Inverse Methods: a Powerful Tool for Evaluating Aerosol Data, Exemplified on Cases With Relevance for the Atmosphere and the Aerosol Climate Effect

For a complete description of a given aerosol, more than one parameter is necessary, e.g. parameters concerning size distribution, chemical composition, and particle morphology. On the other hand, most instruments measuring aerosol properties are sensitive mostly to one parameter, but cross-sensitive to others. These cross-sensitivities are often eliminated by assumptions during data evaluation, inducing systematic uncertainties in the results. The use of assumptions can be reduced by combining the information of several instruments on the same aerosol and using inverse methods for interpretation of the data. The presentation focuses on two application examples of these methods. The first example concerns a size distribution inversion algorithm that combines data from several instruments into one size distribution. The second example deals with an algorithm that retrieves the aerosol asymmetry parameter (with respect to particle scattering) from measurements of the aerosol absorption and spectral scattering and hemispheric backscattering coefficients, thereby providing a set of parameters that completely describes an aerosol with respect to its direct climate effect

Dating of the Udin Boršt conglomerate terrace and implication for tectonic uplift in the northern part of the Ljubljana Basin (Slovenia)

EN:The northwestern part of the Ljubljana Basin is filled mostly with fluvioglacial sediments deposited by rivers coming from Alpine mountain groups. The Tržiška Bistrica River, flowing from the Karavanke Mountains, has deposited a large alluvial fan consisting predominantly of carbonate pebbles with subordinate amounts of siliciclastic pebbles. The oldest infill, cemented into a conglomerate terrace named Udin Boršt, overlies an erosional surface on Oligocene mudstone. The thickness of the conglomerate terrace is up to 50 m. The conglomerate terrace is well karstified; the surface is dissected by numerous dolines and covered with a thick soil sequence. There are several caves. The most important are spring caves formed on the contact with the underlying impermeable basement. Samples of quartz pebbles were taken from the walls and ceiling in the 815 m long spring Arneševa Luknja Cave for cosmogenic nuclides burial age dating. The calculated burial age yielded an age of 1.86 ± 0.19 Ma that gives (i) the age of the oldest known infill in the Ljubljana Basin and (ii) indicates the time of change of the sedimentary system in the Basin from erosion to deposition. The age of the Udin Boršt karst and caves is significantly younger. The age dates provide grounds for a first relatively firm estimate of the long-term tectonic uplift of the Udin Boršt terrace to be between 0.06 and 0.04 mm/yr. This tectonic uplift rate may be related to the activity of the regional Sava Fault.SLO:Severozahodni del Ljubljanske kotline pokrivajo večinoma fluvioglacialni sedimenti, ki so jih odložile reke iz alpskih gorskih skupin. Tržiška Bistrica, ki priteka iz Karavank je odložila velik vršaj. V njem prevladujejo karbonatni prodniki z manjšim deležem siliciklastičnih prodnikov. Ta najstarejša zapolnitev, sprijeta v konglomeratno teraso Udin boršt, leži na erozijskem površju oblikovanem v oligocenskih glinovcih. Debelina konglomeratne terase je do 50 m. Konglomeratna terasa je dobro zakrasela, površje pa je razčlenjeno z vrtačami in pokrito z debelo plastjo prsti. V njej je več jam, med katerimi so najpomembnejše izvirne jame, ki so se oblikovale na stiku z neprepustno podlago. V 815 m dolgi Arneševi luknji smo vzeli iz sten in stropa jame vzorec iz kremenovih prodnikov za določitev pokopne starosti prodnega zasipa s kozmičnimi nuklidi. Izračunana starost prekritja sedimentov je 1.86 ± 0.19 Ma. Ta datacija določa (i) starost najstarejše sedimentne zapolnitve v Ljubljanski kotlini in (ii) čas spremembe v sedimentacijskem sistemu kotline iz erozije v sedimentacijo. Starost kraških oblik in jam v Udin borštu je znatno mlajša. Starost sedimenta daje tudi osnovo za relativno trdno določitev tektonskega dviga terase Udin boršta na 0,06 do 0,04 mm/yr. Ta tektonski dvig je verjetno povezan z premiki ob regionalnem savskem prelomu

Chronostratigraphy of the Hochterrassen in the lower Lech valley (Northern Alpine Foreland)

Hochterrassen (High or Higher Terraces) are a prominent geomorphological feature of the Northern Alpine Foreland and have traditionally been attributed to the Rissian glaciation. However, distinct morphological sublevels observed for this feature have often raised the question of their age. This issue is exemplarily investigated here on the Langweider and Rainer Hochterrassen in the lower Lech valley using different relative and numerical dating techniques. The lowest sublevel, the Übergangsterrasse is only preserved in small patches at the western rim of the Rainer Hochterrasse and is most probably of early Würmian age. The sublevel of the Jüngere Hochterrasse is older than the Last Interglacial, as indicated by luminescence ages of overlying loess/palaeosol sequence and the development of a luvisol on top of the terrace gravel. This terrace is composed of stacked gravel units that represent at least two accumulation phases correlating with Marine Isotope Stage (MIS) 6 for the top gravel and MIS 7 to MIS 10 (or older) for the basal gravel. It is not yet clear, if the deposition of the basal gravel unit corresponds to one or more aggradation phases during the Middle Pleistocene. The highest sublevel, the Ältere Hochterrasse also shows a compositon of two stacked gravel units but so far, no numerical ages have been achieved for these units.researc

