Black carbon concentration and deposition estimations in Finland by the regional aerosol-climate model REMO-HAM
The prediction skill of the regional aerosol-climate model REMO-HAM was\nassessed against the black carbon (BC) concentration measurements from\nfive locations in Finland, with focus on Hyytiala station for the year\n2005. We examined to what extent the model is able to reproduce the\nmeasurements using several statistical tools: median comparison, overlap\ncoefficient (OVL; the common area under two probability distributions\ncurves) and Z score (a measure of standard deviation, shape and spread\nof the distributions). The results of the statistics showed that the\nmodel is biased low. The local and regional emissions of BC have a\nsignificant contribution, and the model tendency to flatten the observed\nBC is most likely dominated by the lack of domestic burning of biofuel\nin the emission inventories. A further examination of the precipitation\ndata from both measurements and model showed that there is no\ncorrelation between REMO's excessive precipitation and BC\nunderestimation. This suggests that the excessive wet removal is not the\nmain cause of the low black carbon concentration output. In addition, a\ncomparison of wind directions in relation with high black carbon\nconcentrations shows that REMO-HAM is able to predict the BC source\ndirections relatively well. Cumulative black carbon deposition fluxes\nover Finland were estimated, including the deposition on snow.