On the origin of the fourth zonal geopotential harmonic     

Milan Burša 《Studia Geophysica et Geodaetica》1994,38(1):1-6

Summary It has been proved that the fourth geopotential (Stokes) parameter J₄ of the actual Earth can be explained by its long-term rotational distortions. However, this is not the case of the sixth zonal prameter J₆; its origin should be explained geophysically in another way.Dedicated to the Memory of Professor Karel P  相似文献   

Incompatible magnetic behaviour of fine-grained natural haematite samples prepared in similar ways     

Eduard Petrovský  Mark J. Dekkers  Vladimír Kropáček  Pavel Hejda  Tomáš Zelinka 《Studia Geophysica et Geodaetica》1994,38(1):46-56

Summary The results of a magnetic study of two batches of sized natural haematite fractions (from Kada, Czech Republic) are reported. One of the sample batches was prepared by ultrasonic micro precision sieving in propanon (acetone), the other in ethanol (alcohol). Surprisingly, the magnetic behaviour of the ethanol-sieved fractions was much softer (e.g. H_cr 20 kA/m) as compared with the propanon-sieved fractions (H_cr > 200 kA/m). Thermomagnetic measurements suggest a maghemite portion is present in the material used for the preparation of the ethanol-sieved samples. Possible causes of this puzzling behaviour are discussed. However, no definite conclusion can be drawn on the basis of the data presently available.Presented at 3rd Biennial Meeting on New Trends in Geomagnetism, Smolenice Castle, West Slovakia, June 22–29, 1992.  相似文献   

Gravitational potential energy of terrestrial planets     

Milan Burša  Ondřejka Hovorková 《Studia Geophysica et Geodaetica》1994,38(3):246-255

Summary The gravitational potential energies of Mercury, Venus and Mars have been computed on the basis of density models and compared to that of the Earth. It has been stated that the specific potential energy per unit mass is very close as regards the pair Earth and Venus, as well as the pair Mercury and Mars.Dedicated to the Memory of K. P  相似文献   

Zur Limnologie der Seen Südostlettlands     

Bruno Bérzinš 《Aquatic Sciences - Research Across Boundaries》1949,11(3-4):583-607

Ohne Zusammenfassung  相似文献   

Развитие метеорологии в чехословакии, начиная с 1945 года     

Mikuláš Konček 《Studia Geophysica et Geodaetica》1960,4(2):111-118

Адрес: Trnavská cesta 1, Bratislava.  相似文献   

Stone pillar rockfall in Danxia landform area,Mt. Langshan,Hunan Province,China   总被引：1，自引：1，他引：0  

Luobin Yan  Zheng Hu  Milica Kašanin-Grubin  Vladimir Greif  Zhi Chen 《自然地理学》2016,37(5):327-343

A typical Danxia stone pillar, Leipishi I, in the World Natural Heritage site at Mt. Langshan, China, collapsed on 2 November 2009. To understand the mechanism controlling this rockfall event, uniaxial compressive strength, tensile strength, resistance against sulfuric acid, and freezing and thawing properties were analyzed from 44 sandstone and conglomerate cores collected from the Lanlong Formation, the only exposed formation on Mt. Langshan. In addition, four rock slices were created for analysis under a polarizing microscope. A detailed reconstruction of the geometry and restraint conditions of the stone pillar in place before the rockfall occurred permitted an estimation of the stress state before collapse using 3D finite-element code. The results show that the rapid retreat of soft, intercalated rock layers due to weathering can profoundly change the stress state within the rock body, causing compressive or tensile stresses to rise above compressive or tensile strengths in specific sections of a rock body, and causing partial or complete collapse.  相似文献   

A Review of the Methods and Controls of Soil Weathering Rates     

Huang Laiming  Shao Ming&#x  an  Jia Xiaoxu  Zhang Ganlin 《地球科学进展》2016,31(10):1021-1031

