How does large-scale nudging in a regional climate model contribute to improving the simulation of weather regimes and seasonal extremes over North America?

摘要: To determine the extent to which regional climate models (RCMs) preserve large-scale atmospheric circulation of their driving fields, we investigate ability two RCM simulations reproduce weather regimes over North America. Each simulation is driven at its lateral boundaries by ERA-Interim reanalysis, but one them uses additional nudging (LSN) in domain interior. Four describing variability dynamics America are identified winter and summer. The analysis shows that for both seasons, mean frequency occurrence persistence four comparable those ERA-Interim. However, false daily attributions a specific regime on day-to-day seasonal bases significantly high, especially summer, classic lateral-boundary simulation. Those largely corrected with LSN. Using composite means each regimes, substantial 2-m air temperature precipitation anomalies associated found. These larger than validation reveals bias dependent Conversely, varies from another, winter. Overall, results suggest simulates statistics well, LSN necessary match field.