File Naming Convention (2004-03-15) ---------------------- This document describes the file naming convention used in the exchange data archives. The naming convention was adopted in 1998 as an extension to the old, DOS-compatible naming convention. The file naming convention uses the ISO 9660 convention which permits "name.ext" to be 30 characters, and uses the character set: 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_ Notice that the alphabetic characters are upper case. The general expression for any file name is: CCyyyyMMdd[_[hh[mm[ss]]][_I]].P The square brackets [] enclose optional parameters, and the total length of the file name, including the "." (period), does not exceed 30 characters. The "_" (underscore) is used to separate optional parameters. The definitions of the component parameters are: CC = two-character prefix for the file name (0-9, A-Z). Ideally, this will be a mnemonic code for the measurement, instrument, or subject of the file. yyyy = four digits specifying year (i.e. 1997, 2001, etc.). MM = two digits specifying month number (01-12). dd = two digits specifying day number (01-31). hh = optional two digits specifying hour (00-23). mm = optional two digits specifying minutes (00-59). ss = optional two digits specifying seconds (00-59). I = one or more characters used to further specify the contents of the file or the subject of an image. This parameter is usually optional (in the sense that we can decide to use it or not), but there are two cases where it is required. If a data file is one volume of a multi-volume dataset then a volume counter "Vn" (i.e. V1, V2, V3, etc.), must appear at the end of the "I" identifier, and be separated by an "_" from the rest of the identifier. * The volume number (the "n" in "Vn") must match the volume number (IVOL) in the sixth line of the file header. * The number of digits used in each volume number must be the same (V1,V2,V3,..., or V01,V02,V03,..., etc.). * If "Vn" is omitted from the file name then volume number one of a one-volume dataset is implied. If the contents of the file pertain to a second or third aircraft launch on the indicated date then a launch counter "Ln" (i.e. L2, L3, etc.) must appear at the end of the "I" identifier, but before a volume counter, and be separated by an "_" from the rest of the identifier. If "Ln" is omitted from the file name then launch number one is implied. P = two or more characters to identify the measurement platform, source, or association of the data (for data files), or image type (for image files). Some things to notice are: * Dates and times in file names are always UTC. * In general, the date and time in the file name give the date/time at which the data within the file begin (data files), or date/time at which the image applies (image files). For aircraft data files, the date always refers to the UT date of launch, and further specification of time in those file names is discouraged. * There can be two, four, or six digits following the first "_", which represent hh, hhmm, or hhmmss. * If the "I" identifier is used without a time, then it is separated from the date by two "_" (e.g. CCyyyyMMdd__I.P). * File name codes are constructed from the constant parts of the file names and used as a shorthand way to reference a particular type of file. Usually the file name code will be CC.P, but it can be CC__c.P, where "c" represents the constant part of the "I" identifier ("Ln" and "Vn" are variable parts of "I"). * For any given experiment, all file name codes must be unique. If two or more file names use the same prefix "CC" and extension "P" then all of those names must also include a "c" identifier, and those identifiers must be unique for each type of file. * File catalogs (datatable.txt and imagetable.txt) will be provided for each experiment to link file name codes, and therefore file names, with the contents or subject of each type of file. File Name Extensions -------------------- The file name extension, P, is used to identify the measurement platform, source, or association of the information within a data file, or the type of image file. A list of the file name extensions which are currently being used in the archives is given below. Others will be defined as needed. AERI = Ground based Atmospheric Emitted Radiance Interferometer B747 = B-747 aircraft B757 = B-757 aircraft BAL = Gondola balloon BOS = Ground based Brewer Ozone Spectrophotometer CIT = Citation aircraft DC8 = DC-8 aircraft DROP = Dropsonde DS = Ground based Dobson Spectrophotometer ER2 = ER-2 aircraft FAL = Falcon aircraft FTIR = Ground based Fourier Transform Infrared Spectrometer GDAO = GSFC Data Assimilation Office GIF = GIF image file GOME = Global Ozone Monitoring Experiment HCR = Harvard University Chemical Reconstructions JPG = JPEG image file LIDAR = Ground based LIDAR M300D = Ground based Benthan M300-D NLDN = National Lightning Detection Network NMCA = National Meteorological Center Analysis NPOL = NPOL Radar O3SND = Ozonesonde balloon P3 = P-3 Orion aircraft PARSL = PNNL Atmospheric Remote Sensing Laboratory PCO = Portable Cloud Observatory PDF = PDF image file PNG = PNG image file POAM3 = Polar Ozone and Aerosol Measurement III PROT = Proteus aircraft PS = PostScript image file RAMS = Ground based Radiation Measuring System RAOB = Radiosonde balloon ROCK = Rocket RRM = Rosenfield Radiation Model SAGE2 = Stratospheric Aerosol and Gas Experiment II SAM2 = Stratospheric Aerosol Measurement II SBAL = Small Balloon T39 = T-39 aircraft TGM = Ground based Trace Gas Monochromator TO = Twin Otter aircraft TOMS = Total Ozone Mapping Spectrometer UARS = Upper Atmospheric Research Satellite VISST = Visible Infrared Solar Split-window Technique retrieval algorithm WB57 = WB-57 aircraft Examples -------- Some examples of file name codes, file names, and explanations of the meaning of the file names are given below to illustrate the construction of file codes and file names. File code File name Explanation ---------- --------------------- --------------------------------- O3.ER2 O319920116.ER2 ER-2 O3 file, 16 Jan 1992 launch. MM.DC8 MM19960416.DC8 DC-8 MM file, 16 Apr 1996 launch. NA.T39 NA19960507__L2.T39 T-39 NA file, 7 May 1996 launch #2. M4__SR.BAL M419970508__SR.BAL Balloon M4 file, 8 May 1997 launch, sunrise (SR) obs. RS.RAOB RS19920116_00.RAOB Radiosonde RS file, 16 Jan 1992, 00Z launch. WV.GIF WV19970511_18.GIF GIF image of GOES water vapor channel for 11 May 1997 at 18Z. NP.ER2 NP19990116__L2_V3.ER2 ER-2 NP file, 16 Jan 1999 launch #2, volume #3.