Source identification of aerosol chemical composition in the Atlas region of North Africa.

2021 ◽  
Author(s):  
Nabil Deabji ◽  
Khanneh Wadinga Fomba ◽  
Eduardo José dos Santos Souza ◽  
Hartmut Herrmann
Keyword(s):  
High Altitude ◽  
Complex Mixture ◽  
Saharan Dust ◽  
Atmospheric Composition ◽  
Urban Site ◽  
Chemical Components ◽  
Research Station ◽  
African Region ◽  
Aerosol Composition ◽  
The Impact

<p>Aerosol particles are important constituents of the atmosphere due to their role in controlling climate-related processes. In addition, their impacts on air quality and human health make it essential to study. However, the characterization and the identification of natural and anthropogenic atmospheric particles can be challenging due to the complex mixture occurring during atmospheric transport. Background locations such as high-altitude sites provide valuable infrastructure for obtaining representative data for understanding various pathways for aerosol interactions useful in assessing atmospheric composition. However, information about aerosol characteristics at high-altitude in the African regions and their relation to urban aerosol composition is still not well understood. In the present study, PM<sub>10</sub> and PM<sub>2.5</sub> particulate matter was characterized at two different sites in the North African region of Morocco. A background site located at the newly established AM5 research station in the Middle Atlas region at an altitude of 2100 m and an urban site situated in a polluted city, Fez. The goal was to determine chemical components, evaluate Saharan dust’s role on the PM10 concentrations between the sites, and assess the impact of urban pollution on background aerosol composition. The results indicate that the background aerosol composition is influenced by both regional and trans-regional transport. Despite the site's proximity to the Sahara Desert, the deserts influence on the atmospheric composition was observed for only 22% of the time and this was mainly seasonal. Marine air masses were more dominant with a mixture of sea salt and polluted aerosol from the coastal regions especially during wintertime. Furthermore, high concentrations of mineral dust were observed during the daytime due to the resuspension of road dust. At the same time, an increase of PAHs and anthropogenic metals such as Pb, Ni, and Cu were found during the nighttime because of the boundary layer variation. The Fez's urban site is characterized by a high contribution of elemental carbon (6%) and organic biomass tracers (3%) such as Levoglucosane and 4-nitrophenol.</p>

scholarly journals The contribution of Saharan dust to the ice nucleating particle concentrations at the High Altitude Station Jungfraujoch (3580 m a.s.l.), Switzerland

2021 ◽  
Author(s):  
Cyril Brunner ◽  
Benjamin Tobias Brem ◽  
Martine Collaud Coen ◽  
Franz Conen ◽  
Maxime Hervo ◽  
...  
Keyword(s):  
High Altitude ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Dust Particles ◽  
Ice Formation ◽  
Research Station ◽  
Backscatter Signal ◽  
Dust Mass ◽  
The Impact ◽  
Mass Concentrations

