noaa.gov. Here the data may be viewed in many graphical forms and are also available for downloading to a user’s site in numeric format.
With their high vertical and temporal resolution, vertically-pointing profilers offer valuable information about the vertical structure of precipitating cloud systems. The observed vertical structure of the precipitating cloud is related to the latent heating profile in the cloud system. The different precipitation regimes (e.g., convective, stratiform, and transitional precipitation) can be identified by diagnosing the profiler resolved vertical structure of reflectivity, mean Doppler velocity, and turbulence. The classifications based on these vertical profiles are important for estimating the frequency and percent occurrence of the precipitation regimes.
Conference Committee Involvement (2)
Microwave Remote Sensing of the Atmosphere and Environment IV
9 November 2004 | Honolulu, Hawai'i, United States
Microwave Remote Sensing of the Atmosphere and Environment III
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