******************************************************************************* ***** ***** ***** WORLD OZONE DATA CENTRE (WODC) DOCUMENTATION NOTES ***** ***** ***** ***** ***** ***** README.UMK ***** ***** ***** ***** by ***** ***** ***** ***** Edward W. Hare ***** ***** ***** ***** ***** ***** Date of last update: September 30, 1997 ***** ***** ***** ******************************************************************************* 1.0 INTRODUCTION ------------ Umkehr data submitted to the WODC (representing both morning and evening observations) are measurements made using the Dobson spectrophotometer only. Umkehr profile data submitted to and reported by the WODC have traditionally been represented by a terse, format which optimised the available fields in a rather restrictive, 80 column "card" limit. Although the record length restrictions still exist, these limitations pose no problems to the method of reporting current Umkehr data. For reasons of continuity, this method of data formatting (i.e. reporting) is still maintained within the bi-monthly, Environment Canada/WMO publication "Ozone Data for the World" (ODW) redbook. In addition, these line length restrictions are necessary to run the C-Umkehr inversion algorithm developed by Mateer and Deluisi in 1992. This data format is still used as a reporting format for the bi-monthly ODW redbooks. Please refer to the file "readme.mk2" for further details on the inversion program output format. While investigations of a new data reporting standard for all WODC data types are ongoing, the following document will assist data clients with the current interpretation of the data fields, special coding and how to access the data. This document is in two parts: Part I refers to descriptions for the "raw" Umkehr data format while Part II examines the processed vertical distribution profile data format. These data are the outputs from the New C-Umkehr retrieval program developed by Carl Mateer. Refer to the README.MK2 file in subdirectory: software/Umkehr/Dobson for a complete description of the program operation. For further information regarding the retrieval approach refer to the following publication: "A new Umkehr inversion algorithm" by C.L. Mateer and J.J. Deluisi (1992) in the Gotz Centennial issue of Journal of Atmospheric and Terrestrial Physics, Volume 54, number 5, pages 537-556. 2.0 HISTORICAL (ARCHIVED) DATA -------------------------- Within the archive/umk subdirectory, each station (stn###.umk) file represents a time series of all Umkehr profile data observed at that particular station since the station began submitting data to the WODC. All available Umkehr data are concatenated into this single station file and these files are updated annually reflecting both current and revised data submissions over the past calendar year. The issue of absorption coefficients (Bass and Paur (B-P) versus Vigroux) remains a topic of interest due in part to the date of transition from the Vigroux to B-P scale. Prior to January 1, 1992, total ozone data had been reported on the Vigroux scale. Since 1992, the B-P coefficients have been in use. Where some confusion occurs is with the submission of revised data. Many stations are re-evaluating and revising their data sets based on the B-P scale. Strictly speaking, data submitted for collection dates prior to 1992 should be in Vigroux. The WOUDC reports ALL data in the database using the B-P scale and encourages stations to now submit their revised data based on the B-P scale. Thus, all retrieved Umkehr profile data have been adjusted to the B-P scale. 