This file format, designed in conjunction with the Joint Archive for Sea Level at the University of Hawaii, is used to report daily values. The format contains four record types:
1 - HEADER 1, DATE, POSITION, TIME AND LEVEL REFERENCE, AND UNITS
2 - HEADER 2, STATION NAME, COUNTRY, AND CONTRIBUTING AGENCY
3 - STATION INFORMATION, QUALITY ASSESSMENT, AND PROCESSING POLICY
5 - DAILY SEA LEVEL VALUES IN MILLIMETERS
Each file contains 80-byte, fixed-length records, which are sorted by unique station, date, and record type. The first nine columns of all records are FILE TYPE (bytes 1-3) and TRACK NUMBER (bytes 4-9), which is used by NODC internally. The file types for sea level will be 184, 185, or 186 for hourly, daily, and monthly values, respectively.
The fields of each record type are described shortly, but first, general characteristics of the data set and important information in the header records are discussed.
The data are linked to fixed bench marks of a sea level station. Data segments from the same site that are not linked to common bench marks are considered two independent time series and are given unique names that are distinguished by suffixing a letter alphabetically, such as Baltra-A and Baltra-B. The REFERENCE LEVEL OFFSET (record 1, bytes 64-68) is a constant that must be added to each value so the data are relative to the tide staff zero or the primary data. It is equal to 00000 in almost all cases. A REFERENCE FLAG, R, (byte 69) is suffixed to the REFERENCE LEVEL OFFSET to denote that the data are linked to a fixed datum.
The time reference of the data is given by a TIME ZONE OFFSET (record 1, bytes 71-74) in hours (to tenths with implied decimal). The data are relative to GMT (TIME ZONE OFFSET = 0000) unless the local time is offset from GMT by a non-integer value, in which case EAST of Greenwich is defined as '+' and WEST as '-'. For example, the data for Colombo, Sri Lanka are relative to a local time zone of GMT plus 5.5 hours; thus, TIME ZONE OFFSET equals 0055.
The NODC station number (records 1 and 2, bytes 11-18) is a 6-digit WMO number, which is unique to a one-degree square, suffixed with a 2-digit random number/character. In some cases, independent time segments may exist for a unique site as noted above; however, the NODC station number is the same for all independent time segments of a unique site.
Next, each field of the four record types is described. Note SC is the starting character or byte position in the record for the given field.
| PARAMETER | DESCRIPTION | STARTING COLUMN | FIELD LENGTH |
|---|---|---|---|
| RECORD TYPE 1: | |||
| FILE HEADER RECORD | ALWAYS "1" | 10 | 1 |
| NODC ASSIGNED STATION ID | UNIQUE CONCATENATION OF WMO TEN+ ONE+ 2 CHARACTERS | 11 | 8 |
| BLANKS | 19 | 1 | |
| TIDE STATION ID | ORIGINATOR'S STATION IDENTIFIER | 20 | 10 |
| BLANKS | 30 | 1 | |
| DATE | YYYYMMDD - STARTING DATE (GMT) | 31 | 8 |
| BLANKS | 39 | 1 | |
| DATE | YYYYMMDD - ENDING DATE (GMT) | 40 | 8 |
| BLANKS | 48 | 1 | |
| LATITUDE | DDMM PLUS HEMISPHERE 'N' OR 'S' | 49 | 5 |
| BLANKS | 54 | 1 | |
| LONGITUDE | DDDMM PLUS HEMISPHERE 'E' OR 'W' | 55 | 6 |
| BLANKS | 61 | 1 | |
| AVERAGING METHOD | ONE-CHARACTER CODE - as follows 1 : filtered 2 : simple average 4 : other or unknown | 62 | 1 |
| BLANKS | 63 | 1 | |
| REFERENCE LEVEL OFFSET | CONSTANT OFFSET THAT MUST BE ADDED TO EACH VALUE FOR THE DATA TO BE RELATIVE TO TIDE STAFF ZERO OR PRIMARY DATUM (IN SAME UNITS AS SEA LEVEL DATA). | 64 | 5 |
| DATA REFERENCED | ONE-CHARACTER CODE - as follows R : data linked to bench marks X : data not linked to bench marks | 69 | 1 |
| BLANKS | 70 | 1 | |
| TIME ZONE OFFSET | XXXX - + OR - HOURS TO TENTHS FROM GMT | 71 | 4 |
| BLANKS | 75 | 1 | |
| SEA LEVEL UNITS | XX ALWAYS MM (MILLIMETERS) | 76 | 2 |
| BLANKS | 78 | 3 | |
| RECORD TYPE 2: | |||
| PARAMETER | DESCRIPTION | STARTING COLUMN | FIELD LENGTH |
| SECOND HEADER RECORD | ALWAYS "2" | 10 | 1 |
| NODC ASSIGNED STATION ID | UNIQUE CONCATENATION OF WMO TEN+ ONE+ 2 CHARACTERS | 11 | 8 |
| BLANKS | 19 | 1 | |
| STATION NAME | NAME OF TIDE STATION | 20 | 16 |
| BLANKS | 36 | 1 | |
| COUNTRY | NAME OR ABREVIATION WHERE TIDE STATION IS LOCATED. | 37 | 16 |
| BLANKS | 53 | 1 | |
| AGENCY | DATA CONTRIBUTOR | 54 | 27 |
| RECORD TYPE 3: | |||
| PARAMETER | DESCRIPTION | STARTING COLUMN | FIELD LENGTH |
| DOCUMENTATION RECORD | ALWAYS "3" | 10 | 1 |
| SEQUENCE | SEQUENTIAL NUMBER FOR DOCUMENTATION RECORDS | 11 | 4 |
| TEXT | DOCUMENTATION TEXT | 15 | 66 |
| RECORD TYPE 5: | |||
| PARAMETER | DESCRIPTION | STARTING COLUMN | FIELD LENGTH |
| DAILY DATA RECORD | ALWAYS "5" | 10 | 1 |
| BLANKS | 11 | 1 | |
| DATE | YYYY - YEAR OF DAILY DATA | 12 | 4 |
| BLANKS | 16 | 1 | |
| DAY | 001-366 DAY OF FIRST OBSERVATION OF THIS RECORD | 17 | 3 |
| BLANKS | 20 | 1 | |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 21 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 26 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 31 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 36 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 41 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 46 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 51 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 56 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 61 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 66 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 71 | 5 |
| SEA LEVEL | DAILY SEA LEVEL VALUE | 76 | 5 |
TWELVE DAILY VALUES ARE PLACED IN EACH RECORD. THIS RECORD IS REPEATED UP TO 31 TIMES FOR EACH YEAR. MISSING VALUES ARE FLAGGED '99999' AND SPACE- FILLER FLAGS ARE DENOTED '-9999' ON THE 31ST RECORD OF EACH YEAR.
| CODE NUMBER | CODE NAME |
|---|---|
| 0505 | AVERAGING METHOD |
| 0506 | DATA REFERENCE INDICATOR |
| 0507 | INTERPOLATION METHOD |