Global Hydrology Resource Center(GHRC) is one of NASA's Earth Science Data Centers and is a collaboration between MSFC and University of Alabama in Huntsville

GPM Ground Validation Autonomous Parsivel Unit (APU)
Field Campaign: LPVEX, MC3E

Table of Contents

Introduction
Campaigns
     LPVEx
     MC3E
Instrument Description
Data Producers
File Naming Convention
     LPVEx
     MC3E
Data Format
Citation
Contact Information

Introduction

The Autonomous Parsivel Unit (APU) provides a means for measuring the particle size and fall velocity of all liquid and solid precipitation. It consists of a Parsivel, which is an optical disdrometer developed by OTT Messtechnik in Germany, and its support systems, which were designed and built by the University of Alabama in Huntsville.

Campaigns

The 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).

LPVEx

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 parsivel data files provide spectrum observations, drop size distributions, rainfall parameters, and measured snowfall. . More detailed information on the parsivel and related instruments and their data levels for LPVEx can be found in the LPVEx_Dataset_summary.

The APU instruments were located at 3 sites in Finland: Harmaja, Emasalo, and Jarvenpaa. The instrument name and coordinates of these sites are:

Harmaja:
      apu05 ; Lat: 60 degrees 06' 16.12" N ; Lon: 24 degrees 58' 28.44" E; Orientation N-S
      apu09; Lat: 60 degrees 06' 16.08" N ; Lon: 24 degrees 58' 28.30" E; Orientation: E-W
Emasalo:
      apu07; Lat: 60 degrees 12' 13.28"N ; Lon: 25 degrees 37' 27.98" E; Orientation N-S
      apu08; Lat: 60 degrees 12' 13.44" N; Lon: 25 degrees 37' 28.20" E; Orientation: E-W
Jarvenpaa:
      apu03; Lat: 60 degrees 29' 04.92" N; Lon: 25 degrees 04' 55.22" E; Orientation N-S
      apu04; Lat: 60 degrees 29' 05.00" N; Lon: 25 degrees 04' 55.41" E; Orientation: E-W

MC3E

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 overarching 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 parameterizations and space-based rainfall retrieval algorithms over land that had never before been available.

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 APU instruments were located at 17 stations in Oklahoma. The stations and coordinates are:

      apu01:   Lat: 36 degrees 36' 29.79" N ; Lon: 97 degrees 28' 18.08" W
      apu02:   Lat: 36 degrees 36' 29.69" N ; Lon: 97 degrees 30' 23.27" W
      apu03:   Lat: 36 degrees 38' 00.27" N ; Lon: 97 degrees 29' 56.22" W
      apu04:   Lat: 36 degrees 38' 16.99" N ; Lon: 97 degrees 27' 57.63" W
      apu05:   Lat: 36 degrees 38' 06.71" N ; Lon: 97 degrees 31' 01.06" W
      apu06:   Lat: 36 degrees 38' 13.43" N ; Lon: 97 degrees 32' 35.51" W
      apu07:   Lat: 36 degrees 36' 55.22" N ; Lon: 97 degrees 33' 07.90" W
      apu08:   Lat: 36 degrees 36' 53.93" N ; Lon: 97 degrees 30' 58.16" W
      apu09:   Lat: 36 degrees 35' 38.04" N ; Lon: 97 degrees 29' 19.79" W
      apu10:   Lat: 36 degrees 35' 37.17" N ; Lon: 97 degrees 30' 26.43" W
      apu11:   Lat: 36 degrees 34' 42.51" N ; Lon: 97 degrees 29' 54.66" W
      apu12:   Lat: 36 degrees 34' 08.40" N ; Lon: 97 degrees 28' 47.41" W
      apu13:   Lat: 36 degrees 34' 43.76" N ; Lon: 97 degrees 27' 45.32" W
      apu14:   Lat: 36 degrees 35' 58.62" N ; Lon: 97 degrees 25' 34.21" W
      apu15:   Lat: 36 degrees 34' 42.44" N ; Lon: 97 degrees 25' 35.89" W
      apu16:   Lat: 36 degrees 33' 50.78" N ; Lon: 97 degrees 27' 12.18" W
      apu17:   Lat: 36 degrees 36' 13.75" N ; Lon: 97 degrees 29' 06.24" W

Instrument Description

The OTT parsivel disdrometer is a modern, laser-based optical system for measuring all types of precipitation. The transmitter unit of the sensor generates a flat, horizontal beam of light, which the receiver converts into an electrical signal. The signal changes whenever a hydrometeor falls through the beam anywhere within the measurement area. The degree of dimming is a measure of the size of the hydrometeor, and together with the duration of the signal, the fall velocity can be derived.

