The Science of Falling Snow

NASA Global Precipitation Measurement (GPM) Deputy Project Scientist Gail Skofronick-Jackson tells us about the science of falling snow and what the GPM mission will do to study this critical component of the Earth’s water cycle.

Their first experiment is the GPM Cold-season Precipitation Experiment (GCPEx) which is taking place right now in southern Ontario. NASA is working with Environment Canada.
Instruments on the ground at the Center for Atmospheric Research Experiments measure the quantity of snow, how fast it falls and how much water it holds. Radar and radiometers on the ground also get an up-close look at the snow as it falls from clouds to the surface. Meanwhile, two research planes, the University of North Dakota’s Citation and the Canadian National Research Council Convair 580, fly though the clouds measuring snowflake sizes and water content, temperature and cloud water. “They’ll do spirals so you can see all the way from the top of the cloud to the bottom of the cloud,” says Skofronick-Jackson.
Above the clouds at 33,000 feet, a third plane, NASA Dryden’s airborne laboratory DC-8, carries NASA Goddard-developed Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR) radiometer and NASA’s Jet Propulsion Laboratory-developed Airborne Precipitation Radar-2 (APR-2). Together these two instruments simulate the instruments that the GPM satellite will carry into orbit.