TRMM at 15: The Reign of Rain

When it rains it pours, goes the saying, and for the last 15 years, the data on tropical rainfall have poured in. NASA's Tropical Rainfall Measuring Mission (TRMM) was launched on Nov. 27, 1997, and for the last decade and a half has enabled precipitation science that has had far reaching applications across the globe. Rain is one of the most important natural processes on Earth, and nowhere does it rain more than across the tropics. Orbiting at an angle to the equator that covers 35 degrees north to 35 degrees south of the equator, TRMM carries five instruments that collectively measure the intensity of rainfall, characteristics of the water vapor and clouds, and lightning associated with the rain events. One of the instruments, the Precipitation Radar, built by NASA's mission partner the Japan Aerospace Exploration Agency (JAXA), is the first precipitation radar flown in space. It returns images of storms that for the first time have revealed close up three-dimensional views of how rainbands in tropical cyclones develop, potentially indicating how strong the storms might become.