scholarly journals On the Drivers of Temperature Extremes on the Antarctic Peninsula During Austral Summer

2021 ◽  
Author(s):  
Sai Wang ◽  
Minghu Ding ◽  
Ge Liu ◽  
Ting Wei ◽  
Wenqian Zhang ◽  
...  
Keyword(s):  
Air Temperature ◽  
Antarctic Peninsula ◽  
Rossby Wave ◽  
Austral Summer ◽  
Polar Front ◽  
Temperature Extremes ◽  
Cold Events ◽  
Wave Trains ◽  
The Antarctic ◽  
Polar Front Jet

Abstract On the basis of surface air temperature (SAT) observations from the Great Wall Station located on the Antarctic Peninsula (AP) and ERA-Interim reanalysis data, the present manuscript investigates the role of atmospheric flow at intraseasonal and synoptic time scales in driving the temperature extremes over the AP during austral summer. Both warm and cold events can persist for multiple days and were maintained mainly by the advection of seasonal air temperature by intraseasonal winds. Synoptic winds can influence the temperature change around the peak time through their advection of seasonal temperature, thus determining the time of peak temperature anomalies. The generation of intraseasonal winds was closely associated with Rossby wave trains propagating along the polar front jet over the Atlantic sector of the Southern Ocean before the warm and cold events. The synoptic height anomalies before the warm events were also manifested as Rossby wave trains propagating along the polar front jet. However, synoptic Rossby wave trains were almost absent when the cold events occurred. Further analysis indicates that the weakened background flow during the cold events may have hindered the eastward travel of synoptic eddies. This study provides an important guidance for subseasonal to seasonal prediction on the AP.

scholarly journals An Assessment of ERA5 Reanalysis for Antarctic Near-Surface Air Temperature

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 217
Author(s):  
Jiangping Zhu ◽  
Aihong Xie ◽  
Xiang Qin ◽  
Yetang Wang ◽  
Bing Xu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Antarctic Peninsula ◽  
Austral Summer ◽  
Correlation Coefficients ◽  
East Antarctica ◽  
West Antarctica ◽  
Austral Spring ◽  
Reanalysis Dataset ◽  
Near Surface ◽  
The Antarctic

The European Center for Medium-Range Weather Forecasts (ECMWF) released its latest reanalysis dataset named ERA5 in 2017. To assess the performance of ERA5 in Antarctica, we compare the near-surface temperature data from ERA5 and ERA-Interim with the measured data from 41 weather stations. ERA5 has a strong linear relationship with monthly observations, and the statistical significant correlation coefficients (p < 0.05) are higher than 0.95 at all stations selected. The performance of ERA5 shows regional differences, and the correlations are high in West Antarctica and low in East Antarctica. Compared with ERA5, ERA-Interim has a slightly higher linear relationship with observations in the Antarctic Peninsula. ERA5 agrees well with the temperature observations in austral spring, with significant correlation coefficients higher than 0.90 and bias lower than 0.70 °C. The temperature trend from ERA5 is consistent with that from observations, in which a cooling trend dominates East Antarctica and West Antarctica, while a warming trend exists in the Antarctic Peninsula except during austral summer. Generally, ERA5 can effectively represent the temperature changes in Antarctica and its three subregions. Although ERA5 has bias, ERA5 can play an important role as a powerful tool to explore the climate change in Antarctica with sparse in situ observations.

Behaviour and dive times of Arnoux's beaked whales, Berardius arnuxii, at narrow leads in fast ice

1996 ◽  
Vol 74 (2) ◽  
pp. 388-393 ◽  
Author(s):  
R. P. Hobson ◽  
A. R. Martin
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Austral Summer ◽  
Food Resources ◽  
Breath Hold ◽  
Beaked Whale ◽  
Horizontal Movement ◽  
Beaked Whales ◽  
Fast Ice ◽  
The Antarctic

Groups of the little-known Arnoux's beaked whale, Berardius arnuxii, were observed at narrow cracks or leads in sea ice near the Antarctic peninsula during the austral summer of 1992–1993. The whales were grey, had a slightly asymmetric blowhole and blow, and were heavily scarred in adulthood. At least 30 animals were uniquely identified using their scars. Despite often cramped conditions at the breathing holes, the whales were always calm and nonaggressive, reacting to the circumstances with surfacing and submerging behaviour involving little horizontal movement. Seventy dive durations by 17 identified adults were recorded, with a mode of 35–65 min and a maximum of at least 70 min. Eight periods of respiration varied between 1.2 and 6.8 min, with an average of 9.6 blows/min. These breath-hold characteristics confirm B. arnuxii as one of the most accomplished mammalian divers, capable of swimming up to an estimated 7 km between breathing sites in sea ice. Whales moved to and from the observed lead, apparently able to find other breathing sites in what appeared to be unbroken ice. The species seems well adapted to life in ice-covered waters and may be able to exploit food resources inaccessible to other predators in the region.

