LASE_SGP97 Readme

1.0  Introduction

This file contains information about the Lidar Atmospheric Sensing 
Experiment (LASE) SGP97 sample read software and data files.

The LASE_SGP97 data set includes two types of files, one containing 
atmospheric scattering ratio profiles and the other containing water vapor
concentration profiles.

The LASE SGP97 data files are stored in ASCII using the Global Tropospheric
Experiment (GTE) Data Archive Format and can be read with the
DAAC-provided read software.

Additional information about the LASE data sets can be found in the LASE
project and data set Guide documents at the Langley DAAC:

	http://eosweb.larc.nasa.gov
	
Images of data from the LASE data files can be viewed at the following
web site:
         
LASE_SGP97: 	 http://asd-www.larc.nasa.gov/lidar/sgp97/sgp97.html

Information about the LASE project and instrumentation can be found at

	http://asd-www.larc.nasa.gov/lase/ASDlase.html
	

Information about the Southern Great Plains experiment is available at

	http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/SGP97/sgp97.html
		
	
A document describing the GTE Data Archive Format is available from the
DAAC at:

	http://warlock.larc.nasa.gov/GUIDE/dataset_documents/pwb-fmat.html
	

This Readme file includes five other sections:

	Section 2.0 - describes the available read software.
	Section 3.0 - discusses how to create an executable program 
	              from read software source code.
	Section 4.0 - demonstrates how to invoke the executable program.
	Section 5.0 - provides general information for the data sets.
	Section 6.0 - provides more detailed implementation notes.
	
If there are questions about using the LASE sample read software, please 
contact the Langley Science, User and Data Services (SUDS) office. The SUDS
office may be reached by E-Mail: larc@eos.nasa.gov, by telephone at
(757)864-8656,  or  by FAX at (757)864-8807. The SUDS mailing address is:

	Langley DAAC Science, User and Data Services Office
	NASA Langley Research Center
	Mail Stop 157D, 2 S. Wright St.
	Hampton, VA 23681-2199
	USA
	
2.0  Read Software Files

Currently, there is one sample read program which works with all GTE-formatted 
LASE data sets, read_lase_gte.c.  It is written in ANSI C. This program has been 
tested on the following computers and operating systems:

	Computer		Operating System
	-------------------  	----------------
	Sun Sparc		Solaris 2.5
	Sun4			SunOS 4.1.3
	SGI Origin 2000		IRIX 6.4
	HP 9000/735		HP-UX 10.10
	DEC Alpha		Digital UNIX 4.0A
	
This program is written as an example of how to read in the LASE_SGP97 data.
As delivered, it reads in and writes to the screen the file header 
information followed by each profile's header and data.

3.0  Creating Executable Program Files

3.1  Create with C compiler

To compile the program, use the command for the ANSI C compiler.  The
command varies slightly among operating systems.  On Sun Solaris, SGI 
and DEC Alpha systems the command is:

	% cc  -o read_lase_gte read_lase_gte.c
	
On SunOS systems, use acc in place of cc in the preceding example.  On
HP-UX systems, the appropriate compiler command is c89 rather than cc.
If the appropriate compile command is not found on your system, check
to be sure that your PATH environment variable includes the directory
that contains the compiler or specify the entire path to the compiler
in your command.

This compile command creates an executable program file named read_lase_gte.

4.0  Invoking Read Software

4.1  Running the executable version of the LASE Read C Program

The executable version of the LASE read C program optionally accepts one 
command line argument, the name of the LASE data file, e.g.

	read_lase_gte lase_sgp97_aer_20

If the file is not in the directory from which the program is invoked, it 
is necessary to specify the full directory path to the data file along 
with its name.  The program allows for file names up to 50 characters
long.  If you have renamed the file to a longer name (including the
path), you can extend the maximum allowed length by changing the value 
assigned to the parameter MAX_FILENAME in the #define statement near the
beginning of the source code file.  Note that the value specified 
should be the maximum length needed + 1.

