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 for most of the simulations are not currently available; please contact Michael Erb at [e-mail] if you are interested in those results. === UPDATES === v1.1.0: Monthly ocean files have been added for the obliquity simulations. === 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. 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. 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:Michael ErbAssistant Research Professor at Northern Arizona [e-mail]本数据集包含一系列单强迫通用循环模式（General Circulation Model, GCM）模拟结果，由地球物理流体动力学实验室（Geophysical Fluid Dynamics Laboratory, GFDL）的气候模型2.1（Climate Model 2.1, CM2.1）运行生成。在所有平衡态模拟中，仅改变单一气候强迫项，其余强迫项均维持在工业化前水平，以此模拟单个气候强迫引发的气候响应。本次模拟涵盖黄赤交角（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组模拟）、CO₂减半以及末次冰盛期（Last Glacial Maximum, LGM）规模冰盖的强迫场景。轨道模拟所选用的参数值，对应过去90万年以来的极端轨道参数。 所有模拟均至少运行500年，且强迫项不随年份变化。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、海冰与陆面变量。目前多数模拟的逐月海洋数据暂未开放，若需获取此类结果，请联系Michael Erb，邮箱：[e-mail]。 === 更新记录 === v1.1.0：新增黄赤交角模拟的逐月海洋数据文件。 === 强迫参数设定 === 工业化前气候强迫参数设置如下： - 黄赤交角：23.439° - 近日点经度：102.93° - 偏心率：0.0167 - CO₂浓度：286 ppm - 冰盖规模：0 ka BP（距今千年） 其余模拟均仅改变上述某一项强迫参数，其余参数维持工业化前水平。各强迫场景的具体设定如下： - 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（Northern Hemisphere, NH）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冰盛期（Last Glacial Maximum, LGM）水平，冰盖数据源自ICE-5G重建方案。 关于工业化前对照模拟的说明：本系列单强迫模拟并非同时开展，模型与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，建议针对不同对比场景选用对应的对照模拟： - preind_exp1：黄赤交角模拟的对照模拟。 - preind_exp2：岁差、偏心率与CO₂减半模拟的对照模拟。 - preind_exp3：冰盖模拟的对照模拟。 === 补充说明 === 本系列模拟的详细说明与相关研究结果可参考以下文献： 1. Mantsis, D. F.、A. C. Clement、A. J. Broccoli与M. P. Erb, 2011：黄赤交角变化引发的气候反馈。《气候学报》（J. Climate），24卷，2830-2845页，doi:10.1175/2010CJLI3986.1。 2. Erb, M. P.、A. J. Broccoli与A. C. Clement, 2013：辐射反馈对黄赤交角驱动气候变化的贡献。《气候学报》（J. Climate），26卷，5897-5914页，doi:10.1175/JCLI-D-12-00419.1。 3. Mantsis, D. F.、B. R. Lintner、A. J. Broccoli、M. P. Erb、A. C. Clement与H.-S. Park, 2014：大尺度环流对黄赤交角引发的经向加热梯度变化的响应。《气候学报》（J. Climate），27卷，5504-5516页，doi:10.1175/JCLI-D-13-00526.1。 4. Erb, M. P.、A. J. Broccoli、N. T. Graham、A. C. Clement、A. T. Wittenberg与G. A. Vecchi, 2015：赤道太平洋季节循环对轨道强迫的响应。《气候学报》（J. Climate），28卷，9258-9276页，doi:10.1175/JCLI-D-15-0242.1。 5. Erb, M. P.、C. S. Jackson与A. J. Broccoli, 2015：利用单强迫GCM模拟重建与解释第四纪气候变化。《气候学报》（J. Climate），28卷，9746-9767页，doi:10.1175/JCLI-D-15-0329.1。 6. Erb, M. P.、C. S. Jackson、A. J. Broccoli、D. W. Lea、P. J. Valdes、M. Crucifix与P. N. DiNezio, 已接收待刊：南极冰芯季节偏差的模式证据。《自然-通讯》（Nature Communications）。 7. Bosmans, J. H. C.、M. P. Erb、A. M. Dolan、S. S. Drijfhout、E. Tuenter、F. J. Hilgen、D. Edge、J. O. Pope与L. J. Lourens, 已接收待刊：多GCM框架下亚洲夏季风对理想岁差与黄赤交角强迫的响应。《第四纪科学评论》（Quat. Sci. Rev.）。 需注意：部分文献中所分析的逐月数据，已被转换为统一的固定角度历法，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，使得不同岁差实验中的月份对比变得复杂。但本数据集提供的结果仍采用模型原始的固定日期历法。 half_CO2、ice_sheets与preind_exp3模拟由Bryan Raney（邮箱：[e-mail]）完成，其余多数实验由Michael Erb完成。若您使用本数据集开展研究，请告知我们。 若需使用美国国家大气研究中心社区地球系统模型（National Center for Atmospheric Research Community Earth System Model, NCAR CESM）开展的同类实验数据集，请参考doi:10.5281/zenodo.1194490。 联系方式： Michael Erb 北亚利桑那大学助理研究教授 邮箱：[e-mail]