Abstract. The ice phase in mixed-phase clouds has a pivotal role in global precipitation formation as well as for Earth's radiative budget. Above 235 K, sparse particles with the special ability to initiate ice formation, ice nucleating particles (INPs), are responsible for primary ice formation within these clouds. However, the abundance and distribution of INPs remain largely unknown. Mineral dust is known to be the most abundant INP in the atmosphere at temperatures colder than 258 K. To better constrain and quantify the impact of mineral dust on ice nucleation, we investigate the frequency of Saharan dust events (SDEs) and their contribution to the INP number concentration at 243 K and at a saturation ratio with respect to liquid water (Sw) of 1.04 at the High Altitude Research Station Jungfraujoch (JFJ; 3580 m a.s.l.) from February to December 2020. Using the single scattering albedo Angström exponent, satellite retrieved dust mass concentrations, simulated tropospheric residence times, and the attenuated backscatter signal from a ceilometer as proxies, we detected 26 SDEs, which in total contributed to 17 % of the time span analyzed. We found every SDE to show an increase in median INP concentrations compared to that of all non-SDE periods, however, not always statistically significant. Median INP concentrations of individual SDEs spread between 1.7 and 161 INP std L−1, thus, two orders of magnitude. In the entire period analyzed, 74.7 ± 0.2 % of all INPs were measured during SDEs. Based on satellite retrieved dust mass concentrations, we argue that mineral dust is also present at the JFJ outside of SDEs, but at much lower concentrations, thus still contributing to the INP population. We estimate 97.0 ± 0.3 % of all INPs active in the immersion mode at 243 K Sw = 1.04 at the JFJ to be mineral dust particles. Overall, we found INP number concentrations to follow a leptokurtic log-normal frequency distribution. We found the INP number concentrations during SDEs to correlate with the ceilometer backscatter signals from a ceilometer located 4.5 km north of the JFJ and 1510 m lower in altitude, thus scanning the air masses at the same altitude as the JFJ. Using the European ceilometer network allows studying the atmospheric pathway of mineral dust plumes over a large domain, which we demonstrate in two case studies. These studies showed that mineral dust plumes form ice crystals at cirrus altitudes, which then sediment to lower altitudes. Upon sublimation in dryer air layers, the residual particles are left potentially pre-activated. Future improvements to the sampling lines of INP counters are required to study if these particles are indeed pre-activated, leading to larger INP number concentrations than reported here.

scholarly journals The contribution of Saharan dust to the ice-nucleating particle concentrations at the High Altitude Station Jungfraujoch (3580 m a.s.l.), Switzerland

2021 ◽  
Vol 21 (23) ◽  
pp. 18029-18053
Author(s):  
Cyril Brunner ◽  
Benjamin T. Brem ◽  
Martine Collaud Coen ◽  
Franz Conen ◽  
Maxime Hervo ◽  
...  
Keyword(s):  
High Altitude ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Dust Particles ◽  
Ice Formation ◽  
Research Station ◽  
Backscatter Signal ◽  
Dust Mass ◽  
The Impact ◽  
Mass Concentrations

Abstract. The ice phase in mixed-phase clouds has a pivotal role in global precipitation formation as well as for Earth's radiative budget. Above 235 K, sparse particles with the special ability to initiate ice formation, ice-nucleating particles (INPs), are responsible for primary ice formation within these clouds. Mineral dust has been found to be one of the most abundant INPs in the atmosphere at temperatures colder than 258 K. However, the extent of the abundance and distribution of INPs remains largely unknown. To better constrain and quantify the impact of mineral dust on ice nucleation, we investigate the frequency of Saharan dust events (SDEs) and their contribution to the INP number concentration at 243 K and at a saturation ratio with respect to liquid water (Sw) of 1.04 at the High Altitude Research Station Jungfraujoch (JFJ; 3580 m a.s.l.) from February to December 2020. Using the single-scattering albedo Ångström exponent retrieved from a nephelometer and an Aethalometer, satellite-retrieved dust mass concentrations, simulated tropospheric residence times, and the attenuated backscatter signal from a ceilometer as proxies, we detected 26 SDEs, which in total contributed to 17 % of the time span analyzed. We found every SDE to show an increase in median INP concentrations compared to those of all non-SDE periods; however, they were not always statistically significant. Median INP concentrations of individual SDEs spread between 1.7 and 161 INP std L−1 and thus 2 orders of magnitude. In the entire period analyzed, 74.7 ± 0.2 % of all INPs were measured during SDEs. Based on satellite-retrieved dust mass concentrations, we argue that mineral dust is also present at JFJ outside of SDEs but at much lower concentrations, thus still contributing to the INP population. We estimate that 97 % of all INPs active in the immersion mode at 243 K and Sw=1.04 at JFJ are dust particles. Overall, we found INP number concentrations to follow a leptokurtic lognormal frequency distribution. We found the INP number concentrations during SDEs to correlate with the ceilometer backscatter signals from a ceilometer located 4.5 km north of JFJ and 1510 m lower in altitude, thus scanning the air masses at the same altitude as JFJ. Using the European ceilometer network allows us to study the atmospheric pathway of mineral dust plumes over a large domain, which we demonstrate in two case studies. These studies showed that mineral dust plumes form ice crystals at cirrus altitudes, which then sediment to lower altitudes. Upon sublimation in dryer air layers, the residual particles are left potentially pre-activated. Future improvements to the sampling lines of INP counters are required to study whether these particles are indeed pre-activated, leading to larger INP number concentrations than reported here.

