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Idealized single-forcing GCM simulations with GFDL CM2.1

Erb, Michael; Broccoli, Anthony; Raney, Bryan

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  "publisher": "Zenodo", 
  "DOI": "10.5281/zenodo.1194480", 
  "language": "eng", 
  "title": "Idealized single-forcing GCM simulations with GFDL CM2.1", 
  "issued": {
    "date-parts": [
  "abstract": "<p>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).&nbsp; 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.&nbsp; 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 CO<sub>2</sub>, and LGM-sized ice sheets.&nbsp; The values chosen for the orbital simulations represent the extreme values of the past 900 thousand years.</p>\n\n<p>Simulations were run for at least 500 years, and forcings do not change from year to year.&nbsp; The uploaded files are 100 year annual-means and monthly climatologies.&nbsp; Variables are presented for the atmosphere, ocean, sea ice, and land.&nbsp; Monthly ocean files are not currently available; please contact Michael Erb at if you are interested in those results.</p>\n\n<p>&nbsp;</p>\n\n<p>=== FORCINGS ===</p>\n\n<p>Preindustrial climate forcings were set to the following values:</p>\n\n<p>&nbsp;- Obliquity: 23.439&deg;</p>\n\n<p>&nbsp;- Longitude of perihelion: 102.93&deg;</p>\n\n<p>&nbsp;- Eccentricity: 0.0167</p>\n\n<p>&nbsp;- CO<sub>2</sub>: 286 ppm</p>\n\n<p>&nbsp;- Ice sheets: 0 ka BP</p>\n\n<p>The remaining simulations explore the climate response to a change in one of these forcings, with all other forcings set to preindustrial levels.&nbsp; Forcings are specified as follows:</p>\n\n<p>&nbsp;- lo_obliq and hi_obliq: Obliquity is set to 22.079&deg; or 24.480&deg;, respectively.</p>\n\n<p>&nbsp;- 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.&nbsp; This corresponds to a longitude of perihelion of 0&deg;, 90&deg;, 180&deg;, or 270&deg;, respectively.</p>\n\n<p>&nbsp;- ECC_0: Eccentricity is set to 0.</p>\n\n<p>&nbsp;- half_CO2: CO<sub>2</sub> is set to 143 ppm.</p>\n\n<p>&nbsp;- ice_sheets: Ice sheets and sea level are set to Last Glacial Maximum (LGM) levels.&nbsp; Ice sheets come from the ICE-5G reconstruction.</p>\n\n<p>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.&nbsp; 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:</p>\n\n<p>- preind_exp1: Control simulation for obliquity simulations.</p>\n\n<p>- preind_exp2: Control simulation for precession, eccentricity, and half CO<sub>2</sub> simulations.</p>\n\n<p>- preind_exp3: Control simulation for ice sheets simulation.</p>\n\n<p>&nbsp;</p>\n\n<p>=== NOTES ===</p>\n\n<p>More detailed description of these simulations, as well as results, can be found in the following papers:</p>\n\n<p>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.</p>\n\n<p>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.</p>\n\n<p>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.</p>\n\n<p>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.</p>\n\n<p>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.</p>\n\n<p>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>.</p>\n\n<p>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></p>\n\n<p>Note that the monthly data analyzed in some of these papers has been converted to a common fixed-angular calendar in which every &quot;month&quot; corresponds to a 30&deg; arc of Earth&#39;s orbit.&nbsp; This was done because changes in precession affect the speed at which Earth travels through different parts of its orbit according to Kepler&#39;s second law, complicating the comparison of months in different precession experiments.&nbsp; However, the results provided in this repository use the model&#39;s original fixed-day calendar.</p>\n\n<p>The half_CO2, ice_sheets, and preind_exp3 simulations were run by Bryan Raney (; Most of the remaining experiments were run by Michael Erb.&nbsp; If you use these simulations for research, please let us know.</p>\n\n<p>For a similar set of experiments using another model (NCAR CESM), see doi:10.5281/zenodo.1194490.</p>\n\n<p>Contact:<br>\nMichael Erb<br>\nPostdoctoral Scholar at Northern Arizona University<br>\</p>", 
  "author": [
      "family": "Erb, Michael"
      "family": "Broccoli, Anthony"
      "family": "Raney, Bryan"
  "version": "1.0.0", 
  "type": "dataset", 
  "id": "1194480"
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