If the name of the LASE file is not specified at the command line when the 
program is executed, the user is prompted by the program to enter the file 
name.
				
A sample of the interactive program execution is provided in Section 6.0.

5.0  Data Set Information

5.1  LASE_SGP97 Data Set

LONG NAME FOR THIS DATA SET:

Lidar Atmospheric Sensing Experiment Southern Great Plains 1997 Experiment

FILE NAMING CONVENTION:

LASE_SGP97 data set files are prefixed with "lase_sgp97_" to indicate
they belong to this data set. This is followed by a three character designation 
of the type of profile stored in the file, 'aer' for atmospheric scattering
ratio data and 'h2o' for water vapor concentration.  The last two characters 
are digits indicating the flight number, preceded by an underscore.  Here
are two example file names:

	lase_sgp97_aer_20	atmospheric scattering ratio profiles from 
				flight 20 (the first LASE flight) of the 
				1997 SGP experiment

	lase_sgp97_h2o_22  	water vapor concentration profiles from 
				flight 22 of the LASE SGP 97 experiment

VARIABLES:

There are nine variables for each profile.  These variables are listed in
the file header along with information about each variable, including the
units, scale factor and offset, minimum and maximum values and the value
used to indicate missing data.  The last piece of information for each
variable in the GTE format is the Limits of Detection code.  That code is
not used in the LASE data and its value is set to 0.  Here's an example of
the variable definition section of the file header:

Day of Year,  Julian,  1.00000,  0,  252,  252,  -999.000,  0
Elapsed Time ,  Sec (UT) ,  1.00000,  0,  483,  12191,  -999.000,  0
Geo. Alt. of Aircraft ,  m ,  1.00000,  0,  19468,  19937,  -999.000,  0
Geo. Alt. @ Begn ,  m ,  1.00000,  0,  30,  2429,  -999.000,  0
Alt. increment ,  m ,  1.00000,  0,  30,  30,  -999.000,  0
Latitude ,  Deg N ,  0.0100000,  0,  3498,  3802,  -99900.0,  0
Longitude ,  Deg E ,  0.0100000,  0,  -8085,  -7478,  -99900.0,  0
Num Points in Profile,  ,  1.00000,  0,  419,  498,  -999.000,  0
Data Profile,  ,  0.0100000,  0,  -41707,  32697104,  -99900.0,  0

All values are stored in the file as integers; they should be multiplied
by the scale factor and then added to the offset value in order to be of
the proper magnitude.  This calculation is done in the sample read
software for those variables whose scale factor is not 1.0.  Note that
for all LASE variables the offset is 0.

The first eight variables are written out on one line at the beginning
of each profile, followed by the profile values, eight per line.  The 
abbreviation 'Geo. Alt.' stands for geopotential altitude, and 
'Geo. Alt. @ Begn' is the geopotential altitude at the beginning of the 
profile data array.
	

FIRST RECORD OF DATA FROM FIRST DATA FILE:

File header and first full profile from the lase_sgp97_aer_20 file.  Note
that the first full profile is preceded by several profiles with 0 data
points.