The study of soil weathering processes College of Resources and Environment, rates and the associated influencing factors is crucial for understanding of the feedbacks between soil and environment, which will provide a basis for predicting soil behavior and evolution trend in the ecosystem under natural and anthropogenic forcings. This is also important for the effective management of soil resources. This article reviewed the methods for measuring soil weathering rates (including simulating leaching experiment, model calculation, isotope technique, element depletion and geochemical mass balance) and the influencing factors (including climate, organism, parent material, relief, time and human activities). In view of the serious degradation of soil resources, we proposed the challenge and opportunity of the research of soil weathering. The future study should focus on the critical processes, rates and the associated environmental thresholds of soil weathering under varying natural conditions and intensive human perturbations, including the establishment of the quantitative relationship between the weathering rates calculated by different methods, the analysis and interpretation of synergistic effects among multiple influencing factors, and the modeling and prediction of changing tendency of weathering rates under the impacts of both climatic changes and human activities, in order to guide the sustainable management of soil resource and mitigation of global change.  相似文献   

Comparative Analysis of Risk Assessment of Landslides and Debris Flows of China in 2000 and 2010     

Liu Xilin  Miao Cheng  Tian Chunshan  Qiu Jin&#x  an 《地球科学进展》2016,31(9):926-936

Landslides and debris flows occurr in China frequently and cause disastrous losses of life and property. The risk assessment of landslides and debris flows and their spatial variations were comparatively analyzed in this paper, which has great significance for disaster prevention. This article selected 1 km×1 km grid as the assessment unit and with support of GIS technique, analyzed landslide and debris-flow risk distribution and their spatial variations from 2000 to 2010. The research results indicated that the spatial distribution of risk classes in 2000 and 2010 was obviously discrepant. Overall, taking the Heihe-Tengchong population density line as the boundary, the west of the line is mainly low risk area; the east of the line is mainly high risk area. Compared with the risk of 2000, the risk values of 2010 increased, with the high risk area and low risk area enlarged, moderate risk area reduced. The moderate risk area is the most unstable and sensitive risk area, and its risk class variation is significant. However, China is not a region with the high risk of landslide and debris-flow hazard at present. In the following next 10 years, the risk of landslides and debris flows in China will continue to increase.  相似文献   

Energy and CO<Subscript>2</Subscript> exchanges and influencing factors in spring wheat ecosystem along the Heihe River,northwestern China     

Shuchen Sun  Ming’an Shao  Hongbei Gao 《Journal of Earth System Science》2016,125(8):1667-1679

Spring wheat (Triticum aestivum Linn.) is an important crop for food security in the desert-oasis farmland in the middle reaches of the Heihe River in northwestern China. We measured fluxes using eddy covariance and meteorological parameters to explore the energy fluxes and the relationship between CO₂ flux and climate change in this region during the wheat growing seasons in 2013 and 2014. The energy balance closures were 70.5% and 72.7% in the 2013 and 2014 growing season, respectively. The wheat ecosystem had distinct seasonal and diurnal dynamics of CO₂ fluxes with U-shaped curves. The accumulated net ecosystemic CO₂ exchanges (NEE) were -111.6 and -142.2 g C/m² in 2013 and 2014 growing season, respectively. The ecosystem generally acted as a CO₂ sink during the growing season but became a CO₂ source after the wheat harvest. A correlation analysis indicated that night-time CO₂ fluxes were exponentially dependent on air temperature and soil temperature at a depth of 5 cm but were not correlated with soil-water content, water-vapour pressure, or vapour-pressure deficit. CO₂ flux was not correlated with the meteorological parameters during daytime. However, irrigation and precipitation, may complicate the response of CO₂ fluxes to other meteorological parameters.  相似文献   

Waterspouts in the Eastern Adriatic from 2001 to 2013     

Tanja Renko  Josipa Kuzmić  Vinko Šoljan  Nataša Strelec Mahović 《Natural Hazards》2016,82(1):441-470

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