Abstract View
New Particle Formation during the CAMP2Ex Campaign: Statistics and Impact of Emission Sources
QIAN XIAO, Jiaoshi Zhang, Yang Wang, Luke Ziemba, Ewan Crosbie, Edward Winstead, Claire Robinson, Jeffrey Reid, Josh DiGangi, Glenn Diskin, Sebastian Schmidt, Armin Sorooshian, Miguel Hilario, Sara Woods, Paul Lawson, Ryan Bennett, Jian Wang, Washington University in St. Louis
Abstract Number: 470
Working Group: Aerosols, Clouds and Climate
Abstract
Nucleation and subsequent growth of new particles occur frequently within the upper troposphere over tropical oceans, and this new particle formation (NPF) presents a globally important source of cloud condensation nuclei (CCN). However, there have been few studies of NPF at lower altitudes over the tropical oceans. In addition, the impact of anthropogenic emissions and biomass burning on the NPF remains unclear. In this study, we examine NPF in lower and mid troposphere in Southeast Asia using airborne measurements during the recent the Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP2Ex). CAMP2Ex took place from 25 August through 5 October 2019, including both late southwest and early northeast monsoon phases. Recent NPF events, as evidenced by elevated concentrations of newly formed particles (i.e., particles with diameter between 3 and 10 nm), were observed during 4% of the total flight time (5 out of 128 hours). The frequency of NPF increases with altitude, reaching 49% above altitude of 8000 m. All NPF was observed at altitude above 3000 m and coincided with elevated RH, suggesting that new particles were formed in the outflow of convective clouds, where both the temperature and existing particle surface area are low. Based on trace gas measurements, airmasses are categorized as background, biomass burning, and pollution. Under the background condition, the highest concentrations of newly formed particles were mostly observed above 8 km. Weaker NPF was observed at lower altitudes under the background condition. Below 8 km, NPF mostly occurred in airmasses influenced by biomass burning or pollution and was facilitated by enhanced radiation contributed by clouds. NPF was more frequent during the more convectively active southwest monsoon period than more quiescent northeast monsoon, again indicating the impact of airmass origin and convective activities on the NPF in the lower to mid troposphere in the region.