西藏植被净初级生产力对气候变化的响应

根据1971-2005年年平均气温、降水量资料．采用Thornthwaite Memorial模型计算了西藏植被净初级生产力（net primary production,NPP）,分析了NPP的空间分布、年际和年代际变化特征,以及未来气候变化对NPP的影响。结果表明,西藏NPP有自东南向西北递减的分布规律。近35a阿里地区西南部、聂拉木、江孜NPP为减少趋势,减幅为11．9～314．2kg·hm^-2·（10a）^-1,以普兰减幅最大;其他各地呈不同程度的增加趋势,增幅为26．8～459．8kg·hm^-2·（10a）^-1,其中拉萨增幅最明显;林芝地区、昌都地区北部、那曲地区NPP呈明显的逐年代增加趋势,阿里地区西南部、聂拉木NPP表现为逐年代减少趋势。就西藏平均而言,20世纪70年代气候“冷干”,NPP偏低;90年代气候“暖湿”,NPP偏高。从设定的气候变化情景来看,“暖湿型”气候对西藏NPP有利,平均增产6％～13％;“冷干型”气候对西藏NPP不利,平均减产6％-14％。未来西藏以“暖湿型”气候为主,到2050年NPP将增加11％～26％。     

About stability of libration points in the restricted photogravitational three body problem

Nonlinear stability of the triangular libration point in the photogravitational restricted three body problem was investigated in the whole range of the parameters. Some results obtained earlier are corrected. The method for proper determination of cases when stability cannot be determined by four order terms of the hamiltonian was proposed.     

See-Erz,Roströhren und verwandte Konkretionen

Zusammenfassung Den Röhrensteinen des Großen Plöner Sees verwandte Bildungen werden an Hand der wichtigsten Literatur beschrieben. Fe- und Mn-Konkretionen — unter diese fallen See-Erze, Roströhren, Fe-Anhäufungen in Seesedimenten u. a. — sind nach dem jetzigen Stande der Forschung im wesentlichen durch Mikroben gebildet oder wenigstens in ihrer Entstehung durch diese Organismen unterstützt, obgleich meistens eine rein chemisch-physikalische Deutung der Prozesse möglich ist. Die Grundzüge der regionalen Verbreitung von See- und Wiesenerzen in Schweden wurden zuerst vonStapff dargelegt und später durchNaumann den neuesten Anschauungen angepaßt. Kalk, Ton und elektrolytreiche Gewässer unterdrücken die Erzbildung. Auch von karbonatreichen Böden und Wässern sind Anhäufungen von Eisenhydroxyd bekannt, aber den schwedischen Massenvorkommen gegenüber geringfügig. Die Entstehung der Roströhren wird näher erläutert. O₂-Abgabe der Pflanzenwurzeln, physikalische Adsorptionsprozesse, wahrscheinlich auch Gerbstoffe und Kalk usw. fällen Fe und Mn aus. Den Röhrensteinen Ähnliche Bildungen sind bei den Wohnröhren vonCorophium beobachtet worden. Auch die Osteokollen gestatten eine Parallele; dennoch handelt es sich dabei um Kalkfällung. Die bekanntesten fossilen Roströhren stammen aus dem Münzenberger Sandstein.     

A model of the gravitational field of Amalthea

Utilizing the topographic model of Jovian moon Amalthea (Stooke, 1994) and supposing that its mass density is constant we derived its basic geometrical and dynamical characteristics. For calculations the harmonic model of topography of the degree and order 18 was selected. The model appears to fit the entire surface to a mean accuracy of a few hundred meters, except in the regions localized around longitudes 0° and 180°. On the basis of the harmonic expansion of the topography we estimated the volume (V = 2.43 ± 0.02 km³) and the mean radius of topographyr ₀ = (79.7 ± 0.2) km. Generalized moments of inertia up to the order 2, principal moments of inertia and orientation of the principal axes with respect to the original reference frame were also calculated. The results show that although Amalthea has extremely irregular shape it may be treated dynamically as an almost symmetric body (B C). Finally, the set of the Stokes coefficients up to the degree and order 9 was evaluated. The results are verified by direct numerical integration.     