scholarly journals The AEMET-<i>γ</i>SREPS over the Antarctic Peninsula and the impact of kilometric-resolution EPS on logistic activities on the continent

2020 ◽  
Vol 17 ◽  
pp. 209-217
Author(s):  
Sergi Gonzalez ◽  
Alfons Callado ◽  
Mauricia Martínez ◽  
Benito Elvira
Keyword(s):  
Boundary Conditions ◽  
Antarctic Peninsula ◽  
Positive Impact ◽  
Austral Summer ◽  
Added Value ◽  
Ensemble Prediction ◽  
Prediction Systems ◽  
Nwp Model ◽  
The Antarctic ◽  
The Impact

Abstract. Kilometric-resolution Ensemble Prediction Systems (EPSs) will be the new state-of-the-art forecasting tools for short-range prediction in the following decade. Their value will be even greater in Antarctica due to the increasingly demanding weather forecasts for logistic services. During the 2018–2019 austral summer (1 December–31 March), coinciding with the Southern Hemisphere Special Observation Period of the Year of Polar Prediction (YOPP), the 2.5 km AEMET-γSREPS was operationally integrated over the Antarctic Peninsula. In particular, the Antarctic version of γSREPS comes up with crossing four non-hydrostatic convection-permitting NWP models at 2.5 km with three global NWP driving models as boundary conditions. The γSREPS forecasting system has been validated in comparison with ECMWF EPS. It is concluded that γSREPS has an added value to ECMWF EPS due to both its higher resolution and its multi-boundary conditions and multi-NWP model approach. γSREPS performance has a positive impact on logistic activities at research stations and its design may contribute to polar prediction research.

Global Perspective of the Quasi-Biweekly Oscillation*

2009 ◽  
Vol 22 (6) ◽  
pp. 1340-1359 ◽  
Author(s):  
Kazuyoshi Kikuchi ◽  
Bin Wang
Keyword(s):  
Central America ◽  
Rossby Wave ◽  
Austral Summer ◽  
Global Perspective ◽  
Asia Pacific ◽  
Boreal Summer ◽  
Mean Flow ◽  
Wave Trains ◽  
Mean Climate ◽  
Long Term Observation

Abstract The quasi-biweekly oscillation (QBW: here defined as a 12–20-day oscillation) is one of the major systems that affect tropical and subtropical weather and seasonal mean climate. However, knowledge is limited concerning its temporal and spatial structures and dynamics, particularly in a global perspective. To advance understanding of the QBW, its life cycle is documented using a tracking method and extended EOF analysis. Both methods yield consistent results. The analyses reveal a wide variety of QBW activity in terms of initiation, movement, development, and dissipation. The convective anomalies associated with the QBW are predominant in the latitude bands between 10° and 30° in both hemispheres. The QBW modes tend to occur regionally and be associated with monsoons. Three boreal summer modes are identified in the Asia–Pacific, Central America, and subtropical South Pacific regions. Five austral summer modes are identified in the Australia–southwest Pacific, South Africa–Indian Ocean, South America–Atlantic, subtropical North Pacific, and North Atlantic–North Africa regions. The QBW modes are classified into two categories: westward- and eastward-propagating modes. The westward mode is found in the Asia–Pacific and Central America regions during boreal summer; it originates in the tropics and dissipates in the subtropics. The behavior of the westward-propagating mode can be understood in terms of equatorial Rossby waves in the presence of monsoon mean flow and convective coupling. The eastward-propagating mode, on the other hand, connects with upstream extratropical Rossby wave trains and propagates primarily eastward and equatorward. Barotropic Rossby wave trains play an essential role in controlling initiation, development, and propagation of the eastward QBW mode in the subtropics. The results therefore suggest that not only tropical but also extratropical dynamics are required for fully understanding the behavior of the QBW systems worldwide. The new conceptual picture of QBW obtained here based on long-term observation provides valuable information on the behavior of QBW systems in a global perspective, which is important for a thorough understanding of tropical variability on a time scale between day-to-day weather and the Madden–Julian oscillation.

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