Atmospheric aerosols represent a key uncertainty in understanding the climate system and climate change, and the contribution of primary biogenic aerosols is not included in current global budgets. Recent work indicates that pollen, a primary biogenic aerosol, can break up into fine particulate matter, act as giant cloud condensation nuclei (CCN), and influence the formation of ice nuclei. This project will address three scientific questions to quantify the climatic relevance of pollen in the atmosphere: (1) What are the magnitude and spatial distribution of pollen emissions from the biosphere? (2) What are the processes that allow pollen to act as CCN and how likely are they to occur? (3) What are the magnitude and spatial distribution of direct and first indirect radiative forcing from pollen aerosols?
The project will develop and integrate a pollen aerosol emissions module in a regional climate model, evaluate the ability of pollen to act as a CCN through experimental studies, and assess the direct and indirect effects of pollen on regional radiative forcing through decadal scale regional climate simulations. The scientific outcomes will provide an estimate of the magnitude of the contribution of pollen to the aerosol budget over fine spatial and temporal scales and their ultimate impact on long-term climate.
Broader impacts include the following: (1) An educational program, the Green Roof Project, will establish two meteorological and pollen monitoring stations at middle schools in Detroit public to introduce middle school students to hypothesis development, data collection, and data analysis and interpretation. Data from the Green Roof Project will inform the pollen emissions model development. (2) Integration of the Green Roof Project and research on biosphere-atmosphere interactions with the University of Michigan graduate and undergraduate education, and (3) International education through a partnership with the International Centre for Theoretical Physics to train scientists from developing nations on the role of biosphere-atmosphere interactions. This project will benefit society by assessing the contribution of primary biogenic aerosols like pollen to climate variability, the impact of landscape change on air quality, and the role of pollen emissions and transport in asthma and public health.
