Solar forcing for CMIP6 (v3.2)
Solar forcing for CMIP6 (v3.2)
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DOI：
10.5194/gmd-10-2247-2017
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发表时间：
2017-06-22
影响因子：
5.1
通讯作者：
Versick, Stefan
中科院分区：
文献类型：
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作者：
Matthes, Katja;Funke, Bernd;Versick, Stefan
本文描述了CMIP 6的推荐太阳强迫数据集，并重点介绍了相对于CMIP 5的变化。太阳强迫提供了辐射特性，即太阳总辐照度（TSI），太阳光谱辐照度（SSI）和F10.7指数以及粒子强迫，包括地磁指数Ap和Kp，电离率，以解释太阳质子，电子和银河宇宙射线的影响。这是第一次为CMIP演习提供太阳驱动粒子强迫的建议。太阳强迫数据集分别以每日和每月分辨率提供，用于CMIP 6工业化前控制，历史（1850-2014）和未来（2015-2300）模拟。对于工业化前的控制模拟，提供了恒定和随时间变化的太阳强迫分量，后者包括11年和更短的时间尺度上的变化，但没有长期的变化。对于未来，我们提供了一个现实的情况下，太阳的行为可能是什么，以及一个额外的极端蒙德最低限度的敏感性的情况。在历史模拟中，TSI和SSI时间序列被定义为适应CMIP 6需求的两个太阳辐照度模式的平均值：经验模式（NRLTSI 2-NRLSSI 2）和半经验模式（SATIRE）。推荐一个新的更低的TSI值：当代太阳周期平均值现在是1361.0 W m（-2）。在CMIP 6数据集中，TSI在最近三个太阳活动周期中有轻微的负趋势，导致全球辐射强迫只有-0.04 W m（-2）。在200-400 nm的波长范围内，这是重要的臭氧光化学，CMIP 6太阳强迫数据集显示了更大的太阳周期变率的贡献比CMIP 5（50%比35%）。我们比较了CMIP 6太阳强迫数据集的气候效应，其CMIP 5的前身，通过使用两个化学气候模式和参考辐射传输模式的时间切片实验。CMIP 6数据集与CMIP 5数据集长期平均SSI的差异对气候平流层条件的影响（平流层顶短波加热率较低，为-0.35 K天（-1）），平流层温度较低（平流层上部为-1.5K），平流层下部臭氧丰度较低（3%），臭氧丰度较高（平流层上部和中间层下部为+1.5%）。在11年太阳周期的最大和最小阶段之间，使用CMIP 6强迫数据集，热带平流层上层的短波加热率（平流层顶+0.2 K天（-1）），温度（类似于平流层顶的1 K）和臭氧（平流层上层+2.5%）增加。这种太阳周期响应略大，但与CMIP 5强迫模式相比，在统计上没有显著差异。鼓励具有良好分辨率的短波辐射方案的CMIP 6模式规定SSI变化，并包括太阳引起的平流层臭氧变化，以便与仅规定TSI和/或排除太阳臭氧响应的模式相比，更好地代表太阳气候变率。我们发现，每月平均太阳引起的臭氧变化隐含在CHINA/CCMI CMIP 6臭氧数据库的历史模拟，这是来自瞬态化学气候模式模拟，并已开发的气候模式，不计算臭氧交互。不含化学成分的CMIP 6模型在进行工业化前的控制模拟时，需要使用包括太阳变化的修正版的Ozone/CCMI臭氧数据库。还鼓励具有交互化学作用的CMIP 6模型使用粒子强迫数据集，这将首次解决粒子的潜在长期影响。粒子强迫的考虑已被证明可以显著改善极地中层大气中活性氮和臭氧变化的代表性，最终导致全球模型中太阳气候变化代表性的进一步改善。
This paper describes the recommended solar forcing dataset for CMIP6 and highlights changes with respect to CMIP5. The solar forcing is provided for radiative properties, namely total solar irradiance (TSI), solar spectral irradiance (SSI), and the F10.7 index as well as particle forcing, including geomagnetic indices Ap and Kp, and ionization rates to account for effects of solar protons, electrons, and galactic cosmic rays. This is the first time that a recommendation for solar-driven particle forcing has been provided for a CMIP exercise. The solar forcing datasets are provided at daily and monthly resolution separately for the CMIP6 preindustrial control, historical (1850-2014), and future (2015-2300) simulations. For the preindustrial control simulation, both constant and time-varying solar forcing components are provided, with the latter including variability on 11-year and shorter timescales but no long-term changes. For the future, we provide a realistic scenario of what solar behavior could be, as well as an additional extreme Maunder-minimum-like sensitivity scenario. This paper describes the forcing datasets and also provides detailed recommendations as to their implementation in current climate models.For the historical simulations, the TSI and SSI time series are defined as the average of two solar irradiance models that are adapted to CMIP6 needs: an empirical one (NRLTSI2-NRLSSI2) and a semi-empirical one (SATIRE). A new and lower TSI value is recommended: the contemporary solar-cycle average is now 1361.0 W m(-2). The slight negative trend in TSI over the three most recent solar cycles in the CMIP6 dataset leads to only a small global radiative forcing of -0.04 W m(-2). In the 200-400 nm wavelength range, which is important for ozone photochemistry, the CMIP6 solar forcing dataset shows a larger solar-cycle variability contribution to TSI than in CMIP5 (50% compared to 35 %).We compare the climatic effects of the CMIP6 solar forcing dataset to its CMIP5 predecessor by using time-slice experiments of two chemistry-climate models and a reference radiative transfer model. The differences in the long-term mean SSI in the CMIP6 dataset, compared to CMIP5, impact on climatological stratospheric conditions (lower shortwave heating rates of -0.35 K day(-1) at the stratopause), cooler stratospheric temperatures (-1.5K in the upper stratosphere), lower ozone abundances in the lower stratosphere (3 %), and higher ozone abundances (+1.5% in the upper stratosphere and lower mesosphere). Between the maximum and minimum phases of the 11-year solar cycle, there is an increase in shortwave heating rates (+0.2 K day(-1) at the stratopause), temperatures (similar to 1 K at the stratopause), and ozone (+2.5% in the upper stratosphere) in the tropical upper stratosphere using the CMIP6 forcing dataset. This solar-cycle response is slightly larger, but not statistically significantly different from that for the CMIP5 forcing dataset.CMIP6 models with a well-resolved shortwave radiation scheme are encouraged to prescribe SSI changes and include solar-induced stratospheric ozone variations, in order to better represent solar climate variability compared to models that only prescribe TSI and/or exclude the solar-ozone response. We show that monthly-mean solar-induced ozone variations are implicitly included in the SPARC/CCMI CMIP6 Ozone Database for historical simulations, which is derived from transient chemistry-climate model simulations and has been developed for climate models that do not calculate ozone interactively. CMIP6 models without chemistry that perform a preindustrial control simulation with time-varying solar forcing will need to use a modified version of the SPARC/CCMI Ozone Database that includes solar variability. CMIP6 models with interactive chemistry are also encouraged to use the particle forcing datasets, which will allow the potential long-term effects of particles to be addressed for the first time. The consideration of particle forcing has been shown to significantly improve the representation of reactive nitrogen and ozone variability in the polar middle atmosphere, eventually resulting in further improvements in the representation of solar climate variability in global models.