Integrated Precipitation and Hydrology Experiment (IPHEx)

The Integrated Precipitation and Hydrology Experiment (IPHEx) is a ground validation field campaign that will take place in the southern Appalachian Mountains in the eastern United States from May 1 to June 15, 2014. IPHEx is co-led by NASA's Global Precipitation Measurement mission, with partners at Duke University and NOAA's Hydrometerological Testbed.

The field campaign has two primary goals. The first is to evaluate how well observations from precipitation-monitoring satellites, including the recently launched GPM Core Observatory, match up to the best estimate of the true precipitation measured at ground level and how that precipitation is distributed in clouds. The second is to use the collected precipitation data to evaluate models that describe and predict the hydrology of the region. These models are used for predicting how much water is available in rivers and aquifers, for resource management and for flood and landslide prediction in the Upper Tennessee, Catawba-Santee, Yadkin-Pee Dee and Savannah river basins.

A number of instruments in the region already measure rain from the ground, and this campaign will add more. In the Pigeon River basin on the North Carolina side of the Upper Tennessee watershed and the Catawba River Basin in North and South Carolina, rain gauges, stream gauges, instruments called disdrometers that measure drop size, soil moisture sensors, and other equipment will measure rainfall.

The NASA Polarimetric weather radar (NPOL) and the Dual-frequency, Dual-polarimetric, Doppler radar (D3R) will be located on a cattle ranch in southern Rutherford County, North Carolina just across the Carolinas' border and north of Spartanburg S.C., and the NOAA X-band polarimetric radar (NOXP)  will be located on a ridge above the Pigeon Basin. These radars will take measurements of the air column above the river basins. Other smaller radars throughout the study area will get radar coverage of the region that’s as good as possible, given the challenges of the mountainous terrain.

In addition to the ground measurements, NASA's ER-2 plane will fly above with instruments to simulate satellite measurements, and the University of North Dakota's Citation aircraft will fly inside storms to measure raindrops and precipitation particles inside clouds. Data from satellite overpasses will also be included.

Together all the data will be used to improve rainfall estimates from the GPM Core Observatory and other precipitation satellites.

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