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Total solar eclipses (TSEs) are impressive astronomical events that have attracted people's curiosity since ancient times. Their abrupt alterations to the radiation balance have stimulated studies on "eclipse meteorology," most of them documenting events in the Northern Hemisphere while only one TSE (23 November 2003) has been described over Antarctica. On 4 December 2021--just a few days before the austral summer solstice--the moon blocked the sun over the austral high latitudes, with the path of totality arching from the Weddell Sea to the Amundsen Sea, thus producing a ~2-min central TSE. In this work we present high-resolution meteorological observations from Union Glacier Camp (80°S, 83°W), the only location with a working station under totality, and South Pole station. These observations were complemented with meteorological records from 37 surface stations across Antarctica. Notably, the largest cooling (~5°C) was observed over the East Antarctic dome, where obscurity was ~85% while many sectors experienced insignificant temperature changes. This heterogenous cooling distribution, at odds with the seemingly homogeneous land surface of Antarctica, is partially captured by a simple radiative model. To further diagnose the effect of the eclipse on the surface meteorology, we ran multiple pairs of simulations (eclipse enabled and disabled) using the Weather Research and Forecasting (WRF) Model. The overall pattern and magnitude of the simulated cooling agree well with the observations and reveal that, in addition to the solar radiation deficit and cloud cover, low-level winds and the height of the planetary boundary layer are key determinants of the temperature changes and their spatial variability. [ABSTRACT FROM AUTHOR]

High surface temperatures are important in Antarctica because of their role in ice melt and sea level rise. We investigate a high temperature event in December 1989 that gave record temperatures in coastal East Antarctica between 60° and 100°E. The high temperatures were associated with a pool of warm lower tropospheric air with December temperature anomalies of >14°C that developed in two stages over the Amery Ice Shelf. First, there was near‐record poleward warm advection within an atmospheric river. Second, synoptically driven downslope flow from the interior reached unprecedented December strength over a large area, leading to strong descent and further warming in the coastal region. The coastal easterly winds were unusually deep and strong, and the warm pool was advected westwards, giving a short period of high temperatures at coastal locations, including a surface temperature of 9.3°C at Mawson, the second highest in its 66‐year record. Plain Language Summary: The Antarctic continent contains 90 percent of the world's freshwater ice, so any significant melt has serious implications for sea level rise. To date, most ice loss has occurred when warm ocean currents melt coastal ice from below. However, the higher air temperatures predicted for the coming decades are expected to increase surface melt, leading to an additional contribution to sea level rise. We present a case study of an event that occurred in coastal East Antarctica during December 1989 that illustrates how surface temperatures can rise to record levels leading to significant surface ice melt. The event unfolded in two stages. First, a narrow band of warm, moist air arrived in the coastal region from lower latitudes as an "atmospheric river", raising the temperature to a high, but not extreme level. Second, winds of record summer strength flowed from the interior of the Antarctic to the coastal region, drawing air down to lower levels of the atmosphere. This led to warming of the coastal air through compression, with it reaching 9.3°C at the Australian Mawson station, which was the second highest surface temperature in the 66‐year record. Key Points: Sustained horizontal warm advection toward the coast of East Antarctic via an atmospheric river led to marked warmingDownslope surface winds of record strength for the summer resulted in descent and adiabatic warming inland of the coastExtremely strong lower tropospheric easterly winds carried the warm air westwards leading to ice melt and record high surface temperatures [ABSTRACT FROM AUTHOR]

Because of the harsh weather conditions on the Antarctic continent, year-round observations of the lowlevel boundary layer must be obtained via automated data acquisition systems. Alexander Tall Tower! is an automatic weather station on the Ross Ice Shelf in Antarctica and has been operational since February 2011. At 30m tall, this station has six levels of instruments to collect environmental data, including temperature, wind speed and direction, relative humidity, and pressure. Data are collected at 30-, 15-, 7.5-, 4-, 2-, and 1-m levels above the snow surface. This study identifies short-term trends and provides an improved description of the lowest portion of the boundary layer over this portion of the Ross Ice Shelf for the February 2011-January 2014 period. Observations indicate two separate initiations of the winter season occur annually, caused by synoptic-scale anomalies. Sensible and latent heat flux estimates are computed using Monin-Obukhov similarity theory and vertical profiles of potential air temperature and wind speed. Over the three years, the monthly mean sensible heat flux ranges between 1 and 39 W m-2 (toward the surface) and the monthly mean latent heat flux ranges between -8 and 0 W m-2. Net heat fluxes directed toward the surface occur most of the year, indicating an atmospheric sink of energy. [ABSTRACT FROM AUTHOR]

Accurately predicting moisture and stability in the Antarctic planetary boundary layer (PBL) is essential for low-cloud forecasts, especially when Antarctic forecasters often use relative humidity as a proxy for cloud cover. These forecasters typically rely on the Antarctic Mesoscale Prediction System (AMPS) Polar Weather Research and Forecasting (Polar WRF) Model for high-resolution forecasts. To complement the PBL observations from the 30-m Alexander Tall Tower! (ATT) on the Ross Ice Shelf as discussed in a recent paper by Wille and coworkers, a field campaign was conducted at the ATT site from 13 to 26 January 2014 using Small Unmanned Meteorological Observer (SUMO) aerial systems to collect PBL data. The 3-km-resolution AMPS forecast output is combined with the global European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAI), SUMO flights, and ATT data to describe atmospheric conditions on the Ross Ice Shelf. The SUMO comparison showed that AMPS had an average 2-3 m s−1 high wind speed bias from the near surface to 600 m, which led to excessive mechanical mixing and reduced stability in the PBL. As discussed in previous Polar WRF studies, the Mellor-Yamada-Janjić PBL scheme is likely responsible for the high wind speed bias. The SUMO comparison also showed a near-surface 10-15-percentage-point dry relative humidity bias in AMPS that increased to a 25-30-percentage-point deficit from 200 to 400 m above the surface. A large dry bias at these critical heights for aircraft operations implies poor AMPS low-cloud forecasts. The ERAI showed that the katabatic flow from the Transantarctic Mountains is unrealistically dry in AMPS. [ABSTRACT FROM AUTHOR]