780 / 2024-09-19 12:58:08
Freeze-thaw process boosts penguin-derived NH3 emissions and enhances climate-relevant particles formation in Antarctica
ammonia,Antarctica,Freeze-thaw,aerosol
Session 25 - IGAC-SOLAS: Chemistry and physics at surface ocean and lower atmosphere
Abstract Accepted
Ammonia volatilized from penguin excreta is a significant nitrogen source in Antarctic terrestrial ecosystems, exerting climatic effects through new particle formation. During penguin breeding seasons in Antarctic summer, frequent freeze-thaw events occur, causing pulses in gas emissions from penguin guano. However, little attention has been paid to the response of penguin-derived ammonia emissions to freeze-thaw events, and most models neglect this process. Here we investigate the contribution of penguin colonies to ammonia emissions and their climatic impacts based on both cruise observations and GEOS-Chem-APM simulations. High ammonia concentrations, with maximum exceeding 7000 ng/m3, were frequently observed over Southern Ocean and Prydz Bay, due to long-range transport of air masses originating from penguin colonies. Compared to simulations utilizing static emissions, incorporating freeze-thaw impact improves model performance, with penguin-derived NH3 emissions enhanced by 20-fold and reaching a total of 71 Gg NH3 across Antarctica in November. Elevated NH3 concentrations lead to a 30-300% increase in Antarctic secondary particle number concentrations through new particle formation, which in turn enhances cloud droplet number concentrations by 10-20% and modifies cloud properties. Our study suggests that penguin colonies can serve as “hotspots” for ammonia emissions, particularly during freeze-thaw events, which should be incorporated in climate models.