[论文解读] The consistency evaluation of the climate version of the Eta regional forecast model developed for regional climate downscaling

I. A. Pisnichenko, T. A. Tarasova|arXiv (Cornell University)|Sep 13, 2007

Climate variability and models被引用 1

一句话总结

本研究评估了基于Eta数值天气预报模型的动态降尺度区域气候模型（RCM）在南美洲（1960–1990年）40公里分辨率下的一致性，该模型由HadAM3P全球气候模型输出驱动。分析结果表明，RCM与AGCM在大尺度气候结构方面具有高度一致性，地势高度、温度和风场均无显著趋势或偏差，证明该RCM在区域气候降尺度应用中具有可靠的动态一致性。

ABSTRACT

The regional climate model prepared from Eta WS forecast model has been integrated over South America with the horizontal resolution of 40 km for the period of 1960-1990. The model was forced at its lateral boundaries by the outputs of HadAM3P. The data of HadAM3P represent simulation of modern climate with the resolution about 150 km. In order to prepare climate regional model from the Eta forecast model multiple modifications and corrections were made in the original model. The run of climate Eta model was made on the supercomputer SX-6. The detailed analysis of the results of dynamical downscaling experiment includes an investigation of a consistency between the regional and AGCM models as well as of ability of the regional model to resolve important features of climate fields on the finer scale than that resolved by AGCM. In this work the results of the investigation of a consistency between the output fields of the Eta model and HadAM3P are presented. The geopotential, temperature and wind fields of both models were analysed. For the evaluation of the likeness of these two models outputs,there were used Fourier analysis of time series, consistency index, constituted from linear regression coefficients, time mean and space mean models' arithmetic difference and root mean square difference, dispersion analysis,and some others characteristics. This investigation demonstrates that there are not significant differences in behaviour and spatial arragement of large-scale structures of the two models. Also, the regional model characteristics do not have considerable positive or negative trend during integration time in relation to the global model characteristics. From the total analysis we can affirm that in the description of large-scale climate structures these two models are in consistency.

研究动机与目标

• 评估基于Eta数值天气预报模型的区域气候模型（RCM）与驱动其运行的大气通用气候模型（HadAM3P）在南美洲的动态一致性。
• 评估RCM是否在空间分辨率提升的情况下，保留了与分辨率较低的AGCM相比更精细的大尺度气候特征。
• 确定RCM在30年模拟期间是否引入了显著的偏差或趋势。
• 通过对比关键大气场，验证RCM在区域气候降尺度应用中的可靠性。

提出的方法

• 将Eta区域模型从数值天气预报模型改编而来，经过多项修改与校正，以适用于气候模拟。
• 利用HadAM3P（150公里分辨率）提供的侧边界条件，将模型在南美洲区域以40公里水平分辨率从1960年积分至1990年。
• 采用傅里叶分析、线性回归系数、时间与空间平均差值、均方根差值以及离散度分析等方法，对比模型输出场。
• 分析了RCM与AGCM在位势高度、温度和风场方面的时间与空间一致性。
• 基于回归系数构建一致性指数，以量化两模型在时间行为上的相似性。
• 统计比较包括RCM与AGCM输出之间的算术差值、均方根差值以及方差分析。

实验结果

研究问题

• RQ1 基于Eta的RCM与HadAM3P AGCM在位势高度、温度和风场的大尺度大气结构方面的一致性如何？
• RQ2 在1960–1990年期间，RCM的输出相对于AGCM是否表现出显著的正向或负向趋势？
• RQ3 RCM在不引入系统性偏差的前提下，其分辨率提升是否能更精细地解析气候特征，优于分辨率较低的AGCM？
• RQ4 RCM输出的时间与空间模式在统计上是否与驱动其运行的AGCM一致？

主要发现

• Eta RCM与HadAM3P在大尺度气候结构的行为特征与空间分布上无显著差异。
• 在30年模拟期间，RCM的输出场相对于AGCM未表现出显著的正向或负向趋势。
• 基于线性回归系数构建的一致性指数，证实了两模型之间具有高度的时间相似性。
• 时间平均值与空间平均值的算术差值，以及均方根差值，表明两模型之间系统性偏差极小。
• 离散度分析表明，RCM中的变异性模式与AGCM一致。
• 总体而言，两模型在大尺度气候特征上表现出高度的动态一致性，验证了RCM在区域气候降尺度应用中的可靠性。