LD_008_014_001_00_00_0_19990120 LITE Readme 1.0 Introduction This file contains information about the Lidar In-Space Technology Experiment (LITE) sample read software and data files. The LITE data set (LITE_L1) is available through the Langley Distributed Active Archive Center (DAAC). LITE is a three-wavelength backscatter lidar which flew on Discovery as part of the STS-64 mission between September 9 and September 20, 1994. Data were collected while airborne and ground-based lidars in North and South America, Europe, Asia and Australia provided correlative data. The LITE instrument was designed with the capability to make measurements of clouds, aerosols in the stratosphere and troposphere, the height of the planetary boundary layer, and atmospheric temperature and density in the stratosphere between 25 km and 40 km altitude. Additionally, limited measurements of the surface return strength over both land and ocean were collected to explore retrievals of surface properties. Data are in binary files and can be read with the DAAC-provided read software. Read software and additional information about the LITE data sets can be found at the Langley DAAC URL: http://eosweb.larc.nasa.gov NASA Langley's Atmospheric Sciences Division (ASD) has additional information about the LITE projct at: http://www-arb.larc.nasa.gov/lite The LITE web site contains additional read software, browse images, photos taken during data collection, and other information about the project. This Readme file includes four 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 set. If there are questions about using the LITE sample read software, please contact the Langley Science User and Data Services (SUDS) office at: Langley DAAC Science User and Data Services Office NASA Langley Research Center Mail Stop 157D, 2 S. Wright St. Hampton, VA 23681-2199 USA E-Mail: larc@eos.nasa.gov Telephone: (757)864-8656 FAX: (757)864-8807 2.0 Read Software Files Currently, there are two sample read programs which work with the LITE data set, L1read.c and L1scan.pro. L1read.c 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 SGI Origin 2000 IRIX 6.4 L1scan.pro is written in IDL (Research Systems Inc.) and has been tested in IDL version 5.1. There is nothing in the code however that should limit its use to slightly older versions of IDL. These programs are written as examples of how to read the LITE 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 readlite L1read.c 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 readlite. 3.2 Create IDL program First invoke IDL on your host computer and then type: IDL> .run L1scan.pro 4.0 Invoking Read Software 4.1 Running the executable version of the LITE Read C Program The executable version of the LITE read C program requires one command line argument, the name of the LITE data file, e.g. readlite LITE_L1_19940910_043646_043707 If the file is not in the directory where 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 LITE file is not specified at the command line when the program is executed, the program terminates and reminds you to include a filename. Here is a sample run: sorcerer 1: cc -o readlite L1read.c sorcerer 2: readlite LITE_L1_19940910_045307_045507 GMT Day: 253 Time: 04:53:07.22 355 532 1064 --------- --------- --------- -3.55 9.50 9999.00 8.45 15.51 9999.00 7.46 -0.49 9999.00 0.46 5.51 9999.00 -1.53 -9.49 9999.00 3.47 0.50 9999.00 14.48 4.50 9999.00 3.48 -1.51 9999.00 3.49 11.49 9999.00 -3.51 3.48 9999.00 -5.50 8.47 9999.00 -6.49 8.46 9999.00 1.52 -2.55 9999.00 5.52 14.44 9999.00 -9.47 -14.58 9999.00 2.54 4.41 9999.00 0.55 1.39 9999.00 . . . The output continues until all 3000 counts are printed for each wavelength. 4.2 Running the IDL version of the read software To run the IDL version of the read software you will need IDL installed on your host computer. The following is a sample session. darrin 1% idl IDL Version 5.0.2 (IRIX mipseb). Research Systems, Inc. IDL> .run L1scan.pro % Compiled module: L1SCAN. IDL> L1scan, 'LITE_L1_19940910_045307_045507' % Compiled module: JULDAY. % Compiled module: CALDAT. GranuleName: LITE_L1_19940910_045307_045507 GranuleSize: 33787500 Minlon: -42.9392 Maxlat: +31.9339 Maxlon: -37.7501 Minlat: +25.6285 Start Time: 04:53:07.22 End Time: 04:55:07.12 Start Date: 1994-09-10 End Date: 1994-09-10 IDL> 5.0 Data Set Information All granule names have the following form: LITE_L1_YYYYMMDD_HHMMSS_HHMMSS Where: LITE_L1 = LITE Level 1 data. YYYYMMDD = Year, Month, & Date of collection. HHMMSS = Hour, Minute, Second of the first data segment. HHMMSS = Hour, Minute, Second of the last data segment. Thus the granule name reveals the collection date and the start and end times of collection. For a complete description of the data set, please see the Data Format Description document which is available from the DAAC web site. It is available with the read software for the LITE data set. CONTACT FOR DATA PRODUCT INFORMATION: Kathleen A. Powell, Data Manager NASA Langley Research Center MS 475 Hampton VA 23681-0001 phone: (757) 864-2688 FAX: (757) 864-2671 e-mail: k.a.powell@larc.nasa.gov Document Creation Date: 1/12/1999