Spatial process and data models: Toward integration of agent-based models and GIS

The use of object-orientation for both spatial data and spatial process models facilitates their integration, which can allow exploration and explanation of spatial-temporal phenomena. In order to better understand how tight coupling might proceed and to evaluate the possible functional and efficiency gains from such a tight coupling, we identify four key relationships affecting how geographic data (fields and objects) and agent-based process models can interact: identity, causal, temporal and topological. We discuss approaches to implementing tight integration, focusing on a middleware approach that links existing GIS and ABM development platforms, and illustrate the need and approaches with example agent-based models.     

Primary aragonite and high‐Mg calcite in the late Cambrian (Furongian). Potential evidence from marine carbonates in Oman

Transient aragonite seas occurred in the early Cambrian but several models suggest the late Cambrian was a time of calcite seas. Here, evidence is presented from the Andam Group, Huqf High, Oman (Gondwana) that suggests a transient Furongian (late Cambrian) aragonite sea, characterized by the precipitation of aragonite and high‐Mg calcite ooids and aragonite isopachous, fibrous, cements. Stable carbon isotope data suggest that precipitation occurred just before and during the SPICE (Steptoean Positive Carbonate Isotope Excursion). Aragonite and high‐Mg calcite precipitation can be accounted for if mMg:Ca ratios were around 1.2 given the very high atmospheric CO₂ at that time and if precipitation occurred in warm waters associated with the SPICE. This, together with reported occurrences of early Furongian aragonite ooids from various locations in North America (Laurentia), suggests that aragonite and high‐Mg calcite precipitation from seawater may have been more than just a local phenomenon.     

Characterisation and multifaceted anisotropy assessment of Corvio sandstone for geological CO2 storage studies

We present a comprehensive characterisation of the physical, mineralogical, geomechanical, geophysical, and hydrodynamic properties of Corvio sandstone. This information, together with a detailed assessment of anisotropy, is needed to establish Corvio sandstone as a useful laboratory rock‐testing standard for well‐constrained studies of thermo–hydro–mechanical–chemical coupled phenomena associated with CO₂ storage practices and for geological reservoir studies in general. More than 200 core plugs of Corvio sandstone (38.1 and 50 mm diameters, 2:1 length‐to‐diameter ratio) were used in this characterisation study, with a rock porosity of 21.7 ± 1.2%, dry density 2036 ± 32 kg m^?3, and unconfined compressive and tensile strengths of 41 ± 3.28 and 2.3 ± 0.14 MPa, respectively. Geomechanical tests show that the rock behaves elastically between ～10 and ～18 MPa under unconfined conditions with associated Young's modulus and Poisson's ratio of 11.8 ± 2.8 GPa and 0.34 ± 0.01 GPa, respectively. Permeability abruptly decreases with confining pressure up to ～10 MPa and then stabilises at ～1 mD. Ultrasonic P‐ and S‐wave velocities vary from about 2.8–3.8 km s^?1 and 1.5–2.4 km s^?1, respectively, over confining and differential pressures between 0.1 and 35 MPa, allowing derivation of associated dynamic elastic moduli. Anisotropy was investigated using oriented core plugs for electrical resistivity, elastic wave velocity and attenuation, permeability, and tracer injection tests. Corvio sandstone shows weak transverse isotropy (symmetry axis normal to bedding) of <10% for velocity and <20% for attenuation.     

Fluctuation dissipation in a general circulation model

This paper considers the climate response to step function changes in the solar constant in two versions of a general circulation model with simplified geography. The NCAR CCM0 model is applied to an all-land planet with no topography (Terra Blanda). In one version there is moisture in the air (as well as self-generated clouds) as evaporated from an ideal surface at a fixed 80% of saturation. In the other version there is no moisture in the atmosphere. We examine the decay of natural anomalies in the large-scale temperature field in each model and compare the time dependence of the ensemble average with the average temporal behavior of the response to step function changes in the solar constant. The fluctuation-dissipation theorem of statistical mechanics makes specific predictions about the relationship between the two curves. We conduct the experiments for both versions of the model since the sensitivity is quite different for each. The theorem is found to hold reasonably well in each case.     

A formula describing both magnetic and isotopic blocking temperatures

The following new theorem is proved: the equation E/RT_B =ln(1.781 k₀τ), where E = activation energy, R = the molar gas constant and T_B = blocking temperature, applies equally well to both the isotopic and the magnetic systems in rocks from a cooling orogen. The isotopic model involves first-order loss of daughter, while the magnetic model applies to an assemblage of single-domain grains with constant E. Dodson supplied the original proof that the equation applied to isotopic systems. The well-known superficial similarity between the concepts of isotopic and magnetic blocking is thus given quantitative expression.     

库米什盆地的硝酸盐型钾盐矿床

库米什盆地的硝酸盐型钾盐矿床,是利用~(40)K具有放射性特点,通过航空、地面伽玛能谱测量发现的。本文介绍了具有代表性C矿床的一般地质特征,总结了乌尊布拉克硝酸盐型钾盐矿床地质特征。矿床按其赋存状态可分为固体矿和卤水矿两类。水硝碱镁矾为最主要的工业矿物,共生矿物有钾硝石、钠硝石、杂卤石、芒硝、钠镁矾、石膏、石盐、极少量的泻利盐等。     

Seasonal snowline instability in an energy balance model

The stability properties of a seasonal, one dimensional energy balance climate model are examined. The model contains idealized landsea geography, an interactive moving snowline and high space-time resolution. For a polar land cap surrounded by ocean we find a bifurcation in the seasonal cycle solutions as a function of solar constant leading to qualitatively different climate regimes: one with continental snow-free summers and the other with perennial snow cover over a large area surrounding the pole. In the parameterspace neighborhood of a bifurcation an infinitesimal change in any radiation budget parameter can cause the transition from one state to the other. Of special interest to those planning more elaborate numerical experiments (GCMs) is the result that 10s of seasonal cycles may be necessary for the model to damp out transient effects before settling upon a repeating seasonal cycle if parameter values are such that the solution is near a bifurcation. This latter finding is unexpected, since the longest time scale in the linear version of the energy balance model is about 5 years.