Idealized Single-Forcing Gcm Simulations With Gfdl Cm2.1

This repository contains a set of single-forcing general circulation model (GCM) simulations run with the Geophysical Fluid Dynamics Laboratory (GFDL) Climate Model 2.1 (CM2.1). In each of these equilibrium simulations, one climate forcing was altered while all others were held constant at preindustrial levels, modeling the climate response to individual climate forcings. Simulations were run for obliquity (low and high obliquity), precession (four phases of the precession cycle with high eccentricity, and one simulation with eccentricity set to zero), half CO₂, and LGM-sized ice sheets. The values chosen for the orbital simulations represent the extreme values of the past 900 thousand years. Simulations were run for at least 500 years, and forcings do not change from year to year. The uploaded files are 100 year annual-means and monthly climatologies. Variables are presented for the atmosphere, ocean, sea ice, and land. Monthly ocean files are not currently available; please contact Michael Erb at [e-mail] if you are interested in those results. === FORCINGS === Preindustrial climate forcings were set to the following values: - Obliquity: 23.439° - Longitude of perihelion: 102.93° - Eccentricity: 0.0167 - CO₂: 286 ppm - Ice sheets: 0 ka BP The remaining simulations explore the climate response to a change in one of these forcings, with all other forcings set to preindustrial levels. Forcings are specified as follows: - lo_obliq and hi_obliq: Obliquity is set to 22.079° or 24.480°, respectively. - 0_AEQ, 90_WSOL, 180_VEQ, and 270_SSOL: Perihelion occurs at the NH autumnal equinox, winter solstice, vernal equinox, or summer solstice, respectively, with eccentricity set to 0.0493. This corresponds to a longitude of perihelion of 0°, 90°, 180°, or 270°, respectively. - ECC_0: Eccentricity is set to 0. - half_CO2: CO₂ is set to 143 ppm. - ice_sheets: Ice sheets and sea level are set to Last Glacial Maximum (LGM) levels. Ice sheets come from the ICE-5G reconstruction. A note about preindustrial simulations: The single-forcing simulations were not all run at the same time, and some details of the model or setup changed. Because of this, if a preindustrial control simulation is wanted for analysis, it is recommended that you use certain preindustrial simulations for certain comparisons, as follows: - preind_exp1: Control simulation for obliquity simulations. - preind_exp2: Control simulation for precession, eccentricity, and half CO₂ simulations. - preind_exp3: Control simulation for ice sheets simulation. === NOTES === More detailed description of these simulations, as well as results, can be found in the following papers: Mantsis, D. F., A. C. Clement, A. J. Broccoli, and M. P. Erb, 2011: Climate feedbacks in response to changes in obliquity. <em>J. Climate</em>, <strong>24</strong>, 2830-2845, doi:10.1175/2010CJLI3986.1. Erb, M. P., A. J. Broccoli, and A. C. Clement, 2013: The contribution of radiative feedbacks to obliquity driven climate change. <em>J. Climate</em>, <strong>26</strong>, 5897-5914, doi:10.1175/JCLI-D-12-00419.1. Mantsis, D. F., B. R. Lintner, A. J. Broccoli, M. P. Erb, A. C. Clement, and H.-S. Park, 2014: The response of large-scale circulation to obliquity-induced changes in meridional heating gradients. <em>J. Climate</em>, <strong>27</strong>, 5504-5516, doi:10.1175/JCLI-D-13-00526.1. Erb, M. P., A. J. Broccoli, N. T. Graham, A. C. Clement, A. T. Wittenberg, and G. A. Vecchi, 2015: Response of the equatorial Pacific seasonal cycle to orbital forcing. <em>J. Climate</em>, <strong>28</strong>, 9258-9276, doi:10.1175/JCLI-D-15-0242.1. Erb, M. P., C. S. Jackson, and A. J. Broccoli, 2015: Using single-forcing GCM simulations to reconstruct and interpret Quaternary climate change. <em>J. Climate</em>, <strong>28</strong>, 9746-9767, doi:10.1175/JCLI-D-15-0329.1. Erb, M. P., C. S. Jackson, A. J. Broccoli, D. W. Lea, P. J. Valdes, M. Crucifix, and P. N. DiNezio, in press: Model evidence for a seasonal bias in Antarctic ice cores. <em>Nature Communications</em>. Bosmans, J. H. C., M. P. Erb, A. M. Dolan, S. S. Drijfhout, E. Tuenter, F. J. Hilgen, D. Edge, J. O. Pope, and L. J. Lourens, in press: Response of the Asian summer monsoons to idealized precession and obliquity forcing in a set of GCMs. <em>Quat. Sci. Rev.