Latest Documents

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    Annex K: Canadian CloudSat/CALIPSO Validation Project (C3VP) Data Protocol
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    Protocol for C3VP data.

  • Prototype of NASA’s Global Precipitation Measurement Mission Ground Validation System
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    Abstract:

    NASA is developing a Ground Validation System (GVS) as one of its contributions to the Global Precipitation Mission (GPM). The GPM GVS provides an independent means for evaluation, diagnosis, and ultimately improvement of GPM spaceborne measurements and precipitation products. NASA’s GPM GVS consists of three elements: field campaigns/physical validation, direct network validation, and modeling and simulation. The GVS prototype of direct network validation compares Tropical Rainfall Measuring Mission (TRMM) satellite-borne radar data to similar measurements from the U.S. national network of operational weather radars. A prototype field campaign has also been conducted; modeling and simulation prototypes are under consideration.

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    A Global Precipitation Mission (GPM) Validation Network Prototype
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    A Validation Network (VN) prototype is currently underway that compares data from the Tropical Rainfall Measuring Mission (TRMM) satellite Precipitation Radar (PR) to similar measurements from the U.S. national network of operational weather radars. This prototype is being conducted as part of the ground validation activities of the Global Precipitation Measurement (GPM) mission. The purpose of the VN is to provide a means for the precipitation community to identify and resolve significant discrepancies between the U.S. national network of ground radar observations and satellite observations. The ultimate goal of such comparisons is to understand and resolve the first order variability and bias of precipitation retrievals in different meteorological/hydrological regimes at large scales. The VN prototype is based on research results and computer code described by Anagnostou et al. (2001), Bolen and Chandrasekar (2000), and Liao et al. (2001).

  • Light Precipitation Validation Experiment (LPVEx) Science Plan
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    The Light Precipitation Evaluation Experiment (LPVEx) planned for the Gulf of Finland in September and October, 2010 will seek to address this shortcoming by collecting microphysical properties, associated remote sensing observations, and coordinated model simulations of high latitude precipitation systems to drive the evaluation and development of precipitation algorithms for current and future satellite platforms. Specifically, LPVEx seeks to characterize the ability of CloudSat, the Global Precipitation Measurement mission (GPM) Dual-frequency Precipitation Radar (DPR), and existing/planned passive microwave (PMW) sensors such as the GPM microwave imager (GMI) to detect light rain and evaluate their estimates of rainfall intensity in high latitude, shallow freezing level environments. Through the collection of additional microphysical and environmental parameters, the campaign will also seek to better understand the process of light rainfall formation and augment the currently limited database of light rainfall microphysical properties that form the critical assumptions at the root of satellite retrieval algorithms. Specific science questions include: identify source of spread in current satellite estimates of rainfall- minimum detectable rain rates, phase discrimination, physical assumptions in algorithms, spatial variability,

    • What are the minimum rainrates that can be detected by current satellite precipitation sensors in environments with shallow freezing levels (lower than 2 km)?
    • How will rainfall detection be improved by proposed future platforms?
    • How well can these sensors discriminate rain from falling snow?
    • Are the microphysical assumptions, such as raindrop size distribution, cloud water contents, and properties of the melting layer and precipitating ice aloft, currently employed in global satellite precipitation algorithms representative of high latitude precipitation in a statistical sense?
    • What is the impact of variability in these microphysical assumptions and those related to vertical structure and spatial inhomogeneity on random errors in retrieved rainfall rate?
    • Collectively, are the above inter-sensor differences large enough to explain the wide spread in current satellite estimates of high-latitude rainfall?
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    C3VP Access Information
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    A summary of C3VP data access.

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    Disdrometer Derived Z-S Relations in South Central Ontario, Canada
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    During the winter of 2006-2007, a number of in-situ and remote sensing precipitation measuring devices were operated at the Center of Atmospheric Research Experiment (CARE) site located near Egbert, Ontario about 30 km to the NW of the King City C-band operational dual-polarized radar. While the experiment was originally designed to measure winter precipitation for the Canadian Cloudsat/CALIPSO validation program (C3VP), the NASA’s Global Precipitation Measurement (GPM) ground validation program joined the efforts (cf. Petersen et al., 2007; this conference) bringing optical disdrometers (2D-video and two Parsivel disdrometers) and a multi-frequency radar. The CARE is a well- instrumented facility including Vaisala FD12P visibility sensor, Precipitation Occurrence Sensor System (POSS), the McGill University’s vertically-pointing X- band Doppler, and Hydrometeor Velocity and Shape Detector (HVSD).

    In this paper we focus on two case studies, (a) the 6 December 2006 and (b) the 22 January 2007 snow events. Our objectives are six-fold, (a) to determine the characteriscs of snow size spectra, (b) to determine the bulk density of snow by comparing measurements of Parsivel and FD12P, (c) to estimate a density (ρ) versus ‘size’ relation for snow by comparing the 2D-video derived Zh measurements with the well-calibrated King City Zh data, (d) to compare the Zh between 2D-video, POSS and King City radars, (e) to estimate snowfall rate (SR) and equivalent melt water (MWR) rate, including comparison of melt water accumulations from 2D-video, POSS, and other ground-based instruments at the CARE site, and (f) to derive the Zh-SR and Zh-MWR power law relations from 2D-video and Parsivel data.

     

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    Profiler Data Sets for the NASA PMM Community
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    In support of NASA PMM, observations collected near Darwin, Australia, have been processed and data sets are being provided to the NASA PMM community to help validate and improved satellite retrieval algorithms and cloud resolving models.

    The data sets are derived from surface rain gauges, a disdrometer, and vertical pointing profilers deployed at the Australian Bureau of Meteorology Research Centre (BMRC) wind profiler site near Darwin, Australia during the Tropical Western Pacific – International Cloud Experiment (TWP-ICE).

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    Realization of the NASA Dual-Frequency Dual-Polarized Doppler Radar (D3R)
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    ABSTRACT:

    This paper describes some of the novel technologies adopted in the realization of the NASA Dual-frequency Dual- polarized Doppler Radar (D3R) system for to be used by the GPM ground validation program. A description of the transceivers and major trades that lead to a solid-state architecture is presented. Other aspects enabling the design such as the waveform design and generation and the digital receiver is also described. Data measured from a similar power amplifier was used to estimate the expected range side lobe performance. An estimate of the expected sensitivity based on the transceiver parameters also presented.

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    GPM Ground Validation System Level 3 Requirements for a Mobile Ka-/Ku-band Radar
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    Background and Purpose:
    This specification defines the Level 3, system-level functional and performance requirements for NASA’s Global Precipitation Measurement (GPM) mission Ground Validation System Mobile Radar (GVSMR).

    Document Scope:
    This document sets forth requirements for NASA’s GPM GVSMR including necessary ground validation measurement, data ingest, processing, archiving, and distribution.
    The structure and functional breakdown of this document are used to organize the requirements only, and should not be interpreted as a physical architecture or allocation. Physical attributes and implementation approaches of the GVSMR are intentionally omitted from this document.
    The GVS requirements presented in this document are traceable to the NASA GPM Level 2 Requirements.

  • Download File:
    D3R Technical Specifications
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    Detailed specifications document for the Dual-Frequency, Dual-Polar, Doppler Radar (D3R)

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