The MMP/NCAR (National Center for Atmospheric Research) data set is part of the atmospheric measurements collected in the intensive observation period of the Tropical Ocean Global Atmosphere-Coupled Ocean Atmosphere Response Experiment (TOGA-COARE). This data was collected and processed under the direction of Principal Investigator Andy Heymsfield of NCAR and is archived at the Goddard DAAC.
MMP was part of the NASA TOGA-COARE campaign. The NASA component, while contributing to overall COARE objectives, emphasized the scientific objectives associated with the Tropical Rainfall Measuring Mission (TRMM) and NASA's cloud and radiation research programs.
2.1 Instrument Mission and Objectives
The MMP/NCAR consisted of four instruments installed and operated by NCAR aboard the NASA DC-8. Each instrument is listed here with the data parameters it provides. Six parameters are derived from the instrument measurements; the seventh parameter, vertical velocity, is calculated using data from the NASA DC-8 DADS.
- NCAR temperature probe
- Ambient temperature in degrees Celsius
- Total temperature (air+dynamic heating) in degrees Celsius
- NCAR Cryogenic frost point hygrometer
- Calibrated cryogenic dew point temperature in degrees Celsius
- Calibrated cryogenic frost point temperature in degrees Celsius
- Rosemont ice accretion probe
- change in voltage over change in time (dV/dt) in millivolts per second (mV/s)
- Lyman-Alpha sensor:
- Raw voltage output of the sensor in volts
- Calculated from DC-8 DADS data:
- Vertical velocity in meters per second
2.2 Instrument measurements and parameters
Following are the data parameters from the MMP data set as listed in the header of each data file. The prefix "NCAR" on the second through the fourth parameters is to distinguish them from their counterparts acquired by the DC-8 DADS.
Time(hrmnsc) - UTC time - acquired from the DC-8 DADS
- NCAR Ambient Temp(C)
- The calibrated ambient temperature from NCAR's temperature probe 102AU1AF, serial number 41716, in degrees Celsius. The sensor was post flight calibrated from 40 to -45 degrees C with a linear curve fit in the NCAR/RAF Calibration laboratory to + or - 0.1 degrees C. A recovery factor was determined from aircraft maneuvers that were performed on flight number 18. The heating effects of the de-icing probe were also corrected for. The NASA DADS data mach number and pressure value were used to calculate the NCAR Ambient Temperature. This value at worst case is + or - 1 degrees Celsius.
- NCAR Total Temp(C)
- The calibrated total temperature from NCAR's temperature probe. Same comments as above for ambient temp.
- NCAR Dew Pt(C)
- The calibrated cryogenic dew point temperature from NCAR'scryogenic frost point hygrometer unit #1 in degrees Celsius. The mirror temperature was pre flight calibrated from -15 to -80 degrees C in the NCAR/RAF Calibration laboratory to an absolute value of + or - 0.3 degrees C. The inlet pressure was calibrated to + or - .6 millibars. The NASA DADS data pressure value and the NCAR ambient temperature were used with the cryo mirror temperature and cryo inlet pressure to calculate the Dew point temperature, which should be within +/- 1.5 degrees C. An offset of -4.2 degrees C should be added to the dew pt to account for addition calibration based on observations. You should contact the PI about this parameter to find out the latest information.
- NCAR Frost Pt(C)
- The calibrated cryogenic frost point temperature from NCAR's cryogenic frost point hygrometer. Same comments as above for dew pt.
- Icing Probe(dV/dt)(mV/s)
- The change in voltage over change in time of the Rosemount 871F ice-accretion probe in millivolts per second. The data was recorded with 5 mV/s resolution and the instrument can bounce with about 10 mV/s of noise when nothing is present so we recommend that a value of at least 15 mV/s for a 2 or 3 second time period be used as a detection threshold for liquid water.
- Lyman Alpha(Volt)
- The raw voltage output of the Lyman-alpha sensor, which is related to water vapor density. The light source intensity drifts from flight to flight, hence voltage is a relative measure of water vapor density changes.
- NCAR Vertical Velocity Calculation(m/s)
- The calculated vertical air velocity in meters per second. The vertical velocity was calculated with a method used in the past by NCAR (Lenschow 1976, Monthly Weather Review). The method uses such things as coefficient of lift at zero angle of attack, the take-off weight of the aircraft, the burn rate, the density, the true airspeed, etc . Since the aircraft's weight and burn rate had to be estimated (from NASA), the vertical velocities are offset for each flight(usually about -2 to -6 m/s). This offset sometimes changes during the flight if the burn rate estimate differs greatly from the actual burn rate. These offsets can be corrected by simply adding the average offset for the appropriate time period. This calculation loses accuracy when the plane has a roll of greater than about +/-3 degrees, therefore a dummy value of 99999 is placed in the data set when that occurs. The vertical velocity calculation is also averaged over a 9 second period, because of the characteristic response time of the calculations. The investigators have not yet fully analyzed the values, but are confident that they give a very good qualitative estimate, and a good quantitative estimate of the vertical air velocities.
