Two letter codes are used quite often in the scientific literature, which suggests there exists a standard, but I was unable to find a WMO standard. Thus we would suggest to follow standard two-letter conventions.
| Code | Element | Unit |
| Wind | ||
| dd | wind direction | [in degrees; calm = -1] |
| ff | wind speed | [in m/s] |
| Temperatures | ||
| tm | mean temperature | [in °C] |
| tn | minimum temperature | [in °C] |
| tx | maximum temperature | [in °C] |
| tr | read temperature (at a specific time) | [in °C] |
| tw | wet-bulb temperature | [in °C] |
| ts | surface temperature | [in °C] |
| Radiation | ||
| sn | sunshine duration | [in h] |
| sd | solar radiation flux down | [in W m-2] |
| su | solar radiation flux up | [in W m-2] |
| hd | infra-red (heat) radiation flux down | [in W m-2] |
| hu | infra-red (heat) radiation flux up | [in W m-2] |
| Snow | ||
| ts | total snow | [in mm] |
| ns | new snow | [in mm] |
| Diverse | ||
| rh | relative humidity | [in %] |
| pp | pressure | [in mbar] |
| rr | precipitation | [in mm per day] |
| nn | cloud cover | [in %] |
If you know of an existing system, please say so. Many codes are quite common in the literature, but some also less. If you have suggestion for other codes for these or would like to propose abbreviations for other variables, please contact us or write a comment below.
Hi, Victor,
ReplyDeleteI was thinking the weather observation synoptic code might be useful http://atmo.tamu.edu/class/atmo251/LandSynopticCode.pdf , but many of of the variables are more than two digits. -bob bkellysky.wordpress.com
Thanks. The synoptic code may explain why we use dd and ff for wind and not just d and f because it is specified in two digits. That may explain this custom; I was wondering whether it indicated an existing standard.
ReplyDeleteI would not mind if the codes were 3 or 4 characters, but I would prefer them to have the same length, otherwise I would have to add delimiters to the file names to make them easy to read automatically. And the names are already quite long.
Right. I can see why you'd prefer 2 characters!
DeleteTwitter suggested to use wd and wf for wind direction and speed. My impression is that dd and ff are used more.
ReplyDeleteWhy do you need codes? Why not just use the human readable names, even if they are a little long. What is the problem caused by a long filename?
ReplyDeleteecmwf's grib tables have many abbreviation, some two letters, most three, some 4 (at most) and the names are rather meaningful
ReplyDeleteMark, what is a need? ;-) It can naturally be done differently. It would be nice if all variables names/codes are the same length. The filenames also denote the station, averaging scale, processing stage and a directory with one parallel measurement would contain several files. If the codes are all the same length, it is easier to compare them with each other in a directory and see what you have.
ReplyDeleteJon, the nice thing about GRIB is that it is a real standard, except maybe for the tables the weather services use individually. But some codes are also longer. Just found "mean2t24" for "Mean temperature at 2 metres in the last 24 hours". Probably unavoidable in case of model data because there are so many variables.