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- [Source: NASA CloudSat home page]
The Cloud Profiling Radar (CPR) is a 94-GHz nadir-looking radar which measures the power backscattered by clouds as a function of distance from the radar. The CPR was developed jointly by NASA/JPL and the Canadian Space Agency (CSA). The overall design of the CPR is simple, well understood, and has strong heritage from many cloud radars already in operation in ground-based and airborne applications. Most of the design parameters and subsystem configurations are nearly identical to those for the Airborne Cloud Radar, which has been flying on the NASA DC-8 aircraft since 1998.
The design of the CPR is driven by the science objectives. The original requirements on CPR were: sensitivity defined by a minimum detectable reflectivity factor of -30 dBZ, along-track sampling of 2 km, a dynamic range of 70 dB, 500 m vertical resolution and calibration accuracy of 1.5 dB. The minimum detectable reflectivity factor requirement was reduced to -26 dBZ when the mission was changed to put CloudSat into a higher orbit for formation flying.
To achieve sufficient cloud detection sensitivity, a relatively low frequency (i.e. <94 GHz) radar would require an enormous antenna and high peak power. At frequencies much greater than 100 GHz, a large antenna and high peak power are also needed due to rapid signal attenuation through cloud absorption. Furthermore, technologies at such high frequencies are less well developed. The 94-GHz frequency chosen by CPR offers the best compromise, meeting performance within the spacecraft resources. In fact, most existing airborne cloud radars operate at 94 GHz. These airborne radars provide extensive heritage for CPR on instrument design and technology, data processing, and retrieval algorithms. A primary frequency allocation of 94 GHz for spaceborne cloud radar sensing has been formally approved at the 1997 World Radio Conference.
Group: Instrument_Details
Entry_ID: CLOUDSAT-CPR
Group: Instrument_Identification
Instrument_Category: Earth Remote Sensing Instruments
Instrument_Class: Active Remote Sensing
Instrument_Type: Spectrometers/Radiometers
Instrument_Subtype: Radar Spectrometers
Short_Name: CLOUDSAT-CPR
Long_Name: CLOUDSAT CLOUD PROFILING RADAR
End_Group
Group: Associated_Platforms
Short_Name: CLOUDSAT
End_Group
Group: Spectral_Frequency_Information
Wavelength_Keyword: RADIO
Spectral_Frequency_Coverage_Range: 94 GHz
End_Group
Online_Resource: http://cloudsat.atmos.colostate.edu/instrument
Sample_Image: http://www.sti.nasa.gov/tto/Spinoff2006/images/p110-125_img_8.jpg
Creation_Date: 2007-05-22
Group: Instrument_Logistics
Data_Rate: 15 kbps
Instrument_Owner: USA/NASA
End_Group
End_Group
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