Atmospheric scientists with NASA and the University of Washington chose a doozy of a week on the Olympic Peninsula to launch their four-month effort to measure precipitation and calibrate the super-sophisticated Global Precipitation Measurement (GPM) system.
The heart of the GPM system is an advanced satellite called the GPM Core Observatory, designed to measure rainfall and snowfall from space. If the system can be perfected, meteorologists and climatologists will have a fantastic tool for measuring precipitation where no ground-based instruments are located.
To improve the satellite system, ground-based radar and other equipment were moved to remote areas of the Olympic Peninsula to take measurements (see video below). Meanwhile, aircraft flying above, below and inside the clouds were taking their own readings.
The program, called Olympex for Olympic Mountains Experiment, is impressive. Researchers chose the west side of the Olympics because that’s where storms arrive from the Pacific Ocean, laying down between 100 and 180 inches of rainfall each year. Sure, these folks were looking for rain, but did they really know what they were getting into?
On Friday, a Doppler-on-wheels radar system was nearly flooded when between 4 and 14 inches of rain fell in various portions of the Quinault Valley, raising Lake Quinault by about six inches per hour over a period of several hours. For details, check out science summary for the day, which describes some of the measurements that were taken.
“We’re not just checking the satellite’s observations, the way you might double-check a simple distance measurement,” said project manager Lynn McMurdie in a news release from the University of Washington.
“We’re checking the connection between what the satellite sees from space, what’s happening in the middle of the storm system and what reaches the ground, which is what most people ultimately want to know,” McMurdle said. “So we’re not just improving the satellite’s performance — we’re learning how storm systems work.”
NASA’s “Precipitation Education” website explains how weather systems from the Pacific Ocean are experienced on land and how Olympex will sort things out:
“Large weather systems arrive in the Pacific Northwest from the ocean, and not all parts of the system are equal. The leading edge, called the pre-frontal sector, tends to be warmer and have steady rainfall. Next, the frontal sector marks the transition from the warmer air to the colder air and processes that produce rainfall are often most intense in this region. Finally the post-frontal sector, characterized by colder temperatures, will often bring showery rain and snow, and can produce large snowfall accumulations at higher elevations.
“The (Olympex) field campaign will be looking inside these storm clouds with ground radar and aircraft instruments to determine the accuracy of the GPM satellite constellation in detecting the unique precipitation characteristics in these different storm sectors.
“One of the aircraft will be flying through the clouds to make detailed measurements of raindrops, ice particles, and snowflakes as they are falling to Earth’s surface. Combined with data from the ground radars and the total amounts caught by the rain gauges and other instruments on the ground, scientists will be able to improve the computer models of precipitating clouds – the same types of computer models used to forecast the weather and project future climate.”
If you’d like to learn more about Olympex, check out these sources:
- UW news release
- NASA news release
- NASA’s brochure on GPM Core Observatory PDF 84.9 mb)
- NASA’s “Precipitation Measurement Missions” website
- Olympex Facebook page
- Olympex Twitter feed
- Associated Press story by Phuong Le
- Seattle Times story by Sandi Doughton