scholarly journals Vertically-resolved Characteristics of Air Pollution during Two Severe Winter Haze Episodes in Urban Beijing, China

2017 ◽  
Author(s):  
Qingqing Wang ◽  
Yele Sun ◽  
Weiqi Xu ◽  
Wei Du ◽  
Libo Zhou ◽  
...  
Keyword(s):  
Mixing Layer ◽  
Urban Site ◽  
Formation Mechanisms ◽  
Vertical Profiles ◽  
Severe Winter ◽  
Aerosol Composition ◽  
Layer Height ◽  
Mixing Layer Height ◽  
The Impact ◽  
Beijing China

Abstract. We conducted the first real-time continuous vertical measurements of particle extinction (bext), gaseous NO2, and black carbon (BC) from ground level to 260 m during two severe winter haze episodes at an urban site in Beijing, China. Our results illustrated four distinct types of vertical profiles: 1) uniform vertical distributions (37 % of the time) with vertical differences less than 5 %; 2) higher values at lower altitudes (29 %); 3) higher values at higher altitudes (16 %), and 4) significant decreases at the heights of ~ 100–150 m (14 %). Further analysis demonstrated that vertical convection as indicated by mixing layer height, temperature inversion, and local emissions are three major factors affecting the changes in vertical profiles. Particularly, the formation of Type 4 was strongly associated with the stratified layer that was formed due to the interactions of different air masses and temperature inversions. Aerosol composition was substantially different below and above the transition heights with ~ 20–30 % higher contributions of local sources (e.g., biomass burning and cooking) at lower altitudes. A more detailed evolution of vertical profiles and their relationship with the changes in source emissions, mixing layer height, and aerosol chemistry was illustrated by a case study. BC showed overall similar vertical profiles as those of bext (R2 = 0.92 and 0.69 in November and January, respectively). While NO2 was correlated with bext for most of the time, the vertical profiles of bext/NO2 varied differently for different profiles, indicating the impact of chemical transformation on vertical profiles. Our results also showed that more comprehensive vertical measurements (e.g., more aerosol and gaseous species) at higher altitudes in the megacities are needed for a better understanding of the formation mechanisms and evolution of severe haze episodes in China.

scholarly journals The Horizontal Ice Nucleation Chamber (HINC): INP measurements at conditions relevant for mixed-phase clouds at the High Altitude Research Station Jungfraujoch

2017 ◽  
Vol 17 (24) ◽  
pp. 15199-15224 ◽  
Author(s):  
Larissa Lacher ◽  
Ulrike Lohmann ◽  
Yvonne Boose ◽  
Assaf Zipori ◽  
Erik Herrmann ◽  
...  
Keyword(s):  
High Altitude ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Saharan Dust ◽  
Research Station ◽  
Minimum Detectable Concentration ◽  
The North ◽  
New Instrument ◽  
Marine Air ◽  
Mixed Phase Clouds

