STANDARD FORMAT FOR COSMIC RAY GROUND-LEVEL ENHANCEMENT DATA A standard format for cosmic ray ground-level enhancement data was suggested at the l9th International Cosmic Ray Conference /1/. Several problems were encountered in compiling data for both recent and historical events and a revised standard format was presented at the 20th ICRC in Moscow /2/. Additions to the published format now include an optional comment code in column 40 of the data file, an end-of-data indicator, provision for comments to clarify data problems, and an end-of-dataset indicator. The complete format description follows. HEADER INFORMATION. The header lines should provide accurate station information in the exact format described in the following list: Line 1: Columns 1-10: Station Name (abbreviated if necessary). Columns 12-19: The word "LATITUDE". Columns 22-27: Station latitude (F6.2). Indicate southern latitudes by a minus sign in Column 22. Columns 32-40: The word "LONGITUDE". Columns 44-49: Station longitude (F6.2) in degrees east of Greenwich; all positive numbers. Columns 54-61: The word "ALTITUDE". Columns 64-67: Station altitude (I4) in meters above sea level. Column 69: The letter "M" to designate meters. Line 2: Columns l-10 : Station Name (abbreviated if necessary). Columns 12-21: The word "INSTRUMENT". Columns 24-31: Start of instrument description: For an NM-64 the designation is ##-NM-64 where ##, the number of tubes, is in columns 24-25. For an IGY monitor, IGY appears in columns 26-28 and the remaining columns are blank. For other instrumentation leave columns 24-31 blank and utilize columns 34-75 as indicated. Columns 34-75: The type of detector (e.g. neutron monitor). If the detector is an ionization chamber, a muon telescope, or a specialized instrument such as a bare counter or multiplicity counter, indicate that here and leave columns 24-31 blank. Line 3: Columns 1-10: Station Name (abbreviated if necessary). Columns 12-28: The words "STANDARD PRESSURE". Columns 31-37: The standard pressure (F7.2). If the standard pressure is in centimeters or inches use (F7.2); if in millimeters or millibars, use (F6.1, 1X). Columns 41-44: The units of the pressure: "MMHG", "CMHG" or "INHG" as appropriate. If "MB" is used, the letters go in columns 42 and 43 with columns 41 and 44 blank. Columns 47-57: The word "COEFFICIENT". Columns 60-66: The value of the barometric pressure coefficient in percent per unit pressure (F7.4). Column 68: The percent sign (i.e. %). Column 70: The slash sign (i.e. /). Columns 72-75: The units of pressure: "MMHG", "CMHG", or "INHG" as appropriate. If "MB" is used, the letters go in columns 73 and 74 with columns 72 and 75 blank. Line 4: Columns 1-10: Station Name (abbreviated if necessary). Columns 12-46: The words "PRE-INCREASE BASELINE TIME INTERVAL" Columns 50-55: The year, month and day of the pre-increase baseline time interval (3I2). Columns 59-64: The hour, minutes and seconds of the start of the baseline time interval (3I2). Column 65: The hyphen (i.e. -). Columns 66-71: The hour, minutes and seconds of the end of the baseline time interval (3I2). Columns 74-75: The letters "UT". Note that the baseline time interval is the interval from which the percentage increase is calculated. The complete hour (in UT) before the onset of the particle increase at the Earth is the commonly used time interval. For example, the earliest onset for the increase on 07 May 1978 was approximately 0335-0338 UT; thus the baseline from which percentage increases are determined is the average counting rate for the hourly interval 0200-0300 UT. For historical data where only bihourly records are available, the baseline is the two-hour interval prior to the earliest onset. Line 5: Columns 1-10: Station Name (abbreviated if necessary). Columns 12-45: The words "PRE-INCREASE AVERAGE COUNTING RATE". Columns 50-56: The value of the pre-increase average counting rate in counts per second (F7.2). Columns 59-75: The words "COUNTS PER SECOND". Line 6: Columns 1-10: Station Name (abbreviated if necessary). Columns 12-25: The words "TIME INTERVALS". Columns 29-32: The number of seconds (I4) in the largest time interval of data in this dataset (i.e. 3600 for hourly data). Columns 33-72: The number of seconds in the various time intervals used in the dataset in a 5(4X,I4) format. (For example if both 5-minute and 1-minute data are included the following would appear: bbbbb300bbbbbb60 where b indicates blanks.) A total of 6 time intervals can be given. Line 7: Columns 1-10: Station Name (abbreviated if necessary). Columns 12-24: The words "SCALE FACTORS". Columns 30-35: The scale factor used in the largest time interval (F6.2). (For example if the scale factor for the hourly counting rate is 128, this is given as 128.00.) Columns 36-75: The scale factors used for each of the various time intervals given in columns 33-72 of Line 6 in the same order as given on that line. The format is 5(2X,F6.2). Note to Principal Investigators regarding scale factors: We used slightly different methods of recording scale factors in the two ongoing GLE database projects. In the data files we compiled for the GLEs of 1956-1984, the scale factors generally are those given in the original data reports along with the absolute