Urban Air Pollution, Tropospheric Chemistry, and Climate Change: An Integrated Modeling Study
Chien Wang MIT
Linking Urban Pollution, Tropospheric Chemistry and Climate Change
Impact of urban air pollution on global tropospheric chemistry and climate (e.g., tropospheric O3 and NOx budgets, radiative forcing by O3 and aerosols); Impact of future climate change on urban air pollution and tropospheric chemistry (e.g., effects of clouds, UV, precipitation, H2O, and temperature on reaction rates); Interaction between urban/tropospheric chemistry and climate under various emissions policies; Anthropogenic aerosols' impact on human
Integrated Modelling Study
Climate-chemistry interactions require models with integrated components of atmosphere, ocean, tropospheric chemistry, emissions (policy and nonpolicy), and ecosystem; Integration time: 10 years for tropospheric chemistry studies (primarily due to CH4 and O3 simulation as well as aerosol forcing assessment), 100 years for tropospheric chemistry and climate interaction studies;
Subgrid scale nature of urban and fast tropospheric chemistry as well as lightning production of certain chemical species in current global models with resolution coarser than ~100 km requires adequate parameterizations for relevant processes; Data base (measurement and emissions); Computational efficiency (parallel, esp. distributed memory computing)
MIT Interactive Chemistry-Climate Model
Atmospheric Chemistry Model
25 Chemical species 4 Aerosol groups Advection, convection, and mixing Gaseous and aqueous reactions Wet and dry deposition
Concentrations of chemicals
Climate Model
MIT 2DLO, NCAR CCM/CSM, MIT AIM/OGCM
Circulation and state of atmosphere Land and ocean Clouds and Precipitation Radiation
Urban Air Pollution Model Natural Emission Model Ocean Carbon Model EPPA and Emission Preprocessor
Terrestrial Ecosystem Model
NPP, NEP, soil carbon pool
Winds, T, H2O, precipitation and radiative fluxes
Urban Air Pollution Model and Global Chemistry Model
Projected Future Increases of Emissions (Emissions/Emissions of 1995; MIT EPPA)
4 3.5 3
Ratios
SO2 BC OC
2.5 2 1.5 1 0.5 1995
2010
2025
2040 2055 Year
2070
2085
2100
Barrow (40W 70N)
50.00
OBS 1989 Model
Surface BC in ng/M^3
Mauna Loa (155.4W 19.3N)
140.00 120.00
45.00 40.00 35.00 30.00 25.00 20.00 15.00 10.00
OBS 1992 Model
Surface BC in ng/M^3
100.00 80.00 60.00 40.00 20.00 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
5.00 0.00 1 2 3 4 5 6 7 8 9 10 11 12 Month
Amsterdam Island (77.3E 37.5S)
14.00 12.00
Surface BC in ng/M^3
OBS 1991 Model
South Pole (102W 87S)
3.50 3.00 OBS 1989 Model
Surface BC in ng/M^3
10.00 8.00 6.00 4.00 2.00 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
2.50 2.00 1.50 1.00 0.50 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
Summary
Integrated models are needed for linking urban air pollution, tropospheric chemistry, and climate; required integration time varies from 10 - 100 years depending on the given topics; Adequate parameterizations of urban scale air chemistry and other subgrid scale chemical processes in global models are critical to modeling results; Future black carbon emissions may increase according to the MIT EPPA Model;
Modeled radiative forcing of aerosols is highly uncertain, multiple year integrations with uncertainty analyses are needed for assessment;
Policy and health issues related to urban air pollution and anthropogenic emissions of aerosols need to be explored and inclusion of interaction between tropospheric chemistry and climate change is