3.3 WACCM & IGAC/SPARC Chemistry-Climate Model Initiative (CCMI)

Simulations using the Community Earth System Model version 1 - Whole Atmosphere Community Climate Model (CESM1-WACCM) were conducted in support of the International Global Atmospheric Chemistry / Stratosphere-troposphere Processes And their role in Climate (IGAC/SPARC) Chemistry Climate Model Initiative (CCMI). The CESM1-WACCM simulations performed under various chemical composition scenarios performed for CCMI are designed to support upcoming international assessments. The WACCM group completed seven different hindcast and projection scenarios that spanned the period between years 1850 and 2100 – a total of over 2600 simulations years. The results have been made available on the NCAR Earth System Grid.

Improvements in CESM1-WACCM for CCMI included an improved orographic gravity wave forcing that reduced the cold bias in Antarctic polar temperatures [Garcia et al., 2016]. These improvements, coupled with an enhanced representation of both tropospheric and stratospheric chemistry greatly improved comparisons with ground-based, aircraft, and satellite observations. An example of these results are shown in Figure 1. Here, the southern hemisphere total column ozone (TOZ) polar cap average is shown for October. The WACCM ozone hole chemistry as described in Wegner et al., [2013] and Solomon et al., [2015] accurately represents the observed ozone depletion. The WACCM model results suggest that the polar TOZ will recover to 1980 conditions around year 2060.

Sample template image
Figure 1. Polar cap total column ozone for October. Black squares represent observations based on satellite observations. Purple squares are results from the WACCM model run in specified dynamics model. The input meteorological fields are taken from NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA) reanalysis. Blue and Green symbols represent two versions of WACCM forced with a data ocean and interactive ocean respectively.

PUBLICATIONS:

Eyring et al., Overview of IGAC/SPARC Chemistry-Climate Model Initiative (CCMI) Community simulations in Support of Upcoming Ozone and Climate Assessments, SPARC newsletter, n40 –January 2013.

Garcia, R. R., A. K. Smith, D. E. Kinnison, A. de la Cámara, D. Murphy, Modification of the gravity wave parameterization in the Whole Atmosphere Community Climate Model: Motivation and results, in press, J. Atmos. Sci., 2016.

Solomon, S., D. E. Kinnison, J. Bandoro, R. R. Garcia, Simulations of Polar Ozone Depletion: An Update, J. Geophys. Res., 120, 7958-7974, doi:10.1002/2015JD0233652015.

Wegner, T, D. E. Kinnison, R. R. Garcia, S. Madronich, and S. Solomon, Polar Stratospheric Clouds in SD-WACCM4, J. Geophys. Res., VOL. 118, 1-12, doi:10.1002/jgrd.50415, 2013.