Hasil untuk "Meteorology. Climatology"

Taraneh Mihankhah, Yushan Su, Tianchu Zhang et al.

This study characterizes cancer and non-cancer risks due to inhalation exposure to volatile organic compounds (VOCs) in a border city of Windsor in southern Ontario, Canada, using hourly ambient concentrations collected from 17 November 2021 to 17 March 2023. The total incremental lifetime cancer risk (CR) due to benzene and ethylbenzene is 4.33 × 10⁻⁶, which is in the acceptable risk range of 1 × 10⁻⁶ to 1 × 10⁻⁴ used by the USEPA. The CR was higher in winter (5.20 × 10⁻⁶), followed by fall (4.32 × 10⁻⁶), spring (3.86 × 10⁻⁶), and summer (2.96 × 10⁻⁶), all in the acceptable range. The total chronic non-cancer risk (Hazard Quotient, HQ) of inhalation exposure to 16 VOCs was 0.0488, with a higher value in fall (0.0571), followed by winter (0.0464), and lower in spring (0.0454) and summer (0.0451), all in the safe level of below HQ = 1 used by the USEPA. The hazard index (HI) by organs was higher for the nervous system (0.0213), followed by the hematologic system and immune system (0.0165 each), but much lower for the other five target organs, i.e., the liver/kidney (1.52 × 10⁻⁴), developmental system (3.38 × 10⁻⁴), endocrine system and urinary system (2.82 × 10⁻⁴ each), and respiratory system (9.70 × 10⁻⁵). Similar hour-of-day trends were observed in the total CR, total HQ, and HI by organs with higher values in the early morning hours of 5:00–8:00 and lower values during 12:00 to 15:00. Benzene was the major contributor to both total CR (89%) and total HQ (34%) due to its high toxicity and high concentrations. Benzene, toluene, ethylbenzene, and xylenes (BTEX) contributed 100% of the total CR and 51% of the total HQ. Further, BTEX is the sole contributor to the HI for the hematologic system and immune system and the major contributor to the HI for the nervous system (39%) and developmental system (55%). Higher cancer and non-cancer risks were associated with the airmass from the east, southeast, and southwest of Windsor.

N. Badullovich, D. Tucker, R. Amoako et al.

Abstract Increasingly, climate activists use nonviolent civil disobedience (NVCD) to raise awareness about the need to end fossil fuel use. In two small studies we explored the potential of NVCD to enhance U.S. public support for this goal. Study 1 showed that some NVCD actions (e.g., marches and sit-ins) and some targets of those actions (e.g., fossil fuel companies) are seen as more acceptable than other targets (e.g., ordinary people). Study 2 suggested that perceived acceptable NVCD actions against perceived acceptable targets may be more effective than other forms of NVCD. We provide some potential directions for future research to better elucidate understanding on this topic.

Yanxia JI, Xin SUN, Hanbin ZHANG et al.

Convection-allowing ensemble prediction (CAEP) is an important approach to improve the capability of strong convective weather prediction, and how to construct reasonable initial disturbance is one of the key issues of CAEP. In this paper, the experiments of the per⁃ turbed-observation (PO) method in the CAEP system in the Inner Mongolia region were carried out and evaluated by comparing them with the downscaling (DOWN) method. The performance of the PO method in the CAEP system was then analyzed, which will provide a technical ref⁃ erence for the construction of the CAEP system in Inner Mongolia. The results are as follows. (1) The initial perturbation constructed by the PO method can effectively include the observations in the Inner Mongolia region, which can reduce the uncertainty of the background field and the perturbation has sufficient growth capacity. (2) Compared with the DOWN method, the PO method can significantly reduce the short-term forecast error of CAEP. The root mean square error (RMSE) of upper-level elements is reduced by 4% ~43%, and the RMSE of ground surface elements is reduced by 3% ~9%, suggesting a slightly decreased ensemble spread. The continuous ranked probability score (CRPS) of upper-level elements can be reduced by up to 53% and the CRPS of ground surface elements is reduced by an average of 6%, which generally indicates an improvement in the quality of convective scale ensemble forecasts. (3) The PO method can also improve the capability of short-term precipitation forecasts. The TS score for precipitation levels of 0.1 mm, 4 mm, and 13 mm increased by 0.015, 0.003, and 0.0015, re⁃ spectively. Furthermore, the case study shows that the PO method is more accurate in predicting the precipitation areas and intensity levels.

