Found 10001 publications. Showing page 361 of 401:
Acoustic waves below the frequency limit of human hearing - infrasound - can travel for thousands of kilometres in the atmosphere. The global propagation signature of infrasound is highly sensitive to the wind structure of the stratosphere.
This work exploits processed continuous data from three high-latitude infrasound stations to characterize an aspect of the stratospheric polar vortex. Concretely, a mapping is developed which takes the infrasound data from these three stations as input and outputs an estimate of the polar cap zonal mean wind averaged over 60-90 degrees in latitude at the 1 hPa pressure level. This stratospheric diagnostic information is relevant to, for example, sudden stratospheric warming assessment and sub-seasonal prediction.
The considered acoustic data is within a low-frequency regime globally dominated by so-called microbarom infrasound, which is continuously radiated into the atmosphere due to nonlinear interaction between counter-propagating ocean surface waves.
We trained a stochastics-based machine learning model (delay-SDE-net) to map between a time series of five years (2014-2018) of processed infrasound data and the ERA5 (reanalysis-based) daily average polar cap wind at 1 hPa for the same period. The ERA5 data was hence treated as ground-truth. In the prediction, the delay-SDE-net utilizes time-lagged inputs and their dependencies, as well as the day of the year to account for seasonal differences. In the validation phase, the input was the 2019 and 2020 infrasound time series, and the model inference results in an estimate of the daily average polar cap wind time-series. This result was then compared to the ERA5 representation of the stratospheric diagnostic time-series for the same period.
The applied machine learning model is based on stochastics and allows for an interpretable approach to estimate the aleatoric and epistemic prediction uncertainties. It is found that the mapping, which is only informed of the trained model, the day of year, and the infrasound data from three stations, generates a 1 hPa polar cap average wind estimate with a prediction error standard deviation of around 10 m/s compared to ERA5.
Focus should be put on the winter months because this is when the coupling between the stratosphere and the troposphere can mostly influence the surface conditions and provide additional prediction skill, in particular during strong and weak stratospheric polar vortex regimes. The infrasound data is available in real-time, and we discuss how the developed approach can be extended to provide near real-time stratospheric polar vortex diagnostics.
2023
Traveling planetary waves surrounding sudden stratospheric warming events can result from direct propagation from below or in situ generation. They can have significant impacts on the circulation in the mesosphere and lower thermosphere. Our study runs a series of ensembles initialized from the Whole Atmosphere Community Climate Model, Version 4, nudged up to 50 km by six-hourly Modern-Era Retrospective Analysis for Research and Application, Version 2, reanalysis to compile a library of sudden stratospheric warming events. To our knowledge, we present the first composite or ensemble study that attempts to link direct propagation and in situ generation by evaluating the wave geometries associated with the overreflection perspective, a framework used to describe how planetary waves interact with critical and turning levels. The present study looks at the evolution of these interactions through the onset of sudden stratospheric warmings with an elevated stratopause or ES-SSWs. Robust and unique features of ES-SSWs are determined by employing an ensemble study that compares ES-SSWs with normal winters. Our study evaluates the production and impacts of westward-propagating, quasi-stationary, and eastward-propagating planetary waves surrounding ES-SSWs. Our results show that eastward-propagating planetary waves are generated within the westward stratospheric wind layer after ES-SSW onset which aids in restoring the eastward stratospheric wind. The interaction of quasi-stationary and westward-propagating waves with the westward stratospheric wind is explored from an overreflection perspective and reaffirms that westward-propagating planetary waves are produced from instabilities at the top of the westward stratospheric wind reversal.
2023
Review of Interpreting Gaseous Pollution Data Regarding Heritage Objects
Pollutant gases pose a significant risk to some cultural heritage objects, and surveys have shown that the professionals involved consider themselves to lack knowledge to fully assess risk. Three approaches towards risk assessment, research results, standards and damage functions have been considered. An assessment tool has been developed, collating over 4000 research reports into a scheme for the impact on 22 materials of acetic and formic acids, nitrogen dioxide, ozone and reduced sulphur gases. The application of doses or concentrations has been considered, the impact of measurement time compared to annual exposure investigated and a simple tool derived.