Drilling Overdeepened Alpine Valleys (ICDP-DOVE): Quantifying the age, extent, and environmental impact of Alpine glaciations

The sedimentary infill of glacially overdeepened valleys (i.e., structures eroded below the fluvial base level) is an excellent but yet underexplored archive with regard to the age, extent, and nature of past glaciations. The ICDP project DOVE (Drilling Overdeepened Alpine Valleys) Phase 1 investigates a series of drill cores from glacially overdeepened troughs at several locations along the northern front of the Alps. All sites will be investigated with regard to several aspects of environmental dynamics during the Quaternary, with focus on the glaciation, vegetation, and landscape history. Geophysical methods (e.g., seismic surveys), for example, will explore the geometry of overdeepened structures to better understand the process of overdeepening. Sedimentological analyses combined with downhole logging, analysis of biological remains, and state-of-the-art geochronological methods, will enable us to reconstruct the erosion and sedimentation history of the overdeepened troughs. This approach is expected to yield significant novel data quantifying the extent and timing of Middle and Late Pleistocene glaciations of the Alps. In a first phase, two sites were drilled in late 2021 into filled overdeepenings below the paleolobe of the Rhine Glacier, and both recovered a trough filling composed of multiphase glacial sequences. Fully cored Hole 5068_1_C reached a depth of 165m and recovered 10m molasse bedrock at the base. This hole will be used together with two flush holes (5068_1_A, 5068_1_B) for further geophysical cross-well experiments. Site 5068_2 reached a depth of 255m and bottomed out near the soft rock-bedrock contact. These two sites are complemented by three legacy drill sites that previously recovered filled overdeepenings below the more eastern Alpine Isar-Loisach, Salzach, and Traun paleoglacier lobes (5068_3, 5068_4, 5068_5). All analysis and interpretations of this DOVE Phase 1 will eventually lay the ground for an upcoming Phase 2 that will complete the pan-Alpine approach. This follow-up phase will investigate overdeepenings formerly occupied by paleoglacier lobes from the western and southern Alpine margins through drilling sites in France, Italy, and Slovenia. Available geological information and infrastructure make the Alps an ideal area to study overdeepened structures; however, the expected results of this study will not be restricted to the Alps. Such features are also known from other formerly glaciated mountain ranges, which are less studied than the Alps and more problematic with regards to drilling logistics. The results of this study will serve as textbook concepts to understand a full range of geological processes relevant to formerly glaciated areas all over our planet

Snežna jama (Slovenia): Interdisciplinary dating of cave sediments and implication for landscape evolution

AbstractCaves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps

Degenerate flag varieties: moment graphs and Schr\"oder numbers

We study geometric and combinatorial properties of the degenerate flag varieties of type A. These varieties are acted upon by the automorphism group of a certain representation of a type A quiver, containing a maximal torus T. Using the group action, we describe the moment graphs, encoding the zero- and one-dimensional T-orbits. We also study the smooth and singular loci of the degenerate flag varieties. We show that the Euler characteristic of the smooth locus is equal to the large Schr\"oder number and the Poincar\'e polynomial is given by a natural statistics counting the number of diagonal steps in a Schr\"oder path. As an application we obtain a new combinatorial description of the large and small Schr\"oder numbers and their q-analogues.Comment: 25 page

On Aethalometer measurement uncertainties and an instrument correction factor for the Arctic

Several types of filter-based instruments are used to estimate aerosol light absorption coefficients. Two significant results are presented based on Aethalometer measurements at six Arctic stations from 2012 to 2014. First, an alternative method of post-processing the Aethalometer data is presented, which reduces measurement noise and lowers the detection limit of the instrument more effectively than box-car averaging. The biggest benefit of this approach can be achieved if instrument drift is minimised. Moreover, by using an attenuation threshold criterion for data post-processing, the relative uncertainty from the electronic noise of the instrument is kept constant. This approach results in a time series with a variable collection time (Delta t) but with a constant relative uncertainty with regard to electronic noise in the instrument. An additional advantage of this method is that the detection limit of the instrument will be lowered at small aerosol concentrations at the expense of temporal resolution, whereas there is little to no loss in temporal resolution at high aerosol concentrations (>2.1-6.7Mm(-1) as measured by the Aethalometers). At high aerosol concentrations, minimising the detection limit of the instrument is less critical. Additionally, utilising co-located filter-based absorption photometers, a correction factor is presented for the Arctic that can be used in Aethalometer corrections available in literature. The correction factor of 3.45 was calculated for low-elevation Arctic stations. This correction factor harmonises Aethalometer attenuation coefficients with light absorption coefficients as measured by the co-located light absorption photometers. Using one correction factor for Arctic Aethalometers has the advantage that measurements between stations become more inter-comparable.Peer reviewe