Tianchu Zhang, Yushan Su, Jerzy Debosz et al.

This study investigated the sensitivity of the positive matrix factorization (PMF) model using concentrations of PM_2.5-bound elements in Windsor, Ontario, Canada. Five scenarios were devised to assess impacts of input data on source identification, source contributions, and model performance. The study found that the model outcomes and performance were not sensitive to data below method detection limits (MDLs) being replaced with ½ MDLs, nor whether brown carbons (BrCs) data were excluded. By analyzing two episodic events individually, unique factors of fireworks and mineral dust were identified for each of the two episodes. Moreover, PMF model performance was improved greatly for event markers of the episodes and elements with less variability in concentration when compared with the base case scenario. Excluding the two episodes from the entire dataset had little impact on factor identification and source contributions but improved the model performance for three out of twelve elements unique to the two episodes. Overall, the PMF model outcomes and performance were sensitive to percentages of concentrations below MDLs and element concentrations with large variability due to high concentrations observed in episodes. Our findings are useful for dealing with data below MDLs and episodic events in conducting future PMF source apportionment of PM_2.5-bound elements.

Michał Ciepły, Dariusz Ignatiuk, Mateusz Moskalik et al.

We describe the annual pattern of frontal ablation driven by submarine melting mechanisms at the Hansbreen terminus: these are reflected in the intensity and spatial distribution of calving events. Analysis of time-lapse images of the Hansbreen front in conjunction with oceanographic and meteorological data shows that calving intensity is driven primarily by seawater temperature. Regression analysis also highlights the importance of air temperature, which we take to be a proxy for surface ablation and subglacial discharge. This, combined with seasonal changes in ice cliff tortuosity and the increasing significance of wave motion outside the ablation season, enabled us to determine seasonal changes in the mechanisms of ice cliff undercutting by submarine melting. While submarine melting controlled by estuarine circulation primarily drives frontal ablation in summer, wave-driven melting at the waterline is more important outside the ablation season. During winter, ice cliff undercutting by melting is suspended by low seawater temperature, negligible subglacial water discharge and sea-ice cover. The most intense frontal ablation, recorded in summer, was related to higher sea temperature and vigorous estuarine circulation.

F. J. Pérez-Invernón, H. Huntrieser, S. Soler et al.

Abstract. Lightning is the major cause of natural ignition of wildfires worldwide and produces the largest wildfires in some regions. Lightning strokes produce about 5 % of forest fires in the Mediterranean basin and are one of the most important precursors of the largest forest fires during the summer. Lightning-ignited wildfires produce significant emissions of aerosols, black carbon and trace gases, such as CO, SO2, CH4 and O3, affecting air quality. Characterization of the meteorological and cloud conditions of lightning-ignited wildfires in the Mediterranean basin can serve to improve fire forecasting models and to upgrade the implementation of fire emissions in atmospheric models. This study investigates the meteorological and cloud conditions of Lightning-Ignited Wildfires (LIW) and Long-Continuing-Current (LCC) lightning flashes in the Iberian Peninsula and Greece. LCC lightning and lightning in dry thunderstorms with low precipitation rate have been proposed to be the main precursors of the largest wildfires. We use lightning data provided by the World Wide Lightning Location Network (WWLLN), the Earth Network Total Lightning Network (ENTLN) and the Lightning Imaging Sensor (LIS) onboard the International Space Station (ISS) together with four databases of wildfires produced in Spain, Portugal, Southern France and Greece, respectively, in order to produce a climatology of LIW and LCC lightning over the Mediterranean basin. In addition, we use meteorological data provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5-reanalysis data set and by the Spanish State Meteorological Agency (AEMET) together with the Cloud Top Height (CTH) product derived from Meteosat Second Generation (MSG) satellites measurements to investigate the meteorological conditions of LIW and LCC lightning. According to our results, LIW and a significant amount of LCC lightning flashes tend to occur in dry thunderstorms with weak updrafts. Our results suggest that lightning-ignited wildfires tend to occur in high-based clouds with a vertical content of moisture lower than the climatological value, as well as with a higher temperature and a lower precipitation rate. Meteorological conditions of LIW from the Iberian Peninsula and Greece are in agreement, although some differences possibly caused by highly variable topography in Greece and a more humid environment are observed. These results show the possibility of using the typical meteorological and cloud conditions of LCC lightning flashes as proxy to parameterize the ignition of wildfires in atmospheric or forecasting models.

