CMIP5 monthly data on single levels

This catalogue entry provides monthly climate projections on single levels from a large number of experiments, models, members and time periods computed in the framework of fifth phase of the Coupled Model Intercomparison Project (CMIP5). The term "single levels" is used to express that the variables are computed at one vertical level which can be surface (or a level close to the surface) or a dedicated pressure level in the atmosphere. Multiple vertical levels are excluded from this catalogue entry.
CMIP5 data are used extensively in the Intergovernmental Panel on Climate Change Assessment Reports (the latest one is IPCC AR5, which was published in 2014). The use of these data is mostly aimed at:

addressing outstanding scientific questions that arose as part of the IPCC reporting process;
improving the understanding of the climate system;
providing estimates of future climate change and related uncertainties;
providing input data for the adaptation to the climate change;
examining climate predictability and exploring the ability of models to predict climate on decadal time scales;
evaluating how realistic the different models are in simulating the recent past.

The term "experiments" refers to the three main categories of CMIP5 simulations:

Historical experiments which cover the period where modern climate observations exist. These experiments show how the GCMs performs for the past climate and can be used as a reference period for comparison with scenario runs for the future. The period covered is typically 1850-2005.
Ensemble of experiments from the Atmospheric Model Intercomparison Project (AMIP), which prescribes the oceanic variables for all models and during all period of the experiment. This configuration removes the added complexity of ocean-atmosphere feedbacks in the climate system. The period covered is typically 1950-2005.
Ensemble of climate projection experiments following the Representative Concentration Pathways (RCP) 2.6, 4.5, 6.0 and 8.5. The RCP scenarios provide different pathways of the future climate forcing. The period covered is typically 2006-2100, some extended RCP experimental data is available from 2100-2300.

In CMIP5, the same experiments were run using different GCMs. In addition, for each model, the same experiment was repeatedly done using slightly different conditions (like initial conditions or different physical parameterisations for instance) producing in that way an ensemble of experiments closely related. Note that CMIP5 GCM data can be also used as lateral boundary conditions for Regional Climate Models (RCMs). RCMs are also available in the CDS (see CORDEX datasets).
The data are produced by the participating institutes of the CMIP5 project. The latest CMIP GCM experiments will form the CMIP6 dataset, which will be published in the CDS in a later stage.

本目录条目提供了在耦合模式比较计划第五阶段（CMIP5）框架下，由大量实验、模型、成员和时间周期计算得出的月度气候预测。术语“单层”用于表达变量是在单一垂直层上计算的，该层可以是地表（或接近地表的层）或大气中的专用压力层。本目录条目排除了多个垂直层。CMIP5数据在政府间气候变化专门委员会评估报告中得到广泛使用（最新的是2014年发布的IPCC AR5）。这些数据的使用主要旨在：解决作为IPCC报告过程一部分出现的未决科学问题；增进对气候系统的理解；提供未来气候变化及其相关不确定性的估计；为气候变化适应提供输入数据；考察气候可预测性并探索模型在预测十年时间尺度上的能力；评估不同模型在模拟近期历史时的现实性。术语“实验”指的是CMIP5模拟的三个主要类别：历史实验，涵盖现代气候观测存在的时期，这些实验显示了GCMs对过去气候的表现，并可作为与未来情景运行比较的参考时期，通常覆盖的时期是1850-2005年；大气模式比较计划（AMIP）实验集，为所有模型和实验的所有时期指定海洋变量，这种配置消除了气候系统中海洋-大气反馈的额外复杂性，通常覆盖的时期是1950-2005年；遵循代表性浓度路径（RCP）2.6、4.5、6.0和8.5的气候预测实验集。RCP情景提供了未来气候强化的不同途径，通常覆盖的时期是2006-2100年，部分扩展的RCP实验数据可提供至2100-2300年。在CMIP5中，使用不同的GCM进行了相同的实验，此外，对于每个模型，相同的实验在略微不同的条件下（如初始条件或不同的物理参数化等）反复进行，从而产生了一系列紧密相关的实验。请注意，CMIP5 GCM数据也可用作区域气候模型（RCMs）的侧边界条件。RCMs亦可在CDS中找到（参见CORDEX数据集）。数据由CMIP5项目的参与机构生成。最新的CMIP GCM实验将形成CMIP6数据集，该数据集将在稍后阶段在CDS中发布。