scholarly journals The seasonal cycle of ice-nucleating particles linked to the abundance of biogenic aerosol in boreal forests

2021 ◽  
Vol 21 (5) ◽  
pp. 3899-3918
Author(s):  
Julia Schneider ◽  
Kristina Höhler ◽  
Paavo Heikkilä ◽  
Jorma Keskinen ◽  
Barbara Bertozzi ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Boreal Forest ◽  
Seasonal Cycle ◽  
Weather Forecasting ◽  
Late Summer ◽  
Active Surface ◽  
Ambient Air ◽  
Ice Nucleation ◽  
Forest Environment ◽  
New Findings

Abstract. Ice-nucleating particles (INPs) trigger the formation of cloud ice crystals in the atmosphere. Therefore, they strongly influence cloud microphysical and optical properties and precipitation and the life cycle of clouds. Improving weather forecasting and climate projection requires an appropriate formulation of atmospheric INP concentrations. This remains challenging as the global INP distribution and variability depend on a variety of aerosol types and sources, and neither their short-term variability nor their long-term seasonal cycles are well covered by continuous measurements. Here, we provide the first year-long set of observations with a pronounced INP seasonal cycle in a boreal forest environment. Besides the observed seasonal cycle in INP concentrations with a minimum in wintertime and maxima in early and late summer, we also provide indications for a seasonal variation in the prevalent INP type. We show that the seasonal dependency of INP concentrations and prevalent INP types is most likely driven by the abundance of biogenic aerosol. As current parameterizations do not reproduce this variability, we suggest a new mechanistic description for boreal forest environments which considers the seasonal variation in INP concentrations. For this, we use the ambient air temperature measured close to the ground at 4.2 m height as a proxy for the season, which appears to affect the source strength of biogenic emissions and, thus, the INP abundance over the boreal forest. Furthermore, we provide new INP parameterizations based on the Ice Nucleation Active Surface Site (INAS) approach, which specifically describes the ice nucleation activity of boreal aerosols particles prevalent in different seasons. Our results characterize the boreal forest as an important but variable INP source and provide new perspectives to describe these new findings in atmospheric models.

scholarly journals The seasonal cycle of ice-nucleating particles linked to the abundance of biogenic aerosol in boreal forests

2020 ◽  
Author(s):  
Julia Schneider ◽  
Kristina Höhler ◽  
Paavo Heikkilä ◽  
Jorma Keskinen ◽  
Barbara Bertozzi ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Boreal Forest ◽  
Seasonal Cycle ◽  
Weather Forecasting ◽  
Late Summer ◽  
Active Surface ◽  
Ambient Air ◽  
Ice Nucleation ◽  
Forest Environment ◽  
New Findings

Abstract. Ice-nucleating particles (INPs) trigger the formation of cloud ice crystals in the atmosphere. Therefore, they strongly influence cloud microphysical and optical properties, as well as precipitation and the life cycle of clouds. Improving weather forecasting and climate projection requires an appropriate formulation of atmospheric INP concentrations. This remains challenging, as the global INP distribution and variability depend on a variety of aerosol types and sources, and neither their short-term variability nor their long-term seasonal cycles are well covered by continuous measurements. Here, we provide the first year-long set of observations with a pronounced INP seasonal cycle in a boreal forest environment. Besides the observed seasonal cycle in INP concentrations with a minimum in wintertime and maxima in early and late summer, we also provide indications for a seasonal variation in the prevalent INP type. We show that the seasonal dependency of INP concentrations and prevalent INP types is most likely driven by the abundance of biogenic aerosol. As current parameterizations do not reproduce this variability, we suggest a new parameterization approach, which considers the seasonal variation of INP concentrations. For this, we use the ambient air temperature as a proxy for the season which affects the source strength of biogenic emissions and by that the INP abundance over the boreal forest areas. Furthermore, we provide new INP parameterizations based on the Ice Nucleation Active Surface Site (INAS) approach, which specifically describes the ice nucleation activity of boreal aerosols particles prevalent in different seasons. Our results characterize the boreal forest as an important but variable INP source and provide new perspectives to describe these new findings in atmospheric models.

