.tab file format
Overview
The .tab file describes a measured wind climate. It contains the frequencies of occurrence of the wind in a number of direction sectors (the wind rose) and wind speed bins. It further contains the height of observation above ground level and the geographical coordinates (latitude and longitude) of the measurement. Data are stored in an ASCII (text) file with the default file name extension 'tab'. The general format of the file is shown below (and WindFarmer specific expectations are described further down).
| Line | Contents |
|---|---|
| 1 | Text string identifying the source data |
| 2 | Latitude [°], Longitude [°] and height a.g.l. of anemometer [m] |
| 3 | Number of sectors, speed factor au and direction offset bd [º] |
| 4 | Sector-wise frequencies of occurrence [%] |
| 5 | Upper limit for speed class 1, sector-wise frequencies [%] in class 1 |
| 6 | Upper limit for speed class 2, sector-wise frequencies [%] in class 2 |
| 7–n | Same as line 5 and 6, but for speed class 3–n |
- Numbers in the same line of the file must be separated by blank space(s) or a tabs.
- The speed distributions may be described by a maximum of 50 wind speed bins and 36 sectors.
- Direction sectors are considered of equal angular width.
Latitude and Longitude
The location/position of the measured wind climate (anemometer) must be given in geographical coordinates, i.e. as latitude and longitude in decimal degrees. Conventionally, latitude N and longitude E are considered positive, latitude S and longitude W negative. Latitude can thus take values between -90º and +90º and longitude values between -180º and +180º.
WindFarmer default *.tab file
The WindFarmer default tab file imposes the following extra requirements:
- Speed bins are centred on integer values, the first bin is smaller: 0 to 0.5 m/s. This implies that any speed bin speed up au is always taken to equal 1.
- No wind rose rotation due to direction offset bd is taken into account.
- The frequencies of occurrence of wind speed are given in per mille [‰], i.e. they will add up to 1000 for each sector.
The following window shows part of a tab file, corresponding to the description given above.
