These 1-character duration codes are used in netCDF variable names and variable attributes to indicate the frequency with which data is reported. The codes are taken from the SHEF (Standard Hydrometeorological Exchange Format) format defined by the National Weather Service. The codes are in lowercase letters when used in the variable names, and in uppercase letters when listed in the variables' attributes.
| Code | Time Period |
|---|---|
| I | Instantaneous/Irregular -- Used for sensors whose data is specific to a given instant in time rather than to a time period. The data is usually reported at irregular intervals (event data, etc.). |
| U | 1-minute |
| C | 15-minute |
| J | 30-minute |
| H | 1-hour |
| B | 2-hour |
| T | 3-hour |
| F | 4-hour |
| Q | 6-hour |
| A | 8-hour |
| K | 12-hour |
| L | 18-hour |
| D | Daily (Midnight to Midnight) |
| P | Daily (7 AM to 7 AM) |
| G | Random 24-hour period (Usually used for data statistics rather than observed data) |
| W | Weekly |
| M | Monthly |
| Y | Yearly |
| S | Seasonal -- time period varies, usually used for year-to-date or season-to-date data. |
| R | Period of record |