New particle formation infrequently observed in Himalayan foothills – why?

Neitola, Kimmo; Asmi, Eija; Komppula, Mika; Hyvärinen, Antti; Raatikainen, Tomi; Panwar, T. S.; Sharma, Ved P.; Lihavainen, Heikki

doi:10.5194/acp-11-8447-2011

Cited by 57 publications

(53 citation statements)

References 64 publications

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“…GR values of similar magnitudes have been reported in the literature from long-term measurements from various high-altitude sites (e.g. Venzac et al, 2008;Boulon et al, 2010;Neitola et al, 2011;Yli-Juuti et al, 2011).…”

supporting

confidence: 64%

The formation and growth of ultrafine particles in two contrasting environments: a case study

Babu

Moorthy

2014

Ann. Geophys.

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Abstract. Formation of ultrafine particles and their subsequent growth have been examined during new particle formation (NPF) events in two contrasting environments under varying ambient conditions, one for a tropical semiurban coastal station, Trivandrum, and the other for a highaltitude free-tropospheric Himalayan location, Hanle. At Trivandrum, NPF bursts took place in the late evening/night hours, whereas at Hanle the burst was a daytime event. During the nucleation period, the total number concentration reached levels as high as ∼ 15 900 cm −3 at Trivandrum, whereas at Hanle, the total number concentration was ∼ 2700 cm −3 , indicating the abundant availability of precursors at Trivandrum and the pristine nature of Hanle. A sharp decrease was associated with NPF for the geometric mean diameter of the size distribution, and a large increase in the concentration of the particles in the nucleation regime (D p < 25 nm). Once formed, these (secondary) aerosols grew from nucleation (diameter D p < 25 nm) to Aitken (25 ≤ D p ≤ 100 nm) regime and beyond, to the accumulation size regimes (100 ≤ D p ≤ 1000 nm), with varying growth rates (GR) for the different size regimes at both the locations. A more rapid growth ∼ 50 nm h −1 was observed at Trivandrum, in contrast to Hanle where the growth rate ranged from 0.1 to 20 nm h −1 for the transformation from the nucleation to accumulation -a size regime that can potentially act as cloud condensation nuclei (CCN). The faster coagulation led to lifetimes of < 1 h for nucleation mode particles.

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confidence: 64%

The formation and growth of ultrafine particles in two contrasting environments: a case study

Babu

Moorthy

2014

Ann. Geophys.

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“…Also the reduced vertical mixing of the lower atmosphere at lower temperature during winter might cause the depletion of the precursor gases and increase the condensation sink. A high background of larger particulate matter also acts as a condensation sink for the nucleating vapours and initially formed nm-sized particles (Neitola et al, 2011). We observed higher fine mode aerosol (PM 2.5 ) concentration than coarse mode (PM of diameter larger than 2.5 microns) aerosol over the same study location in the year of 2005 (Chatterjee et al, 2010) and 2008 (Chatterjee et al, 2012) throughout the entire dry season.…”

Section: Factors Controlling Ultrafine Aerosol Formationmentioning

confidence: 52%

Atmospheric Fine Mode Particulates at Eastern Himalaya, India: Role of Meteorology, Long-Range Transport and Local Anthropogenic Sources

Adak

Chatterjee

Singh

et al. 2014

Aerosol Air Qual. Res.

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A study on atmospheric fine (less than 2.0 µm) particulate matter was performed for the first time over the eastern Himalayas in India in order to investigate the formation and sources in two different seasons, pre-monsoon (Mar-May) and winter (Dec-Feb), for three consecutive years, 2008, 2009 and 2010. Fine mode aerosols were further segregated into three modes: ultrafine (less than 0.32 µm), superfine (0.32-1.0 µm) and fine (1.0-2.0 µm). The study was carried out at a high altitude hill station Darjeeling (2200 m asl) in the eastern Himalayas, India, using an aerosol spectrometer (GRIMM) to measure aerosol number concentrations. It was found that the ultrafine and superfine aerosol (less than 1.0 µm) concentrations were higher in the pre-monsoon period compared to winter, whereas the concentrations of fine mode aerosols were comparable during these two seasons. Meteorological conditions like sunny/non-cloudy days with higher radiative fluxes and lower humidity favored the formation of ultrafine aerosols from their precursor gases, and the initiation of this formation were observed during 0900-1000 hours LT. Superfine aerosols were mainly found to be aerosols transported from long distances during the pre-monsoon period, and showed peak levels during late morning till late afternoon. In contrast, higher concentrations were seen at night in winter. The fine mode aerosols were mainly locally generated anthropogenic aerosols, mostly emitted from vehicular sources during the pre-monsoon period, and from biomass burning during winter, with sharp diurnal peaks during morning and evening. The long-term study on size segregated aerosol concentrations carried out in this work is of considerable importance, and can be helpful for the validation of several regional and global aerosol models, and for other climate related studies that focus on the Himalayan region.

