Atmospheric Patterns over the Antarctic Peninsula

Abstract

Using clustering analysis for the sea level pressure field of the ERA-Interim reanalysis between 1979 and 2016, five synoptic pressure patterns have been obtained for the Drake area and Antarctic Peninsula (AP) region (45°–75°S, 20°–120°W), and the resulting daily series has been made available to the scientific community. The five patterns have been named according to their most important features as follows: low over the Weddell Sea (LWS), low over the Amundsen and Bellingshausen Seas (LAB), low over the Drake Passage (LDP), zonal flow over the Drake Passage (ZDP), and ridge over the Antarctic Peninsula (RAP). Each atmospheric pattern is described after analyzing its development and evolution. A frequency analysis shows that the five atmospheric patterns present a similar annual frequency but a large seasonal variability. The transitions from one pattern to another tend to follow a cycle in which synoptic atmospheric waves are displaced eastward by a quarter wavelength. Four of the five atmospheric patterns (all except RAP) are very influenced by the southern annular mode (SAM); however, only LAB and LWS are influenced to some degree by ENSO. The occurrence of the LAB pattern presents a positive trend showing agreement with other studies that indicate an enhancement of the Amundsen–Bellingshausen Seas low. Finally, atmospheric circulation patterns have been related to the airmass advection and precipitation in Livingston Island, showing the potential application for studying the changes in the surface mass balance on the AP cryosphere.

Multi‐year assessment of atmospheric circulation and impacts on air temperature variation on James Ross Island, Antarctic Peninsula

“…Patterns contained within other classifications, for example, Gonzales et al . (), can be found in the presented classification, even though the “Antarctic wedge” (Govorukha and Timofeyev, ) is only represented in synoptic pattern [4, 3], where it forms a blocking system to cyclonic activity.…”

“…() and Gonzales et al . (), according to whom the Amundsen–Bellingshausen Sea Low is deeper during the La Niña phase. The positive correlation of the synoptic pattern [1, 3] explains the decrease of this synoptic pattern in 2010 and 2011 (Figure ) when ENSO was in its negative phase (La Niña).…”

“…The number of synoptic patterns in this study is larger than was proposed by Gonzales et al . (), but the self‐organizing maps algorithm enables subtle differences to be distinguished, such as the relative depth of a cyclone on the expanse of less common synoptic patterns. Patterns contained within other classifications, for example, Gonzales et al .…”

“…Frequencies of occurrence were consistent with those reported by Gonzales et al . () if the synoptic patterns in this study were grouped.…”

“…However, the histogram shifted from a centre between −2 and 0°C in summer to an interval of −20 and −14°C, which explains the uniformity of the entire annual distribution. These results are consistent with the influence of atmospheric circulation on air temperature in the South Shetland Islands (Kejna and Láska, ; Braun et al ., ; Gonzales et al ., ). The change in the seasonal distributions might also be connected to changes in the positions of the circumpolar trough around Antarctica (Simmonds et al ., ) and Amundsen–Bellingshausen Sea Low (Turner et al ., ), hence the variation in direction and coldness of advected air masses within these synoptic patterns.…”