Long-range Transport Model Research Articles

Air Pollution Modeling of UNI-DEM Model by using Innovative Stochastic Approaches

In this paper we develop advanced multidimensional sensitivity analysis, based on some innovative stochastic approaches for performing air pollution modelling on a large-scale model of long-range transport of air pollutants. The Unified Danish Eulerian Model (UNI-DEM) is a very important mathematical model, and can be applied in many different studies related to damaging effects caused by high air pollution levels. We shall use it in this paper to get a reliable answer to a some very important questions regrading environmental protection. We develop some advanced Monte Carlo and quasi-Monte Carlo methods, based on special lattice and digital sequences. In this paper we will improve the digital ecosystem modeling by improving the existence stochastic approaches. The computational efficiency (in terms of relative error and computational time) of the advanced Monte Carlo algorithms for multidimensional numerical integration has been studied to analyze the sensitivity of UNI-DEM model output to variation of input emissions of the anthropogenic pollutants and of rates of several chemical reactions. The algorithms will be applied to compute global Sobol sensitivity measures corresponding to the influence of several input parameters on the concentrations of important air pollutants. The study will be done for the areas of several European cities with different geographical locations.

210Pb Deposition Distribution in the Northern Hemisphere Based on a Long-Range Atmospheric Transport and Deposition Model Calculation

This study delves into the long-term atmospheric transport and deposition of 210Pb in the Northern Hemisphere by using the atmospheric transport model HIRAT. The calculation for the four-year (2012–2015) period showed an average deposition flux of 13.0 Bq m−2 month−1 with significant seasonal variations characterized by higher deposition rates during summer and lower during winter. High deposition was found in the Northern Bay of Bengal and Bangladesh regions, Southern China, the Western Philippine Sea, the Eastern Japan Sea, the Northwestern Pacific region, the Eastern and Western coasts of North America, the Caribbean Sea, the Eastern Pacific region off of Central America, the Central Atlantic region between Central America and Africa, and the Northwestern Atlantic Ocean. Deposition patterns varied across latitudinal zones, with tropical areas experiencing the highest deposition and polar/subpolar zones the lowest. This study emphasized the impact of monsoons on the significantly large 210Pb deposition in the Japan Sea region. Furthermore, this study showed that the lower troposphere (0 to 3 km) dominates with about 53%, and the middle troposphere (3 to 6 km) and upper troposphere (above 6 km) also contribute significantly to the total 210Pb inventory with 37% and 10%, respectively. These findings provide essential insights into the characteristics of atmospheric transport and deposition of 210Pb, and their mechanisms.

Contribution of the Collective Excitations to the Coupled Proton and Energy Transport along Mitochondrial Cristae Membrane in Oxidative Phosphorylation System.

The results of many experimental and theoretical works indicate that after transport of protons across the mitochondrial inner membrane (MIM) in the oxidative phosphorylation (OXPHOS) system, they are retained on the membrane-water interface in nonequilibrium state with free energy excess due to low proton surface-to-bulk release. This well-established phenomenon suggests that proton trapping on the membrane interface ensures vectorial lateral transport of protons from proton pumps to ATP synthases (proton acceptors). Despite the key role of the proton transport in bioenergetics, the molecular mechanism of proton transfer in the OXPHOS system is not yet completely established. Here, we developed a dynamics model of long-range transport of energized protons along the MIM accompanied by collective excitation of localized waves propagating on the membrane surface. Our model is based on the new data on the macromolecular organization of the OXPHOS system showing the well-ordered structure of respirasomes and ATP synthases on the cristae membrane folds. We developed a two-component dynamics model of the proton transport considering two coupled subsystems: the ordered hydrogen bond (HB) chain of water molecules and lipid headgroups of MIM. We analytically obtained a two-component soliton solution in this model, which describes the motion of the proton kink, corresponding to successive proton hops in the HB chain, and coherent motion of a compression soliton in the chain of lipid headgroups. The local deformation in a soliton range facilitates proton jumps due to water molecules approaching each other in the HB chain. We suggested that the proton-conducting structures formed along the cristae membrane surface promote direct lateral proton transfer in the OXPHOS system. Collective excitations at the water-membrane interface in a form of two-component soliton ensure the coupled non-dissipative transport of charge carriers and elastic energy of MIM deformation to ATP synthases that may be utilized in ATP synthesis providing maximal efficiency in mitochondrial bioenergetics.