Diana-Alexandra GIURGIU

Heatwaves are recognized, although there is still no general acknowledged definition, as periods of unusually hot and dry or hot and humid weather, which occur gradually and cease in the same way, lasting at least 2 to 3 days with visible impact on human activities. Episodes characterized by heatwaves induce excessively hot weather compared to the local climatic specific features. The period with or without heatwaves is different from a region to another, depending on the particularities of each area. This climatological hazard can be described as an advection of tropical air mass which, compared to the climatological standards, leads to reaching large positive temperature deviations, that in some cases will set new thermal records. In the northern hemisphere, in the area of temperate latitudes, which includes Romania, the highest values of air temperature are generally recorded from mid-June to the end of August. Heatwaves in Romania are mainly generated by the advection of continental hot air masses from North Africa, leading to a stable stratification of the atmosphere from ground levels to more higher ones. The ridge of the North African anticyclone extends either over Central Europe or Central Eastern Europe, up to Romania, generating heatwaves for the first scenario in the western regions of our country, whereas or the second one outside the Carpathians, most frequently in the Romanian Plain. In Romania, the most frequent heatwaves, taken by duration in time are those between 2 and 5 days. while analysed in terms of intensity, stand out those during summer months (June to August).

L. Kalkstein, Guanri Tan, J. Skindlov

Lixing Shen, Chuanfeng Zhao, Xingchuan Yang

Sea‐land breeze (SLB) is a critical component of the urban environment, wind power utilization, fishing industry, etc. along coastal areas where 40% world population live. Surrounding meteorological factors like the background wind field, temperature, and cloud fraction have all been reported to greatly impact SLB evolution. However, a climatological understanding of SLBs over the globe remains limited. This study quantifies the significance of SLBs under different climates over the globe for the first time, and investigates the long‐term trends in SLBs where there is significant existence of SLB. The results demonstrate that climate type plays a leading role in the significance and trends of global SLBs while special surface conditions, ocean currents, and landscapes explain abnormal cases. Climatologically, adequate in‐situ solar radiation and mild background meteorological field are the two root factors that ensure the significant existence of SLB.

D. Kinnison, G. Brasseur, S. Walters et al.

T.-S. Neset, J. Wilk, S. Cruz et al.

Interactive mobile technologies provide an emerging opportunity for citizens to engage with and enhance urban climate resilience, both as providers of locally situated data on climate variables, impacts and climate adaptation measures as well as to obtain information on local conditions and recommendations.This paper examines the process of co-designing a citizen science application for urban climate resilience in four European cities. Further, the paper studies if and how the system enables knowledge co-production to increase urban resilience following process principles for co-production of climate services and discusses the legitimacy, transparency, credibility, and relevance of the process. We further assess the role that a citizen science climate service could play as a boundary object in knowledge co-production. We draw on experiences from a co-design process that included municipal stakeholders from different sectors as well as municipal employees and civil society end-users involved in campaigns. This study identified a set of barriers and enablers for the co-design process and concludes that the CitizenSensing application can fulfil the role of a boundary object, but that the co-design process is a balancing act between navigating time constraints, including stakeholders’ different and changing demands and perspectives while retaining a high level of flexibility and reflexivity.

A. Arguez, R. Vose

Emelie Linnéa Graham, Paul Zieger, Claudia Mohr et al.

