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一个模型网格究竟是什么?

我刚开始阅读有关建模的一些笔记,似乎无法理解1°x1°网格或2.5°网格或1/4°网格。我知道这是有关决议的区域模式运行。但是当这样的直线,“2.5°网格值归档”,到底我应该做的吗?

回答

模型是系统的简化表示。而不是试图模型到微观层面的一切,或者是向量,我们经常跨地理区域聚集现象,为了简化计算,失去一点点准确度和精密度。英国,所以如果我想模型大约跨越8度;W - 2度;E, 50度;N - 60度;N,这是一个面积10度;x 10度;。我可以分割成400个细胞,每个0.5度;x0.5°。从西南角,我模型8度地区;W - 7.5度;W x 50度;N - 50.5度;N作为一个单一的同质区域,没有变化。和相同的其他399个细胞(8度;W - 7.5度;W x 50.5度;N-51° N等等一直到1.5度;E-2° E x 59.5度;N-60° N)。这将是一个0.5度;网格。注意,gridcell不重叠,并且他们完全覆盖感兴趣的区域。 (in mathematical terms, they are exclusive and exhaustive - every point of interest is in exactly one gridcell). That can create vast amounts of data - particularly if I'm doing this for the whole world, at second-by-second resolution for ten years, for a few hundred variables of interest. And no one will ever need that amount of precision from my results. So I aggregate up to a more coarse grid: so that I take 25 grid squares that form a larger square, and aggregate each of my statistics of interest in them. So now my area 8°W-7.5°W x 50°N-50.5°N is just one of 25 cells in a square in the coarser grid which spans 8°W-5.5°W x 50°N-52.5°N, and I report statistics for 16 cells in a 2.5° grid, rather than 400 cells in a 0.5° grid. Exactly how that aggregation is done, will vary for each statistic: * If it's a minimum overnight temperature, then I'll take the minimum across all 25 0.5° gridcells, to give the minimum overnight temperature for the 2.5° grid cell that consists of those 25. * If it's an average rainfall, I'll take an average. * If it's insolation per unit area, and I'm interested in insolation per unit land area, then I'll take a weighted average of insolation, weighting by the proportion of each 0.5° gridcell that contains land. And then I'll have modelled on a 0.5° grid, and archived on a 2.5° grid Here, for illustration, is Britain in a 100km grid: [![enter image description here][1]][1] <sub>[source][2]</sub> If I wanted to aggregate that to a 200km grid, then the four squares in the bottom-left corner, SQ, SR, SV, SW, would be combined into a single grid cell. And SS, ST, SX, SY would be combined into another grid cell. And so on. [1]: http://i.stack.imgur.com/9Ujua.gif [2]: http://www.colorado.edu/geography/gcraft/notes/coordsys/coordsys.html

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\ begingroup美元为什么你把日晒的加权平均,但普通的平均降雨量呢?你提出一个equirectangular网格,这不是等积,所以任何变量的计算平均需要权衡。 \ endgroup美元
- - - - - -gerrit ♦
2016年1月5日,在40

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