</em> Note that the monthly data analyzed in some of these papers has been converted to a common fixed-angular calendar in which every "month" corresponds to a 30° arc of Earth's orbit. This was done because changes in precession affect the speed at which Earth travels through different parts of its orbit according to Kepler's second law, complicating the comparison of months in different precession experiments. However, the results provided in this repository use the model's original fixed-day calendar. The half_CO2, ice_sheets, and preind_exp3 simulations were run by Bryan Raney ([e-mail]). Most of the remaining experiments were run by Michael Erb. If you use these simulations for research, please let us know. For a similar set of experiments using another model (NCAR CESM), see doi:10.5281/zenodo.1194490. Contact:<br> Michael Erb<br> Postdoctoral Scholar at Northern Arizona University<br> [e-mail]本数据集仓库包含一组采用地球物理流体动力学实验室（Geophysical Fluid Dynamics Laboratory，GFDL）气候模式2.1（CM2.1）开展的单强迫通用环流模式（General Circulation Model，GCM）模拟实验。在每一组平衡态模拟实验中，仅改变单一气候强迫因子，其余所有强迫因子均维持在工业化前水平，以此模拟单个气候强迫因子引发的气候响应。模拟实验涵盖黄赤交角（低、高两种黄赤交角工况）、岁差（高偏心率下岁差周期的4个相位，以及偏心率设为0的1组实验）、CO₂减半以及末次盛冰期（Last Glacial Maximum，LGM）规模冰盖工况。轨道模拟所采用的强迫参数值，均为过去90万年中的极端取值。 所有模拟实验均至少运行500年，且强迫因子不随年份变化。本次上传的文件为100年的年平均与月平均气候态数据，涵盖大气、海洋、海冰与陆面各变量。目前暂未提供逐月海洋数据文件，若您需要获取相关结果，请联系Michael Erb，邮箱为[e-mail]。 === 强迫因子设置 === 工业化前气候强迫因子设置如下： - 黄赤交角：23.439° - 近日点经度：102.93° - 偏心率：0.0167 - CO₂：286 ppm - 冰盖：0千年前（ka BP） 其余模拟实验则仅改变上述某一项强迫因子，其余强迫因子均维持工业化前水平，各强迫工况的具体设置如下： - lo_obliq与hi_obliq：分别将黄赤交角设为22.079°与24.480°。 - 0_AEQ、90_WSOL、180_VEQ与270_SSOL：分别设置近日点出现在北半球秋分、冬至、春分与夏至时刻，偏心率设为0.0493，对应近日点经度分别为0°、90°、180°与270°。 - ECC_0：将偏心率设为0。 - half_CO2：将CO₂浓度设为143 ppm。 - ice_sheets：将冰盖与海平面设置为末次盛冰期（LGM）水平，冰盖数据来自ICE-5G重建方案。 === 工业化前对照模拟说明 === 本次单强迫模拟实验并非同期开展，模式或实验设置的部分细节存在差异。因此，若需使用工业化前对照模拟开展分析，建议针对不同对比需求选用对应工况的对照模拟，具体如下： - preind_exp1：黄赤交角类模拟实验的对照模拟。 - preind_exp2：岁差、偏心率与CO₂减半类模拟实验的对照模拟。 - preind_exp3：冰盖类模拟实验的对照模拟。 === 补充说明 === 关于本系列模拟实验与相关研究结果的详细描述，请参阅以下文献： Mantsis, D. F., A. C. Clement, A. J. Broccoli, and M. P. Erb, 2011: Climate feedbacks in response to changes in obliquity. *J. Climate*, **24**, 2830-2845, doi:10.1175/2010CJLI3986.1. Erb, M. P., A. J. Broccoli, and A. C. Clement, 2013: The contribution of radiative feedbacks to obliquity driven climate change. *J. Climate*, **26**, 5897-5914, doi:10.1175/JCLI-D-12-00419.1. Mantsis, D. F., B. R. Lintner, A. J. Broccoli, M. P. Erb, A. C. Clement, and H.-S. Park, 2014: The response of large-scale circulation to obliquity-induced changes in meridional heating gradients. *J. Climate*, **27**, 5504-5516, doi:10.1175/JCLI-D-13-00526.1. Erb, M. P., A. J. Broccoli, N. T. Graham, A. C. Clement, A. T. Wittenberg, and G. A. Vecchi, 2015: Response of the equatorial Pacific seasonal cycle to orbital forcing. *J. Climate*, **28**, 9258-9276, doi:10.1175/JCLI-D-15-0242.1. Erb, M. P., C. S. Jackson, and A. J. Broccoli, 2015: Using single-forcing GCM simulations to reconstruct and interpret Quaternary climate change. *J. Climate*, **28**, 9746-9767, doi:10.1175/JCLI-D-15-0329.1. Erb, M. P., C. S. Jackson, A. J. Broccoli, D. W. Lea, P. J. Valdes, M. Crucifix, and P. N. DiNezio, in press: Model evidence for a seasonal bias in Antarctic ice cores. *Nature Communications*. Bosmans, J. H. C., M. P. Erb, A. M. Dolan, S. S. Drijfhout, E. Tuenter, F. J. Hilgen, D. Edge, J. O. Pope, and L. J. Lourens, in press: Response of the Asian summer monsoons to idealized precession and obliquity forcing in a set of GCMs. *Quat. Sci. Rev.*. 需注意的是，部分文献中所分析的逐月数据已被转换为统一的固定角历法，其中每一个“月”对应地球轨道上30°的弧段。这一处理是因为岁差变化会根据开普勒第二定律改变地球在轨道不同区段的运行速度，导致不同岁差实验间的月份对比变得复杂。但本仓库提供的模拟结果仍采用模式原始的固定日历法。 half_CO2、ice_sheets与preind_exp3三组模拟实验由Bryan Raney（邮箱：[e-mail]）完成，其余多数实验由Michael Erb完成。若您将本数据集用于研究工作，请告知我们。 若需获取采用美国国家大气研究中心社区地球系统模型（NCAR CESM）开展的同类实验数据集，请参阅doi:10.5281/zenodo.1194490。 联系方式：<br> Michael Erb<br> 北亚利桑那大学博士后研究员<br> [e-mail]