Getting the Big Picture: Remote Sensing

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A brief animated look at the different types of remote sensing techniques that NASA uses to study the Earth. This video discusses why we need remote sensing to study the Earth, and the differences between active and passive remote sensing from satellites. It also gives examples of different types of data NASA satellites collect about the Earth, and some of the applications of that data.

This video is public domain and can be downloaded in high resolution here.


Updated GPM Radiometer Products

The Precipitation Processing System (PPS) has begun producing updated GPM radiometer products as of 12/4/2014 due to an error discovered in the calculation of the Sun Angle in the PPS Geolocation Toolkit. This is considered a minor update with the Product Version being incremented in letter only. Please see the list of affected products here: 

GPM Combined Radar-Radiometer Precipitation Algorithm Theoretical Basis Document (ATBD) (Version 03)

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The GPM Combined Radar-Radiometer Algorithm performs two basic functions: first, it provides, in principle, the most accurate, high resolution estimates of surface rainfall rate and precipitation vertical precipitation distributions that can be achieved from a spaceborne platform, and it is therefore valuable for applications where information regarding instantaneous storm structure are vital.

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Radiometer Algorithms

Precipitation radiometers provide additional degrees of freedom for interpreting rain and snow in clouds through the use of multiple passive frequencies (9 for TRMM and 13 for GPM). Brightness temperatures at each frequency are a measure of everything in their field of view. These frequencies from the low (10 GHz) end to the high (183 GHz) end transition from being sensitive to liquid rain drops to being sensitive to the snow and ice particles.

Combined Radar Radiometer Algorithms

The combined use of coincident active and passive microwave sensor data provides complementary information about the macro and microphysical processes of precipitating clouds which can be used to reduce uncertainties in combined radar/radiometer retrieval algorithms. In simple terms, the combined algorithms use the radiometer signal as a constraint on the attenuation seen by the radar.

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