Publications by authors named "J Curtius"
Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon and the Atlantic and Pacific oceans. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of -30 °C and -50 °C.
View Article and Find Full Text PDFNew particle formation (NPF) in the tropical upper troposphere is a globally important source of atmospheric aerosols. It is known to occur over the Amazon basin, but the nucleation mechanism and chemical precursors have yet to be identified. Here we present comprehensive in situ aircraft measurements showing that extremely low-volatile oxidation products of isoprene, particularly certain organonitrates, drive NPF in the Amazonian upper troposphere.
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- Ammonia emissions in Southeast Asia significantly impact air pollution and the development of the Asian Tropopause Aerosol Layer (ATAL), particularly during summer when the South Asian monsoon is active.
- The study utilizes the EMAC chemistry-climate model to analyze how ammonia influences particle formation, revealing a tenfold increase in particle creation during the day, especially within the monsoon's upper troposphere and lower stratosphere (UTLS).
- Findings indicate that while ammonia enhances cloud condensation nuclei (CCN) concentrations and aerosol optical depth (AOD), its effect on aerosol mass in the ATAL is comparatively limited, suggesting a complex relationship between ammonia, particle growth, and aerosol composition.
Article Synopsis
- * The study found that particle formation rates due to ion-induced processes are stable across temperature changes, while neutral particle formation rates increase significantly when temperatures drop from +10 °C to -10 °C.
- * Despite higher ionization rates, the formation of charged clusters is unlikely to be enhanced in upper tropospheric conditions; instead, neutral nucleation is expected to dominate, with humidity having little effect unless extremely low.
Article Synopsis
- Aerosols from gas-to-particle processes significantly contribute to urban smog and haze, particularly through the formation of ammonium nitrate, which can thrive in polluted city conditions.
- Urban areas face complex variations in temperature and gas concentrations, influencing how quickly aerosols can form and grow.
- Experimental results from CERN's CLOUD chamber reveal that rapid temperature fluctuations can enhance nanoparticle growth, highlighting the influence of inconsistent ammonia emissions in cities on aerosol dynamics.