 26
sgp20s.arc
Browell, Dr. Edward V., NASA Langley Research Center
LASE / P-3 Aerosol Total Scattering Ratio Profiles
Southern Great Plains
97 07 11 98 07 22
20
 9
 5
3
0
3
Day of Year,  Julian,  1.00000,  0,  192,  192,  -999.000,  0
Elapsed Time ,  Sec (UT) ,  1.00000,  0,  54630,  60057,  -999.000,  0
Geo. Alt. of Aircraft ,  m ,  1.00000,  0,  8056,  8067,  -999.000,  0
Geo. Alt. @ Begn ,  m ,  1.00000,  0,  50,  472,  -999.000,  0
Alt. increment ,  m ,  1.00000,  0,  30,  30,  -999.000,  0
Latitude ,  Deg N ,  0.0100000,  0,  3433,  3637,  -99900.0,  0
Longitude ,  Deg E ,  0.0100000,  0,  -9836,  -9754,  -99900.0,  0
Num Points in Profile,  ,  1.00000,  0,  0,  247,  -999.000,  0
Data Profile,  ,  0.0100000,  0,  -741,  313232,  -99900.0,  0
--------------------------------------------------------------------
More information including data resolution and images are available 
via WWW at http://asd-www.larc.nasa.gov/lidar/lidar.html or contact 
Dr. Edward V. Browell (757)864-1273 (Head, Lidar Applications Group)
--------------------------------------------------------------------
 192,  54630,  8059,  -999,  30,  3566,  -9800,  0
 192,  54633,  8059,  -999,  30,  3565,  -9801,  0
 192,  54636,  8060,  -999,  30,  3565,  -9801,  0
 192,  54639,  8061,  -999,  30,  3564,  -9801,  0
 192,  54642,  8059,  -999,  30,  3563,  -9801,  0
 192,  54645,  8060,  -999,  30,  3563,  -9801,  0
 192,  54648,  8059,  -999,  30,  3563,  -9802,  0
 192,  54651,  8063,  -999,  30,  3562,  -9802,  0
 192,  54654,  8061,  -999,  30,  3562,  -9802,  0
 192,  54657,  8063,  -999,  30,  3562,  -9802,  0
 192,  54660,  8062,  -999,  30,  3561,  -9802,  0
 192,  54663,  8064,  -999,  30,  3561,  -9802,  0
 192,  54666,  8063,  -999,  30,  3560,  -9802,  0
 192,  54669,  8062,  -999,  30,  3560,  -9802,  0
 192,  54672,  8063,  -999,  30,  3560,  -9802,  0
 192,  54675,  8063,  -999,  30,  3559,  -9803,  0
 192,  54678,  8063,  -999,  30,  3559,  -9803,  0
 192,  54681,  8060,  -999,  30,  3558,  -9803,  0
 192,  54684,  8063,  -999,  30,  3558,  -9803,  0
 192,  54687,  8062,  -999,  30,  3557,  -9803,  0
 192,  54690,  8064,  -999,  30,  3557,  -9803,  0
 192,  54693,  8061,  -999,  30,  3556,  -9803,  0
 192,  54696,  8061,  -999,  30,  3556,  -9803,  0
 192,  54699,  8062,  -999,  30,  3556,  -9803,  0
 192,  54702,  8061,  -999,  30,  3555,  -9804,  0
 192,  54705,  8062,  -999,  30,  3555,  -9804,  0
 192,  54708,  8061,  -999,  30,  3554,  -9804,  0
 192,  54711,  8062,  -999,  30,  3554,  -9804,  0
 192,  54714,  8062,  -999,  30,  3554,  -9804,  0
 192,  54717,  8061,  -999,  30,  3553,  -9804,  0
 192,  54720,  8061,  -999,  30,  3552,  -9804,  0
 192,  54723,  8062,  -999,  30,  3552,  -9804,  0
 192,  54726,  8062,  -999,  30,  3552,  -9804,  0
 192,  54729,  8061,  -999,  30,  3551,  -9805,  0
 192,  54732,  8062,  -999,  30,  3551,  -9805,  0
 192,  54735,  8062,  -999,  30,  3550,  -9805,  0
 192,  54738,  8064,  -999,  30,  3550,  -9805,  0
 192,  54741,  8063,  -999,  30,  3550,  -9805,  0
 192,  54744,  8061,  -999,  30,  3549,  -9805,  0
 192,  54747,  8063,  -999,  30,  3549,  -9805,  0
 192,  54750,  8060,  -999,  30,  3548,  -9805,  0
 192,  54753,  8062,  450,  30,  3548,  -9805,  234
     330,     360,     375,     398,     427,     466,     536,     633,
     751,     933,    1138,    1127,     808,     528,     395,     364,
     345,     340,     345,     358,     358,     368,     402,     413,
     443,     489,     523,     537,     481,     399,     381,     401,
     413,     414,     412,     424,     432,     459,     470,     474,
     491,     503,     526,     550,     544,     523,     521,     556,
     595,     640,     734,     839,     909,     929,     954,    1014,
    1290,    1766,    2413,    2274,    1849,    1467,    1240,     832,
     578,     683,     635,     656,     703,     762,    1117,    2275,
    4156,    4715,    2107,    1186,     635,     607,     604,     806,
    1009,     932,    2951,    8977,    3276,    4220,    3438,    1154,
     705,     404,     362,     364,     349,     332,     327,     319,
     305,     318,     347,     331,     286,     237,     234,     220,
     189,     176,     174,     175,     176,     174,     180,     183,
     178,     162,     164,     169,     152,     147,     158,     159,
     157,     159,     164,     176,     190,     199,     186,     177,
     193,     207,     211,     217,     223,     218,     213,     212,
     220,     223,     220,     197,     172,     141,     125,     126,
     134,     146,     164,     196,     198,     176,     147,     130,
     121,     119,     119,     135,     160,     148,     129,     117,
     117,     124,     129,     131,     130,     131,     131,     134,
     135,     135,     136,     133,     133,     133,     129,     124,
     123,     123,     120,     116,     109,     102,     101,     102,
     100,     102,     105,     108,     111,     113,     115,     117,
     115,     107,     102,     102,     104,     106,     109,     114,
     127,     136,     139,     146,     150,     151,     146,     132,
     121,     113,     112,     113,     118,     129,     135,     133,
     133,     123,     122,     125,     123,     124,     132,     150,
     151,     144,     141,     146,     145,     144,     144,     144,
     144,     143 
      
