The rate of climate warming varies on diurnal and seasonal timescales.
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4 by Lambert Conformal Conic map projection with resolution 0.5°×0.Feedbacks between the terrestrial carbon cycle and climate change could affect many ecosystem functions and services, such as food production, carbon sequestration and climate regulation. The Cartesian conductive model transformed from model in Fig. The 3D conductivity distribution in spherical coordinates Electric fields are defined on the middle point of cells′ edges, while magnetic fields are defined naturally on the cell faces, every cell center is assigned with conductivity σĪpparent resistivity and phase profiles computed from (a) homogenous model, (b) 1D layered model under Cartesian and spherical coordinates respectively The whole computational domain including the resistive air is divided into many curved rectangular cells. Staggered finite difference grid for 3D MT forward problem in spherical coordinates. According to real bathometry data, we make the China continent and its adjacent sea model to research the forward difference between spherical and Cartesian coordinates. All the forward calculations are implemented on the blade server in the form of frequency parallel scheme, spherical model usually takes twice time than Cartesian. Under the combined effect of conductivity distribution and the unavoidable deformation, electric fields and apparent resistivities show stronger difference at the place where conductivity contrasts. We compare their forward response such as electric fields and apparent resistivity computed from spherical and Cartesian coordinates respectively. Large scale three-dimensional conductive models with different resolution are built and transformed to their corresponding Cartesian models by Lambert Conformal Conic map projection which can maintain the shape of original spherical model.
#Non uniform grid mapping code#
Taking into account the versatility and convenience, this spherical forward code is developed on the open source ModEM which provides a ready framework for rapid implementation of new application or algorithms. Electric field components defined on curving cell edges are the primary EM field that is computed iteratively utilizing a quasi-minimum residual scheme, with a divergence correction applied periodically. The spherical model is built directly through geographic information like latitude and longitude, and the forward response will be obtained by solving the Maxwell's equations in terms of spherical format.
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In addition, the electric fields are represented by poloidal-toroidal decomposition, then solved based on spherical harmonic and Bessel function to construct the source model that can be used to replace plane wave. We have developed a kind of magnetotellurics forwarding code in spherical coordinates based on staggered grid finite difference method. With more and more magnetotellurics data coming in and the expansion of research area, Cartesian approximation and plane wave assumption may no longer be suitable for the large-scale modeling due to the inevitable Earth curve. Traditionally, magnetotellurics (MT) rests on an assumption that plane wave is incident vertically into flat Earth.