scholarly journals Aerobiology: Experimental Considerations, Observations, and Future Tools

2017 ◽  
Vol 83 (17) ◽  
Author(s):  
Allen E. Haddrell ◽  
Richard J. Thomas
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Transport ◽  
Method Comparison ◽  
Careful Consideration ◽  
Biological Processes ◽  
Single Droplet ◽  
Aerosol Generation ◽  
Research Fields ◽  
Molecular Microbiology ◽  
Modeling Techniques

ABSTRACT Understanding airborne survival and decay of microorganisms is important for a range of public health and biodefense applications, including epidemiological and risk analysis modeling. Techniques for experimental aerosol generation, retention in the aerosol phase, and sampling require careful consideration and understanding so that they are representative of the conditions the bioaerosol would experience in the environment. This review explores the current understanding of atmospheric transport in relation to advances and limitations of aerosol generation, maintenance in the aerosol phase, and sampling techniques. Potential tools for the future are examined at the interface between atmospheric chemistry, aerosol physics, and molecular microbiology where the heterogeneity and variability of aerosols can be explored at the single-droplet and single-microorganism levels within a bioaerosol. The review highlights the importance of method comparison and validation in bioaerosol research and the benefits that the application of novel techniques could bring to increasing the understanding of aerobiological phenomena in diverse research fields, particularly during the progression of atmospheric transport, where complex interdependent physicochemical and biological processes occur within bioaerosol particles.

scholarly journals Observation of liquid-liquid phase separation of ataxin-3 and quantitative evaluation of its concentration in a single droplet using Raman microscopy

2021 ◽  
Author(s):  
Kazuki Murakami ◽  
Shinji Kajimoto ◽  
Daiki Shibata ◽  
Kunisato Kuroi ◽  
Fumihiko Fujii ◽  
...  
Keyword(s):  
Phase Separation ◽  
Liquid Phase ◽  
Neurodegenerative Diseases ◽  
Protein Aggregation ◽  
Quantitative Evaluation ◽  
Raman Microscopy ◽  
Liquid Phase Separation ◽  
Biological Processes ◽  
Single Droplet ◽  
Liquid Liquid Phase Separation

Liquid–liquid phase separation (LLPS) plays an important role in a variety of biological processes and is also associated with protein aggregation in neurodegenerative diseases. Quantification of LLPS is necessary to...

Mobility and Solvation Structure of Hydroxyl Radical in a Water Nanodroplet: A Born-Oppenheimer Molecular Dynamics Study

2021 ◽  
Author(s):  
Mohammad Hadizadeh ◽  
Lewen Yang ◽  
Guoyong Fang ◽  
Zongyang Qiu ◽  
Zhenyu Li
Keyword(s):  
Molecular Dynamics ◽  
Hydroxyl Radical ◽  
Atmospheric Chemistry ◽  
Crucial Role ◽  
Biological Processes ◽  
Density Func Tional Theory ◽  
Condi Tions ◽  
Solvation Structure

Hydroxyl radical (OH*) plays a crucial role in atmospheric chemistry and biological processes. In this study, density func-tional theory (DFT)-based Born-Oppenheimer molecular dynamics (BOMD) simulations are performed under ambient condi-tions...

scholarly journals Technical Note: Feasibility of CO<sub>2</sub> profile retrieval from limb viewing solar occultation made by the ACE-FTS instrument

2009 ◽  
Vol 9 (8) ◽  
pp. 2873-2890 ◽  
Author(s):  
P. Y. Foucher ◽  
A. Chédin ◽  
G. Dufour ◽  
V. Capelle ◽  
C. D. Boone ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Transport ◽  
A Priori ◽  
Accurate Determination ◽  
Technical Note ◽  
High Spectral Resolution ◽  
Vertical Profiles ◽  
Vertical Resolution ◽  
Solar Occultation ◽  
Co2 Profile

