Figure 0. Radar beam heights over the Four Corners region. Beam heights exceed 5km or 15,000 ft in the area, thus overshooting storm tops. Larger Image
Figure 1. Mosaic of regional NWS NEXRAD radars showing reflectivity on August 5th 2010 at 1600 UTC (1000 MDT). Larger Image
Figure 2. Same as Figure 1 but with the SMARTR added. Larger Image
Figure 3. One-hour rainfall accumulations derived from the NEXRAD-only mosaic valid at 1700 UTC (1100 MDT) on August 5th 2010. Larger Image
Figure 4. Same as Figure 3 but with the SMARTR added. Larger Image
A collaborative project for observing details of thunderstorm rainfall in southwest Colorado
Objective
This project seeks to research improvements in remotely sensed rainfall estimates in southwest Colorado. Southwest Colorado resides in a region not optimally observed by surrounding NWS radars. The NWS WSR-88D radars often see only the upper parts of thunderstorms leaving uncertainties as to surface rainfall rates. An emphasis is placed on flash flood monitoring in and around the San Juan Mountains and determining the utility of real-time radar information for improving precipitation monitoring. NSSL will deploy the C-band dual-polarization Shared Mobile Atmospheric Research and Teaching Radar (SMART-R) to collect data in southwest Colorado. Seventeen recording rain gauges were installed by the National Center for Atmospheric Research to help calibrate the radar data. The University of Colorado has deployed two optical disdrometers and a vertically-pointing micro-radar at Ft. Lewis College. These instruments will be used to validate radar rainfall estimates. Near-realtime SMART-R radar data will be transmitted to the NWS WFO Grand Junction, CO and Albuquerque, NM for comparisons with operational observations. This field project will be conducted during August 2010 with a focus on storms occurring over the San Juan Mountains. The NSSL Q2 project
will be a test bed platform for the merging of SMART-R radar data with data from surrounding WSR-88D radars.
Project Goals
Explore the use of a C-band research mobile Doppler radar with dual polarization for observing details of thunderstorms in southwest Colorado. Supplemental radar data are expected to aid in local hazard warnings and benefit emergency response efforts to protect lives and property.
- Demonstrate the potential of a gap filling radar in Southwest Colorado
- Document the spatial and temporal characteristics of heavy rainfall
- Provide near real-time data for NWS assessment and demonstrate the utility of a local radar for improved detection of flash floods
- Advanced evaluation of dual-polarization rainfall algorithms (post-analysis)
Deployment:
The SMART-R site location is located on Bridge Timber Mountain, southwest of Durango at ~8250 ft above sea level. The Southern Ute Indian Tribe has graciously granted access to this valuable location. Radar coverage is optimized to scan over upper basins of the primary streams and rivers of the San Juan Mountains. However, the site allows a panoramic view of the entire region out to 250 km range.
Data application methodology:
SMART-R radar processing for use by the NWS.
Overview:
The NSSL will provide supplementary rainfall rate fields to the Flash Flood Monitoring and Prediction system used by the NWS for operational flash flood warnings. Data will be provided electronically in near-realtime.
Description:
SR2 data will be transmitted via a Motosat satellite uplink or cell phone modem to a server at the NSSL. The data will be processed and merged into NSSL's next-generation quantitative precipitation estimation system (Q2). The Q2 system will a) convert SR2 radar data from polar coordinates to a 1 km x 1 km grid. A separate quality control algorithm will be used to remove ground targets and other contaminates. Then the gridded SR2 data is merged with surrounding radar. A dynamic radar-rain rate relation (i.e., Z-R) algorithm will use environmental data to assign a special rainfall rate to each grid point. The final gridded field of mosaiced rain rates from regional radars will be sent to WFO GJT and ADQ offices via LDM, a standard communications protocol, for input into the Flash Flood Monitoring and Prediction - Advanced (FFMP-A) system. FFMP-A is an advanced version of FFMP that can ingest gridded data from multiple radars while FFMP ingests data from only a single radar. FFMP and FFMP-A uses sub-basin rainfall rate thresholds for warnings.