New particle formation in marine atmosphere during seven cruise campaigns

Abstract

Abstract. To study the particle number concentration, size distribution and new particle formation (NPF) events in marine atmosphere, we made measurements during six cruise campaigns over the marginal seas of China in 2011-2016 and one 10 campaign from the marginal seas to the Northwest Pacific Ocean (NWPO) in 2014. We observed relatively frequent NPF events in the atmosphere over the marginal seas of China, i.e., 23 out of 126 observational days with the highest occurrence frequency in fall, followed by spring and summer. 22 out of 23 NPF events were analyzed to be associated with the long-range transport of continental pollutants based on 24-hr air mass back trajectories and the pre-existing particle number concentrations largely exceeding the clean marine background, leaving one much weaker NPF event to be likely induced by oceanic precursors 15 alone and supported by multiple independent evidences. Although the long-range transport signal of continental pollutants can be clearly observed in the remote marine atmosphere over the NWPO, NPF events were observed only in 2 days out of 36 days. The nucleation mode particles (<30 nm), however, accounted for as high as 40%13% of the total particle number concentration during the NWPO cruise campaign, implying that there were many undetected NPF events in the sea-level atmosphere or above. 20To better characterize NPF events, we introduced a term, i.e., the net maximum increase in nucleation mode particles number concentration (NMINP) and correlated it with formation rate of new particles (FR). We found a moderately good linear correlation between NMINP and FR at FR 8 cm -3 s -1 , but there was no correlation at FR >8 cm -3 s -1. The possible mechanisms were argued in terms of roles of different vapor precursors. We also found a ceiling existing for the growth of new particles from 10 nm to larger size in most of NPF events. We thereby introduce a term, i.e., the maximum geometric 25 median diameter of new particles (Dpgmax) and correlate it with the growth rate of new particles (GR). A moderately good linear correlation was also obtained between Dpgmax and GR, and only GR larger than 7.9 nm h -1 can lead to new particles growing with Dpgmax beyond 50 nm. Combining simultaneous measurements of the particle number size distributions and cloud condensation nuclei (CCN) at different super saturations (SS), we indeed observed a clear increase in CCN when the Dpg of new particles exceeded 50 nm at SS=0.4%. However, it was not the case for SS=0.2%. Consistent with previous studies in 30 continental atmosphere, our results implied that 50 nm can be used as the threshold for new particles to be activated as CCN in the marine atmosphere. Moreover, the κ decreased from 0.4 to 0.1 during the growth period of new particles, implying that Atmos. Chem. Phys. Discuss., https://doi

Increased new particle yields with largely decreased probability of survival to CCN size at the summit of Mt. Tai under reduced SO&lt;sub&gt;2&lt;/sub&gt; emissions

“…The fitted equation was highly consistent with those derived for urban and marine atmospheres (Man et al, 2015;Zhu et al, , 2019Ma et al, 2020). The strong linear relationship between the FR and NMINP suggested that H2SO4 vapor was sufficient for nucleation, and the NPF intensity was very likely determined by the abundance of organic vapors available for participating in nucleation.…”

“…The increase in the NMINP should enhance the contribution of NPF events to the ambient particle number concentration, but the NMINP at Mt. Tai before 2015 was only approximately ¼-½ of our previous observations in urban and marine atmospheres (Zhu et al, , 2019.…”

“…Dpg represents the geometric median diameter of new particles and was fitted by a multi log-normal distribution function (Whitby, 1978;Zhu et al, 2014Zhu et al, , 2019Man et al, 2015). Varying size ceilings occurred during the growth of newly formed particles, and the maximum size of Dpg was defined as Dpgmax (Zhu et al, 2019).…”

Tropospheric aerosol hygroscopicity measurements in China

“…Qingdao (Li et al, 2015a), Shanghai (Leng et al, 2013;Leng et al, 2014), Guangzhou (Duan et al, 2017;Duan et al, 2018) and Mt. Huang (Fang et al, 2016), as well as over marginal seas of China (Zhu et al, 2019; and northwestern Pacific (Wang et al, 2019a;Zhu et al, 2019). As these studies did not carry out size-resolved measurements and thus did not report critical diameters or κ, they are not further discussed herein.…”

Mapping gaseous amines, ammonia, and their particulate counterparts in marine atmospheres of China’s marginal seas: Part 1 – Differentiating marine emission from continental transport

“…When released into the environment, they can be degraded by bacteria to trimethylamine (TMA) and then dimethylamine (DMA) or methylamines (MA) (Lidbury et al, 2015a;Lidbury et al, 2015b). Gaseous DMA, TMA, and MA may play an important role in the formation of secondary particles in the atmosphere by nucleation (Almeida et al, 2013;Chen et al, 2016;Yao et al, 2018;Zhu et al, 2019). However, measuring gaseous amines in real-time simultaneously to their particulate counterparts in the marine atmosphere over the ocean remains challenging, although this is not the case in the continental atmosphere (VandenBoer et al, 2011).…”