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Earth Matters

A New Perspective on Precipitation

January 23rd, 2013 by mscott

In late 2012, floods swamped the United Kingdom and news reports said tens of thousands of residents had been affected. It was the kind of natural hazard the Earth Observatory tries to cover, but floods can be hard to see. When heavy rains are in progress, storm clouds typically hide the flooding from satellite sensors. Even if flooding lingers after the clouds clear away, certain types of land cover (such as dense forests) can make floods notoriously difficult to spot.

Another way of seeing floods caused by rainfall is to look at the rainfall itself. The Earth Observatory sometimes publishes imagery from the Multisatellite Precipitation Analysis (MPA). MPA estimates rainfall by combining measurements from multiple satellites and calibrating them using rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite.

But as its name implies, TRMM focuses on the tropics. More specifically, TRMM specializes in picturing moderate to heavy rainfall over the tropical and subtropical regions. So we can visualize rainfall at relatively low latitudes, but places like the United Kingdom are too far north for this approach to work well.

GPM satellite constellation. Courtesy NASA Precipitation Measurement Missions.

Fortunately a solution is on the horizon—or more accurately, set to launch next year. The Global Precipitation Measurement (GPM) mission is an international collaboration spearheaded by NASA and the Japan Aerospace Exploration Agency (JAXA). Scheduled to launch in June 2014, the GPM Core Observatory will improve upon TRMM by extending observations to higher latitudes. And GPM won’t just focus on heavy rain; it will also observe light rain and snow, which comprise a significant portion of the precipitation at higher latitudes.

The NASA overview of GPM explains:

GPM will provide global precipitation measurements with improved accuracy, coverage, and dynamic range for studying precipitation characteristics. GPM is also expected to improve weather and precipitation forecasts through assimilation of instantaneous precipitation information.

So although the EO can’t visualize heavy rains in places like the UK now, that situation should change after the launch of GPM.

One Response to “A New Perspective on Precipitation”

  1. Sue Newton says:

    I shall look forward to the new information as I live in the UK