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GPM Ground Validation Two-Dimensional Video
Disdrometer (2DVD) Table of Contents Important Notice Concerning LPVEX Data Between September 15-22, 2010, the 2DVD data sets collected at Emasalo (SN36) and Harmaja (SN37) are +2 hours offset from UTC, and the 2DVD data set collected at Jarvenpaa (SN35) is +3 hours offset from UTC. The time stamps in these data files will be corrected and re-posted to this archive by mid September 2012. A disdrometer is an instrument that measures the size of rain drops. The Two-Dimensional Video Disdrometer (2DVD), developed by Joanneum Research (Graz, Austria), is unique in that it records two side view optical images of each raindrop. Used for in situ measurements of precipitation drop size distribution, this instrument records orthogonal image projections of raindrops as they cross its sensing area and can provide a wealth of information, including velocity and shape of individual raindrops. An interesting article showing how the 2DVD can be used to analyze the microstructure of individual raindrops can be found here. This disdrometer data set gathers data during field experiments for the Global Precipitation Measurement (GPM) mission Ground Validation campaign. CitationThe following examples show how to cite the use of these data sets in a publication. For more information, please see our Citing GHRC DAAC and Data page. Peterson, W., L. Carey, V.N. Bringi, A. Tokay, and P. Gatlin. 2010. GPM Ground Validation Two-Dimensional Video Disdrometer (2DVD) LPVEx [indicate subset used]. Data set available online [http://ghrc.nsstc.nasa.gov/] from the NASA EOSDIS Global Hydrology Resource Center Distributed Active Archive Center Huntsville, Alabama, U.S.A. doi: [Coming Soon] Peterson, W., L. Carey, V.N. Bringi, A. Tokay, and P. Gatlin. 2011. GPM Ground Validation Two-Dimensional Video Disdrometer (2DVD) MC3E [indicate subset used]. Data set available online [http://ghrc.nsstc.nasa.gov/] from the NASA EOSDIS Global Hydrology Resource Center Distributed Active Archive Center Huntsville, Alabama, U.S.A. doi: http://dx.doi.org/10.5067/GPMGV/MC3E/2DVD/DATA301 Peterson, W., A. Tokay, and P. Gatlin. 2012. GPM Ground Validation Two-Dimensional Video Disdrometer (2DVD) GCPEx [indicate subset used]. Data set available online [http://ghrc.nsstc.nasa.gov/] from the NASA EOSDIS Global Hydrology Resource Center Distributed Active Archive Center Huntsville, Alabama, U.S.A. doi: 10.5067/GPMGV/GCPEX/2DVD/DATA101 Peterson, W. and P. Gatlin. 2013. GPM Ground Validation Two-Dimensional Video Disdrometer (2DVD) IFloodS [indicate subset used]. Data set available online [http://ghrc.nsstc.nasa.gov/] from the NASA EOSDIS Global Hydrology Resource Center Distributed Active Archive Center Huntsville, Alabama, U.S.A. doi: http://dx.doi.org/10.5067/GPMGV/IFLOODS/2DVD/DATA301 CampaignsThe Global Precipitation Measurement (GPM) mission Ground Validation (GV) campaign will use a variety of methods for validation of GPM satellite constellation measurements prior to launch of the GPM Core Satellite, which is currently scheduled for July 2013. The validation effort will entail numerous GPM-specific and joint-agency/international external field campaigns, using state of the art cloud and precipitation observational infrastructure (polarimetric radars, profilers, rain gauges, disdrometers). Surface rainfall will be measured by very dense rain gauge and disdrometer networks at various field campaign sites. These field campaigns will account for the majority of the effort and resources expended by Global Precipitation Measurement (GPM) mission Ground Validation (GV). The Light Precipitation Evaluation Experiment (LPVEx) took
place in September and October 2010 in the Gulf of Finland to characterize
the ability of CloudSat, the Global Precipitation 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. The experiment leveraged in
situ microphysical property measurements, coordinated remote sensing
observations, and cloud resolving model simulations of high latitude
precipitation systems to conduct a comprehensive evaluation of
precipitation algorithms for current and future satellite platforms. The
campaign will use these measurements to better understand the process of
light rainfall formation at high latitudes and augment the currently
limited database of light rainfall microphysical properties that form the
critical assumptions at the root of satellite retrieval algorithm. The 2DVD
data files provide both binary preprocessed hydrometer files created by
the instrument manufacturer's software as well as ASCII files containing
rain The 2DVD instruments were located at 3 sites in Finland: Harmaja, Emasalo, and Jarvenpaa. The serial numbers and site locations of the instruments are:
Information concerning coordinates and related instrumentation can be found in the LPVEX_Dataset_summary PDF document. The >Midlatitude Continental Convective Clouds Experiment
(MC3E) took place in central Oklahoma during the April-June 2011 period.
