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Extra‐tropical cyclones are a relevant feature in the climate at middle and high latitudes. Despite their importance, most studies typically focus only on cyclones identified at a single atmospheric level and on events close to the surface. This paper provides a new perspective on the Southern Hemisphere (SH) cyclone events based on the multilevel cyclone tracking algorithm STACKER. The algorithm, using relative vorticity, detects the raw tracks at single levels and objectively combines them to provide the 3D events and their evolutionary timeline. As a result, a 3D cyclone climatology, based on ECMWF Reanalysis ERA‐I data from 12 pressure levels in the troposphere and lowermost stratosphere is presented. To the best of our knowledge, this is the first analysis carried out throughout the troposphere and the lowermost extratropical/subpolar stratosphere in order to give a comprehensive picture of the cyclone events as physical entities throughout their lifetime. Cyclone properties analysed are track densities, translational velocity, vorticity and lifetimes. For the subtropical and extra‐tropical SH, results support many previous ideas about cyclone characteristics, but new insights are also obtained. A total of 58,231 multilevel cyclone events lasting at least 2 days were detected, with vertical structures spanning two or more levels. This means an average of 303 cyclone events of all types per month, between 2001 and 2017, disregarding seasonality. Results show that cyclones are most frequently detected at the lowest levels of 925 and 700 hPa. By considering that cyclonic systems can be grouped into families according to their vertical extent, results per month on average show that shallow systems are the most frequent events with approximately 248 systems detected, followed by 43 intermediary and 11 deep events. Shallow and deep systems have a large percentage of events with genesis at 925 and 700 hPa. Density statistics show that shallow events are present at all latitude ranges mostly poleward of 30°S with high‐ and medium‐intensities, while intermediate ones are mostly restricted to mid‐latitudes and deep events are mostly confined to sub‐polar and polar latitudes. Cyclones over Antarctica seem to be mostly intermediary and deep cyclones, with longer lifetimes and lower velocities. [ABSTRACT FROM AUTHOR]

This paper quantifies the potential benefit of limiting the global warming to 1.5°C above the preindustrial level on the high‐latitude climate of the Southern Hemisphere compared to 2.0°C and above. A set of Coupled Model Intercomparison Project Phase 5 global climate model experiments is used in order to determine the mean projected changes in surface air temperature, sea level pressure, surface winds and sea ice distribution over and around Antarctica. Alongside, changes in selected variables related to extremes (such as the annual number of extremely cold mornings and extremely cold days) are also quantified as a function of the Representative Concentration Pathway (RCP) considered reaching the given warming threshold. Physical mechanisms for the projected variations in sea ice are proposed, including surface air temperature, changes in low‐level air temperature advection and meridional winds. Results show that there would be significant differences in the atmospheric and sea ice variable changes depending on the warming threshold and RCP considered, and that indeed keeping the global warming under 1.5°C could have a noticeable impact particularly on the distribution of sea ice over the Southern Ocean. [ABSTRACT FROM AUTHOR]

ABSTRACT The first climatology of strong wind events ( SWEs) at McMurdo station, Antarctica based on the in situ observations and reanalysis fields is presented. SWEs occur throughout the year, but with a minimum during the summer. They are associated with negative mean sea level pressure ( MSLP) and upper height anomalies across the Ross Sea/Ice Shelf, as well as positive temperature anomalies at the station. Wind directions during SWEs exhibit a bimodal distribution of 135-180° and 45-90°. This distribution occurs because of the interaction of the predominantly southerly flow with the orography of Black and White Island and Minna Bluff. The east-northeast flow is associated with winds that are deflected around the orography, while the more southerly events have sufficient energy to override the barriers. The bimodal wind distribution is most common during the winter season since the southerly flow is stronger as a result of deeper cyclonic systems. SWEs also occur when there are large, positive MSLP anomalies at McMurdo station as ridges of high pressure build from the interior and enhance the pressure gradient between the continental high and offshore lows. The interannual variability in the number of winter SWEs is large. Years with many SWEs are associated with a deep climatological low centred over the north eastern Ross Ice Shelf. Years with few winter SWEs have a weakened mid-tropospheric vortex over the Ross Ice Shelf. There are periods when the index of the El Niño-Southern Oscillation ( ENSO) correlates with the number of SWEs. However, the links are not statistically significant in the longer term. A similar link was also observed between the Southern Annular Mode ( SAM) and the interannual variability in the number of SWEs. The relationship was found to be stronger when the phase of ENSO and the SAM were the same. [ABSTRACT FROM AUTHOR]

The article offers information on half-century seasonal relationships between the Southern Hemisphere Annular Mode (SAM) and Antarctic temperatures. It is posed that a general pattern of positive correlations between the strength of the SAM and temperatures in the northern Antarctic Peninsula (East Antarctica) is manifested to be valid for the last half-century, but differences are noted between the seasons. Moreover, SAM-temperature correlations are stronger across Antarctica in austral summer and autumn.

This article reports on the environmental and climatic changes and their causes in the Antarctic and Arctic. It discusses that there are continuing increases in surface temperatures, losses of sea ice and tundra, as well as warming of permafrost over areas of the Arctic, while most of the major increase in Antarctic temperatures is on the Antarctic Peninsula linked with sea ice loss in the Bellingshausen-Amundsen Seas sector. The synthesis of observational evidence leads to the conclusion that the Arctic changes of the past several decades are attributable to circulation-driven changes.

The article investigates the surface temperature changes over different land surface vegetation classes by the dividing the globe into seven regions using a global land cover classification data set. The authors also examine the detection and attribution of surface temperature trends over various vegetation classes for the last 50 years using outputs from three coupled climate models. Findings of the study indicate significant warming in all regions from the year 1900 and antropogenic warming trend in six out of seven regions.