Spatial modelling of summer climate indices based on local climate zones: expected changes in the future climate of Brno,Czech Republic

Climatic Change - With global climate change ongoing, there is growing concern about future living conditions in urban areas. This contribution presents the modelled spatial distribution of two...     

Magnetic fabric variations in Mesozoic black shales, Northern Siberia, Russia: Possible paleomagnetic implications

A 28-m-long section situated on the coast of the Arctic Ocean, Russia (74°N, 113°E) was extensively sampled primarily for the purpose of magnetostratigraphic investigations across the Jurassic/Cretaceous boundary. The section consists predominantly of marine black shales with abundant siderite concretions and several distinct siderite cemented layers. Low-field magnetic susceptibility (k) ranges from 8 × 10^− 5 to 2 × 10^− 3 SI and is predominantly controlled by the paramagnetic minerals, i.e. iron-bearing chlorites, micas, and siderite. The siderite-bearing samples possess the highest magnetic susceptibility, usually one order of magnitude higher than the neighboring rock. The intensity of the natural remanent magnetization (M₀) varies between 1 × 10^− 5 and 6 × 10^− 3 A/m. Several samples possessing extremely high values of M₀ were found. There is no apparent correlation between the high k and high M₀ values; on the contrary, the samples with relatively high M₀ values possess average magnetic susceptibility and vice versa. According to the low-field anisotropy of magnetic susceptibility (AMS), three different groups of samples can be distinguished. In the siderite-bearing samples (i), an inverse magnetic fabric is observed, i.e., the maximum and minimum principal susceptibility directions are interchanged and the magnetic fabric has a distinctly prolate shape. Triaxial-fabric samples (ii), showing an intermediate magnetic fabric, are always characterized by high M₀ values. It seems probable that the magnetic fabric is controlled by the preferred orientation of paramagnetic phyllosilicates, e.g., chlorite and mica, and by some ferromagnetic mineral with anomalous orientation in relation to the bedding plane. Oblate-fabric samples (iii) are characterized by a bedding-controlled magnetic fabric, and by moderate magnetic susceptibility and M₀ values. The magnetic fabric is controlled by the preferred orientation of phyllosilicate minerals and, to a minor extent, by a ferrimagnetic fraction, most probably detrital magnetite. Considering the magnetic fabric together with paleomagnetic component analyses, the siderite-bearing, and the high-NRM samples (about 15% of samples) were excluded from further magnetostratigraphic research.     

Seasonal Temperature and Precipitation Fluctuations in Selected Parts of Europe During the Sixteenth Century

The article in hand presents a comparative analysis of unweighted thermic and hygric index series of different European regions (northern Switzerland, Germany, the Czech Republic, northern Italy, ancient Hungary, Poland and Spain). Besides methodological aspects about the formation of indices, especially the progress as well as the question of similarity development of these series in the 16th century are discussed and shown on the balance sheet. It becomes evident that with respect to the temperature on the level of unweighted indices the European regions of Germany, the Czech Republic and Switzerland are very similar during all seasons. In winter and summer these correlations are especially evident, during the transitional seasons they are smaller. Larger differences exist between the central European core region and the adjacent areas of research. In principle, the hygric differences are larger than the thermic ones.In the course of the sixteenth century marked cooling phases occurred during all seasons with increasing accentuation. These phases were typical for the climate of the Little Ice Age. In addition to this long-term analysis, some outstanding years of extreme weather like those of 1540, 1573 and 1587 are presented, in the course of which questions of climatic impact are included. Finally, recent instrumental data was used to conduct an analysis that compared the similarities between the respective regions and the similarities between the empirical data and indices. On the one hand, this confirmed the spatial pattern, on the other hand the usability of the indices.     

Soil temperature in an open site and below two plantation forest canopies in a tropical highland area,southern Ethiopia

This paper examines soil temperature (Ts) in two different plantation forests relative to an adjacent open land area in a tropical highland environment. To achieve the objectives, Ts in a Juniperus procera (JP) plantation, a Grevillea robusta (GR) plantation, and in the adjacent open land (OL) area were measured. One-way ANOVA and Pearson’s correlation were used for the data analysis. The result indicated that the mean daily Ts in the OL area at 10-cm depth of the soil was greater than the mean daily Ts recorded in the JP and GR plantations by 5 °C and 6 °C, respectively. The OL area Ts recorded at different soil depths (10 cm and 20 cm) was significantly different (p < 0.05). Rainfall (RF) and air temperature (Ta) of the study area have a direct relationship with the Ts in the plantation forests. The RF and Ta do not have a significant relationship with the Ts in the OL area at 10-cm soil depth. Overall, the study indicated that the Ts in the open land area was highly fluctuating monotonically, while it is relatively constant in the plantation forests.     

Diurnal dynamics of streamflow in an upland forested micro‐watershed during short precipitation‐free periods is altered by tree sap flow

Diurnal variations in streamflow are becoming acknowledged as a way of analysing how changing climatic conditions and land use affects watersheds but also as a way to understand watersheds as a whole. Yet not many studies from uplands below 900 mm mean annual precipitation zone are available from European countries. During the 2012 growing season, a sampling campaign took place in an upland forested micro‐watershed, Czech Republic (65 ha). Tree sap flow, rainfall and temperature were measured continuously, while streamflow at the discharge point and soil moisture were estimated from short‐term measurements. Short precipitation‐free periods lasting several days were identified for evaluation of trends in diurnal dynamics of both sap flow and streamflow. The results demonstrated that during these periods, the main factor altering streamflow was almost exclusively tree sap flow. A decrease in streamflow was observed during the day and an increase at night. The decline in sap flow after sunset was accompanied by a continuous increase in streamflow throughout the night up to its initial maximum in the morning. The amplitude in diurnal variations reached 18%. The observed time lag between the diurnal variations of sap flow and streamflow was approximately 2 h. Relatively low changes in diurnal dynamics of streamflow pointed out a strong regulatory role of the forest in buffering water discharge from the catchment. Copyright © 2015 John Wiley & Sons, Ltd.     

