Ground Validation

To improve the fidelity of radiometer-based rainfall estimates over land at short temporal and spatial scales, the Global Precipitation Measurement mission (GPM) requires development of physically-based passive microwave (PMW) precipitation retrieval algorithms anchored by dual-frequency precipitation radar (DPR) drop size distribution (DSD), hydrometeor profile and rain rate retrievals.

A complete understanding of the Earth’s hydrologic cycle necessarily dictates an ability to accurately quantify the global range of precipitation rates and types (rain, snow etc.). In turn, global observations of precipitation are most efficiently made from space. Great strides in the measurement of global tropical rainfall have occurred recently as a result of the NASA Tropical Rainfall Measurement Mission (TRMM).

n 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.

This document is a case summary of the dates, times, snowfall types, and instruments used during these 9 IOP-3 snowfall events.

Parsivel Distrometer Results presented at the American Geophysical Union, Spring 2007.

A series of measurements at the CARE site from the 2DVD instrument.

Overview of the Parsivel instrument:

• Measures size and fall velocity of hydrometeors
• Present weather sensor
• Sampling area: ~50 cm2, varies with drop diameter
• Number of size and velocity bins: 32 x 32 matrix
• Drop size range: 0.06-24.5 mm
• Velocity range: 0.05-20.8 m/sec
• Operation period at Wallops Island: Spring 2002 - present
• Manufacturer: OTT in Germany www.ott-hydrometry.de

The NASA Snowflake Video Imager obtained nearly continuous data from 1 Dec 06 thru 7 Mar 07.

This presentation contains a summary for the entire data set, which is sorted into (a) priority days selected by GSFC investigators, and (b) non-priority days.

The results are displayed in images of DSD(t), which reveal (a) the large variability of snowflakes sizes during events and (b) the intermittency of snowfall – even during intense storms.

Protocol for C3VP data.