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The NPOL instrument, a large circular radar dish under a blue sky
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.

Credits
NASA