CONTACTS FOR DATA PRODUCT INFORMATION:

	Vince Brackett
	NASA Langley Research Center
	MS 401A, 21 Langley Boulevard
	Hampton, VA  23681-1379
	USA
	E-mail:  v.g.brackett@larc.nasa.gov
	Phone:   757-864-5854
	Fax:     757-864-7790
	
	Marian B. Clayton
	NASA Langley Research Center
	MS 401A, 21 Langley Boulevard
	Hampton, VA  23681-1379
	USA
	E-mail:  m.b.clayton@larc.nasa.gov
	Phone:	 757-864-2841
	Fax:	 757-864-7790




6.0  Implementation Notes

This section gives a brief explanation of how to run the sample read software.

6.1  read_lase_gte C Program

The read_lase_gte C program can be used to read any of the LASE data set files.
The following is a sample session showing compilation and execution of the 
read_lase program on the machine named darrin.
 
darrin 3% cc -o read_lase_gte read_lase_gte.c
darrin 4% read_lase_gte
**********************************************************

                LASE READ PROGRAM 

  Version 2.0                               17 FEB 2000 

  This program reads the LASE data in the GTE Data Archive 
  Format. The input file name is built according to the  
  naming convention formed by the Langley DAAC.  Currently 
  the input file name is expected to be no more than 50 characters 
  in length. If you have changed the name of the 
  input file to greater than 50 characters, you will need to 
  modify this program, changing the value of the MAX_FILENAME 
  parameter in the #define statement near the beginning of the file
  to be at least the maximum length needed + 1.

  All data files are assumed to be in the current working directory. 
  If the files are located in another directory, please be sure 
  to include the complete path with the file name.


