Ground Validation

GPM's Snow Ground Validation Underway

The GPM Cold-season Precipitation Experiment (GCPEx) to measure falling snow is currently underway in Ontario, Canada. The field campaign, which runs from January 17 to February 29, 2012, is designed to improve satellite estimates of falling snow and test ground validation capabilities for GPM. Learn more about GCPEx: Airborne Campaign to Measure Falling Snow (press release) GCPEx Overview GCPEx Campaign Blog Ground Validation Image Gallery GPM on Twitter GPM on Facebook

Day 1: GCPEx Commences

Today the GPM Cold-weather Precipitation Experiment (GCPEx) officially began, and instead of snow, all that came down from the sky was cold rain. Location of the GCPEx experiment Fortunately Environment Canada's Weather Office says significant snow (and, yes, freezing rain, too) is on the horizon for Southern Ontario, where ground stations instrumented to within an inch of their lives are situated. The main GCPEx ground station is at the Centre for Atmospheric Research Experiments (CARE) in Egbert, Ontario, about 44 miles (70 km) north of Toronto and about 27 miles (44 km) southeast of Lake
GCPEx logo on falling snow background
By Ellen Gray, NASA Goddard Space Flight Center Original Press Release (published 1/12/12) Beginning Jan. 17, NASA will fly an airborne science laboratory above Canadian snowstorms to tackle a difficult challenge facing the upcoming Global Precipitation Measurement (GPM) satellite mission -- measuring snowfall from space. GPM is an international satellite mission that will set a new standard for precipitation measurements from space, providing next-generation observations of worldwide rain and snow every three hours. It is also the first mission designed to detect falling snow...
Document Description

A prototype Validation Network (VN) is currently operating as part of the Ground Validation System for NASA’s Global Precipitation Measurement (GPM) mission. The VN supports precipitation retrieval algorithm development in the GPM prelaunch era. Postlaunch, the VN will be used to validate GPM spacecraft instrument measurements and retrieved precipitation data products.

Scientists Gather in Denver for the 2011 PMM Science Team Meeting

Over 150 scientists from 10 different countries are meeting in Denver, Colorado, to discuss rain and snow and how to measure them from space. Only once a year members of the Precipitation Measurement Missions (PMM) Science Team come together to discuss the science surrounding both the current Tropical Rainfall Measuring Mission (TRMM) and the upcoming Global Precipitation Measurement (GPM) mission that will launch in 2014. The four-day meeting opened on Monday, November 7th with a focus on the mission status for both TRMM and GPM, and continues with breakout sessions, scientific presentations
GPM flying over Earth with a data swath visualized.
A key component of the TRMM project is the Ground Validation (GV) effort which consists of collecting data from ground-based radar, rain gauges and disdrometers. The data is quality-controlled, and then validation products are produced for comparison with TRMM satellite products. The four primary GV sites are Darwin, Australia; Houston, Texas; Kwajalein, Republic of the Marshall Islands; and, Melbourne, Florida. A significant effort is also being supported at NASA Wallops Flight Facility (WFF) and vicinity to provide high quality, long-term measurements of rain rates (via a network of rain...

NPOL Ground Validation Instrument

The NPOL instrument, a large circular radar dish under a blue sky
Image Caption
The NASA NPOL radar is a research grade S-band, scanning dual-polarimetric radar.

The NPOL underwent a complete antenna system upgrade in 2010 and is one of two fully transportable research-grade S-band systems in the world.  It is used to make accurate volumetric measurements of precipitation including rainfall rate, particle size distributions, water contents and precipitation type.