________________________________________________________________________ Absorbing Aerosol Index and residues from Envisat/SCIAMACHY ________________________________________________________________________ The following datasets are available: ../daily/data/20YY/YYMMDD.tar.gz, containing: YYMMDD.esr ASCII file with gridded daily Envisat/SCIAMACHY residues from year 20YY, month MM, and day DD. The data in this ASCII file are in the format lon: 288 bins centered on 179.375 W to 179.375 E (1.25 degree steps); lat: 180 bins centered on 89.5 S to 89.5 N (1.00 degree steps), which is similar to the format used for the GOME AAI and the TOMS Nimbus-7 and Meteor-3 CD-ROM. Details of this format are explained in the EarthProbe Data Products User's Guide, "EARTHPROBE_USERGUIDE.PDF". The values are stored in 3-digit groups 111222333444. The numbers have been multiplied by 10 and 450 has been added. A value of 999 is used for missing, bad, or flagged data. 449 = -0.1 450 = 0.0 451 = 0.1 999 = missing, bad, or flagged data. ------------------------------------------------------------------------ YYMMDD.n Number of values used for gridding in a box. Format similar to that of daily residue files, but numbers are not manipulated. The values are stored in 3-digit groups 111222333444. ------------------------------------------------------------------------ ../monthly/data/YYMM.tar.gz, containing: YYMM.esa ASCII file with gridded monthly averaged Envisat/SCIAMACHY AAI from year 20YY and month MM. Format same as for daily residues. The values are stored in 3-digit groups 111222333444. The numbers have been multiplied by 10. A value of 999 is used for missing, bad, or flagged data, or to indicate that the AAI is not defined. 1 = 0.1 100 = 10.0 998 = 99.8 999 = missing, bad, or flagged data, or AAI not defined. ------------------------------------------------------------------------ YYMM.n Number of values used for gridding in a box. Format similar to that of monthly AAI files, but numbers are not manipulated. The values are stored in 3-digit groups 111222333444. ------------------------------------------------------------------------ ../daily/lv2data/20YY/YYMMDD_scia_aai.tar.gz, containing: YYMMDD_HHMM_scia_sc.aai ASCII files with Envisat/SCIAMACHY level-2 residue data for each of the orbits from year 20YY, month MM, and day DD. The HH and MM relate to the time of first measurement of the particular orbit. Residue, time, and geolocation information are given in the files. A tool to extract the data in IDL exists and can be downloaded. ________________________________________________________________________ Some tools are available for handling and plotting the data in IDL: ../tools/readbin.pro READBIN, FILE, DATA, TITLE This procedure will read the data in the format described above from file FILE and return the 288 x 180 integer array DATA. TITLE is the string containing the text of the first line of the file. ------------------------------------------------------------------------ ../tools/writebin.pro WRITEBIN, FILE, DATA, TITLE This procedure will store the data inside the 288 x 180 integer array DATA into the file FILE in the format described above. TITLE is the string containing the text of the first line of the file. ------------------------------------------------------------------------ ../tools/read_aai_level2.pro READ_AAI_LEVEL2 This procedure will read level-2 AAI data. See the source code for the calling sequence and the list of returned parameters. ------------------------------------------------------------------------ ../tools/plot_bin.pro PLOT_BIN This procedure will plot the data in the format described above from a selected file onto the world map. Uses readbin.pro. Type PLOT_BIN, /HELP for more info on available keywords. ________________________________________________________________________ The following image files are available: ../daily/images/20YY/YYMMDD.gif Image files of the daily residue are available in GIF format. The files present the daily residue of year 20YY, month MM, and day DD projected onto the world map. ------------------------------------------------------------------------ ../monthly/images/YYMM.gif Image files of the gridded monthly averaged AAI are available in GIF format. These files present the monthly averaged AAI of year 20YY and month MM projected onto the world map. ________________________________________________________________________ Daily log files are available for each processed day: ../daily/logs/20YY/YYMMDD.log These files contain all processing information. Log files are also available for days where no SCIAMACHY data were available. ________________________________________________________________________ References (follow the links on the webpage to download): [1] M. de Graaf, L.G. Tilstra, and P. Stammes, SCIAMACHY Absorbing Aerosol Index: The scientific product compared to the operational product and TOMS data, ESA SP-562, 2004. [2] M. de Graaf and P. Stammes, SCIAMACHY Absorbing Aerosol Index - calibration issues and global results from 2002-2004, ACP 5, 2005. [3] L.G. Tilstra, M. de Graaf, S. Noel, I. Aben, and P. Stammes, SCIAMACHY's Absorbing Aerosol Index and the consequences of instrument degradation, ESA SP-642, 2007. [4] L.G. Tilstra, M. de Graaf, I. Aben, and P. Stammes, Analysis of 5 years of SCIAMACHY Absorbing Aerosol Index data, ESA SP-636, 2007. [5] L.G. Tilstra, SCIAMACHY Absorbing Aerosol Index - Algorithm Theoretical Basis Document, SRON-EOS/RP/08-023, 2010. [6] L.G. Tilstra, SCIAMACHY Absorbing Aerosol Index - Product Specification Document, KNMI/SC-AAI/PSD/01, 2010. ________________________________________________________________________