2023
2023
2023
2023
Quality-assured aerosol optical properties (AOP) with high spatiotemporal resolution are vital for the accurate estimation of direct aerosol radiative forcing and solar irradiance under clear skies. In this study, the sky information from an all-sky imager (ASI) is used with machine learning (ML) synergy to estimate aerosol optical depth (AOD) and the Ångström Exponent (AE). The retrieved AODs (AE) revealed good accuracy, with a dispersion error lower than 0.07 (0.15). The retrieved ML AOPs are used to estimate the DNI by applying radiative transfer modeling. The estimated ML DNI calculations revealed adequate accuracy to reproduce reference measurements with relatively low uncertainties.
2023
Black carbon emitted by incomplete combustion of fossil fuels and biomass has a net warming effect in the atmosphere and reduces the albedo when deposited on ice and snow; accurate knowledge of past emissions is essential to quantify and model associated global climate forcing. Although bottom-up inventories provide historical Black Carbon emission estimates that are widely used in Earth System Models, they are poorly constrained by observations prior to the late 20th century. Here we use an objective inversion technique based on detailed atmospheric transport and deposition modeling to reconstruct 1850 to 2000 emissions from thirteen Northern Hemisphere ice-core records. We find substantial discrepancies between reconstructed Black Carbon emissions and existing bottom-up inventories which do not fully capture the complex spatial-temporal emission patterns. Our findings imply changes to existing historical Black Carbon radiative forcing estimates are necessary, with potential implications for observation-constrained climate sensitivity.
2023
This report presents European interim air quality maps for 2021, which are based on the non-validated up-to-date (UTD) measurement data and the CAMS Ensemble Forecast modelling results, together with other supplementary data. It contains maps of PM10 and NO2 annual averages and ozone indicator SOMO35.
ETC/HE
2023
2023
Review of methods that can be used in the assessment of atmospheric deposition
There are three main approaches for estimating the atmospheric deposition: 1) From measurements of air and precipitation chemistry combined with statistical interpolation, 2) Chemical transport models, 3) Combined observations and atmospheric model calculations. This report reviews these different approaches and come with some general recommendations on the different strategies and the way forward for Poland.
The report was made for the project "Strengthening of atmospheric deposition assessment in Poland based on Norwegian experience" under the program "Environment, Energy and Climate Change", financed by the European Economic Area Financial Mechanism 2014-2021".
NILU
2023
2023
2023
Increased contribution of biomass burning to haze events in Shanghai since China’s clean air actions
High levels of East Asian black carbon (BC) aerosols affect ecological and environmental sustainability and contribute to climate warming. Nevertheless, the BC sources in China, after implementing clean air actions from 2013‒2017, are currently elusive due to a lack of observational constraints. Here we combine dual-isotope-constrained observations and chemical-transport modelling to quantify BC’s sources and geographical origins in Shanghai. Modelled BC concentrations capture the overall source trend from continental China and the outflow to the Pacific. Fossil sources dominate (~70%) BC in relatively clean summer. However, a striking increase in biomass burning (15‒30% higher in a fraction of biomass burning compared to summer and 2013/2014 winter), primarily attributable to residential emissions, largely contributes to wintertime BC (~45%) pollution. It highlights the increasing importance of residential biomass burning in the recent winter haze associated with >65% emissions from China’s central-east corridor. Our results suggest clearing the haze problem in China’s megacities and mitigating climate impact requires substantial reductions in regional residential emissions, besides reducing urban traffic and industry emissions.
