Parametrization of turbulent fluxes over inhomogeneous landscapes   总被引：1，自引：0，他引：1  

G. N. Panin  Ch. Bernhofer 《Izvestiya Atmospheric and Oceanic Physics》2008,44(6):701-716

Reasons for the nonclosure of the heat balance in the atmospheric boundary layers over natural land surfaces are analyzed. Results of measuring the heat-balance components over different land surfaces are used. The Cabauw (Netherlands) data (obtained throughout 1996 over a grass surface with intermittent shrubs and single trees) and the data from the Anchor station in Germany (measured over coniferous forest in 2000–2001) are analyzed. In all, the analysis involves about fifty thousand independent values of the heat-balance components measured in the experiments, which should be indicative of the reliability of the results obtained in the paper. The data have shown that the heat balance is not closed and the imbalance is 50–250 W/m². The sum of the latent and sensible heat fluxes λE + H = STF is found to be systematically smaller than the difference between the net radiation and the heat flux into the ground R _n ? G. It is shown that the main cause of a systematic heat imbalance in the atmospheric boundary layers over inhomogeneous land surfaces is that the methods of surface-flux measurement and estimation are based on the theory that requires the hypothesis of stationarity and horizontal homogeneity. Direct data analysis has shown that the heat imbalance increases with landscape inhomogeneity. In the paper, a parametrization of the heat imbalance is carried out and the coefficient k _f (z ₀ ^ef /L ^ef ) is introduced as a measure of inhomogeneity. For this, data from the experiments FIFE, KUREX, TARTEX, SADE, etc., are also used. Empirical formulas are presented to refine the results of direct measurements and calculations of surface fluxes over natural (inhomogeneous) land surfaces from profile and standard (using bulk parametrizations) data. These formulas can also be used to determine surface fluxes over inhomogeneous underlying land surfaces in order to take into account so-called subgrid-scale effects in constructing prediction models.  相似文献   

International Conference and Young Scientists School CITES-2005     

A. V. Kislov  G. N. Panin 《Water Resources》2005,32(6):698-699

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On the parameterisation of evaporation and sensible heat exchange for shallow lakes   总被引：2，自引：0，他引：2  

G. N. Panin  A. E. Nasonov  Th. Foken  H. Lohse 《Theoretical and Applied Climatology》2006,85(3-4):123-129

Summary This paper demonstrates that typical air–sea interaction models can be transferred to shallow water conditions and lakes including a depth dependent function. As depth decreases, it is assumed that exchange conditions increase. From our results it follows that the model without the shallow water correction underestimates the latent and sensible heat fluxes of a lake by about 20%. This was shown through the comparison of the model with eddy covariance data for a shallow lake during the LITFASS-98 experiment in Germany. Furthermore, data selection according to the fetch and footprint conditions is presented. These models are also useful for gap filling procedures at measuring stations over lakes with limited fetch conditions in selected directions.  相似文献   

Inhomogeneity of the Land Surface and Problems in theParameterization of Surface Fluxes in Natural Conditions   总被引：1，自引：0，他引：1  

G. N. Panin  G. Tetzlaff  A. Raabe 《Theoretical and Applied Climatology》1998,60(1-4):163-178

Summary Eddy correlation techniques to determine the turbulent fluxes of heat, moisture and momentum in the near-surface atmospheric layer rely on the Monin-Obukhov similarity theory, which requires stationarity and horizontal homogeneity. Experiments at specially selected sites over land and particularly over sea are used to develop this concept. Recent experiments, deliberately conducted in non-ideal conditions, show an underestimation of turbulent fluxes. Results from the field experiments FIFE, KUREX, TARTEX and SADE, point to a relationship between the underestimation of turbulent fluxes and terrain inhomogeneity. In order to systematically correct for this effect a scheme is suggested which uses fetch lengths of different types of surface in the sites surrounding the environment. In addition, horizontal differences in atmospheric stability above different surfaces are included in the correction scheme. This scheme might be useful for the design of validation experiments in non-homogeneous terrain. Received April 9, 1997 Revised July 16, 1997  相似文献   

Upper Cretaceous Magmatic Series and Associated Mineralisation in the Carpathian – Balkan Orogen     

Tudor BERZA  Emil CONSTANTINESCU  SLerban–Nicolae VLAD 《Resource Geology》1998,48(4):291-306

