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Map of the North China Plain. The observational site is marked as a red point. Urban areas are marked in yellow. The green line denotes the contour line of 500 m a.s.l., which can be considered as the natural boundary of the NCP.
Source publication
The aim of this investigation was to obtain a better understanding of the
variability of the cloud condensation nuclei (CCN) activity during new
particle formation (NPF) events in an anthropogenically polluted atmosphere
of the North China Plain (NCP). We investigated the size-resolved activation
ratio as well as particle number size distribution,...
Contexts in source publication
Context 1
... 9 July to 8 August in 2013, microphysical and op- tical properties of aerosol particles over the size range from 10 nm to 10 µm were measured at Xianghe station (39.75 • N, 116.96 • E; 36 m a.s.l.), a regional atmospheric observatory in the NCP about 50 km southeast from Beijing and 70 km west from Tianjin (Fig. 1). The observatory is located close to a small village and about 5 km west of Xianghe city cen- ter. The surroundings are farmland and residential areas. The measurements can be assumed to be representative of the re- gional background aerosol of the north NCP during daytime (09:00-18:00 LT). From time to time, an influence of local ...
Context 2
... this study, we simply define the particles with κ > 0.1 as hygroscopic mode particles, and the rest as nearly hydropho- bic mode particles. More details about this measurement and data processing can be found in Zhang et al. (2016). As a reference, a comparison of κ derived with DMA-CCNC mea- surement and HTDMA measurement is shown in Fig. S1 in ...
Similar publications
Light detection and ranging (lidar) measurements have been widely used to profile the ambient aerosol extinction coefficient (σext). The particle extinction-to-backscatter ratio (lidar ratio, LR), which strongly depends on the aerosol dry particle number size distribution (PNSD) and aerosol hygroscopicity, is introduced to retrieve the σext profile...
Light detection and ranging (lidar) measurements have been widely used to profile ambient aerosol extinction coefficient (σext). Particle extinction-to-backscatter ratio (lidar ratio, LR), which highly depends on aerosol dry particle number size distribution (PNSD) and aerosol hygroscopicity, is introduced to retrieve the σext profile from elastic-...
Citations
... This means that the effect of hygroscopicity on CCN surpasses the influence on particle size at low supersaturations. This conclusion is consistent with the observation conducted by Ma et al. (2016) in the North China Plain in 2013, which suggested that along with the decrease in SS, the particles that can be activated into CCN are more sensitive to changes in particle hygroscopicity. Similarly, based on observational data in northern China in summer, Wang et al. (2023) found that CN in 2020 is lower than that in 2014 due to particulate pollution control; however, the particles become more easily activated, attributable to the larger extent of the decrease in organic matter compared to inorganics, leading to enhanced particle hygroscopicity and more conduciveness to activation. ...
New particle formation (NPF) and subsequent particle growth are important sources of condensation nuclei (CN) and cloud condensation nuclei (CCN). While many observations have shown positive contributions of NPF to CCN at low supersaturation, negative NPF contributions were often simulated in polluted environments. Using the observations in a coastal city of Qingdao, Beijing, and Gucheng in north China, we thoroughly evaluate the simulated number concentrations of CN and CCN using an NPF-explicit parameterization embedded in the WRF-Chem model. For CN, the initial simulation shows large biases of particle number concentrations at 10–40 and 40–100 nm. By adjusting the process of gas–particle partitioning, including the mass accommodation coefficient (MAC) of sulfuric acid, the phase changes in primary organic aerosol emissions, and the condensational amount of nitric acid, the improvement of the particle growth process yields substantially reduced overestimation of CN. Regarding CCN, secondary organic aerosol (SOA) formed from the oxidation of semi-volatile and intermediate-volatility organic compounds (S/IVOCs) is called SI-SOA, the yield of which is an important contributor. At default settings, the SI-SOA yield is too high without considering the differences in precursor oxidation rates. Lowering the SI-SOA yield under linear H2SO4 nucleation scheme results in much-improved CCN simulations compared to observations. On the basis of the bias-corrected model, we find substantially positive contributions of NPF to CCN at low supersaturation (∼ 0.2 %) over broad areas of China, primarily due to competing effects of increasing particle hygroscopicity, a result of reductions in SI-SOA amount, surpassing that of particle size decreases. The bias-corrected model is robustly applicable to other schemes, such as the quadratic H2SO4 nucleation scheme, in terms of CN and CCN, though the dependence of CCN on SI-SOA yield is diminished likely due to changes in particle composition. This study highlights potentially much larger NPF contributions to CCN on a regional and even global basis.
