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This study, utilizing ERA5 data from 1979 to 2021, identifies a prevalent occurrence of blocking events in East Antarctica, particularly in the region extending from Wilkes Land to Dronning Maud Land. The genesis of these blocking highs is typically facilitated by the intensification of Rossby waves within the circumpolar westerlies. By classifying the circulation patterns causing the blocking events, the blocking events in East Antarctica are divided into five categories. On the western flank of the blocking high, we observe the transportation of warm and humid air into inland Antarctica, instigating regional snowfall. High precipitation levels are observed in different regions based on the specific location of the blocking high. We also demonstrate that the contribution of atmospheric blockings to total annual precipitation and extreme precipitation events increases from coastal to inland. Over the East Antarctic plateau, the blockings are responsible for at least 15% of total accumulated snowfall and 30% of extreme precipitation events. Finally, we find a significant relationship between the interannual variability in East Antarctic blocking frequency and the phase variability of the Southern Annular Mode (SAM). A positive phase of the SAM inhibits an increase in blocking frequency, while a negative phase favors an increase. However, the two Pacific–South American patterns (PSA-1 and PSA-2), characterized by wave trains originating in the tropical Pacific that extend across the Southern Hemisphere extratropics, do not significantly influence the interannual variability in East Antarctic blocking frequency. [ABSTRACT FROM AUTHOR]

The detection capability of the water vapor mixing ratio (q) and total precipitable water vapor (PWV) products of the Atmospheric Infrared Sounder (AIRS), the Atmospheric Vertical Sounder System (VASS), and Visible and Infrared Radiometer (VIRR) in Antarctica is unclear due to the harsh environment and the scarcity of ground‐based stations. This study compares these products with data from nine radiosonde stations and 10 Global Navigation Satellite Systems Stations and evaluates them using the CCHZ‐DISO method. In the low atmosphere, the average wet bias of about 22% of VASS q is significantly greater than that of AIRS q (<15%), and the dry bias of AIRS is gradually corrected with increasing cloudiness, but the trend of exacerbated wet bias at 700 hPa requires attention. Meanwhile, VASS should optimize the inversion principle in the presence of clouds and refine the utilization weights of the channels heavily influenced by clouds under different cloud fraction conditions. Furthermore, when the atmospheric pressure is less than 500 hPa, VASS q exhibits a significant wet bias, and these data should be used cautiously. Both AIRS and VIRR detect PWV well in coastal areas, but VIRR PWV is significantly overestimated in the dry ice sheet plateau region. The CCHZ‐DISO value intuitively reveals that AIRS outperforms VASS and VIRR in both q and PWV detection. The findings of this study contribute to a more comprehensive understanding of the detection capability of the above satellite water vapor products to promote the wider application of satellite data in the Antarctic region. Plain Language Summary: Antarctic water vapor has an important impact on global climate change, and satellites are an effective tool for comprehensively observing water vapor in the Antarctic continent. The detection capability of their water vapor products needs to be assessed. This study provides a more comprehensive assessment of the water vapor products of Atmospheric Infrared Sounder (AIRS), the Atmospheric Vertical Sounder System (VASS), and Visible and Infrared Radiometer (VIRR) and compares them using the latest CCHZ‐DISO method. The results show that AIRS, which has a hyperspectral resolution, has a better ability to detect water vapor, significantly greater than the other two instruments. This study also reveals the bias of AIRS in detecting water vapor in the lower atmosphere, the insensitivity of VASS at low water vapor content, the overestimation of VIRR in the Antarctic interior, and the inadequacy of the inversion algorithm of VASS in the presence of clouds, which will be of great help to the subsequent improvement of the satellite observation capability of Antarctic water vapor and help to understand further the important role played by Antarctic water vapor in global warming. Key Points: Long‐term, multisite, multivapor parameter comprehensive assessment of Atmospheric Infrared Sounder (AIRS), Atmospheric Vertical Sounder System (VASS), and Visible and Infrared Radiometer (VIRR) water vapor products over AntarcticaUsing the CCHZ‐DISO method, a comprehensive comparison of satellite water vapor products is performedCompared to VASS and VIRR, the greater accuracy of AIRS reflects the advantage of hyperspectral resolution in water vapor remote sensing [ABSTRACT FROM AUTHOR]

