Atmospheric patterns over the Antarctic Peninsula

Abstract

Using clustering analysis for the SLP field of the ERA Interim reanalysis between 1979 and 2016, five synoptic pressure patterns have been obtained for Drake area and Antarctic Peninsula (AP) region (45°S 75°S 20°W 120°W) and the resulting daily series has been made available to the scientific community. The five patterns have been named according their most important features as Low over the Weddell Sea (LWS), Low over the Amundsen and Bellingshausen Seas (LAB), Low over the Drake Passage (LDP), Zonal over the Drake Passage (ZDP) and Ridge over the Antarctic Peninsula (RAP). Each atmospheric pattern has been described after analyzing their development and evolution. A frequency analysis shows that the 5 atmospheric patterns present a similar annual frequency but a large seasonal variability. Their transitions from one to other pattern tends to follow a cycle in which synoptic atmospheric waves displaces eastwards a quarter-wavelength. Four of the five atmospheric patterns (except RAP) are very influenced by SAM, only LAB and LWS are influenced to some degree by ENSO. Occurrence of LAB pattern presents a positive trend showing agreement with other studies that indicates an enhancement of the Amundsen-Bellingshausen Sea Low. Finally, atmospheric circulation patterns have been related with the airmass advection and precipitation in Livingston Island showing the potential application to study the changes in the surface mass balance on the AP cryosphere.