ALBERT

Beschreibung: Surface snow samples were collected daily, at several sites representing distinct environments: sea ice, inland close to sea level, and a hilltop ~600 m above sea level (asl), from a Canadian high Arctic location at Eureka, Nunavut (80°N, 86°W) from the end of February to the end of March in 2018 and 2019. Snow samples were under ionic and salinity analysis. The aim of this study is to explore the role of snowpack in polar spring boundary layer chemistry, especially as a direct source of reactive bromine (BrO〈sub〉X〈/sub〉=BrO+Br) and nitrogen (NO〈sub〉X〈/sub〉=NO+NO〈sub〉2〈/sub〉). We find that surface snow bromide at sea level is significantly enriched, indicating a net sink of atmospheric bromine. Both surface snow bromide and nitrate at sea level have an increasing trend over the measurement time period. Using these trends, we derive an integrated net deposition flux of bromide of 1.01×10〈sup〉7〈/sup〉 molecules cm〈sup〉-2〈/sup〉 s〈sup〉-1〈/sup〉 and of nitrate of 2.6×10〈sup〉8〈/sup〉 molecules cm〈sup〉-2〈/sup〉 s〈sup〉-1〈/sup〉. In addition, nitrate and bromide in the morning samples are significantly higher than the afternoon samples, indicating a strong photochemistry effect, however the bromide loss rate is smaller than the nitrate loss rate by more than an order of magnitude. Also, surface snow nitrate and bromide at inland sites are significantly correlated (R=0.48-0.76), with a [NO〈sub〉3〈/sub〉〈sup〉-〈/sup〉]/[Br〈sup〉-〈/sup〉] ratio of 4-7 indicating a possible acceleration effect of reactive bromine in atmospheric NO〈sub〉X〈/sub〉-to-nitrate conversion. This is the first time we see such an effect from snow chemistry data obtained with a sampling frequency as short as one day.

Beschreibung: The low Antarctic sea ice extent (SIE) following its dramatic decline in late 2016 has persisted over a multiyear period. However, it remains unclear to what extent this low SIE can be attributed to changing ocean conditions. Here, we investigate the causes of this period of low Antarctic SIE using a coupled climate model partially constrained by observations. We find that the subsurface Southern Ocean (SO) played a smaller role than the atmosphere in the extreme SIE low in 2016, but was critical for the persistence of negative anomalies over 2016-2021. Prior to 2016, the subsurface SO warmed in response to enhanced westerly winds. Decadal hindcasts show that subsurface warming has persisted and gradually destabilized the ocean from below, reducing SIE over several years. The simultaneous variations in the atmosphere and ocean after 2016 have further amplified the decline in Antarctic SIE.

Beschreibung: A constellation of radiation belts survey (CORBES) program is proposed by the Sub-Group on Radiation Belt (SGRB) of TGCSS, COSPAR, which is in pursuit of the goal of SGRB, focusing on the implementation of a Small/CubeSats constellation mission for radiation belt exploration. Basing on a general review of the status quo of research on the Earth's radiation belts dynamics and the unresolved scientific issues, the scientific object and observation requirements of CORBES are proposed. The CORBES program is expected to have a constellation of 10-plus small/ CubeSats to take an ultra-fast survey of the Earth’s radiation belt. The general science goal for CORBES is to investigate two groups of physical processes related to the radiation belts: wave-particle interactions and radial transport. This program is an international multilateral cooperation mission, an open and sharing data policy will be implemented. The data set of observations will be shared within the contributors of the constellation and the broad research community at large, then would be of great use for comprehensively understanding the dynamics of magnetospheric energetic populations and developing more standard models of the Earth’s radiation belts. Furthermore, from the application perspective, the ultra-fast survey of the radiation belt could serve as an important facility for monitoring space weather of the Earth as well.

Beschreibung: This dataset contains predictions of Earth orientation parameters (EOP) submitted during the Second Earth Orientation Parameters Prediction Comparison Campaign (2nd EOP PCC). The 2nd EOP PCC has been carried out by Centrum Badań Kosmicznych Polskiej Akademii Nauk CBK PAN in Warsaw in cooperation with the GFZ German Research Centre for Geosciences in Potsdam (Germany) and under the auspices of the International Earth Rotation and Reference Systems Service (IERS) within the IERS Working Group on the 2nd EOP PCC. The purpose of the campaign was to re-assess the current capabilities of EOP forecasting and to find most reliable prediction approaches. The operational part of the campaign lasted between September 1, 2021 and December 28, 2022. Throughout the duration of the 2nd EOP PCC, registered campaign participants submitted forecasts for all EOP parameters, including dX, dY, dPsi, dEps (components of celestial pole offsets), polar motion, differences between universal time and coordinated universal time, and its time-derivative length-of-day change. These submissions were made to the EOP PCC Office every Wednesday before the 20:00 UTC deadline. The predictions were then evaluated once the geodetic final EOP observations from the forecasted period became available. Each participant could register more than one method, and each registered method was assigned an individual ID, which was used, e.g., for file naming. The dataset contains text files with predicted parameters as submitted by campaign participants and MATLAB file which is a database with all correct predictions from each participant loaded into a structure.

