Surface-to-mountaintop transport characterised by radon observations at the Jungfraujoch
TL;DR: In this article, the authors quantify the land-surface influence at Jungfraujoch hour by hour and detect the presence of anabatic winds on a daily basis during 2010-2011, but only from April to September.
Abstract: . Atmospheric composition measurements at Jungfraujoch are affected intermittently by boundary-layer air which is brought to the station by processes including thermally driven (anabatic) mountain winds. Using observations of radon-222, and a new objective analysis method, we quantify the land-surface influence at Jungfraujoch hour by hour and detect the presence of anabatic winds on a daily basis. During 2010–2011, anabatic winds occurred on 40% of days, but only from April to September. Anabatic wind days were associated with warmer air temperatures over a large fraction of Europe and with a shift in air-mass properties, even when comparing days with a similar mean radon concentration. Excluding days with anabatic winds, however, did not lead to a better definition of the unperturbed aerosol background than a definition based on radon alone. This implies that a radon threshold reliably excludes local influences from both anabatic and non-anabatic vertical-transport processes.
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Karlsruhe Institute of Technology1, ETH Zurich2, Colorado State University3, Pacific Northwest National Laboratory4, German Aerospace Center5, Hebrew University of Jerusalem6, Weizmann Institute of Science7, Paul Scherrer Institute8, Swiss Federal Laboratories for Materials Science and Technology9, University of Toronto10
TL;DR: In this paper, the authors quantify the number of ice nucleating particles (INPs) in the free troposphere (FT) as measured at the High Altitude Research Station Jungfraujoch (JFJ), during the winter, spring, and summer of the years 2014-2017.
Abstract: Clouds containing ice are vital for precipitation formation and are important in determining the Earth’s radiative budget. However, primary formation of ice in clouds is not fully understood. In the presence of ice nucleating particles (INPs), the phase change to ice is promoted, but identification and quantification of INPs in a natural environment remains challenging because of their low numbers. In this paper, we quantify INP number concentrations in the free troposphere (FT) as measured at the High Altitude Research Station Jungfraujoch (JFJ), during the winter, spring, and summer of the years 2014–2017. INPs were measured at conditions relevant for mixed-phase cloud formation at T = 241/242 K. To date, this is the longest timeline of semiregular measurements akin to online INP monitoring at this site and sampling conditions. We find that INP concentrations in the background FT are on average capped at 10/stdL (liter of air at standard conditions [T = 273 K and p = 1013 hPa]) with an interquartile range of 0.4–9.6/stdL, as compared to measurements during times when other air mass origins (e.g., Sahara or marine boundary layer) prevailed. Elevated concentrations were measured in the field campaigns of 2016, which might be due to enhanced influence from Saharan dust andmarine boundary layer air arriving at the JFJ. The upper limit of INP concentrations in the background FT is supported by measurements performed at similar conditions, but at different locations in the FT, where we find INP concentrations to be below 13/stdL most of the time.
121 citations
TL;DR: In this paper, the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites, was applied to 256 particulate matter (PM) filter samples (PM1, PM2, and PM10) collected at 16 urban and rural sites during summer and winter.
Abstract: . Field deployments of the Aerodyne Aerosol Mass Spectrometer (AMS) have significantly advanced real-time measurements and source apportionment of non-refractory particulate matter. However, the cost and complex maintenance requirements of the AMS make its deployment at sufficient sites to determine regional characteristics impractical. Furthermore, the negligible transmission efficiency of the AMS inlet for supermicron particles significantly limits the characterization of their chemical nature and contributing sources. In this study, we utilize the AMS to characterize the water-soluble organic fingerprint of ambient particles collected onto conventional quartz filters, which are routinely sampled at many air quality sites. The method was applied to 256 particulate matter (PM) filter samples (PM1, PM2.5, and PM10, i.e., PM with aerodynamic diameters smaller than 1, 2.5, and 10 µm, respectively), collected at 16 urban and rural sites during summer and winter. We show that the results obtained by the present technique compare well with those from co-located online measurements, e.g., AMS or Aerosol Chemical Speciation Monitor (ACSM). The bulk recoveries of organic aerosol (60–91 %) achieved using this technique, together with low detection limits (0.8 µg of organic aerosol on the analyzed filter fraction) allow its application to environmental samples. We will discuss the recovery variability of individual hydrocarbon ions, ions containing oxygen, and other ions. The performance of such data in source apportionment is assessed in comparison to ACSM data. Recoveries of organic components related to different sources as traffic, wood burning, and secondary organic aerosol are presented. This technique, while subjected to the limitations inherent to filter-based measurements (e.g., filter artifacts and limited time resolution) may be used to enhance the AMS capabilities in measuring size-fractionated, spatially resolved long-term data sets.