The seasonal cycle of biogenic ice-nucleating particles in a boreal forest environment

2020 ◽  
Author(s):  
Julia Schneider ◽  
Kristina Höhler ◽  
Paavo Heikkilä ◽  
Jorma Keskinen ◽  
Barbara Bertozzi ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Seasonal Cycle ◽  
Field Measurements ◽  
Climate Projections ◽  
Research Station ◽  
Forest Environment ◽  
Institute Of Technology ◽  
The University ◽  
Karlsruhe Institute

<p>By triggering the formation of cloud ice crystals in the atmosphere, ice-nucleating particles (INP) strongly influence cloud properties, cloud life cycle and precipitation. Describing the abundance of atmospheric INPs in weather forecasts and climate projections remains challenging, as the global distribution and variability of INPs depend on a variety of different aerosol types and sources. Although widespread field measurements have been conducted, neither short-term variability nor long-term seasonal cycles have yet been well characterized by continuous measurements. In 2018, the University of Helsinki and the Karlsruhe Institute of Technology (KIT) initiated a field campaign HyICE to perform comprehensive long-term INP measurements in the Finnish boreal forest. The campaign took place in Hyytiälä, Southern Finland at the University of Helsinki SMEARII research station (Hari and Kulmala, 2005). KIT provided the INSEKT (Ice Nucleation Spectrometer of the Karlsruhe Institute of Technology) to analyse the INP content of ambient aerosols sampled on filters. INSEKT is able to measure INP concentrations in the immersion-freezing mode at temperatures between 273 K and 248 K. The measurements started in March 2018 and ended in May 2019, which provides a unique continuous long-term time series of INP concentrations for over more than one year with a time resolution of about one to three days. This long-term observation record is used to examine systematic seasonal trends in the INP concentrations and to find meteorological and aerosol related parameters to describe the observed trends and variabilities. These findings will enable to find new parameterizations of atmospheric INP concentrations, as current parameterizations do not reproduce the observed seasonal cycle yet. In addition to INP concentration measurements, heat treatment tests of the aerosol samples have been conducted providing additional indications about the INP types dominating the INP population in the boreal forest, also in dependence on the season. Finally, this contribution will summarize and discuss major findings and implications from the HyICE long-term INP observation.</p><p> </p><p>Hari and Kulmala (2005), Boreal Environ Res. 14, 315-322.</p>

scholarly journals Spatio-temporal variation in number and production of neustonic and planktonic bacteria inhabiting polluted estuarine harbour channel

2021 ◽  
Vol 203 (9) ◽  
pp. 5547-5559
Author(s):  
Piotr Perliński ◽  
Zbigniew J. Mudryk ◽  
Marta Zdanowicz ◽  
Łukasz Kubera
Keyword(s):  
Seasonal Variation ◽  
Secondary Production ◽  
Seasonal Cycle ◽  
Subsurface Water ◽  
Surface Microlayer ◽  
Water Basin ◽  
Planktonic Bacteria ◽  
Microbiological Parameters ◽  
Spatio Temporal ◽  
Number Of Bacteria

AbstractThe aim of this paper was to determine the abundance and secondary production by bacteria inhabiting the surface microlayer and subsurface water in a specific water basin, i.e., polluted estuarine harbour channel. In a 3-year seasonal cycle, the total number of bacteria and their biomass were higher in the surface microlayer (SML) 7.57 × 108cells dm−3 and 15.86 µg C dm−3 than in the subsurface water (SSW) 4.25 × 108cells dm−3 and 9.11 µg C dm−3 of the studied channel. The opposite relationship was noted in the level of the secondary production (SML—37.16 μg C dm−3 h−1, SSW—60.26 μg C dm−3 h−1) in this water basin. According to the analysed microbiological parameters, the total number of bacteria and secondary production varied along the horizontal profile in the water of the studied channel. The total number of bacteria and their secondary production showed the seasonal variation as well.

