Abstract This work investigated the annual variations in dry snow (DSRZ) and wet snow radar zones (WSRZ) in the north of the Antarctic Peninsula between 2015-2023. A specific code for snow zone detection on Sentinel-1 images was created on Google Earth Engine by combining the CryoSat-2 digital elevation model and air temperature data from ERA5. Regions with backscatter coefficients (σ⁰) values exceeding -6.5 dB were considered the extent of surface melt occurrence, and the dry snow line was considered to coincide with the -11 °C isotherm of the average annual air temperature. The annual variation in WSRZ exhibited moderate correlations with annual average air temperature, total precipitation, and the sum of annual degree-days. However, statistical tests indicated low determination coefficients and no significant trend values in DSRZ behavior with atmospheric variables. The results of reducing DSRZ area for 2019/2020 and 2020/2021 compared to 2018/2018 indicated the upward in dry zone line in this AP region. The methodology demonstrated its efficacy for both quantitative and qualitative analyses of data obtained in digital processing environments, allowing for the large-scale spatial and temporal variations monitoring and for the understanding changes in glacier mass loss. (DSRZ (WSRZ 20152023. 20152023 2015 2023. 2023 2015-2023 Sentinel1 Sentinel 1 Sentinel- CryoSat2 CryoSat 2 CryoSat- ERA5 ERA σ⁰ σ (σ⁰ 6.5 65 6 5 -6. occurrence 11 -1 C precipitation degreedays. degreedays degree days. days degree-days However variables 20192020 2019 2020 2019/202 20202021 2021 2020/202 20182018 2018 2018/201 region environments largescale large scale loss 2015202 201 202 2015-202 (σ 6. -6 - 2019202 2019/20 2020202 2020/20 2018201 2018/20 201520 20 2015-20 201920 2019/2 202020 2020/2 201820 2018/2 20152 2015-2 20192 2019/ 20202 2020/ 20182 2018/ 2015-

Abstract This study evaluated feasibility statistically and analyzed, during the freezing period, the relationship between brightness temperature (Tb) data of the 37V polarisation and the GR3719 (Gradient Ratio 37V and 19V) obtained by Special Sensor Microwave/Imager from F11 and F13 satellites with sea ice thickness (SIT) data obtained in the Weddell Sea through Antarctic Sea Ice Processes and Climate program. The multiple linear regression (MLR) was applied at 1,520 points, with 70% of these points being randomly separated to generate the MLR and 30% to carry out the validation. To perform the temporal mapping, the MLR was applied only to pixels with sea ice concentration (SIC) ≥ 90%, obtained through the fraction image calculated from the spectral linear mixing model (SLMM) using the Tb in the channels and polarizations 19H, 19V and 37V. The results of the SLMM validation process for estimating the SIC were σ = 10.5%, RMSE = 11.0%, and bias = -2.8%, and the SIT based on the MLR, the results were R² = 0.57, RMSE = 0.268 m, and bias = 0.103 m. In the SIT mapping, we highlight the trend of thickness reduction on the east coast of the Antarctic Peninsula during the period 1992–2009. analyzed (Tb V GR GR371 Gradient MicrowaveImager Microwave Imager F F1 (SIT program (MLR 1520 1 520 1,52 70 30 mapping (SIC 90 90% (SLMM 19H H 105 10 5 10.5% 110 11 0 11.0% 2.8%, 28 2 8 -2.8% R 057 57 0.57 0268 268 0.26 m 0103 103 0.10 19922009 1992 2009 1992–2009 GR37 152 52 1,5 7 3 9 10.5 11.0 2.8% -2.8 05 0.5 026 26 0.2 010 0.1 1992200 199 200 1992–200 GR3 15 1, 10. 11. 2.8 -2. 0. 02 01 199220 19 20 1992–20 2. -2 19922 1992–2 - 1992–

Abstract This work consists of the sedimentological, mineralogical, and geochemical characterization of eight marine sediment cores collected in the Central Bransfield Basin, along a transect between the South Shetland Islands to the Antarctic Peninsula and its correlation to the sedimentary and oceanographic processes of the area. A chemical characterization based on X-ray fluorescence dispersive spectrometry was implemented to obtain geochemical data of the marine sediment while the minerals were identified by X-ray diffraction. The study allowed to classify the cores into three groups according to their sediment source and chemical and mineralogical characteristics. The joint assessment of the geochemical and mineralogical signature of the sediment has confirmed that the elemental ratios Ti/Ca and Fe/Ca can be applied as proxies in the reconstitution of the terrigenous contribution to the Central Bransfield Basin if we consider the sedimentary contribution of the volcanic edifices present in the region. The Fe/K ratio associated with the Chemical Index of Alteration reinforced an increase in the degree of weathering near South Shetland Island, which is also pointed out by other authors in studies on climate change mainly in the subantarctic islands. The trend of temperature increase implies the importance of monitoring the region. sedimentological area Xray X ray diffraction characteristics TiCa Ti Ca FeCa Fe region FeK K Island islands