Multidimensional economic indicators and multivariate functional principal component analysis (MFPCA) in a comparative study of countries’ competitiveness

Journal of Geographical Systems - The multivariate pluriformity and complexity of economic-geographic space (e.g., cities or countries) are reflected in their empirical multidimensional data...     

Inflation and compactification from Galaxy redshifts?

The distribution of galaxies in the pencil-beam surveys of Broadhurstet al. which proved periodical across 8–10 consecutive steps in a flat dust model withq ₀=0.5 is found to reveal extended periodicity up to 16–17 phase-coherent steps, covering the total sample, in a flat, moderately inflationary model withq ₀=–0.5 (vacuum/dust ratio 2/1). In the latter model the vacuum component helps to reach the critical density and lengthens the expansion time-scale. It is shown that the explanation of the found periodicity as a consequence of space compactification as suggested by G. Paál twenty years ago in connection with apparent quasar periodicities is still possible.     

Floods at the northern foothills of the Tatra Mountains — A Polish-Swiss research project

The present paper introduces the topical area of the Polish-Swiss research project FLORIST (Flood risk on the northern foothills of the Tatra Mountains), informs on its objectives, and reports on initial results. The Tatra Mountains are the area of the highest precipitation in Poland and largely contribute to flood generation. The project is focused around four competence clusters: observation-based climatology, model-based climate change projections and impact assessment, dendrogeomorphology, and impact of large wood debris on fluvial processes. The knowledge generated in the FLORIST project is likely to have impact on understanding and interpretation of flood risk on the northern foothills of the Tatra Mountains, in the past, present, and future. It can help solving important practical problems related to flood risk reduction strategies and flood preparedness.     

藏北牧区牲畜掉膘期温度变化特征

 利用西藏那曲地区1971-2005年日平均气温≤-5℃的初终日、持续时间及期间的负积温、平均气温、最高气温、最低气温等资料,采用气候倾向率等方法分析了近35 a来藏北牧区牲畜掉膘期及期间温度要素的变化趋势和异常年份。结果表明：藏北各牧区牲畜掉膘期开始日均呈现推迟趋势,平均推迟2.1～4.9 d/10 a;终日变化不显著;掉膘期持续时间均呈现缩短趋势。掉膘期间各牧区平均气温呈升高趋势,≤-5℃的负积温为减少趋势。掉膘期持续时间年代际变化呈明显的下降趋势,20世纪90年代掉膘持续时间短,有利于牧业生产。     

Stability of the Triangular Libration Points in the Unrestricted Planar Problem of a Symmetric Rigid Body and a Point Mass

In papers (Godziewski and Maciejewski, 1998a, b, 1999), we investigate unrestricted, planar problem of a dynamically symmetric rigid body and a sphere. Following the original statement of the problem by Kokoriev and Kirpichnikov (1988), we assume that the potential of the rigid body is approximated by the gravitational field of a dumb-bell. The model is described in terms of a 2D Hamiltonian depending on three parameters.In this paper, we investigate the stability of triangular equilibria permissible by the dynamics of the model, under the assumption of low-order resonances. We analyze all resonances of order smaller than four, and we examine the stability with application of theorems by Markeev and Sokolsky. These are the possible following cases: the non-diagonal resonance of the first order with two null characteristic frequencies (unstable); resonances of the first order with one nonzero frequency (diagonal and non-diagonal, stable and unstable); the second-order resonance, which is non-diagonal and stable, and the third-order resonance which is generically unstable, except for three points in the parameters' space, corresponding to stable equilibria.We discuss a perturbed version of Kokoriev and Kirpichnikov model, and we find that if the perturbation is small and depends on the coordinates only, the triangular equilibria persist, except if for the unperturbed equilibria the first-order resonance occurs. We show that the resonances of the order higher than two are also preserved if the perturbation acts.