scholarly journals In situ observation of new particle formation (NPF) in the tropical tropopause layer of the 2017 Asian monsoon anticyclone – Part 2: NPF inside ice clouds

2021 ◽  
Vol 21 (17) ◽  
pp. 13455-13481 ◽  
Author(s):  
Ralf Weigel ◽  
Christoph Mahnke ◽  
Manuel Baumgartner ◽  
Martina Krämer ◽  
Peter Spichtinger ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Deep Convection ◽  
Particle Formation ◽  
In Situ Observation ◽  
New Particle Formation ◽  
Nucleation Mode ◽  
Ice Particles ◽  
Cloud Ice ◽  
The Impact

Abstract. From 27 July to 10 August 2017, the airborne StratoClim mission took place in Kathmandu, Nepal, where eight mission flights were conducted with the M-55 Geophysica up to altitudes of 20 km. New particle formation (NPF) was identified by the abundant presence of nucleation-mode aerosols, with particle diameters dp smaller than 15 nm, which were in-situ-detected by means of condensation nuclei (CN) counter techniques. NPF fields in clear skies as well as in the presence of cloud ice particles (dp > 3 µm) were encountered at upper troposphere–lowermost stratosphere (UTLS) levels and within the Asian monsoon anticyclone (AMA). NPF-generated nucleation-mode particles in elevated concentrations (Nnm) were frequently found together with cloud ice (in number concentrations Nice of up to 3 cm−3) at heights between ∼ 11 and 16 km. From a total measurement time of ∼ 22.5 h above 10 km altitude, in-cloud NPF was in sum detected over ∼ 1.3 h (∼ 50 % of all NPF records throughout StratoClim). Maximum Nnm of up to ∼ 11 000 cm−3 was detected coincidently with intermediate ice particle concentrations Nice of 0.05–0.1 cm−3 at comparatively moderate carbon monoxide (CO) contents of ∼ 90–100 nmol mol−1. Neither under clear-sky nor during in-cloud NPF do the highest Nnm concentrations correlate with the highest CO mixing ratios, suggesting that an elevated pollutant load is not a prerequisite for NPF. Under clear-air conditions, NPF with elevated Nnm (> 8000 cm−3) occurred slightly less often than within clouds. In the presence of cloud ice, NPF with Nnm between 1500–4000 cm−3 was observed about twice as often as under clear-air conditions. NPF was not found when ice water contents exceeded 1000 µmol mol−1 in very cold air (< 195 K) at tropopause levels. This indicates a reduction in NPF once deep convection is prevalent together with the presence of mainly liquid-origin ice particles. Within in situ cirrus near the cold point tropopause, recent NPF or intense events with mixing ration nnm larger than 5000 mg−1 were observed only in about 6 % of the in-cloud NPF data. In determining whether the cloud-internal NPF is attenuated or prevented by the microphysical properties of cloud elements, the integral radius (IR) of the ice cloud population turned out to be indicative. Neither the number of ice particles nor the free distance between the ice particles is clearly related to the NPF rate detected. While the increase in ice particles' mass per time dmdt is proportional to the IR and mainly due to the condensation of water vapour, additional condensation of NPF precursors proceeds at the expense of the NPF rate as the precursor's saturation ratio declines. Numerical simulations show the impact of the IR on the supersaturation of a condensable vapour, such as sulfuric acid, and furthermore illustrate that the IR of the cloud ice determines the effective limitation of NPF rates.

scholarly journals In situ observation of new particle formation (NPF) in the tropical tropopause layer of the 2017 Asian monsoon anticyclone – Part 1: Summary of StratoClim results

2021 ◽  
Vol 21 (15) ◽  
pp. 11689-11722
Author(s):  
Ralf Weigel ◽  
Christoph Mahnke ◽  
Manuel Baumgartner ◽  
Antonis Dragoneas ◽  
Bärbel Vogel ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
Particle Formation ◽  
In Situ Observation ◽  
Aerosol Layer ◽  
New Particle Formation ◽  
Tropical Tropopause Layer ◽  
Temperature Anomalies ◽  
Nucleation Mode ◽  
Tropical Tropopause