LONG-RANGE ATMOSPHERIC TRANSPORT OF RADON IN EAST ASIA AND DEPOSITION OF ITS PROGENIES IN JAPAN.

A three-dimensional long-range atmospheric transport model for 222Rn and its progenies was applied to simulate 210Pb deposition in Japan and its adjacent waters. Monthly precipitation and 210Pb deposition simulated by the model for winter months were favorably compared with observational data although they were exceptionally underestimated in Aomori. The large monthly deposition along the Japan Sea coast lines during winter was successfully simulated by the model to be nearly 200Bqm-2, which was contrasted by about 10-fold smaller deposition in other regions. It was also pointed out that the heavy deposition areas formed a narrow band structure along the coastline with width of several tens of kilometers and 210Pb deposition amount positively correlated with the height of mountains located leeward of the heavy deposition areas.

Statistical approach to assess radon-222 long-range atmospheric transport modelling and its associated gamma dose rate peaks

Abstract. There is a need for a validation framework for long-range atmospheric transport modelling dedicated to radionuclides. For distances greater than 50 km, the modelling of radionuclide deposition and ambient gamma dose rate evaluation are particularly difficult to validate, since it has been mainly only observed after the accidents of Chernobyl and Fukushima. There is however a natural wet deposition phenomenon leading to numerous well-observed gamma dose rate events: the scavenging of radon-222 progeny by rain. Radon-222 exhalation from the soil to the atmosphere, its decay, its progeny, its own transport, the transport of its progeny, their deposition, and the consequent ambient gamma dose rate are then modelled at the European scale. This whole atmospheric radon model from soil (exhalation) to soil (deposition) needs to be validated by comparison with observations. The biggest benefit of this case study is the number of events that serve as a comparison. For a statistical evaluation of the performance of the model, we compared its results with gamma dose rate observations over a period of two years, gathering more than 15 000 peaks greater than 10 nSv h−1 above the background radiation. Two sets of metrics were used to assess the agreement between the model and observations: on a case by case basis (peak to peak) and continuously (whole time series of gamma dose rates and air concentrations). Particular attention was paid to defining the metrics in order to remove the background radiation level and to exclude outlier stations. We found that 48 % of the gamma dose rate peaks are well modelled, a fraction of which can rise up to 89 % by being more tolerant with the success criteria. The model has proven to be of the correct magnitude, with room for substantial improvement. Overall, the modelling shows better recall than precision: i.e. a tendency to produce more false positives than false negatives. It is also less effective in reproducing the highest peaks. Exhalation, vertical mixing and deposition have been identified as the three main features which could improve this model. Now validated, with all its limitations, the atmospheric radon model may serve for its primary purpose, the validation of atmospheric transport modelling and its input data. It also may serve as a framework to test any exhalation model on a national or continental scale. Moreover, it is useful to learn how to properly use the data of an ambient gamma dose rate network, and how to compare this data to modelled data. Finally, some interesting features concerning the assessment of outdoor concentrations of radon-222 became apparent.

Modelling mercury concentration in Ghanaian soil

Mercury usage in Artisanal Small Scale Gold Mining is a major anthropogenic source of mercury in the environment. In this study, mercury pools and fluxes have been established for Ghana, which has a large ASGM sector, based on estimated losses of mercury to the environment, deposition calculated with GLEMOS, a global long-range transport model for mercury in air, and mercury measured in soils and water in Ghana. A model for mercury in soils and water of Ghana with a resolution of 5 × 5 km2 and a monthly or yearly time step has been developed to assess the regional increase in soil and water concentrations that can be attributed to anthropogenic sources and to simulate scenarios into the future. The model has been calibrated to reproduce present-day mercury concentration in the soil (average 0.0193 mg kg−1) with current deposition calculated with the long-range transport model and past years’ deposition based on a scenario for the historic development of the mining activity. This calculation gives an average increase in soil concentrations from anthropogenic sources of 22%. The model gives a fair description of the regional differences in soil concentrations but underestimates concentrations in regions with intense mining activity and overestimates concentrations in regions with less mining when using deposition from the long-range model as input.