2.1 Current WMO/WOUDC Data Input/Output Format - ----------------------------------------- Umkehr data which has not yet been processed through the C-Umkehr vertical distribution software is often called "raw" Umkehr. These data undergo quality control and pre-processing. Individual Umkehr data records (either "raw" or "processed") represent both a unique time and wavelength setting. Thus, if a morning and evening schedule have been established and measurements are made over the A,C and D wavelengths, then a single day of Umkehr observations can yield up to maximum of 6 records. ------------------------------------------------------------------------------- * NOTE: Included with the description of each data field parameter is an additional descriptor: NULL or NOT NULL which is used to identify those parameters required by the database loading software. ANY parameter tagged with a NOT NULL means that this field IS REQUIRED in the input data file in order to be accepted into the WODC database. Also included are "typical" or expected ranges for values. ------------------------------------------------------------------------------- PART I: "RAW" UMKEHR DATA ------------------------- Each record begins with "meta" data about the observation, followed by the N-values of the measurements observed over 14 standard zenith angles (SZA). Up to mid-1993 the first 5 columns were reserved for the 5 digit WMO station number. However, these five columns are now used to report the instrument type and serial number. The general representation is: [Header information] [log(I'/I + constant) for 14 SZA] [Station] (Solar Zenith Angles: 60 65 70 74 75 77 80 83 84 85 865 88 89 90) ICIII DDMMYY HWLSXXX NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN STN Header field (columns 1-20) --------------------------- IC Instrument type code Range: restricted to the following codes: (NULL) 03 Dobson 04 Dobson (Japan) III Instrument serial number Range: 001-999 (Japanese Dobsons: 5001-5999) (NULL) Note: If IC=04, the preceding "5" is implied. DD Day Range: 01-31 (NOT NULL) MM Month Range: 01-12 (NOT NULL) YY Year Range: 00-99 (NOT NULL) H Time of observation code Range: 0-2 (NULL) Code types: 0 = time unknown (Note: if blank code = 0) 1 = A.M. (before local noon) 2 = P.M. (after local noon) W Wavelength pair used for observation (represented as a code) Range: 1,3,4 or 5 (NOT NULL) Wavelength code: 1 = A wavelength 3 = C " 4 = D " 5 = Non-sun observation (adjusted to = DS observation) L Wavelength used for total column ozone measurement Range: 0 to 9 (NOT NULL) 0 = AD wavelengths, ordinary setting 1 = BD wavelengths, ordinary setting 2 = CD wavelengths, ordinary setting 3 = CC' wavelengths, ordinary setting 4 = AD wavelengths, focused image 5 = BD wavelengths, focused image 6 = CD wavelengths, focused image 7 = CC' wavelengths, focused image 8 = other (often used for filter instruments) 9 = other (often used for Brewer instruments) S Type of total ozone measurement (direct sun, zenith sky, focused moon etc.) Range: 0 to 9 (NOT NULL) 0 = Direct Sun 1 = Focused Moon 2 = Zenith Blue Sky 3 = Zenith Cloud (uniform stratified layer of small opacity) 4 = Zenith Cloud (uniform or moderately variable layer of medium opacity) 4 = Zenith Cloud (uniform or moderately variable layer of large opacity) 6 = Zenith Cloud (highly variable layer with or without precipitation) 7 = Zenith Cloud (fog) 8 = other (specify) 9 = other (specify) XXX Total amount of column ozone (in Dobson units) applicable to the Umkehr observation. Range: 75 to 600 (NOT NULL) Data fields (columns 21-76) --------------------------- NNN Log(I'/I + constant) to 3 decimal places for the SZA of the sun indicated in the list below. The SZA is given to the nearest tenth of a degree, with the decimal point missing. Refer to the Special Codes section for details. SZA: 60,65,70,74,75,77,80,83,84,85,86.5,88,89,90 Range: 0 to 999 (NOT NULL) (NOTE: a leading blank(s) is acceptable, a -1 indicates no data) Station identifier field (columns 78-80) ---------------------------------------- STN The WODC 3 digit station number Range: 1 to 999 (NOT NULL) Sample Data set: On October 7, 1992, Dobson(03) instrument(#077) at station 65 (Toronto) reports both a morning (1) and afternoon observation (2) on all wavelengths (1,3,4) and a total column ozone observation on AD wavelength/direct sun (00) with AM/PM values of 268 and 244 Dobson units respectively. ICIII DDMMYY HWLSXXX NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN NNN STN 03077 071092 1100268 -1 145 356 572 627 746 913 957 942 916 844 763 705 630 065 03077 071092 1300268 467 538 645 768 800 877 44 231 295 343 363 344 316 271 065 03077 071092 