Abstract. During the monsoon season of the year 2017 the airborne StratoClim mission took place in Kathmandu, Nepal, with eight mission flights of the M-55 Geophysica in the upper troposphere–lower stratosphere (UTLS) of the Asian monsoon anticyclone (AMA) over northern India, Nepal, and Bangladesh. More than 100 events of new particle formation (NPF) were observed. In total, more than 2 h of flight time was spent under NPF conditions as indicated by the abundant presence of nucleation-mode aerosols, i.e. with particle diameters dp smaller than 15 nm, which were detected in situ by means of condensation nuclei counting techniques. Mixing ratios of nucleation-mode particles (nnm) of up to ∼ 50 000 mg−1 were measured at heights of 15–16 km (θ ≈ 370 K). NPF was most frequently observed at ∼ 12–16 km altitude (θ ≈ 355–380 K) and mainly below the tropopause. Resulting nnm remained elevated (∼ 300–2000 mg−1) up to altitudes of ∼ 17.5 km (θ ≈ 400 K), while under NPF conditions the fraction (f) of sub-micrometre-sized non-volatile residues (dp > 10 nm) remained below 50 %. At ∼ 12–14 km (θ ≈ 355–365 K) the minimum of f (< 15 %) was found, and underneath, the median f generally remains below 25 %. The persistence of particles at nucleation-mode sizes is limited to a few hours, mainly due to coagulation, as demonstrated by a numerical simulation. The frequency of NPF events observed during StratoClim 2017 underlines the importance of the AMA as a source region for UTLS aerosols and for the formation and maintenance of the Asian tropopause aerosol layer (ATAL). The observed abundance of NPF-produced nucleation-mode particles within the AMA is not unambiguously attributable to (a) specific source regions in the boundary layer (according to backward trajectory analyses), or (b) the direct supply with precursor material by convective updraught (from correlations of NPF with carbon monoxide), or (c) the recent release of NPF-capable material from the convective outflow (according to air mass transport times in the tropical tropopause layer, TTL). Temperature anomalies with ΔT of 2 K (peak-to-peak amplitude), as observed at a horizontal wavelength of ∼ 70–100 km during a level flight of several hours, match with NPF detections and represent an additional mechanism for local increases in supersaturation of the NPF precursors. Effective precursor supply and widely distributed temperature anomalies within the AMA can explain the higher frequency of intense NPF observed during StratoClim 2017 than all previous NPF detections with COPAS (COndensation PArticle counting System) at TTL levels over Brazil, northern Australia, or West Africa.

scholarly journals New particle formation inside ice clouds: In-situ observations in the tropical tropopause layer of the 2017 Asian Monsoon Anticyclone

2021 ◽  
Author(s):  
Ralf Weigel ◽  
Christoph Mahnke ◽  
Manuel Baumgartner ◽  
Martina Krämer ◽  
Peter Spichtinger ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Asian Monsoon ◽  
Particle Formation ◽  
New Particle Formation ◽  
Mixing Ratios ◽  
Microphysical Properties ◽  
Tropical Tropopause ◽  
Ice Particles ◽  
Cloud Ice

Abstract. From 27 July to 10 August 2017 the airborne StratoClim mission took place in Kathmandu, Nepal where eight mission flights were conducted with the M-55 Geophysica up to altitudes of 20 km. New Particle Formation (NPF) was identified by the abundant presence of ultrafine aerosols, with particle diameters dp smaller than 15 nm, which were in-situ detected by means of condensation nuclei counting techniques. NPF fields in clear-skies as well as in the presence of cloud ice particles (dp > 3 µm) were encountered at upper troposphere/lowermost stratosphere (UT/LS) levels and within the Asian Monsoon Anticyclone (AMA). NPF-generated ultrafine particles in elevated concentrations (Nuf) were frequently found together with cloud ice (in number concentrations Nice of up to 3 cm−3) at heights between ~ 11 km and 16 km. From a total measurement time of ~ 22.5 hours above 10 km altitude, in-cloud NPF was in sum detected over ~ 1.3 hours (~ 50 % of all NPF records throughout StratoClim). Maximum Nuf of up to ~ 11000 cm−3 were detected coincidently with intermediate ice particle concentrations Nice of 0.05–0.1 cm−3 at comparatively moderate carbon monoxide (CO) contents of ~ 90–100 nmol mol−1. Neither under clear-sky nor during in-cloud NPF do the highest Nuf concentrations correlate with the highest CO mixing ratios, suggesting that an elevated pollutant load is not a prerequisite for NPF. Under clear-air conditions, NPF with elevated Nuf (> 8000 cm−3) occurred slightly less often than within clouds. In the presence of cloud ice, NPF with Nuf between 1500–4000 cm−3 were observed about twice as often as under clear air conditions. When ice water contents exceeded 1000 µmol mol−1 in very cold air ( 5000 mg−1) were rarely observed (~ 6 % of in-cloud NPF data). For specifying the constraining mechanisms for NPF possibly imposed by the microphysical properties of the cloud elements, the integral radius (IR) of the ice cloud population was identified as the most practicable indicator. Neither of both, the number of ice particles or the free distance between the ice particles, is clearly related to the NPF-rate detected. The results of a numerical simulation indicates how the IR affects the supersaturation of a condensable vapour, such as sulphuric acid, and that IR determines the effective limitation of NPF rates due to cloud ice.