Abstract. Major limitations of our present knowledge of the global distribution of CO2 in the atmosphere are the uncertainty in atmospheric transport mixing and the sparseness of in situ concentration measurements. Limb viewing space-borne sounders, observing the atmosphere along tangential optical paths, offer a vertical resolution of a few kilometers for profiles, which is much better than currently flying or planned nadir sounding instruments can achieve. In this paper, we analyse the feasibility of obtaining CO2 vertical profiles in the 5–25 km altitude range from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS, launched in August 2003), high spectral resolution solar occultation measurements. Two main difficulties must be overcome: (i) the accurate determination of the instrument pointing parameters (tangent heights) and pressure/temperature profiles independently from an a priori CO2 profile, and (ii) the potential impact of uncertainties in the temperature knowledge on the retrieved CO2 profile. The first difficulty has been solved using the N2 collision-induced continuum absorption near 4 μm to determine tangent heights, pressure and temperature from the ACE-FTS spectra. The second difficulty has been solved by a careful selection of CO2 spectral micro-windows. Retrievals using synthetic spectra made under realistic simulation conditions show a vertical resolution close to 2.5 km and accuracy of the order of 2 ppm after averaging over 25 profiles. These results open the way to promising studies of transport mechanisms and carbon fluxes from the ACE-FTS measurements. First CO2 vertical profiles retrieved from real ACE-FTS occultations shown in this paper confirm the robustness of the method and applicability to real measurements.

scholarly journals An online emission module for atmospheric chemistry transport models: implementation in COSMO-GHG v5.6a and COSMO-ART v5.1-3.1

2020 ◽  
Vol 13 (5) ◽  
pp. 2379-2392 ◽  
Author(s):  
Michael Jähn ◽  
Gerrit Kuhlmann ◽  
Qing Mu ◽  
Jean-Matthieu Haussaire ◽  
David Ochsner ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Transport ◽  
Model Simulation ◽  
Vertical Scaling ◽  
Transport Models ◽  
Input Size ◽  
Modeling Systems ◽  
Fortran 90 ◽  
Processing Steps ◽  
Python Package

Abstract. Emission inventories serve as crucial input for atmospheric chemistry transport models. To make them usable for a model simulation, they have to be pre-processed and, traditionally, provided as input files at discrete model time steps. In this paper, we present an “online” approach, which produces a minimal number of input data read-in at the beginning of a simulation and which handles essential processing steps online during the simulation. For this purpose, a stand-alone Python package “emiproc” was developed, which projects the inventory data to the model grid and generates temporal and vertical scaling profiles for individual emission categories. The package is also able to produce “offline” emission files if desired. Furthermore, we outline the concept of the online emission module (written in Fortran 90) and demonstrate its implementation in two different atmospheric transport models: COSMO-GHG and COSMO-ART. Simulation results from both modeling systems show the equivalence of the online and offline procedure. While the model run time is very similar for both approaches, input size and pre-processing time are greatly reduced when online emissions are utilized.

scholarly journals Non-volant modes of migration in terrestrial arthropods

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Don R. Reynolds ◽  
Andrew M. Reynolds ◽  
Jason W. Chapman
Keyword(s):  
Atmospheric Transport ◽  
Transport Processes ◽  
Biological Processes ◽  
Factors Affecting ◽  
Terrestrial Arthropods ◽  
Taxonomic Range ◽  
Migratory Movements ◽  
Dispersal Kernels ◽  
Typical Mode ◽  
Behavioural Adaptations

