克立格估计的分析解释与协方差函数的代数确定

首先引入利用旋转面作为基函数的函数逼近概念, 在此基础上经过复杂的矩阵推导证明泛克立格法可表示为传统的带权最小二乘多项式拟合与以旋转面作为基函数的函数逼近, 并在一定条件下(随机场高度连续无块金效应) 论证了协方差(即旋转面) 的参数可通过数学分析的方法确定, 给出了以高斯函数为例确定协方差函数的两个准则.      

The International Latitude Service – A Historical Review, From The Beginning To Its Foundation In 1899 And The Period Until 1922

The study of Polar Motion (PM) is associated withthe work of the InternationalLatitude Service (ILS), the International PolarMotion Service (IPMS) and theBureau International de l'Heure (BIH), andthen the International Earth RotationService (IERS). After reviewing briefly thehistory of early PM research, thescientific objective of the ILS including itsrealizing, and the activities of all thecited services and giving information on thePM time series available from mid-19thcentury to the present, important details onthe events and results are presentedover the period until 1922. It is shown, inwhich way the Geodetic Institute Potsdamcontributed to the foundation of the ILS andtook part in its activities through thework of Helmert, Albrecht, Wanach and Mahnkopf.Based on international scientificcooperation, the results were the rectangularcoordinates of the Polar Motion from1890.0 to 1922.7 at 0.1 year intervals, inparticular those derived from the latitudeobservations at independent stations from 1890.0to 1899.8, and those derived fromthe latitude observations at the ILS stationsfrom 1899.9 to 1922.7.     

Reduced emissions from deforestation and forest degradation (REDD): a climate change mitigation strategy on a critical track

Background  

Following recent discussions, there is hope that a mechanism for reduction of emissions from deforestation and forest degradation (REDD) will be agreed by the Parties of the UNFCCC at their 15th meeting in Copenhagen in 2009 as an eligible action to prevent climate changes and global warming in post-2012 commitment periods. Countries introducing a REDD-regime in order to generate benefits need to implement sound monitoring and reporting systems and specify the associated uncertainties. The principle of conservativeness addresses the problem of estimation errors and requests the reporting of reliable minimum estimates (RME). Here the potential to generate benefits from applying a REDD-regime is proposed with reference to sampling and non-sampling errors that influence the reliability of estimated activity data and emission factors.     

Options for accounting carbon sequestration in German forests

Background  

The Accra climate change talks held from 21–27 August 2008 in Accra, Ghana, were part of an ongoing series of meetings leading up to the Copenhagen meeting in December 2009. During the meeting a set of options for accounting carbon sequestration in forestry on a post-2012 framework was presented. The options include gross-net and net-net accounting and approaches for establishing baselines.     

Citizens' perceptions of justice in international climate policy: an empirical analysis

Relying on a recent survey of more than 3400 participants from China, Germany, and the US, this article empirically analyses citizens' perceptions of key guiding principles for sharing mitigation costs across countries, justification of climate policy and trust in climate policy. Our findings suggest that the ranking of the main principles for burden-sharing is identical in China, Germany, and the US: accountability followed by capability, egalitarianism, and sovereignty. Thus, on a general level, citizens across these countries seem to have a common (normative) understanding of fairness. We therefore find no evidence that citizens' (stated) fairness preferences are detrimental to future burden-sharing agreements. In all three countries a majority of citizens considers international climate policy to be justified, but citizens' perceptions differ across specific items and countries. Finally, a substantial portion of citizens in all countries exhibit a lack of trust in international climate agreements.

Policy relevance

Disagreement over the distribution of mitigation costs across countries is blocking current negotiations about a new international climate change agreement to be adopted in 2015. At the heart of this disagreement are different perceptions of distributive justice among those involved in climate policy making. Our findings show that there is no difference in the ranking of fairness principles across citizens in China, Germany, and the US, suggesting that the common ground for crafting a future agreement is larger than expected. In particular, the accountability principle should weigh heavily when deciding on the burden-sharing. In addition, our findings suggest that in order to gain support among citizens, international climate policy may need to take measures to improve trust.     

A new large-eddy simulation model for simulating air flow and warm clouds above highly complex terrain. Part I: The dry model

This paper presents the dry version of a new large-eddy simulation (LES) model, which is designed to simulate air flow and clouds above highly complex terrain. The model is three-dimensional and nonhydrostatic, and the governing equations are sound filtered by use of the anelastic approximation. A fractional step method is applied to solve the equations on a staggered Cartesian grid. Arbitrarily steep and complex orography can be accounted for through the method of viscous topography. The dynamical model core is validated by comparing the results for a spreading density current against a benchmark solution. The model accuracy is further assessed through the simulation of turbulent flow across a quasi two-dimensional ridge. The results are compared with wind-tunnel data. The method of viscous topography is not restricted to moderately sloped terrain. Compared to models using curvilinear grids, it allows this model to be applied to a much wider range of flows. This is illustrated through the simulation of an atmospheric boundary-layer flow over a surface mounted cube. The results show that the dry model version is able to accurately represent the complex flow in the vicinity of three-dimensional obstacles. It is concluded that the method of viscous topography was successfully implemented into a micrometeorological LES model. As will be shown in Part II, this allows the detailed study of clouds in highly complex terrain.     

