NASA GHRC Collaboration between NASA MSFC and The University of Alabama in Huntsville
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  • Measurements
  • Field Campaigns
    • Hurricane Science
      • GHRC has worked with NASA's Hurricane Science Research Program (HSRP) since the 1990's. We are the archive and distribution center for data collected during HSRP field campaigns, as well as the recent Hurricane Science and Severe Storm Sentinel (HS3) Earth Venture mission. Field campaigns provide for intensive observation of specific phenomena using a variety of instruments on aircraft, satellites and surface networks.

        GHRC also hosts a database of Atlantic and Pacific tropical storm tracks derived from the storm data published by the National Hurricane Center (NHC).
    • HS3 (2012-14)
      • Hurricane and Severe Storm Sentinel (HS3) is an Earth Ventures – Suborbital 1 mission aimed at better understanding the physical processes that control hurricane intensity change, addressing questions related to the roles of environmental conditions and internal storm structures to storm intensification.

        A variety of in-situ, satellite observations, airborne data, meteorological analyses, and simulation data were collected with missions over the Atlantic in August and September of three observation years (2012, 2013, 2014). These data are available at GHRC beginning in 2015.
    • GRIP (2010)
      • The Genesis and Rapid Intensification Processes (GRIP) experiment was a NASA Earth science field experiment in 2010 that was conducted to better understand how tropical storms form and develop into major hurricanes.

        The GRIP deployment was 15 August – 30 September 2010 with bases in Ft. Lauderdale, FL for the DC-8, at Houston, TX for the WB-57, and at NASA Dryden Flight Research Facility, CA for the Global Hawk.
    • TC4 (2007)
      • The NASA TC4 (Tropical Composition, Cloud and Climate Coupling) mission investigated the structure and properties of the chemical, dynamic, and physical processes in atmosphere of the tropical Eastern Pacific.

        TC4 was based in San Jose, Costa Rica during July 2007.

        The Real Time Mission Monitor provided simultaneous aircraft status for three aircraft during the TC4 experiment. During TC4, the NASA ER-2, WB-57 and DC-8 aircraft flew missions at various times. The science flights were scheduled between 17 July and 8 August 2007.
    • NAMMA (2006)
      • The NASA African Monsoon Multidisciplinary Analyses (NAMMA) campaign was a field research investigation based in the Cape Verde Islands, 350 miles off the coast of Senegal in west Africa.

        Commenced in August 2006, NASA scientists employed surface observation networks and aircraft to characterize the evolution and structure of African Easterly Waves (AEWs) and Mesoscale Convective Systems over continental western Africa, and their associated impacts on regional water and energy budgets.
    • TCSP (2005)
      • The Tropical Cloud Systems and Processes (TCSP) mission was an Earth science field research investigation focused on the study of the dynamics and thermodynamics of precipitating cloud systems and tropical cyclones. TCSP was conducted during the period July 1-27, 2005 out of the Juan Santamaria Airfield in San Jose, Costa Rica.

        The TCSP field experiment flew 12 NASA ER-2 science flights, including missions to Hurricanes Dennis and Emily, Tropical Storm Gert and an eastern Pacific mesoscale complex that may possibly have further developed into Tropical Storm Eugene.
    • ACES (2002)
      • The Altus Cumulus Electrification Study (ACES) was aimed at better understanding the causes and effects of electrical storms.

        Based at the Naval Air Station Key West in Florida, researchers in August 2002 chased down thunderstorms using an uninhabited aerial vehicle, or "UAV", allowing them to achieve dual goals of gathering weather data safely and testing new aircraft technology. This marked the first time a UAV was used to conduct lightning research.
    • CAMEX-4 (2001)
      • The Convection And Moisture EXperiment (CAMEX) was a series of NASA-sponsored hurricane science field research investigations. The fourth field campaign in the CAMEX series (CAMEX-4) was held in 16 August - 24 September, 2001 and was based out of Jacksonville Naval Air Station, Florida.