scholarly journals In-Situ observation of New Particle Formation in the upper troposphere/lower stratosphere of the Asian Monsoon Anticyclone

2020 ◽  
Author(s):  
Ralf Weigel ◽  
Christoph Mahnke ◽  
Manuel Baumgartner ◽  
Antonis Dragoneas ◽  
Bärbel Vogel ◽  
...  
Keyword(s):  
Ultrafine Particles ◽  
Asian Monsoon ◽  
Lower Stratosphere ◽  
Monsoon Season ◽  
Particle Formation ◽  
In Situ Observation ◽  
New Particle Formation ◽  
Upper Troposphere ◽  
Mixing Ratios

Abstract. During the monsoon season of the year 2017 the airborne StratoClim mission took place in Kathmandu, Nepal with eight mission flights of the M-55 Geophysica in the upper troposphere/lower stratosphere (UT/LS) of the Asian Monsoon Anticyclone (AMA) over northern India, Nepal and Bangladesh. More than hundred events of New Particle Formation (NPF) were observed. In total, more than two hours of flight time were spent under NPF conditions as indicated by the abundant presence of ultrafine aerosols, i.e. with particle diameters dp smaller than 15 nm, which were in-situ detected by means of condensation nuclei counting techniques. Mixing ratios of ultrafine particles (nuf) of up to ~ 50000 mg−1 were measured at heights of 15–16 km (θ ≈ 370 K). NPF was most frequently observed at ~ 12–16 km altitude (θ ≈ 355–380 K) and mainly below the tropopause , but nuf remained elevated (~ 300–2000 mg−1) up to altitudes of ~ 17.5 km (θ ≈ 400 K) while under NPF conditions the fraction (f) of submicrometre-sized non-volatile particle residues (dp > 10 nm) remained below 50 %. At ~ 12–14 km (θ ≈ 355–365 K) the minimum of f (

scholarly journals Characterization of satellite based proxies for estimating nucleation mode particles over South Africa

2014 ◽  
Vol 14 (18) ◽  
pp. 25825-25867
Author(s):  
A.-M. Sundström ◽  
A. Nikandrova ◽  
K. Atlaskina ◽  
T. Nieminen ◽  
V. Vakkari ◽  
...  
Keyword(s):  
South Africa ◽  
Industrial Area ◽  
Particle Formation ◽  
Point Sources ◽  
New Particle Formation ◽  
Factors Affecting ◽  
Nucleation Mode ◽  
Sink Term ◽  
Major Factors

Abstract. In this work satellite observations from the NASA's A-Train constellation were used to derive the values of primary emission and regional nucleation proxies over South Africa to estimate the potential for new particle formation. As derived in Kulmala et al. (2011), the satellite based proxies consist of source terms (NO2, SO2 and UV-B radiation), and a sink term describing the pre-existing aerosols. The first goal of this work was to study in detail the use of satellite aerosol optical depth (AOD) as a substitute to the in situ based condensation sink (CS). One of the major factors affecting the agreement of CS and AOD was the elevated aerosol layers that increased the value of column integrated AOD but not affected the in situ CS. However, when the AOD in the proxy sink was replaced by an estimate from linear bivariate fit between AOD and CS, the agreement with the actual nucleation mode number concentration improved somewhat. The second goal of the work was to estimate how well the satellite based proxies can predict the potential for new particle formation. For each proxy the highest potential for new particle formation were observed over the Highveld industrial area, where the emissions were high but the sink due to pre-existing aerosols was relatively low. Best agreement between the satellite and in situ based proxies were obtained for NO2/AOD and UV-B/AOD2, whereas proxies including SO2 in the source term had lower correlation. Even though the OMI SO2 boundary layer product showed reasonable spatial pattern and detected the major sources over the study area, some of the known minor point sources were not detected. When defining the satellite proxies only for days when new particle formation event was observed, it was seen that for all the satellite based proxies the event day medians were higher than the entire measurement period median.

scholarly journals In situ observations of new particle formation in the tropical upper troposphere: the role of clouds and the nucleation mechanism

