Original paper

Analysis of the radiation budget in regional climate simulations with COSMO-CLM for Africa

Kothe, Steffen; Panitz, Hans-Jürgen; Ahrens, Bodo

Meteorologische Zeitschrift Vol. 23 No. 2 (2014), p. 123 - 141

73 references

published: Sep 1, 2014
published online: Jul 10, 2014
manuscript accepted: Mar 26, 2014
manuscript revision received: Mar 17, 2014
manuscript revision requested: Oct 23, 2013
manuscript received: Aug 15, 2013

DOI: 10.1127/0941-2948/2014/0527

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This study analysed two regional climate simulations for Africa regarding the radiation budgets with particular focus on the contribution of potentially influential parameters on uncertainties in the radiation components. The ERA-Interim driven simulations have been performed with the COSMO-CLM (grid-spacings of 0.44 ° or 0.22 °). The simulated budgets were compared to the satellite-based Global Energy and Water Cycle Experiment Surface Radiation Budget and ERA-Interim data sets. The COSMO-CLM tended to underestimate the net solar radiation and the outgoing long-wave radiation, and showed a regionally varying over- or underestimation in all budget components. An increase in horizontal resolution from 0.44 ° to 0.22 ° slightly reduced the mean errors by up to 5 %. Especially over sea regions, uncertainties in cloud fraction were the main influencing parameter on errors in the simulated radiation fluxes. Compared to former simulations the introduction of a new bare soil albedo treatment reduced the influence of uncertainties in surface albedo significantly. Over the African continent errors in aerosol optical depth and skin temperature were regionally important sources for the discrepancies within the simulated radiation. In a sensitivity test it was shown that the use of aerosol optical depth values from the MACC reanalysis product improved the simulated surface radiation substantially.


COSMO-CLMevaluationradiation budgetaerosols