        CAMEX-4 was focused on the study of tropical cyclone (hurricane) development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation.
    • CAMEX-3 (1998)
      • The Convection And Moisture EXperiment (CAMEX) is a series of hurricane science field research investigations sponsored by NASA. The third field campaign in the CAMEX series (CAMEX-3) was based at Patrick Air Force Base, Florida from 6 August - 23 September, 1998.

        CAMEX-3 successfully studied Hurricanes Bonnie, Danielle, Earl and Georges, yielding data on hurricane structure, dynamics, and motion. CAMEX-3 collected data for research in tropical cyclone development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation.
    • GPM Ground Validation
      • The NASA Global Precipitation Measurement Mission (GPM) Ground Validation (GV) program includes the following field campaigns:

        a) LPVEx, Gulf of Finland in autumn 2010, to study rainfall in high latitude environments

        b) MC3E, cental Oklahoma spring and early summer 2011, to develop a complete characterization of convective cloud systems, precipitation and the environment

        c) GCPEx, Ontario, Canada winter of 2011-2012, direct and remove sensing observations, and coordinated model simulations of precipitating snow.

        d) IFloodS, Iowa, spring and early summer 2013, to study the relative roles of rainfall quantities and other factors in flood genesis.

        e) IPHEx, N. Carolina Appalachians/Piedmont region May-June 2014, for hydrologic validation over varied topography.

        f) OLYMPEx, Washington's Olympic Peninsula scheduled November 2015-February 2016, for hydrologic validation in extreme coastal and topographic gradients
    • OLYMPEX (Upcoming)
      • The OLYMPEX field campaign is scheduled to take place between November, 2015, and February, 2016, on the Olympic Peninsula in the Pacific Northwest of the United States.

        This field campaign will provide ground-based validation support of the Global Precipitation Measurement (GPM) satellite program that is a joint effort between NASA and JAXA.

        As for all GPM-GV campaigns, the GHRC will provide a collaboration portal to help investigators exchange planning information and to support collection of real-time data as well as mission science, project and instrument status reports during the campaign.
    • IPHEx (2014)
      • The Integrated Precipitation and Hydrology Experiment (IPHEx) was conducted in North Carolina during the months of April-June, 2014.

        IPHEx sought to characterize warm season orographic precipitation regimes, and the relationship between precipitation regimes and hydrologic processes in regions of complex terrain.
    • IFLOODs (2013)
      • The Iowa Flood Studies (IFloodS) experiment was conducted in the central to northeastern part of Iowa in Midwestern United States during the months of April-June, 2013.

        IFloodS' primary goal was to discern the relative roles of rainfall quantities such as rate and accumulation as compared to other factors (e.g. transport of water in the drainage network) in flood genesis.
    • GCPEX (2011-2012)
      • The GPM Cold-season Precipitation Experiment (GCPEx) occurred in Ontario, Canada during the winter season (Jan 15- Feb 26) of 2011-2012.

        GCPEx addressed shortcomings in GPM snowfall retrieval algorithm by collecting microphysical properties, associated remote sensing observations, and coordinated model simulations of precipitating snow. Collectively the GCPEx data set provides a high quality, physically-consistent and coherent data set suited to the development and testing of GPM snowfall retrieval algorithm physics.
    • MC3E (2011)
      • The Mid-latitude Continental Convective Clouds Experiment (MC3E) took place in central Oklahoma during the April–June 2011 period.

        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.
    • LPVEx (2010)
      • The Light Precipitation Evaluation Experiment (LPVEx) took place in the Gulf of Finland in September and October, 2010 and collected 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.