Abstract. In this work we describe the Horizontal Ice Nucleation Chamber (HINC) as a new instrument to measure ambient ice-nucleating particle (INP) concentrations for conditions relevant to mixed-phase clouds. Laboratory verification and validation experiments confirm the accuracy of the thermodynamic conditions of temperature (T) and relative humidity (RH) in HINC with uncertainties in T of ±0.4 K and in RH with respect to water (RHw) of ±1.5 %, which translates into an uncertainty in RH with respect to ice (RHi) of ±3.0 % at T > 235 K. For further validation of HINC as a field instrument, two measurement campaigns were conducted in winters 2015 and 2016 at the High Altitude Research Station Jungfraujoch (JFJ; Switzerland, 3580 m a. s. l. ) to sample ambient INPs. During winters 2015 and 2016 the site encountered free-tropospheric conditions 92 and 79 % of the time, respectively. We measured INP concentrations at 242 K at water-subsaturated conditions (RHw = 94 %), relevant for the formation of ice clouds, and in the water-supersaturated regime (RHw = 104 %) to represent ice formation occurring under mixed-phase cloud conditions. In winters 2015 and 2016 the median INP concentrations at RHw = 94 % was below the minimum detectable concentration. At RHw = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (std L−1; normalized to standard T of 273 K and pressure, p, of 1013 hPa) and 4.7 std L−1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber (PINC) of 2.2 std L−1 at the same location. During winter 2015, two events caused the INP concentrations at RHw = 104 % to significantly increase above the campaign average. First, an increase to 72.1 std L−1 was measured during an event influenced by marine air, arriving at the JFJ from the North Sea and the Norwegian Sea. The contribution from anthropogenic or other sources can thereby not be ruled out. Second, INP concentrations up to 146.2 std L−1 were observed during a Saharan dust event. To our knowledge this is the first time that a clear enrichment in ambient INP concentration in remote regions of the atmosphere is observed during a time of marine air mass influence, suggesting the importance of marine particles on ice nucleation in the free troposphere.

scholarly journals First insights into northern Africa high-altitude background aerosol chemical composition and source influences

2021 ◽  
Vol 21 (24) ◽  
pp. 18147-18174
Author(s):  
Nabil Deabji ◽  
Khanneh Wadinga Fomba ◽  
Souad El Hajjaji ◽  
Abdelwahid Mellouki ◽  
Laurent Poulain ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
High Altitude ◽  
North Africa ◽  
Mineral Dust ◽  
Water Soluble ◽  
Atmospheric Composition ◽  
Chemical Compositions ◽  
Aerosol Composition ◽  
Aerosol Chemical Composition

Abstract. Field measurements were conducted to determine aerosol chemical composition at a newly established remote high-altitude site in North Africa at the Atlas Mohammed V (AMV) atmospheric observatory located in the Middle Atlas Mountains. The main objectives of the present work are to investigate the variations in the aerosol composition and better assess global and regional changes in atmospheric composition in North Africa. A total of 200 particulate matter (PM10) filter samples were collected at the site using a high-volume (HV) collector in a 12 h sampling interval from August to December 2017. The chemical composition of the samples was analyzed for trace metals, water-soluble ions, organic carbon (OC/EC), aliphatic hydrocarbons, and polycyclic aromatic hydrocarbon (PAH) contents. The results indicate that high-altitude aerosol composition is influenced by both regional and transregional transport of emissions. However, local sources play an important role, especially during low wind speed periods, as observed for November and December. During background conditions characterized by low wind speeds (avg. 3 m s-1) and mass concentrations in the range from 9.8 to 12 μg m-3, the chemical composition is found to be dominated by inorganic elements, mainly suspended dust (61 %) and ionic species (7 %), followed by organic matter (7 %), water content (12 %), and unidentified mass (11 %). Despite the proximity of the site to the Sahara, its influence on the atmospheric composition at this high-altitude site was mainly seasonal and accounted for only 22 % of the sampling duration. Biogenic organics contributed up to 7 % of the organic matter with high contributions from compounds such as heneicosane, hentriacontane, and nonacosane. The AMV site is dominated by four main air mass inflows, which often leads to different aerosol chemical compositions. Mineral dust influence was seasonal and ranged between 21 % and 74 % of the PM mass, with peaks observed during the summer, and was accompanied by high concentrations of SO42- of up to 3.0 μg m-3. During winter, PM10 concentrations are low (<30 μg m-3), the influence of the desert is weaker, and the marine air masses (64 %) are more dominant with a mixture of sea salt and polluted aerosol from the coastal regions (Rabat and Casablanca). During the daytime, mineral dust contribution to PM increased by about 42 % because of road dust resuspension. In contrast, during nighttime, an increase in the concentrations of alkanes, PAHs, alkane-2-ones, and anthropogenic metals such as Pb, Ni, and Cu was found due to variations in the boundary layer height. The results provide the first detailed seasonal and diurnal variation of the aerosol chemical composition, which is valuable for long-term assessment of climate and regional influence of air pollution in North Africa.

