INTRODUCTION The Coupled Carbon Cycle Climate Model Intercomparison Project (C4MIP) is designed to compare and analyze the feedbacks between the carbon cycle and climate in the presence of external climate forcing. Such feedbacks are likely to be mediated on the one hand by altered forcing of the ocean and terrestrial carbon cycles and on the other by the impact of altered CO2 concentrations in the atmosphere resulting from this forcing. The basic approach is to include models of the terrestrial and ocean carbon cycles in existing OAGCMs and run the augmented model with and without these feedbacks active. This note describes a protocol for the first phase of the intercomparison. the experiment described here is not the full-fledged coupled experiment sketched above but rather a necessary prerequisite step. We have chosen this incremental approach for two reasons. Firstly the full-form experiment is an ambitious task even for the best-equipped modelling groups. It has thus far been performed by two groups with several more constructing the required models at the time of writing. It is likely then that an intercomparison exercise of the full-form experiment is premature. We will, however, be constructing a protocol for this experiment shortly The second reason is that the terrestrial-only experiment we describe here is required anyway for the analysis of the full-form experiment. It is well understood that the response of a system to a feedback is partly conditioned by the basic state. Thus we need to understand and, if possible, test the behaviour of the coupled system without the strong forcing of the climate change experiments. We expect the experiment to yield valuable information on the behaviour of the coupled land-atmosphere system. Several other components of the full-form system are already subjects of paralel analyses. The Noces experiment will explore the behaviour of the ocean carbon cycle subject to observed climate and CO2 forcing. The Coupled Model Intercomparison Project (CMIP) will provide analyses of the climate sensitivity of the physical climate models used in C4MIP. Finally the Climate of the 20th Century (C20C) experiment will explore the sensitivity of the land-atmosphere physical models to observed forcing by SSTs and radiative forcing. Where possible we hope to make our experiment compatible with these so that the sensitivity information they yield is directly applicable to C4MIP. To that end we will use forcings for the physical climate models taken from Noces and C20C (these are very similar) and for the carbon cycle from Noces. The forcing are the atmospheric CO2 concentration of the 19th and 20th century inferred from records in firn and ice cores, the historical SSTs data (HadISST1.1), and the Ramankutty data for land cover changes. EXPERIMENT DESCRIPTION - Model requirements An atmospheric GCM with a capability to transport tracers A terrestrial carbon cycle model that can account for land use changes Required run : The historical run with forced CO2 and SSTs and inclusion of land cover change Optional but highly encouraged: - Historical run as above but with SST forcing only - Historical run as above but with CO2 and SST forcing only - Ensemble runs for the 1980-2000 period - Spin up. ********* The spin up is in two phases: 1) Equilibrate the model to 1850 CO2 and roughly preindustrial climate. This may take a while so the idea is to run the terrestrial model off-line 1a) run the AGCM with 1875-1899 SSTs and 1850 CO2. Save all variables needed to run the terrestrial model. 1b) run the terrestrial carbon cycle model offline for 1,000 years (cycling the 25 years climate forcing) 1c) Run the coupled AVGCM for the 1875-1899 period with 1850 CO2 and the terrestrial state from the 1000 year integration. 2) Run the coupled AVGCM forced by the same 1875-1899 SSTs but increasing CO2 from 1850 to 1899 - Historical run : 1900-2000 **************************** Continue the run but with the actual SSTs (1900-2000) and the observed atmospheric CO2. Both will be available from the project host site. For both pre-run and historical run, land use changes taken from Ramankutty/Goldewijk will be imposed. The methodology for calculating carbon cycle fluxes following land cover changes will be taken from the Grand Slam CCMLP experiment (see Grand Slam protocol) Ensemble runs (optional) ************* In order to estimate the internal variability of the coupled AVGCM it is proposed to run an ensemble of 5 20 years simulations (1980-2000) with different initial conditions (e.g. 5 consecutive days). To do so, it is asked to save the relevant restart fields (January 1 to 5 of 1980) Atmospheric CO2 transport ************************* Terrestrial CO2 net fluxes should be transported in the AGCM for the period 1960-2000). However, the CO2 will be a passive tracer that does not interact with the radiation and the carbon cycle of the model. Historical