GVS observations for statistical validation of GMP products will be made in a series of investigator-led field measurement campaigns, known as Extended Observation Periods, (EOPs). Several EOPs envisioned, each lasting several months, with each EOP punctuated by one or more Intensive Observation Periods (IOPs).

The first EOP and IOP will be executed prior to GPM launch. Some complement of GVS instrumentation will be fielded and run during each EOP. Additional instrumentation will be fielded during IOPs including, for example, aircraft-based instruments. EOPs will be conducted for a period of time in a given location. Periodically, field campaigns will move from one climatic regime to another, as determined by the GPM Project in consultation with members of PMM Science Team and other representatives of the atmospheric community.

Winter 2006-2007 Snowfall Field Campaign Prototype

The NASA GPM Project and the Precipitation Measurement Mission (PMM) Science Team will contribute to the Canadian CloudSat/CALIPSO Validation Programme (C3VP) during their Winter 2006-2007 field campaign. The campaign will take place in the vicinity of the Centre for Atmospheric Research Experiments (CARE) operated by the Meteorological Service of Canada. All members of NASA's PMM Science Team are covered by a "blanket" agreement that allows them full access to the C3VP data, subject to the C3VP Data Protocol.

The CARE facility is located about 80 km north of Toronto.

Early results from C3VP

Some early results are now available from a snowfall event that took place on December 6, 2006 over the CARE site. These results include data from a Snow Video Imager (SVI) and a pair of Parsivel disdrometers. Click on the links below to review these results.

+ Snow Video Imager results from IOP-2
+ Parsivel Disdrometer results from IOP-2)
+ 2-Dimensional Video Disdrometer (2DVD) from IOP-2
+ Parsivel Distrometer Results presented at the American Geophysical Union, Spring 2007
+ 2D video simulations of DSD and Ze for all C3VP significant snow days 6 Dec 2006 - 6 March 2007

The third C3VP Intensive Observation Period (IOP-3) took place during the period from January 17 through January 28, 2007. A series of instrumented aircraft flights were conduced during the IOP with the National Research Center of Canada's Convair-580 aircraft. The Convair-580 was instrumented with cloud microphysics instruments, radiometers, a lidar and radars, The aircraft complemented ground-based observations made at the CARE site as well as observations made by the King City C-band and X-band radars during the C3VP campaign.

In all, 9 snowfall events were observed during IOP-3. All of these events were observed by the King City radars, 8 of the events were observed by the University of Massachusetts 3-frequency (W-, Ka, and Ku-band) Advanced Multi-Frequency Radar (AMFR), and 3 of the events were also observed with Convar-580 overflights. Click here for a case summary of the dates, times, snowfall types, and instruments used during these 9 IOP-3 snowfall events.

Some of the NASA/GPM/PMM results from C3VP are now being published. Check on the links below for two recent conference papers.

+ NASA/GPM Participation in C3VP - Physical process studies in show
+ Disdrometer - Derived Z-S Relations in South Central Ontario, Canada

Goals for GPM participation in C3VP

The PMM Science Team and GPM communities will use C3VP for development of snowfall detection and estimation algorithms. Data sets are expected to help

Develop and validate models that convert the physical properties (shape, size distribution, density, ice-air-water ratio) of single snowflakes to their radiative properties (asymmetry factor, and absorption, scattering, and backscattering coefficients); and Relate the bulk layer radiative properties (summation of the single particle radiative properties over a discrete vertical layer) to calculated and observed passive microwave radiances and radar reflectivities. These models are central to physically-based snowfall retrieval methods, as well as the characterization of likely retrieval uncertainties. The NASA PMM and GPM Project will provide the following instrumentation to the C3VP field effort: High resolution triple frequency polarimetric radar measurements of snow/rainfall rate, particle type, and mass-content from the Advanced Multi-Frequency Radar (AMFR) operated by the University of Massachusetts. The AMFR is a scanning dual-polarimetric radar (hybrid basis) that operates at three frequencies and matched 0.7o beams: two (Ka and Ku bands) matched to the GPM Dual-frequency Precipitation Radar (DPR), and one (W band) matched to the CloudSAT radar Precipitation particle size distributions and shapes measured near the ground using a Two-Dimensional Video Disdrometer (2DVD) operated by Colorado State University, and by two Parsivel laser disdrometers operated by NASA Goddard Space Flight Center (GSFC). Some preliminary data from the Parsivel disdrometers are now available. Click here for more information.

Truck-mounted AMFR 3-frequency radar The Parsivel laser disdrometer measures snow and rainfall rates and size distribution + Convair-580 aircraft + View case summary

Access to C3VP data

Click here to see a summary table of data products from C3VP and how to access them. Data products from many investigators are available without restriction and can be accessed via the ftp sites identified in the table. Points-of-contact listed on the table can be consulted for more information on the data format and content, and on other details of data access and use. Data products with few or no restrictions include those from the following instruments and data sources:

• Snow Video Imager
• Parsivel disdrometer
• Tipping bucket gauges
• AMSU-B/MHS brightness temperatures
• Advanced Multi-Frequency Radar
• 2-Dimensional Video Disdrometer
• GOES imager and sounder
• WRF model output

A number of the products listed in the table were generated from instruments operated by C3VP Principal Investigators. These data products are available according to the conditions identified in the C3VP data protocol. The Points-of-contact identified in the table should be contacted for more information on data availability and access.

+ View C3VP data