The Whole Atmosphere Community Climate Model (WACCM) is a comprehensive numerical model, spanning the range of altitude from the Earth's surface to the thermosphere (about 150 km, or 93 miles).
The development of WACCM is an inter-divisional collaboration that unifies aspects of the upper atmospheric modeling of the High Altitude Observatory (HAO), the chemical modeling of the Atmospheric Chemistry Division (ACD), and the lower atmospheric modeling of the Climate and Global Dynamics (CGD) division, using the NCAR Community Climate System Model (CCSM) as a common numerical framework.
WACCM includes a detailed chemical package for the middle atmosphere (above 10 km, or 6 miles at mid-latitudes) for both neutral and ion species, and takes into account the effects of variability in solar radiation and of particle precipitation in the Earth’s atmosphere (the aurora borealis or northern lights).
It is possible to study problems like the ozone hole (See Figure 1) with WACCM.Modelers of the WACCM group are studying the complex climate interactions that accompany ozone depletion, the interactions with solar irradiance, and their potential effects on the climate of the troposphere.
In the WACCM project we are not solely interested in the middle atmosphere.
In fact, we are interested in the coupling between the climate changes that take place in the middle atmosphere and weather or climate changes that may follow
in the lower atmosphere.
For example, during northern winter (December through February) the stratospheric winds around 30 km (about 19 miles above the surface) at mid-latitudes usually blow from the west towards the east (also called westerly winds).
Typically, these stratospheric westerly winds are very strong, and the stratospheric wind system is known as a strong vortex.
Once every 1-2 years, it happens that stratospheric winds reverse and flow in the opposite direction: these events are then called stratospheric warmings, and the stratospheric wind system is referred to as a weak vortex.
[There is a] possibility of coupling between the middle and the lower atmosphere, which could affect tropospheric weather.
CCSM Scientific Steering Committee (SSC) Members
ESSL (Earth & Sun Systems Laboratory)