the numerical sea ice forecast in finland in the winter 1993-94 ...

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3.4. Statistical verification
An objective verification procedure was used in order to check the forecast results and to make an
objective assessment of the model. Root mean square error (RMSE) of ice thickness and mean error
(ME) of the ice edge was estimated for trial and numerical forecasts. The real ice edge was taken from
ERS-1 imagery and the forecasted ice edge was defined as a 4 cm isoline in the thickness field. In the
table 1 and figures 6-7 the statistical verification is given for February 23 - May 18 1994. The RMSE
for ice thickness was 8 cm and ME for ice edge 6 km for a 24 h forecast during the forcasted 85 days.
4. CONCLUSIONS
On comparation and verification of the numerical ice model rather satisfactory results can be seen.
After all, this was the first time that the new Baltic Sea sea ice model was running over such a long
period. There is, however, a large amount of development to be done in the future. Most of all, the
forecasting period must be prolonged from 36 h into >72 h. The next step Will be improving the
accuracy of the initial ice field, and linking the model into a weather prediction model. Another field
Will be to perfect the forecasting results by using a coupled sea ice - ocean model.
REFERENCES
Grönvall, H. 1988: Finnish ice service. - Finnish Marine Research No 256:95-110.
Leppäranta, M. 198 1: An ice drift model for the Baltic Sea. - Tehus 33 (6):583-596.
Seinä, A. 1994: Extent of ice-cover 1961-1990 and restrictions to navigation 198 1 - 1990 along the
Finnish coast. - Finnish Marine Research No 262:3-34.
Wu, Huiding & Leppäranta, M. 1990: Experiments on numerical sea ice forecasting in the Bohai Sea.
- Proc. on the IAHR Symposium on Ice, Espoo, Finland, Aug. 20-24 1990. Vol. 3: 173-186.
Wu, Huiding; Zhang, Zhanhai & Bai, Shan 1993: On the operational numerical forecast of sea ice in
the Bohai Bay of China.
numerical initial
numerical ice forecast products
e.g. thickness, toncentration,
ridges, ice floating field,
ice edge
I
USERS
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Fig. 2. Flow chart of the numerical forecast system