ABSTRACT. A Syste© me probatoire pour l'observation de la terre (SPOT) mosaic of King George Island, the largest (1250 km 2 ) of the South Shetland Islands,West Antarctica, shows its major morphological features. Three main ice domes and 70 glacier drainage basins, covering 92.7% of the King George Island area, strongly controlled by the subglacial morphology and drained by relatively fast-moving tidewater outlet glaciers, were delineated. A general retreat of ice fronts through four decades, more intensely on the eastern side of the island (to the Bransfield Strait), resulted in the loss of about 7% of the glacial cover area. Superficial snow facies were derived from SPOT multispectral imagery and, together with field observations, allowed the transient-snowline elevation to be obtained. The latter is estimated to have risen from about 200^250 m in the mid-1950s to 300^350 m by 1988. Spot radio-echo sounding surveys give an overview of the bedrock morphology.

The Brazilian Cerrado is a global biodiversity hotspot with notoriously high rates of native vegetation suppression and wildfires over the past three decades. As a result, climate change can already be detected at both local and regional scales. In this study, we used three different approaches based on independent datasets to investigate possible changes in the daytime and nighttime temperature and air humidity between the peak of the dry season and the beginning of the rainy season in the Brazilian Cerrado. Additionally, we evaluated the tendency of dew point depression, considering it as a proxy to assess impacts on biodiversity. Monthly increases of 2.2−4.0℃ in the maximum temperatures and 2.4−2.8℃ in the minimum temperatures between 1961 and 2019 were recorded, supported by all analyzed datasets which included direct observations, remote sensing, and modeling data. The warming raised the vapor pressure deficit, and although we recorded an upward trend in absolute humidity, relative humidity has reduced by ~15%. If these tendencies are maintained, gradual air warming will make nightly cooling insufficient to reach the dew point in the early hours of the night. Therefore, it will progressively reduce both the amount and duration of nocturnal dewfall, which is the main source of water for numerous plants and animal species of the Brazilian Cerrado during the dry season. Through several examples, we hypothesize that these climate changes can have a high impact on biodiversity and potentially cause ecosystems to collapse. We emphasize that the effects of temperature and humidity on Cerrado ecosystems cannot be neglected and should be further explored from a land use perspective.

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Os Complexos Convectivos de Mesoescala (CCM) são aglomerados organizados de nuvens convectivas, que atingem com freqüência a Região Sul do Brasil e produzem uma grande variedade de desastres. Este trabalho identificou os CCMs ocorridos entre outubro e dezembro de 2003 no Rio Grande do Sul (RS) e avaliou os desastres associados aos eventos. A identificação dos CCMs foi feita através do aplicativo ForTraCC - DSA/INPE. O levantamento das ocorrências de desastres foi realizado a partir do cruzamento dos dias de eventos de CCM com as informações da Defesa Civil do RS (DCRS) e do Jornal Correio do Povo. Foram identificados 22 eventos de CCM no período, responsáveis por 42 episódios de vendaval, 21 de enxurrada, 14 de enchente, cinco de granizo associado à vendaval, três de granizo, dois de alagamento, dois de inundação e um deslizamento, totalizando 90 ocorrências. Houve registro de seis mortes no RS e cinco em Santo Tomé na Argentina, fronteira com o Estado. Mais de 16.500 pessoas foram atingidas e cerca de 60% dos municípios que comunicaram desastres à DCRS decretaram situação de emergência. Em média, a cada quatro eventos de CCM, três produziram algum tipo de desastre no RS.

An ice core, 92.26 m in length, was collected near the ice divide of the West Antarctica ice sheet during the 2008/2009 austral summer. This paper described the fieldwork at the Mount Johns site (79º55'S; 94º23'W) and presented the first results of the upper 45.00 m record covering approximately 125 years (1883 -2008), dated by annual layer counting and volcanic reference horizons. Trace element concentrations in 2,137 samples were determined using inductively coupled plasma mass spectrometry. The concentrations obtained for Al, Ba, Ca, Fe, K, Mg, Mn, Na, Sr and Ti are controlled by climate variations, the transport distance, and the natural sources of these aerosols. Natural dust contributions, mainly derived from the arid areas of Patagonia and Australia, are important sources for aluminum, barium, iron, manganese and titanium. Marine aerosols from sea ice and transported by air masses are important sources of sodium and magnesium. Calcium, potassium and strontium showed considerable inputs of both continental dust and marine aerosols. KEYWORDS:Trace elements; Ice core; West Antarctica ice sheet; ICP-SFMS. RESUMO: Um testemunho de neve de 92,26 m foi coletado em um dos divisores da bacia de drenagem glacial do manto de gelo da Antártica Ocidental no verão austral de 2008/2009. Este artigo descreveu os trabalhos de campo no sítio Mount Johns (79º55'S; 94º23'W) e apresentou os resultados das análises dos 45,00 m do registro superiores do testemunho e que representam cerca de 125 anos (1883 -2008) de precipitação de neve, datados por meio da contagem anual das camadas e dos horizontes vulcânicos de referência. Os elementos-traço estudados neste trabalho foram determinados usando espectrometria

