CAMEX-4 DC-8 Microwave Temperature Profiler (MTP)

Table of Contents

1. Introduction
2. Instrument description
3. Data Products and Format
4. Contact Information

1. Introduction

The fourth field campaign in the Convection and Moisture Experiment series (CAMEX-4) ran from 16 August to 25 September, 2001 and was based out of Jacksonville Naval Air Station, Florida. CAMEX-4 focused on the study of tropical cyclone (hurricane) development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation. The NASA DC-8 carried numerous instruments durnig the the experiment.

The Microwave Temperature Profiler (MTP) retrieves profiles of air temperature versus altitude along an aircraft flight track. It does this by measuring the natural thermal microwave emission from oxygen molecules in the earth’s atmosphere, and then performing a statistical retrieval inversion procedure. This retrieval is based on an archive of thousands of atmospheric soundings that results in the most likely temperature profile given the measurements. This retrieved profile is then displayed on monitors throughout the DC-8 and can be used for real time flight planning.

JPL, the instrument owner, has an outstanding web page that has detailed information about the instrument and remote microwave remote sensing in general. Additionally, there is provided an instrument history, photos and tools for use in data analysis. That web page is located at the Microwave Temperature Profiler web site, which links to an excellent tutorial about microwave temperature measurements.

2. Instrument Description

The DC-8 MTP is a passive microwave radiometer that measures the natural thermal emission from oxygen molecules at three frequencies (55.51, 56.66 and 58.79 GHz). The instrument views ten elevation angles between - 80 and +80 degrees by using a scanning mirror, located behind a microwave window on the sensor unit, to change the viewing direction. The sensor unit is located in a window just aft of the forward starboard exit door. The MTP retrieves profiles of air temperature versus altitude, which it displays on a dedicated color LCD display beside the Mission Manager's console. This signal is distributed to the ICATS monitors throughout the aircraft.

There is more information available about the instrument, installation and display available here.

3. Data Products and Format

Data are 'tarred' into daily (mission) data files of the form:

c4dmtp_2001.jjj_010mmm.tar

where c4dmtp represents CAMEX-4 and the DC-8 MTP instrument, 2001.jjj is the four digit year and day of year, 010mmm is the unique mission number.

When untarred, this will yield a datafile and an image file. File naming convention for the data file is:

MPyyyymmdd.DC8

where MP identifies the data as from the microwave profiler, yyyymmdd is the four digit year month and day of month. DC-8 advises that these data are from the DC-8 mounted instrument. The data is in ascii, with a large descriptive header. This header describes in detail the format of the data which follows. It is shown below:

59  2110
MJ MAHONEY (Michael.J.Mahoney@jpl.nasa.gov)
M/S 246-102; Jet Propulsion Laboratory; Pasadena, CA 91109-8099
DC-8 Microwave Temperature Profiler (MTP/DC8)
CAMEX-4
1 1
2001 08 25  2002 04 19  20010408 {FLT DATE, REDUCTION DATE & FLIGHT NUMBER}
0.0  0.0
Remote sensing altitude (meters)
Elapsed UT seconds from 0 hours on day given by DATE
4                         {NV = number of primary variables: temp, SEtemp, Zg, #density}
1.0   1.0    1.0 1E+21    {scale factors for primary variables: temp, SEtemp, Zg, #density}
99999 9999 99999 99999    {missing values for primary variables: temp, SEtemp, Zg, #density}
Retrieved air temperature (K)
Standard error of retrieved air temperture (K)
Geometric altitude (meters).
Molecular air density (number per cubic meter)
12             {number of auxiliary variables}
1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0
99 99.999 99.9 99.9 999.9 99.9 99.9 999.9 999.9 99.999 999.999 999.9
NX(1) is the number of altitudes in subsequent data records
Pressure altitude of DC-8 (km)
Aircraft pitch (deg)
Aircraft roll (deg)
Horizon brightness temperature (ie, OAT, similar to SAT); avg ch1, ch2 & ch3 (K)
Tropopause #1 (km).
Tropopause #2 (km).
Potential temperature of tropopause #1 (K).
Potential temperature of tropopause #2 (K).
Latitude (deg)
Longitude (deg)
dT/dz (K/km) for 1.0 km layer centered on aircraft flight altitude.
6              {number of special comment lines}
***  
*** 
*** 
*** 
*** 
*** 
19             {number of normally included comment lines}
Here's a brief free-form tutorial on how to decipher the MTP data: Data groups
   consist of the following group of lines per 15-second observing cycle.
First line is:  UTSEC, number of retrieval levels in following table, Pressure 
   Altitude, Pitch, Roll, Outside air temp (K), tropopause altitude #1 (km), 
   tropopause altitude #2 (km) [if present], potential temperatures of tropopause 
   #1 and #2, latitude, longitude, & lapse rate near flight level.  
   The 1-liners (for each cycle) can be stripped & imported into a spreadsheet 
   for convenient plotting of trop altitude, lapse rate, etc. The tropopause
   altitudes are calculated by cubic spline interpolation of the retrieved 
   altitudes using the WMO definition (that is, trop #1 is lowest altitude 
   where average lapse rate > -2 K/km from initial -2 K/km point to any point 
   within 2 km; trop #2 occurs above first trop after lapse rate is < -3K/km 
   for >1 km, and then first trop definition applies, possibly from within
   the 1 km region.)
Remaining set of lines for each cycle consist of 5 columns: col#1 is pressure 
   altitude (meters), col#2 is temperature from MTP (Kelvin), col#3 is temperature
   error estimate (K), col#4 is geometric altitude (meters), based on ICATS GPS 
   altitude (meters), and col#5 is molecular air density [1E+21/m3].