fossil fuel co2 fluxes (from Andres et al) and geochemical ocean uptake (to be decided) should also be transported SEPARATELY in the GCM. These fossil fuel and ocean flux fields will also be available from the project host site. Diagnostics (format imposed: NETCDF) *********** Monthly time series of 3D fields: Temperature, specific humidity Atmospheric CO2 concentration from each tracer (fossil, ocean and land) 2D fields: OLR Daily time series of 2D surface fields: Surface temperature, precipitation, surface short wave (up, down), surface long wave (up,down) wind stress, pressure, soil temperature, soil water content + any other field needed to run the terrestrial carbon cycle offline latent heat flux, sensible heat flux, LAI, GPP, NPP, NEP, gs Hourly time series of atmospheric CO2 at station locations (see annex) Monthly time series of 2D fields All terrestrial carbon pools and fluxes (including produts and conversion flux from land use) Carbon pools and fluxes should be saved per PFT if fractional covers are accounted for) vegetation cover Formats and, with help from PCMDI, software for producing output in the correct format will be provided at the project host site. ANNEX: Atmospheric CO2 station list Station name Lat Long Elev. Wind Topo Bass Strait/Cape Grim -40.38 144.39 500 SW NS Bass Strait/Cape Grim -40.38 144.39 1500 SW NS Bass Strait/Cape Grim -40.38 144.39 2500 SW NS Bass Strait/Cape Grim -40.38 144.39 3500 SW NS Bass Strait/Cape Grim -40.38 144.39 4500 SW NS Bass Strait/Cape Grim -40.38 144.39 5500 SW NS Bass Strait/Cape Grim -40.38 144.39 6500 SW NS Alert, Greenland 82.45 -62.52 210 SW Amsterdam Island -37.95 77.53 150 Ascension Island -7.92 -14.42 54 Assekrem, Algeria 23.18 5.42 2728 NS St. Croix, Virgin Is. 17.75 -64.75 3 Azores 38.75 -27.08 30 Baltic Sea, Poland 55.50 16.67 7 Baring Head St., NZ -41.41 174.87 80 S,SW Bermuda West 32.27 -64.88 30 Barrow, Alaska 71.32 -156.60 11 E,NE Black Sea, Romania 44.17 28.68 3 NE Carr, CO 40.90 -104.80 3000 NS Carr, CO 40.90 -104.80 4000 NS Carr, CO 40.90 -104.80 5000 NS Carr, CO 40.90 -104.80 6000 NS Cold Bay, Alaska 55.20 -162.72 25 Cape Ferguson, Aust. -19.28 147.06 2 E Cape Grim, Tasmania -40.68 144.68 94 SW Christmas Island 1.70 -157.17 3 Mt. Cimone St., Italy 44.18 10.70 2165 NS Cape Meares, OR 45.48 -123.97 30 W,NW Cape Rama, India 15.08 73.83 60 S,SE Crozet, Indian Ocean -46.45 51.85 120 Cape St. James, Canada 51.93 -131.02 89 W Darwin, Australia -12.42 130.57 3 W,NW Easter Island -29.15 -109.43 50 Estevan Pt, BC, Canada 49.38 -126.55 39 W Guam 13.43 144.78 2 Dwejra Pt., Malta 36.05 14.18 30 Halley Bay, Antarctica -75.67 -25.50 10 Hungary 46.95 16.65 300 Storhofdi, Iceland 63.25 -20.15 100 North Carolina 35.35 -77.38 60 North Carolina 35.35 -77.38 500 NS Canary Islands 28.30 -16.48 2360 NS Jubany St., Antarctica -62.23 -58.82 15 Key Biscayne, FL 25.67 -80.20 3 S Kosan, Rep. of Korea 33.28 126.15 72 Kumukahi, Hawaii 19.52 -154.82 3 Wisconsin tower 45.93 -90.27 500 NS Wisconsin tower 45.93 -90.27 850 NS Lampedusa, Italy 35.52 12.62 85 Mawson St., Antarctica -67.62 62.87 32 Mould Bay, Canada 76.25 -119.35 58 Sand Island, Midway 28.22 -177.37 4 Mauna Loa, Hawaii 19.53 -155.58 3397 NS Minamitorishima, Japan 24.30 153.97 8 Macquarie Island -54.48 158.97 12 Olympic Peninsula, WA 48.25 -124.42 488 W Plateau Rosa St., Italy 45.93 7.70 3480 NS Palmer St., Antarctica -64.92 -64.00 10 Qinghai Province, PRC 36.27 100.92 3810 NS Ragged Pt., Barbados 13.17 -59.43 3 Ryori St., Japan 39.03 141.83 230 E Schauinsland, Germany 48.00 8.00 1205 NS South China Sea 3.00 105.00 15 South China Sea 6.00 107.00 15 South China Sea 9.00 109.00 15 South China Sea 12.00 111.00 15 South China Sea 15.00 113.00 15 South China Sea 18.00 115.00 15 South China Sea 21.00 117.00 15 Sable Island, NS, Canada 43.93 -60.02 5 E Mahe Island, Seychelles -4.67 55.17 3 Shemya Island, Alaska 52.72 174.10 40 Shetland Is., Scotland 60.17 -1.17 30 Samoa -14.25 -170.57 42 South Pole -89.98 -24.80 2830 Atlantic Ocean, Norway 66.00 2.00 7 Pacific Ocean, Canada 50.00 -145.00 7 Syowa, St., Antarctica -69.00 39.58 11 Tae-ahn Pen., Korea 36.73 126.13 20 Wendover, Utah 39.90 -113.72 1320 Ulaan Uul, Mongolia 44.45 111.10 914 Westerland, North Sea 55.00 8.00 8 W Sede Boker, Israel 31.13 34.88 400 NW Zeppelin St., Norway 78.90 11.88 474 Adrigole, Ireland 52.00 -10.00 50 SW Fraserdale, Ont, Canada 49.88 -81.57 210 Kitt Peak, AZ 31.90 -111.60 2090 NS Lauder, NZ -45.00 169.70 370 S Neumayer, Antarctica -71.60 -8.30 16 Scripps Pier, CA 32.83 -117.27 14 W Table Mtn., CA 34.40 -117.70 2258 NS Trinidad Head, CA 41.05 -124.15 109 W Columns are 1 Name 2 Latitude 3 Longitude 4 Elevation (meters), 5 Wind : model sampling should be moved to the next gridcell according to the given wind direction. 6 Topo: Topography of the site: NS means nonsurface so that we don't believe the model has a hope of matching the topography and you should pretend it's free atmosphere.