NASA' s TRMM Satellite Measured Philippines' Extreme Tropical Cyclone Rainfall In 2009
Tropical cyclones passing over or near the northern Philippines caused many severe floods, landslides and numerous lost lives during the 2009 western north Pacific typhoon season. Tropical cyclones can form year around in this area but most occur between May and November. The Tropical Rainfall Measuring Mission or TRMM satellite, managed by both NASA and the Japanese Space Agency, JAXA has the ability to measure tropical rainfall from space, and confirmed this year's extreme rainfall in the Philippines.
The Philippines is hit by an average of 6-7 tropical cyclones every year but this season was above average when at least 11 named tropical cyclones traveled close enough to add to the Philippines' yearly rainfall totals. Over 20% of the rainfall in the northern Philippines normally comes from tropical cyclones.
An area just northeast of the Philippines, where typhoons frequently rapidly intensify, has the highest percentage (30%) of rainfall from tropical cyclones in the northwestern Pacific Ocean. Those rainfall data used in this analysis were from merged satellite rainfall estimates whose accuracy was calibrated with TRMM satellite data.
The heaviest rainfall contributed by tropical cyclones was over 1400 mm (55 inches) in the area traversed by deadly Typhoon Parma. Parma made a zig-zag rampage over the northern Philippines from October 14-27. In addition to Parma, other tropical cyclones added over 400 mm (15 inches) of rain to most of the northern Philippines.
Hal Pierce, SSAI/NASA Goddard Space Flight Center