Trend analysis of reduced nitrogen components over the Netherlands with the EMEP4NL and OPS model

Declining ammonia emissions are not always reflected in ammonia concentrations due to physicochemical processes and meteorology. Here we present a trend analysis of reduced nitrogen components over the Netherlands using two different types of atmospheric transport models: the Eulerian grid model EMEP/MSC-W and the plume model OPS.We employ calculations with the Eulerian grid model EMEP/MSC-W for the Netherlands in its EMEP4NL configuration. Using the Weather Research Forecast (WRF) model as meteorological driver plus detailed emission data over the Netherlands as input into the EMEP4NL model, we present simulation results over the Netherlands of reduced nitrogen components from this model at a horizontal resolution of 1.3 × 2.1 km.Using this configuration of the EMEP/MSC-W model (EMEP4NL), a trend analysis is performed over the period 2006–2015 for concentration and deposition of reduced nitrogen components over the Netherlands. The same analysis is performed with the OPS-model, a plume model with a Lagrangian trajectory model for long range transport. Both models use the same MACC III emission distribution for countries outside of the Netherlands, and spatially more detailed emissions for the Netherlands itself. Emission totals per SNAP (Supporting National Action and Planning) sector per country are used over the period 2006–2015, according to the latest CEIP (Centre on Emissions Inventories and Projections) expert estimates. The OPS-model is driven with yearly specific meteorological fields provided by the Royal Netherlands Meteorological Institute (KNMI). Furthermore, the OPS-model parameterizes its chemistry, whereas EMEP4NL uses a state-of-the-art chemistry scheme.Results from ammonia concentrations, ammonium concentrations and wet deposition as calculated with both models, are first compared with observations from the National Air Quality Monitoring Network in the Netherland (LML). Calculations of ammonia and wet deposition both agree well with the measurements in the OPS and the EMEP4NL model. Ammonium is better represented by calculations with the EMEP4NL model than by the OPS-model. Measurements of dry deposition of reduced nitrogen are very limited, therefore only a comparison is made between the model results of EMEP4NL and OPS.Subsequently, a trend analysis is performed over the period 2006–2015 for the reduced nitrogen components for both model calculation results and the measurements. The trends of all components are calculated over the mean values of monitoring stations over the Netherlands. The reported decline in the emissions of ammonia is not reflected in the ammonia concentrations and wet deposition of reduced nitrogen as measured and calculated with the OPS and the EMEP4NL model. Ammonium concentrations on the other hand are declining (also) due to the decrease of the SOx emissions over the period 2006–2015. Finally, both models show a slight decline in the dry deposition values, despite the fact that both models (and observations) do not show a decrease in the ammonia concentrations. A more detailed analysis of the comparison of dry deposition of reduced nitrogen between both models, and the influence of the physicochemical processes and meteorology is in preparation. Overall, it is found that the calculated trends for the different reduced nitrogen components with a grid model like EMEP4NL and a plume model like OPS are roughly in line with each other.

Dopamine Transporter Localization in Medial Forebrain Bundle Axons Indicates Its Long-Range Transport Primarily by Membrane Diffusion with a Limited Contribution of Vesicular Traffic on Retromer-Positive Compartments.

Dopamine transporter (DAT) controls dopamine neurotransmission by clearing synaptically released dopamine. However, trafficking itineraries of DAT, which determine its cell-surface concentration near synapses, are poorly characterized. It is especially unknown how DAT is transported between spatially distant midbrain somatodendritic and striatal axonal compartments. To examine this "long-range" trafficking, the localization and membrane diffusion of HA-epitope tagged DAT in the medial forebrain bundle (MFB) of a knock-in mouse (both sexes) were analyzed using confocal, super-resolution and EM in intact brain and acute brain slices. HA-DAT was abundant in the plasma membrane of MFB axons, similar to the striatum, although the intracellular fraction of HA-DAT in MFB was more substantial. Intracellular HA-DAT colocalized with VPS35, a subunit of the retromer complex mediating recycling from endosomes, in a subset of axons. Late endosomes, lysosomes, and endoplasmic reticulum were abundant in the soma but minimally present in MFB axons, suggesting that biosynthesis and lysosomal degradation of DAT are confined to soma. Together, the data suggest that membrane diffusion is the main mode of long-range DAT transport through MFB, although the contribution of vesicular traffic can be significant in a population of MFB axons. Based on HA-DAT diffusion rates, plasma membrane DAT in MFB axons turns over with a halftime of ∼20 d, which explains the extremely slow turnover of DAT protein in the brain. Unexpectedly, the mean diameter of DAT-labeled MFB axons was observed to be twice larger than reported for striatum. The implications of this finding for dopamine neuron physiology are discussed.SIGNIFICANCE STATEMENT The dopamine transporter (DAT) is a key regulator of dopamine neurotransmission and a target of abused psychostimulants. In the present study, we examined, for the first time, mechanisms of the long-range traffic of DAT in intact brain and acute brain slices from the knock-in mouse expressing epitope-tagged DAT. Using a combination of confocal, super-resolution and EM, we defined DAT localization and its membrane diffusion parameters in medial forebrain bundle axonal tracts connecting midbrain somatodendritic and striatal axonal compartments of dopaminergic neurons. In contrast to the widely accepted model of long-range axonal transport, our studies suggest that DAT traffics between midbrain and striatum, mainly by lateral diffusion in the plasma membrane with only a limited contribution of vesicular transport in recycling endosomes.

