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.

GRIP DC-8 Meteorological Measurement System

Table of Contents

System Description
File Naming convention
Format and content
Contact Information


The NASA DC-8 Meteorological Measurement System (MMS) is a proven instrument to measure accurate, high resolution, science quality, in situ airborne state measurements. The parameters measured are pressure, temperature, turbulence, and three-dimensional wind vectors. This system was developed at NASA Ames Research Center, has been operational since 1986, and has been successfully used in an impressive list of field campaigns, including: STEP, AAOE, AASE I, AASE II, SPADE, ASHOE/MAESA, SUCCESS, STRAT, SONEX, POLARIS, SOLVE, CAMEX-3/4, CRYSTALFACE, MidCix, AURA Validation Experiment and NAMMA.


The Genesis and Rapid Intensification Processes (GRIP) experiment was a NASA Earth science field experiment conducted August 5 to September 30, 2010. The major goal was to better understand how tropical storms form and develop into major hurricanes. NASA used the DC-8 aircraft, the WB-57 aircraft and the Global Hawk Unmanned Airborne System (UAS), configured with a suite of in situ and remote sensing instruments that were used to observe and characterize the lifecycle of hurricanes. This campaign also capitalized on a number of ground networks and space-based assets, in addition to the instruments deployed on aircraft from Ft. Lauderdale, Florida ( DC-8), Houston, Texas (WB-57), and NASA Dryden Flight Research Center, California (Global Hawk). More information about this Campaign can be found on the GRIP web site:

System Description

The MMS consists of three major systems: an air-motion sensing system to measure air velocity with respect to the aircraft, an aircraft-motion sensing system to measure the aircraft velocity with respect to the earth, and a data acquisition system to sample, process, and record the measured quantities.

The air-motion system consists of two airflow-angle probes, three total temperature probes (each with a different response time), a pitot-static pressure probe, and a dedicated static pressure system. All probes and sensors are judiciously located at specific positions of the fuselage. The aircraft-motion sensing system consists of an embedded GPS ring laser inertial navigation system, and a multiple-antenna GPS attitude reference system. Customized software was developed to control, sample, and process all sensors and hardware.

Since the MMS provides quality information on atmospheric state variables, MMS data have been extensively used by many investigators to process and interpret the in situ experiments aboard the same aircraft.


The primary dataset, collecting all parameter types, is gathered at 20Hz. A subset of these data are created by averaging data over one or five second intervals, and reporting a 1Hz or 5Hz dataset of a reduced number of parameters. Primary and secondary products used by MMS are listed below.

The MMS data has been "QC'ed" and calibrated, with NIST traceable temperature bath calibaration of the sensor. The MMS data set are also calibrated for aerodynamic flrow compensation using inflight maneuvers.

More information can be found from the MMS Web site:

Primary Products

The primary data are collected at 20Hz and consists of all measured and calculated parameters. The header in each 20 HZ data file explains the data, and lists the parameters contained in each column. An example listing is shown in figure 1 below:


55 1001|
BUI, T. Paul; S. Bowen; L. Pfister; J. Dean-Day; C. Chang NASA - Ames Research Center; email: Meteorological Data from DC-8 MMS GRIP
1 1 ;ivol nvol
2006 08 09 2007 04 25 ;flight-date process-date
0 ;non-uniform time increment
Elapsed UT seconds of flight date
.1 .01 .01 .01 .01 .001 .01 .01 .001 .001 .1 .01
.01 .01 .01 .01 .01 .001 .01 .01 .01 .0001 .001 .001 .001
99999 99999 99999 999999 999999 999999 99999 9999 999999 9999999 999999 99999
99999 99999 99999 999999 999999 999999 999999 99999 99999 999999 999999 999999 999999
Static Pressure (Psta) mb 0.1 99999
Static Temperature * (Tsta) K 0.01 99999
True Air Speed * (TAS) m/s 0.01 99999
E-W Horizontal Wind Speed * (U) m/s 0.01 999999
N-S Horizontal Wind Speed * (V) m/s 0.01 999999
Vertical Wind Speed *@ (W) m/s 0.001 999999
LOG10 Turbulent Dissipation Rate (TEDR) Kw/Kg 0.01 99999
LOG10 Reynolds Number per Length (REYN) /m 0.01 9999
Latitude +N (LAT) deg 0.001 999999
Longitude +E (LONG) deg 0.001 9999999
Pressure Altitude (PALT) m 0.1 999999
Potential Temperature * (POT) K 0.01 99999
Roll Angle +right wing down (ROLL) deg 0.01 99999
Heading Angle (HDG) deg 0.01 99999
Pitch Angle (PITCH) deg 0.01 99999
N-S Ground Speed +N (Ydot) m/s 0.01 999999
E-W Ground Speed +E (Xdot) m/s 0.01 999999
Vertical Speed +U @ (Zdot) m/s 0.001 999999
Q (Compressible Dynamic Pressure) (q) mb 0.01 999999
Yaw Angle (sideslip angle) (YAW) deg 0.01 99999
Angle of Attack (AOA) deg 0.01 99999
Mach Number (MACH) 0.0001 999999
Vertical Acceleration +U (Zdotdot) m/ss 0.001 999999
Yaw delta P (Ydp) mb 0.001 999999
AOA delta P (Adp) mb 0.001 999999
@ Supressed when data gap is greater than 10 seconds
At the request of users in the meteorological community, more significant
figures are presented here than the resolution of the MMS measurements. For
discussion of resolution and accuracy of the MMS measurements, refer to Scott
et al, "The Meteorological Measurement System on the NASA ER-2 Aircraft",
J. Atmos. Ocean. Tech. 7, 525, 1990.

