50th Birthday of professor a Zátopek     

Jiři Vaněk 《Studia Geophysica et Geodaetica》1957,1(1):196-196

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A two-stage time series model for monthly hydrological projections under climate change in the Lim River basin (southeast Europe)     

Milan Stojković  Jasna Plavšić  Stevan Prohaska  Dragutin Pavlović  Jovan Despotović 《水文科学杂志》2020,65(3):387-400

ABSTRACT

Climate change projections of precipitation and temperature suggest that Serbia could be one of the most affected regions in southeastern Europe. To prepare adaptation measures, the impact of climate changes on water resources needs to be assessed. Pilot research is carried out for the Lim River basin, in southeastern Europe, to predict monthly flows under different climate scenarios. For estimation of future water availability, an alternative approach of developing a deterministic-stochastic time series model is chosen. The proposed two-stage time series model consists of several components: trend, long-term periodicity, seasonality and the stochastic component. The latter is based on a transfer function model with two input variables, precipitation and temperature, as climatic drivers. The Nash-Sutcliffe model efficiency for the observed period 1950–2012 is 0.829. The model is applied for the long-term hydrological prediction under the representative concentration pathway (RCP) emissions scenarios for the future time frame 2013–2070.  相似文献   

The LMDZ4 general circulation model: climate performance and sensitivity to parametrized physics with emphasis on tropical convection   总被引：3，自引：11，他引：3  

Frédéric Hourdin  Ionela Musat  Sandrine Bony  Pascale Braconnot  Francis Codron  Jean-Louis Dufresne  Laurent Fairhead  Marie-Angèle Filiberti  Pierre Friedlingstein  Jean-Yves Grandpeix  Gerhard Krinner  Phu LeVan  Zhao-Xin Li  François Lott 《Climate Dynamics》2006,27(7-8):787-813

The LMDZ4 general circulation model is the atmospheric component of the IPSL–CM4 coupled model which has been used to perform climate change simulations for the 4th IPCC assessment report. The main aspects of the model climatology (forced by observed sea surface temperature) are documented here, as well as the major improvements with respect to the previous versions, which mainly come form the parametrization of tropical convection. A methodology is proposed to help analyse the sensitivity of the tropical Hadley–Walker circulation to the parametrization of cumulus convection and clouds. The tropical circulation is characterized using scalar potentials associated with the horizontal wind and horizontal transport of geopotential (the Laplacian of which is proportional to the total vertical momentum in the atmospheric column). The effect of parametrized physics is analysed in a regime sorted framework using the vertical velocity at 500 hPa as a proxy for large scale vertical motion. Compared to Tiedtke’s convection scheme, used in previous versions, the Emanuel’s scheme improves the representation of the Hadley–Walker circulation, with a relatively stronger and deeper large scale vertical ascent over tropical continents, and suppresses the marked patterns of concentrated rainfall over oceans. Thanks to the regime sorted analyses, these differences are attributed to intrinsic differences in the vertical distribution of convective heating, and to the lack of self-inhibition by precipitating downdraughts in Tiedtke’s parametrization. Both the convection and cloud schemes are shown to control the relative importance of large scale convection over land and ocean, an important point for the behaviour of the coupled model.  相似文献   

Comparison of three mathematical models for the estimation of 10-day drain discharge     

K. Pandžić  I. Šimunić  F. Tomić  S. Husnjak  T. Likso  D. Petošić 《Theoretical and Applied Climatology》2006,85(1-2):107-115

Summary This paper presents an the evaluation of three mathematical models for the estimation of 10-day drain discharge using weather, pedological and phenological parameters. One model uses modified Palmer’s procedure for the calculation of water balance components and the second two use empirical multiple linear regression. The models have been applied to data of an amelioration experimental field in central Croatia (south-western part of the Pannonian Lowland), where a set of average 10-day air temperature and relative humidity data, average wind speed, cumulative precipitation and drain discharge amounts, insolation and soil moisture data and vegetation indices have been collected. The experiment has been performed during the period 1990–1992. The models have been tested by comparing estimated and observed 10-day drain discharge amounts. All models mainly give acceptable cumulative results although their accuracy depends on the season.  相似文献   

Variable resolution on quasi-uniform grids: linear advection experiments     

M. Rančić  H. Zhang 《Meteorology and Atmospheric Physics》2006,93(1-2):97-114

Summary A couple of different techniques for implementing the variable resolution within numerical models of the atmosphere that use quasi-uniform grids are estimated and compared based on their merit in the simple linear advection experiments. These techniques are: grid stretching, Schmidt transforming and grid overlapping. The quasi-uniform grids are: a conformal cubic and an octagonal grid. The techniques for the variable resolution are evaluated from the perspective of their effects on numerical solution and the practicality of their application. Our analysis suggests that the grid stretching is for now the most optimal choice. However, a special form of grid overlapping is presented that has potential to become a viable alternative in the future.  相似文献   

Trace Metal Solid State Speciation in Aerosols of the Northern Levantine Basin,East Mediterranean   总被引：3，自引：0，他引：3  

Mustafa Koçak  Nilgun Kubilay  Barak Herut  Malcolm Nimmo 《Journal of Atmospheric Chemistry》2007,56(3):239-257