105 citations
Cites result from "Surface-to-mountaintop transport ch..."
...This is both in agreement with measurements at this site and also literature presenting measurements of background air masses (e.g. Griffiths et al., 2014, for Jungfraujoch)....
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TL;DR: The results show that bacteria survive and are metabolically active after the transport to the European Alps, and distinct differences in bacterial community composition and structure in SD-layers as compared to clean snow layers.
Abstract: Deposition of Sahara dust (SD) particles is a frequent phenomenon in Europe, but little is known about the viability and composition of the bacterial community transported with SD. The goal of this study was to characterize SD-associated bacteria transported to the European Alps, deposited and entrapped in snow. During two distinct events in February and May 2014, SD particles were deposited and promptly covered by falling snow, thus preserving them in distinct ochre layers within the snowpack. In June 2014, we collected samples at different depths from a snow profile at the Jungfraujoch (Swiss Alps; 3621 m a.s.l.). After filtration, we performed various microbiological and physicochemical analyses of the snow and dust particles therein that originated in Algeria. Our results show that bacteria survive and are metabolically active after the transport to the European Alps. Using high throughput sequencing, we observed distinct differences in bacterial community composition and structure in SD-layers as compared to clean snow layers. Sporulating bacteria were not enriched in the SD-layers; however, phyla with low abundance such as Gemmatimonadetes and Deinococcus-Thermus appeared to be specific bio-indicators for SD. Since many members of these phyla are known to be adapted to arid oligotrophic environments and UV radiation, they are well suited to survive the harsh conditions of long-range airborne transport.
73 citations
Cites background from "Surface-to-mountaintop transport ch..."
...High-altitude locations above the influence of the planetary boundary layer are ideal for detecting deposited Sahara dust (SD) particles because the potential contamination from anthropogenically-derived aerosols after deposition is minimal (Griffiths et al., 2014; Nicolás et al., 2014)....
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TL;DR: In this paper, six years of aerosol size distribution measurements between 20 and 600 nm diameters and total aerosol concentration above 10 µnm from March 2008 to February 2014 at the high-alpine site Jungfraujoch are presented.
Abstract: Six years of aerosol size distribution measurements between 20 and 600 nm diameters and total aerosol concentration above 10 nm from March 2008 to February 2014 at the high-alpine site Jungfraujoch are presented. The size distribution was found to be typically bimodal with mode diameters and widths relatively stable throughout the year and the observation period. New particle formation was observed on 14.5% of all days without a seasonal preference. Particles typically grew only into the Aitken mode and did not reach cloud condensation nucleus (CCN) sizes on the time scale of several days. Growth of preexisting particles in the Aitken mode, on average, contributed very few CCN. We concluded that the dominant fraction of CCN at Jungfraujoch originated in the boundary layer. A number of approaches were used to distinguish free tropospheric (FT) conditions and episodes with planetary boundary layer (PBL) influence. In the absence of PBL injections, the concentration of particles larger than 90 nm (N90, roughly corresponding to the CCN concentration) reached a value ~40 cm−3 while PBL influence caused N90 concentrations of several hundred or even 1000 cm−3. Comparing three criteria for free tropospheric conditions, we found FT prevalence for 39% of the time with over 60% during winter and below 20% during summer. It is noteworthy that a simple criterion based on standard trace gas measurements appeared to outperform alternative approaches.
67 citations
Cites background from "Surface-to-mountaintop transport ch..."
...Radon measurements at Jungfraujoch are discussed in Griffiths et al. [2014]....
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TL;DR: In this article, the atmospheric abundance of particles active as ice nuclei at −8°C (IN −8 ) over the course of a year at the high-alpine station Jungfraujoch (3580 m.a.s.l., Switzerland) through the use of immersion freezing assays of particles collected on quartz micro-fibre filters.
