Study of vertical structure of aerosol optical properties with sun photometers and ceilometer during the MACRON campaign in 2007

This paper presents the measurements of a vertical structure of aerosol optical properties performed during the MACRON (Maritime Aerosol, Clouds and Radiation Observation in Norway) campaign, which took place in July and August 2007 at ALOMAR observatory on Andøya island (69.279°N, 16.009°E, elevation 380 m a.s.l.). The mean value of the aerosol optical thickness (AOT) at 500 nm during campaign was 0.12. Significant increase of the AOT above longtime mean value was observed on 7 and 8 August 2007 when the AOT exceeded 0.4 at 500 nm. Analyses of back trajectories show the aerosol transported from over Africa and Central Europe. The aerosol extinction coefficient obtained from the synergy of ceilometer and sun photometer observations reached 0.05–0.08 km^?1 (at 1064 nm) in the dust layer. The single scattering albedo at the ALOMAR observatory decreased during the dust episode to 0.93–0.94, which indicates some absorptive aerosols in the lower PBL.     

Studies of aerosols advected to coastal areas with the use of remote techniques

This paper presents the results of the studies of aerosol optical properties measured using lidars and sun photometers. We describe two case studies of the combined measurements made in two coastal zones in Crete in 2006 and in Rozewie on the Baltic Sea in 2009. The combination of lidar and sun photometer measurements provides comprehensive information on both the total aerosol optical thickness in the entire atmosphere as well as the vertical structure of aerosol optical properties. Combination of such information with air mass back-trajectories and data collected at stations located on the route of air masses provides complete picture of the aerosol variations in the study area both vertically and horizontally. We show that such combined studies are especially important in the coastal areas where depending on air mass advection directions and altitudes the influence of fine or coarse mode (in this case possibly sea-salt) particles on the vertical structure of aerosol optical properties is an important issue to consider.     

Impact of the surface temperature and vertical shear of zonal wind on the dynamics of a simple two-layer model of the atmosphere

The paper presents and analyzes, from the point of view of smooth dynamic systems theory, a two-layer baroclinic model of the troposphere in geostrophic approximation. The model describes airflow in β-channel within the tropospheric part of the main Hadley circulation cell. It enables to obtain, after application of the Galerkin method, a fairly simple low-parametric dynamic system describing the phenomena of non-linear interactions, bifurcations and blocking in the atmosphere. This enables to take into consideration such basic factors influencing the atmospheric dynamics like the heat exchange within the surface, orography, vertical variability of zonal wind and hydrostatic stability. Impact of zonal thermal variability of the surface and vertical shear of zonal wind in the troposphere on the orographic bifurcation was investigated and the oscillation character in the dynamic system after Hopf bifurcation of the second kind was analyzed. Additionally, the model dynamics was investigated in conditions including momentum forcing in the upper and lower parts of the troposphere and excluding orographic interaction, as well as in the conditions of thermal interaction between the troposphere and the surface for the vertical shear of zonal wind in both tropospheric layers. Impact of the mean zonal wind in the troposphere on the properties of model dynamics was assessed. It was proved that zonally varied surface temperature and layered mean zonal wind in the atmosphere are the parameters that have basic influence on the model dynamics. They cause numerous bifurcations and strongly influence the periods of oscillations of the model variables. They are often Hopf bifurcations of the second kind during which tropospheric states fairly distant from the ones before the bifurcations are generated. This significantly influences the model predictability.     

Assessment of long‐term Holocene soil erosion rates in Polish loess areas using sedimentary archives from closed depressions

Soil erosion is a particularly important problem in the loess areas of Central Europe. Numerous studies of past and present soil erosion based on colluvial sediments have so far been conducted. The main problem is the fact that colluvia usually do not represent the complete sedimentation record. Closed depressions (CDs) collect all colluvial sediments from their catchment, therefore, constitute sediment stores enabling the calculation of soil erosion rates. Colluvial sediments and fossil soils, infilling four CDs in the Polish loess belt, were OSL and C‐14 dated. Human settlements near the studied CDs were analyzed. Phases of soil erosion and colluviation from the Neolithic (5400–2900 bc ), from the Middle Bronze Age to the Early Iron Age (1600–0 bc ), and from the Early Middle Ages to Modern Times (500 AD until today) were documented within the CDs studied. Phases of low soil erosion rate and pedogenesis occurred from the Late Vistulian to the Early Neolithic and from the Iron Age to Early Middle Ages. This study reveals that these phases are not synchronous with the soil erosion phases in Central Europe, as the latter mainly occurred in the Bronze Age, Roman Period and Middle Ages. The obtained soil erosion rates were compared with erosion rates in different areas of Central Europe. This study indicates that in loess regions with long‐term agricultural land use, mean erosion rates (i.e. 3.7–5.9 t ha^‐1 yr^‐1) from the Middle Ages to Modern Times were ten times higher than during the entire prehistoric period (0.39–0.67 t ha^‐1 yr^‐1). The mean soil erosion rates for forested CDs was 0.24–0.74 t ha^‐1 yr^‐1. Soil erosion phases are most probably caused by human activities (i.e. land use change) but the early Holocene erosion phase (7.96 +/‐ 0.67 kyr) could have been induced by a climatic fluctuation (e.g. a 8.2 kyr Bond event). Copyright © 2018 John Wiley & Sons, Ltd.     

