For the first time, scientists have three-dimensional snapshots of raindrops and snowflakes around the world, thanks to the joint NASA and Japan Aerospace Exploration Agency Global Precipitation Measurement (GPM) mission. With the new global data on raindrop and snowflake sizes, scientists can improve rainfall estimates from satellite data and numerical weather forecast models.
The mission will improve preparation efforts and provide better understanding of extreme weather events.
"The drop size distribution is one of many factors that determines how big a storm will grow, how long it will last and how much rain it will ultimately produce,” said Joe Munchak, research meteorologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We’ve never been able to see how water droplet sizes vary globally until now."
In order to accurately know the amount of precipitation falling in a storm, scientists need to understand the ratio of large drops to smaller or medium-sized drops. Previously, researchers had to make assumptions of the ratio; earlier studies were conducted in isolated locations and global data was limited, said Munchak.
“Without knowing the relationship or the ratio of those large drops to the smaller or medium sized drops, we can have a big error in how much rain we know fell and that can have some big implications for knowing long term accumulations which can help with flash flood predictions,” said Munchak.
With GPM’s three-dimensional snapshots of drop size distribution, scientists can also gain insight into the structure of a storm and how it will behave.
Also: Learn about NASA's Snowflake Growth Simulation.