Study of Fuel-Smoke Dynamics in a Prescribed Fire of Boreal Black Spruce Forest through Field-Deployable Micro Sensor Systems

Understanding the combustion dynamics of fuels, and the generation and propagation of smoke in a wildland fire, can inform short-range and long-range pollutant transport models, and help address and mitigate air quality concerns in communities. Smoldering smoke can cause health issues in nearby valley bottoms, and can create hazardous road conditions due to low-visibility. We studied near-field smoke dynamics in a prescribed fire of 3.4 hectares of land in a boreal black spruce forest in central Alberta. Smoke generated from the fire was monitored through a network of five field-deployable micro sensor systems. Sensors were placed within 500–1000 m of the fire area at various angles in downwind. Smoke generated from flaming and smoldering combustions showed distinct characteristics. The propagation rates of flaming and smoldering smoke, based on the fine particulate (PM2.5) component, were 0.8 and 0.2 m/s, respectively. The flaming smoke was characterized by sharp rise of PM2.5 in air with concentrations of up to 940 µg/m3, followed by an exponential decay with a half-life of ~10 min. Smoldering combustion related smoke contributed to PM2.5 concentrations above 1000 µg/m3 with slower decay half-life of ~18 min. PM2.5 emissions from the burn area during flaming and smoldering phases, integrated over the combustion duration of 2.5 h, were ~15 and ~16 kilograms, respectively, as estimated by our mass balance model.

Snow Samples Combined With Long-Range Transport Modeling to Reveal the Origin and Temporal Variability of Black Carbon in Seasonal Snow in Sodankylä (67°N)

In the Arctic areas, the influence of global climate change is enhanced. Enabling a better understanding of the changes in the Arctic environment is of the utmost importance. The deposition of local and long-range transported air pollutants includes light-absorbing aerosols, such as black carbon (BC), which darken bright surfaces and induce snow melt. In 2009–2013, surface snow was sampled on a weekly basis during autumn, winter and spring at the Arctic Space Centre of the Finnish Meteorological Institute in Sodankylä, which is located north of the Arctic Circle (67.37o N, 26.63o E). Snow samples were analyzed for BC with an Organic/Elemental Carbon Aerosol (OCEC) analyzer. These data were combined with SILAM modeling (System for Integrated modeLing of Atmospheric coMposition) to reveal the origin and temporal variability of BC in seasonal snow. Quantitative footprint calculations for the BC observations were performed with the SILAM -model considering emission sources at all heights and including also the sensitivity to the local and near-surface sources. The median BC concentration in snow was 25 µg/kg (n = 107, skewness γ1 = 0.12, 75th percentile Q3 = 42 µg/kg), determined as [μg-EC/L-H2O]. During snow accumulation season, the median surface snow BC concentration was 21µg/kg (n = 78, γ1 = 1.5, Q3 = 33 µg/kg), and during melt season, it was 57 µg/kg (n = 29, γ1 = 2.2, Q3 = 85 µg/kg). The melt period was identified using snow depth data from the Sodankylä station. The highest BC values in spring represented the enrichment of BC to the snow surface due to seasonal snow melt. The spring melt BC enrichment ratio was 2.7 (calculated as the ratio of median melt season concentration to median accumulation season snow concentration). The results showed that increased surface snow BC concentrations (> 30 µg/kg) were due to air masses originating from the Murmansk region in Russia, where smelting and mining industries are located. The temporal variability of BC in snow was high and depended on atmospheric and cryospheric processes, mostly the origin of BC due to atmospheric transport and dry and wet deposition processes, as well as post-depositional snow processes.

