The HIRLAM fast radiation scheme for mesoscale numerical weather prediction models
| Autor: | Petri Räisänen, Hannu Savijärvi, Laura Rontu, Bent Hansen Sass, Kristian Pagh Nielsen, Emily Gleeson |
|---|---|
| Přispěvatelé: | Department of Physics |
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Atmospheric Science
PARAMETERIZATION 010504 meteorology & atmospheric sciences Meteorology Cloud cover 0208 environmental biotechnology Mesoscale meteorology CLIMATE MODELS 02 engineering and technology lcsh:QC851-999 Atmospheric sciences 01 natural sciences 114 Physical sciences CLOUD PARTICLES VERIFICATION EFFECTIVE SIZES lcsh:Science Physics::Atmospheric and Oceanic Physics 0105 earth and related environmental sciences Ensemble forecasting NWP SYSTEM Ecological Modeling SURFACE RADIATION Longwave OPTICAL-PROPERTIES Numerical weather prediction Pollution lcsh:QC1-999 WATER CLOUDS 020801 environmental engineering SOLAR-RADIATION Geophysics 13. Climate action Environmental science Climate model lcsh:Q lcsh:Meteorology. Climatology Shortwave HIRLAM lcsh:Physics |
| Zdroj: | Advances in Science and Research, Vol 14, Pp 195-215 (2017) |
| ISSN: | 1992-0636 |
| Popis: | This paper provides an overview of the HLRADIA shortwave (SW) and longwave (LW) broadband radiation schemes used in the HIRLAM numerical weather prediction (NWP) model and available in the HARMONIE-AROME mesoscale NWP model. The advantage of broadband, over spectral, schemes is that they can be called more frequently within the model, without compromising on computational efficiency. In mesoscale models fast interactions between clouds and radiation and the surface and radiation can be of greater importance than accounting for the spectral details of clear-sky radiation; thus calling the routines more frequently can be of greater benefit than the deterioration due to loss of spectral details. Fast but physically based radiation parametrizations are expected to be valuable for high-resolution ensemble forecasting, because as well as the speed of their execution, they may provide realistic physical perturbations. Results from single-column diagnostic experiments based on CIRC benchmark cases and an evaluation of 10 years of radiation output from the FMI operational archive of HIRLAM forecasts indicate that HLRADIA performs sufficiently well with respect to the clear-sky downwelling SW and longwave LW fluxes at the surface. In general, HLRADIA tends to overestimate surface fluxes, with the exception of LW fluxes under cold and dry conditions. The most obvious overestimation of the surface SW flux was seen in the cloudy cases in the 10-year comparison; this bias may be related to using a cloud inhomogeneity correction, which was too large. According to the CIRC comparisons, the outgoing LW and SW fluxes at the top of atmosphere are mostly overestimated by HLRADIA and the net LW flux is underestimated above clouds. The absorption of SW radiation by the atmosphere seems to be underestimated and LW absorption seems to be overestimated. Despite these issues, the overall results are satisfying and work on the improvement of HLRADIA for the use in HARMONIE-AROME NWP system is ongoing. In a HARMONIE-AROME 3-D forecast experiment we have shown that the frequency of the call for the radiation parametrization and choice of the parametrization scheme makes a difference to the surface radiation fluxes and changes the spatial distribution of the vertically integrated cloud cover and precipitation. |
| Databáze: | OpenAIRE |
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