Global Precipitation Measurement (GPM) Front Range Pilot Project

Thunderstorm over Lafayette, Colorado.
Thunderstorm over Lafayette, Colorado.



The Global Precipitation Measurement (GPM) program is being designed by NASA and Japan's space agency, JAXA, to measure precipitation on a nearly global basis using radars and radiometers aboard an international constellation of orbiting satellites. Launch of the core satellite, carrying a dual-wavelength precipitation radar, is expected near the end of this decade. The program will greatly extend the spaceborne coverage and capabilities of the present Tropical Rainfall Measuring Mission (TRMM). In addition to obtaining measurements of precipitation with an unprecedented combination of accuracy and spatial coverage, GPM will address many scientific questions related to global climate change, such as whether the Earth's hydrologic cycle is accelerating, as suggested by some climate models.

A major facet of GPM is the establishment of ground-based sites to complement and validate the satellite measurements. Oklahoma and Kwajalein Island are likely locations for the two ground validation (GV) supersites to be sponsored by NASA. The appropriate suite of instrumentation for each site is currently under consideration. As an early aid to GV-site planning, a pilot field project in 2004 will test measurement techniques in Colorado's Front Range area, where many of the types of instruments under consideration are already congregated. These include scanning polarimetric weather radars and vertically profiling Doppler radars. The two kinds of radar systems complement each other, providing independent means (polarimetric and Doppler) for estimating the raindrop size parameters that are vitally important for properly interpreting the future satellite-based rain estimations. The scanning radars offer wide area coverage, while the profilers provide continuous soundings of the precipitation overhead and an intermediate scale connection between the tiny sample volume of gauges and the huge sample volume of satellite remote sensors. Rainfall estimation attributes of various wavelengths will be compared in the pilot project. The field work is scheduled for May and June in the area between Denver and Greeley, Colorado.

Project Map

Project Area Map

Project Site Coordinates

Site Latitude (N) Longitude (W) Altitude (MSL) Azimuth/Range
from Erie-1 (deg/km) from CHILL (deg/km)
Erie-1 40° 05' 56" 105° 02' 06" 1503 m 0/0 221/51.0
BAO 40° 02' 35" 105° 00' 19" 1587 m 158/6.7 215/54.5
Platteville 40° 10' 58" 104° 43' 35" 1523 m 070/28.5 190/30.5
CHILL 40° 26' 47" 104° 38' 14" 1432 m 041/51.0 0/0

Site Instrumentation

At Greeley CHILL S-band Polarimetric Radar (CSU) description, data/images
At Erie-1 NOAA/ETL X-band Polarimetric Radar (ETL) description, data/images
At BAO (Visitors Center) S-band Precip Profiler (ETL) description, data/images
449-MHz Profiler - quarter scale (ETL) data/images
915-Mhz Boundary Layer Profiler (ETL) data/images
Joss-Waldvogel Raindrop Disdrometer (ETL) data
Surface Meteorology, including rain gauge (ETL) data/images
At Platteville S-Band (2835 MHz) Precipitation Profiler (AL)
449-MHz Profiler (NOAA Network) data/images
Joss-Waldvogel Raindrop Disdrometers (AL & CU)
Rain gauge (AL & CU)
Ceilometer (AL & CU)
Additional Rain gauges data