Wind Statistics

For each of the sea area, season, directional sector records, the database contains a probability distribution giving 13 values of probability corresponding to the Beaufort numbers 0 - 12.

These distributions were obtained by applying a normalising procedure to the 'All Wind' data stored in the Marine Databank, as explained in Appendix A2.

The program presentation, whilst being based on Beaufort number, also gives the appropriate wind speed range in knots. It should be noted that the speeds given are those of the so-called 'Scientific Beaufort Scale' [3] which has been used throughout the NMIMET analysis procedures, because it is widely considered to be quantitatively more reliable.

The relationship between Beaufort number and wind speed is as follows:

Beaufort No. Wind Speed (kn)
  Mean Range
(approx)
0 1.56 < 2.7
1 3.89 2.7- 5.4
2 7.00 5.4- 8.9
3 10.89 8.9-13.0
4 15.17 13.0-17.5
5 19.84 17.5-22.2
6 24.51 22.2-26.9
7 29.37 26.9-32.0
8 34.62 32.0-37.5
9 40.46 37.5-43.8
10 47.07 43.8-50.8
11 54.46 50.8-58.3
12 62.24 >58.3
Table 1 - Scientific Beaufort Number Scale of Wind Force

The total number of (unnormalised) 'All Wind' observations for a sea area are given in each case on the Season Selection Menu.

In the world-wide database valid wind data exists for all 104 sea areas, 5 seasons and 9 directional sectors, ie. 4680 records.