LEAD: If you want to test and fine-tune a satellite that measures snow and rain, it makes sense to go to THE wettest area in the United States: the rainforest of Washington State.
1. Each year the slopes of the Olympic Mountains are soaked with over 100 inches of rain, with a record total of 184", or 15 feet of rain!
2. NASA and university scientists are utilizing NASA's DC-8 and ER-2 research planes as well as ground radar and other instruments to gather "ground truth" data to help calibrate NASA’s Global Precipitation Measurement (GPM) satellite, launched in 2014.
TAG: The GPM satellite network of 12 satellites provides unprecedented worldwide radar measurements of precipitation every 30 minutes that will assist weather and climate scientists, as well as flood emergency managers.