Forcings in GISS Climate Model


Ozone is a greenhouse gas and short-wave absorber whose concentrations are affected by emissions of reactive substances into the atmosphere and changes in climate and circulation. Pre-CMIP5, the effects in the stratosphere and troposphere were frequently calculated and applied separately, but while there are distinct processes at work in each regime, the connections imply that this should be calculated all-together (Shindell et al., 2013).

Changes in tropospheric ozone over the historical period are driven by increases in emissions of ozone precursors (such as CH4, NOx, VOCs etc.), changes in climate that affects reaction rates and fluxes from the stratosphere. Stratospheric ozone is affected by emissions of ozone depleting substances (ODS), such as CFCs and N2O, as well as changes in climate and circulation (including solar forcing).

CMIP5 Forcing

In historical simulations without interactive chemistry, ozone changes are included as an input to the model and those inputs can be downloaded here (netCDF file, 11MB).

In interactive simulations, the ozone concentrations are an output from the model, and can be downloaded directly from the CMIP5 archives (Shindell et al., 2013).

Ozone radiative forcing CMIP5

Figure. Historical evolution of ozone burdens and radiative forcing. Time varying instantaneous tropopause radiative forcing due to ozone (W m−2) from the transient simulations (top; as longwave (LW), shortwave (SW) and net), total column ozone (DU) in the model and in ERA reanalysis (middle), and iRF along with the tropospheric ozone burden (DU) and ozone RF estimated using the tropospheric burden times the normalized radiative forcing (NRF) (bottom). The solid red symbols in the lower panel show the whole atmospheric (square) and tropospheric (circle) ozone RF calculated in the offline radiative transfer model (From Fig. 15 in Shindell et al., 2013).


Please address inquiries about these data to Dr. Gavin Schmidt.


Miller, R.L., G.A. Schmidt, L.S. Nazarenko et al., 2014: CMIP5 historical simulations (1850-2012) with GISS ModelE2. J. Adv. Model. Earth Syst., 6, no. 2, 441-477, doi:10.1002/2013MS000266.

Shindell, D., G. Faluvegi, L. Nazarenko, K. Bowman, J.-F. Lamarque, A. Voulgarakis, G.A. Schmidt, O. Pechony, and R. Ruedy, 2013: Attribution of historical ozone forcing to anthropogenic emissions. Nature Clim. Change, 3, 567-670, doi:10.1038/nclimate1835.

Shindell, D.T., O. Pechony, A. Voulgarakis, G. Faluvegi, L. Nazarenko, J.-F. Lamarque, K. Bowman, G. Milly, B. Kovari, R. Ruedy, and G. Schmidt, 2013: Interactive ozone and methane chemistry in GISS-E2 historical and future climate simulations. Atmos. Chem. Phys., 13, 2653-2689, doi:10.5194/acp-13-2653-2013.

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This page was written by Dr. Gavin Schmidt.

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