2011 ◽  
Vol 11 (18) ◽  
pp. 9983-10010 ◽  
Author(s):  
R. Weigel ◽  
S. Borrmann ◽  
J. Kazil ◽  
A. Minikin ◽  
A. Stohl ◽  
...  
Keyword(s):  
South America ◽  
West Africa ◽  
Central America ◽  
Particle Formation ◽  
Tropical Convection ◽  
New Particle Formation ◽  
Upper Troposphere ◽  
Nucleation Mode ◽  
In Situ Observations

Abstract. New particle formation (NPF), which generates nucleation mode aerosol, was observed in the tropical Upper Troposphere (UT) and Tropical Tropopause Layer (TTL) by in situ airborne measurements over South America (January–March 2005), Australia (November–December 2005), West Africa (August 2006) and Central America (2004–2007). Particularly intense NPF was found at the bottom of the TTL. Measurements with a set of condensation particle counters (CPCs) with different dp50 (50% lower size detection efficiency diameter or "cut-off diameter") were conducted on board the M-55 Geophysica in the altitude range of 12.0–20.5 km and on board the DLR Falcon-20 at up to 11.5 km altitude. On board the NASA WB-57F size distributions were measured over Central America in the 4 to 1000 nm diameter range with a system of nucleation mode aerosol spectrometers. Nucleation mode particle concentrations (NNM) were derived from these measurements which allow for identifying many NPF events with NNM in the range of thousands of particles per cm3. Over Australia and West Africa, we identified NPF in the outflow of tropical convection, in particular of a Mesoscale Convective System (MCS). Newly formed particles with NNM > 1000 cm−3 were found to coexist with ice cloud particles (dp > 2 μm) as long as cloud particle concentrations remained below 2 cm−3. The occurrence of NPF within the upper troposphere and the TTL was generally confined within 340 K to 380 K potential temperature, but NPF was of particular strength between 350 K and 370 K (i.e. ~1–4 km below the cold point tropopause). Analyses of the aerosol volatility (at 250 °C) show that in the TTL on average 75–90% of the particles were volatile, compared to typically only 50% in the extra-tropical UT, indicative for the particles to mainly consist of H2SO4-H2O and possibly organic compounds. Along two flight segments over Central and South America (24 February 2005 and 7 August 2006, at 12.5 km altitude) in cloud free air, above thin cirrus, particularly high NNM were observed. Recent lifting had influenced the probed air masses, and NNM reached up to 16 000 particles cm−3 (ambient concentration). A sensitivity study using an aerosol model, which includes neutral and ion induced nucleation processes, simulates NNM in reasonable agreement with the in situ observations of clear-air NPF. Based on new, stringent multi-CPC criteria, our measurements corroborate the hypothesis that the tropical UT and the TTL are regions supplying freshly nucleated particles. Our findings narrow the altitude of the main source region to the bottom TTL, i.e. to the level of main tropical convection outflow, and, by means of measurements of carbon monoxide, they indicate the importance of anthropogenic emissions in NPF. After growth and/or coalescence the nucleation mode particles may act as cloud condensation nuclei in the tropical UT, or, upon ascent into the stratosphere, contribute to maintain the stratospheric background aerosol.

scholarly journals Horizontally Oriented Plates in Clouds

2004 ◽  
Vol 61 (23) ◽  
pp. 2888-2898 ◽  
Author(s):  
François-Marie Bréon ◽  
Bérengère Dubrulle
Keyword(s):  
Atmospheric Turbulence ◽  
Tilt Angle ◽  
Signal Amplitude ◽  
In Situ Observation ◽  
Horizontal Plate ◽  
Specular Reflectance ◽  
Aerodynamic Model ◽  
The Earth ◽  
The Impact

Abstract Horizontally oriented plates in clouds generate a sharp specular reflectance signal in the glint direction, often referred to as “subsun.” This signal (amplitude and width) may be used to analyze the relative area fraction of oriented plates in the cloud-top layer and their characteristic tilt angle to the horizontal. Use is made of spaceborne measurements from the Polarization and Directionality of the Earth Reflectances (POLDER) instrument to provide a statistical analysis of these parameters. More than half of the clouds show a detectable maximum reflectance in the glint direction, although this maximum may be rather faint. The typical effective fraction (area weighted) of oriented plates in clouds lies between 10−3 and 10−2. For those oriented plates, the characteristic tilt angle is less than 1° in most cases. These low fractions imply that the impact of oriented plates on the cloud albedo is insignificant. The largest proportion of clouds with horizontally oriented plates is found in the range 500– 700 hPa, in agreement with typical in situ observation of plates in clouds. A simple aerodynamic model is proposed that accounts for the orienting torque of the flow as the plate falls under its own gravity and the disorienting effects of Brownian motion and atmospheric turbulence. The model indicates that the horizontal plate diameters are in the range 0.1 to a few millimeters. For such sizes, Brownian forces have a negligible impact on the plate orientation. On the other hand, typical levels of atmospheric turbulence lead to tilt angles that are similar to those estimated from the glint observation.