Additional information about the APU Parsivel disdrometer can be found in the following document: Parsivel Operator Instructions.

Data Producers

Walter A.Peterson
NASA Wallops Flight Facility
Wallops Island, VA 233375

Larry Carey
Earth Systems Science Center
UAHuntsville
Huntsville, AL 35805

Patrick Gatlin
Earth Science Office
NASA-MSFC
Huntsville, AL 35805

File Naming Convention

LPVEx

Data are in two forms, cumulative snowtable files and daily tared files:

parsivel_apuxx_Jarvenpaa_snowtable.txt
<apuxx>_<site>_yyyymmdd.tar

where

parsivel = instrument name
apu = Autonomous Parsivel Unit (apuxx or gvp01)
xx = station identifier
site = location of the instrument designated in the Field Experiments (e.g. LPVEX:
           Harmaja, Emasalo, Jarvenpaa [Finland] )
yyyymmdd = year, month and day of the data
tar = Unix "tape archive" format
txt = ASCII data file

The tar files contain both level 1a (spectrum observations) and level 3 (dsd, rainParams) data files as described below. Not all type files are in each tar bundle.

parsivel_<site>_yyyymmdd_spectrum.txt - spectrum observations
parsivel_apuXX_<site>_yyyymmdd_dsd.txt - drop size distribution
parsivel_apuXX_<site>_yyyymmdd_rainParams.txt - rainfall parameters
parsivel_apuXX_<site>_yyyymmdd_snowtable.txt - measured snowfall

MC3E

Data are in two forms, rainfall amount files and daily tared files:

parsivel_<apuxx>_mc3e_<latitude_longitude>_raintable.txt
parsivel_<apuxx>_mc3e_<latitude_longitude>_yyyymmdd.tar

where

parsivel = instrument name
apu = Autonomous Parsivel Unit
xx = station identifier
mc3e = Midlatitude Continental Convective Clouds Experiment
latitude_longitude = geographic location of the instrument
yyyymmdd = year, month and day of the data
tar = Unix "tape archive" format
txt = ASCII data file

The following ASCII files are contained within the tar archive:

parsivel_<apuxx>_mc3e_<latitude_longitude>_yyyymmdd_<parameter>.txt

The file naming convention is defined similarly as shown above. The types of parameters are as follows:

dropcounts = counts of hydrometeors
dsd = drop size distribution each minute hydrometeors were detected and binned by 0.2 mm
dsd_vT = terminal velocity based drop size distribution
rainParams = integrated rainfall parameters for each minute hydrometeors were detected
rainParams_vT = integral rainfall parameters calculated using terminal velocity
raw = raw instrument data

Data Format

The Autonomous Parsivel Unit datasets consist of ASCII (.txt) files containing rain rate, drop size distribution and information on hydrometeors. The LPVEx APU additionally contains spectrum observations and measured snowfall. More detailed information on the data format for the LPVEx APU can be found in the DataFormat_parsivel_fieldCampaign.pdf document. The format for data prior to Feb. 25, 2011 can be found in the Parsivel_raw_data_format_nsstc.pdf document.

Citation

Our data sets are provided through the NASA Earth Science Data and Information System (ESDIS) Project and the Global Hydrology Resource Center (GHRC) Distributed Active Archive Center (DAAC). GHRC DAAC is one of NASA's Earth Observing System Data and Information System (EOSDIS) data centers that are part of the ESDIS project. ESDIS data are not copyrighted; however, in the event that you publish our data or results derived by using our data, we request that you include an acknowledgment within the text of the article and a citation on your reference list. Examples for general acknowledgments, data set citation in a reference listing, and crediting online web images and information can be found at: http://ghrc.nsstc.nasa.gov/uso/citation.html

Contact Information

To order these data or for further information, please contact:

Global Hydrology Resource Center
User Services
320 Sparkman Drive
Huntsville, AL 35805
Phone: 256-961-7932
E-mail: ghrcdaac@itsc.uah.edu
Web: http://ghrc.nsstc.nasa.gov/