2023
Fine-resolution spatio-temporal maps of near-surface urban air temperature (Ta) provide crucial data inputs for sustainable urban decision-making, personal heat exposure, and climate-relevant epidemiological studies. The recent availability of IoT weather station data allows for high-resolution urban Ta mapping using approaches such as interpolation techniques or machine learning (ML). This study is aimed at executing these approaches and traditional numerical modeling within a practical and operational framework and evaluate their practicality and efficiency in cases where data availability, computational constraints, or specialized expertise pose challenges. We employ Netatmo crowd-sourced weather station data and three geospatial mapping approaches: (1) Ordinary Kriging, (2) statistical ML model (using predictors primarily derived from Earth Observation Data), and (3) weather research and forecasting model (WRF) to predict/map daily Ta at nearly 1-km spatial resolution in Warsaw (Poland) for June–September and compare the predictions against observations from 5 meteorological reference stations. The results reveal that ML can serve as a viable alternative approach to traditional kriging and numerical simulation, characterized by reduced complexity and higher computational speeds within the domain of urban meteorological studies (overall RMSE = 1.06 °C and R2 = 0.94, compared to ground-based meteorological stations). The results have implications for identifying the urban regions vulnerable to overheating and evidence-based urban management in response to climate change. Due to the open-sourced nature of the applied predictors and input parsimony, the ML method can be easily replicated for other EU cities.
2023
2023
The choice of the minimum ventilation rate (Vmin) in a demand-controlled ventilation strategy can influence energy demand but also introduce outdoor air pollutants. The latter may have direct health effects, as well as affect indoor chemical reactions. In this paper, we evaluate the effect of ventilation rates and operation hours on the level of CO2, nitrogen dioxide (NO2), and ozone (O3) in a classroom during normal use. We compared the baseline ventilation scenario (S0) with a Vmin of 430 m3/h with S1; Vmin of 150 m3/h for normal ventilation operation time (6:30-17:00) and continuous ventilation for 24h (S2). We found that S1 with reduced Vmin would lower the ozone concentration by 35% during the hours before occupancy compared to S0. Moreover, continuous ventilation during night time with a low Vmin resulted in almost as high O3 concentrations as the baseline ventilation scenario. As O3 reacts easily with certain VOCs to produce secondary organic aerosols, the level of Vmin and the ventilation duration would impact the indoor air quality upon entering the classroom.
2023
Information on the global production and environmental releases of persistent organic pollutants (POPs) is of critical importance for regulating and eliminating these chemical substances of worldwide environmental and health concerns. Here, we conduct an extensive literature review to collect and curate quantitative information on the historical global production and multimedia environmental releases of 25 intentionally produced POPs. Our assembled data indicate that as of 2020, a cumulative total of 31 306 kilotonnes (kt) of the 25 POPs had been synthesized and commercialized worldwide, resulting in cumulative releases of 20 348 kt into the global environment. As of 2020, short-chain chlorinated paraffins were the most produced POP, with a historical global cumulative tonnage amounting to 8795 kt, whereas α-hexachlorocyclohexane (HCH) had the largest historical global cumulative environmental releases of 6567 kt among these 25 POPs. The 1970s witnessed the peak in the annual global production of the 25 investigated POPs. The United States and Europe used to be the hotspots of environmental releases of the 25 investigated POPs, notably in the 1960s and 1970s. By contrast, global environmental releases occurred primarily in China in the 2000s–2010s. Preliminary efforts are also made to integrate the production volume information with “hazard” attributes (persistence, bioaccumulation, toxicity, and long-range transport potential) in the evaluation of potential environmental impacts of the 25 POPs. The results show that dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCBs) are potentially associated with higher environmental impacts than other POPs because they are among the top rankings in both the global cumulative production and hazard indicators. This work for the first time reveals the astonishing magnitudes of POP production and environmental releases in contemporary human history. It also underscores the importance of tonnage information in assessments of POPs, POP candidates, and other chemicals of emerging concern.
2023
Environmental pollutants in the terrestrial and urban environment 2021. Revised report.
Samples from the urban terrestrial environment in the Oslo area were analysed for metals and a large number of organic environmental pollutants. The selected samples that were analysed were soil, earthworm, fieldfare egg and liver, brown rat liver, roe deer liver, vegetation, insects and red fox liver. Biomagnification-potential was estimated based on detected data for relevant predator-prey pairs.
NILU
2023