The size distribution, volatility and hygroscopicity of ambient aerosols and cloud residuals were measured with a differential mobility particle sizer (DMPS) and a volatility–hygroscopicity tandem differential mobility analyser (VHTDMA) coupled to a counterflow virtual impactor (CVI) inlet during the Cloud and Aerosol Experiment at Åre (CAEsAR) campaign at Mt. Åreskutan during summer 2014. The chemical composition of particulate matter (PM) and cloud water were analysed offline using thermo-optical OC/EC analysis and ion chromatography. The importance of aerosol particle size for cloud droplet activation and subsequent particle scavenging was clearly visible in the measured size distributions. Cloud residuals were shifted towards larger sizes compared to ambient aerosol, and the cloud events were followed by a size distribution dominated by smaller particles. Organics dominated both PM (62% organic mass fraction) and cloud water (63% organic mass fraction) composition. The volatility and hygroscopicity of the ambient aerosols were representative of homogeneous aged aerosol with contributions from biogenic secondary organics, with median volume fraction remaining (VFR) of 0.04–0.05, and median hygroscopicity parameter κ of 0.16–0.24 for 100–300 nm particles. The corresponding VFR and κ for the cloud residuals were 0.03–0.04 and 0.18–0.20. The chemical composition, hygroscopicity and volatility measurements thus showed no major differences between the ambient aerosol particles and cloud residuals. The VFR and κ values predicted based on the chemical composition measurements agreed well with the VHTDMA measurements, indicating the bulk chemical composition to be a reasonable approximation throughout the size distribution. There were indications, however, of some more subtle changes in time scales not achievable by the offline chemical analysis applied here. Further, online observations of aerosol and cloud residual chemical composition are therefore warranted.

Dro Touré Tiemoko, Fidèle Yoroba, Jean-Daniel Paris et al.

The contribution in terms of long-range transport of CO₂, CH₄, and CO concentrations to measurements at Lamto (5°02′ W–6°13′ N) was analyzed for the 2014–2017 period using the FLEXPART model that calculates the retro-plumes of air masses arriving at the station. The identification of the source-receptor relationships was also studied with a clustering technique applied on those retro-plumes. This clustering technique enabled us to distinguish four categories of air mass transports arriving at Lamto site described as follows: oceanic and maritime origin (≈37% of the retro-plumes), continental origin (≈21%), and two hybrid clusters (≈42%). The results show that continental emission sources contribute significantly to the increases in concentrations of CO₂, CH₄, and CO and explain ≈40% of their variance. These emission sources are predominantly from north and north-east directions of the measurement point, and where densely populated and economically developed areas are located. In addition, the transport of air masses from these directions lead to the accumulation of CO₂, CH₄, and CO. Furthermore, the ratios ΔCO/ΔCH₄ and ΔCO/ΔCO₂ observed in the groups associated with Harmattan flows clearly show an influence of combustion processes on the continent. Thus, the grouping based on FLEXPART footprints shows an advantage compared to the use of simple trajectories for analyzing source–receptor relationships.

Jung-Hyun Kim, Jiyeon Park, Sol-Bin Kim et al.

A geographical source of <i>n</i>-alkanes in marine aerosols was assessed along a North–South transect in the Arctic–Northwest Pacific region. Marine aerosol samples were collected during the ARA08 cruise with the R/V Araon between 28 August and 28 September 2017. We investigated molecular distributions of <i>n</i>-alkanes (homologous series of C₁₆ to C₃₄) and compound-specific stable carbon isotopes (δ¹³C) of <i>n</i>-C₂₇, <i>n</i>-C₂₉, and <i>n</i>-C₃₁. Unresolved complex mixtures (UCM) showed a latitudinal trend from the Arctic Ocean to the northwest Pacific Ocean, highlighting an increasing influence of the plume of polluted air exported from East Asian countries. The anthropogenic input was further evidenced by high U/R ratios (>5) and low CPI_17–23 (0.6–1.4). The occurrence of high molecular weight (HMW) <i>n</i>-alkanes with high CPI_27–31 (>3) indicated the biogenic input of terrestrial higher plant leaf waxes in all studied samples. The δ¹³C of HMW <i>n</i>-alkanes was influenced by both the relative contributions from the C₃/C₄ plant sources and from fossil fuel combustions. The back-trajectory analyses provided evidence that changes in molecular distributions and δ¹³C of <i>n</i>-alkanes were due to the long-range atmospheric transport of anthropogenic and biogenic organic materials from North American and East Asian countries to the Arctic Ocean and the remote northwest Pacific Ocean, respectively.

Xian-Chun Tan, Yuan Zeng, Bai-He Gu et al.

