March 11, 2009 | NCAR scientists are working on a bigger, bolder version of WACCM (the Whole Atmosphere Community Climate Model), called WACCM-eXtension, or WACCM-X for short. The enhanced version extends the model, which begins at Earth’s surface, all the way through the upper thermosphere and ionosphere (the ionized region of the thermosphere) to an altitude of about 310 miles (500 kilometers).

An interdivisional effort, WACCM incorporates HAO’s modeling of the upper atmosphere, ACD’s modeling of the middle atmosphere’s chemistry, and CGD’s modeling of atmospheric dynamics and the lowest portion of the atmosphere, using the Community Climate System Model (CCSM) as a common numerical framework.

WACCM-X will give scientists a tool to study coupling between the lower and upper atmosphere and connect tropospheric climate with space weather. It will also help them better understand climate change throughout the whole atmosphere, which is particularly important because carbon dioxide emissions impact the upper atmosphere as well as the lower.

“The upper atmosphere region is really interesting because it’s driven by events from above, such as solar storms, as well as from the troposphere below, making it important to have a model that can capture both,” says NCAR scientist Hanli Liu.

The modelers recently finished incorporating the thermosphere into WACCM-X and are working with the community to validate it against empirical models and observations. The ion chemistry of the model is in place as well. The team is currently developing modules for the ionosphere’s electrodynamics and hopes to implement some essential components by the end of the year. When complete, they’ll use the model to study space weather events, like the impacts of coronal mass ejection on the Earth atmosphere. They hope to eventually couple WACCM-X to magnetosphere and plasma models, which simulate atmospheric processes at even higher altitudes.

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