Using NWP to assess the influence of the Arctic atmosphere on mid-latitude weather and climate

• Published in: Advances in Atmospheric Sciences
• Main Authors: Semmler, Tido, Jung, Thomas, Kasper, Marta A., Serrar, Soumia
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: SCIENCE CHINA PRESS 2018
• Subjects: Arctic; Kara Sea; Pacific; North Atlantic
• Online Access: https://epic.awi.de/id/eprint/45223/; https://epic.awi.de/id/eprint/45223/1/relaxation_paper_surfpar.pdf; http://159.226.119.58/aas/EN/10.1007/s00376-017-6290-4; https://hdl.handle.net/10013/epic.51422; https://hdl.handle.net/10013/epic.51422.d001

The influence of the Arctic atmosphere on Northern Hemisphere mid-latitude 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 mid-latitude 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 mid-latitude 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 mid-latitude benefits of improved Arctic prediction capabilities.