Langley DAAC Version Number:   LD_008_008_001_00_00_0_19990201


             48 Inch Lidar Aerosol Research Branch Readme

1.0  Introduction

This file contains information about the Aerosol Research Branch (ARB) 
Aerosol 48 inch Lidar sample read software and data files. Currently, 
there is one read software available. This data set is in ASCII format.
This readme file also includes the following five other sections:
        Section 2.0 - describes sample program (source file).
        Section 3.0 - discusses how to create the executable from the program.
        Section 4.0 - demonstrates how to invoke the run-time executable.
        Section 5.0 - provides general information on all of the data sets.
        Section 6.0 - provides more detailed implementation notes.

If users have questions while using the ARB sample read software, please contact 
the Langley DAAC User and Data Services office. 

EOSDIS Langley DAAC
Science, Users and Data Services Office
NASA Langley Research Center
Mail Code 157D
2 South Wright Street
Hampton, Virginia 23681-2199
U.S.A.

E-mail:     larc@eos.nasa.gov
Phone:      (757)864-8656
FAX:        (757)864-8807


2.0  Read Software File

The sample read program for the ARB 48 inch Aerosol Lidar data set is developed 
in the C language. The C program has been tested on Sun, SGI, Dec Alpha and HP 
UNIX-based workstations. All library functions in the C source code are tested 
for ANSI C conformance. The file and its purpose is listed as follows:

     read_arb_48lidar.c - reads ARB Aerosol 48 inch lidar data.


3.0  Creating Executable Files

To compile the program type:
	% cc -o read_arb_48lidar read_arb_48idar.c


4.0  Invoking Read Software

This section illustrates the invocation of the executable file. Section 4.1 
describes how to run the read program for the ARB data set. At this time, this 
read program is able to read ARB Aerosol 48 inch Lidar data. The executable 
prompts the user for the filename of the data set (including the pathname). 
To execute the program, type:

		% read_arb_48lidar

read_arb_48lidar will read the ASCII data and send the output to standard output. 
In this case, standard output is the screen.The program will then prompt the user 
to select which parameters to output to standard output.


5.0  Data Sets Information
The read program, read_arb_48lidar.c, is able to read ARB Aerosol 48 inch Lidar 
data set. There is one subsection describing this data set. Section 5.1 describes 
the ARB Aerosol 48 inch Lidar data set. The data set's information is obtained from 
text files or documents from the data producer. The high-level data set descriptions, 
the data files, the variables in the data files, and the contacts for data production 
are given under each data set. These questions/responses are collected under the 
NOTES ON DATA title.

5.1  ARB Aerosol 48 inch Lidar Data Set (ARB_48_IN_LIDAR)

This data set is written in ASCII. 

Each granule (each file) consists of one year of data. This is an on going data set. 
LONG NAME FOR DATA SET:    Aerosol Research Branch (ARB) 48 inch Lidar 
                           (ARB_48_IN_LIDAR)

FILE NAMING CONVENTION:    arb_48_in_lidar_yyyy where yyyy represents the year 
                           (ex. 1996). 

VARIABLES:                 There are four parameters of data that are provided 
                           for each day's of collected data. These parameters 
                           are integrated backscatter, height, scattering ratio,
                           and aerosol backscattering coefficient. There is only
                           one value for the integrated backscatter parameter. 
                           This value will automatically be provided for each 
                           day. Height, scattering ratio, and aerosol 
                           backscattering consist of many values. For every 
                           height value, there is a scattering ratio and 
                           aerosol backscattering values. The user is able to 
                           select the order he/she wants to output these 
                           parameters to the screen.

Parameter Name	Minimum Value	Maximum Value	Units
Integrated Backscatter	0.0	1.E-1 (or 0.1)	1/sr
Altitude	0.0	33.0	Kilometers
Scattering Ratio	-1000.0	1000.0	Unitless
Aerosol Scattering Coefficient	-1.E-1 (or -0.1)	1.E-1 (0.1)	1/(km-sr)

*NOTE:  1/sr is 1/steradian

NOTES ON DATA:            Each granule consists of many days of data. The 
                          number of days varies in each granule/file. The table 
                          listed below consists of the granules, the total 
                          number of days of data in each granule, and the 
                          actual dates.

                          There is a browse image that applies to each data 
                          granule/file.

                          9999.0 is the fill value for every parameter in this 
                          data set.

                          Dates are represented in the data files in mmddyy 
                          format where mm is the month, dd is the day, and yy 
                          is the year. There are times when the date is not in 
                          six digits. This is when the month is a value less 
                          than ten.