Estimating the contamination resulting from hypothetical nuclear accidents during nuclear emergency exercises

An assessment of the radiological contamination of Europe, following radioactive pollutant releases and using prognostic meteorological data is presented. A modified and simplified version of SHEAR code, a Lagrangian long-range transport and dispersion model, taking into account the wind shear effect, is used. This is possible by applying the diurnal differences in vertical mixing to the winds in the vertical layer used to calculate advection. In its present version the code takes account of dry deposition processes and different mixing heights for day and night conditions. Prognostic temperature and u, ν wind parameters every 6 hours for a total of 72, are provided by the National Meteorological Service of Greece in two levels 0 and 850 mb of pressure. The wind field is then calculated in both heights. This field forms an input to the SHEAR code. Plume direction and radioactive pollutant concentration have been calculated for hypothetical releases postulated during a recent ΝΕΑ/OECD exercise. The results of this study indicated that the code predicted well direction and concentration of the plume, in agreement with the predictions by other programs. Since the code in this version uses surface winds, at most, which are much weaker than the higher altitude winds used by other codes, the results of the plume spread are smaller in the present study. We believe that taking into account the surface winds during an eventual accident produces more realistic results. If predictions in more heights are available mixing heights would be calculated with greater accuracy, with consequent improvement of the results.

Formation of Polycyclic Aromatic Hydrocarbon Oxidation Products in α-Pinene Secondary Organic Aerosol Particles Formed through Ozonolysis.

Accurate long-range atmospheric transport (LRAT) modeling of polycyclic aromatic hydrocarbons (PAHs) and PAH oxidation products (PAH-OPs) in secondary organic aerosol (SOA) particles relies on the known chemical composition of the particles. Four PAHs, phenanthrene (PHE), dibenzothiophene (DBT), pyrene (PYR), and benz(a)anthracene (BaA), were studied individually to identify and quantify PAH-OPs produced and incorporated into SOA particles formed by ozonolysis of α-pinene in the presence of PAH vapor. SOA particles were characterized using real-time in situ instrumentation, and collected on quartz fiber filters for offline analysis of PAHs and PAH-OPs. PAH-OPs were measured in all PAH experiments at equal or greater concentrations than the individual PAHs they were produced from. The total mass of PAH and PAH-OPs, relative to the total SOA mass, varied for different experiments on individual parent PAHs: PHE and 6 quantified PHE-OPs (3.0%), DBT and dibenzothiophene sulfone (4.9%), PYR and 3 quantified PYR-OPs (3.1%), and BaA and benz(a)anthracene-7,12-dione (0.26%). Further exposure of PAH-SOA to ozone generally increased the concentration ratio of PAH-OPs to PAH, suggesting longer atmospheric lifetimes for PAH-OPs, relative to PAHs. These data indicate that PAH-OPs are formed during SOA particle formation and growth.

Simulated Dispersion of the Gas Released by the SpaceX Falcon9 Rocket Explosion

This Paper provides a qualitative analysis of the contaminant dispersion caused by the SpaceX Falcon 9 rocket accident at Cape Canaveral Air Force Station on 1 September 2016. To achieve this, the Model for Simulating Rocket Exhaust Dispersion and its modeling system were applied to simulate the dispersion of the contaminants emitted during the explosion of the Falcon 9 rocket. This modeling system is a modern tool for risk management and environmental analysis for the evaluation of normal and aborted rocket launch events, being also suitable for the assessment of explosion cases. It deals with the representation of the source term (formation, rising, expansion, and stabilization of the exhaust cloud), the simulation of the short-range dispersion (in the scale from minutes to a couple of hours), and the long-range and chemical transport modeling by integrating with the Community Multiscale Air Quality model and reading meteorological input data from the Weather Research and Forecast model. The results showed that the modeling system captured satisfactorily the phenomenon inside the planetary boundary layer.