 Platforms tested:    SUN (Solaris 2.5 and SunOS 4.1.3) 
                      HP (HP-UX 10.10) 
                      SGI (IRIX 6.4) 
                      Dec Alpha (Digital UNIX V4.0A)
 

  Contact: Langley DAAC User and Data Services Office 
           NASA Langley Research Center 
           Mail Stop 157D 
           Hampton, VA 23681-2199 
           Phone (757)864-8656   Fax (757)864-8807 
           e-mail:  larc@eos.nasa.gov 
           http://eosweb.larc.nasa.gov 
**********************************************************


 Press Return or Enter to continue

Please enter the LASE data file name

lase_sgp97_aer_20

Investigator: Browell, Dr. Edward V., NASA Langley Research Center
Data: LASE / P-3 Aerosol Total Scattering Ratio Profiles
Mission: Southern Great Plains
Start date: 7/11/97 
Date processed: 7/22/98 
Flight Number: 20

Num  Variable                 Units       Scale    Offset  Min     Max   Missing
--------------------------------------------------------------------------------
 1)  Day of Year              Julian       1.00     0.00    192.00    192.00   -999.00 
 2)  Elapsed Time             Sec (UT)     1.00     0.00  54630.00  60057.00   -999.00 
 3)  Geo. Alt. of Aircraft    m            1.00     0.00   8056.00   8067.00   -999.00 
 4)  Geo. Alt. @ Begn         m            1.00     0.00     50.00    472.00   -999.00 
 5)  Alt. increment           m            1.00     0.00     30.00     30.00   -999.00 
 6)  Latitude                 Deg N        0.01     0.00   3433.00   3637.00 -99900.00 
 7)  Longitude                Deg E        0.01     0.00  -9836.00  -9754.00 -99900.00 
 8)  Num Points in Profile                 1.00     0.00      0.00    247.00   -999.00 
 9)  Data Profile                          0.01     0.00   -741.00 313232.00 -99900.00 


--------------------------------------------------------------------

More information including data resolution and images are available 

via WWW at http://asd-www.larc.nasa.gov/lidar/lidar.html or contact 

Dr. Edward V. Browell (757)864-1273 (Head, Lidar Applications Group)

--------------------------------------------------------------------

This program as delivered will write all the profiles
to the screen until the end-of-file is reached.

To interrupt the program use CTRL C (press the C key
while holding down the Ctrl or Control key).

Press Return or Enter to continue

Profile 1:
Day: 192   Time: 54630   Lat: 35.660000   Lon: -98.000000 
Altitude info--Aircraft: 8059 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 2:
Day: 192   Time: 54633   Lat: 35.649998   Lon: -98.009995 
Altitude info--Aircraft: 8059 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 3:
Day: 192   Time: 54636   Lat: 35.649998   Lon: -98.009995 
Altitude info--Aircraft: 8060 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 4:
Day: 192   Time: 54639   Lat: 35.639999   Lon: -98.009995 
Altitude info--Aircraft: 8061 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 5:
Day: 192   Time: 54642   Lat: 35.630001   Lon: -98.009995 
Altitude info--Aircraft: 8059 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 6:
Day: 192   Time: 54645   Lat: 35.630001   Lon: -98.009995 
Altitude info--Aircraft: 8060 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 7:
Day: 192   Time: 54648   Lat: 35.630001   Lon: -98.019997 
Altitude info--Aircraft: 8059 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 8:
Day: 192   Time: 54651   Lat: 35.619999   Lon: -98.019997 
Altitude info--Aircraft: 8063 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 9:
Day: 192   Time: 54654   Lat: 35.619999   Lon: -98.019997 
Altitude info--Aircraft: 8061 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 10:
Day: 192   Time: 54657   Lat: 35.619999   Lon: -98.019997 
Altitude info--Aircraft: 8063 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 11:
Day: 192   Time: 54660   Lat: 35.610001   Lon: -98.019997 
Altitude info--Aircraft: 8062 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 12:
Day: 192   Time: 54663   Lat: 35.610001   Lon: -98.019997 
Altitude info--Aircraft: 8064 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):


Profile 13:
Day: 192   Time: 54666   Lat: 35.599998   Lon: -98.019997 
Altitude info--Aircraft: 8063 @Begn:  -999  Increment: 30
Total Scattering Ratio Profile (  0 points):
.
.
.
 
Output of profiles continues until the end-of-file is reached or a CTRL-C
is entered (hold down the Control or CTRL key and press the C key).
 
 
----------------------------------
Last Modified 02-22-2000