scholarly journals First insights into Northern Africa high-altitude background aerosol chemical composition and source influences

2021 ◽  
Author(s):  
Nabil Deabji ◽  
Khanneh Wadinga Fomba ◽  
Souad El Hajjaji ◽  
Abdelwahid Mellouki ◽  
Hartmut Herrmann
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
High Altitude ◽  
Field Measurements ◽  
High Volume ◽  
Ionic Species ◽  
Atmospheric Composition ◽  
Chemical Compositions ◽  
Aerosol Composition ◽  
Aerosol Chemical Composition

Abstract. Field measurements were conducted to determine aerosol chemical composition in a newly established remote high-altitude site in North Africa to investigate the variations in aerosol composition useful in assessing global and regional changes in atmospheric composition. Particulate matter (PM10) filter samples (200) were collected at the Atlas Mohammed V atmospheric observatory (AM5) located in the Middle-Atlas Mountains in Morocco using a high-volume (HV) collector in a 12 h sampling interval from August to December 2017. The chemical composition of the samples was analyzed for trace metals, ions, elemental carbon, organic carbon, aliphatic hydrocarbons, and polycyclic aromatic hydrocarbon (PAHs) content. The results indicate that high-altitudes aerosol composition is influenced by both regional as well as trans-regional transport of emissions. However, local sources play an important role, especially during low wind speed periods, as observed for November and December. Despite the proximity of the site to the Sahara Desert, its influence on the atmospheric composition at this high-altitude site was mainly seasonal and accounted for only 14 % of the sampling duration. Background conditions at this remote site are characterized by low wind speeds (Av. 2.5 m/s) and mass concentrations in the range of 9.8 and 20 µg/m3. The chemical composition is found to be dominated by inorganic elements, mainly suspended dust (47 %) and ionic species (16 %), followed by organic matter (15 %), water content (12 %), and indeterminate mass (9 %). Biogenic organics contributed up to 7 % of the organic matter with high contributions from compounds such as Nonacosane, Heptacosane, and 2-Pentadecanone. The AM5 site is dominated by four main air mass inflow, which often leads to different aerosol chemical compositions. Mineral dust influenced was seasonal and ranged between 20 and 70 % of the PM mass with peaks observed during the summer and was accompanied by high concentrations of SO42− of up to 1.3 µg/m3. During winter, PM10 concentrations are low (

Investigating chemical composition of the troposphere over the Russian Arctic using the "Optik" Tu-134 aircraft laboratory

2020 ◽  
Author(s):  
Boris D. Belan ◽  
Pavel N. Antokhin ◽  
Mikhail Yu. Arshinov ◽  
Sergey B. Belan ◽  
Denis K. Davydov ◽  
...  
Keyword(s):  
Satellite Data ◽  
Land Surface ◽  
General Scheme ◽  
Water Area ◽  
Kara Sea ◽  
Atmospheric Composition ◽  
The Arctic ◽  
Aerosol Composition ◽  
The Impact

