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 User and Data Services Office NASA Langley Research Center Mail Code 157D Hampton, Virginia 23681-2199 U.S.A. E-mail: support-asdc@earthdata.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 arb_48_in_lidar_1999 8 21199 22399 30599 41499 51199 52199 52899 92499 arb_48_in_lidar_2000 5 50900 90800 101200 102000 103000 arb_48_in_lidar_2001 9 22701 50101 52401 90701 100401 101601 110801 112201 120401 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 13, 2002 April 6, 2012 - email changed