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Ground Validation

Content related to ground validation activities and field campaigns.

NPOL Ground Validation Instrument

The NPOL instrument, a large circular radar dish under a blue sky
Image Caption
The NASA NPOL radar is a research grade S-band, scanning dual-polarimetric radar.

The NPOL underwent a complete antenna system upgrade in 2010 and is one of two fully transportable research-grade S-band systems in the world.  It is used to make accurate volumetric measurements of precipitation including rainfall rate, particle size distributions, water contents and precipitation type.

NPOL

GPM flying over Earth with a data swath visualized.
Monday, June 27, 2011
The NASA NPOL radar is a research grade S-band, scanning dual-polarimetric radar. The NPOL underwent a complete antenna system upgrade in 2010 and is one of two fully transportable research-grade S-band systems in the world. It is used to make accurate volumetric measurements of precipitation including rainfall rate, particle size distributions, water contents and precipitation type. Click here to view the latest NPOL data from the GPM Precipitation Science Research Facility at Wallops Flight Facility. Examples of NPOL-Generated Images
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Ground and Airborne Instruments

The NPOL instrument, a large radar dish attached to a trailer under a blue sky
Monday, June 27, 2011
To gain a better understanding of precipitation processes and to assess and refine the physical assumptions that go into the GPM algorithms, the ground validation team makes field measurements of specific parameters that describe the physical characteristics and variability of rainfall, including rainfall intensity, distribution, particle shape and precipitation type. Ground validation uses specific ground instrumentation infrastructure developed to observe, quantify and document the physical properties of precipitation. These instruments include: The NASA NPOL radar A research grade S-band...
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Integrated Hydrological Validation

GPM flying over Earth with a data swath visualized.
Monday, June 27, 2011
Integrated hydrologic validation assesses GPM precipitation products by considering how the accuracy of rainfall products being input into hydrological and land-surface modeling affects model outputs. The end goals are to evaluate satellite precipitation measurements for their impacts and utility, and to provide guidance to algorithms that turn satellite retrievals into meaningful estimates of precipitation. The integrated hydrologic modeling process provides a vehicle to evaluate precipitation inputs over a given hydrological basin (watershed) where the surface inputs (land cover, soil type)...
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Physical Validation

GPM flying over Earth with a data swath visualized.
Monday, June 27, 2011
Physical validation activities collect targeted datasets that describe precipitation physics: the size, type, shape and number of raindrops throughout the air column from the cloud to the ground. Scientists use ground validation measurements to evaluate specific assumptions or hypotheses related to the physical behavior of precipitation, and the manner in which those characteristics are, or are not, well represented in a given retrieval algorithm. The goal of this validation process is to improve and fully develop physically-based precipitation retrieval algorithms. These algorithms are the...
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