The experiment was a collaborative effort between the U.S. Department of
Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research
Facility and the National Aeronautics and Space Administration's (NASA)
Global Precipitation Measurement (GPM) mission Ground Validation (GV)
program. The field campaign leveraged the unprecedented observing
infrastructure currently available in the central United States, combined
with an extensive sounding array, remote sensing and in situ aircraft
observations, NASA GPM ground validation remote sensors, and new ARM
instrumentation purchased with American Recovery and Reinvestment Act
funding. The over arching goal was to provide the most complete
characterization of convective cloud systems, precipitation, and the
environment that has ever been obtained, providing constraints for model
cumulus parameterization and space-based rainfall retrieval algorithms
over land that had nee MC3E Further details on GPM MC3E are available at http://gpm.nsstc.nasa.gov/mc3e/. Information on MC3E ARM is available at http://campaign.arm.gov/mc3e/. The 2DVD instruments were located at 5 sites in Oklahoma. The serial numbers and site locations of the instruments are:
The GPM Cold-season Precipitation Experiment (GCPEx)
occurred in Ontario, Canada during the winter season of 2011-2012.
GCPEx addressed shortcomings in the GPM snowfall retrieval algorithm by
collecting microphysical properties, associated remote sensing
observations, and coordinated model simulations of precipitating snow.
These data sets were collected to aid in the achievement of the over
arching goal of GCPEx which is to characterize the ability of
multi-frequency active and passive microwave sensors to detect and
estimate falling snow.
Data was collected from October 27, 2011 to February 27, 2012. Further details on GCPEx are available at http://gpm.nsstc.nasa.gov/gcpex. The Iowa Flood Studies (IFloodS) was a ground measurement campaign that took place in eastern Iowa from May 1 to June 15, 2013. The goals of the campaign were to collect detailed measurements of precipitation at the Earth's surface using ground instruments and advanced weather radars and, simultaneously, collect data from satellites passing overhead. The ground instruments characterized precipitation -- the size and shape of raindrops, the physics of ice and liquid particles throughout the cloud and below as it falls, temperature, air moisture, and distribution of different size droplets -- to improve rainfall estimates from the satellites, and in particular the algorithms that interpret raw data for the upcoming Global Precipitation Measurement (GPM) mission's Core Observatory satellite, which launches in 2014. The 2DVD instruments were located at 6 sites in Iowa. The serial numbers and site locations of the instruments are::
Further details on the IFloodS campaign are available at http://gpm.nsstc.nasa.gov/ifloods. Additional information about the Iowa Flood Center can be found at http://iowafloodcenter.org. Information on the Global Precipitation Measurement (GPM) mission is available at http://pmm.nasa.gov/GPM. The Two-Dimensional Video Disdrometer (2DVD) uses two high speed line scan cameras which provide continuous measurements of size distribution, shape and fall velocities of all precipitation particles and types. Two orthogonal light planes, provided by two internal lamps, transect the approximate 10x10 cm virtual measurement area and are projected onto two high speed line-scan cameras. Precipitation particles (hydrometeors) that fall through the light planes cast a shadow that is recorded by the two cameras nested within the instrument (this is analogous to flat-bed scanners, except here the scan head is stationary and the scanned object moves). Detailed shape and size information for each individual hydrometeor is available via the two "side image shadows" that are recorded by the cameras. The light planes are separated by a precisely calibrated distance (nominally 6 mm) from which the vertical fall velocity can be measured. The line scan cameras sample each plane at a rate of ~18 microseconds and a horizontal resolution of ~200 microns. Therefore, as a raindrop falls through the measurement area, several line scans of each image are recorded from two sides and two different heights, from which precise measurements can be made. Data ProducersWalter A. Petersen V.N. Bringi Larry Carey Patrick Gatlin Ali Tokay The LPVEx data files are archived in a daily tar format with the following naming convention:
where,
The following files are contained within the tar archive:
The MC3E data files are archived in a daily tar format with the following naming convention:
where,
The following ASCII files are contained within the tar archive:
The 2DVD data files are archived in a daily tar format with the following naming convention:
where,
The tar files consist of binary and ASCII files containing information on each raindrop and snowflake sampled by both cameras. The following files are contained within the tar archive and follow a similar naming convention as above except for the file extension:
Note: Each daily tar archive may contain up to five files. However, only the daily tar archives associated with snowfall events will include all five files. Further information on the files contained within the tar archives is available in the Data Format document. The IFloodS data files are archived in a daily tar format with the following naming convention:
where,
The tar files consist of ASCII encoded files containing information on each drop observed, the drop size distribution and integral precipitation parameters such as precipitation rate, reflectivity and mass-weighted mean diameter. The following files may be contained within the tar archive and follow a similar naming convention as above:
Note: Each daily tar archive may not contain all the above listed files. If an instrument did not collect any data or observe any precipitation on a given day, then no tar archive was created for that day. Additional 2DVD data sets, which are not contained within a daily tar archive but use a similar file naming convention, provide a summary of the precipitation events observed by the 2DVD during the entire campaign.
The Two-Dimensional Video Disdrometer data sets consist of ASCII (.txt) files which contain information on the velocity, size, and size distribution of individual hydrometeors. The LPVEx 2DVD data additionally contains binary preprocessed hydrometer files created by the instrument manufacturer's software (.hyd files). More detailed information on the Data Format and Data Levels on the LPVEx 2DVD and related data can be found in the DataFormat_2dvd_fieldCampaign.pdf document. More information on the data format and data levels on the MC3E 2DVD and related data can be found in the DataFormat_2dvd_mc3e.pdf document. The GCPEx 2DVD data additionally contains compressed binary files (.sno and .shd) which can be viewed graphically using VIEW_HYD and MAKE_SNO software available from Joanneum Research. Also, these files can be read using the SNO2ASC program, available from the data provider upon request. More detailed information on the Data Format and Data Levels of the GCPEx 2DVD data can be found in the DataFormat_2dvd_gcpex.pdf document. More information on the data format and data levels on the IFloodS 2DVD and related data can be found in the DataFormat_2dvd_ifloods.pdf document. Beard, K. V., 1976: Terminal velocity and shape of cloud and precipitation drops aloft. J. Atmos. Sci., 33, 851–864. Gunn, R. and G. D. Kinzer. 1949. The terminal velocity of fall for water drops in stagnant air. J. Meteor., 6, 243–248. Jaffrain, Joël, Alexis Berne, 2011: Experimental quantification of the sampling uncertainty associated with measurements from PARSIVEL Disdrometers. J. Hydrometeor, 12, 352–370. Schönhuber, M., G. Lammer, and W. L. Randeu, 2008: The 2D-video-distrometer, Precipitation: Advances in Measurement, Estimation and Prediction, S. Michaelides, Ed., Springer, 3-31. Tokay, A., A. Kruger, and W. Krajewski, 2001: Comparison of drop size distribution measurements by impact and optical disdrometers. J. Appl. Meteor., 40, 2083–2097. To order these data or for further information, please contact:
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