... A modified algorithm based on Hagen and Alofs (1983) and Deng et al. (2011) was used to correct the influence of multiple-charge particles on SPAR. Details about the system are described in Ma et al. (2016) and Tao et al. (2021). The SSs of CCNC were calibrated with monodisperse ammonium sulfate particles (Rose et al., 2008) both before and after the campaign and details about the calibration can be found in Section S1 in Supporting Information S1. ...
Plain Language Summary
Accurate Cloud Condensation Nuclei (CCN) predictions in climate and regional models are crucial for the assessment of climate effects of aerosol‐cloud interactions. Direct measurements of CCN activity, varied by aerosol size, hygroscopicity, and supersaturation, are important for model verifications and improvements. The commercial continuous‐flow streamwise thermal‐gradient CCN counter (CCNC) is widely used in CCN activity measurements. We found that the droplet growth in the CCNC is kinetically limited under low supersaturations (<0.14%), thus not reaching the theoretical critical activation diameter, which significantly affect CCN identification. Kinetic model results revealed that the wet diameter thresholds of CCN identification that took the kinetic limitations of droplet growth into account were independent of dry aerosol size and hygroscopicity thus could be directly used as new criteria for CCN identification. Neglecting the kinetic growth limitation in CCN identification would result in significant bias in CCN activity measurements and thus supersaturated aerosol hygroscopicity retrievals. Findings of this research have significant impacts on CCN activity measurements and supersaturated aerosol hygroscopicity investigations.
... Despite being one of the most polluted regions in China, the North China Plain (NCP) has reported a high frequency of NPF events, which further contribute to air pollution as well as CCN (Guo et al., 2014;Kulmala et al., 2021;Ma et al., 2016;Wu et al., 2008). There is a pressing need to quantitatively understand NPF from vertical insights, and this is of paramount importance from the point of view of clouds, especially under such high aerosol loading environment. ...
Plain Language Summary
New particle formation (NPF) is a worldwide phenomenon and is regarded as a major contributor to the global cloud condensation nuclei (CCN) as well as to air pollution. Given the vertically varied cloud distribution and the vital role of NPF in CCN, it is of great importance to understand the vertical structure of NPF. However, the overwhelming majority of NPF studies are based on near‐surface measurements. By conducting simultaneous observations at two different altitudes in the polluted North China Plain, our study demonstrated that there is an earlier and stronger NPF event in the upper air, especially on polluted days. It is revealed that vertical disparities in NPF are mainly attributed to the pronounced stratification of sulfur dioxide, ozone and particulate matter concentrations in the planetary boundary layer. The differences in NPF onset time together with formation and growth rate in vertical suggest potentially significant impacts on low clouds and particle pollution near the ground. This work shed new light on the vertical structure of NPF and thus their effects on climate change and air pollution.
... Besides, the MH mode shifted to a higher GF value with an increase in particle sizes, implying that larger particles were more aged with a higher fraction of inorganic salt (Fig. S7) and well separated from the freshly emitted counterparts. A similar phenomenal pattern was previously observed in the urban environment, including the PRD region (Hong et al., 2018;Cai et al., 2017;Jiang et al., 2016;Tan et al., 2013b), the North China Plain Ma et al., 2016), and other city regions around Mochida et al., 2006;Massling et al., 2005). Table 3 summarizes the N CCN , activation ratio (AR), D 50 , and κ CCN values at 0.1 %, 0.2 %, 0.4 %, 0.7 %, 0.9 %, and 1.0 % SS during the campaign. ...
