Implementation of a simple thermodynamic sea ice scheme, SICE version 1.0-38h1, within the ALADIN–HIRLAM numerical weather prediction system version 38h1
<p>Sea ice is an important factor affecting weather regimes, especially in polar regions. A lack of its representation in numerical weather prediction (NWP) systems leads to large errors. For example, in the HARMONIE–AROME model configuration of the ALADIN–HIRLAM NWP system, the mean absolu...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-08-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/11/3347/2018/gmd-11-3347-2018.pdf |
| Summary: | <p>Sea ice is an important factor affecting weather regimes, especially in polar
regions. A lack of its representation in numerical weather prediction (NWP)
systems leads to large errors. For example, in the HARMONIE–AROME model
configuration of the ALADIN–HIRLAM NWP system, the mean absolute error in
2 m temperature reaches 1.5 °C after 15 forecast hours for
Svalbard. A possible reason for this is that the sea ice properties are not
reproduced correctly (there is no prognostic sea ice temperature in the
model). Here, we develop a new simple sea ice scheme (SICE) and implement it
in the ALADIN–HIRLAM NWP system in order to improve the forecast quality in
areas influenced by sea ice. The new parameterization is evaluated using
HARMONIE–AROME experiments covering the Svalbard and Gulf of Bothnia areas
for a selected period in March–April 2013. It is found that using the SICE
scheme improves the forecast, decreasing the value of the 2 m temperature
mean absolute error on average by 0.5 °C in areas that are
influenced by sea ice. The new scheme is sensitive to the representation of
the form drag. The 10 m wind speed bias increases on average by
0.4 m s<sup>−1</sup> when the form drag is not taken into account. Also, the
performance of SICE in March–April 2013 and December 2015–December 2016 was
studied by comparing modelling results with the sea ice surface temperature
products from MODIS and VIIRS. The warm bias (of approximately 5 °C)
of the new scheme is indicated for areas of thick ice in the Arctic. Impacts
of the SICE scheme on the modelling results and possibilities for future
improvement of sea ice representation in the ALADIN–HIRLAM NWP system are
discussed.</p> |
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| ISSN: | 1991-959X 1991-9603 |