...
 61653  0  10.046   2.6 -34.8 231.7  99.9  99.9  99.9 999.9  28.115  -80.088  99.9
  61667  0  10.045   2.0 -28.2 231.7  99.9  99.9  99.9 999.9  28.095  -80.106  -7.6
  61681  0  10.045   2.8 -26.2 231.7  99.9  99.9  99.9 999.9  28.070  -80.111  -7.6
  61694  0  10.049   2.6 -25.4 231.5  99.9  99.9  99.9 999.9  28.045  -80.106  -7.6
  61708  0  10.048   2.7 -25.2 231.7  99.9  99.9  99.9 999.9  28.025  -80.096  -7.6
  61722  0  10.048   2.7 -24.0 231.7  99.9  99.9  99.9 999.9  28.006  -80.076  -7.6
  61736  0  10.049   2.9 -23.9 232.0  99.9  99.9  99.9 999.9  27.995  -80.053  -7.6
  61749  0  10.050   2.9 -24.3 232.2  99.9  99.9  99.9 999.9  27.990  -80.025  -7.6
  61763  0  10.049   2.9 -23.8 232.2  99.9  99.9  99.9 999.9  27.993  -80.000  -7.8
  61777  0  10.043   2.6 -14.2 232.2  99.9  99.9  99.9 999.9  28.001  -79.976  -8.0
  61791 33  10.040   2.5  -3.9 232.5  14.9  99.9 370.4 999.9  28.015  -79.955  -7.8
 28040 224.9 4.5 28289   507
 24550 219.7 4.1 24779   887
 21440 213.5 3.4 21709  1479
 19040 207.3 2.8 19379  2222
 16940 203.3 2.6 17379  3155
 15240 202.4 2.3 15779  4144
 14040 205.4 2.1 14649  4934
 13240 208.7 2.0 13879  5509
 12540 212.8 0.9 13199  6033
 12040 216.5 0.9 12699  6418
 11640 219.5 0.8 12289  6741
 11340 221.9 0.8 11989  6994
 11040 224.1 0.7 11679  7258
 10740 226.5 0.7 11359  7528
 10540 228.2 0.7 11159  7711
 10340 229.7 0.6 10949  7900
 10190 230.9 0.6 10789  8043
 10040 232.1 0.6 10629  8189
  9890 233.3 0.6 10479  8336
  9740 234.4 0.6 10319  8488
  9540 236.0 0.7 10109  8691
  9340 237.6 0.7  9899  8896
  9040 240.1 0.7  9589  9207
  8740 242.6 0.7  9269  9528
  8440 245.1 0.8  8949  9856
  8040 248.3 0.8  8529 10312
  7540 252.1 0.9  7999 10916
  6840 257.0 0.9  7259 11827
  6040 262.6 2.1  6409 12934
  4940 269.6 2.6  5249 14630
  3540 278.4 3.2  3769 17041
  2040 286.7 4.1  2189 20053
   540 296.5 4.8   599 23419
...

 

TZS_2001mmdd.gif

is the file name for the image file that may be viewed with almost any image viewer and an example appears below:

4. Contact Information

Data can be ordered and questions addressed at http://ghrc.nsstc.nasa.gov/.

To order this 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: ghrc@eos.nasa.gov

[NASA logo] NASA Information Contact: Michael Goodman, Global Hydrology and Climate Center
GHRC Web Curator: GHRC Web Team
Last update: Tuesday, 12-Jun-2007 17:36:38 CDT
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