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pmip3:wg:p2k:meetings [2014/05/15 15:30]
jungclaus [Splinter meeting at the EGU 2013]
pmip3:wg:p2k:meetings [2014/06/23 12:07]
jungclaus [Meetings]
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 ===== Meetings ===== ===== Meetings =====
 +Minutes regarding Last Millennium / Past2k simulations from the PMIP conference Namur May 2014
 +Last Millennium (PMIP: past1000) simulations have been a very successful contribution to CMIP5.
 +11 groups provided one or more realizations for the standard past1000 period 850-1849, applying various choices of forcing boundary conditions. For most simulations matching historical simulations are available. Some groups did multiple realizations with different choices for forcing or single-forcing experiments. Ensemble simulations appear to be particular useful since the signal-to-noise ratio is usually small.
 +Last Millennium simulations from PMIP3 as well as pre-PMIP3 exercises were quite prominent in IPCC AR5; not only in chapter 5 (Information from Paleo Archives), but also in chapter 9 (Evaluation of climate models). Emerging achievements obtained in the past1000 context are:
 +Simulations of the late Holocene ​
 +• serve to put in perspective recent anthropogenic changes with variability due to natural forcing or internal variations
 +• Allow analyzing response to forcing under different boundary conditions
 +• Allow in-depth comparison with the most reliable and diverse collection of paleo-proxies,​ on global, regional and local scale
 +Past2k and PAGES2K
 +The link between past1000 simulations and the reconstruction community (identified 2012 at the Crewe meeting) has been established successfully. The PAGES/​Past2K Madrid workshop was quite instrumental and many analyses projects and a synthesis-paper are underway. Some of the resources obtained within these efforts should be transferred to the Past2K wiki page.
 +Lessons learned from PMIP3/CMIP5
 +There is need to make sure that there are continuous simulations from the pre-industrial millennium through the historical period to present. It was difficult to find the “historical” CMIP5 simulations fitting to the past1000 simulations.
 +Regarding the question if one should include the first millennium in future late Holocene transient simulations (0-2010 CE) was discussed controversial. Most of the modellers felt that the first millennium with its uncertain forcing history and probably weak forcing from volcanoes would not add much information. Moreover, the uncertainty in reconstructions is high before 1200 CE. CPU-time might be better spent for ensemble/​multiple realizations of the last millennium.
 +Forcing choices should be reviewed for an upcoming past1000 exercise. New reconstructions of volcanoes are underway. There is no convergence/​consensus on the amplitude of solar forcing.
 +Although there was some critique on the “freedom of choice” for the forcing boundary conditions (i.e. that there was no recommended “standard” past1000 protocol that every group had to follow), the group felt that flexibility in forcing BCs is OK as long it is ensured that the parameter/​BC space was well sampled. In the future this should probably happen in a more organized way. It  was also felt that a better documentation of the implementation of forcing BCs is needed as well as sensitivity studies. For volcanic aerosols, there is a VolcMip initiative emerging (D. Zanchettin and others), that would be very helpful.
 +PMIP experiments in CMIP(6)
 +It is not clear yet which paleo simulations will be recommended as part of CMIP6. The structure and nature of CMIP has changed and there will be many MIPs around a core of experiments,​ called “DECK”.
 +MIPs have a good chance to be endorsed that demonstrate to
 +• Follow a standard experiment design
 +• Get together a sufficient number of participating groups
 +• Make sure that all models have provided DECK experiments
 +• Ensure data availability
 + ​Priority will likely be given to projects that tackle the WCRP grand challenges:
 +Clouds, Cryosphere, Extremes, Regional Climate, sea-level rise, water availability
pmip3/wg/p2k/meetings.txt · Last modified: 2014/06/23 12:07 by jungclaus