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Sea ice is important for both regional and global climate, but comprehensive sea ice records are lacking pre-1978, when global-scale spaceborne observations began. Attempts to reconstruct sea ice conditions in different regions of Antarctica with the help of methane sulphonic acid (MSA) records from ice cores have had varying success, highlighting the often-regional relationship between ice core MSA and sea ice. This study uses MSA records from three firn cores and one ice core drilled on Fimbul Ice Shelf in Dronning Maud Land, East Antarctica, to investigate the relationship to satellite-derived sea ice extent (SIE) in the Southern Ocean. Chlorophyll-a concentrations, serving as a measure of phytoplankton biomass, are correlated to the MSA records to further test the MSA – SIE relationship. The relationship to both SIE and chlorophyll-a differs largely between the different firn and ice core MSA records. We find significant correlations for the MSA records from the two higher accumulation core sites to SIE and chlorophyll-a in the Weddell Sea, Western Pacific Ocean, and Ross Sea Sectors. Furthermore, the use of stacked MSA records introduced significant correlations between MSA from the lower accumulation core sites and SIE. The absence of coherent correlation patterns between the MSA records across the four investigated cores and SIE or chlorophyll-a in the Southern Ocean suggests that the Fimbul Ice Shelf MSA records are not consistent proxies for regional SIE. [ABSTRACT FROM AUTHOR]

A 25‐year set of daily radiosonde data was used to investigate temperature and humidity inversions at Neumayer Station, coastal Dronning Maud Land, Antarctica. For the first time, inversions were studied differentiating between different synoptic conditions and different height levels. It was shown that, generally, inversions occurred on the majority (78%) of the days, with simultaneous occurrence of humidity and temperature inversions being observed on approximately two thirds of all days. Multiple inversions are common in all seasons for cyclonic and noncyclonic conditions, however, typically occur more frequently under cyclonic conditions. The seasonality of inversion occurrence and features, that is, inversion strength, depth and vertical gradients, was analysed statistically. Different formation mechanisms depending on inversion levels and prevailing weather situations are related to typical annual courses of certain inversion features. Winter maxima were found for the features that are mostly connected to the temperature close to the surface, which is mainly a result of the negative energy balance, thus influencing surface‐based inversions. At the second level, both temperature and humidity inversions are often caused by advection of comparably warm and moist air masses related to the passage of cyclones and their frontal systems. Hence, maxima in several inversion features are found in spring and fall, when cyclonic activity is strongest. Monthly mean profiles of humidity and temperature inversions reveal that elevated inversions are often obscured in average profiles due to large variations in inversion height and depth. [ABSTRACT FROM AUTHOR]

Here we review Antarctic snow accumulation variability, at the regional scale, over the past 1000 years. A total of 80 ice core snow accumulation records were gathered, as part of a community led project coordinated by the PAGES Antarctica 2k working group. The ice cores were assigned to seven geographical regions, separating the high accumulation coastal zones below 2000 m elevation from the dry central Antarctic Plateau. The regional composites of annual snow accumulation were evaluated against modelled surface mass balance (SMB) from RACMO2.4 and precipitation from ERA-interim reanalysis. With the exception of the Weddell Sea coast, the low-elevation composites capture the regional precipitation and SMB variability. The central Antarctic sites lack coherency and are either not representing regional precipitation or indicate the models inability to capture relevant precipitation processes in the cold, dry central plateau. The drivers of precipitation are reviewed for each region and the temporal variability and trends evaluated over the past 100, 200 and 1000 years. Our study suggests an overall increase in SMB across the grounded Antarctic ice sheet of ~ 44 GT since 1800 AD, with the largest (area-weighted) contribution from the Antarctic Peninsula (AP). Only four ice core records cover the full 1000 years and suggest a decrease in snow accumulation during this period. However, our study emphasizes the importance of low elevation coastal zones (especially AP and DML), which have been underrepresented in previous investigations of temporal snow accumulation. [ABSTRACT FROM AUTHOR]

To derive paleotemperatures from ice cores, the relationship between stable isotope ratios of precipitation and the condensation temperature at the deposition site is used. However, as only a few records of Antarctic condensation temperature are available, the temperature at the top of the inversion layer has been often used as a surrogate for condensation temperature. A 25-year data set of pressure, temperature, humidity, wind-speed and –direction obtained from 7664 radiosoundings performed at the German Antarctic research station "Neumayer" were used for a detailed study of temperature and humidity inversions during the time period 1993-2017. In particular, inversion strength (depth and lapse rate), frequency and seasonality and the relationship to wind-speed and -direction were investigated. 3-hourly SYNOP data (past and current weather conditions) were employed to distinguish between inversions during clear-weather conditions, which are caused by radiation processes, and advection-type inversions during the passage of cyclones. For the latter, the association with moisture transport was studied, too. It could be shown that humidity and temperature inversions are not necessarily directly related, but could occur at different times and different altitudes. Also multiple inversions were found for both temperature and humidity. These results can be further used to improve the paleoclimatological interpretation of ice cores and to contribute to the progress of numerical atmospheric modeling (e.g. precipitable water estimates) in coastal Antarctic regions. [ABSTRACT FROM AUTHOR]

During the Antarctic Circumnavigation Expedition (ACE) (Dec. 2016 - March 2017), as the name implies, a ship's cruise around entire Antarctica, precipitation was measured continuously on board "Akademik Tryoshnikov" using micro radar, a snow particle counter, and two Wenglor particle counters. Even though the data are restricted by the fact that they stem from a moving ship, they offer a unique opportunity to evaluate data from the Antarctic Mesoscale Prediction System (AMPS) for an area where no routine precipitation measurements are available. Whereas the snow particle counter only considers solid precipitation, the Wenglor particle counters and the micro radar can be used for both snow and rain measurements. Additionally, during each snowfall snowflake imprints were collected using formvar-coated slides. Particle size and geometry were analysed and used to support the determination of precipitation rates from radar and particle counter data. In the presented study, the different observational data are compared to AMPS model output, both for the whole time period of the expedition and for several high-precipitation events. AMPS basically employs (Polar) WRF and has a resolution of eight km in Domain 2 that covers the continent and the southern parts of the Southern Ocean, where the larger part of the cruise took place, and 24 km in Domain 1, which extends as far north as the tips of South America, South Africa, and Southern Australia. The synoptic situation of the precipitation events and the corresponding moisture transport are analysed. In some cases, frontal passages could be studied in detail, while in other cases the ship moved with the frontal system, so that high precipitation amounts were observed for an extended time period. [ABSTRACT FROM AUTHOR]