Abstract This work aimed to characterize the variation in the thermal regime of the active layer in a permafrost area on Fildes Peninsula, Antarctica, and relate this variability with meteorological data between 2014 and 2016. The monitoring site was installed to continuously monitor the temperature and moisture of the active layer, radiation flow on the surface, and air temperature. We used data collected to generate the indexes freezing degree-days, thawing degree-days, frost number, n-factor, apparent thermal diffusivity, and active layer thickness. The temperature of the active layer is not homogeneous, varying with depth and position in the transect, with the greatest variations in soil with better drainage and lower moisture content. Among the evaluated factors, air and soil surface temperature are the ones that most influence the thermal gradient of the active layer. We identified that near the surface there is a greater influence of albedo and cloudiness and at -35 cm depth there is a greater influence of net radiation and soil moisture. The average depth of the active layer in 2014 was -44.3 cm and in 2015 -47.7 cm and the frost number index indicates that there was a predominance of continuous permafrost in the transect during the monitoring. Peninsula Antarctica 201 2016 degreedays, degreedays degree days, days degree-days nfactor, nfactor n factor, factor n-factor diffusivity thickness homogeneous content factors 35 -3 44.3 443 44 3 -44. 47.7 477 47 7 -47. 20 - 44. 4 -44 47. -47 2 -4

Abstract Several studies have utilized passive microwave imagery for monitoring snowmelt in Antarctica. However, due to the low spatial resolution of these images (25 km), the quantification of snowmelt is not precise. To enhance the accuracy of these estimations, this study proposed a subpixel analysis approach based on a Spectral Linear Mixing Model. This approach was applied to images obtained from channels 18/19 GHz and 37 GHz, both horizontally and vertically polarized, acquired from the Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave Imager (SSM/I), and Special Sensor Microwave Imager/Sounder (SSM/IS) instruments, spanning the period 1978-2018. The spatiotemporal analysis of the estimated snowmelt fraction images indicated that the most persistent and intensive melt was observed on the Antarctic Peninsula, particularly on the Larsen, Wilkins, George VI, and Wordie ice shelves. The melting period in the Antarctic Peninsula began in late October, with a peak in early January, and ended in late March. Other regions with persistent and intensive snowmelt were Mary Bird Land and Wilkes Land, followed by Dronning Maud Land, Amery Ice Shelf, Filchner-Ronne Ice Shelf, and Ross Ice Shelf. These snowmelt data are valuable for modeling the impacts of snowmelt on glacial systems, local coastal environments, and sea-level rise. Antarctica However 25 (2 km, km , km) precise estimations Model 1819 18 19 18/1 3 polarized SMMR, SMMR (SMMR) SSM/I, SSMI SSM/I SSM I (SSM/I) ImagerSounder Sounder SSM/IS SSMIS IS (SSM/IS instruments 19782018. 19782018 1978 2018. 2018 1978-2018 Larsen Wilkins VI shelves October January March Shelf FilchnerRonne Filchner Ronne systems environments sealevel sea level rise 2 ( 181 1 18/ (SMMR (SSM/I 1978201 197 201 1978-201 197820 20 1978-20 19782 1978-2 1978-

