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--- pmip3:design:lm:final [2009/12/21 20:28]
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+++ pmip3:design:lm:final [2009/12/21 20:59]
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-//Go to =>// [ [[pmip3:design:pi:final|PI]] ] - [ [[pmip3:design:6k:final|6ka]] ] - [ [[pmip3:design:21ka:final|21ka]] ] - [ **LM** ]
+//Go to =>// [ [[pmip3:design:pi:final|PI]] ] - [ [[pmip3:design:6k:final|6ka]] ] - [ [[pmip3:design:21k:final|21ka]] ] - [ **LM** ]
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 |   Ozone    |  solar related variations (parameterised as function of change in solar irradiance - Drew Shindell)  |  same as in CMIP5 PI  |
 |  Aerosols  |  biomass burning changes????   |  same as in CMIP5 PI  |
-|  Vegetation      |  Land use conversion (forests to C3/C4 crops) (Pongratz, 2009, Foley and Ramunkutty)\\ Available from WDCC-Hamburg\\ (http://cera-www.dkrz.de/WDCC/ui/Entry.jsp?acronym=LAND_COV_scen_800_1699)   |  same as in CMIP5 PI  |
+|  Vegetation      |  Land use conversion (forests to C3/C4 crops) (Pongratz, 2009, Foley and Ramunkutty)\\ Provided below  |  same as in CMIP5 PI  |
 |  Ice sheets      |  No changes from Pre-Ind control  |    |
 |  Topography and coastlines  |  same as in CMIP5 PI   |    |
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-The following figure (click to get the full-size image) has been provided by [[johann.jungclaus@zmaw.de|Johann Jungclaus]] (MPI-M Hamburg)
+==== Volcanic Forcings ====
-{{:pmip3:design:lm:xsolarpag.png?500|Click to get the full-size image}}
+Two alternative data sets are provided below. It is up to the groups to choose the Gao-Robock-Amann or the Crowley reconstruction for their last millenium simulation.
-Time series of TSI (Wm-2) from 800AD to 2000. For the COSMOS (MPI-M)
+=== The Gao-Robock-Ammann data set ===
-Millennium simulations (black curve), a 11 year cycle was added for consistency over the
-entire period.
-Notes: We will impose an 11 year cycle on pre-sunspot reconstructions for consistency of the spectrum of natural variability. Additionally, we will give a spectral set of irradiance changes based on modern variability observed by satellite (Lean).
+Time series of global hemispheric total stratospheric sulphate injections from volcanic eruptions for the past 1500 years as well as estimates of stratospheric loading as a function of latitude, altitude, and month are available from
+[[http://climate.envsci.rutgers.edu/IVI2/|IVI2link]]
-Candidate reconstructions: Krivova, Steinhilber, new Bard?, (TBD)
+The data are derived from 54 ice core records, 32 from the Arctic, and 22 from Antarctica. It is based on the most comprehensive set of ice cores, an updated extraction record, updated ice core deposition to global stratospheric aerosol loading conversion factors, and an advanced spatial-temporal transport parameterization scheme (Gao et al., 2008)
-==== Volcanic Forcings ====
+The stratospheric aerosol loadings (in units of Tg) provided in the IVI2 data set may be converted into aerosol optical depth (AOD) by dividing the loadings by 150 Tg (Stothers, 1984). The AOD time series can then be used to calculate the corresponding radiative forcing (in units of Wm-2) by multiplying it by (-20) (Wigley et al., 2005). The conversion to AOD is valid for aerosols with effective radius in the visible spectral range.
+Further explanation is provided here : {{:pmip3:design:lm:ivi2aodtsiconversion.pdf|}}
+Gao, C., A. Robock, and C. Ammann: Volcanic forcing of climate over the last 1500 years: An improved ice-core based index for climate models. J. Geophys. Res., 113, D2311, doi:10.1029/2008JD010239 (2008).
+Stothers, R.B., The great Tambora eruptions in 1815 and its aftermath. Science, 224(4654), 1191-1198 (1984).
+Wigley, T.M.L., C.M. Ammann, B.D. santer, and S.C.B. Raper: Effect of climate sensitivity on the response of volcanic forcing. J. Geophys. Res., 110,D09107, doi:10.1029/2004JD005557
+=== The Crowley data set ===
+The volcanic forcing is calculated using time series of aerosol optical depth (AOD) at 0.55μm and of the effective radius (Reff) (Crowley et al., 2008). The time resolution of the series is ten days and the data are provided at four equal area latitude bands.
+AOD estimates are based on a correlation between sulphate in Antarctic ice cores and satellite data (Sato et al., 1993).
+Reff growth and decay is based on satellite observations of the Pinatubo eruption in 1991, with eruptions larger than that of Pinatubo (maximum is 0.15) being scaled by the theoretical calculations for very large eruptions (Pinto et al., 1989). In the model AOD is distributed between 20-86 hPa over three vertical levels, with a maximum at 50 hPa.
+Sensitivity experiments for the model response to the Pinatubo eruption yield an average global temperature change (0.4 K) comparable to observations. For the largest eruption of the last millennium, the 1258 AD eruption, a NH summer temperature anomaly over land of 1.2 K is found in agreement with reconstructions (Timmreck et al., 2009)
+Crowley, T. et al. Volcanism and the Little Ice Age. PAGES Newsletter, 16, 22-23 (2008).
+Sato, M., Hansen, J.E., McCormick, M.P. & Pollack, J.B. Stratospheric aerosol optical depths, 1850-1990. J. Geophys. Res., 98(D12), 22,987-22,994, doi:10.1029/93JD02553 (1993).
+Pinto, J.P., Turco, R.P., & Toon, O.B. Self-limiting physical and chemical effects in volcanic eruption clouds. J. Geophys. Res., 94(D8), 11,165-11,174, doi:10.1029/JD094iD08p11165 (1989).
+Timmreck, C. et al. Limited temperature response to the very large AD 1258 volcanic eruption. Geophys. Res. Lett., 36, L21708, doi:10.1029/2009GL040083 (2009).
-Issues: compatability of eff. rad, zonality, height distribution with modern satellite (Sato) data.
-Candidate datasets: Crowley, Ammann - differences in thresholds for significant eruptions, peak forcing etc. Need merged/consistent fields. (Ammann)
 ==== Reconstructed evolution of trace gases ====
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 The data set can be obtained from the World Data Center for Climate (doi:10.1594/WDCC/RECON_LAND_COVER_800-1992).
 Pongratz, J., Reick, C.H., Raddatz, T. & Claussen, M. A reconstruction of global agricultural areas and land cover for the last millennium. Global Biogeochem. Cycles, 22, GB3018, doi:10.1029/2007GB003153 (2008).
+To access the files, click here [[http://cera-www.dkrz.de/WDCC/ui/Entry.jsp?acronym=RECON_LAND_COVER_800-1992|RECON_LAND_COVER_800-1992]]
 ===== Initial conditions =====

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