Abstract: The Alpine Orogen contains in South East Europe, from the Carpathians to the Balkans–Srednogorie, an Upper Cretaceous, ore bearing igneous belt: a narrow elongated body which runs discontinously from the Apuseni Mountains in the North, to the western part of the South Carpathians (Banat) in Romania, and further South to the Carpathians of East Serbia and still further East to Srednogorie (Bulgaria). This results in a belt of 750 km/30–70 km, bending from N-S in Romania and Serbia, to E-W in Bulgaria. Using the well established century-old terminology of this region, we describe it in this paper as the Banatitic Magmatic and Metallogenetic Belt (BMMB). Plate tectonics models of the Alpine evolution of South East Europe involve Mesozoic rifting, spreading and thinning of the continental crust or formation of oceanic crust in the Tethian trench system, followed by Cretaceous-Tertiary convergence of Africa with Europe and opening of Eastern Mediterranean and Black Sea troughs. The result of successive stages in the collision process is not only the continental growth of Europe from N to S by the docking of several microplates formerly separated from it by Mesozoic palaeo–oceans, but also the rise of mountain belts by overthickening of the crust, followed by orogenic collapse, lateral extrusion, exhumation of metamorphic core complexes and post-collisional magmatism connected to strike-slip or normal faulting. The BMMB of the Carpathian-Balkan fold belt is rich in ore deposits related to plutons and/or volcano-plutonic complexes. Serbian authors have proposed an Upper Cretaceous Paleorift in Eastern Serbia for the Timok zone and some Bulgarian geologists have furnished geologic, petrological and metallogenetic support for this extensional model along the entire BMMB. The existence and importance of previous westwards directed subductions of Transilvanides (=South Apuseni = Mure? Zone) and Severin-Krajina palaeo–oceans, popular in Roman ian literature, seems to have little relevance to BMMB generation, but the well documented northwards directed subduction of the Vardar-Axios palaeo–ocean during Jurassic and Lower Cretaceous is a good pre-condition for the generation, during the Upper Cretaceous, of banatitic magmas in extensional regime, by mantle delamination due to slab break–off. Four magmatic trends are found: a tholeiitic trend, a calc-alkaline trend, a calc-alkaline high–K to shoshonitic trend and, restricted to East Srednogorie, a peralkaline trend. For acid intrusives, the typology is clearly I-type and magnetite–series, pointing to sources in the deep crust or the mantle; however, some high ⁸⁷Sr/⁸⁶Sr ratios recorded in banatites prove important contamination from the upper crust. The calc-alkaline hydrated magmas, most common for banatitic plutons, can be considered as recording three stages of evolution: more primitive – the monzodioritic, dioritic to granodioritic trend (S Apuseni, S Ba–nat, Timok, C and W Srednogorie); more evolved – the granodioritic-granitic trend (N Apuseni, N Banat, Ridanj–Krepoljin); the alkaline trend (E and W Srednogorie, western part of N Banat). Correlating the composition of the host plutons with the types of mineralisation, several environments can be found in the BMMB, function of timing of fluid separation (porphyry versus non-porphyry environments), depth of emplacement, size of intrusion and geology of intruded rock pile, biotite versus hornblende crystallisation, involving the evolution of K/Na ratio in fluids, i. e. development of potassic and phyllic alteration zones: a) non-porphyry environment with granodioritic to granitic magmas, plutonic level, skarn mineralisation prevails; b) porphyry environment with monzodioritic or dioritic to granodioritic magmas, subvolcanic–hypabyssal–plutonic level; porphyry Cu with skarn halo at hypabyssal-subvolcanic level; c) porphyry environment with monzodioritic or dioritic to granodioritic magmas, volcano-plutonic complexes with porphyry copper plus massive sulfide mineralisation at subvolcanic-volcanic level; d) non-porphyry environment with magmas of alkaline tendency, volcanic level, vein (“mesothermal” and “epithermal”) mineralisation.  相似文献   

Transformation of a border region: dispersed agricultural communities in Brasov County, Romania     

Nicolae Muica  Lesley Roberts  David Turnock 《GeoJournal》1998,46(3):305-317

A most distinctive feature of the settlement pattern of the Brasov area is the extreme dispersal of mixed farming encountered in the western extreme of the county to the north and south of Zarnesti: the Bran and Poiana Marului areas. Here a system of peasant subsistence farming developed in a political borderland between the Habsburg and Ottoman Empires. Despite feudal pressures, the peasantry took all available opportunities to extend their independence including elaborate transhumance systems. And after seeing transfrontier commerce as a source of plunder, in the tradition of Balkan highway robbery within relatively unregulated spaces, the peasantry has profited through employment in factories, particularly during the communist period. However, the current recession in manufacturing is throwing the rural population back on limited land resources. Although farming assumes an important subsistence role which contributes to stability, the long-term survival of these communities will depend on new sources of income. Rural tourism has considerable potential and a promising start has been made in Bran. There are, however, constraints on the further development of the business and great attention will have to be given to the conservation of the environment in both the Bucegi Mountains and the Piatra Craiului where national park status is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

On the planar syzygy solutions of the 3-body problem     

Florin Nicolae Diacu 《Celestial Mechanics and Dynamical Astronomy》1989,46(2):119-128

