FIRE_AX_CMS_LWFLUX Readme 1.0 Introduction This file contains information about the First ISCCP Regional Experiment (FIRE) Atlantic Stratocumulus Transition Experiment (ASTEX) Centre de Meteorologie Spatiale (CMS) Longwave Flux "readme" files includes the following five other sections: * Section 2.0 - describes the "C" program (source file) * Section 3.0 - describes how to create the executable from the "C" program. * Section 4.0 - demonstrates how to invoke the run-time executable. * Section 5.0 - provides general information on the data sets. * Section 6.0 - provides more detailed implementation notes. If users have questions while using the FIRE_AX_CMS_LWFLUX sample read software, please contact the Langley Science, User, and Data Support office. They may be reached by e-mail at larc@eos.nasa.gov, by telephone at (757) 864-8656, by FAX at (757) 864-8807, or by mail at: Langley DAAC Science, User, and Data Support Office NASA Langley Research Center Mail Stop 157D Hampton, VA 23681-0001 2.0 Read Software Files The read program was developed in the "C" language. This program has been tested on the "Sun4", and the "HP" UNIX based workstations. There are no library routines that need to be loaded or linked. A "Makefile" is included for the convenience of creating the executable file from the source file. These files and their purposes are listed as follows: Makefile.fax - contains a set of commands to build the run-time executable fire_ax_cms_lwflux.c - reads the data 3.0 Creating C Executable Files The user has two ways of building the sample read program from the source file. One is applying the "make" command to the file "Makefile.fax", which defines the "C" source file listed in Section 2.0. The other is using the "C" compiler "cc" (or 'acc' for ANSI 'C' compiler). Section 3.1 illustrates the first method, and Section 3.2 illustrates the second method. The first method is simpler to use than the second one. The symbol '%' in this section stands for UNIX command line prompt. 3.1 Create with 'make' command: %make -f Makefile.fax cmslwflux 3.2 Create with C compiler 'cc': To use the command line to compile the CMS_LWFLUX read software type: %cc -o cmslwflux fire_ax_cms_lwflux.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 FIRE_AX_CMS_LWFLUX data set. 4.1 Running the Read Program for the FIRE_AX_CMS_LWFLUX Data Set When this program is executed, it displays a banner page with the information pertaining to the Langley DAAC. The program then prompts for a name of a good data file to read. The output by default prints to the screen. The output can be saved to a file by using redirection. cmslwflux > out_file NOTE: if you do this the program will not display anything to the screen so type the input file name in like you would do if you were prompted for it. For example, % cmslwflux > out_file data filename (i.e., ra310592s01.fis) 1) cmslwflux -- this is the executable from Section 3.0. 2) out_file -- this is any file you wish to write output to. 5.0 Data Set Information The FIRE_AX_CMS_LWFLUX data set contains METEOSAT observations that give calculated downward longwave flux at the surface data. The file naming convention is: raDDMMYYsxx.fis Where DDMMYY is the date and xx = "slot number" Mean time (UT) is obtained from the slot number over the ASTEX region by the formula: UT = (xx/2) - 0.17 These files are: I2 pixels, 188 pixels/row, 163 rows. Each pixel has a spatial resolution of 0.08 degrees. The units of flux are Wm^-2. For longwave flux, the rule is the following: latitude = 39.99 - ((row - 1) * 0.08) and the longitude = 29.97 + ((data point - 1) * 0.08) (longitude west is < 0). This gives you the latitude and longitude of any pixel of the file which contains 188 points and 163 rows. 5.1 Notes On Data FIRST RECORD