Abstract: The state of a slightly supercooled ephemeral cloud can be changed by the presence of a few particles capable of catalysing freezing, and potentially result in precipitation. We investigated the atmospheric abundance of particles active as ice nuclei at −8°C (IN −8 ) over the course of a year at the high-alpine station Jungfraujoch (3580 m.a.s.l., Switzerland) through the use of immersion freezing assays of particles collected on quartz micro-fibre filters. In addition, we determined IN −8 on a hill in the planetary boundary layer 95 km northwest of Jungfraujoch and in the dust laden Saharan Air Layer reaching Tenerife. Results indicate a strong seasonality of IN −8 at Jungfraujoch. Values were largest during summer (between 1 and 10 m −3 ) and about two orders of magnitude smaller during winter. Sahara dust events had a negligible influence on IN −8 at Jungfraujoch. Seasonality in the boundary layer was not observed in the upper, but in the lower bound of IN −8 values. Values<1 m −3 were only found on cold winter days, when IN −8 were more likely to have already been activated and deposited than on warmer days. A good correlation between IN −8 and maximum daily temperature at Jungfraujoch (R 2 =0.54) suggests IN −8 abundance at Jungfraujoch may be limited most of the year by microphysical processing related to IN activation in approaching air masses. Keywords: ice nuclei, slight supercooling, seasonal cycle, desert dust (Published: 5 February 2015) Citation: Tellus B 2015, 67, 25014, http://dx.doi.org/10.3402/tellusb.v67.25014
67 citations
Cites background from "Surface-to-mountaintop transport ch..."
...In other seasons, this upward transport of air from the boundary layer is less frequent and less intense (Lugauer et al., 1998; CollaudCoen et al., 2011; Griffiths et al., 2014)....
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References
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TL;DR: In this paper, the authors presented a European land-only daily high-resolution gridded data set for precipitation and minimum, maximum, and mean surface temperature for the period 1950-2006.
Abstract: We present a European land-only daily high-resolution gridded data set for precipitation and minimum, maximum, and mean surface temperature for the period 1950-2006. This data set improves on previous products in its spatial resolution and extent, time period, number of contributing stations, and attention to finding the most appropriate method for spatial interpolation of daily climate observations. The gridded data are delivered on four spatial resolutions to match the grids used in previous products as well as many of the rotated pole Regional Climate Models (RCMs) currently in use. Each data set has been designed to provide the best estimate of grid box averages rather than point values to enable direct comparison with RCMs. We employ a three-step process of interpolation, by first interpolating the monthly precipitation totals and monthly mean temperature using three-dimensional thin-plate splines, then interpolating the daily anomalies using indicator and universal kriging for precipitation and kriging with an external drift for temperature, then combining the monthly and daily estimates. Interpolation uncertainty is quantified by the provision of daily standard errors for every grid square. The daily uncertainty averaged across the entire region is shown to be largely dependent on the season and number of contributing observations. We examine the effect that interpolation has on the magnitude of the extremes in the observations by calculating areal reduction factors for daily maximum temperature and precipitation events with return periods up to 10 years. Copyright 2008 by the American Geophysical Union.
2,359 citations
"Surface-to-mountaintop transport ch..." refers background or methods in this paper
...In order to do this we take observed daily temperatures (the gridded E-OBS data (Haylock et al., 2008)), and extract a contingency table of daily maximum temperature anomalies depending on the classification according to radon and moisture, shown in Fig....
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...In order to do this we take observed daily temperatures, the gridded E-OBS data (Haylock et al., 2008), and extract a contingency table of daily maximum temperature anomalies depending on the classi605...
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TL;DR: The Mauna Loa Observatory has been used for eight years (1964-1971) of a long term program to document the effects of the combustion of coal, petroleum, and natural gas on the distribution of CO, in the atmosphere as mentioned in this paper.
Abstract: The concentration of atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii is reported for eight years (1964-1971) of a long term program to document the effects of the combustion of coal, petroleum, and natural gas on the distribution of CO, in the atmosphere. The new data, when combined with earlier data, indicate that the annual average CO, concentration rose 3.4 '% between 1959 and 1971. The rate of rise, however, has not been steady. In the mid-1960's it declined. Recently it has accelerated. Similar changes in rate have been observed at the South Pole and are evidently a global phenomenon.
667 citations
"Surface-to-mountaintop transport ch..." refers background in this paper
...These sites can be used to make measurements that are representative of continental to hemispheric scales (Keeling et al., 1976), also known as the baseline (Calvert, 1990; Parrish et al., 2014), by focusing on air masses which have travelled far from emission sources and had time to mix....
