Interannual variability and predictability in an ensemble of AMIP climate simulations conducted with the CCC GCM2
Interannual variability and predictability in an ensemble of AMIP climate simulations conducted with the CCC GCM2
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DOI：
10.1007/s003820050146
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发表时间：
1996-11
期刊：
影响因子：
4.6
通讯作者：
F. Zwiers
中科院分区：
文献类型：
--
作者：
F. Zwiers
本研究考虑了使用加拿大气候中心第二代大气环流模型 (CCC GCM2) 进行的六次 10 年气候模拟的集合。每个模拟都是根据大气模型比对项目 (AMIP) 实验协议进行的，使用基于 1979 年 1 月至 1988 年 12 月观测的月平均海面温度和海冰范围。其中一个模拟是在 CRAY 计算机上进行的，是从分析 1979 年 1 月 1 日的条件开始的，而其余 5 个模拟是在 NEC 计算机上进行的，是根据从长期控制集成获得的先前模拟模型状态开始的。使用方差统计分析技术将方差划分为多个分量，检查和比较模拟和观测的 500 hPa 位势、850 hPa 温度和 300 hPa 气流函数的年际变化和潜在可预测性。研究发现，AMIP 指定的边界条件会在热带地区以及在较小程度上在温带纬度地区的年际时间尺度上引起统计上显着的可预测方差。此外，大气和地表之间的局部相互作用显然会在热带低层大气以及温带低层大气的某些位置引起大量潜在的可预测的年际变化。没有证据表明大气的内部动力学本身会在年际时间尺度上产生潜在的可预测的变化。我们能够检测所使用的两台计算机上模拟的气候之间的差异，这一事实证明了所使用的统计方法的敏感性。追踪这些物理上微不足道的变化的原因。通过确认初始条件的选择不会导致显着的模拟间变化来检查统计程序。这些模拟也被解释为气候预测的整体，其预测能力仅依赖于指定的边界条件。这些预测是根据观察结果和预测本身进行验证的。与其他研究一致，我们发现热带地区的预报技巧非常高，温带地区的预报技巧中等。
This study considers an ensemble of six 10-year climate simulations conducted with the Canadian Climate Centre 2nd generation General Circulation Model (CCC GCM2). Each simulation was forced according to the Atmospheric Model Intercomparison Project (AMIP) experimental protocol using monthly mean sea surface temperatures and sea-ice extents based on observations for January, 1979 to December 1988. One simulation, conducted on a CRAY computer, was initiated from analysed 1 January 1979 conditions while the remaining 5 simulations, conducted on a NEC computer, were initiated from previously simulated model states obtained from a long control integration. The interannual variability and potential predictability of simulated and observed 500 hPa geopotential, 850 hPa temperature and 300 hPa stream function are examined and inter-compared using statistical analysis of variance techniques to partition variance into a number of components. The boundary conditions specified by AMIP are found to induce statistically significant amounts of predictable variance on the interannual time scale in the tropics and, to a lesser extent, at extratropical latitudes. In addition, local interactions between the atmosphere and the land surface apparently induce significant amounts of potentially predictable interannual variance in the tropical lower atmosphere and also at some locations in the temperate lower atmosphere. No evidence was found that the atmosphere's internal dynamics on their own generate potentially predictable variations on the interannual time scale. The sensitivity of the statistical methods used is demonstrated by the fact that we are able to detect differences between the climates simulated on the two computers used. The causes of these physically insignificant changes are traced. The statistical procedures are checked by confirming that the choice of initial conditions does not lead to significant inter-simulation variation. The simulations are also interpreted as an ensemble of climate forecasts that rely only on the specified boundary conditions for their predictive skill. The forecasts are verified against observations and against themselves. In agreement with other studies it was found that the forecasts have very high skill in the tropics and moderate skill in the extratropics.