Abstract Sea ice is a critical component of the cryosphere and plays a role in the heat and moisture exchange processes between the ocean and atmosphere, thus regulating the global climate. With climate change, detailed monitoring of changes occurring in sea ice is necessary. Therefore, an analysis was conducted to evaluate the potential of using the Gray Level Co-occurrence Matrix (GLCM) texture analysis combined with the backscattering coefficient (σ°) of HH polarization in Sentinel-1A Synthetic Aperture Radar (SAR) images, interferometric imaging mode, for mapping sea ice in time series. Data processing was performed using cloud computing on the Google Earth Engine platform with routines written in JavaScript. To train the Random Forest (RF) classifier, samples of regions with open water and sea ice were obtained through visual interpretation of false-color SAR images from Sentinel-1B in the extra-wide swath imaging mode. The analysis demonstrated that training samples used in the RF classifier from a specific date can be applied to images from other dates within the freezing period, achieving accuracies ≥ 90% when using 64-bit grayscale quantization in GLCM combined with σ° data. However, when using only σ° data in the RF classifier, accuracies ≥ 93% were observed. atmosphere change necessary Therefore Cooccurrence Co occurrence (GLCM σ (σ° Sentinel1A SentinelA Sentinel 1A A (SAR mode series JavaScript (RF falsecolor false color Sentinel1B SentinelB 1B B extrawide extra wide period 90 64bit bit 64 However 93 observed (σ 9 6

Abstract The Antarctic Peninsula is undergoing rapid climate changes, impacting its surrounding marine ecosystem. At that site, sea ice plays a crucial role in this ecosystem by serving as a habitat for organisms and influencing primary productivity. Studying sea ice variability and primary productivity is essential for understanding environmental changes in Antarctica. This research focused on Joinville Island, located at the tip of the Antarctic Peninsula, where meteorological data and glaciochemical analysis were conducted on snow/firn cores for Cl-, Na+, Ca2+, Mg2+, SO4 2-, NO3 -, K+, MSA, NH4 + and F- to retrieve recent past environmental variabilities. The study revealed that Joinville Island experienced a net accumulation rate of 0.40 meters per year in water equivalent between 1993 and 2005. In snow/firn cores, Na+ correlated with both wind strength and sea ice extent (r=0.59 and r=0.66, respectively) while correlations were higher for MSA and Cl- with respect to sea ice (r=0.80 and r=0.74, respectively), considering both the Weddell and Amundsen-Bellingshausen sub-sectors. This analysis contributes to our understanding of sea ice dynamics and its influence on primary productivity in the area. site Antarctica snowfirn snow firn Cl, Cl , Na Ca2 Ca Ca2+ Mg2 Mg Mg2+ SO 2, 2 2- NO - K K+ NH F variabilities 040 0 40 0.4 199 2005 r=0.59 r059 r 59 (r=0.5 r066 66 r=0.66 respectively r=0.80 r080 80 (r=0.8 r074 74 r=0.74 respectively, AmundsenBellingshausen Amundsen Bellingshausen subsectors. subsectors sub sectors. sectors sub-sectors area 04 4 0. 19 200 r=0.5 r05 5 (r=0. r06 6 r=0.6 r=0.8 r08 8 r07 7 r=0.7 1 20 r=0. r0 (r=0 r=0 (r= r= (r