&lt;p&gt;The need to undertake a comprehensive investigation of the atmospheric composition over the Russian segment of the Arctic is caused by a serious lack and irregularity in obtaining observational data from this regio of the Earth. In addition, a comparison of the aircraft in-situ measurements with satellite data retrieved for the Kara Sea region in 2017 revealed large uncertainties in determining the vertical distribution of greenhouse gas concentrations using remote sensing methods. The development and improvement of the last ones needs at least their periodic verification by means of undertaking precise in-situ aircraft measurements.&lt;/p&gt;&lt;p&gt;The general scheme of the proposed experiment is as follows (map is attached): flight from Novosibirsk to Naryan-Mar via Sabetta. From Naryan-Mar, flight to a water area of the Bering Sea (up to 1000 km). Flight from Naryan-Mar to Sabetta. From here, flight to a water area of the Kara Sea (up to 1000 km). Then, flight to Tiksi. Flight from Tiksi to a water area of the Laptev Sea (up to 1000 km). Flight to Chokurdakh or Chersky. From there, flight to a water area of the East Siberian Sea (up to 1000 km). Flight to Cape Schmidt. Flight to a water area of the Chukchi Sea (up to 1000 km). Return route: Cape Shmidt&amp;#8211;Chersky (or Chokurdah)&amp;#8211;Yakutsk&amp;#8211;Bratsk&amp;#8211;Novosibirsk. It will take about 100 hours of flying time to implement the entire aircraft campaign. Campaign period is about 2-3 weeks. It is better to undertake the campaign during summer when the ocean is open. Flights over the land surface are assumed to be undertaken from 0.5 km to 11 km above ground level while above the sea from 0.2 km to 11 km. The flight profile is variable from the maximum possible height to the minimum allowed one. Vertical profiles of gas and aerosol composition will be obtained, including black carbon and organic components, as well as basic meteorological quantities.&lt;/p&gt;&lt;p&gt;Satellite data will be verified that do not yet provide acceptable accuracy. For the first time, unique information will be obtained over the least explored region of the Arctic, which is crucial for the whole planet in terms of climate formation and the impact of global warming.&lt;/p&gt;

scholarly journals The diurnal and seasonal variability of ice nucleating particles at the High Altitude Station Jungfraujoch (3580 m a.s.l.), Switzerland

2021 ◽  
Author(s):  
Cyril Brunner ◽  
Benjamin Tobias Brem ◽  
Martine Collaud Coen ◽  
Franz Conen ◽  
Martin Steinbacher ◽  
...  
Keyword(s):  
High Altitude ◽  
Diurnal Cycle ◽  
Radiative Properties ◽  
Saharan Dust ◽  
High Time Resolution ◽  
Research Station ◽  
Data Set ◽  
Diurnal Variability ◽  
Special Events ◽  
A Minor

Abstract. Cloud radiative properties, cloud lifetime, and precipitation initiation are strongly influenced by the cloud phase. Between ~ 235 and 273 K, ice nucleating particles (INPs) are responsible for the initial phase transition from the liquid to the ice phase in cloud hydrometeors. This study analyzes immersion-mode INP concentrations measured at 243 K at the High Altitude Research Station Jungfraujoch (3580 m a.s.l.) between February 2020 and January 2021, thereby presenting the longest continuous, high-resolution (20 min) data set of online INP measurements to date. The high time resolution and continuity allow to study the seasonal and the diurnal variability of INPs. After exclusion of special events, like Saharan dust events (SDEs), we found a seasonal cycle of INPs, highest in April (median in spring 3.1 INP std L−1), followed by summer (median: 1.6 INP std L−1) and lowest in fall and winter (median: 0.5 INP std L−1 and 0.7 INP std L−1, respectively). Pollen or subpollen particles were deemed unlikely to be responsible for elevated INP concentrations in spring and summer, as periods with high pollen loads from nearby measurement stations do not coincide with the periods of high INP concentrations. Furthermore, for days when the site was purely in the free troposphere (FT), no diurnal cycle in INP concentrations was observed, while days with boundary layer intrusions (BLI) showed a diurnal cycle. The seasonal and diurnal variability of INPs during periods excluding SDEs is with a factor of 7 and 3.3, respectively, significantly lower than the overall variability observed in INP concentration including SDEs of more than three orders of magnitude, when peak values result from SDEs. The median INP concentration over the analyzed 12 months was 1.2 INP std L−1 for FT periods excluding SDEs, and 1.4 INP std L−1 for both FT and BLI, and incl. SDEs, reflecting that despite SDEs showing strong but comparatively brief INP signals, they have a minor impact on the observed annual median INP concentration.