An established three stage sequential leach scheme was applied to a series of selected high volume aerosol samples (n = 35) collected from the Turkish Eastern Mediterranean coastline (Erdemli). Samples were selected according to their air mass back trajectory history to reflect the contrasting mixtures of aerosol material present in the Eastern Mediterranean marine aerosol. Two populations were adopted, those samples which were classed as “anthropogenic” and those which were “Saharan” dominated aerosol populations. Applying the three stage leach it was possible to define the proportion for each of the considered metals (Al, Fe, Cu, Pb, Cd, Zn and Mn) present in the (a) “exchangeable” (b) “carbonate / oxide” and (c) “refractory” phases, representing novel solid state aerosol speciation data for this marine system. Clear trends were established, conforming with data from previous studies with mainly crustal derived metals (Al and Fe) being present in the refractory phases (Al > 88%; Fe > 84%) and those influenced by anthropogenic sources being dominating in the exchangeable phase, although for these metals the variability was comparatively high (12–64%; 19–85%; 40–100% for Zn, Pb and Cd, respectively). For the majority, greater exchangeable fractions were present the lower the crustal source contribution to the aerosol population, whereas the “refractory” fraction exhibited contrasting behaviour. This was illustrated by the novel application of the mixing diagram, presenting each of the three speciation stages against the corresponding percent anthropogenic contribution to each collected sample. Zn, Pb and Cd all illustrated progressive decrease in the percent exchangeable with increasing crustal contribution to the aerosol population. The percent exchangeable was discussed in terms of its use to represent the upper limit of the bioavailable fraction of metal associated with the aerosol, post deposition. The mixing diagram approach enabled the prediction of the residual fractions for Cd, Pb and Zn (41 ± 4%; 62 ± 4% and 82 ± 5%, respectively,) in Saharan end-member material.  相似文献   

Decoupling of arsenic and iron release from ferrihydrite suspension under reducing conditions: a biogeochemical model     

André Burnol  Francis Garrido  Philippe Baranger  Catherine Joulian  Marie-Christine Dictor  Françoise Bodénan  Guillaume Morin  Laurent Charlet 《Geochemical transactions》2007,8(1):12

High levels of arsenic in groundwater and drinking water are a major health problem. Although the processes controlling the release of As are still not well known, the reductive dissolution of As-rich Fe oxyhydroxides has so far been a favorite hypothesis. Decoupling between arsenic and iron redox transformations has been experimentally demonstrated, but not quantitatively interpreted. Here, we report on incubation batch experiments run with As(V) sorbed on, or co-precipitated with, 2-line ferrihydrite. The biotic and abiotic processes of As release were investigated by using wet chemistry, X-ray diffraction, X-ray absorption and genomic techniques. The incubation experiments were carried out with a phosphate-rich growth medium and a community of Fe(III)-reducing bacteria under strict anoxic conditions for two months. During the first month, the release of Fe(II) in the aqueous phase amounted to only 3% to 10% of the total initial solid Fe concentration, whilst the total aqueous As remained almost constant after an initial exchange with phosphate ions. During the second month, the aqueous Fe(II) concentration remained constant, or even decreased, whereas the total quantity of As released to the solution accounted for 14% to 45% of the total initial solid As concentration. At the end of the incubation, the aqueous-phase arsenic was present predominately as As(III) whilst X-ray absorption spectroscopy indicated that more than 70% of the solid-phase arsenic was present as As(V). X-ray diffraction revealed vivianite Fe(II)₃(PO₄)₂.8H₂O in some of the experiments. A biogeochemical model was then developed to simulate these aqueous- and solid-phase results. The two main conclusions drawn from the model are that (1) As(V) is not reduced during the first incubation month with high Eh values, but rather re-adsorbed onto the ferrihydrite surface, and this state remains until arsenic reduction is energetically more favorable than iron reduction, and (2) the release of As during the second month is due to its reduction to the more weakly adsorbed As(III) which cannot compete against carbonate ions for sorption onto ferrihydrite. The model was also successfully applied to recent experimental results on the release of arsenic from Bengal delta sediments.  相似文献   

An immersed boundary method for compressible multiphase flows: application to the dynamics of pyroclastic density currents     

Mattia de’ Michieli Vitturi  Tomaso Esposti Ongaro  Augusto Neri  Maria Vittoria Salvetti  François Beux 《Computational Geosciences》2007,11(3):183-198

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Spectral analysis of the “Koshava” wind     

M. Unkašević  I. Tošić  M. Obradović 《Theoretical and Applied Climatology》2007,89(3-4):239-244

Summary “Koshava” is a gusty wind of changeable intensity, blowing from a south-easterly direction, over Serbia, Romania and Bulgaria. It is caused by the interaction between the synoptic circulation and the orography of the Carpathian and the Balkan mountains. This paper analyzes wind data measured at the Belgrade-Observatory during the longest period of consecutive days of “Koshava” which occurred from 14 January to 13 February 1972. Mean hourly wind speed data has been examined using spectral analysis. The power spectra are calculated using autocorrelation spectral analysis, the multi-taper method and wavelet transform. The maximum of which is about 122 h (5 days) corresponds to the time span of synoptic processes.  相似文献   

A Method to Determine the Solar Synodic Rotation Rate and the Height of Tracers     

Roša  D.  Vršnak  B.  Božić  H.  Brajša  R.  Ruždjak  V.  Schroll  A.  Wöhl  H. 《Solar physics》1998,179(2):237-252

The dependence of the measured apparent synodic solar rotation rate on the height of the chosen tracer is studied. A significant error occurs if the rotation rate is determined by tracing the apparent position of an object above the photospheric level projected on the solar disc. The centre-to-limb variation of this error can be used to determine simultaneously the height of the object and the true synodic rotation rate. The apparent (projected) heliographic coordinates are presented as a function of the height of the traced object and the coordinates of its footpoint. The relations obtained provide an explicit expression for the apparent rotation rate as a function of the observed heliographic coordinates of the tracer, enabling an analytic least-squares fit expression to determine simultaneously the real synodic rotation rate and the height of the tracer.  相似文献