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[ACC38-02] Effect of snow impurities on albedo observed during 8 winter seasons in Sapporo
Comparing the time series of the observed albedo and the model calculated value in each year of the analysis period, it is found that the simulated albedo variations due to the change in snow grain size and impurity concentration agreed well with the observations. The determination coefficient (R2) and the root mean square error (RMSE) in the whole period obtained from the albedo comparison between the observation and the calculation in the shortwave (SW) region were 0.831 and 0.045, respectively, confirming the high accuracy of PBSAM. Next, sensitivity experiments were conducted on albedo changes in the visible (VIS), near-infrared (NIR), and SW regions depending on the presence or absence of snow impurities which consist of black carbon (BC) and mineral dust. The albedo change due to snow impurities (BC + dust) in the whole period was -0.085 in the VIS region, -0.016 in the NIR region, and -0.053 in the SW region. We also investigated the contributions from BC and dust to the total SW albedo change, which were -0.043 and -0.009 by BC and dust, respectively. In addition, the ratio in SW albedo change during accumulation period and melting period (melting period / accumulation period) was 4.1 times for BC, 12.0 times for dust, and 4.9 times for BC + dust.
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