Beschreibung: Apatite is a ubiquitous phase in granite plutons and in most adjacent country rocks, thus contamination of a granite magma with wall-rock material results in two genetic types of apatite in the magma: cognate and foreign. These two textural and chemical varieties of apatite undergo textural and compositional changes to reach physical and chemical equilibrium (perfect assimilation) in the melt. Our experiments replicate the conditions in such contaminated granites. The starting materials consist of a peraluminous synthetic SiO2-Al2O3-Na2O-K2O (SANK 1.3) granite gel with A/NK of 1.3, synthetic F-apatite, synthetic Cl-apatite, and natural Durango apatite. Initial experiments in cold-seal hydrothermal pressure vessels at magmatically realistic temperatures of 750 °C and pressures of 200 MPa produced negligible reactions, even after run times of 2000 h. Instead, we used an argon-pressurized internally heated pressure vessel with a rapid-quench setup at temperatures of 1200 °C, pressure of 200 MPa, and run durations of 192 h. An advantage of this high temperature is that it exceeds the liquidus for quartz and feldspar; therefore, apatite is the only solid phase in the run products. The starting composition of each run was 90 wt% SANK 1.3 granite gel and 10 wt% crushed apatite (consisting of one, two, or three varieties), with and without 4 wt% added H2O. Run products were examined by SEM for texture and by EMPA and LA-ICP-MS for composition. The starting synthetic granite composition contains no Ca, F, Cl, or REEs thus, in every run, apatite was initially undersaturated in the melt. In all experiments, most large apatite grains consisted of anhedral shards with rounded corners, most small apatite grains were round, and a small proportion of apatite grains developed one or more crystal faces. In experiments with two or three apatite compositions, the run-product apatite grains had compositions intermediate between those of the starting-material grains, and they were homogeneous with respect to Cl, and probably F, but not with respect to REEs. The processes to reach textural equilibrium consist of dissolution until the melt is saturated in apatite, followed by Ostwald ripening to eliminate small grains and to develop crystal faces on larger ones. The processes to reach chemical equilibrium consist of dissolution of apatite, diffusion of cations (Ca, P, REE) and anions (F, Cl, OH) through the silicate melt, and solid-state diffusion in the undissolved apatite grains. The halogens approached chemical equilibrium in all experiments, but in the experiments containing Durango apatite, the REEs have not. Models involving radial diffusion into spherical apatite grains at the temperatures of the experiments show complete re-equilibration of the halogens, but changes in the REE concentrations affecting only the outer few micrometers. We conclude that the rate of chemical equilibrium for the halogens is greater than the rate of physical equilibrium for texture, which in turn is greater the rate of chemical equilibrium for REEs. We illustrate these processes with a natural example of contaminated granite from the South Mountain Batholith in Nova Scotia. Given that all granites are contaminated rocks, we propose that future petrogenetic studies focus on developing techniques for a minerals-based quantitative estimation of contamination (QEC).

Beschreibung: Global climate warming is accelerating permafrost degradation. The large amounts of soil organic matter in permafrost-affected soils are prone to increased microbial decomposition in a warming climate. Along with permafrost degradation, changes to the soil microbiome play a crucial role in enhancing our understanding and in predicting the feedback of permafrost carbon. In this article, we review the current state of knowledge of carbon-cycling microbial ecology in permafrost regions. Microbiomes in degrading permafrost exhibit variations across spatial and temporal scales. Among the short-term, rapid degradation scenarios, thermokarst lakes have distinct biogeochemical conditions promoting emission of greenhouse gases. Additionally, extreme climatic events can trigger drastic changes in microbial consortia and activity. Notably, environmental conditions appear to exert a dominant influence on microbial assembly in permafrost ecosystems. Furthermore, as the global climate is closely connected to various permafrost regions, it will be crucial to extend our understanding beyond local scales, for example by conducting comparative and integrative studies between Arctic permafrost and alpine permafrost on the Qinghai–Tibet Plateau at global and continental scales. These comparative studies will enhance our understanding of microbial functioning in degrading permafrost ecosystems and help inform effective strategies for managing and mitigating the impacts of climate change on permafrost regions.