Organic aerosol (OA) has a significant contribution to cloud formation and hence climate change. However, high uncertainties still exist in its
impact on global climate, owing to the varying physical properties affected by the complex formation and aging processes. In this study, the
hygroscopicity, volatility, cloud condensation nuclei (CCN) activity, and chemical composition of particles were measured using a series of online
instruments at a rural site in the Pearl River Delta (PRD) region of China in fall 2019. During the campaign, the average hygroscopicity of OA
(κOA) increased from 0.058 at 30 nm to 0.09 at 200 nm, suggesting a higher oxidation state of OA at larger particle
sizes, supported by a higher fraction of extremely low volatility OA (ELVOA) for larger size particles. Significantly different diurnal patterns of
κOA were observed between Aitken mode particles and accumulation mode particles. For Aitken mode particles (30–100 nm), the
κOA values showed daily minima (0.02–0.07) during daytime, while the accumulation mode exhibited a daytime peak
(∼ 0.09). Coincidently, a daytime peak was observed for both aged biomass burning organic aerosol (aBBOA) and less oxygenated organic aerosol
(LOOA) based on source apportionment, which was attributed to the aging processes and gas–particle partitioning through photochemical reactions. In
addition, the fraction of semi-volatile OA (SVOA) was higher at all measured sizes during daytime than during nighttime. These results indicate that
the formation of secondary OA (SOA) through gas–particle partitioning can generally occur at all diameters, while the aging processes of
pre-existing particles are more dominated in the accumulation mode. Furthermore, we found that applying a fixed κOA value (0.1) could
lead to an overestimation of the CCN number concentration (NCCN) up to 12 %–19 % at 0.1 %–0.7 % supersaturation (SS),
which was more obvious at higher SS during daytime. Better prediction of NCCN could be achieved by using size-resolved diurnal
κOA, which indicates that the size dependence and diurnal variations in κOA can strongly affect the NCCN at
different SS values. Our results highlight the need for accurately evaluating the atmospheric evolution of OA at different size ranges and their impact on
the physicochemical properties and hence climate effects.
... 37,38 For example, Lu et al. 39 showed S/ IVOCs emitted from sources such as diesel, gas-turbine engines have substantially higher SOA formation potential than traditionally well-studied VOCs such as monoaromatics, whereas S/IVOC and traditional VOC emissions from gasoline engine contribute similar amount to SOA formation. Similarly, while some box 22,40 and 3-D 41 modeling work show important S/IVOC contributions to SOA formation in urban environments, other models 42−44 found less. In situ OFR-based studies of the SOA formation potential in urban regions, coupled with direct measurements of both reactive VOC and S/IVOC precursors, may provide new insight on this issue. ...
... A detailed description of the method was given by Kalkavouras et al. (2019). The enhancement factor, denoted as E_N CCN , was calculated as the ratio of N CCN_after /N CCN_prior (Laaksonen et al., 2005;Ma et al., 2016;Peng et al., 2014;Z. B. Wang et al., 2013;Wu et al., 2015;Zhang et al., 2019). ...
The new particle formation (NPF) effect on cloud condensation nuclei (CCN) differs from region to region and remains highly uncertain. Here, we re‐evaluate the NPF‐initiated enhancements in CCN number concentrations (E_NCCN) by compiling results from 35 field sites worldwide and five global models. We show the E_NCCN at sites close to the anthropogenic sources are more than 2‐fold as large as that at remote sites with supersaturations of 0.1%–1.0%. The enhancements anti‐correlate with the time scales for the new particles to grow to CCN size, which are 5–10 and 20–30 hr at polluted and remote sites, respectively. We further reveal that under polluted environments the condensational growth of new particles may be accelerated, leading to larger E_NCCN. The models fail to simulate the E_NCCN in polluted regions. Our study highlights the importance of parameterizing the time scale of NPF to affect CCN differently for remote and polluted regions in models.
... These nucleated particles subsequently grow through coagulation or condensation processes to CCN-relevant sizes or act as CCN in convective clouds (Fan et al., 2013;Li et al., 2010). In reality, field studies have shown that these fine particles produced from NPF can subsequently result in an enhancement in N CCN at cloud-relevant supersaturation (Kalkavouras et al., 2017;Peng et al., 2014;Wu et al., 2015;Ma et al., 2016;Zhang et al., 2019). It was estimated that up to 80 % of CCN number concentration (N CCN ) is from the nucleation process in urban Beijing . ...
... The increment of N CCN or N d by the NPF ( N CCN or N d ) is usually quantified by comparing the N CCN or N d prior to and after the NPF event (Peng et al., 2014;Wu et al., 2015;Ma et al., 2016;Ren et al., 2018;Zhang et al., 2019;Fan et al., 2020). In this study, the N CCN or N d prior to the NPF event was determined as a 2 h average of N CCN or N d before the burst of newly formed nucleated particles. ...