1400268 208 244 292 254 371 416 504 629 681 734 817 893 920 917 065 03077 071092 2100244 -1 145 356 572 627 746 913 957 942 916 844 763 705 630 065 03077 071092 2300244 467 538 645 768 800 877 044 231 295 343 363 344 316 271 065 03077 071092 2400244 208 244 292 254 371 416 504 629 681 734 817 893 920 917 065 PART II: NEW C-UMKEHR VERTICAL DISTRIBUTION DATA ------------------------------------------------ Umkehr data which has been processed through the new C-Umkehr vertical distribution program, written by Carl Mateer, is referred to as "Umk" data. ALL "raw" Umkehr data submitted to the WODC is submitted to this program which involves a pre-processing step to yield the final "Umk" retrieval data. This ensures a consistent data set in terms of the retrieval algorithm. A final quality control check of the retrieved data is made prior to the data being accepted into the database. Data submitters are encouraged to submit their versions of the retrieval data, but these outputs will be placed into a "special" directory. The general form of the record is: [header] [Data (layer values 10-01)] [Statistical summary] [Station] DD,MM,YY,H,W,OBSR,RETRV,Layer10 ... Layer 01,IT,Sx,SZA_x,DFRMS,FEPS,RMSres,STN Header Field (columns 1-9) -------------------------- DD Day Range: 01-31 (NOT NULL) MM Month Range: 01-12 (NOT NULL) YY Year Range: 00-99 (NOT NULL) H Time of observation Range: 0 to 2 (NOT NULL) Code types: 0 = time unknown (Note: if blank code = 0) 1 = A.M. (before local noon) 2 = P.M. (after local noon) W Wavelength pair used for observation (represented as a code) Range: 1,3,4 or 5 (NOT NULL) Wavelength code: 1 = A wavelength 3 = C " 4 = D " 5 = Non-sun observation (adjusted to = DS observation) Data Fields (columns 10-62) --------------------------- OBSR Observed total column ozone (analogous to XXX) in Dobson units. Range: 75 to 600 (NOT NULL) RETRV Retrieved value for total ozone in Dobson units. Range: 750 to 6000 (NOT NULL) Note: This is an integer value with an implied decimal. LO3 Computed ozone amount in each layer (Dobson units). (x10) Range: 0.00 to 99.99 (NOT NULL) Note: These values are integer representations with implied decimal points. Refer to the section on Special Codes. Retrieval statistics (columns 63-77) ------------------------------------ IT Number of iterations Range: 1 to 9 (NOT NULL) Note: typically values are 2-5 SX Matrix model Accepted values: U = Uniform model (NOT NULL) C = Climate model SZA_x Solar zenith angle (max and min) SZA_max Range: 1 = 90 degrees (NOT NULL) 2 = 89 degrees SZA_min Range: 10 = 70 degrees 11 = 65 " 12 = 60 " DFMRS RMS fractional retrieval change Range: 000 to 999 (NOT NULL) FEPS RMS change in forcing vector Range: 000 to 999 (NOT NULL) RMS RMS fit residual Range: 000 to 500 (NOT NULL) Station field (columns 78-80) ----------------------------- STN WODC station number Range: 1-999 (NOT NULL) SAMLE DATA SET -------------- For example: Station 260 (Table Mountain, USA) produced 2 "clean" retrievals on August 1, 1989 for an AM and PM observation using the Uniform matrix model. 1 88913 289 2869 126 284 909 246 465 658 650 330 165 222 2U112 7 11 59260 1 88923 304 2996 118 229 627 177 427 617 760 431 224 263 5U112 48 13 174260 3.0 INTERPRETATION of CODES ----------------------- The SZA is given to the nearest tenth of a degree, with the decimal point missing. When log(I'/I + constant) exceeds unity, the integer is omitted. Example: 1.231, NNN is coded 231. Leading zeroes may or may not be present, and a -1 indicates no data. 4.0 FURTHER INFORMATION ------------------- Further information can be obtained from the WOUDC ODW Guidebook No. 2 or any other ODW publications like the bi-monthly issues or the annual index. Consult other WOUDC "readme" files or contact the WOUDC directly at: Phone: 1-416-739-4635 Fax: 1-416-739-4281 or Internet: woudc@ec.gc.ca 5.0 ACKNOWLEDGEMENTS ---------------- Larry Morrison and Carl Mateer have contributed many helpful suggestions and explanations of the data codes. Their contributions have assisted me in the writing of this document. *******************************************************************************