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Particles are vital for climate regulation, influencing key processes such as cloud formation and radiation balance. Historically, urban climate research has concentrated predominantly on primary particles emitted directly from sources like vehicle exhaust and industrial operations. Recently, however, the focus has shifted toward new particles formed through atmospheric reactions, which have often been underrepresented in studies regarding their climatic effects.
A new study featured in One Earth presents strong evidence indicating that the climate impacts of new particles in urban settings have been greatly underestimated.
“For a precise evaluation of the climate effects linked to particles, it is crucial to have extensive long-term vertical observations,” states Academician Markku Kulmala from the Institute for Atmospheric and Earth System Research INAR at the University of Helsinki. This call for improved observational practices highlights the intricate nature of atmospheric processes and the necessity of collecting data from varying altitudes to deepen our understanding of urban aerosol behavior.
Enhanced particle formation aloft in urban areas
Employing sophisticated measurement technologies at a 325-meter meteorological tower in Beijing, the research team investigated particle formation at different altitudes above the city. The findings revealed that particle formation is notably more vigorous at higher elevations, driven by factors such as elevated sulfuric acid concentrations and increased humidity. This situation is particularly relevant in urban settings, where pollution levels and atmospheric dynamics can fluctuate significantly, resulting in distinct growth mechanisms for new particles compared to those in rural locales.
“The heightened particle formation at higher altitudes implies that ground-level measurements, while informative, may not adequately represent the entirety of particle dynamics in densely populated urban areas,” explains Wei Du, a prominent researcher involved in the study. This perspective accentuates the need to scrutinize the atmosphere above the cityscape to better understand urban atmospheric processes.
The climate effects of new particles
As gaseous precursors from human activities ascend to elevated layers of the atmosphere, they facilitate the growth of particles, which can become effective cloud condensation nuclei (CCN) essential for cloud formation and local climate governance. The study contends that the role of new particles in influencing CCN has likely been underestimated by around 20%. Consequently, grasping the vertical aspects of urban atmospheric dynamics is crucial for fully understanding the influence of particulate matter on climate.
The ramifications of this research extend beyond theoretical discussions, presenting substantial implications for policy-making and urban development.
“As cities continue to tackle issues of air pollution and climate change, a clearer understanding of the vertical distributions of atmospheric processes can help formulate more effective strategies to mitigate their effects on climate and public health,” Wei asserts.
This study exemplifies a collaborative initiative involving scientists from the University of Helsinki, the Chinese Academy of Sciences, and other international partners.
“The Beijing 325 m Meteorological Tower serves as a unique research facility for atmospheric and climate science within megacities. We are enthusiastic about collaborating with global partners to collectively address the challenges posed by climate change,” remarks Yele Sun, a Professor at the Chinese Academy of Sciences.
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