Paläogezeiten und Erdrotation

Zusammenfassung Gezeitenreibung der Hydrosphäre bewirkt einen Verlust von Rotationsdrehimpuls der Erde, der durch einen Gewinn von Bahndrehimpuls des Mondes ausgeglichen wird. Die Dissipationsrate kann für einen gegebenen Ozean mit Hilfe hydrodynamisch-numerischer Modelle berechnet werden. Die Rückverfolgung der Geschichte des Erde-Mond-Systems erfordert wegen der Änderung der Kontinent-Meer-Verteilung zur Bestimmung des jeweiligen Drehimpulstransfers die Kenntnis der Paläogezeiten. Es werden Ergebnisse (Amplituden, Phasen, Restströme) für Ozeane der Oberen Kreide (vor ca. 70 · 10⁶ Jahren) und des Mittleren Silurs (vor ca. 420 · 10⁶ Jahren) vorgestellt sowie die zugehörigen Änderungen der Rotationsenergie der Erde angegeben.

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Tidal friction of the hydrosphere causes a loss of rotational angular momentum of the Earth that is balanced by a gain of orbital angular momentum of the Moon. The rate of dissipation for a given ocean can be calculated by means of a hydrodynamical-numerical model. Tracing back the history of the Earth-Moon-system, due to the varying distribution of continents and oceans information is needed about the paleotides to determine the transfer of angular momentum. Results (corange-lines, cotidal-lines, residual currents) are presented for oceans of the Upper Cretaceous (70 m. y. b. p.) and the Middle Silurian (420 m. y. b. p.). The corresponding change of the Earth's rotational energy is indicated.

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Résumé La friction des marées de l'hydrosphère fait perdre à la Terre une quantité du moment cinétique angulaire rotationnel compensée par un gain de moment cinétique angulaire orbital de la lune. La distribution des continents et des océans varie. Quand on retrace l'histoire du système Terre-Lune, on a besoin d'informations sur les paléomarées pour déterminer le transfert de moment cinétique angulaire. La dissipation, pour un océan donné, peut être calculée au moyen d'un modèle numérique-hydrodynamique. Des résultats (amplitudes, phases, courants résiduels) sont donnés pour des océans du Créacé supérieur (il y a ca. 70 · 10⁶ années) et du Silurien moyen (il y a ca. 420 · 10⁶ années). Le changement correspondant de l'énergie rotationelle terrestre est indiqué.

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- , . . - -, - . — , — ( 70.10⁶ ) ( 420.10⁶ ), .

     

Simulation of Io’s auroral emission: Constraints on the atmosphere in eclipse

We study the morphology of Io’s aurora by comparing simulation results of a three-dimensional (3D) two-fluid plasma model to observations by the high-resolution Long-Range Reconnaissance Imager (LORRI) on-board the New Horizons spacecraft and by the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). In 2007, Io’s auroral emission in eclipse has been observed simultaneously by LORRI and ACS and the observations revealed detailed features of the aurora, such as a huge glowing plume at the Tvashtar paterae close to the North pole. The auroral radiation is generated in Io’s atmosphere by collisions between impinging magnetospheric electrons and various neutral gas components. We calculate the interaction of the magnetospheric plasma with Io’s atmosphere-ionosphere and simulate the auroral emission. Our aurora model takes into account not only the direct influence of the atmospheric distribution on the morphology and intensity of the emission, but also the indirect influence of the atmosphere on the plasma environment and thus on the exciting electrons. We find that the observed morphology in eclipse can be explained by a smooth (non-patchy) equatorial atmosphere with a vertical column density that corresponds to ∼10% of the column density of the sunlit atmosphere. The atmosphere is asymmetric with two times higher density and extension on the downstream hemisphere. The auroral emission from the Tvashtar volcano enables us to constrain the plume gas content for the first time. According to our model, the observed intensity of the Tvashtar plume implies a mean column density of ∼5 × 10¹⁵ cm⁻² for the plume region.     

A parallel block preconditioner for large-scale poroelasticity with highly heterogeneous material parameters

Large-scale simulations of coupled flow in deformable porous media require iterative methods for solving the systems of linear algebraic equations. Construction of efficient iterative methods is particularly challenging in problems with large jumps in material properties, which is often the case in realistic geological applications, such as basin evolution at regional scales. The success of iterative methods for such problems depends strongly on finding effective preconditioners with good parallel scaling properties, which is the topic of the present paper. We present a parallel preconditioner for Biot’s equations of coupled elasticity and fluid flow in porous media. The preconditioner is based on an approximation of the exact inverse of the two-by-two block system arising from a finite element discretisation. The approximation relies on a highly scalable approximation of the global Schur complement of the coefficient matrix, combined with generally available state-of-the-art multilevel preconditioners for the individual blocks. This preconditioner is shown to be robust on problems with highly heterogeneous material parameters. We investigate the weak and strong parallel scaling of this preconditioner on up to 512 processors and demonstrate its ability on a realistic basin-scale problem in poroelasticity with over eight million tetrahedral elements.     

Rapid mapping in support of emergency response after earthquake events

Earthquakes and other sudden onset natural disasters require quick and efficient emergency response. Earth observation (EO) data can make a valuable contribution to emergency response efforts if provided within hours and at the most days after the event. Mechanisms like the International Charter Space and Major Disasters and the European GMES Emergency Response Service provide the necessary basis for an efficient and rapid provision of EO data and damage mapping. This paper provides an overview of earthquake damage assessment methodologies, their potential and their limitations in a rapid mapping context and outlines a methodology for casualty estimation. Two case studies—the 2010 Haiti earthquake and the 2011 Van (Turkey) earthquake—are presented, where DLR’s Center for satellite-based crisis information (ZKI) provided rapid damage maps using a team-based visual interpretation approach. Additionally, the application of a casualty estimation method in the immediate aftermath of an earthquake is outlined.