Abstract Glaciers are sensitive to environmental climatic conditions and show their variability over time. This study investigates the environmental characteristics and variation in glacial cover of the Greenwich, Livingston, Robert and Snow islands, Antarctica, between 1956 and 2023. The glacier extension mapping was based on visual interpretation of the Landsat 4, 7 and 8 optical images and normalised difference indexes combination. The REMA 8 digital elevation model was applied to the islands’ geomorphometric analysis. Results were compared to climatic series and environmental characteristics. The glacial coverage decreased by 16.9% from 1956 to 2023, equivalent to 209.95 ± 0.113 km². Snow Island, with shallow bathymetry near glacial margins and land-terminating ice-fronts, exhibited the smallest retreat rate values. The glacial coverage of Livingston Island decreased significantly (18%, equivalent to 153.2 ± 0.113 km²) from 1956-2021, representing the highest values in the study. The changes in glacial coverage of the Robert and Greenwich islands were more substantial in the 1989-2023 period than in 1956-1989. Sectors with marine-terminating glaciers, associated with high bathymetric amplitudes, exhibited more significant variations compared to other sectors, contributing to the evolution of fjord-type bays. Glacial coverage has been lost in recent decades due to regional atmospheric and oceanic warming. time Antarctica 195 2023 4 combination analysis 169 16 9 16.9 20995 209 95 209.9 0113 0 113 0.11 km² km landterminating land terminating icefronts, icefronts ice fronts, fronts ice-fronts 18%, 18 (18% 1532 153 2 153. 19562021, 19562021 2021, 2021 1956-2021 19892023 1989 1989-202 19561989. 19561989 1989. 1956-1989 marineterminating marine glaciers amplitudes sectors fjordtype fjord type bays warming 19 202 1 16. 2099 20 209. 011 11 0.1 18% (18 15 1956202 1956-202 1989202 198 1989-20 1956198 1956-198 01 0. (1 195620 1956-20 198920 1989-2 195619 1956-19 ( 19562 1956-2 19892 1989- 19561 1956-1 1956-

Abstract This study investigated the chemical content of a shallow snow core (4.95 m) named TT 6, collected during a Brazilian traverse of the West Antarctic Ice Sheet in the 2014/2015 Austral summer. Stable isotope ratios (δD and δ18O) and ionic content, determined at the Centro Polar e Climático of the Federal University of Rio Grande do Sul (CPC/UFRGS), were used to date the core and reconstruct the climatic conditions at the site. The core represents approximately 11 years ± 6 months of precipitation, i.e., a mean net snow accumulation rate of 0.19 ± 0.02 m a-1 in water equivalent. Using the non-sea-salt sulfate values, we identified the 2011 Puyhue-Cordón (Chile) volcanic eruption signal, providing a reference horizon for dating. Anions represent 53.73% of the ionic content. We identified that 96.86% of calcium and 84.50% of sulfate are non-sea origin, while the acidic contribution is 25.62% H+. We observed high peaks in marine aerosols containing Na+, Cl-, and Mg2+ during winter, and results from the ERA5 global model (NOAA) indicated that El Niño events could influence Antarctic temperatures, facilitating the transport of marine aerosols to the continent. 4.95 495 4 95 (4.9 20142015 2014 2015 2014/201 summer δD δ18O δO δ O CPC/UFRGS, CPCUFRGS CPC/UFRGS , CPC UFRGS (CPC/UFRGS) site 1 precipitation ie i i.e. 019 0 19 0.1 002 02 0.0 a1 a- equivalent nonseasalt non sea salt values 201 PuyhueCordón Puyhue Cordón Chile (Chile signal dating 5373 53 73 53.73 9686 96 86 96.86 8450 84 50 84.50 nonsea origin 2562 25 62 25.62 H H+ Na Na+ Cl, Cl Cl- Mg2 Mg winter ERA NOAA (NOAA temperatures continent 4.9 49 9 (4. 2014201 2014/20 (CPC/UFRGS i.e 01 0. 00 20 537 5 7 53.7 968 8 96.8 845 84.5 256 2 25.6 4. (4 201420 2014/2 53. 96. 84. 25. ( 20142 2014/

Abstract Regional sea level rise varies from the global average and is influenced by climate variability. We studied sea level anomalies in southern Brazil from 1993 to 2022, finding increasing trend from 1993 to 2022. We used oceanic and atmospheric dynamics to understand the rapid sea level rise. Positive trends in the Southern Annular Mode and the South Atlantic Ocean subtropical gyre intensified wind stress curl and Ekman transport. If global warming continues and the Southern Annular Mode remains in a positive trend, sea level rise in southern Brazil is likely to persist and increase risks for the population in this low-lying coastal area. variability 199 2022 transport lowlying low lying area 19 202 1 20 2

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 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.

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.

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.

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.

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.

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.

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.

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.