3.1 General DescriptionThe MMP data is about 26 MB in total volume with a typical file size of about 2.2 MB. It consists of 12 ascii files named "mmparchive.fnXX", where XX is a 2 digit flight number. The MMP produced data on 12 of the 13 mission flights made by the NASA DC-8 during the TOGA COARE campaign.The following table relates MMP data files to ER-2 and DC-8 flight numbers and dates for the 13 mission flights of the NASA/TOGA COARE campaign. The objectives column (Obj) is included for the convenience of the user; the mission objective was convection (Con) when it was forecast in the target area and radiation (Rad) when it was not.
Date(UTC) ER-2 Flight DC-8 Flight MMP File Objective Jan 11-12 93-053 93-01-06 Radiation Jan 17-18 93-054 93-01-07 mmparchive2.fn07 Convection Jan 18-19 93-055 93-01-08 mmparchive2.fn08 Convection Jan 25-26 93-056 93-01-09 mmparchive2.fn09 Radiation jan 31-Feb 1 93-057 93-01-10 mmparchive2.fn10 Radiation Feb 4 93-060 93-01-11 mmparchive2.fn11 Convection Feb 6 93-01-12 mmparchive2.fn12 Convection Feb 7 93-061 Feb 8-9 93-062 93-01-13 mmparchive2.fn13 Convection Feb 10-11 93-063 93-01-14 mmparchive2.fn14 Convection Feb 17-18 93-01-15 mmparchive2.fn15 Convection Feb 20-21 93-065 93-01-16 mmparchive2.fn16 Convection Feb 22-23 93-066 93-01-17 mmparchive2.fn17 Convection Feb 23-24 93-067 93-01-18 mmparchive2.fn18 Radiation 3.2 Data format
Each MMP data file begins with a file header followed by the data in tabular format. An example of the file contents is shown below.TOGA COARE DC-8 Flight 93-01-07 format (i6,7f11.4) Time(hrmnsc), NCAR Ambient Temp(C), NCAR Total Temp(C), NCAR Dew Pt(C), NCAR Frost Pt(C), Icing Probe(dV/dt)(mV/s), Lyman Alpha(Volt), NCAR Vertical Velocity Calculation(m/s) 231010 -63.5556 -50.6920 99999.0000 99999.0000 0.0000 -2.0560 -1.8840 231011 -63.5556 -50.6920 99999.0000 99999.0000 0.0000 -2.0900 -2.6133 231012 -63.5988 -50.6920 99999.0000 99999.0000 0.0000 -2.0850 -3.3396 231013 -63.5988 -50.6920 99999.0000 99999.0000 0.0000 -2.0950 -4.0531 231014 -63.6421 -50.6920 99999.0000 99999.0000 0.0000 -2.0460 -4.7766 231015 -63.7371 -50.7929 99999.0000 99999.0000 -4.8830 -2.0220 -6.3676 231016 -63.6855 -50.6920 99999.0000 99999.0000 0.0000 -2.0310 -6.3727 231017 -63.7289 -50.6920 99999.0000 99999.0000 4.8830 -2.0170 -6.4841 231018 -63.7289 -50.6920 99999.0000 99999.0000 -4.8830 -2.0310 -6.6852
4.1 FTP access to MMP data
MMP data on FTP
5.1 Times. UTC times were acquired from the DC-8 DADS.
5.2. Data quality factors. Factors to be considered in assigning a quality value to the output from each instrument are discussed in Section 2.2 above.
5.3 Bad or missing data values. The value 99999.0000 is used to designate missing or bad data (i.e., when vertical air velocity calculations went bad because of aircraft roll, or when cryo went above -15 degrees C (Cryo measurements only valid below -15 degrees C),etc.).
- For information about or assistance in using any NASA/TOGA COARE data, contact:
- Pat Hrubiak
- EOS Distributed Active Archive Center(DAAC)
- Code 610.2
- NASA Goddard Space Flight Center
- Greenbelt, Maryland 20771
- Internet: hrubiak@disc.gsfc.nasa.gov
- 301 614-5165 (voice)
- 301 614-5268(fax)
- For detailed information about the sensor or data, contact the Principal Investigator:
- Andy Heymsfield
- NCAR/MMM
- PO Box 3000
- Boulder, Colorado 80307
- Internet: heyms1@ncar.ucar.edu
- (303) 497-8943 (voice)
- (303) 497-8181 (FAX)
NASA/TOGA COARE Science Data Workshop II, Proceedings of a workshop held in Albuquerque, New Mexico, March 15-17, 1994, July 1994, NASA TOGA COARE Project Office, NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666.Mission Summary Reports, TOGA COARE, November 1993, NASA TOGA COARE Project Office, NASA Langley Research Center, Mail Stop 483, Hampton, VA 23666
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