https://phys.org/news/2018-09-nasa-rainfall-analysis-super-typhoon.html

The NASA rainfall accumulation analysis was derived from NASA's Integrated Multi-satellitE Retrievals for GPM data (IMERG). GPM is the Global Precipitation Measurement mission satellite, managed by both NASA and the Japan Aerospace Exploration Agency.

IMERG data are used to calculate estimates of precipitation from a combination of space-borne passive microwave sensors, including the GMI microwave sensor onboard the GPM satellite, and geostationary IR (infrared) data. The analysis showed IMERG rainfall estimates over the western Pacific Ocean during the period from September 11-17, 2018. During that period typhoon Mangkhut moved west of Guam to the Philippines and then over the South China Sea into southeastern China. Rainfall totals above 300 mm (11.8 inches) were often indicated along Mangkhut's path. The highest rainfall accumulation estimates of over 700 mm (27.6 inches) were shown by IMERG south of Mangkhut's track in the Philippine Sea.