Atmospheric aerosols greatly contribute to the uncertainty in current climate models, particularly presenting pronounced limitations in the Antarctic region. This study measures aerosol properties using data from several Antarctic AERONET sites (Escudero, Marambio, South Pole, Utsteinen, Vechernaya_Hill) and Zhongshan Station. We examined the spatial and temporal patterns of two specific aerosol properties: Aerosol Optical Depth (AOD) at 500 nm (τ 500 nm) and Ångström Exponent (AE) between 440 and 870 nm (α 440 − 870 nm). Our findings reveal τ 500 nm medians ranging from 0.02 to 0.09, with elevated values observed along the coastal regions compared to the interior of Antarctica. Regarding the AE, the medians of α 440 − 870 nm indicate that the coarse-mode particle aerosols are dominated at Escudero (approximately 0.54). In contrast, fine mode particles prevail at the other sites (over 0.97). Monthly mean τ 500 nm and the proportion of fine mode particles peaks during austral summer and autumn, suggesting increased marine biological sources. Moreover, analyzing the air mass back trajectories, we discovered marine air influences on Escudero, Marambio, Zhongshan, and Vechernaya_Hill, while Utsteinen and South Pole are primarily experiencing air originating from the Antarctic continent. These findings underscore the significant role of aerosol sources in regional AOD differences. Additionally, higher τ 500 nm were more associated with significantly negative direct aerosol radiative forcing at the bottom of the atmosphere (DARF-BOA). The direct aerosol radiative forcing at the top of the atmosphere (DARF-TOA) closely correlates with single-scattering albedo (SSA), where high (low) SSA generally results in negative (positive) forcing over Antarctica. • The median AOD (500 nm) in Antarctica ranges from 0.02 to 0.09, with the coastal values higher than those inland. • During the observation period, Antarctic aerosols were dominated by fine mode particles. • Backward trajectories show that air masses from ocean and inland lead to regional AOD differences. • The absolute negative forcing of DARF-BOA increases with the increase of AOD. • High (low) SSA may lead to negative (positive) DARF-TOA over Antarctica. [ABSTRACT FROM AUTHOR]

Using ERA-Interim and output of the regional climate model MAR (Modèle Atmosphérique Régional) forced by ERA-Interim, this study investigates the mechanisms governing the persistent extreme rainfall events (PEREs) in the Antarctic Peninsula (AP) during austral summer (December–February) for the period 1980–2017. Due to the topography's blocking effect on the warm and humid airflow, the increase in the rainfall is concentrated over the western AP during the periods of the PEREs. Contributed mainly by the low-frequency variations, the positive rainfall anomalies on the western AP can persist for multiple days, leading to the persistence of the extreme rainfall events. The additional rainfall anomalies can be attributed to the increase in the total precipitation. Through regulating the total precipitation, the low-frequency atmospheric circulation anomalies are vital to the formation of the PEREs. Specifically, a persistent circulation pattern with an anomalous cyclone (anticyclone) to the east (west) of the AP is conductive to the enhancement of poleward moisture fluxes. As a result, the total precipitation around the AP is strengthened, as well as the rainfall. Further investigation reveals that the barotropic feedback of the high-frequency eddies plays an important role in maintaining the low-frequency circulation anomalies. [ABSTRACT FROM AUTHOR]

Near-surface wind speed observations from 30 manned meteorological stations and 26 automatic weather stations over the Antarctic Ice Sheet are used to examine the robustness of wind speed climatology in six recent global reanalysis products: the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), the Japan Meteorological Agency 55-Year Reanalysis (JRA-55), the Climate Forecast System Reanalysis (CFSR), the National Centers for Environmental Prediction–U.S. Department of Energy (DOE) Reanalysis 2 (NCEP2), and the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim) and fifth-generation reanalysis (ERA5). Their skills for representing near-surface wind speeds vary by season, with better performance in summer than in winter. At the regional scale, all reanalysis datasets perform more poorly for the magnitude, but better for their year-to-year changes in wind regimes in the escarpment than the coastal and plateau regions. By comparison, ERA5 has the best performance for the monthly averaged wind speed magnitude and the interannual variability of the near-surface wind speed from 1979 onward. Intercomparison exhibits high and significant correlations for annual and seasonal wind speed Antarctic-wide averages from different datasets during their overlapping timespans (1980–2018), despite some regional disagreements between the different reanalyses. Furthermore, all of the reanalyses show positive trends of the annual and summer wind speeds for the 1980–2018 period, which are linked with positive polarity of the southern annular mode. [ABSTRACT FROM AUTHOR]

