CAREER: Exploring the Role of Vapor Buoyancy in Clouds, Circulation and Climate

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).

The buoyancy effect of water vapor arises from its lower molecular mass compared to dry air. Because water vapor is a trace gas in Earth’s atmosphere, its buoyancy effect is often considered to be negligibly small. It is thus overlooked in studies of climate and large-scale dynamics.

However, the principal investigator (PI) has recently shown that cold air rises in the tropical free troposphere due to this buoyancy effect of water vapor – a finding that calls for greater attention on the topic. Hence, to advance our understanding of vapor buoyancy, the work will investigate how vapor buoyancy affects temperature, clouds, and circulation in the tropical atmosphere.

This project will help mitigate the uncertainty surrounding future climate change and improve the representation of vapor buoyancy in climate models. Additionally, the project will create new college course materials and establish an education program that provide active learning experiences for high school and university students in the Sacramento area, who are mostly from underrepresented groups.

The project will test the hypothesis that vapor buoyancy warms the dry regions of the tropical atmosphere, which can subsequently affect outgoing longwave radiation, static stability, cloud distribution and, thereby, climate sensitivity. The research approach includes analyzing satellite observations, performing numerical simulations of varying complexity, and diagnosing state-of-art climate simulations.

The education program will improve teaching on atmosphere and climate at both the university and K-12 levels by implementing hands-on rotating tank experiments. For university students, the PI will develop new course modules and class projects on how water vapor influences large-scale circulations, complementing existing materials that mainly focus on dry dynamics. The PI will also organize training workshops for high-school teachers in the Sacramento area.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.