Solar cycle effects on the whole atmosphere

NCAR's Whole Atmosphere Community Climate Model (WACCM) is being used to study the atmospheric response from the surface to the lower thermosphere to changes in solar and geomagnetic forcing over the 11 year solar cycle. WACCM is a new general circulation model developed by scientists at ACD, HAO, and CGD. It incorporates MOZART-3 interactive chemistry that solves for both neutral and ion species.

Energy inputs include solar radiation and energetic particles, which vary significantly over the solar cycle (Figure 1: Irradiance at solar maximum and minimum used in the WACCM simulations (top), and their ratios (bottom)).

Simulations show large changes in composition and dynamical variables such as ozone and temperature (Figure 2: WACCM annual mean ozone and temperature differences (solar maximum - solar minimum) from the surface to approximately 130 km. Un-shaded regions are significant at the 95% level.), especially in the upper atmosphere, that are in good agreement with observations.

Many of ACD's models are available to the public. Please visit NCAR's Community Data Portal to download. Note that a short registration is required.