Ground Validation Documents

  • Validation Network Data Product User’s Guide - Volume 2 (GPM)
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    Publication Date:
    11/16/2015
    Abstract / Summary:

    This document provides a basic set of documentation for the data products available from the GPM Ground Validation System (GVS) Validation Network (VN). In the GPM era the VN performs a direct match-up of GPM’s space-based Dual-frequency Precipitation Radar (DPR) data with ground radar data from the U.S. network of NOAA Weather Surveillance Radar-1988 Doppler (WSR-88D, or “NEXRAD”). Ground radar networks from international partners are also part of the VN. The VN match-up will help evaluate the reflectance attenuation correction algorithms of the DPR and will identify biases between ground observations and satellite retrievals as they occur in different meteorological regimes. Volume 2 of the Validation Network Data User’s Guide describes the GPM core and constellation VN data set. 

    An earlier version  of the VN capability performed a match-up of Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) data with ground-based radar (GR) measurements from a subset of the WSR-88D sites now included in the GPM-era VN operational radar data network. Legacy TRMM data and their matching GR observations will continue to be part of the VN operations in the GPM era.  Refer to Volume 1 of the Validation Network Data User’s Guide for a description of the legacy TRMM-specific VN data set.

     

  • MC3E Summary from The Earth Observer, January 2012
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    Publication Date:
    02/01/2012
    Abstract / Summary:

    This excerpt from the NASA Earth Observer publication provides and in-depth summary of the Midlatitude Continental Convective Clouds Experiment (MC3E), which took place from April 22nd - June 6th 2011 in central Oklahoma. The overarching goals of the field effort were to provide a complete three-dimensional characterization of precipitation microphysics in the context of improving the reliability of GPM precipitation retrievals over land, and to advance understanding of the primary physical components that form the basis for models that simulate convection and clouds.

  • GCPEX Science Plan
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    Publication Date:
    09/02/2011
    Abstract / Summary:

    During the GPM pre-launch period physically-based snowfall retrieval algorithms are in an active phase of development. Further refinement and testing of these emerging algorithms requires the collection of targeted ground-validation datasets in snowing environments. This document describes a field campaign effort designed to provide both new datasets and physical insights related to the snowfall process- especially as they relate to the incorporation of appropriate physics into GPM snowfall retrieval algorithms. The referenced field campaign effort is the GPM Cold Season Precipitation Experiment (GCPEx), a collaboration between the NASA GPM Ground Validation (GV) program and its international partner Environment Canada (EC).

  • International Ground Validation Research Programme of GPM: Report of 1st International GPM GV Requirements Workshop
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    Report of the 1st International GPM GV Requirements Workshop.

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    2DVD at Egbert, CARE, Canada
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    Presentation of CSU's 2-Dimensional Video Disdrometer for the Canadian CloudSat/CALIPSO Validation Programme

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    A GPM-DOE Midlatitude Continental Convective Clouds Experiment (MC3E)
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    To improve the fidelity of radiometer-based rainfall estimates over land at short temporal and spatial scales, the Global Precipitation Measurement mission (GPM) requires development of physically-based passive microwave (PMW) precipitation retrieval algorithms anchored by dual-frequency precipitation radar (DPR) drop size distribution (DSD), hydrometeor profile and rain rate retrievals. Emphasizing this need, the 2nd GPM Ground Validation White Paper (Kummerow and Petersen, 2006; hereafter GVWP) outlined the many significant challenges involved with the development and validation of these algorithms. To broadly paraphrase the GVWP, PMW algorithm development/validation over land requires not only an improved understanding of cloud and precipitation microphysics (particularly in the ice and mixed phases), but an improved representation of microphysical processes/properties (at the bulk and particle scales) in relevant cloud and/or empirical models- to include improved formulation of the radiative transfer occurring in a variable background of land-surface emissivity. Considering that 1) precipitation estimates made by the GPM satellite constellation will rely most heavily on PMW and combined DPR/PMW retrieval algorithms; 2) there are currently no robust physically-based PMW precipitation retrieval algorithms available for use over land1; and 3) GPM objectives ascribe considerable importance to making accurate measurements over land where people live, water resources are managed, and flooding occurs; the ability to accurately retrieve precipitation over land using combined DPR/PMW and or PMW-only algorithms, especially those areas not covered by radar and/or rain gauge networks, is critical to the overall success of GPM. The proposed GPM GV effort thus devotes significant effort and resources to improving the basic understanding required for developing and validating physically based PMW algorithms over land.

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    2-Dimensional Video Disdrometer (2DVD) from IOP-2
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    A series of measurements at the CARE site from the 2DVD instrument.

  • Snowflake Size Distribution Measurements in South Central Ontario, Canada
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    Parsivel Distrometer Results presented at the American Geophysical Union, Spring 2007.

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    C3VP 2007 IOP3 Case Summary
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    n all, 9 snowfall events were observed during IOP-3. All of these events were observed by the King City radars, 8 of the events were observed by the University of Massachusetts 3-frequency (W-, Ka, and Ku-band) Advanced Multi-Frequency Radar (AMFR), and 3 of the events were also observed with Convar-580 overflights.

    This document is a case summary of the dates, times, snowfall types, and instruments used during these 9 IOP-3 snowfall events.

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    Snowflake Video Imager at C3VP
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    The NASA Snowflake Video Imager obtained nearly continuous data from 1 Dec 06 thru 7 Mar 07.

    This presentation contains a summary for the entire data set, which is sorted into (a) priority days selected by GSFC investigators, and (b) non-priority days.

    The results are displayed in images of DSD(t), which reveal (a) the large variability of snowflakes sizes during events and (b) the intermittency of snowfall – even during intense storms.

    Additionally, results from a preliminary study of snowflake orientation reveals that there is a higher occurrence of snowflakes that are ‘horizontally’ orientated than ‘vertically’ orientated.

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