The influence of the Arctic atmosphere on Northern Hemisphere midlatitude tropospheric weather and climate is explored
by comparing the skill of two sets of 14-day weather forecast experiments using the ECMWF model with and without
relaxation of the Arctic atmosphere towards ERA-Interim reanalysis data during the integration. Two pathways are identified
along which the Arctic influences midlatitude weather: a pronounced one over Asia and Eastern Europe, and a secondary
one over North America. In general, linkages are found to be strongest (weakest) during boreal winter (summer) when the
amplitude of stationary planetary waves over the Northern Hemisphere is strongest (weakest). No discernible Arctic impact
is found over the North Atlantic and North Pacific region, which is consistent with predominantly southwesterly flow. An
analysis of the flow-dependence of the linkages shows that anomalous northerly flow conditions increase the Arctic influence
on midlatitude weather over the continents. Specifically, an anomalous northerly flow from the Kara Sea towards West Asia
leads to cold surface temperature anomalies not only over West Asia but also over Eastern and Central Europe. Finally, the
results of this study are discussed in the light of potential midlatitude benefits of improved Arctic prediction capabilities

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• Using NWP to Assess the Influence of the Arctic Atmosphere on Midlatitude Weather and Climate