Met Éireann - the Irish Meteorological Service at www.met.ie - operates
a number of off-shore wave buoys in collaboration with the Irish Marine Institute
(www.marine.ie) and the UK Met Office (www.metoffice.com).
Met Éireann has kindly provided DMI with 10 days of data from
buoys no.s M1, M3 and M4, as indicated on the map.
The significant wave height Hs is compared with DMI-WAM hindcasts
for the period 26 Oct - 7 Nov 2003.
The direct comparison is shown in the upper plot panel,
and summarised in the table below.
The model predictions are very good, with a scatter index below 10%, but there are still
temporary obs-frc differences in excess of 1 meter (e.g., buoy M3 on Oct. 31st.)
| Hs error | M1 | M3 | M4 |
| bias | -0.21m | -0.13m | -0.32m |
| r.m.s. | 0.35m | 0.27m | 0.21m |
| s.i. | 0.09 | 0.07 | 0.09 |
The scatter index (s.i.) is defined as the r.m.s. error relative to
the mean wave height.
The plot panels further down compare mean wave direction and wave period.
These parameters are predicted less well than Hs. It should be noted
that the buoys report wind direction, not wave direction. The wave period
is overpredicted. The reason for this is unresolved.
|
