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.