Surface snow samples were collected during the 14th (1997/1998) and 24th (2007/2008) Chinese National Antarctica Research Expeditions along a transect from Zhongshan Station to Dome A. The stable oxygen isotope ratios of these samples were measured to investigate their relationships with temperature and geographical parameters (latitude, longitude, altitude and distance to the coast). The results reveal a strong positive correlation (R=0.945) between δ18 O and mean annual temperature, with a gradient of 0.84‰°C , which is a little higher than that in Terre Adelie Land. Regression analyses also show that the δ18O of surface snow is strongly correlated with distance to the coast (R=0.942), latitude (R=0.942), and altitude (R=0.941). But no significant correlation was found between δ18O and longitude in study area. Altitude should be the most important factor influencing the d O distribution because of distinctive topography. The δ18O-altitude and T-altitude gradients along this transect are determined to be -1.1‰/100 m and 1.31°C/100 m, respectively. [ABSTRACT FROM AUTHOR]

At present, continuous observation data for atmospheric nitrous oxide (N 2 O) concentrations are still lacking, especially in east Antarctica. In this paper, nitrous oxide background concentrations were measured at Zhongshan Station (69°22′25″S, 76°22′14″E), east Antarctica during the period of 2008–2012, and their interannual and seasonal characteristics were analyzed and discussed. The mean N 2 O concentration was 321.9 nL/L with the range of 320.5–324.8 nL/L during the five years, and it has been increasing at a rate of 0.29% year − 1 . Atmospheric N 2 O concentrations showed a strong seasonal fluctuation during these five years. The concentrations appeared to follow a downtrend from spring to autumn, and then increased in winter. Generally the highest concentrations occurred in spring. This trend was very similar to that observed at other global observation sites. The overall N 2 O concentration at the selected global sites showed an increasing annual trend, and the mean N 2 O concentration in the Northern Hemisphere was slightly higher than that in the Southern Hemisphere. Our result could be representative of atmospheric N 2 O background levels at the global scale. This study provided valuable data for atmospheric N 2 O concentrations in east Antarctica, which is important to study on the relationships between N 2 O emissions and climate change. [ABSTRACT FROM AUTHOR]

• Snowpack emissions due to photolysis dominate atmospheric NO 3 − production in summer. • Stratospheric inputs contribute 55±21% of atmospheric NO 3 − budget in winter. • Atmospheric NO 3 − is mainly produced via reactions of O 3 and H 2 O/OH with NO x. • Oxygen isotopes of snowfall NO 3 − are close to those for the atmosphere year-round. • Differences in δ 15 N of NO 3 − between snowfall and the atmosphere vary between seasons. Atmospheric samples and snowfall collected in coastal East Antarctica over two years are used to investigate the sources, production of atmospheric nitrate (NO 3 −) and its link with snowfall NO 3 − based upon the isotopic composition of NO 3 − (δ 15 N, δ 18 O, and Δ 17 O). Snowfall and the atmosphere show similar seasonal trends in concentrations and isotopic composition of NO 3 −. In summer, atmospheric NO 3 − is closely associated with snowpack emissions of NO x from photolysis of snow NO 3 −. In winter, linear relationships between δ 15 N and δ 18 O (or Δ 17 O) of NO 3 − in both snowfall and the atmosphere indicate mixing between stratospheric inputs and tropospheric sources contributing to NO 3 − , with stratospheric inputs contributing 55±21% of the atmospheric NO 3 − budget. The linear relationships suggest that the lower limits of δ 15 N, δ 18 O, and Δ 17 O of stratospheric-sourced NO 3 − are close to ∼18, ∼120, and ∼45‰, respectively. Concentration correlates well with the isotopic composition of NO 3 − in winter, indicating less variable contribution of tropospheric sources. A significant linear correlation between δ 18 O and Δ 17 O of NO 3 − suggests a mix of oxidation processes by O 3 and H 2 O/OH which can influence NO x cycling and the production of NO 3 −. Lower values of Δ 17 O of atmospheric NO 3 − were observed during O 3 depletion events in September, suggesting that oxygen isotopes of NO 3 − could be more sensitive to the changes in surface O 3 compared to BrO concentrations. Oxygen isotopic composition of NO 3 − in snowfall is close to that of the atmosphere throughout the year, suggesting that snowfall NO 3 − can relay information on oxidative chemistry of NO x in the atmosphere. Snowfall δ 15 N is close in value to that in the atmosphere during winter, but ∼20‰ higher than that in the atmosphere during summer, possibly associated with seasonal changes in the gas-aerosol partitioning of atmospheric NO 3 −. This suggests that the interpretation of δ 15 N in snow needs to consider seasonal changes in sources and chemistry. [ABSTRACT FROM AUTHOR]