Seasonal variation, risk assessment and source estimation of PM 10 and PM10-bound PAHs in the ambient air of Chiang Mai and Lamphun, Thailand

2008 ◽  
Vol 154 (1-4) ◽  
pp. 197-218 ◽  
Author(s):  
Petch Pengchai ◽  
Somporn Chantara ◽  
Khajornsak Sopajaree ◽  
Sunanta Wangkarn ◽  
Urai Tengcharoenkul ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Seasonal Variation ◽  
Ambient Air ◽  
Chiang Mai ◽  
Source Estimation ◽  
Pm 10

scholarly journals Amines in boreal forest air at SMEAR II station in Finland

2018 ◽  
Vol 18 (9) ◽  
pp. 6367-6380 ◽  
Author(s):  
Marja Hemmilä ◽  
Heidi Hellén ◽  
Aki Virkkula ◽  
Ulla Makkonen ◽  
Arnaud P. Praplan ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Gas Phase ◽  
Particle Number ◽  
Detection Limits ◽  
Ambient Air ◽  
Monthly Means ◽  
Ammonium Ions ◽  
Quadrupole Mass ◽  
Concentration Data ◽  
Diurnal Variability

Abstract. We measured amines in boreal forest air in Finland both in gas and particle phases with 1 h time resolution using an online ion chromatograph (instrument for Measuring AeRosols and Gases in Ambient Air – MARGA) connected to an electrospray ionization quadrupole mass spectrometer (MS). The developed MARGA-MS method was able to separate and detect seven different amines: monomethylamine (MMA), dimethylamine (DMA), trimethylamine (TMA), ethylamine (EA), diethylamine (DEA), propylamine (PA), and butylamine (BA). The detection limits of the method for amines were low (0.2–3.1 ng m−3), the accuracy of IC-MS analysis was 11–37 %, and the precision 10–15 %. The proper measurements in the boreal forest covered about 8 weeks between March and December 2015. The amines were found to be an inhomogeneous group of compounds, showing different seasonal and diurnal variability. Total MMA (MMA(tot)) peaked together with the sum of ammonia and ammonium ions already in March. In March, monthly means for MMA were < 2.4 and 6.8 ± 9.1 ng m−3 in gas and aerosol phases, respectively, and for NH3 and NH4+ these were 52 ± 16 and 425 ± 371 ng m−3, respectively. Monthly medians in March for MMA(tot), NH3, and NH4+ were < 2.4, 19 and 90 ng m−3, respectively. DMA(tot) and TMA(tot) had summer maxima indicating biogenic sources. We observed diurnal variation for DMA(tot) but not for TMA(tot). The highest concentrations of these compounds were measured in July. Then, monthly means for DMA were < 3.1 and 8.4 ± 3.1 ng m−3 in gas and aerosol phases, respectively, and for TMA these were 0.4 ± 0.1 and 1.8 ± 0.5 ng m−3. Monthly medians in July for DMA were below the detection limit (DL) and 4.9 ng m−3 in gas and aerosol phases, respectively, and for TMA these were 0.4 and 1.4 ng m−3. When relative humidity of air was > 90 %, gas-phase DMA correlated well with 1.1–2 nm particle number concentration (R2=0.63) suggesting that it participates in atmospheric clustering. EA concentrations were low all the time. Its July means were < 0.36 and 0.4 ± 0.4 ng m−3 in gas and aerosol phases, respectively, but individual concentration data correlated well with monoterpene concentrations in July. Monthly means of PA and BA were below detection limits at all times.

scholarly journals Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic)

2014 ◽  
Vol 15 (3) ◽  
pp. 475 ◽  
Author(s):  
S. GARCIA-SANZ ◽  
P. G. NAVARRO ◽  
F. TUYA
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Late Summer ◽  
Paracentrotus Lividus ◽  
Abundant Species ◽  
Late Winter ◽  
Gran Canaria ◽  
Arbacia Lixula

Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula) at Gran Canaria Island (eastern Atlantic) via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds) within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula) with the most conspicuous species (D. africanum) in the study area.