OF DATA FROM FIRST DATA GRANULE: -------------------------------------------- Now do the processing for row 1 Latitude : 39.99 These are the data values from the file pixel count LONGWAVE_FLUX Longitude in the data for row 1 Wm^-2 ------------------------------------------------------------------------------------------------------- 1 3753 -29.97 2 3750 -29.89 3 3750 -29.81 4 3749 -29.73 5 3749 -29.65 6 3746 -29.57 7 3746 -29.49 8 3745 -29.41 9 3745 -29.33 10 3745 -29.25 11 3742 -29.17 12 3742 -29.09 13 3740 -29.01 14 3740 -28.93 15 3738 -28.85 16 3738 -28.77 17 3736 -28.69 18 3736 -28.61 19 3733 -28.53 20 3733 -28.45 21 3731 -28.37 22 3731 -28.29 23 3727 -28.21 24 3727 -28.13 25 3728 -28.05 26 3728 -27.97 27 3729 -27.89 28 3729 -27.81 29 3730 -27.73 30 3730 -27.65 31 3731 -27.57 32 3731 -27.49 33 3731 -27.41 34 3731 -27.33 35 3732 -27.25 36 3732 -27.17 37 3732 -27.09 38 3733 -27.01 39 3733 -26.93 40 3734 -26.85 41 3734 -26.77 42 3734 -26.69 43 3734 -26.61 44 3735 -26.53 45 3735 -26.45 46 3736 -26.37 47 3736 -26.29 48 3736 -26.21 49 3736 -26.13 50 3738 -26.05 51 3738 -25.97 52 3740 -25.89 53 3740 -25.81 54 3742 -25.73 55 3742 -25.65 56 3744 -25.57 57 3744 -25.49 58 3747 -25.41 59 3747 -25.33 60 3747 -25.25 61 3750 -25.17 62 3750 -25.09 63 3752 -25.01 64 3752 -24.93 65 3754 -24.85 66 3754 -24.77 67 3756 -24.69 68 3756 -24.61 69 3759 -24.53 70 3759 -24.45 71 3761 -24.37 72 3761 -24.29 73 3765 -24.21 74 3765 -24.13 75 3764 -24.05 76 3764 -23.97 77 3763 -23.89 78 3763 -23.81 79 3761 -23.73 80 3761 -23.65 81 3761 -23.57 82 3761 -23.49 83 3759 -23.41 84 3759 -23.33 85 3759 -23.25 86 3758 -23.17 87 3758 -23.09 88 3757 -23.01 89 3757 -22.93 90 3755 -22.85 91 3755 -22.77 92 3754 -22.69 93 3754 -22.61 94 3753 -22.53 95 3753 -22.45 96 3752 -22.37 97 3752 -22.29 98 3751 -22.21 99 3751 -22.13 100 3749 -22.05 101 3749 -21.97 102 3747 -21.89 103 3747 -21.81 104 3745 -21.73 105 3656 -21.65 106 3655 -21.57 107 3655 -21.49 108 3653 -21.41 109 3653 -21.33 110 3653 -21.25 111 3740 -21.17 112 3740 -21.09 113 3738 -21.01 114 3738 -20.93 115 3736 -20.85 116 3736 -20.77 117 3735 -20.69 118 3647 -20.61 119 3520 -20.53 120 3410 -20.45 121 3642 -20.37 122 3642 -20.29 123 3640 -20.21 124 3640 -20.13 125 3725 -20.05 126 3725 -19.97 127 3723 -19.89 128 3723 -19.81 129 3720 -19.73 130 3720 -19.65 131 3718 -19.57 132 3718 -19.49 133 3716 -19.41 134 3716 -19.33 135 3714 -19.25 136 3714 -19.17 137 3714 -19.09 138 3714 -19.01 139 3714 -18.93 140 3713 -18.85 141 3713 -18.77 142 3713 -18.69 143 3713 -18.61 144 3713 -18.53 145 3628 -18.45 146 3629 -18.37 147 3629 -18.29 148 3631 -18.21 149 3631 -18.13 150 3631 -18.05 151 3716 -17.97 152 3716 -17.89 153 3716 -17.81 154 3629 -17.73 155 3714 -17.65 156 3716 -17.57 157 3716 -17.49 158 3718 -17.41 159 3718 -17.33 160 3636 -17.25 161 3636 -17.17 162 3635 -17.09 163 3749 -17.01 164 3721 -16.93 165 3720 -16.85 166 3720 -16.77 167 3718 -16.69 168 3718 -16.61 169 3721 -16.53 170 3721 -16.45 171 3724 -16.37 172 3753 -16.29 173 3728 -16.21 174 3757 -16.13 175 3730 -16.05 176 3730 -15.97 177 3760 -15.89 178 3760 -15.81 179 3733 -15.73 180 3647 -15.65 181 3525 -15.57 182 3525 -15.49 183 3526 -15.41 184 3526 -15.33 185 3418 -15.25 186 3419 -15.17 187 3732 -15.09 188 3753 -15.01 6.0 Implementation Notes This interactive read program first expects to read data from a data file. The program reads the data, decodes it and prints out the flux values. All the 163 rows are printed out. APPENDIX A-1: Output from running "make" on "HP" workstation. HP% make -f Makefile.fax cmslwflux cc -g -I/usr/local/hdf-3.3r4/hdf/include -o cmslwflux fire_ax_cms_lwflux.c A-2: Output from running "make" on SUN4 workstation: SUNOS% make -f Makefile.fax cmslwflux cc -g -DSUNOS -sun4 -DNO_HAVE_PROTOTYPES -DNO_STDARG -o cmslwflux fire_ax_cms_lwflux.c