Editing IPCC:AR6/WGI/Chapter-Atlas (section)

===== Atlas.11.1.1.1 Key Features of the Regional Climate =====

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The Antarctic region, covered by an ice sheet and surrounded by the Southern Ocean, is characterized by polar climate. It is the coldest, windiest and driest continent on Earth and plays a pivotal role in regulating the global climate and hydrological cycle. Antarctica has a mean temperature of –35°C ( [[#Lenaerts--2016|Lenaerts et al., 2016]] ) and receives 171 mm yr <sup>–1</sup> water equivalent of snowfall (north of 82°S, estimate based on satellite measurements during 2006–2011; [[#Palerme--2014|Palerme et al., 2014]] ). Precipitation in Antarctica occurs mostly in the form of snowfall and diamond dust, with sporadic coastal rainfall during the summer over the Antarctic Peninsula and sub-Antarctic islands. Drizzle events sometimes occur during warm air intrusions ( [[#Nicolas--2017|Nicolas et al., 2017]] ) at relatively low temperatures ( [[#Silber--2019|Silber et al., 2019]] ). Precipitation constitutes the largest component of the surface mass balance (SMB) '','' which also includes sublimation (from the surface or drifting snow), meltwater runoff and redistribution by wind ( [[#Lenaerts--2019|Lenaerts et al., 2019]] ). SMB can be considered as a proxy of precipitation if averaged over an annual cycle ( [[#Gorodetskaya--2015|Gorodetskaya et al., 2015]] ; [[#Bracegirdle--2019|Bracegirdle et al., 2019]] ). Precipitation and SMB exhibit spatial and temporal variability controlled by atmospheric large-scale low-pressure systems and moisture advection from lower latitudes. SMB is an important component of the total ice-sheet mass balance ( [[IPCC:Wg1:Chapter:Chapter-9#9.4.2.1|Section 9.4.2.1]] ). The Antarctic contribution to sea level results from the imbalance between net snow accumulation and ice discharge into the ocean (Box 9.1). Ice shelves buttress the ice sheet and are influenced by oceanic and atmospheric drivers (Box 9.1).

Antarctic climate variability is influenced by the Southern Annular Mode (SAM) and regionally by other modes, including ENSO, Pacific–South American pattern, Pacific Decadal Variability (PDV), Indian Ocean Dipole and Zonal Wave 3 (Annex IV). Climate change in Antarctica and the Southern Ocean is influenced by interactions between the ice sheet, ocean, sea ice and atmosphere (Sections 9.2.3.2, 9.3.2 and 9.4.2; [[#Meredith--2019|Meredith et al., 2019]] ). In addition to Chapter 9, Antarctica is discussed across the report: global climate links (Chapters 2 and 10), attribution (Chapter 3), global water cycle (Chapter 8), extremes (Chapter 11), and climatic impact-drivers (Chapter 12).

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