Magnetic mineralogy and paleomagnetism of serpentinized ultramafic rocks from the Braszowice-Brzeźnica fragment of sudetic paleozoic ophiolite

Complex paleomagnetic, rock-magnetic and mineralogical studies were performed on serpentinized utramafic rocks from Braszowice-Brze?nica massif (BB) situated at the southern extremity of the Niemcza Shear Zone, close to the Sudetic Marginal Fault. Studies of magnetic minerals revealed presence of several varieties of magnetite grains, and partly altered Cr-spinels. Paleomagnetic studies revealed stable component HS of natural remanence carried by magnetite formed probably during the initial serpentinization. The directions of HS have good grouping within each locality, but differ between localities. Studies of anisotropy of magnetic susceptibility (AMS) have shown that directions of anisotropy axes are steep instead of horizontal as is common within the Niemcza Shear Zone. Taking advantage of the directions of AMS we rotated the directions of HS and brought them to the reference direction for the Sudetes for 372 Ma. We suggest that after acquiring AMS and HS during the Upper Devonian, the BB became divided into multiple units due to tectonic activity in the region.     

Geostatistical evaluation of magnetic indicators of forest soil contamination with heavy metals

The goal of the study was the geostatistical evaluation of quantitative magnetic measures, which can be used for effective delineation of the extent of the area polluted with heavy metals. Several parameters of magnetic susceptibility, measured in the soil profile, were proposed as magnetic indicators of soil pollution and analyzed in detail. The following parameters were calculated: maximum magnetic susceptibility, magnetic susceptibility at the depth of 3 cm and 5 cm, and the area under the curve of magnetic susceptibility. Measurements were performed at two forested study areas, located in Upper Silesian Industrial Area (Poland). Analyses were performed using geostatistical methods, and the results were verified using dense chemical measurements. The results showed that the area under curve of magnetic susceptibility was the most effective magnetic indicator of soil contamination with heavy metals. It was possible to detect the entire polluted area, and only about 16% of the study area was assumed to be contaminated while being unpolluted. The results obtained with maximum magnetic susceptibility and magnetic susceptibility at the depth of 3 cm and 5 cm were less effective in comparison with the area under curve of magnetic susceptibility.     

Sublimation-driven evolution of the local radius and the moment of inertia of a long-period comet

In this paper we intend to analyze how the sublimation of ice from cometary nuclei affects changes of the moments of inertia. Our aim is to show general trends for different orientations of cometary nucleus’ rotation axis. Thus we apply numerical model of a hypothetical homogeneous and initially spherical nucleus composed of water ice and dust. As an example we present simulations for a model comet of the orbital elements and the nucleus size the same as determined for C/1995 O1 Hale-Bopp, a widely analyzed long-period comet. We calculated water production from the nucleus and changes of the shape (initially spherical) and of the moment of inertia versus time. Simulations are performed for the full range (0–90°) of inclinations I of the rotation axis. The second paramater related to the orientation of the rotation axis is the argument Φ (0–360°). The heat conductivity of the nucleus spans over the vast range, 0.04–4 W m⁻¹ K⁻1.     

Pre-Variscan basement rocks in southern Poland: Where is the southeastern margin of eastern Avalonia (Cadomia)?

Summary Pre-Variscan basement in southern Poland is poorly exposed and thus known mostly from subsurface data. The availability of the latter is reviewed for terrains located between the Sudetes and the East European Platform. In these terrains the following relationships have been documented: Cadomian granitoids capped by Variscan flysch, Palaeozoic platform strata, Palaeozic folded and partly thermally altered successions, and low-grade metamorphic rocks overlain by Middle Cambrian strata. In view of their interrelationships the location of the Avalonia-Baltica suture in southeastern Poland is uncertain.     

Thermomagnetic properties of some Late Mesozoic diabase dikes of South Spitsbergen

Summary Laboratory investigations of thermomagnetic properties of specimens from seven diabase dikes of South Spitsbergen have been performed. Studies of temperature variation of isothermal saturation remanence combined with Hopkinson effect measurements and investigations of low temperature remanence give information on the mineral composition of the magnetic phases present in the magnetic fraction of the diabases. The experiments show that the clean natural remanence of these dikes has been acquired at the time of their, consolidation in the Late Mesozoic, though three of them may have been partially remagnetized at the time of Tertiary orogeny. Since the dikes reveal several normal and reversed directions of clean natural remanence, it is concluded that they were formed at different times in the Late Mesozoic, even though some of them may have been subjected to secondary influences at a later date.