White paper: Atmospheric Chemistry impacts on the land biosphere Phillip Cameron-Smith and Natalie Mahowald Processes: 1.[AC-direct] Ozone Damage (a strong oxidant, it can damage leaves), 2.[AC-direct] Nitrogen Deposition (fertilizes soils with nitrogen), 3.[AC-direct] Increase in Diffuse Radiation (aerosols scatter solar radiation, increasing the proportion of diffuse to direct light at the surface), 4.[AC-direct] Acid Rain (leaches nutrients out of soils), 5.[AC-indirect] Precipitation (quantity, frequency, timing, & state of precipitation are all important), 6.[AC-indirect] Temperature (the radiative impact of reactive GHGs and aerosols have an effect on global warming), 7.[AC-indirect] CO2 Fertilization (in situ oxidation of carbon monoxide, methane, and higher hydrocarbons is equal to 25% of anthropogenic CO2 emissions),

Goals for each interaction Estimate the importance of each of the land biosphere stresses affected by atmospheric chemistry and aerosols. Incorporate the important feedbacks into CCSM as appropriate. Estimate whether online chemistry is required in order to correctly incorporate the interactions within the system.

Model development required Too much— ignore for now Ozone surf. Conc ok? Some clm dev.

Tasks for each process 1. Spin up CAM/CLM-CN simulations for 2000 and 2050 (use asynchronous runs to get to equil. faster) 2. Conduct offline land model runs

Tasks (cont) 3. If land only response is significant, see if physical climate responds in CAM/CLM- CN case (no chem) 4.If physical climate responded, get chemical/physical response in coupled CAM-CHEM/CLM-CN runs 5.If task 4 results in big differences from Task 1, iterate again.

Evaluation of importance

Carbon cycle-atmospheric chemistry interactions (Dave Erickson, Don Wuebbles) CO2 production in atmosphere (HC, CO) Predict biogeochemical cycles of CH4 and CO2 Methane (ongoing development, also identified by BGC WG) –Requires rice paddies, cows??? –Interactive wetland (need better surface hydrology) –High latitude carbon cycle, including wetland (without surface hydrology interactions) will be discussed at next week’s joint land/BGC WG meeting

Atmospheric chemistry/biogeochemistry from BGC white paper (2004) Nitrogen deposition interactions (ongoing) Reactive chemistry interactions with biogeochemistry, clouds –Ozone interactions –Anthropogenic Aerosols interactions –Natural aerosol/cloud/precip interactions –Oxidative capacity changes with climate Land use interactions with emissions, also through fire Gap: methane

What we need to do WG agree to plan –Did we miss something important? –More complicated than we planned? Personnel identified? –Little development (ozone interaction, coupler interaction) –Spin up and runs need to be done –Analysis