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参数化模型中表示什么?(语义)

我知道WRF有许多不同的用途和选项,从大气化学与火灾使用,等等。代表一个参数化的什么?例如,在WRF-Chem,化学被认为是参数化?如果不是,区分从参数化机制?光解是参数化吗?生物排放参数化?

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中定义的(AMS术语表)[1],一个或多个过程的参数化是一种简化模型。一般我添加一个参数化模型中添加了一个错误,增加了不确定性的结果。在大多数情况下,参数化不是来源于物理定律,而是适合数据。这些简化为不同的原因。你可能知道下面的例子,这个答案可能是短;-)但是我增加了他们对其他读者可能不会意识到它们的存在。# # # #参数化由于空间约束当我们模型的气象和大气化学过程在一个特定的领域,我们该域分割成单个网格细胞的大小,如网格细胞10公里x 10公里大小。一些大气过程的空间扩展低于网状细胞,如小尺度湍流和云小于10公里。这些东西不能显式计算模型(如果我们减少模型分辨率除外)。因此,我们近似这些事情发生在一个空间规模低于10公里。这些近似表示为参数化。 ## Parameterizations due to computing effort ## When we consider processes such as **particle formation, growth, and coagulation** we could consider every particle or even every molecule in a model. However, in real world atmospheric applications we have too much particles than we could consider them individually. Therefore, we need to calculate the growth of particles on the base of some parameters and apply it on (log-normal) particle number/volume/... distributions. ## Parameterizations due to missing and condensed information ## **Biogenic emissions** are a nice example. We do not know exactly where which trees and plants are located (and which atmospheric conditions like humidity and temperature prevail). For some regions we know it: e.g. for the city of Hamburg there is a detailed (non-public) tree inventory existing. When we do not have this information and work in a gridded domain (i.e. 10 km x 10 km) we need to make a simplified assumption - such as 10% of the grid cell ground is covered by urban area, 30% by grassland, 10% by desert and 50% by forest (of which 70% are pine trees and 30% other trees). From this information and the average ground level temperature and humidity we need to estimate the amount of various emitted volatile organic compounds. Doing this, is a parameterizations because we over-simplify the actual real world. ## But ## From my feeling I would describe a process representation in a model as explicit/non-parameterized when it is included according to the best current/state-of-the-art knowledge. In contrast, when it is considerably simplified, I would denote it as a parameterization. **However**, when we presented **gas phase chemical processes** by differential equations - like as it is done in the gas phase chemistry mechanisms of chemistry transport models -, I would not consider it as parameterizations because due to a large number of identical molecules (and the law of large numbers - probably) we do not actually introduce a large error. [1]: http://glossary.ametsoc.org/wiki/Parameterization

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