scholarly journals Hygroscopicity, CCN and volatility properties of submicron atmospheric aerosol in a boreal forest environment during the summer of 2010

2013 ◽  
Vol 13 (11) ◽  
pp. 29097-29136 ◽  
Author(s):  
J. Hong ◽  
S. A. K. Häkkinen ◽  
M. Paramonov ◽  
M. Äijälä ◽  
J. Hakala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Atmospheric Aerosol ◽  
Cloud Condensation Nuclei ◽  
Relative Mass ◽  
Particle Sizes ◽  
Volatile Material ◽  
Differential Mobility ◽  
Forest Environment ◽  
Large Particles ◽  
Aerosol Volume

Abstract. The Volatility-Hygroscopicity Tandem Differential Mobility Analyzer (VH-TDMA) was applied to study the hygroscopicity and volatility properties of submicron atmospheric aerosol in a boreal forest environment in Hyytiälä, Finland during the summer of 2010. Aitken and accumulation mode particles (50 nm, 75 nm and 110 nm) were investigated. The results suggest that the particles were internally mixed at all sizes. Hygroscopicity was found to increase with size. The relative mass fraction of organics and SO42− is probably the major contributor to the fluctuation of the hygroscopicity for all particle sizes. The Cloud Condensation Nuclei counter (CCNc)-derived hygroscopicity parameter κ was slightly higher than κ calculated from VH-TDMA data under sub-saturated conditions, which can be explained by the fact that particulate organics have a different degree of dissolution in sub- and supersaturated conditions. Also, the size-resolved volatility properties of particles were investigated. Upon heating, small particles evaporated more compared to large particles. There was a significant amount of aerosol volume (non-volatile material) left even at heating temperatures above 280 °C. Using size resolved volatility-hygroscopicity analysis, we concluded that there was always hygroscopic material remaining in the particles of different sizes at all different heating temperatures, even above 280 °C. This indicates that the observed non-volatile aerosol material was not consisting solely of black carbon.

scholarly journals A new temperature- and humidity-dependent surface site density approach for deposition ice nucleation

2015 ◽  
Vol 15 (7) ◽  
pp. 3703-3717 ◽  
Author(s):  
I. Steinke ◽  
C. Hoose ◽  
O. Möhler ◽  
P. Connolly ◽  
T. Leisner
Keyword(s):  
Contact Angle ◽  
Relative Humidity ◽  
Active Surface ◽  
Ice Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Aerosol Size Distribution ◽  
Surface Site ◽  
Linear Behavior ◽  
Temperature And Humidity

Abstract. Deposition nucleation experiments with Arizona Test Dust (ATD) as a surrogate for mineral dusts were conducted at the AIDA cloud chamber at temperatures between 220 and 250 K. The influence of the aerosol size distribution and the cooling rate on the ice nucleation efficiencies was investigated. Ice nucleation active surface site (INAS) densities were calculated to quantify the ice nucleation efficiency as a function of temperature, humidity and the aerosol surface area concentration. Additionally, a contact angle parameterization according to classical nucleation theory was fitted to the experimental data in order to relate the ice nucleation efficiencies to contact angle distributions. From this study it can be concluded that the INAS density formulation is a very useful tool to describe the temperature- and humidity-dependent ice nucleation efficiency of ATD particles. Deposition nucleation on ATD particles can be described by a temperature- and relative-humidity-dependent INAS density function ns(T, Sice) with ns(xtherm) = 1.88 ×105 · exp(0.2659 · xtherm) [m−2] , (1) where the temperature- and saturation-dependent function xtherm is defined as xtherm = −(T−273.2)+(Sice−1) ×100, (2) with the saturation ratio with respect to ice Sice >1 and within a temperature range between 226 and 250 K. For lower temperatures, xtherm deviates from a linear behavior with temperature and relative humidity over ice. Also, two different approaches for describing the time dependence of deposition nucleation initiated by ATD particles are proposed. Box model estimates suggest that the time-dependent contribution is only relevant for small cooling rates and low number fractions of ice-active particles.

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