Abstract This study aims to investigate the glacier shrinkage and recent proglacial environment in King George Bay, Antarctica, since 1988 in response to climate change. Remote sensing data (SPOT, Sentinel, Landsat and Planet Scope images) were applied to glacial landforms and ice-marginal fluctuations mapping. Annual mean near-surface air temperature reanalysis solutions from ERA-Interim were analyzed. Moraines and glaciofluvial landforms were identified. The Ana Northern Glacier has the highest retreat value (3.64 km) (and area loss of 31%) in response to higher depth in frontal ice-margin and reveal ocean-glacier linkages. The Ana South Glacier changed from a tidewater glacier to land-terminating after 1995, and had an outline minimum elevation variation of 89 meters, a shrinkage of 0.63 km, and a new proglacial subaerial sector. The Ana South Glacier foreland had recessional moraines (probably formed between 1995 and 2022), lagoons, and lakes. There are many flutings in low-relief environments. The 1980-1989, 1990-1999, 2000-2009, 2010-2019 anomaly plots concerning to the 1980-2019 average for atmospheric temperature, are shown to be a driver of the local glacial trends. Bay Antarctica 198 change SPOT, SPOT (SPOT Sentinel images icemarginal ice marginal mapping nearsurface near surface ERAInterim ERA Interim analyzed identified 3.64 364 3 64 (3.6 km 31% 31 icemargin margin oceanglacier ocean linkages landterminating land terminating 8 meters 063 0 63 0.6 sector probably 199 2022, 2022 , 2022) lagoons lakes lowrelief low relief environments 19801989, 19801989 1980 1989, 1989 1980-1989 19901999, 19901999 1990 1999, 1999 1990-1999 20002009, 20002009 2000 2009, 2009 2000-2009 20102019 2010 2019 2010-201 19802019 1980-201 trends 19 3.6 36 6 (3. 06 0. 202 1980198 1980-198 1990199 1990-199 2000200 200 2000-200 2010201 201 2010-20 1980201 1980-20 1 3. (3 20 198019 1980-19 199019 1990-19 200020 2000-20 201020 2010-2 198020 1980-2 ( 2 19801 1980-1 19901 1990-1 20002 2000-2 20102 2010- 19802 1980- 1990- 2000-

Abstract A 22.48 m long ice core (BR-IC-4) was collected in the West Antarctic Ice Sheet (at 83°58’59.4” S, 80°07’01.4” W, 1,295 m above the sea level) during the Austral summer of 2004–2005, as a contribution to the International Trans-Antarctic Expedition program. The isotopic composition (δD and δ18O) of 599 samples, corresponding to the upper 12.98 m of the ice core, was determined by gas source mass spectrometry and cavity ring-down spectroscopy. Relative dating was based on the isotopic ratios and major ions (MS-, Na+, nssSO4 2-) and trace elements (Na, S, Sr) concentrations. The record covers approximately 13 years – from 1990 to 2003. The mean accumulation rate of 0.48 ± 0.09 m water equivalent per year (m eq H2O a1) is relatively high for the geographical area and possibly results from snowdrifting from near areas, as attested by ice glaze surfaces in other sites in the region. The stable isotope δD content varies between -367.90‰ and 256.30‰ (mean -314.42 ± 19.01‰); and δ18O ranges from -44.96‰ to 35.08‰ (mean -39.95 ± 2.05‰). Deuterium excess values (mean 3.70 ± 1.54‰) indicate episodic intense oceanic evaporation and high relative humidity in the moisture sources. 2248 22 48 22.4 BRIC4 BRIC BR IC 4 (BR-IC-4 at 83°5859.4 8358594 83°58 59.4 83 58 59 83°58’59.4 S 80°0701.4 8007014 80°07 01.4 80 07 01 80°07’01.4 W 1295 1 295 1,29 level 20042005 2004 2005 2004–2005 TransAntarctic Trans program δO δ O samples 1298 12 98 12.9 ringdown ring down spectroscopy MS, MS , (MS- Na Na+ nssSO 2 2- Na, (Na Sr concentrations 199 2003 048 0 0.4 009 09 0.0 HO H a1 areas region 367.90‰ 36790 367 90 -367.90 25630 256 30 256.30 314.42 31442 314 42 -314.4 19.01‰ 1901 19 19.01‰) 44.96‰ 4496 44 96 -44.96 3508 35 08 35.08 39.95 3995 39 95 -39.9 2.05‰. 205 2.05‰ . 05 2.05‰) 370 3 70 3.7 1.54‰ 154 54 sources 224 22. (BR-IC- 5859 83°5859. 835859 8358 83°5 594 59. 8 5 83°58’59. 0701 80°0701. 800701 8007 80°0 014 01. 80°07’01. 129 29 1,2 2004200 200 2004–200 9 12. (MS 04 0. 00 367.90 3679 36 -367.9 2563 25 256.3 314.4 3144 31 -314. 19.01 190 44.96 449 -44.9 350 35.0 39.9 399 -39. 20 2.05 37 7 3. 1.54 15 (BR-IC 585 83°5859 83585 835 83° 83°58’59 070 80°0701 80070 800 80° 80°07’01 1, 200420 2004–20 367.9 -367. 256. 314. -314 19.0 44.9 -44. 35. 39. -39 2.0 1.5 83°585 83°58’5 80°070 80°07’0 20042 2004–2 367. -367 -31 19. 44. -44 -3 2. 1. 83°58’ 80°07’ 2004– -36 -4 -