Relations between the rectilinear, collinear and syzygy solutions of the N-body problem are first pointed out. It is shown that, along a solution, the set of the non-collinear syzygy configuration instants is formed by isolated points. Then we restrict the study to the planar 3-body problem and prove that for Dirichlet-stable solutions, a non-syzygy solution cannot be as close as possible to a syzygy one. It is also true that, in the case of a syzygy solution, the orbit of one particle crosses the line of the other two and can not be tangent to this line in the transition point. Finally we prove that the set of initial conditions leading to non-collinear syzygy solutions is non-empty and open.  相似文献   

Evolution-EM signals before earthquakes in terms of mesomechanics and complexity     

K. Eftaxias  V.E. Panin  Ye.Ye. Deryugin 《Tectonophysics》2007,431(1-4):273

MHz-to-kHz electromagnetic (EM) anomalies have been detected worldwide over time intervals ranging from a few days to a few hours prior to near-surface earthquakes (EQs) that have occurred on land with magnitude approximately six or larger. The MHz radiation systematically appears earlier than the kHz. Laboratory experiments on rock samples reveal a similar change in the frequency content during progressive deformation, i.e. the emissions exhibit a frequency shift from MHz to kHz just before failure of the samples. Herein, we attempt to associate these consecutively emerging MHz and kHz modes of the pre-fracture EM emission with successive distinct stages of the fracture preparation process and the associated fracture mechanisms. We base our approach on synergetic principles of physical mesomechanics. A universal principle of physical mesomechanics is that the plastic deformation of a solid is related to its loss of shear stability at the micro-, meso-, and macroscale levels. Global fracture is determined by the mechanism controlling the development of macroscale bands of localized deformation associated with meso- and microscale relaxation processes. The major result we obtain is that the shift from MHz to kHz EM activity may signal the transition of plastic flow localization from the mesoscale to the macroscale, culminating in global fracture. A complexity measure (Approximate Entropy) and a persistency–anti-persistency measure (Hurst exponent) also give evidence of a two stage-model of EQ preparation process: significant complexity decrease and accession of persistency can be confirmed in the strong kHz EM activity that emerges in the tail of the pre-seismic EM activity. Laboratory experiments on rock samples reveal similar symptoms of an imminent global instability.  相似文献   

Air-sea interaction including a shallow and coastal zone     

Gennady N. Panin  Thomas Foken 《Journal of Atmospheric & Ocean Science》2005,10(3):289-305

We performed special experimental and theoretical research concerning the energy--mass exchange process in shallow waters, which took into account the influence of the basin depth on the evaporation and sensible heat exchange. Data was obtained from deep water basins, as well as from shallow waters, at an open sea, as well as in its coastal zone. A new parameterization model of evaporation and friction velocity from shallow water surfaces under different wind velocities was investigated. Results of models and measurements of the energy/mass exchange intensity of a small shallow lake (LITFASS-experiments) were compared. The validation of these models with the eddy-covariance measurements of the LITFASS-98 and LITFASS-2003 experiments showed good results for the wind sector, with good fetch conditions. Therefore, the models examined may be used for calculating the evaporation of lakes where a standard data set of wind velocity, air and water temperature, air moisture and the depth of the lake is available. It should be remembered that in a coastal zone the roughness of the water surface is transformed and therefore there are additional calculation difficulties for the intensity of the energy-mass exchange. Based on our experimental data of the basin depth influence on the water-atmosphere exchange, a new model for the calculation of the energy-mass exchange in a coastal zone was developed. Our new model in combination with the empirical dependence for the calculation of the energy-mass exchange in a coastal zone allows calculation of the momentum, heat and humidity fluxes values at different distances from a shore.  相似文献   

Coping strategies in rural areas of the Buzau Sub–Carpathians     

Nicolae Muica  David Turnock  Veselina Urucu 《GeoJournal》2000,50(2-3):157-172

This paper focuses on the Sub–Carpathian region which has traditionally maintained a large rural population and is today suffering acute economic and social stress. During the present transition phase the rural population is struggling to survive by combining elements of the modern and traditional economies and research has been undertaken to clarify a range of household strategies. After profiling the communes of the Buzau Carpathians the problem is tackled at two levels on the basis of questionnaire work carried out during 1998–1999. First there is a general overview to outline conditions in Patarlagele commune, including some local contrasts between settlements on main transport axis along the Buzau valley and those in the hills and side valleys. Second there is a consideration of in-depth profiles of specific households in villages in the wider area including Panatau as well as Patarlagele commune. It remains to be seen to what extent the district will be able to safeguard its social capital when growth resumes in large towns especially Brasov and Buzau with which Patarlagele has the best contacts. It is also an open question how far the remoter settlements will retain a viable population, assuming that the services remain relatively poor while disadvantage persists with regard to both employment opportunities and physical security. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献