AbstractAnimal migration is often defined in terms appropriate only to the ‘to-and-fro’ movements of large, charismatic (and often vertebrate) species. However, like other important biological processes, the definition should apply over as broad a taxonomic range as possible in order to be intellectually satisfying. Here we illustrate the process of migration in insects and other terrestrial arthropods (e.g. arachnids, myriapods, and non-insect hexapods) but provide a different perspective by excluding the ‘typical’ mode of migration in insects, i.e. flapping flight. Instead, we review non-volant migratory movements, including: aerial migration by wingless species, pedestrian and waterborne migration, and phoresy. This reveals some fascinating and sometimes bizarre morphological and behavioural adaptations to facilitate movement. We also outline some innovative modelling approaches exploring the interactions between atmospheric transport processes and biological factors affecting the ‘dispersal kernels’ of wingless arthropods

scholarly journals Detecting changes in Arctic methane emissions: limitations of the inter-polar difference of atmospheric mole fractions

2018 ◽  
Vol 18 (24) ◽  
pp. 17895-17907 ◽  
Author(s):  
Oscar B. Dimdore-Miles ◽  
Paul I. Palmer ◽  
Lori P. Bruhwiler
Keyword(s):  
Mole Fraction ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Random Noise ◽  
The Arctic ◽  
Polar Regions ◽  
Annual Growth Rate ◽  
Continuous Version ◽  
The Antarctic

Abstract. We consider the utility of the annual inter-polar difference (IPD) as a metric for changes in Arctic emissions of methane (CH4). The IPD has been previously defined as the difference between weighted annual means of CH4 mole fraction data collected at stations from the two polar regions (defined as latitudes poleward of 53∘ N and 53∘ S, respectively). This subtraction approach (IPD) implicitly assumes that extra-polar CH4 emissions arrive within the same calendar year at both poles. We show using a continuous version of the IPD that the metric includes not only changes in Arctic emissions but also terms that represent atmospheric transport of air masses from lower latitudes to the polar regions. We show the importance of these atmospheric transport terms in understanding the IPD using idealized numerical experiments with the TM5 global 3-D atmospheric chemistry transport model that is run from 1980 to 2010. A northern mid-latitude pulse in January 1990, which increases prior emission distributions, arrives at the Arctic with a higher mole fraction and ≃12 months earlier than at the Antarctic. The perturbation at the poles subsequently decays with an e-folding lifetime of ≃4 years. A similarly timed pulse emitted from the tropics arrives with a higher value at the Antarctic ≃11 months earlier than at the Arctic. This perturbation decays with an e-folding lifetime of ≃7 years. These simulations demonstrate that the assumption of symmetric transport of extra-polar emissions to the poles is not realistic, resulting in considerable IPD variations due to variations in emissions and atmospheric transport. We assess how well the annual IPD can detect a constant annual growth rate of Arctic emissions for three scenarios, 0.5 %, 1 %, and 2 %, superimposed on signals from lower latitudes, including random noise. We find that it can take up to 16 years to detect the smallest prescribed trend in Arctic emissions at the 95 % confidence level. Scenarios with higher, but likely unrealistic, growth in Arctic emissions are detected in less than a decade. We argue that a more reliable measurement-driven approach would require data collected from all latitudes, emphasizing the importance of maintaining a global monitoring network to observe decadal changes in atmospheric greenhouse gases.

scholarly journals Regional pollution potentials of megacities and other major population centers

2007 ◽  
Vol 7 (14) ◽  
pp. 3969-3987 ◽  
Author(s):  
M. G. Lawrence ◽  
T. M. Butler ◽  
J. Steinkamp ◽  
B. R. Gurjar ◽  
J. Lelieveld
Keyword(s):  
Long Range ◽  
Atmospheric Chemistry ◽  
Atmospheric Transport ◽  
Deep Convection ◽  
Vertical Mixing ◽  
Geographical Location ◽  
Point Sources ◽  
High Latitudes ◽  
Near Surface ◽  
Regional Pollution