Abstract We used Sentinel-2 imagery time series to generate a vegetation map for the Northern part of the Antarctica Peninsula and offshore islands, including the South Shetlands. The vegetation cover was identified in the NDVI maximum value composite image. The NDVI values were associated with the occurrence of algae (0.15 – 0.20), lichens (0.20 – 0.50), and mosses (0.50 – 0.80). The vegetation cover distribution map was validated using the literature information. Generating a vegetation map distribution on an annual basis was not possible due to high cloud cover in the Antarctic region, especially in coastal áreas, so optical images from 2016 to 2021 were necessary to map the vegetation distribution in the entire study área. The final map analyzed in association with the weather data shows the occurrence of a microenvironment over the western islands of the Antarctic Peninsula that provided vegetation growth conditions. The Sentinel-2 images with 10m spatial resolution allow the assembly of accurate vegetation distribution maps for the Antarctica Peninsula and Islands, the Google Earth Engine cloud computing being essential to process a large amount of the satellite images necessary for processing these maps. Sentinel2 Sentinel 2 Sentinel- Shetlands image 0.15 015 0 15 (0.1 0.20, 020 0.20 , 20 0.20) (0.2 0.50, 050 0.50 50 0.50) (0.5 0.80. 080 0.80 . 80 0.80) information region áreas 201 202 área conditions m Islands 0.1 01 1 (0. 02 0.2 05 0.5 5 08 0.8 8 0. (0 (

Abstract This article compares isotopic, ionic and climatic data from two firn cores from the West Antarctic Ice Sheet (WAIS). The IC-02 (88°01’21.3”S , 82°04’21.7”W) and the IC-05 (82°30’30.8”S , 79°28’02.7”W) closer to the coast. The IC-02 had 488 samples analyzed covering 14.58 meters depth while the IC-05 had 602 samples analyzed covering 19.73 meters depth. The time interval for both ice cores is 25 years ranging from 1978 to 2003. Sodium, sulfate and chloride were analyzed via ion chromatography using three DionexTM ionic chromatographers at the laboratories of Centro Polar e Climático (CPC) and at the Climate Change Institute. Stable isotope data was determined using cavity ring-down spectroscopy in a Picarro® spectrometer at the CPC. Annual accumulation was greater at IC-05 with an average of 0.35 m.eq.w.a-1 compared to 0.25 m.eq.w.a-1 at the IC-02. Stable isotope data was approximately 1.3 times more negative at the IC-02 which also presented higher d values. Na+ and Cl- were in higher concentrations at the IC-05 however Cl/Na was greater in the IC-02. The Cl excess was found to be derived from fractionation of sea salt aerosols and not related to volcanism. This work presents new insights regarding the chemical differences between ice cores. isotopic WAIS. WAIS . (WAIS) IC02 IC 02 IC-0 88°0121.3S 8801213S S 88°01 21.3 88 01 21 3 82°0421.7W 8204217W W 82°04 21.7 82 04 7 82°04’21.7”W IC05 05 82°3030.8S 8230308S 82°30 30.8 30 8 79°2802.7W 7928027W 79°28 02.7 79 28 79°28’02.7”W coast 48 1458 14 58 14.5 60 1973 19 73 19.7 2 197 2003 Sodium CPC (CPC Institute ringdown ring down Picarro 035 0 35 0.3 m.eq.w.a1 meqwa1 meqwa m.eq.w.a 1 m eq w m.eq.w.a- 025 0.2 IC02. 02. 13 1. values Na ClNa volcanism (WAIS IC0 IC- 0121 3S 8801 88°0 213 21. 0421 7W 8204 82°0 217 3030 8S 8230 82°3 308 30. 2802 7928 79°2 027 4 145 5 14. 6 19. 200 03 0. a1 012 880 88° 042 820 82° 303 823 280 792 79° 20