Assessment of winter air pollution episodes using long-range transport modeling in Hangzhou, China, during World Internet Conference, 2015

A winter air pollution episode was observed in Hangzhou, South China, during the Second World Internet Conference, 2015. To study the pollution characteristics and underlying causes, the Weather Research and Forecasting with Chemistry model was used to simulate the spatial and temporal evolution of the pollution episode from December 8 to 19, 2015. In addition to scenario simulations, analysis of the atmospheric trajectory and synoptic weather conditions were also performed. The results demonstrated that control measures implemented during the week preceding the conference reduced the fine particulate matter (PM2.5) pollution level to some extent, with a decline in the total PM2.5 concentration in Hangzhou of 15% (7%-25% daily). Pollutant long-range transport, which occurred due to a southward intrusion of strong cold air driven by the Siberia High, led to severe pollution in Hangzhou on December 15, 2015, accounting for 85% of the PM2.5 concentration. This study provides new insights into the challenge of winter pollution prevention in Hangzhou. For adequate pollution prevention, more regional collaborations should be fostered when creating policies for northern China.

Assessment of the announced North Korean nuclear test using long-range atmospheric transport and dispersion modelling

On 6 January 2016, the Democratic People’s Republic of Korea announced to have conducted its fourth nuclear test. Analysis of the corresponding seismic waves from the Punggye-ri nuclear test site showed indeed that an underground man-made explosion took place, although the nuclear origin of the explosion needs confirmation. Seven weeks after the announced nuclear test, radioactive xenon was observed in Japan by a noble gas measurement station of the International Monitoring System. In this paper, atmospheric transport modelling is used to show that the measured radioactive xenon is compatible with a delayed release from the Punggye-ri nuclear test site. An uncertainty quantification on the modelling results is given by using the ensemble method. The latter is important for policy makers and helps advance data fusion, where different nuclear Test-Ban-Treaty monitoring techniques are combined.

The theory of long-range Josephson current through a single-crystal ferromagnet nanowire

Theoretical model of the singlet long-range Josephson transport is proposed. Taking into account the mismatch of the electron effective masses of majority and minority spin subbands the Eilenberger-like equations are obtained with renormalized effective exchange interaction. The critical Josephson current is calculated through ferromagnet nanowire. It is shown that the effective exchange field can be completely compensated and thereby the long-range spatial supercurrent arises. Within the proposed theoretical model, the long-range proximity effect observed in the Co single-crystalline nanowire (Wang et al., 2010) can be qualitatively understood.

Remote sensing observations for monitoring and mathematical simulations of transboundary air pollutants migration from Siberian mass wildfires to Kazakhstan

Anthropogenic and natural factors have increased the power of wildfires in massive Siberian woodlands. As a consequence, the expansion of burned areas and increase in the duration of the forest fire season have led to the release of significant amounts of gases and aerosols. Therefore, it is important to understand the impact of wildland fires on air quality, atmospheric composition, climate and accurately describe the distribution of combustion products in time and space. The most effective research tool is the regional hydrodynamic model of the atmosphere, coupled with the model of pollutants transport and chemical interaction. Taking into account the meteorological parameters and processes of chemical interaction of impurities, complex use of remote sensing techniques for monitoring massive forest fires and mathematical modeling of long-range transport of pollutants in the atmosphere, allow to evaluate spatial and temporal scale of the phenomenon and calculate the quantitative characteristics of pollutants depending on the height and distance of migration.

Dynamic model for kinesin-mediated long-range transport and its local traffic jam caused by tau proteins.