Abstract. Megacities and other major population centers represent large, concentrated sources of anthropogenic pollutants to the atmosphere, with consequences for both local air quality and for regional and global atmospheric chemistry. The tradeoffs between the regional buildup of pollutants near their sources versus long-range export depend on meteorological characteristics which vary as a function of geographical location and season. Both horizontal and vertical transport contribute to pollutant export, and the overall degree of export is strongly governed by the lifetimes of pollutants. We provide a first quantification of these tradeoffs and the main factors influencing them in terms of "regional pollution potentials", metrics based on simulations of representative tracers using the 3-D global model MATCH (Model of Atmospheric Transport and Chemistry). The tracers have three different lifetimes (1, 10, and 100 days) and are emitted from 36 continental large point sources. Several key features of the export characteristics emerge. For instance, long-range near-surface pollutant export is generally strongest in the middle and high latitudes, especially for source locations in Eurasia, for which 17–34% of a tracer with a 10-day lifetime is exported beyond 1000 km and still remains below 1 km altitude. On the other hand, pollutant export to the upper troposphere is greatest in the tropics, due to transport by deep convection, and for six source locations, more than 50% of the total mass of the 10-day lifetime tracer is found above 5 km altitude. Furthermore, not only are there order of magnitude interregional differences, such as between low and high latitudes, but also often substantial intraregional differences, which we discuss in light of the regional meteorological characteristics. We also contrast the roles of horizontal dilution and vertical mixing in reducing the pollution buildup in the regions including and surrounding the sources. For some regions such as Eurasia, dilution due to long-range horizontal transport governs the local and regional pollution buildup; however, on a global basis, differences in vertical mixing are dominant in determining the pollution buildup both around and further downwind of the source locations.

On the Synergistic Climatic Effects of Covarying Major Mountain Range Topographies

2020 ◽  
Author(s):  
Sebastian G. Mutz ◽  
Todd A. Ehlers
Keyword(s):  
General Circulation ◽  
Atmospheric Transport ◽  
Circulation Model ◽  
Careful Consideration ◽  
Mountain Range ◽  
Earth Surface ◽  
Climatic Effects ◽  
Climate Conditions ◽  
Mountain Ranges ◽  
The Impact

&lt;p&gt;The interpretation of Earth surface archives often requires consideration of distant off-site events. One such event is the surface uplift of Earth&amp;#8217;s major mountain ranges, which affects climate and the Earth&amp;#8217;s surface globally. In this study, the individual and synergistic climatic effects of topographic changes in major mountain ranges are explored with a series of General Circulation Model (GCM) experiments and analyses of atmospheric teleconnections. The GCM experiments are forced with different topographic scenarios for Himalaya-Tibet (TBT) and the Andes (ADS), while environmental boundary conditions are kept constant. The topographic scenarios are constructed by successively lowering modern topography to 0% of its modern height in increments of 25%. This results in a total of 5 topographic scenarios for TBT (tbt100, tbt075, tbt050, tbt025, tbt000) and ADS (ads100, ads075, ads050, ads025, ads000). TBT scenarios are then nested in ADS scenarios, resulting in a total of 25 experiments with unique topographic settings. The climate for each of those 25 scenarios is simulated with the GCM ECHAM5-wiso. We then explore possible synergies and distant impacts of topographic changes by testing the hypothesis that varying ADS has no effect on simulated climate conditions in the TBT region (c_tbt) and vice versa. This can be expressed as the null hypothesis c_tbt(ads100) = c_tbt(ads075) = c_tbt(ads050) = c_tbt(ads025) = c_tbt(ads000) for each of the 5 TBT scenarios, and vice versa. We conduct Kruskal-Wallis tests for a total of 10 treatment sets to address these hypotheses. The results suggest that ADS climate is mostly independent of TBT topography changes, whereas TBT climate is sensitive to ADS topography changes when TBT topography is high, but insensitive when TBT topography is strongly reduced. Analyses of atmospheric pressure fields suggest that TBT height acts as a control on cross-equatorial atmospheric transport and modifies the impact of ADS topography on northern hemisphere climate. These results dictate a more careful consideration of global (off-site) conditions in the interpretation of Earth surface records.&lt;/p&gt;

scholarly journals Brominated VSLS and their influence on ozone under a changing climate