57211.823 9799 29766 7276 11 -209 484 -625 511 47957 -97402 2815 29939 12 18158 39 -7484 25 -473 3069 -169 115 2104 -45 -2220 -8148
57211.873 9799 29764 7312 6 -183 387 -593 506 47957 -97402 2814 29937 13 18159 44 -7495 25 -487 3101 -173 113 2114 -501 -2389 -8327
57211.923 9799 29775 7312 24 -192 203 -603 508 47957 -97402 2813 29948 15 18158 49 -7503 25 -512 3099 -159 106 2114 -530 -1693 -8484
57211.973 9799 29800 7288 69 -227 170 -594 517 47957 -97402 2810 29973 16 18158 54 -7514 25 -535 3076 -123 109 2106 -331 24 -8127

Secondary Products

Subsets of the primary data are created by averaging data over one or five second intervals, creating a dataset of a reduced number of parameters. These products may include measured parameters:

DGPS Positions, Velocities, Accelerations, Pitch, Roll, Heading, Angle-of-Attack, Angle-of-Sideslip, Dynamic & Total Pressures, Total Temperatures

and derived parameters:

Potential Temperature, True-Air-Speed, Turbulence

File Naming Convention

GHRC data holdings consist of a 20 Hz primary dataset, named as follows:


There are also secondary datasets derived from the primary at 5Hz or 1Hz sample rates. These datasets are named as follows:



GRIP = Campaign name
yyyymmdd = Year, Month, Day
XX = Type of secondary files (listed in "Format and Content" section)
txt = data in ASCII text files

Format and Content

"MM_20HZ" data:

This is the primary dataset, and the data are sampled at a 20 Hz rate. This dataset contains all
of the MMS parameters which consist of:

Static Pressure (Psta) mb
Static Temperature * (Tsta) K
True Air Speed * (TAS) m/s
E-W Horizontal Wind Speed * (U) m/s
N-S Horizontal Wind Speed * (V) m/s
Vertical Wind Speed *@ (W) m/s
LOG10 Turbulent Dissipation Rate (TEDR) Kw/Kg
LOG10 Reynolds Number per Length (REYN) /m
Latitude +N (LAT) deg
Longitude +E (LONG) deg
Pressure Altitude (PALT) m
Potential Temperature * (POT) K
Roll Angle +right wing down (ROLL) deg
Heading Angle (HDG) deg
Pitch Angle (PITCH) deg
N-S Ground Speed +N (Ydot) m/s
E-W Ground Speed +E (Xdot) m/s
Vertical Speed +U @ (Zdot) m/s 0.001
Q (Compressible Dynamic Pressure) (q) mb
Yaw Angle (sideslip angle) (YAW) deg
Angle of Attack (AOA) deg
Mach Number (MACH)
Vertical Acceleration +U (Zdotdot) m/ss
Yaw delta P (Ydp) mb
AOA delta P (Adp) mb

"MA" data:

This reduced parameter secondary dataset is sampled at a 5 Hz rate (from the 20 Hz data), and contains the following parameters:

GMT - Elapsed UT seconds of flight day
Pitch - Pitch angle (deg)
Roll - Roll angle (deg)
Head - Heading angle (deg)

The "FP", "MM" and "MG" reduced parameter secondary datasets are sampled at  a 1 Hz rate (from the 20 Hz data), and contain the following parameters:

"FP" data:

UT - Elapsed UT seconds of flight day
P_ALT - Pressure Altitude (m)
LAT - Latitude (deg)
LONG - Longitude (deg)
TAS - True Air Speed (m/s)

"MM" data:

GMT - Elapsed UT seconds of flight day
Psta - Static pressure (mb)
Tsta - Static temperature (deg K)
Thta - Potential temperature (deg K)
U - Horizontal E-W wind speed (m/s)
V - Horizontal N-S wind speed (m/s)
W - Vertical wind speed (m/s)

"MG" data:

UT - Elapsed UT seconds of flight day
DALT - GPS altitude (km)
DLAT - GPS latitude +N (deg)
DLONG - GPS longitude +E (deg)
TEDR - Log10 of Turbulent eddy dissipation rate (kw/kg)
REYN - Log10 of Reynolds number per unit length (/m)

Each of the dataset files contain a header which describes the data that follows. An example of the header portion of a "FP" data file is shown in figure 2 below. 


25 1001                                               ;header lines/format index
BUI, T. Paul                                         ; S. Bowen; L. Pfister; J. Dean-Day; C. Chang
NASA - Ames Research Center           ; email:
Meteorological Data from DC-8 MMS
1 1                                                        ;ivol nvol
2010 09 21 2011 03 15                        ;flight-date process-date
0                                                           ;0=non-uniform time increment
Elapsed UT seconds of flight date
4                                                           ;number of primary variables
1.0 0.001 0.001 0.1                              ;scale factors
99999 999999 9999999 9999              ;missing values
Pressure Altitude (m)
Latitude +N (deg)
Longitude +E (deg)
True Air Speed (m/s)
1Hz data are desampled from 20Hz data.
20Hz data file is available upon request, containing: GMTS,Psta,Tsta,TAS, U,V,W,TURB,REYN,LAT,LONG,PALT,POT,ROLL,HDG,PIT,Ydot,Xdot,Zdot,Q,YAW,AOA, MACH,Zdotdot,YAWdp,AOAdp (Approximately 12 MBytes per flight hour) C:\GRIP\RAWCV\D_100921.CVB
UT         P_ALT   LAT      LONG    TAS
56884.8    134    17703    -64785     885
56885.8    148    17703    -64785     872
56886.8    161    17703    -64784     861
56887.8    171    17703    -64783     856


Chan, K. R., S. W. Bowen, and J. D. Day, Observation of Turbulence by DC-8 MMS, presented at the AEAP Virginia Beach Meeting, VA, April 1997.

Bui, T. P., DC-8 Meteorological Measurement System, presented at the SONEX Workshop, NASA Ames Research Center, February 1997.

Gaines, S. E., S. W. Bowen, R. S. Hipskind, T.P. Bui, and K. R. Chan, Comparisons of the NASA ER-2 meteorological measurement system with radar tracking and radiosonde data, J. Atmos. Ocean. Tech., 9, 210-225, 1992

S.G. Scott, T.P. Bui, K. R. Chan, and S. W. Bowen, The meteorological measurement system on the NASA ER-2 aircraft, J. Atmos. Ocean. Tech., 7, 525-540, 1990

K. R. Chan, L. Pfister, T.P. Bui, S. W. Bowen, J. Dean-Day, B.L. Gary, D.W. Fahey, K.K. Kelly, C.R. Webster, and R. D. May, A case study of the mountain lee wave event of January 6 1992, Geophys. Res. Letters, 20, 2551-2554, 1993.

T.P. Bui, S. Bowen, C. Chang, J. DeanDay, L. Pfister, R. Castenada, P. Shulman,
Evaluating, WB-57F and ER-2 MMS measurement confidence, CRYSTAL-FACE Science Meeting at Salt Lake City, Feb. 2003

Chan, K. R., J. Dean-Day, S. W. Bowen, and T. P. Bui (1998), Turbulence measurements by the DC-8 meteorological measurement system, Geophys. Res. Lett., 25(9), 1355–1358.

Contact Information

The data provider is:

T. Paul Bui
NASA Ames Research Center

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