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“…In Puy de Dôme mount the maximum frequency of events was found during early spring and early autumn (Boulon et al, 2011). In the Nepal Himalayas these events were observed in the monsoon (July-September) and post-monsoon (October-December) seasons (∼ 50 %), whereas in the Indian Himalayas they occur in spring (∼ 80 % from March to June; Neitola et al, 2011). In the upper plateau of East Antarctica, Järvinen et al (2013) reported that these events take place more often during summer.…”

Section: Classification Of Episodesmentioning

confidence: 99%

“…in the Nepal Himalayas (∼ 43 %; Venzac et al, 2008) and in Puy de Dôme (∼ 38 %; Manninen et al, 2010), but higher than those observed at 2180 m a.s.l. in the Indian Himalayas (∼ 11 %; Neitola et al, 2011) and at 3580 m a.s.l. in the Swiss Alps (∼ 20 %; Jungfraujoch; Boulon et al, 2010;Manninen et al, 2010).…”

Section: Classification Of Episodesmentioning

confidence: 99%

Climatology of new particle formation at Izaña mountain GAW observatory in the subtropical North Atlantic

et al. 2014

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Abstract. A climatology of new particle formation (NPF) events at high altitude in the subtropical North Atlantic is presented. A 4-year data set (June 2008-June 2012, which includes number size distributions (10-600 nm), reactive gases (SO 2 , NO x , and O 3 ), several components of solar radiation and meteorological parameters, measured at Izaña Global Atmosphere Watch (GAW) observatory (2373 m above sea level; Tenerife, Canary Islands) was analysed. NPF is associated with the transport of gaseous precursors from the boundary layer by orographic buoyant upward flows that perturb the low free troposphere during daytime. On average, 30 % of the days contained an NPF event. Mean values of the formation and growth rates during the study period were 0.46 cm −3 s −1 and 0.42 nm h −1 , correspondingly. There is a clearly marked NPF season (May-August), when these events account for 50-60 % of the days per month.Monthly mean values of the formation and growth rates exhibit higher values in this season, 0.49-0.92 cm −3 s −1 and 0.48-0.58 nm h −1 , respectively. During NPF events, SO 2 , UV radiation and upslope winds showed higher values than during non-events. The overall data set indicates that SO 2 plays a key role as precursor, although other species seem to contribute during some periods. Condensation of sulfuric acid vapour accounts for most of the measured particle growth during most of the year (∼ 70 %), except for some periods. In May, the highest mean growth rates (∼ 0.6 nm h −1 ) and the lowest contribution of sulfuric acid (∼ 13 %) were measured, suggesting a significant involvement of other condensing vapours. The SO 2 availability seems also to be the most influencing parameter in the year-to-year variability in the frequency of NPF events. The condensation sink showed similar features to other mountain sites, showing high values during NPF events. Summertime observations, when Izaña is within the Saharan Air Layer, suggest that dust particles may play a significant role acting as coagulation sink of freshly formed nucleation particles. The contribution of dust particles to the condensation sink of sulfuric acid vapours seems to be modest (∼ 8 % as average). Finally, we identified a set of NPF events in which two nucleation modes, which may evolve at different rates, occur simultaneously and for which further investigations are necessary.

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New particle formation infrequently observed in Himalayan foothills – why?

Cited by 57 publications

References 64 publications

The formation and growth of ultrafine particles in two contrasting environments: a case study

The formation and growth of ultrafine particles in two contrasting environments: a case study

Atmospheric Fine Mode Particulates at Eastern Himalaya, India: Role of Meteorology, Long-Range Transport and Local Anthropogenic Sources

Climatology of new particle formation at Izaña mountain GAW observatory in the subtropical North Atlantic

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