        In doing so, LPVEx sought to address the general lack of dedicated ground-validation datasets from the ongoing development of new or improved algorithms for detecting and quantifying high latitude rainfall
  • Projects
    • HS3 Suborbital Mission
      • Hurricane and Severe Storm Sentinel (HS3) is an Earth Ventures – Suborbital 1 mission aimed at better understanding the physical processes that control hurricane intensity change, addressing questions related to the roles of environmental conditions and internal storm structures to storm intensification.
      • DISCOVER was funded by NASA’s MEaSUREs program to provide highly accurate, multi-decadal geophysical products derived from satellite microwave sensors.
    • LIS Mission
      • Lightning observations from the Lightning Imaging Sensors (LIS) aboard the NASA’s TRMM satellite and International Space Station, as well as airborne observations and ground validation data.
    • SANDS
      • The SANDS project addressed Gulf of Mexico Alliance priority issues by generating enhanced imagery from MODIS and Landsat data to identify suspended sediment resulting from tropical cyclones. These tropical cyclones have significantly altered normal coastal processes and characteristics in the Gulf region through sediment disturbance.
      • The Land, Atmosphere Near real-time Capability for EOS (LANCE) system provides access to near real-time data (less than 3 hours from observation) from AIRS, AMSR2, MLS, MODIS, and OMI instruments. LANCE AMSR2 products are generated by the AMSR Science Investigator-led Processing System at the GHRC.
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      • The GHRC Innovations Lab is a showcase for emerging geoinformatics technologies resulting from NASA-sponsored research at the University of Alabama in Huntsville.
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Guide Documents

Dataset PI Documents

Dataset Software

CAMEX-4 ER-2 Doppler Radar

Table of Contents

File Naming Convention
Data Format
Software Provided
Contact Information


The ER-2 Doppler radar (EDOP) is an X-band (9.6 GHz) Doppler radar mounted in the nose of ER-2. The instrument has two fixed antennas, one pointing at nadir and the second pointing approximately 33 degree ahead of nadir. The beam width of the antenna is 3 degrees in the vertical and horizontal directions which, for a 20 km altitude, yields a nadir footprint at the surface of 1 km. The ER-2 ground speed is nominally 210 m/s and the integration period used by the data system is 0.5 second. The transmit pulse is 0.5 second and the gate spacing is over sampled at 37.5 meter interval. Minimum detectable reflectivity is about -10 dBZ at an altitude of 15 km with a 0.375 meters range gate spacing. Additional details of the radar and processing are described by Heymsfield et al. (1996).

More detailed information about the ER-2 Doppler Radar may be found at the EDOP Home Page.

NOTE: Use of these files requires the commercial visualization program IDL available from ITT Visual Information Solutions.

File Naming Convention

EDOP files are 'tarred' together into daily (mission) files that appear as follows:


where YYYY.JJJ is the year and day of the year

When 'untarred' the tar file yields numerous swath data files named as follows:


where yymmdd is 2 digit year (99) mm is month, dd is day
ssss and eeee is the start and end time of the swath in UTC.

Data Format

EDOP data is in Universal Format (UF) as documented in the which is included with each dataset. IDL software is provided for reading the data.

EDOP currently collects data at a rate of 2 Hz from 4 Doppler channels with 738 gates. See paragraph 4 below for more information

Nadir rain (dynamic range optimized for rain signal -10-70 dBZ)
Nadir surface (dynamic range optimized for surface 20-100 dBZ)
Forward Co-polarization
Forward Cross-polarization

Each of these channels provides reflectivity, Doppler velocity, and spectral width estimated from the time series (autocovariance) approach.

Four levels of UF format are implemented for EDOP data:

Level 1: Conversion of EDOP uncalibated raw data format to UF
(uncalibrated power, Doppler velocity).
Level 2: Conversion of uncalibrated power to calibrated dBZ
Level 3: Doppler unfolding and aircraft motion removal.
Level 4: Attenuation correction of reflectivity.