The effect of new particle formation (NPF) on cloud condensation nuclei (CCN)
varies widely in diverse environments. CCN or cloud droplets from NPF
sources remain highly uncertain in the urban atmosphere; they are greatly
affected by the high background aerosols and frequent local emissions. In
this study, we quantified the effect of NPF on cloud droplet number
concentration (CDNC, or Nd) at typical updraft velocities (V) in clouds
based on field observations on 25 May–18 June 2017 in urban Beijing. We
show that NPF increases the Nd by 32 %–40 % at V=0.3–3 m s−1
during the studied period. The Nd is reduced by 11.8 ± 5.0 % at
V=3 m s−1 and 19.0 ± 4.5 % at V=0.3 m s−1 compared to
that calculated from constant supersaturations due to the water vapor
competition effect, which suppresses the cloud droplet formation by decreasing
the environmental maximum supersaturation (Smax). The effect of water
vapor competition becomes smaller at larger V that can provide more
sufficient water vapor. However, under extremely high aerosol particle
number concentrations, the effect of water vapor competition becomes more
pronounced. As a result, although a larger increase of CCN-sized particles by
NPF events is derived on clean NPF days when the number concentration of
preexisting background aerosol particles is very low, no large discrepancy
is presented in the enhancement of Nd by NPF between clean and
polluted NPF days. We finally reveal a considerable impact of the primary
sources on the evaluation of the contribution of NPF to CCN number
concentration (NCCN) and Nd
based on a case study. Our study highlights the importance of full
consideration of both the environmental meteorological conditions and
multiple sources (i.e., secondary and primary) to evaluate the effect of NPF on
clouds and the associated climate effects in polluted regions.
... The air borne coarse mode (> 2 µm) aerosol concentration over the polluted Indo Gangetic Plains (IGP) was < 2 cm −3 (Varghese et al. 2019), and < 1 cm −3 over Pune, another station on the leeward side of WG (Padmakumari et al. 2013). On the other hand, nucleation mode (< 0.01 µm) particles require very high supersaturations to become CCN (Varghese et al. 2020;Zhang et al. 2019;Ma et al. 2016). Hence, the observed difference between the CCN measurements and the PCASP measurements can be safely assumed to be the Aitken mode number concentration. ...
In situ measurements of aerosol particle chemistry and cloud microphysics made during the Cloud–Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) in 2015 over the Western Ghats and its rain shadow region are presented in this study. The high ratio of cloud condensation nuclei (CCN) to large sized aerosol (above 0.1 µm) concentrations indicates Aitken mode aerosols as the major contributor towards the observed CCN. Morphology and chemical composition of airborne aerosol samples collected from different altitudes and the warm cloud layers indicated distinct particle chemistry on the dry and wet days. The majority of the particles sampled were heterogeneous and internally mixed with two or more aerosol species indicating multiple sources and atmospheric aging, even during the wet days. Si-rich particles (up to 73%) were the dominant species in samples collected during dry days when the shallow clouds with narrow drop size distribution were observed. A higher concentration of Na-rich particles (up to 50%) was observed on wet days when the clouds were majorly multiple layers of stratus, which had broader cloud droplet spectra. Internally mixed carbonaceous and iron/cobalt-rich aerosols from local pollution sources were found on both wet and dry days suggesting boundary layer venting of aerosols. Large droplets were observed near the cloud base over the Western Ghats compared to those formed over the rain shadow region.
... Alternatively, it can be predicted from several approaches including campaign averaged critical diameter (D 50 ) or activation curve in combination with real time measured particle number size distribution (PNSD) which provide reasonable CCN approximation (M. Ma et al., 2016;Ovadnevaite et al., 2017). A fraction of newly formed particles during NPF events will eventually grow to a diameter above 50 nm which can then be activated as CCN. ...
... Hence, condensable species during particle growth affect chemical composition of the particles which can significantly modify particle hygroscopicity and further affect CCN activity. Particles that are formed and grow in a sulfur-rich environment usually have high hygroscopicity, while particles driven by organic vapors during their formation and growth can lead to low hygroscopicity (Ma et al., 2016;Wu et al., 2013). Previous studies found that chemical composition of nucleated particles depends on the characteristics of atmospheric environment (Boy et al., 2005;Stolzenburg et al., 2005;Yue et al., 2010). ...
