Verification of HIRLAM with ECMWF physics compared
with HIRLAM reference versions
Cisco de Bruijn and Erik van Meijgaard1
Abstract
ECMWF physics has been successfully ported into the HIRLAM system, version 5.0.6.
Model integrations have been carried out in the reference framework at
0.5 degree horizontal resolution for the month December 1999 and a 14-day period in May 2000.
Relative to the reference HIRLAM version 5.0.6,
verification scores of near-surface parameters range from
neutral in the Spring period to significantly better in the Winter period.
In particular, the forecast of the mean sea level pressure during a stormy episode is found
to improve considerably.
A similar conclusion holds for the comparison with the more recent HIRLAM version 5.1.4,
which includes the land surface scheme ISBA, but differences in the scores are generally smaller.
A considerable diurnal oscillation in the bias of the 2 meter temperature produced by
HIRLAM with ECMWF physics and HIRLAM version 5.0.6 is found greatly reduced
in HIRLAM version 5.1.4, most likely owing the assimilation of the surface parameters that was
introduced with the land surface scheme ISBA.
Verification of 10-meter wind speeds over the southern North Sea basin show that all model
three model versions, and in particular HIRLAM with ECMWF physics, underpredict the number
of high wind speed events over sea.
Verification of upper air parameters shows comparable results among the three model versions.
Verification scores of 6-hour precipitation show that HIRLAM with ECMWF physics
is performing consistently better both in amounts of precipitation as in the occurrence of
events with either high or low amounts of precipitation.
Finally, a case study of a multi-day extreme rainfall event over parts of Italy has been conducted
to demonstrate the feasibility of HIRLAM with ECMWF physics to produce useful precipitation
forecasts at fine horizontal resolution (11 km).
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On 8 Nov 2005, 18:56.