PRECIPITATION MEASUREMENT MISSIONS

The Japanese H-IIA
rocket will carry the GPM
Core Observatory into orbit
in 2014.
Source: JAXA

Core Observatory

Carrying both a dual frequency radar instrument and a a multi-channel microwave radiometer, the Core Spacecraft will provide a new reference standard for precipitation measurements from space.

The Core Spacecraft is being developed and tested in-house at NASA Goddard Space Flight Center.

A scientific spacecraft carries numerous instruments designed to measure specific phenomena. Scientists must control, very precisely, where each instrument on the spacecraft is pointing, so that data is collected from the intended targets. Not only do the instruments have to be moved from target to target, they must be held steady on a target long enough, as the spacecraft moves through space, to collect the needed data.

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GPM Instruments

GPM will be pointing toward Earth to measure precipitation. It will be vital to control the attitude (or physical orientation) of the Core Spacecraft accurately, so that we can map exactly where the resulting data originates on Earth. The Core observatory is uniquely instrumented with a conically-scanning radiometer and a cross-track scanning radar:

• GPM Microwave Imager (GMI)
• Dual-frequency Precipitation Radar (DPR)

The well calibrated GPM Microwave Imager (GMI) measurements and the well characterized scene obtained from the Dual-frequency Precipitation Radar (DPR) will combine to provide an excellent reference against which to calibrate other microwave radiometers in the GPM constellation when overlapping measurements of same Earth scene are made. The DPR will have the capability to make detailed three-dimensional measurements of cloud structure, rainfall, and rain rates. These detailed measurements will provide further understanding of the microwave radiometric measurements made by the GMI.