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--- pmip3:design:lm:index [2009/08/01 23:38] – gavin
+++ pmip3:design:lm:index [2009/12/23 14:40] – Closed the discussion jypeter
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 ~~ODT~~
-~~DISCUSSION~~
+~~DISCUSSION:closed~~
 <html><a name="page_top_tag">&nbsp</a></html>
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 ^      ^   PMIP3  ^  Alternative solution  ^
-|  Orbital parameters  |  Annually varying (850-1850) (Table provided if not internally calculated)|  1850 values or same as Pre-Ind CMIP5 control [ **ecc** =  ] - [ **obl** = ° ] - [ **peri-180°** = ° ]  |
+|  Orbital parameters  |  Annually varying\\ [[index#orbital_forcing|Table provided (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 |
+|  Date of vernal equinox  |  Mar 21 hr 0  |  same as CMIP5 control  |
-|  Trace gases  |  Annually varying (850-1850) (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>** =  ]  |
+|  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)  | |
+|  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 Shinedll)  | same as pre-Ind control  |
+|   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 |
+|  Aerosols  |  biomass burning changes????   |  same as pre-Ind control  |
-|  Vegetation      | Land use conversion (forests to C3/C4 crops) (Pongratz, 2008, Foley and Ramunkutty)   |  No change from 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  |
-|                  | available from WDCC-Hamburg (http://cera-www.dkrz.de/WDCC/ui/Entry.jsp?acronym=LAND_COV_scen_800_1699)   |   |
 |  Ice sheets      |  No changes from Pre-Ind control  |    |
-|  Topography and coastlines  | No change 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!
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 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 |