Aerosol effects on clouds operate at spatial scales of short-lived cloud updrafts (typically 100 m- 100 km), yet exert a global effect on climate over multiple decades. The multiscale nature of these indirect effects on the planetary energy balance presents particular challenges to climate modeling, which has led to large uncertainties in estimates of indirect effects. The most difficult types of aerosol indirect effects to quantify are those for which the aerosol sources are controlled by complex interactions of ecosystems with climate, such as the aerosol emissions from ocean phytoplankton and from wildfires in forests. This project addresses these challenges through a combination of advanced parameterizations, explicit modeling, and observations with a multi-institutional,multi-disciplinary team of experts. Advanced parameterizations of aerosol effects on stratocumulus, shallow cumulus and deep cumulus clouds that have been or are being developed under separate funding will be brought together into a common framework for multidecadal simulations with coupling to the ocean. The simulations with and without aerosols will be examined to determine the influence of aerosol indirect effects on decadal climate variability. This evaluation will be accomplished by relating climate-scale changes in oceanic and atmospheric conditions over the Pacific to the sensitivities of regional ocean-atmosphere interactions to aerosols along the west coast of North America and consequent atmospheric conditions over the entire U.S.
The broader educational impacts of the research will be realized through: (1) Promotion of teaching, training and learning through development and piloting of an informal science education program targeting an underserved audience; (2) Broadened participation of underrepresented groups--in this case, retired and elderly people--in scientific learning; (3) Enhancement of infrastructure for teaching through partnerships with an established educational organization; (4) Broad dissemination of results through presentations, peer-reviewed publications and via the web; and (5) Societal benefits in terms of improved understanding of climate science and the related ethical issues. In addition to outreach activities, there will be at least three graduate students who will each receive three years of training in coupled Earth system modeling as part of this project.
