GPM Ground Validation NCAR Cloud Microphysics Particle Probes
Field Campaigns: MC3E, GCPEx

Table of Contents

Introduction

The GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E and GCPEx datasets were acquired from three instruments carried aboard the University of North Dakota (UND) Cessna Citation aircraft. These instruments, the Two-Dimensional Optical Array Cloud Probe (2D-C), the Cloud Imaging Probe (CIP) and the High Volume Precipitation Spectrometer (HVPS-3), collected cloud particle size distributions and cloud particle imagery. The GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E and GCPEx datasets were processed from the cloud particle data by NCAR and include derived parameters such as ice water content, liquid water content, and total number concentration. These datasets are available in ASCII format. Browse imagery of these datasets are also available in .png format.

Citation

The following examples show how to cite the use of these datasets in a publication. For more information, please see our Citing GHRC DAAC and Data page.

Heymsfield, A., A. Bansemer, and M. Poellot. 2011. GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E [indicate subset used]. Dataset 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:

Heymsfield, A., A. Bansemer, and M. Poellot. 2012. GPM Ground Validation NCAR Cloud Microphysics Particle Probes GCPEx [indicate subset used]. Dataset 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/GCPEX/MUTIPLE/DATA201

Campaigns

The Global Precipitation Measurement (GPM) mission Ground Validation (GV) campaign used a variety of methods for validation of GPM satellite constellation measurements prior to the launch of the GPM Core Satellite, which was launched February 27, 2014. The validation effort entailed numerous GPM-specific and joint-agency/international external field campaigns and used state of the art cloud and precipitation observational infrastructure (polarimetric radars, profilers, rain gauges, disdrometers). Surface rainfall was measured by very dense rain gauge and disdrometer networks at various field campaign sites. These field campaigns accounted for the majority of the effort and resources expended by Global Precipitation Measurement (GPM) mission Ground Validation (GV).

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

NCAR Cloud Microphysics Particle Probes data for MC3E was collected from 22 April to 2 June 2011.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/.

GCPEx

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.

NCAR Cloud Microphysics Particle Probes data for GCPEx was collected from 16 January to 25 February 2012. Further details on GCPEx are available at http://gpm.nsstc.nasa.gov/gcpex.

Instrument Descriptions

UND Cessna Citation II

The UND Cessna Citation II Research Aircraft used for the MC3E and GCPEx experiments is owned and operated by the University of North Dakota. The Citation II is a twin-engine fanjet with an operating ceiling of 43,000 feet (13.1 km). The turbofan engines provide sufficient power to cruise at speeds of up to 340 knots (175 m s-1) or climb at 3300 feet per minute (16.8 m s- 1). These high performance capabilities are accompanied by relatively low fuel consumption at all altitudes, giving the Citation an on-station time of 3-5 hours, depending on mission type. Long wings allow it to be operated out of relatively short airstrips and to be flown at the slower speeds (140 kts/72 m s-1) necessary for many types of measurements. The Citation is certified for flight into known icing conditions. Further details on the UND Cessna Citation II are available at http://cumulus.atmos.und.edu/.

CIP

The Cloud Imaging Probe (CIP), manufactured by Droplet Measurement Technologies, is a particle spectrometer that measures the size and shape of cloud particles from 75-1550 micrometers. The CIP uses a 64-element linear diode array at an image resolution of 25 micrometers per pixel. Particle size distributions, derived parameters, and particle images are available from the CIP.

HVPS

The High Volume Precipitation Spectrometer version 3 (HVPS or HVPS-3), manufactured by SPEC, Inc., is an airborne particle spectrometer that measures the size and shape of cloud particles from 0.3 micrometers to 2.5 centimeters. The HVPS uses a 128-element linear diode array at an image resolution of 150 micrometers per pixel. Particle size distributions, derived parameters, and particle images are available from the HVPS.

2D-C

The Two-Dimensional Optical Array Cloud Probe (2D-C) , manufactured by Particle Measuring Systems, Inc, provides two-dimensional images of hydrometeors. The 2D-C records as an image the two-dimensional shadow cast by a hydrometeor as it passes through a laser beam. The 2D-C measures the size and shape of cloud particles from 75 - 1900 micrometers in size and uses a 32-element linear diode array at an image resolution of 30 micrometers per pixel. Particle size distributions, derived parameters, and particle images are available from the 2D-C.

Investigators

Andrew Heymsfield
NCAR
P.O. Box 3000
Boulder, CO 80307-3000

Aaron Bansemer
NCAR
P.O. Box 3000
Boulder, CO 80307-3000

Michael Poellot
University of North Dakota
4149 University Avenue
Stop 9006
Grand Forks, ND 58202-9006

The GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E and GCPEx data sets are contained within daily ASCII text files. Each instrument's data is in separate files. These files are named with the following convention:

YYYYMMDD_HHMMSS.comb.spectrum.1Hz
YYYYMMDD_HHMMSS.HVPS3.1Hz
YYYYMMDD_HHMMSS.CIP.1Hz
YYYYMMDD_HHMMSS.2DC.1Hz

and the GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E and GCPEx browse files are named with the following convention:

YYYYMMDD_HHMMSS_2DC7.png
YYYYMMDD_HHMMSS_HVPS3.png
YYYYMMDD_HHMMSS_CIP.png

where,

YYYYMMDD = the year, month and day of the data
HHMMSS = the hour, minutes, and seconds of the data
comb.spectrum = all 3 instruments (HVPS3, CIP, 2DC) combined
HVPS3 = High Volume Precipitation Spectrometer- 3
CIP = Cloud Imaging Probe
2DC = 2-D Cloud Probe
Hz = Hertz
png = portable network graphics, a raster graphics file format

The comb.spectrum file combines the results of all three of the probes into a single particle size distribution. The CIP or 2D-C data was used for particles smaller than 1 millimeter and the HVPS-3 was used for particles larger than 1 millimeter. The choice between the CIP and the 2D-C for smaller particles was based on data quality with the CIP being the first priority because it was the more modern of the two probes.

The GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E and GCPEx datasets consist of ASCII files. The ASCII files contain data that is recorded every second during the flight.

The GPM Ground Validation NCAR Cloud Microphysics Particle Probes MC3E and GCPEx datasets also include browse images in .png format. The browse images represent one minute of flight time with one panel in the image representing 5 seconds of flight time.

References

Field, P. R., A. J. Heymsfield, and A. Bansemer, 2006a: Shattering and particle interarrival times measured by optical array probes in ice cloud. J. Atmos. Oceanic Technol., 23, 1357–1371.

Knollenberg, Robert G., 1970: The Optical Array: An Alternative to Scattering or Extinction for Airborne Particle Size Determination. J. Appl. Meteor., 9, 86–103.

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/