In neurons, several intracellular cargoes are transported by motor proteins (kinesins) which walk on microtubules (MTs). However, kinesins can possibly unbind from the MTs before they reach their destinations. The unbound kinesins randomly diffuse in neurons until they bind to MTs. Then, they walk again along the MTs to continue their tasks. Kinesins repeat this cycle of motion until they transport their cargoes to the destinations. However, most previous models mainly focused on the motion of kinesins when they walk on MTs. Thus, a new model is required to encompass the various types of kinesin motion. We developed a comprehensive model and studied the long-range axonal transport of neurons using the model. To enhance reliability of the model, it was constructed based on multiphysics on kinesin motion (i.e., chemical kinetics, diffusion, fluid dynamics, nonlinear dynamics, and stochastic characteristics). Also, parameter values for kinesin motions are carefully obtained by comparing the model predictions and several experimental observations. The axonal transport can be degraded when a large number of binding sites on MTs are blocked by excessive tau proteins. By considering the interference between walking kinesins and tau molecules on MTs, effects of tau proteins on the axonal transport are studied. One of the meaningful predictions obtained from the model is that the velocity is not an effective metric to estimate the degradation of the transport because the decrease in velocity is not noticeable when the concentration of tau protein is not high. However, our model shows that the transport locally changes near tau molecules on MTs even when the change in the velocity is not significant. Thus, a statistical method is proposed to detect this local change effectively. The advantage of this method is that a value obtained from this method is highly sensitive to the concentration of tau protein. Another benefit of this method is that this highly sensitive value can be acquired with relatively low precision and low temporal resolution considering the time scale and length scale of the kinesin motion. This method can be used to estimate the condition of the axonal transport system.

Fusion of Mobile In situ and Satellite Remote Sensing Observations of Chemical Release Emissions to Improve Disaster Response

Chemical release disasters have serious consequences, disrupting ecosystems, society, and causing significant loss of life. Mitigating the destructive impacts relies on identification and mapping, monitoring, and trajectory forecasting. Improvements in sensor capabilities are enabling airborne and spacebased remote sensing to support response activities. Key applications are improving transport models in complex terrain and improved disaster response. Chemical release disasters have serious consequences, disrupting ecosystems, society, and causing significant loss of life. Mitigating the destructive impacts relies on identification and mapping, monitoring, and trajectory forecasting. Improvements in sensor capabilities are enabling airborne and space-based remote sensing to support response activities. Key applications are improving transport models in complex terrain and improved disaster response. Understanding urban atmospheric transport in the Los Angeles Basin, where topographic influences on transport patterns are significant, was improved by leveraging the Aliso Canyon leak as an atmospheric tracer. Plume characterization data was collected by the AutoMObile trace Gas (AMOG) Surveyor, a commuter car modified for science. Mobile surface in situ CH4 and winds were measured by AMOG Surveyor under Santa Ana conditions to estimate an emission rate of 365±30% Gg yr-1. Vertical profiles were collected by AMOG Surveyor by leveraging local topography for vertical profiling to identify the planetary boundary layer at ~700 m. Topography significantly constrained plume dispersion by up to a factor of two. The observed plume trajectory was used to validate satellite aerosol optical depth-inferred atmospheric transport, which suggested the plume first was driven offshore, but then veered back towards land. Numerical long-range transport model predictions confirm this interpretation. This study demonstrated a novel application of satellite aerosol remote sensing for disaster response.

Comparison of the regional CO<sub>2</sub> mole fraction filtering approaches at a WMO/GAW regional station in China

Abstract. The identification of atmospheric CO2 observation data which are minimally influenced by very local emissions/removals is essential for trend analysis, for the estimation of regional sources and sinks, and for the modeling of long-range transport of CO2. In this study, four approaches are used to filter the atmospheric CO2 observation records from 2009 to 2011 at one World Meteorological Organization/Global Atmosphere Watch (WMO/GAW) regional station (Lin'an, LAN) in China. The methods are based on the concentration of atmospheric black carbon (BC), on a statistical approach (robust extraction of baseline signal, REBS), on CH4 as an auxiliary tracer (AUX), and on meteorological parameters (MET). All approaches do suitably well to capture the seasonal CO2 cycle at LAN. Differences are observed in the average regional mole fractions with annual values in the REBS method at least 1.7 ± 0.2 ppm higher than the other methods. The BC method may underestimate the regional CO2 mole fractions during the winter–spring period and should be treated with caution. The REBS method is a purely statistical method and it may also introduce errors on the regional CO2 mole fraction evaluations, as the filtered trend may be influenced by the "noisy" raw data series. Although there are correlations between CH4 and CO2 mole fractions at LAN, the different source/sink regimes may introduce bias on the regional CO2 estimation in the AUX method, typically in summer. Overall, the MET method seems to be the most favorable because it mainly focuses on the influence of potential local sources and sinks, and considers diurnal variations and meteorological conditions. Using the MET method, the annual growth rate of regional CO2 at LAN is determined to be 3.1 ± 0.01 ppm yr−1 (standard error) from 2009 to 2011.