How does the local wind field control the aerosol distribution in coastal Dronning Maud Land?

Atmospheric circulation patterns and chemical concentrations in firn cores are highly related to each other. Atmospheric winds transport aerosols like sea salt and mineral dust over the globe and redistribute them. Because of this, it is possible to reconstruct atmospheric circulation bringing aerosol to Antarctica by analyzing chemical impurities in firn and ice. With these analyses, the gap caused by sparse atmospheric measurements can be filled and this knowledge can then be used to improve the understanding of local and global circulation patterns.Due to a very high accumulation rate (~600 kg/m²*a), coastal Dronning Maud Land (CDML) is a perfect site to conduct these studies.Here, the upper 6m of two firn cores drilled on Halvfaryggen and Sörasen (covering the time interval from 2002- 2007) were analyzed on ionic concentrations. This data was then contrasted to measurements from the air chemistry laboratories at Neumayer (NM) and Kohnenstation (KS), and synoptic measurements from automatic weather stations (distributed in CDML and at NM).The analyses show very different results: Sea salt ions (e.g. Na+) are higher correlated to ions measured in aerosol samples at the air chemistry laboratory at KS than to the one located at NM. In contrast, ions representing mineral dust (e.g. nss-Ca2+) only have a weak correlation over the whole area and time period. Accordingly, the deposition of aerosol is highly dependent on its origin and the topography in coastal Antarctica suggesting different transport pathways for sea level and higher altitude sites

Iodine monoxide in the Antarctic snowpack

Recent ground-based and space borne observations suggest the presence of significant amounts of iodine monoxide in the boundary layer of Antarctica, which are expected to have an impact on the ozone budget and might contribute to the formation of new airborne particles. So far, the source of these iodine radicals has been unknown. This paper presents long-term measurements of iodine monoxide at the German Antarctic research station Neumayer, which indicate that high IO concentrations in the order of 50 ppb are present in the snow interstitial air. The measurements have been performed using multi-axis differential optical absorption spectroscopy (MAX-DOAS). Using a coupled atmosphere snowpack radiative transfer model, the comparison of the signals observed from scattered skylight and from light reflected by the snowpack yields several ppb of iodine monoxide in the upper layers of the sunlit snowpack throughout the year. Snow pit samples from Neumayer Station contain up to 700 ng/l of total iodine, representing a sufficient reservoir for these extraordinarily high IO concentrations

Entering new areas in known fields: recombinant fusion protein linking recombinant factor VIIa with recombinant albumin (rVIIa-FP) – advancing the journey

ABSTRACTThe novel fusion protein linking recombinant factor VIIa with recombinant albumin (rVIIa-FP) is designed to extend the half-life of recombinant factor VIIa (rFVIIa) and improve the care of hemophilia A or B patients with inhibitors. Preclinical studies in various animal models have demonstrated markedly improved pharmacokinetic and pharmacodynamic properties, as well as prolonged retention in the joint tissues, of rVIIa-FP compared with a commercially available rFVIIa (NovoSeven®). A phase I study in healthy volunteers – the first study in the PROLONG-7FP program – confirmed that rVIIa-FP has a good tolerability profile in doses of up to 1,000μg/kg and has demonstrated enhanced pharmacodynamic activity relative to rFVIIa. The half-life of rVIIa-FP at the highest dose investigated in the study was 8.5hours, which represents a 3- to 4-fold half-life extension compared with rFVIIa. Encouraging results from preclinical and phase I studies have led to the initiation of clinical studies of rVIIa-FP in patients with congenital hemophilia A or B and inhibitors, and in patients with confirmed factor VII deficiency. The results from these studies are awaited with interest by clinicians and patients alike

Interval scheduling and colorful independent sets

Numerous applications in scheduling, such as resource allocation or steel manufacturing, can be modeled using the NP-hard Independent Set problem (given an undirected graph and an integer k, find a set of at least k pairwise non-adjacent vertices). Here, one encounters special graph classes like 2-union graphs (edge-wise unions of two interval graphs) and strip graphs (edge-wise unions of an interval graph and a cluster graph), on which Independent Set remains NP-hard but admits constant-ratio approximations in polynomial time. We study the parameterized complexity of Independent Set on 2-union graphs and on subclasses like strip graphs. Our investigations significantly benefit from a new structural "compactness" parameter of interval graphs and novel problem formulations using vertex-colored interval graphs. Our main contributions are: 1. We show a complexity dichotomy: restricted to graph classes closed under induced subgraphs and disjoint unions, Independent Set is polynomial-time solvable if both input interval graphs are cluster graphs, and is NP-hard otherwise. 2. We chart the possibilities and limits of effective polynomial-time preprocessing (also known as kernelization). 3. We extend Halld\'orsson and Karlsson (2006)'s fixed-parameter algorithm for Independent Set on strip graphs parameterized by the structural parameter "maximum number of live jobs" to show that the problem (also known as Job Interval Selection) is fixed-parameter tractable with respect to the parameter k and generalize their algorithm from strip graphs to 2-union graphs. Preliminary experiments with random data indicate that Job Interval Selection with up to fifteen jobs and 5*10^5 intervals can be solved optimally in less than five minutes.Comment: This revision does not contain Theorem 7 of the first revision, whose proof contained an erro