counts measured during the indicated time intervals. The scale factors were used to calculate the counts per second from the original data. Since we found so much conflicting information in the data reports, we felt the user should be able to evaluate the results (cps, percent increases) given in the final files. So we left the scale factors as is to enable users to convert to the absolute number of counts per time interval if necessary, until we have confirmation from principal investigators that we processed the data correctly. The GLE data for Solar Cycle 22, however, have, for the most part, been sent by the principal investigators in the counts per second standard format. Once this conversion is done and the data are verified, the correct scale factor for a counts per second file is 1. Principal investigators who are sending data in the final counts per second format, should use a scale factor of 1. for all time intervals. Lines 8 and 9 are column headers for the data that follow. Line 8: Columns 1- 7: The word "STATION". Columns 12-17: The letters "YYMMDD" indicating year, month, and day. Columns 20-22: The letters "SEC" indicating the number of seconds in the time interval. Columns 26-34: The words "TIME (UT)". Columns 37-40: The word "CODE". Columns 44-50: The letters "UNCORR." indicating values not corrected for barometric pressure. Columns 52-57: The letters "PRESS." indicating barometric pressures. Columns 63-67: The letters "CORR." indicating values corrected for barometric pressure. Columns 70-75: The identification "% INC." indicating percentage increase (i.e. above baseline). Line 9: Columns 26-33: The word "INTERVAL". Column 38: The letter "T" for the Time code (see below). Column 39: The letter "D" for the Data code (see below). Columns 46-48: The designation "C/S" indicating counts per second. Columns 52-57: The units of pressure within parentheses as follows: "(MMHG)", "(CMHG)", "(INHG)", or "( MB )". Columns 64-66: The designation "C/S" indicating counts per second. DATA FORMAT. Cosmic radiation data should be provided in the following format: Columns 1 - 10: Station identification (alphanumeric; abbreviated if necessary, and identical to identification in header). Columns 12 - 17: Year, month and day (3I2). Columns 19 - 22: Number of seconds in this time interval (I4). Columns 24 - 36: The hour, minutes, and seconds of the beginning and end of this time interval (3I2, 1H-, 3I2). Column 38: Time code as follows: 0 - Time accurate to nearest minute. 1 - Time accurate to nearest second. 2 - Time accurate to nearest 10 seconds. 3 - Time accurate to nearest 30 seconds. 7 - Time uncertainty 1 to 5 minutes. 8 - Time uncertainty greater than or equal to 5 minutes. 9 - Probable time error of unknown amount in source data; time given has been adjusted. Column 39: Data code as follows: 0 - Uncorrected, pressure (measured) and corrected cosmic ray data given. 1 - Uncorrected, pressure (interpolated) and corrected data given. 2 - Only corrected cosmic ray data given. 3 - Only uncorrected cosmic ray data given. 4 - Corrected and uncorrected cosmic ray data only. (No pressure given for observation period; insufficient information for pressure interpolation.) 5 - Only percentage increase given. (Baseline time interval used may be different from standard.) 6 - Cosmic ray data do not exist (e.g. due to calibration, equipment failure, etc.) 9 - Existence of cosmic ray data unknown. Column 40: Optional comment code * to indicate time intervals during which specific problems have occurred, such as equipment failure or reduced precision in the data. Comments should be added at the end of the data file, following the end-of-data indicator, and preceding the end-of-dataset indicator as described. Columns 42 - 50: Uncorrected counting rate; counts per second (F9.2). Columns 52 - 58: Barometric pressure. Use (F7.2) if pressure is in centimeters or inches; use (F6.1, 1X) if pressure is in millimeters or millibars. Columns 60 - 68: Corrected counting rate; counts per second (F9.2). Columns 70 - 75: Percentage increase (F6.1) above the pre-increase average counting rate determined from the baseline time interval. Line following the last data entry: Column 1: End-of-data indicator *. Remainder of line is blank. Line(s) following the end-of-data indicator: Columns 1 - 7: The word "COMMENT". Columns 12 - 17: Year, month, and day of the data marked by the comment code. Columns 19 - 31: Time interval of the data marked by the comment code. Columns 33 - 75: Description of the data marked by the comment code. The comment lines may also be used to indicate that the data have been verified by the principal investigator. Final line of the datafile: Columns 1 - 75: A full line of asterisks to indicate the end-of-dataset. It is hoped that all cosmic ray data for ground-level enhancements will now be reported to the World Data Centers in this standard format, and that an effort will be made throughout the community to utilize this format to archive data from past events. REFERENCES 1. Shea, M.A., D.F. Smart, M. Wada, and A. Inoue, 19th ICRC, Conference Papers, 5, 510, 1985. 2. Shea, M.A., D.F. Smart, J.E. Humble, E.O. Fluckiger, L.C. Gentile, and M.R. Nichol, 20th ICRC, Conference Papers, 3, 171, 1987.