scholarly journals CCN production by new particle formation in the free troposphere

2017 ◽  
Vol 17 (2) ◽  
pp. 1529-1541 ◽  
Author(s):  
Clémence Rose ◽  
Karine Sellegri ◽  
Isabel Moreno ◽  
Fernando Velarde ◽  
Michel Ramonet ◽  
...  
Keyword(s):  
Particle Number ◽  
Particle Growth ◽  
Particle Formation ◽  
Number Concentration ◽  
Particle Number Concentration ◽  
Free Troposphere ◽  
New Particle Formation ◽  
Data Set ◽  
Radiative Processes ◽  
The Impact

Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ∼ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between 1 January and 31 December 2012, we found that 61 % of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 53 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud-related radiative processes.

An Overview of Maritime Transportation Dynamics-Mobilization and Livelihood in Galápagos Islands

2021 ◽  
pp. 52-90
Author(s):  
María Belén Arteaga-Custode ◽  
Claudia Fernanda Betancourt-Ruiz ◽  
María Serena López-Donoso ◽  
Sophia Veronique Nieto-Vasco ◽  
Carolina Stefanía Pantoja-Cabrera ◽  
...  
Keyword(s):  
Relevant Information ◽  
Population Based ◽  
Galapagos Islands ◽  
Maritime Transportation ◽  
Floating Population ◽  
In Situ Observation ◽  
Galápagos Islands ◽  
The Impact ◽  
Official Sources

The Galápagos Islands are one of the biggest marine reserves in the world, home to a complex dynamic between its inhabitants, tourists, and biodiversity. Therefore, control over the logistics surrounding the resulting human mobilization process is fundamental to minimize the impact on the Islands' natural resources. This research gathers relevant information regarding the operation of the maritime transportation system of the islands and the waste management of its floating population based on official sources as well as in-situ observation. This chapter includes three sections with the purpose of maximizing the range of information analyzed. The first section covers the maritime cargo transportation from the continent to the islands. The second one covers the transportation of people between the islands, and the third covers the transportation and management of waste produced by each island. The information covers the institutions and policies that govern each of the systems considered and can serve to optimize the transportation logistics of the Galápagos Islands.

scholarly journals Iodine speciation and size distribution in ambient aerosols at a coastal new particle formation hotspot in China

2019 ◽  
Vol 19 (6) ◽  
pp. 4025-4039 ◽  
Author(s):  
Huan Yu ◽  
Lili Ren ◽  
Xiangpeng Huang ◽  
Mingjie Xie ◽  
Jun He ◽  
...  
Keyword(s):  
Particle Formation ◽  
Coastal Areas ◽  
Aerosol Sample ◽  
Size Distributions ◽  
New Particle Formation ◽  
Nucleation Mode ◽  
Iodine Species ◽  
Organic Iodine ◽  
Iodine Compounds ◽  
Iodine Speciation

Abstract. Intense new particle formation (NPF) events were observed in the coastal atmosphere during algae growth and farming season at Xiangshan gulf of the east China coast. High nucleation-mode iodine concentrations measured by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) confirmed that the NPF events were induced by iodine species. Our study provides important information on iodine speciation, size distributions, and its role in NPF in the context of heavy air pollution in China's coastal areas. For the first time, we identified 5 inorganic iodine species, 45 organic iodine compounds (35 molecular formulas), and a group of iodide–organic adducts in aerosols. The concentrations and size distributions of iodine species down to 10 nm were measured during the iodine-induced NPF, continental NPF, and non-NPF days at the coastal site and compared to those at an inland site. The iodine in the above four aerosol sample types were characterized by iodate, aromatic iodine compounds, iodoacetic acid or iodopropenoic acid, and iodide–organic adducts, respectively. Iodide and organic iodine compounds were found in the nucleation-mode particles; however, it is still not clear whether they contributed to nucleation or just new particle growth. Wild algae, as well as farmed algae, could be an important NPF source in China's coastal areas.

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