Granule Name	        Total Number of Days	Dates
------------            --------------------    -----
arb_48_in_lidar_1982	       14	        61482
		                                62382
		                                70182
		                                72182
	                                 	81982
	                                        90882
		                                91482
		                                92382
		                                100682
		                                102782
		                                111682
		                                112982
		                                120782
		                                121482
arb_48_in_lidar_1983	        26	        11383
		                                11883
		                                30283
		                                30383
		                                32283
		                                62283
		                                62383
		                                62683
		                                62783
		                                63083
		                                70783
		                                72683
		                                72783
		                                81583
		                                82583
		                                83083
		                                91983
		                                100383
		                                102783
		                                103183
		                                110883
		                                111783
		                                112183
		                                112983
		                                113083
		                                120783
arb_48_in_lidar_1984	         24	        20884
		                                22184
		                                30284
		                                30784
		                                31484
	                                        40284
		                                41184
		                                42584
		                                42684
		                                50984
		                                51684
		                                52484
		                                60484
		                                61184
		                                62584
		                                70984
		                                80784
		                                81584
		                                82184
		                                90684
		                                91984
		                                102984
		                                110884
		                                112984
arb_48_in_lidar_1985        	  12	        21085
		                                22085
		                                30685
		                                31285
		                                50685
		                                61385
		                                62085
		                                62685
		                                70985
		                                71885
		                                110785
		                                121085
arb_48_in_lidar_1986              21            21486
		                                30686
		                                42986
		                                43086
		                                50686
		                                51386
		                                60486
		                                61086
		                                61886
		                                62686
		                                82686
		                                91786
		                                101686
		                                102086
		                                102886
		                                102986
		                                111986
		                                112186 
		                                120386
		                                120486
		                                122286
arb_48_in_lidar_1987              23	        10887
		                                11487
		                                21387
		                                21987
		                                22087
		                                22687
		                                50187
		                                61187
		                                61987
		                                62687
		                                63087
		                                72287
		                                72487
		                                81287
		                                81887
		                                82587
		                                91687
		                                92587
		                                92987
		                                100587
		                                102287
		                                111387
		                                112387
arb_48_in_lidar_1988	          9	        30188
		                                32388
		                                32988
		                                81788
		                                82388
		                                91688
		                                92288
		                                92888
		                                102788
arb_48_in_lidar_1989	          6	        32889
		                                72589
		                                100489
		                                100589
		                                101289
		                                102189
arb_48_in_lidar_1990	          14	        13190
		                                20890
		                                21390
		                                22090
		                                22690
		                                22890
		                                30190
		                                32190
		                                32790
		                                42490
		                                60190
		                                110690
		                                111590
		                                112090
arb_48_in_lidar_1991	          33	        61491
		                                62891
		                                62991
		                                63091
		                                71491
		                                71891
		                                80391
		                                80491
		                                80691
		                                81691
		                                81791
		                                82291
		                                82891
		                                82991
		                                91791
		                                92191
		                                92791
		                                93091
		                                100191
		                                100791
		                                100991
		                                102291
		                                102491
		                                102991
		                                103091
		                                110591
		                                111391
		                                112091
		                                112591
		                                120491
		                                121091
		                                121691
		                                123191
arb_48_in_lidar_1992	          41	        10792
		                                11192
		                                11292
		                                11692
		                                12192
		                                12892
		                                20392
		                                21692
	                                        22092
		                                22892
		                                30292
		                                31192
		                                31692
		                                32392
		                                33192
	                                        41492
		                                42392
		                                43092
		                                50592
		                                51292
		                                52292
		                                61692
		                                62392
		                                63092
		                                71092
		                                71592
		                                72992
		                                81192
		                                82592
		                                90292
		                                90992
		                                91492
		                                91692
		                                91792
		                                100192
		                                100692
		                                101392
		                                101992
		                                110392
		                                110992
		                                111692
arb_48_in_lidar_1993	            21	        11793
		                                11993
		                                21993
		                                22493
		                                30293
		                                31093
		                                31693
		                                40493
		                                42993
		                                50793
		                                51193
		                                62393
		                                70993
		                                72293
		                                73093
		                                82493
		                                100693
		                                111093
		                                112993
		                                120693
		                                122293
arb_48_in_lidar_1994	            13	        10594
		                                12494
		                                21494
		                                22494
		                                32394
		                                40594
		                                51794
		                                62994
		                                80994
		                                92094
		                                93094
		                                111494
		                                112394

arb_48_in_lidar_1995                 5          32395
                                                 50495
                                                 102095
                                                 102495
                                                 120495



arb_48_in_lidar_1996                 9           42596
                                                 52196
                                                 53196
                                                 100496
                                                 101196
                                                 101696
                                                 102496
                                                 103196
                                                 120296

arb_48_in_lidar_1997                 15          11597
                                                 12297
                                                 22697
                                                 31397
                                                 32197
                                                 32597
                                                 40397
                                                 40897
                                                 41697
                                                 50797
                                                 52297
                                                 61197
                                                 71597
                                                 80197
                                                 90597

arb_48_in_lidar_1998                 13          22698
                                                 40398
                                                 40798
                                                 41398
                                                 52098
                                                 61998
                                                 70298
                                                 71498
                                                 91098
                                                 92498
                                                 101598
                                                 112498
                                                 120298




INSTRUMENTATION:
The lidar system used for the measurements presented in this report consists of a 
ruby laser, nominally emitting 1 joule per pulse at a repetition rate of 1 Hz at a 
wavelength () of 0.6943  m, and a 48-in. (1.22-m) cassegrainian configured telescope 
mounted on a mobile platform. The divergence of the transmitted laser beam is 
approximately 1.0 mrad, and the maximum receiver field of view is 4.0 mrad. The 
signal bandwidth of the lidar is 1 MHz, which is equivalent to a 150-m-altitude 
resolution. Three photomultiplier tubes, electronically switched on at specific 
times after laser firing, are used to enhance the dynamic range. The photomultiplier 
output signals are processed with an analog-to-digital converter and minicomputer, 
stored on magnetic tape, and displayed on an interactive terminal.