... High occurring frequencies of NPF events were attributed to high concentrations of condensable gaseous precursors in Chinese urban cities (Wu et al., 2007). To date, most measurements were carried out under polluted atmospheric environments, such as megacities in China, to investigate the variation of CCN activity, including N CCN and D 50 , during NPF events (Leng et al., 2014;Ma et al., 2016). The growth rate was found to be the controlling factor that facilitated conversion of ultrafine particles formed in NPF to CCN in Shanghai, leading to significant increases of the CCN concentrations (N CCN ) under high SS ratios (Leng et al., 2014). ...
A 1‐month field campaign (May 29–June 29, 2018) was conducted at a mountain site (862 m above sea level) on the Wudang Mountains in China. The particle number size distribution (3–400 nm), size‐resolved cloud condensation nuclei (CCN, at 0.2% and 0.8% SS), and nonrefractory PM1 chemical composition were measured, respectively. The occurrence of the three chosen new particle formation (NPF) events (June 4, 7, and 11) was facilitated by southwest or west winds with a speed of about 3–4 m s⁻¹. The hygroscopicity parameter (κ) value of newly grown particles varied in a wide range (0.25–0.8) during the events, leading to large uncertainties (−98% to 38%) on the NCCN prediction compared to the campaign. During growth of the newly formed particles for the three events, condensation of sulfuric acid vapor accounts for 14%–42%, 2%–8%, and 3%–9%, respectively, indicating that organic vapors may play an important role in particle growth. For plume‐type events with rapid growth, the observed high CCN activity (i.e., June 7 event) may be explained by the contribution of amines and depression of surface tension in the presence of organic surfactants during particle growth. Our study demonstrates that the contribution of NPF to CCN concentration is modulated by many key factors including growth rate, hygroscopicity, concentrations of new particles and preexisting particles, and variation of those factors from one event to another leads to large uncertainties on the CCN prediction.
... increase of the N CCN was observed during NPF events in Shanghai (Leng et al., 2014). The results from Ma et al. (2016) showed that the N CCN was significantly impacted by the hygroscopicity of newly formed particles during NPF events in the North China Plain (NCP). Yu et al. (2014) reported an average factor of 4.7 increase of the N CCN during NPF events from growth of new particles to the CCN sizes in Ozark forest. ...
The contribution of new particle formation (NPF) to cloud condensation
nuclei (CCN) number concentration (NCCN) varies largely under different
environments and depends on several key factors such as formation rate (J),
growth rate (GR), distribution of preexisting particles, and properties of
new particles during NPF events. This study investigates the contribution of
NPF to the NCCN and its controlling factors based on measurements
conducted at the Heshan supersite, in the Pearl River Delta (PRD) region of
China during fall 2019. The size-resolved cloud condensation nuclei
activity and size-resolved particle hygroscopicity were measured by a cloud
condensation nuclei counter (CCNc) and a hygroscopic tandem differential
mobility analyzer (HTDMA), respectively, along with a scanning mobility
particle sizer (SMPS) and a diethylene glycol scanning mobility particle
sizer (DEG-SMPS) for particle number size distribution (PNSD). A typical NPF
event on 29 October was chosen to investigate the contribution of the
NPF to NCCN under several supersaturation (SS) ratios. Two particle
properties (hygroscopicity and surface tension) affect CCN activation with
the latter being more important in terms of the CCN concentration
(NCCN). A lower value of surface tension (i.e., 0.06 N m−1) than the
pure-water assumption (0.073 N m−1) could increase the NCCN at
SS = 1.0 % by about 20 % during the nonevent period and by about 40 % during the event. In addition, an earlier peak time corresponding to a lower
critical diameter (D50) was also observed. The results show that high
formation rate, growth rate, and low background particle concentration lead
to high number concentrations of newly formed particles. The high growth
rate was found to have the most significant impact on the NCCN, which
can be attributed to the fact that a higher growth rate can grow particles
to the CCN size in a shorter time before they are scavenged by preexisting
particles. Two other NPF events (an event on 18 October in this
campaign and an event on 12 December 2014 in Panyu) were chosen to
perform sensitivity tests under different scenarios (growth rate, formation
rate, and background particle concentration). The calculated NCCN at
SS = 1.0 % on 12 December 2014 was significantly lower than that
from the other two events. The event on 12 December was re-simulated
using the growth rate taken from the event on 18 October which
resulted in similar CCN concentrations between the two events (12 December and 18 October), implying that the growth rate is the major
impact factor for CCN activation. Our results highlight the importance of
growth rate and surface tension when evaluating the contribution of NPF to
the NCCN.
