PRECIPITATION MEASUREMENT MISSIONS

Seeing Through the Clouds

Satellites allow us to observe changes in the precipitation structure over the life cycle of a storm, even over ocean and regions where conventional data are sparse. In particular, we now have insights into the dynamics of a storm, such as how the eye of a hurricane stays stable as the storm moves across the Earth’s surface, and how tropical cyclones intensify through the presence of “hot tower” structures.

TRMM image of Hurricane Bonnie displaying the eyewall and
hot tower structures.

A ‘mesoscale convective system’ is a grouping of thunderstorms ranging in size from a few to several hundred kilometers that can last for a few hours or more.  The rain that falls from these systems can lead to dangerous flooding with significant social and economic impacts. Predicting and monitoring these high-impact natural hazard events depends on accurate and timely knowledge of precipitation at local and regional scales.

TRMM was revolutionary in its ability to observe storms within the tropics. It currently provides important information about the structure and intensity of rain storms in the tropics. TRMM fills a significant gap in our observations and increases our knowledge about rainfall and our understanding of how energy, moving through the tropics and sub-tropics, impacts atmospheric circulation throughout the globe.

The Global Precipitation Measurement (GPM) mission will expand our observational capabilities beyond the tropics, tracking tropical storms as they move into the mid-latitudes and, for the first time, providing a three dimensional view of the storms’ structural changes as they move towards the poles. GPM’s improved tracking of the life-cycle of a storm will help us understand why some, but not all, storms change intensity as they transition from the tropics to the mid-latitudes.