Seasonal snow in Antarctica Data Report

The project ’Seasonal Snow in Antarctica’ was set up to measure the physical properties of Antarctic snow cover in 1999-2001. The present document is the project data report. An introduction is given of the project, descriptions of the experiments are made, and the data obtained by the scientists in the different working groups during the two expeditions to Antarctica are described

Evolution of snow cover and dynamics of atmospheric deposits in the snow in the Antarctica. Data report

Field programme on the surface layer of the ice sheet in the Dronning Maud Land, Antarctica has been performed in 2009-2011. The objectives were to examine the annual accumulation and sublimation history, snow melting, chemistry of snow impurities, and life history of supraglacial and epiglacial lakes in blue ice regions. Fieldwork was done during FINNARP 2009 and 2010 expeditions. The sites were at the Finnish research station Aboa (73 02.5'S, 013 24.4'W), a snow line from Rampen at the edge of the ice shelf pass Aboa to the station Svea, and blue ice at Basen and neighboring nunataks. Snow measurements were made using classical snow pit method, ice and snow sampling, and with automatic observation stations (surface radiation balance, penetration of sunlight into snow and ice, and temperature within the surface layer of snow and ice). Life history, physics, and ecological state of lakes were mapped. This document is the data report including a brief project introduction, descriptions of the experiments, and the data obtained

Physics and geochemistry of lakes in Vestfjella, Dronning Maud Land

Shallow Antarctic surface lakes belong to the most extreme aquatic environments on the Earth. In Vestfjella, proglacial surface lakes and ponds are characterized by a 2-5 month long period with liquid water and depths <2 m. We give a detailed description of nine seasonal lakes and ponds situating at three nunataqs (Basen, Plogen and Fossilryggen) in western Dronning Maud Land. Their physical and geochemical properties are provided based on observations in four summers. Three main 'lake categories' were found: 1) supraglacial lakes, 2) epiglacial ponds and 3) nunataq ponds. Category 3 lakes can be divided into two subgroups with regards to whether the meltwater source is glacial or just seasonal snow patches. Supraglacial lakes are ultra-oligotrophic (electrical conductivity <10 mu S cm(-1), pH <7), while in epiglacial ponds the concentrations of dissolved and suspended matter and trophic status vary over a wide range (electrical conductivity 20-110 mu S cm(-1), pH 6-9). In nunataq ponds, the maxima were an electrical conductivity of 1042 mu S cm(-1)and a pH of 10.1, and water temperature may have wide diurnal and day-to-day fluctuations (maximum 9.3 degrees C) because snowfall, snow drift and sublimation influence the net solar irradiance.Peer reviewe

Measurements by Controlled Meteorological Balloons in Coastal Areas of Antarctica

An experiment applying controlled meteorological (CMET) balloons near the coast of Dronning Maud Land, Antarctica, in January 2013 is described. Two balloons were airborne for 60 and 106 hours with trajectory lengths of 885.8 km and 2367.4 km, respectively. The balloons carried out multiple controlled soundings on the atmospheric pressure, temperature and humidity up to 3.3 km. Wind speed and direction were derived from the balloon drift. Observations were compared with radiosonde sounding profiles from the Halley Research Station, and applied in evaluating simulations carried out with the weather research and forecasting (WRF) mesoscale atmospheric model. The most interesting feature detected by the CMET balloons was a mesoscale anticyclone over the Weddell Sea and the coastal zone, which was reproduced by the WRF model with reduced intensity. The modelled wind speed was up to 10 m s-1 slower and the relative humidity was 20-40% higher than the observed values. However, over the study period the WRF results generally agreed with the observations. The results suggest that CMET balloons could be an interesting supplement to Antarctic atmospheric observations, particularly in the free troposphere

Fine-scale model simulation of gravity waves generated by Basen nunatak in Antarctica

Peer reviewe

Displacement of the South Pole from 2006 to 2021: Role of sea ice and Antarctic surface temperature

The effect of global warming on the southern polar regions necessitates careful monitoring of glacier deformations and their movements, as well as an understanding of atmospheric physics. For this purpose, the yearly movements of UNAVCO stations-South Pole Station (AMU2) (winter-summer) and other stations in the South Pole region have been observed in this paper for about a fifteen-year period (2006–2021). In addition, the area differences of the Antarctic continent due to seasonal changes (winter-summer) between 1980 and 2021 were investigated in this study. Moreover, the height values of the stations on the Antarctic continent were observed seasonally. The subglacial lakes in the Antarctic continent cause the differences in the height values as a result of the seasonal changes. A decrease in sea ice of 0.91 million km2 for the winter season and 0.55 million km2 for the summer season during a 41-year period has been determined for four sectors of the Antarctic continent. The temperature changes on the Antarctic continent in the summer and winter seasons (2005–2022) were also evaluated in this paper. Air temperature increases was apparent especially in the Antarctic Peninsula, East Antarctic and West Antarctic coasts. The Weddell Sea and the Amundsen Sea regions have had the most sea ice loss, each with 1.24 million km2. On the other hand, it can be observed that the East Antarctic sector has expanded by 0.32 million km2