Geometrical aspects of differential GPS positioning

Differential GPS positioning is considered from the purely geometric point of view. The tetrahedron formed by two ground stations and two satellite locations is the basic geometrical building block for differential satellite positioning. Relationships between the various vectors involved in this tetrahedron are described. These relationships are used to develop linear mathematical models which relate the vector baseline between the two ground stations to various kinds of differential GPS observations. Geometrically, all proposed observation types can be considered as either differential range observations or differential range difference observations. In the absence of instrumental and refraction effects, it is found that differential range observations are geometrically superior to differential range difference observations. Some implications of these geometrical considerations to practical differential GPS positioning are discussed.     

Energy of selected events of 1985/86 west-bohemian earthquake swarm

Summary The energy of seismic waves (i.e. seismic energy) of 60 selected events of the 1985/86 West-Bohemian swarm is determined by time integrating records. The energies lie in the interval 30 × 10³ – 0·4 × 10⁹ J for events of magnitude 0·74 – 2·59. Problems of the resultant reliability and estimation of errors are discussed. A study of the relations of seismic energy versus magnitude, of the scalar seismic moment and the source radius has shown that the processed data fit theoretical formulas in general, but individual events display scatters as large as an order of magnitude. Rather small values of the stress-drop ( = 0·01 – 0·10 MPa) are observed.Dedicated to the Memory of Professor Karel P     

Total water content thresholds for shallow landslides,Outer Western Carpathians

Shallow landslides are fairly frequent natural processes which emerge as a result of both rainfall and rapid snowmelt in the Flysch Belt of the Outer Western Carpathians. We estimated the total water content thresholds for the previously defined seven phases of increased landsliding which took place between 1939 and 2010 around the Napajedla meteorological station. The time series were reconstructed on the basis of data from surrounding stations. Rainfalls with the highest intensities (>1 mm/min) were removed from the set. Rainfall of such an intensity primarily causes overland flow and soil erosion and does not contribute to landslide threshold. The snow water equivalent was computed on the basis of the snow height, and possible errors were evaluated as interval estimations. An interval of 10 days before a landslide phase was selected for the total water content threshold. The resulting lower boundary (67.0 mm/10 days) and upper boundary (163.3 mm/10 days) thresholds of water infiltrated into soil during an event shall be part of the prepared online warning system in this area.     

Physical modeling of near-Earth Asteroid (29075) 1950 DA

Near-Earth Asteroid (29075) 1950 DA may closely encounter Earth in 2880. The probability of Earth impact may be as high as 1/300, but the outcome of the encounter depends critically on the physical properties of the asteroid [Giorgini et al., 2002. Science 196, 132-136]. We have used Arecibo and Goldstone radar data and optical lightcurves to estimate the shape, spin state, and surface structure of 1950 DA. The data allow two distinct models. One rotates prograde and is roughly spheroidal with mean diameter 1.16±0.12 km. The other rotates retrograde and is oblate and about 30% larger. Both models suggest a nickel-iron or enstatite chondritic composition. Ground-based observations should be able to determine which model is correct within the next several decades.     

Looking a gift horse in the mouth: Evaluation of wide-field asteroid photometric surveys

It has recently become possible to do a photometric survey of many asteroids at once, rather than observing single asteroids one (or occasionally a couple) at a time. We evaluate two such surveys. Dermawan et al. (Dermawan et al. [2011]. Publ. Astron. Soc. Jpn. 63, S555–S576) observed one night on the Subaru 8.2 m telescope, and Masiero et al. (Masiero, J., Jedicke, R., Durech, J., Gwen, S., Denneau, L., Larsen, J. [2009]. Icarus 204, 145–171) observed six nights over 2 weeks with the 3.6 m CFHT. Dermawan claimed 83 rotation periods from 127 detected asteroids; Masiero et al. claimed 218 rotation periods from 828 detections. Both teams claim a number of super-fast rotators (P < 2.2 h) among main belt asteroids larger than 250 m diameter, some up to several km in diameter. This would imply that the spin rate distribution of main belt asteroids differs from like-sized NEAs, that there are larger super-fast rotators (monolithic asteroids) in the main belt than among NEAs. Here we evaluate these survey results, applying the same criteria for reliability of results that we apply to all results listed in our Lightcurve Database (Warner, B.D., Harris, A.W., Pravec, P. [2009a]. Icarus 202, 134–146). In doing so, we assigned reliability estimates judged sufficient for inclusion in statistical studies for only 27 out of 83 (33%) periods claimed by Dermawan, and only 87 out of 218 (40%) periods reported by Masiero et al.; none of the super-fast rotators larger than about 250 m diameter claimed by either survey received a reliability rating judged sufficient for analysis. We find no reliable basis for the claim of different rotation properties between main belt and near-Earth asteroids. Our analysis presents a cautionary message for future surveys.