The impact of atmospheric wet deposition on roof runoff quality in an urbanized area

2015 ◽  
Vol 46 (6) ◽  
pp. 880-892 ◽  
Author(s):  
Hua-Peng Qin ◽  
Qiao-Ling Tang ◽  
Li-Yu Wang ◽  
Guangtao Fu
Keyword(s):  
Organic Acids ◽  
Wet Deposition ◽  
Rainwater Harvesting ◽  
Urban Site ◽  
Chemical Components ◽  
Roof Runoff ◽  
Alkaline Dust ◽  
Rooftop Rainwater Harvesting ◽  
The Impact ◽  
Fast Increase

Understanding the sources of chemical components in roof runoff can help to prevent water quality problems in rooftop rainwater harvesting. To identify the contribution of wet deposition to the mass of components in roof runoff, the samples from air, rainwater, dust buildup and roof runoff were collected from an urban site in Shenzhen of China in 2011–2012. The results indicate that: (1) wet deposition has a dominant contribution to the mass of total organic carbon (TOC), NH4+, NO3–, Cl– and organic acids in the roof runoff, while the mass of NH4+, acetic acid and formic acid in the roof runoff may be greatly reduced by the neutralization between the components with alkaline dust buildup on the rooftop; and (2) wet deposition partially contributes to the mass of Na+, K+, Mg2+, Ca2+, F– and SO42– in the roof runoff, while other factors like dust buildup on the rooftop and chemical reactions also have a non-negligible impact. Furthermore, TOC, NH4+, NO3– and organic acids in the wet deposition are mainly influenced by the atmospheric pollution due to fast increase in fossil fuel consumption (e.g. vehicle emissions). Therefore, the effects of wet deposition should be carefully considered for rooftop rainwater harvesting in urbanized areas.

scholarly journals The Horizontal Ice Nucleation Chamber HINC: INP measurements at Conditions Relevant for Mixed-Phase Clouds at the High Altitude Research Station Jungfraujoch

2017 ◽  
Author(s):  
Larissa Lacher ◽  
Ulrike Lohmann ◽  
Yvonne Boose ◽  
Assaf Zipori ◽  
Erik Herrmann ◽  
...  
Keyword(s):  
High Altitude ◽  
Ice Nucleation ◽  
Mixed Phase ◽  
Saharan Dust ◽  
Research Station ◽  
Minimum Detectable Concentration ◽  
New Instrument ◽  
Order Of Magnitude ◽  
Marine Air ◽  
Mixed Phase Clouds

Abstract. In this work we describe the Horizontal Ice Nucleation Chamber, HINC as a new instrument to measure ambient ice nucleating particle (INP) concentrations for conditions relevant to mixed-phase clouds. Laboratory verification and validation experiments confirm accuracy of the thermodynamic conditions of temperature (T) and relative humidity (RH) in HINC with uncertainties in temperature of ±0.4 K and in RH with respect to water (RHw) of ±1.5 %, which translates to an uncertainty in RH with respect to ice (RHi) of ±3.0 % at T > 235 K. For further validation of HINC as a field instrument, two measurement campaigns were conducted in winters 2015 and 2016 at the High Altitude Research Station Jungfraujoch (JFJ; Switzerland, 3580 m a.s.l.) to sample ambient INPs. During winters 2015 and 2016 the site encountered free tropospheric conditions 92 % and 79 % of the time respectively. We measured INP concentrations at 242 K at water sub-saturated conditions (RHw = 94 %), relevant for the formation of ice clouds, and in the water supersaturated regime (RHw = 103–104 %) to represent ice formation occurring under mixed-phase cloud conditions. In winter 2015 and 2016 the median INP concentrations at RHw = 94 % was below the minimum detectable concentration. At RHw = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (stdL−1; normalized to standard temperature T = 273 K and pressure p = 1013 hPa) and 4.7 stdL−1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber, PINC, of 2.2 stdL−1 at the same location. During winter 2015, two events caused the INP concentrations at RHw = 103–104 % to significantly increase above the campaign average. First, an increase to 72.1 stdL−1 was measured during an event influenced by marine air, coming from the Northern Sea and the Norwegian Sea. Second, INP concentrations up to 146.2 stdL−1 were observed during a Saharan dust event. To our knowledge this is the first time that a clear enrichment in ambient INP concentration is observed during a time of marine air mass influence, indicating the importance of marine particles on ice nucleation in the free troposphere.

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