The role of vortex weakening on Antarctic Peninsula cooling in recent decades
Abstract
In contrast to the overall rapid warming over the Antarctic Peninsula (AP) for the past 50 years, there has been a cooling trend since 1999. The temperature observed at the King Sejong station in the King George Island off the AP since 1989 also shows the cooling trend. The cooling trend found in the AP is reported to be caused by a shift in cyclonic center to the Drake Passage and the Weddell Sea, that brings about cold air from the east to the AP. The shift of the cyclonic center to the east is associated with the change in ENSO indices. In this study, we investigate the role of polar vortex on the AP cooling. Because the sudden stratospheric warming event is rare in the southern hemisphere associated with too strong southern stratospheric polar vortex (SSPV), we devised a criterion to quantify weaker SSPV event using polar cap height anomaly. Since 2000, in fact, the weaker SSPV in the Southern Hemisphere has occurred more frequently during spring, especially in October. When there is weaker SSPV event, surface temperature in the AP tends to be colder than normal, whereas warmer in the rest of Antarctica, as a reminiscent of negative phase of Southern Annular Mode. According to daily temperature records measured at the King Sejong station, the cold anomaly persists for about three months after the onset of the SSPV. The higher height anomaly in stratosphere propagates down to the surface from November to January following year, leading to the cold anomaly in the AP region. The daily polar cap height anomalies also have increasing trend toward present, consistent with the more frequent occurrence of the weaker SSPV events. The more frequent weaker SSPV events since 2000 seem to play some role in the AP cooling.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A43C..08K
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3339 Ocean/atmosphere interactions;
- ATMOSPHERIC PROCESSESDE: 3364 Synoptic-scale meteorology;
- ATMOSPHERIC PROCESSESDE: 1621 Cryospheric change;
- GLOBAL CHANGE