Continuous 25-yr aerosol records at coastal Antarctica: Part 2: Variability of the radionuclides 7Be, 10Be 210Pb

We investigated the variability of210Pb,7Be10Be in coastal Antarctic aerosol samples based on continuous, monthly annually resolved time series obtained from Neumayer Station over the period 1983 to 2008. Clear seasonal cycles peaking in the local summe

Year-round records of bulk and size-segregated aerosol composition in central Antarctica (Concordia site) Part 1: Fractionation of sea-salt particles

Abstract. Multiple year-round records of bulk and size-segregated composition of aerosol were obtained at the inland site of Concordia located at Dome C in East Antarctica. In parallel, sampling of acidic gases on denuder tubes was carried out to quantify the concentrations of HCl and HNO3 present in the gas phase. These time-series are used to examine aerosol present over central Antarctica in terms of chloride depletion relative to sodium with respect to freshly emitted sea-salt aerosol as well as depletion of sulfate relative to sodium with respect to the composition of seawater. A depletion of chloride relative to sodium is observed over most of the year, reaching a maximum of ~ 20 ng m−3 in spring when there are still large sea-salt amounts and acidic components start to recover. The role of acidic sulfur aerosol and nitric acid in replacing chloride from sea-salt particles is here discussed. HCl is found to be around twice more abundant than the amount of chloride lost by sea-salt aerosol, suggesting that either HCl is more efficiently transported to Concordia than sea-salt aerosol or reemission from the snow pack over the Antarctic plateau represents an additional significant HCl source. The size-segregated composition of aerosol collected in winter (from 2006 to 2011) indicates a mean sulfate to sodium ratio of sea-salt aerosol present over central Antarctica of 0.16 ± 0.05, suggesting that, on average, the sea-ice and open ocean emissions equally contribute to sea-salt aerosol load of the inland Antarctic atmosphere. The temporal variability of the sulfate depletion relative to sodium was examined at the light of air mass backward trajectories, showing an overall decreasing trend of the ratio (i.e. a stronger sulfate depletion relative to sodium) when air masses arriving at Dome C had travelled a longer time over sea-ice than over open-ocean. The findings are shown to be useful to discuss sea-salt ice records extracted at deep drilling sites located inland Antarctica. </jats:p

One year of aerosol refractive index measurement from a coastal Antarctic site

Climate change model evaluations need a better understanding of the atmo- spheric aerosols' optical properties and with this of the refractive index (RI) of atmospheric aerosols as well. Due to the remoteness of Antarctica only a very few data on the refractive index exists from there. In this paper we calculate the real refractive index of atmospheric aerosols from number size distribution measurements at a coastal Antarctic measurement site. In our calculations we used the overlapping size range (120-340 nm) of a scanning mobility sizer (SMPS), which sizes the particles by their electrical mobility, and a laser aerosol spectrometer (LAS), which sizes the particles by their optical scattering signal. Based on almost a complete year of measurement and 2439 measurement points, the average effective refractive index (RIeff) turned out to be 1.44. This is in a good agreement with the RI value of 1.47 which we derived from the chemical composition filter measurements. At our measurement site the aerosol has a very characteristic seasonal pattern in both number concentration and chemical composition. Despite this, we could not identify any significant sea- sonal variability in the effective refractive index, the monthly averages remain within the range of 1.40-1.50. Two austral winter months June and September has a slightly higher average values (1.50 and 1.47). We could not identify any in uence of the occurring wind direction on the retrieved RIeff either. For the few examples of north winds coming from the Neumayer station (occurs very rarely, this is the reason why the measurement site was built to the south), we don't see different values than for the other wind directions. During an artificial, high contamination episode, when diesel engines were operated right next to the measurement site, we had an hour of constant conditions such that one RI fit was possible. This fit resulted in an unusual high RI of 1.59, which is most probably due to the high black carbon content of the diesel engine emission. Therefore, we also assume that even during northerly wind directions we did not have significant in uence from the Neumayer station. During a shorter period between 2017 December and 2018 January we used the time averaged LAS and SMPS number size distributions to get some in- formation on the size dependency of the refractive index. The RI was fit in 5 different particle size ranges, and we have found a slight decrease of the re- fractive index with the particle size from 1.47 in the 116-168 nm to 1.37 in the 346-478 nm range

Radiocarbon in global tropospheric carbon dioxide

Since the 1950s, observations of radiocarbon (14C) in tropospheric carbon dioxide (CO2) have been conducted in both hemispheres, documenting the so-called nuclear "bomb spike" and its transfer into the oceans and the terrestrial biosphere, the two compartments permanently exchanging carbon with the atmosphere. Results from the Heidelberg global network of 14C-CO2 observations are revisited here with respect to the insights and quantitative constraints they provided on these carbon exchange fluxes. The recent development of global and hemispheric trends of 14C-CO2 are further discussed in regard to their suitability to continue providing constraints for 14C-free fossil CO2 emission changes on the global and regional scale