The current distribution (Version 1) is in Level 2 format, and will have a ".uf.1" or ".caluf.1" appended to the file name. The ".1" is the version number; updated data sets will have higher numbers. All data files without a number appended are Version 0 and should be replaced with higher versions of the data. The parameter names for the Level 2 files are as follows:

PN Nadir_VV power
PS Nadir_VV surface power

DN Nadir_VV raw Doppler velocity [m/s]
DS Nadir_VV raw surface Doppler velocity [m/s]

ZN Nadir_VV reflectivity (dBZ)
ZS Nadir_VV surface reflectivity (dBZ)


The calibration of EDOP is described in Caylor et al. (1995), although this has been modified somewhat due to the change to the new digital-IF receiver and processing system in 1998. After the calibration is obtained, EDOP surface measurements (sigma_0) from both the nadir and forward beams are compared with previously published values as well as with statistics from TRMM estimated values. In addition, the reflectivity measurements in rain are compared with simultaneous measurements from the TRMM Precipitation Radar and several ground-based radars. However, only the EDOP internal and external calibrations are used, and NO adjustments are made to the EDOP reflectivities (unless otherwise noted) based on these comparisons. EDOP has a linear receiver so all calculations are performed linearly. Thus, if any error in calibration exists, the bias will be constant over the full dynamic range of the measurements. The final calibration of EDOP should be accurate to approximately 1 dBZ.

Software Provided

In addition to the file mentioned in paragraph 3 above, two other documentation files are provided for your use. The first is the EDOP_README which was written by the dataset producer, Dr. Heymsfield. In addition is a file named EDOP-UF.txt that provides a text version of the Universal format for EDOP data (level 1). These three files are included as separate files in your dataset, but each are tarred into the dataset itself. Each of these (and the tarred software file) may also be found on our anonymous FTP site.

There is a file named software.tar that will, when expanded, provide you with numerous program files to be used with IDL that will extract specific pieces of information from the EDOP data files. One such file, is shown below:

NOTE: This is only one example of the numerous IDL programs that will be found once the software.tar file is 'untarred'.

; USAGE: qview_demo, filename
;        ARGUMENTS    filename   Name of UF disk file
; ABSTRACT:  Demonstration program to read a relative power field and 
;          display
; AUTHOR:  I. Jeff Caylor
;          Science Systems and Applications, Inc.
;          5900 Princess Garden Parkway, Suite 300
;          Lanham, MD  20706
;     at:  NASA Goddard Space Flight Center
;          Code 912
;          Greenbelt, MD 20771
;          Voice: (301) 286-3767
;          Fax:   (301) 286-1762
;          Email:
; CREATED: 10 April 1995
; MODIFIED: 11 April 1995 - IJC
;           Changed rotate code from 2 to 7
;           13 July 1998  -LT
;           Change count field to relative power field (no cuont field)
PRO qview_demo, filename
  PRINT, 'Reading file: ', filename
  OPENR, infile, filename, /GET_LUN
  counts = fltarr(1500, 729)
  i = 0
  WHILE (EOF(infile) NE 1)  DO  BEGIN
    UF_read_dwell, infile, ufbuf, /RDSS
;   Extract nadir count data from the UF buffer
;help, i
    UFnameddata, ufbuf, 'pn', nc, ngates, ERROR = status
    counts(i, 0 : ngates - 1) = nc
    print, UFstrtime(ufbuf), UFdwell(ufbuf), UFedop_ins_altitude(ufbuf), $
           UFedop_ins_latitude(ufbuf), UFedop_ins_longitude(ufbuf), ngates
    i = i + 1
  CLOSE, infile
  FREE_lun, infile
; Trim array and rotate
  counts = counts(0 : i - 1, 0 : ngates - 1)
;  counts = rotate(counts, 7)
; Display
  image_cont, counts

Caylor I.J., G.M. Heymsfield, S. Bidwell, and S. Ameen, 1994: NASA-ER-2 Doppler radar reflectivity calibration for the CAMEX project. NASA Tech Memo 104611, 15 pp.

Heymsfield, G. M., S. Bidwell, I. J. Caylor, S. Ameen, S. Nicholson, W. Boncyk, L. Miller, D. Vandemark, P. E. Racette, and L. R. Dod, 1996: The EDOP radar system on the high-altitude NASA ER-2 aircraft. J. Atmos. Oceanic Tech., 13, 795-809.

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



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