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--- pmip3:cmip6:design:21k:index [2015/03/24 22:52] – masa
+++ pmip3:cmip6:design:21k:index [2025/05/15 17:51] (current) – jypeter
@@ Line 1: / Line 1: @@
-~~DISCUSSION~~
+~~DISCUSSION:closed~~
 ====== PMIP-CMIP6 Experimental Design Discussion: Last Glacial Maximum ======
+<note warning>The PMIP4 experimental design available on the PMIP3 wiki has been **superseded** by the experimental design detailed on the [[https://pmip4.lsce.ipsl.fr/doku.php/exp_design|PMIP4 web site]]</note>
 <note tip>\\ Please submit your comments in the Discussion section at the end of this page</note>
@@ Line 9: / Line 12: @@
 The reference experiment to which the lgm is compared to is the pre-industrial control, which is part of the DECK.
-The lgm experimental set-up foreseen for PMIP-CMIP5 is as follows (cf. PMIP3 web site, with some modifications):
+For the **LGM**, our proposed experimental set-up for PMIP-CMIP6 is based on the [[pmip3:design:21k:final|PMIP3-CMIP5 set-up]]:
-**Insolation** (quite similar to pre-industrial)
+===== Orbital parameters =====
-eccentricity = 0.018994
+**eccentricity** = 0.018994
-obliquity = 22.949°
+**obliquity** = 22.949°
-perihelion-180° = 114.42°
+**perihelion-180°** = 114.42°
-solar constant: same as PI
+**Date of vernal equinox** = March 21 at noon
-**Concentration of atmospheric trace gases:**
+**solar constant** = same as PI
-CO2 = 185 ppm
-CH4 = 350 ppb
+===== Concentration of atmospheric trace gases =====
-N2O = 200 ppb
+**CO<sub>2</sub>** = 185 ppm
-CFC = 0
+**CH<sub>4</sub>** = 350 ppb
-O3 = same as in CMIP5 PI
+**N<sub>2</sub>O** = 200 ppb
+**CFC** = 0
-** Topography/bathymetry/coastlines/ice sheets **:
+**O<sub>3</sub>** = same as in CMIP5 PI
-This is one of the major changes compared to pre-industrial. Imposing the lgm ice sheets means imposing new coastlines, new topography/bathymatry and new ice sheet extent.
-For those modelling groups running the lgm experiment but not the deglaciation, we recommend to use the PMIP3 ice sheets/coastlines, for simulations for PMIP3-CMIP5 and CMIP6 to be strictly comparable.
+===== Topography/bathymetry/coastlines/ice sheets =====
-For those modelling groups who plan to run the deglaciation experiment (cf PMIP3 deglaciation working group), the new boundary conditions provided by Dick Peltier and Lev Tarasov can be used as well.
+This is one of the major changes compared to pre-industrial. Prescribing the lgm ice sheets means implementing new coastlines, a new topography/bathymetry and a new ice sheet extent.
-** Vegetation and land surface:**
+  * Modelling groups planning to run the lgm experiment but **not the deglaciation** are advised to use the [[pmip3:design:21k:final#ice-sheets_and_related_changes|PMIP3 ice sheets/coastlines]], so that PMIP3-CMIP5 and CMIP6 can be rigorously compared.
-Computed using a dynamical vegetation module,
+  * Modelling groups planning to **run lgm as the start of the the deglaciation experiment** (cf [[pmip3:wg:degla:index|PMIP3 deglaciation working group]]) can use the new boundary conditions provided by Dick Peltier and Lev Tarasov.
-Or prescribed as in PI, with phenology computed for models with active carbon cycle or prescribed from data
+===== Vegetation and land surface =====
+  * Computed using a dynamical vegetation module,
+  * or prescribed as in PI, with phenology computed for models with active carbon cycle
+  * or prescribed from data
-** Carbon cycle **
-Interactive, with atmospheric concentration prescribed and ocean and land carbon fluxes diagnosed as recommended in CMIP5
+===== Carbon cycle =====
-** Dust cycle **
+Interactive, with atmospheric concentration prescribed and ocean and land carbon fluxes diagnosed as recommended in CMIP5.
+For PCMIP: fully interactive with atmospheric concentration computed by the model.
+===== Dust cycle =====
 We invite the modelling groups planning to run simulations with an interactive dust cycle to comment on the most appropriate methodology for their model, in particular as to their ability to use a interactive vegetation description.
-** A note
+===== Note on the fresh water budget =====
+Modelling groups are advised to carefully check the fresh water budget in their lgm experiments in order to avoid unnecessary drifts of the ocean salinity. It can be necessary to route the snow which has fallen in excess on the ice sheets to the ocean. Given the change in coastlines, it is also sometimes necessary relocate the large rivers' estuaries on the coast.
+===== Global ocean salinity =====
-\\ \\ \\
+Add **1 PSU**.
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