Altimetry, gravimetry, GPS and viscoelastic modeling data for the joint inversion for glacial isostatic adjustment in Antarctica (ESA STSE Project REGINA)

The poorly known correction for the ongoing deformation of the solid Earth caused by glacial isostatic adjustment (GIA) is a major uncertainty in determining the mass balance of the Antarctic ice sheet from measurements of satellite gravimetry and to a lesser extent satellite altimetry. In the past decade, much progress has been made in consistently modeling ice sheet and solid Earth interactions; however, forward-modeling solutions of GIA in Antarctica remain uncertain due to the sparsity of constraints on the ice sheet evolution, as well as the Earth's rheological properties. An alternative approach towards estimating GIA is the joint inversion of multiple satellite data – namely, satellite gravimetry, satellite altimetry and GPS, which reflect, with different sensitivities, trends in recent glacial changes and GIA. Crucial to the success of this approach is the accuracy of the space-geodetic data sets. Here, we present reprocessed rates of surface-ice elevation change (Envisat/Ice, Cloud,and land Elevation Satellite, ICESat; 2003–2009), gravity field change (Gravity Recovery and Climate Experiment, GRACE; 2003–2009) and bedrock uplift (GPS; 1995–2013). The data analysis is complemented by the forward modeling of viscoelastic response functions to disc load forcing, allowing us to relate GIA-induced surface displacements with gravity changes for different rheological parameters of the solid Earth. The data and modeling results presented here are available in the PANGAEA database (https://doi.org/10.1594/PANGAEA.875745). The data sets are the input streams for the joint inversion estimate of present-day ice-mass change and GIA, focusing on Antarctica. However, the methods, code and data provided in this paper can be used to solve other problems, such as volume balances of the Antarctic ice sheet, or can be applied to other geographical regions in the case of the viscoelastic response functions. This paper presents the first of two contributions summarizing the work carried out within a European Space Agency funded study: Regional glacial isostatic adjustment and CryoSat elevation rate corrections in Antarctica (REGINA)

annual elevation change, a digital elevation model, and surface flow velocity

The polar ice sheets are unique paleoclimatic archives and play an important role in recent and future climate. The melting of the big freshwater reservoirs will not only increase the global sea level, but will also influence the ocean currents. Therefore, it will be of particular interest to improve the currently available numeric climate models to achieve more accurate statements about climatic change and its consequences. In this work, the evaluation and the different applications of GPS and altimetry data will be described in respect to enhance models. The antarctic area of investigation, Dronning Maud Land (DML), is of particular interest for German polar research, because both the overwintering station Neumayer and the summer station Kohnen are located within it. In the surroundings of these two stations, highly accurate kinematic GPS measurement were made, which will be the basis for the digital elevation model presented here. Because these data are spatially limited, they are supplemened with remotely sensed data. For this purpose, two airborne altimetry data sets and spaceborne laser altimetry data of the Ice, Cloud, and land Elevation Satellite (ICESat) are used...thesi

