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Celebrating the Upcoming Launch of Global Precipitation Measurement (GPM) Mission

Thomas Harris

Over the last decades, nations around the world have built sophisticated observation systems that can monitor changes to the earth system with high confidence and precision. For example, NASA's EarthObserving System (http://eospso.gsfc.nasa.gov/) is a coordinated series of satellites that monitor long-term global observations of the land surface, biosphere, solid Earth, atmosphere, and oceans, and provides humanity with the baseline observations that permits monitoring of the global climate system.

But as powerful as our observation capability is, there are many unanswered questions related to climate change and the impacts of a warming world across the Earth system. Take for example global precipitation. With a warming global climate, how has global precipitation changed over the last decades? How are local changes in precipitation tied to the larger global climate system? How will precipitation change in the future? How will changes in precipitation affect human society? 

To monitor global precipitation, and to help answer these big questions, NASA is working with the Japan Aerospace Exploration Agency (JAXA) to launch a new satellite for monitoring global precipitation, Global Precipitation Measurement (GPM). GPM is an international satellite mission that will provide next-generation observations of rain and snow worldwide every three hours and will be the 'core' observatory for linking precipitation-related observations from a constellation of current and planned satellites to produce next-generation global measurements of rainfall and snowfall from space.

GPM, to be launched on the from the Tanegashima Space Centre, Tanegashima Island, Japan, on February 27, will extend the capability to acquire detailed, near real-time measurements of rain and snowfall on a global scale. One of the most exciting capabilities will be mapping the interior structure of storms in 3 dimensions, extending the capabilities of existing aging satellite systems like Tropical Rainfall Measurement Mission (TRMM).

For example, the TRMM imaging radar has 5 km (3.1 mile) horizontal resolution and 250 meter (820 foot) vertical resolution, which can clearly resolve the structure within storm clouds that contains raindrops and ice large enough to fall as precipitation. The image (above) was acquired by TRMM of Typhoon Bopha as it moved toward Mindanao, the second largest major island in the Philippines, in December of 2012, and reveals details like a double eyewall, two concentric rings of intense storm cells that reach 12 km in altitude. The Dual-frequency Precipitation Radar (DPR) launching with GPM, is expected to be more sensitive than its TRMM predecessor, especially in the measurement of light rainfall and snowfall.  

Apart from the impressive capabilities for observing individual precipitation events, a huge benefit from GPM will be in extending the 15-year precipitation record created by TRMM and helping answer some of the big questions around the Earth system and humanity's impact on global climate.

Thanks to Owen Kelley at NASA GSFC (owen dot kelley at nasa dot gov) for the image of Bopha.

 

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