PRECIPITATION MEASUREMENT MISSIONS

In late April, 2011, warm winds from the Gulf of Mexico met cold air from Canada in a giant storm system that covered a large portion of the central and southeastern United States. The region was hit by an onslaught of tornadoes, making it the largest outbreak since 1974. According to the National Weather Service, 178 confirmed tornadoes were reported on April 25-28, including three rare EF-5 storms strong enough to collapse a concrete building, which hit Smithville, Mississippi, Hackleberg and Phil Cambell, Alabama, and Philadelphia, Missouri. The three day outbreak caused immense destruction across the southeast and killed 321 people.

Tornado funnel in central Oklahoma.

The dust had barely settled when a second major tornado outbreak occurred one month later. On May 22, 2011, another EF-5 tornado flattened Joplin, Missouri, killing 141 people and injuring hundreds of others, making it the 8th deadliest tornado in U.S. History, according to the National Weather Service. The tornado had wind speeds over 200 mph and a destructive track six miles long.

The TRMM satellite saw the severe weather unfold over the United States during both the April outbreak and the Joplin tornado in May. TRMM Microwave Imager (TMI) and Precipitation Radar (PR) data from April 27 shows numerous intense thunderstorms stretching from Louisiana to the Ohio valley. On May 22, two hours before the tornado touched down in Joplin, TRMM recorded a rotating thunderstorm with heavy rains. (Source)

By the end of May 2011, over 1300 tornadoes had occurred, more than the yearly average of the past ten years. April alone had a record breaking 875 tornado touchdowns.

TRMM TMI and PR observe rainfall accumulation over the storm and 3-D vertical structure in a section of this line of storms on April 27th, 2011.

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Numerical Weather Prediction

Numerical weather prediction (NWP) is the use of computer models to predict upcoming weather.  TRMM and GPM provide more accurate and frequent observations of rainfall in near real-time which helps numerical weather prediction centers around the world, including the European Centre for Medium-Range Weather Forecasts (ECMWF), the Japan Meteorological Agency (JMA), and the National Center for Environmental Prediction (NCEP) improve the global and regional models they use to forecast weather.  NWP centers are are currently incorporating or plan to incorporate microwave-based satellite rainfall information, which studies show can improve forecasts of extreme weather such as hurricanes.  Methods for integrating rainfall data are constantly evolving, and with more data available in the coming decade from GPM, scientists expect to see even more improvements. In addition, many NWP agencies are now creating precipitation products for “nowcasting” weather in the immediate 6 hours to meet the needs of a wider user community, including weather forecasters, hydrologists, farmers, numerical modelers, the military and the climate community.

Winter Weather

An exceptionally severe winter storm dropped several feet of snow around the Washington, D.C. area in early February 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this true-color image on February 7, 2010, showing part of the region affected by heavy snowfall.

Credit: NASA Earth Observatory

In 2010 to 2011, blizzards and intense snowfall caused tens of thousands of canceled flights and even more blocked roads and traffic accidents across the U.S. East coast and Western Europe. While these winter storms demonstrate the impact of extreme weather, only a few current space-borne instruments can measure falling snow by exploiting sensors with unique frequency channels designed to measure water vapor. The GMI and DPR instruments onboard the GPM Core Observatory are the first space-borne sensors specifically designed to detect falling snow from space. Through several pre-launch field testing campaigns, scientists are working with ground, aircraft, and satellite instrumentation to match observations on the ground with instrument observations so they can develop methods to measure falling snow using the GPM Core satellite instruments.