2017 ◽  
Vol 17 (18) ◽  
pp. 11313-11329 ◽  
Author(s):  
Stefanie Falk ◽  
Björn-Martin Sinnhuber ◽  
Gisèle Krysztofiak ◽  
Patrick Jöckel ◽  
Phoebe Graf ◽  
...  
Keyword(s):  
21St Century ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Atmospheric Transport ◽  
Stratospheric Ozone ◽  
Chemical Transformations ◽  
Mixing Ratios ◽  
Ocean Atmosphere ◽  
The Impact

Abstract. Very short-lived substances (VSLS) contribute as source gases significantly to the tropospheric and stratospheric bromine loading. At present, an estimated 25 % of stratospheric bromine is of oceanic origin. In this study, we investigate how climate change may impact the ocean–atmosphere flux of brominated VSLS, their atmospheric transport, and chemical transformations and evaluate how these changes will affect stratospheric ozone over the 21st century. Under the assumption of fixed ocean water concentrations and RCP6.0 scenario, we find an increase of the ocean–atmosphere flux of brominated VSLS of about 8–10 % by the end of the 21st century compared to present day. A decrease in the tropospheric mixing ratios of VSLS and an increase in the lower stratosphere are attributed to changes in atmospheric chemistry and transport. Our model simulations reveal that this increase is counteracted by a corresponding reduction of inorganic bromine. Therefore the total amount of bromine from VSLS in the stratosphere will not be changed by an increase in upwelling. Part of the increase of VSLS in the tropical lower stratosphere results from an increase in the corresponding tropopause height. As the depletion of stratospheric ozone due to bromine depends also on the availability of chlorine, we find the impact of bromine on stratospheric ozone at the end of the 21st century reduced compared to present day. Thus, these studies highlight the different factors influencing the role of brominated VSLS in a future climate.

scholarly journals Mesosphere-to-stratosphere descent of odd nitrogen in February–March 2009 after sudden stratospheric warming

2011 ◽  
Vol 11 (1) ◽  
pp. 1429-1455 ◽  
Author(s):  
S.-M. Salmi ◽  
P. T. Verronen ◽  
L. Thölix ◽  
E. Kyrölä ◽  
L. Backman ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Good Opportunity ◽  
Weather Forecasts ◽  
Model Study ◽  
Halogen Chemistry ◽  
Odd Nitrogen ◽  
Chemistry Experiment

Abstract. We use the 3-D FinROSE chemistry transport model (CTM) and ACE-FTS (Atmospheric Chemistry Experiment Fourier Transform Spectrometer) observations to study the connection between atmospheric dynamics and NOx descent during early 2009 in the northern polar region. We force the model NOx at 80 km poleward of 60° N with ACE-FTS observations and then compare the model results with observations at lower altitudes. Low geomagnetic indices indicate absence of local NOx production in early 2009, which gives a good opportunity to study the effects of atmospheric transport on polar NOx. No in-situ production of NOx by energetic particle precipitation is therefore included. This is the first model study using ECMWF (The European Centre for Medium-Range Weather Forecasts) data up to 80 km and simulating the exceptional winter of 2009 with one of the strongest major sudden stratospheric warmings (SSW). The model results show a strong NOx descent in February–March 2009 from the upper mesosphere to the stratosphere after the major SSW. Both observations and model results suggest an increase of NOx to 150–200 ppb (i.e. by factor of 50) at 65 km due to the descent following the SSW. The model, however, underestimates the amount of NOx around 55 km by 40–60 ppb. The results also show that the chemical loss of NOx was insignificant i.e. NOx was mainly controlled by the dynamics. Both ACE-FTS observations and FinROSE show a decrease of ozone of 20–30% at 30–50 km after mid-February to mid-March. However, these changes are not related to the NOx descent, but are due to activation of the halogen chemistry.

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