Abstract. The Mount Johns (MJ) ice core (79°55′ S; 94°23′ W) was drilled near the Pine Island Glacier ice divide on the West Antarctic Ice Sheet during the 2008–2009 austral summer, to a depth of 92.26 m. The upper 45 m of the record covers approximately 125 years (1883–2008), showing marked seasonal variability. Trace element concentrations in 2137 samples were determined using inductively coupled plasma mass spectrometry. In this study, we reconstruct mineral dust and sea salt aerosol transport and investigate the influence of climate variables on the elemental concentrations at the MJ site. The ice core record reflects changes in emissions as well as atmospheric circulation and transport processes. Our trajectory analysis shows distinct seasonality, with strong westerly transport in the winter months and secondary northeasterly transport in the summer. During summer months, the trajectories present slow-moving (short) transport and are more locally influenced than in other seasons. Finally, our reanalysis correlations with trace element suggest that marine-derived trace element concentrations are strongly influenced by sea ice concentration and sea surface temperature anomalies. The results show that seasonal elemental concentration maxima in sea salt elements correlate well with the sea ice concentration winter maxima in the west Amundsen and Ross seas. Lastly, we observed an increased concentration of marine aerosols when sea surface temperature decreased.

ResumoA Geleira Ecology, localizada no litoral oeste da baía do Almirantado, Ilha Rei George, Ilhas Shetland do Sul, retrocedeu 400 m, aproximadamente, desde os anos 70, gerando uma complexa mescla de ambientes subglacial, glaciofluvial, morâinico e glaciomarinho. Observações na área deglaciada dos modernos processos deposicionais e a distribuição de depósitos e geoformas são apresentadas no presente trabalho. A área deglaciada exibe depósitos remobilizados e não consolidados, clastos estriados e materiais redepositados em uma variedade de geoformas glaciais e proglaciais, as quais são suscetíveis ao trabalho paraglacial por meio de processos não glaciais que ocorrem às margens e junto à frente da geleira. Foram identificadas quatro zonas geomórficas: cordões morainicos, zona subglacial, zona glaciofluvial e zona de influência marinha. Depósitos subglaciais formados junto à zona frontal da geleira Ecology podem ser transformados tantos por processos terrestres como por processos glaciomarinhos. Palavras-chaves:Retração glacial; Geoformas proglaciais; Geleira Ecology; Ilha Rei George; Antártica. AbstractEcology Glacier, located at the western shore of Admiralty Bay, King George Island, South Shetlands Island has retreated approximately 400 m since 1970s, generating a complex of intermixed subglacial, glaciofluvial, morainic and glacimarine environments. Observations on the deglaciation area, of the modern depositional processes and the distribution of deposits and landform are reported in the present work. The deglacial area shows remobilized and unconsolidated deposits, striated boulder pavements and redepositional entrained material in a variety of glacial and proglacial landforms, which are susceptible to paraglacial reworking by non-glacial processes occurring around and within the margin of the glacier. Four geomorphic zones were identified: morainic ridges, subglacial, glaciofluvial and marine influenced zones. Subglacial deposits formed near the frontal zone of Ecology Glacier may be transformed by both terrestrial and glaciomarine processes.

A new topographic database for King George Island, one of the most visited areas in Antarctica, is presented. Data from differential GPS surveys, gained during the summers 1997/98 and 1999/2000, were combined with up to date coastlines from a SPOT satellite image mosaic, and topographic information from maps as well as from the Antarctic Digital Database. A digital terrain model (DTM) was generated using ARC/INFO GIS. From contour lines derived from the DTM and the satellite image mosaic a satellite image map was assembled. Extensive information on data accuracy, the database as well as on the criteria applied to select place names is given in the multilingual map. A lack of accurate topographic information in the eastern part of the island was identified. It was concluded that additional topographic surveying or radar interferometry should be conducted to improve the data quality in this area. In three case studies, the potential applications of the improved topographic database are demonstrated. The first two examples comprise the verification of glacier velocities and the study of glacier retreat from the various input data-sets as well as the use of the DTM for climatological modelling. The last case study focuses on the use of the new digital database as a basic GIS (Geographic Information System) layer for environmental monitoring and management on King George Island.