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Book•
15 May 2000
TL;DR: In this paper, the authors present an overview of applications of mountain meteorology in fire weather and smoke management, including aerial spraying, weather maps, forecasts and data, as well as selected applications of MMT.
Abstract: Preface About the author Acknowledgments PART 1. MOUNTAIN CLIMATES 1. Four factors that determine climate PART 2. AN INTRODUCTION TO THE ATMOSPHERE 2. Mountain climates of North America 3. Atmospheric scales of motion and atmospheric composition 4. Vertical structure, temperature, stability and the atmospheric boundary layer 5. Pressure and winds 6. Air masses and fronts 7. Clouds and fogs 8. Precipitation 9. Weather maps, forecasts and data PART 3. MOUNTAIN WINDS 10. Terrain-forced flows 11. Diurnal mountain winds PART 4. SELECTED APPLICATIONS OF MOUNTAIN METEOROLOGY 12. Air pollution dispersion 13. Fire weather and smoke management 14. Aerial spraying References Appendices Glossary Acronyms Abbreviations Index
640 citations
TL;DR: It is mentioned a more extensive use in climate studies, both of past, present, and future climates, innovative applications in the ensemble forecasting, increasing variety of synoptic–climatological investigations, and steps above from the troposphere.
Abstract: We review recent advances in classifications of circulation patterns as a specific research area within synoptic climatology. The review starts with a general description of goals of classification and the historical development in the field. We put circulation classifications into a broader context within climatology and systematize the varied methodologies and approaches. We characterize three basic groups of classifications: subjective (also called manual), mixed (hybrid), and objective (computer-assisted, automated). The roles of cluster analysis and principal component analysis in the classification process are clarified. Several recent methodological developments in circulation classifications are identified and briefly described: the introduction of nonlinear methods, objectivization of subjective catalogs, efforts to optimize classifications, the need for intercomparisons of classifications, and the progress toward an optimum, if possible unified, classification method. Among the recent tendencies in the applications of circulation classifications, we mention a more extensive use in climate studies, both of past, present, and future climates, innovative applications in the ensemble forecasting, increasing variety of synoptic-climatological investigations, and steps above from the troposphere. After introducing the international activity within the field of circulation classifications, the COST733 Action, we briefly describe outputs of the inventory of classifications in Europe, which was carried out within the Action. Approaches to the evaluation of classifications and their mutual comparisons are also reviewed. A considerable part of the review is devoted to three examples of applications of circulation classifications: in historical climatology, in analyses of recent climate variations, and in analyses of outputs from global climate models.
514 citations
TL;DR: In this paper, the Stochastic Time-Inverted Lagrangian Transport (STILT) model is used to determine surface fluxes from atmospheric concentration data in the midst of distributed sources or sinks over land, and illustrate the use of the tool with CO2 data over North America.
Abstract: [1] We introduce a tool to determine surface fluxes from atmospheric concentration data in the midst of distributed sources or sinks over land, the Stochastic Time-Inverted Lagrangian Transport (STILT) model, and illustrate the use of the tool with CO2 data over North America. Anthropogenic and biogenic emissions of trace gases at the surface cause large variations of atmospheric concentrations in the planetary boundary layer (PBL) from the “near field,” where upstream sources and sinks have strong influence on observations. Transport in the near field often takes place on scales not resolved by typical grid sizes in transport models. STILT provides the capability to represent near-field influences, transforming this noise to signal useful in diagnosing surface emissions. The model simulates transport by following the time evolution of a particle ensemble, interpolating meteorological fields to the subgrid scale location of each particle. Turbulent motions are represented by a Markov chain process. Significant computational savings are realized because the influence of upstream emissions at different times is modeled using a single particle simulation backward in time, starting at the receptor and sampling only the portion of the domain that influences the observations. We assess in detail the physical and numerical requirements of STILT and other particle models necessary to avoid inconsistencies and to preserve time symmetry (reversibility). We show that source regions derived from backward and forward time simulations in STILT are similar, and we show that deviations may be attributed to violation of mass conservation in currently available analyzed meterological fields. Using concepts from information theory, we show that the particle approach can provide significant gains in information compared to conventional gridcell models, principally during the first hours of transport backward in time, when PBL observations are strongly affected by surface sources and sinks.
463 citations