Surface influence on the marine and coastal Antarctic atmosphere

The Antarctic region plays an important role in the global climate system, and it contributes to the future of global climate through changes in regional factors, such as sea ice, atmospheric circulation patterns and moisture distribution. The aim of this thesis is to improve the understanding of the influence of the Earth surface on the marine and coastal Antarctic atmosphere. The thesis outlines the characteristics of typical phenomena of the Antarctic environment both near the surface and higher in the atmosphere, and describes the challenges related to numerical modelling in the region. The work is based on combined use of several observational data sets and regional numerical modelling. Marine atmosphere and its reprensentation in regional modelling was studied based on observational data collected on two research projects called 'Short Timescale Motion of Pancake Ice', and 'Ice Station Polarstern'. The coastal atmosphere was studied based on data from the Movable Atmospheric Radar for Antarctica from Queen Maud Land and the Integrated Global Radiosonde Archive from 11 coastal stations. Model simulations were made using two regional-scale atmospheric models: the Fifth-Generation Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model (MM5) and the Weather Research and Forecasting (WRF) model. The boundary layer over the marine Antarctic was found to be strongly governed by the presence or absence of sea ice. The major challenges related to the modelling of the atmosphere over Antarctic sea ice were associated with clouds, boundary layer processes and sea ice and snow description. The model sensitivity to different physical parameterisation schemes was most profound in the lowest parts of the atmosphere. The results confirm that numerical simulations reproduce relatively accurately the basic meteorological surface variables, such as temperature, humidity, air pressure, wind speed and wind direction, over ice-covered ocean, but the turbulent and radiative fluxes that affect those variables were not that well depicted. To minimise the modelling errors, the sea ice conditions should be updated frequently with advanced description of ice and snow processes. The modelling benefits also from advanced cloud schemes with prediction of the vertical distribution of cloud water and ice content. The vertical structure of the atmosphere over the coastal Antarctic was found to be featured by internal gravity waves and temperature and humidity inversions. Gravity waves generated by a small mountain peak emerging above the ice sheet were found to reach the lower stratosphere. This implies that even small mountains can generate strong gravity waves, and it is possible to simulate them when applying high horizontal resolution in the model. Humidity inversions were found to be, nearly all the time, present on multiple levels in the coastal Antarctic atmosphere. The presented statistics for humidity inversions can be used as a baseline for further studies addressing moisture changes in the Antarctic atmosphere.Antarktiksella on tärkeä rooli maapallon ilmastosysteemissä. Se vaikuttaa merkittävästi maapallon ilmaston tulevaisuuteen paikallisten tekijöiden, kuten merijään, ilmakehän virtausrakenteiden ja kosteusjaukauman muutosten kautta. Tämän väitöskirjatyön tavoitteena on lisätä ymmärrystä maapallon pinnan vaikutuksesta ilmakehään Antarktiksen meri- ja rannikkoalueilla. Väitöskirja selvittää alueelle tyypillisten ilmiöiden ominaisuuksia pinnan lähellä sekä ylempänä ilmakehässä, ja määrittää alueen numeeriseen mallinnukseen liittyviä haasteita. Työ perustuu useiden havaintoaineistojen hyödyntämiseen ja alueelliseen numeeriseen mallinnukseen. Merialueen ilmakehää ja sen kuvausta alueellisessa mallinnuksessa tutkittiin kahden tutkimusprojektin keräämän havaintoaineiston avulla. Rannikkoalueiden ilmakehän tutkimus perustui tutkahavaintoihin Kuningatar Maudin Maalta ja radioluotauksiin 11 rannikkoasemalta. Mallisimulaatiot tehtiin käyttäen kahta alueellista ilmakehämallia. Ilmakehän rajakerrosta Antarktiksen merialueella määrittää ensisijaisesti se, onko alueella merijäätä vai ei. Suurimmat haasteet merijään yläpuolisen ilman mallittamiseen liittyivät pilviin, rajakerrosprosesseihin ja merijään ja lumen kuvaukseen. Mallin herkkyys eri fysikaalisille parametrisointimenetelmille oli selkein ilmakehän alimmissa osissa. Tulokset osoittavat, että numeerinen mallinnus voi merijään peittämällä merellä kuvata suhteellisen tarkasti meteorologisia perussuureita kuten lämpötilaa, kosteutta, ilmanpainetta, tuulen nopeutta ja tuulen suuntaa, mutta turbulenttiset ja säteilyvuot, jotka noihin suureisiin vaikuttavat, ovat huonommin mallinnettuja. Mallinnusvirheiden pienentämiseksi merijää tulisi syöttää mallisysteemiin riittävän usein sisällyttäen mukaan jään ja lumen prosessit yksityiskohtaisesti kuvattuina. Lisäksi mallinnusta parantavat edistyneet pilvien parametrisointimenetelmät, joissa on mukana pilviveden ja jään pystyjakauman ennustaminen. Ilmakehän pystyrakenteelle Etelämantereen rannikkoalueilla on tyypillistä sisäiset gravitaatioaallot ja lämpötila- ja kosteusinversiot. Pienen jäätikön yläpuolelle nousevan vuorenhuipun kehittämien gravitaatioaaltojen osoitettiin ulottuvan stratosfäärin alaosiin. Tämä viittaa siihen, että myös suhteellisen pienet vuoret voivat synnyttää voimakkaita gravitaatioaaltoja. Mallinnuksella osoitettiin, että aallot on mahdollista simuloida käyttäen tarkkaa horisontaalista resoluutiota. Kosteusinversioiden havaittiin olevan lähes jatkuvasti läsnä useissa eri kerroksissa Etelämantereen rannikkoalueen ilmakehässä. Esitettyjä kosteusinversioiden ilmastotilastoja voidaan käyttää pohjana Antarktiksen ilmakehän kosteuden muutosten jatkotutkimuksille