Abstract This study investigates the transient snowline (TSL) altitude for summer 2020, as well as glacial area loss in King George Island Icefields since 1988 using Sentinel-1 and 2 and Landsat Thematic Mapper (TM) imagery. Trends and anomalies in atmospheric temperature, U-wind, and V-wind were examined using ERA5 solutions. Results show the wet-snow zone corresponds to values of ≤ -13dB, and 44.3% of the glacial area is located above the TSL (≥ 300 m). Glacial area for 2020 is 999.95 km², and losses in the period represent 104.9 km² (error <1%) – a retreat of 3.17 km² / year. Glaciers in Keller Peninsula and Bellingshausen Dome lost the most area (28% and 17%, respectively) and did not have a TSL in 2020; followed by Warszawa (15%), Kraków (13%), and Eastern (10%), where the TSL was verified. Percentage area loss values increased with decreases in dimensions, area above TSL, and maximum elevation. Calving glaciers with ice-flow toward deeper and steeper submarine sectors (Bransfield Strait) exhibited greater glacier variations. The trend in warming atmospheric temperature was greater in the Bransfield Strait than in the Drake Passage. TSL and retreat difference between glaciers were influenced by climatic and ocean input, as well as multiple environmental factors. (TSL 198 Sentinel1 Sentinel 1 Sentinel- TM (TM imagery Uwind, Uwind U wind, wind U-wind Vwind V ERA solutions wetsnow wet snow 13dB, 13dB dB -13dB 443 44 3 44.3 ≥ ( 30 m. m . m) 202 99995 999 95 999.9 km 1049 104 9 104. error <1% 317 17 3.1 year 28% 28 (28 17% respectively 15%, 15 15% , (15%) 13%, 13 13% (13%) 10%, 10 10% (10%) verified dimensions elevation iceflow ice flow variations Passage input factors 19 4 44. 20 9999 99 999. <1 31 3. (2 (15% (13% (10% < (15 (13 (10 (1

Abstract We have estimated a 1-D permittivity model from a 100m long variable offset GPR in the West Antarctic ice sheet. That model inherits the inaccuracies in depth from the velocity model, which should be corrected before attempting to correlate it with the density log from a close-by borehole. We performed that correction by aligning a synthetic ice density derived from a Maxwell Garnett two-phase mixture model to the ice core density measurements through dynamic time warping. The shifts to bring the permittivity estimates to their proper depths suggest a direct correlation of radar-derived data to borehole depths may suffer from noise to an unknown degree. The present methodology is within reach of a standard GPR survey, having at least one variable offset gather.

Abstract The remote sensing techniques must be used to obtain long-term information in remote areas, like the Antarctic continent, to monitor the environmental productivity and its changes. The aim of this work was to analyze the surface reflectance profile patterns for the Antarctic biological soil crusts (algae, lichens, and mosses) in an area of Nelson Island (South Shetland Islands, maritime Antarctic), calculated from Landsat and Sentinel-2 images to identify its similarities and differences due to targets, sensors and acquired date. The surface reflectance values for Antarctic biological soil crusts are similar for those observed for biological soil crusts in other Earth extreme environments, like deserts. In Landsat images, the differences among biological soil crusts surface reflectance were identified at visible and near-infrared wavelengths and for Sentinel-2 images, the differences occur at visible, red-edge and shortwave infrared wavelengths, showing the feasibility of using surface reflectance products to identify these different crusts, despite its inherent pixel spectral mixture. Long-term biophysical parameters from such crusts as retrieved from orbital data is not possible due to very low cloud-free images over the Antarctic, which prevents building a consistent surface reflectance time-series which covers all biological soil crusts growth season.

Abstract This study investigated the water isotopic content (δ18O, δD, d-excess) of the surface snow along a 995 km traverse over the West Antarctic Ice Sheet from the Möller Ice Stream – Institute Ice Stream to the upper reaches of the Pine Island Glacier drainage basin. The purpose of this study was to evaluate the climatic record preserved in the snow. We analyzed 92 surface samples (~0.15–0.20 m deep), retrieved during 2014/2015 austral summer from every ~10 km along the traverse route, using the laser spectroscopy technique. We computed the isotopic-geographical characteristics and spatial co-isotopic empirical relationships and compared the isotopic results with the tropospheric mean annual temperature and air mass trajectories. Our isotopic results were sensitive to capturing the well-known climatic asymmetry between the Amundsen-Bellingshausen Sea (ABS; which receives more influence from warmer (oceanic) air masses) and Weddell Sea (WS; more influenced by colder (continental) air masses) sectors. Further, the spatial distribution of δs and d-excess and the co-isotopic relationships reflect two preferential fractionation paths: one from the coast of the ABS sector to the WS sector, and another from the coast of the WS sector to the inland. The Pacific Ocean is confirmed as the primary source of moisture.