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====== Last Millennium Experimental Design ======

<note warning>**Page in progress**: this is not the final version!\\ \\ Use the [[index#page_bottom_tag|discussion]] panel at the end of the page for comments </note>

The basic principle is that we should strive to include all relevant transient forcings over this period if the functionality exists in the model, noting that conformability with the CMIP5 controls and 20th Century transient is crucial. 

===== Boundary conditions =====
==== Summary of Last Millennium boundary conditions ====

^      ^   PMIP3  ^  Alternative solution  ^
|  Orbital parameters  |  Annually varying (Table provided (for years 0-2100 CE/AD) if not internally calculated)   |  1850 values [ **ecc** = 0.01676 ] - [ **obl** = 23.459° ] - [ **peri-180°** = 100.327° ] or same as Pre-Ind CMIP5 control | 
|  Date of vernal equinox  |  Mar 21 hr 0  |  same as CMIP5 control |
|  Trace gases  |  Annually varying (850-1850) ([[index#reconstructed_evolution_of_trace_gases|Table provided]])  |  constant at CMIP5 control levels  [ **CO<sub>2</sub>** =  ppm ] - [ **CH<sub>4</sub>** =  ppb ] - [ **N<sub>2</sub>O** =  ppb ] - [ **CFC** =  ] - [ **O<sub>3</sub>** =  ]  | 
|  Volcanic Aerosols  |  Multiple reconstructions (of AOD, Effective Radius, Mass)  |   |
|  Solar irradiance  |  Multiple reconstructions (default TBD)  |    |
|   Ozone    |  solar related variations (parameterised as function of change in solar irradiance - Drew Shindell)  |  same as pre-Ind control  |
|  Aerosols  |  biomass burning changes????   |  same as pre-Ind control  |
|  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)   |  No change from Pre-Ind control  |
|  Ice sheets      |  No changes from Pre-Ind control  |    |
|  Topography and coastlines  |  No change from Pre-Ind control   |    |

Please use the [[index#page_bottom_tag|discussion]] panel to **comment** this table!


===== Initial conditions =====

===== Additional information =====

==== Total Solar Irradiance ====


The following figure (click to get the full-size image) has been provided by [[johann.jungclaus@zmaw.de|Johann Jungclaus]] (MPI-M Hamburg)

{{:pmip3:design:lm:xsolarpag.png?500|Click to get the full-size image}}

Time series of TSI (Wm-2) from 800AD to 2000. For the COSMOS (MPI-M)
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). 

Candidate reconstructions: Krivova, Steinhilber, new Bard?, (TBD)

==== Volcanic Forcings ====

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 ====

The evolution of CO<sub>2</sub>, CH<sub>2</sub>, N<sub>2</sub>O over past 2 millennia {{:pmip3:design:lm:ghg_lawdome_giss_merge_c5mip_24jul09.1-2000.txt|table}} has been provided by [[joos@climate.unibe.ch|Fortunat Joos]] (University of Bern). Methods and references are provided in the downloadable file.


==== Orbital forcing ====

The following orbital parameters parameters should be used, if they are not internally calculated.

Note: calculation from Berger (1978), annually varying.

=== Precomputed table ===

The {{:pmip3:design:lm:pmip3_lm_orbital_parameters.txt|parameters' table}} has been supplied by 
[[gschmidt@giss.nasa.gov|Gavin Schmidt]] (GISS).

=== Linear regressions ===

Over the period 0-2100 CE, the parameters are well approximated by the following linear regressions:

^  Parameter  ^  Linear approximation  ^
|  ECC  |  0.017475 - 0.000000382 * Year |
|  OBL  |  23.697   - 0.000128 * Year |
|  PERI-180  |  68.79   + 0.0170 * Year |


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