CONTACTS FOR DATA PRODUCTION INFORMATION:
Mary T. Osborn
Atmospheric Science Division - Aerosol Research Branch
23A Langley Boulevard
NASA Largely Research Center
Hampton, Virginia 23681-2199
Phone: (757) 864-2692
FAX: (757) 864-2671
E-Mail:   M.T.OSBORN@LaRC.NASA.GOV


6.0  Implementation Notes
The read_arb_48lidar.c program is able to read ARB Aerosol 48 Lidar data When 
executed, the program prompts the user for the filename. The program will then print 
out a list of the parameters that are included in the data set. All of the parameters
the user selects will be printed out for every day. Along with these parameters, the 
program will print out additional information such as the Date, the total number of 
altitudes, and the integrated backscattering value for each day. All output 
generated is written to the screen. Users can redirect the output to a file at the 
command line or modify the code to write the output to a file.
 
   *****************************************************
   *                                                   *
   *             ARB 48 inch Aerosol Lidar             *
   *                   Read Program                    *
   *                                                   *
   *                                                   *
   *  Version 2.0                     January 31, 1999 *
   *****************************************************

 
Please enter the input data file name. Include
the entire path. --> arb_48_in_lidar_1982
 
 
The filename for this input data file is arb_48_in_lidar_1982.
 
 
There are three parameters of information that were
collected at each event. These parameters are:
 
    No.      Parameter                                Units
    ---      ---------                                -----
     1.      Altitude                                Kilometers
     2.      Scattering Ratio                        Unitless
     3.      Aerosol Backscattering Coefficient      1/(km-sr)
 
 
Enter `a' or `A' to output all parameters in the above format.
Enter `x' or `X' to eXit this program.
Enter the total number of parameters to output (1-3). --> 3
 
 
Enter parameter number 1 --> 3
Enter parameter number 2 --> 1     
Enter parameter number 3 --> 2


DATE:  61482
Total number of Altitudes: 221 
Integrated Backscattered: 0.000774
 
9999.0000000000 0.000000 9999.000000 
9999.0000000000 0.150000 9999.000000 
9999.0000000000 0.300000 9999.000000 
9999.0000000000 0.450000 9999.000000 
9999.0000000000 0.600000 9999.000000 
9999.0000000000 0.750000 9999.000000 
9999.0000000000 0.900000 9999.000000 
9999.0000000000 1.050000 9999.000000 
9999.0000000000 1.200000 9999.000000 
9999.0000000000 1.350000 9999.000000 
9999.0000000000 1.500000 9999.000000 
9999.0000000000 1.650000 9999.000000 
9999.0000000000 1.800000 9999.000000 
9999.0000000000 1.950000 9999.000000 
9999.0000000000 2.100000 9999.000000 
9999.0000000000 2.250000 9999.000000 
9999.0000000000 2.400000 9999.000000 
9999.0000000000 2.550000 9999.000000 
9999.0000000000 2.700000 9999.000000 
9999.0000000000 2.850000 9999.000000 
9999.0000000000 3.000000 9999.000000 
9999.0000000000 3.150000 9999.000000 
9999.0000000000 3.300000 9999.000000 
9999.0000000000 3.450000 9999.000000 
9999.0000000000 3.600000 9999.000000 
9999.0000000000 3.750000 9999.000000 
9999.0000000000 3.900000 9999.000000 
0.0000209450 4.050000 1.060000 
0.0000176570 4.200000 1.051000 
0.0000110720 4.350000 1.033000 
0.0000071247 4.500000 1.021000 
0.0000122860 4.650000 1.037000 
0.0000214010 4.800000 1.066000 
0.0000334420 4.950000 1.105000 
0.0000455460 5.100000 1.145000 
0.0000465330 5.250000 1.150000 
0.0000326060 5.400000 1.107000 

...
...
...
0.0000073953 30.900000 2.115000 
0.0000067316 31.050000 2.039000 
0.0000062934 31.200000 1.995000 
0.0000060039 31.350000 1.973000 
0.0000052184 31.500000 1.866000 
0.0000047963 31.650000 1.815000 
0.0000049005 31.800000 1.853000 
0.0000047728 31.950000 1.851000 
0.0000046012 32.100000 1.841000 
0.0000044796 32.250000 1.840000 
0.0000042780 32.400000 1.823000 
0.0000041141 32.550000 1.811000 
0.0000040481 32.700000 1.819000 
0.0000039120 32.850000 1.811000 
0.0000038492 33.000000 1.819000



Updated:    February 1, 1999       LD_008_008_001_00_00_0_19990201
Last Updated:  February 1, 1999    LD_008_008_001_00_00_0_19990201
Last Updated:  July 20, 1999       LD_008_008_001_00_00_0_19990201