Reductions in the transportation sector's carbon dioxide emissions are increasingly of global concern. As one of the first low-carbon pilot and carbon trading pilot cities, and as one of the largest automobile production bases in China, Chongqing has multiple low-carbon transportation policies that are coupled. In this study, three policy scenarios are set, including: 1) improving the fuel economy of newly sold gasoline passenger cars to 5.7 l per 100 km by 2020, 2) promoting pure electric private cars to increase the share to 7% of private car sales by 2020, and 3) the policy mix scenario of the above two policies. Simulations are undertaken with the Chinese Academy of Sciences general equilibrium (CAS-GE) model, a type of computable GE model, to assess the macro-economic impact and the industrial impact of the three policy scenarios. Through the policy impact mechanism analysis and data-mapping process, the micro-economic impact analysis results, including costs and fuel savings, for the two policies from the bottom-up model are taken as the shock variables and inputs for the CAS-GE model. The results show that: 1) the two policies will both have a slightly negative impact (−0.09% and −0.30%) on Chongqing's GDP in 2020; 2) the employment rate will decrease by 0.12% and 0.47%, but the inflation rate will be restrained to a certain extent (−0.21% and −0.17%); and 3) the complementarity of the mixed policy can weaken the negative impact of the two policies when implemented separately. The mixed policy will reduce the GDP slightly by 0.37%, compared with the cumulative effect of the two policies implemented separately, resulting in cost-effective synergies at the macro-economic impact level; and 4) the COVID-19 pandemic in 2020 has an uncertain impact on the results. The method and results can provide a reference for the formulation and adjustment of low-carbon transportation policies in other large cities.

Xianyong Meng, Hao Wang, C. Shi et al.

We describe the construction of a very important forcing dataset of average daily surface climate over East Asia—the China Meteorological Assimilation Driving Datasets for the Soil and Water Assessment Tool model (CMADS). This dataset can either drive the SWAT model or other hydrologic models, such as the Variable Infiltration Capacity model (VIC), the Soil and Water Integrated Model (SWIM), etc. It contains several climatological elements—daily maximum temperature (°C), daily average temperature (°C), daily minimum temperature (°C), daily average relative humidity (%), daily average specific humidity (g/kg), daily average wind speed (m/s), daily 24 h cumulative precipitation (mm), daily mean surface pressure (HPa), daily average solar radiation (MJ/m2), soil temperature (K), and soil moisture (mm3/mm3). In order to suit the various resolutions required for research, four versions of the CMADS datasets were created—from CMADS V1.0 to CMADS V1.3. We have validated the source data of the CMADS datasets using 2421 automatic meteorological stations in China to confirm the accuracy of this dataset. We have also formatted the dataset so as to drive the SWAT model conveniently. This dataset may have applications in hydrological modelling, agriculture, coupled hydrological and meteorological modelling, and meteorological analysis.

P. Tunved, J. Ström, R. Krejci

Abstract. In this study we present a qualitative and quantitative assessment of more than 10 yr of aerosol number size distribution data observed in the Arctic environment (Mt. Zeppelin (78°56' N, 11°53' E, 474 m a.s.l.), Ny Alesund, Svalbard). We provide statistics on both seasonal and diurnal characteristics of the aerosol observations and conclude that the Arctic aerosol number size distribution and related parameters such as integral mass and surface area exhibit a very pronounced seasonal variation. This seasonal variation seems to be controlled by both dominating source as well as meteorological conditions. Three distinctly different periods can be identified during the Arctic year: the haze period characterized by a dominating accumulation mode aerosol (March–May), followed by the sunlit summer period with low abundance of accumulation mode particles but high concentration of small particles which are likely to be recently and locally formed (June–August). The rest of the year is characterized by a comparably low concentration of accumulation mode particles and negligible abundance of ultrafine particles (September–February). A minimum in aerosol mass and number concentration is usually observed during September/October. We further show that the transition between the different regimes is fast, suggesting rapid change in the conditions defining their appearance. A source climatology based on trajectory analysis is provided, and it is shown that there is a strong seasonality of dominating source areas, with Eurasia dominating during the Autumn–Winter period and dominance of North Atlantic air during the summer months. We also show that new-particle formation events are rather common phenomena in the Arctic during summer, and this is the result of photochemical production of nucleating/condensing species in combination with low condensation sink. It is also suggested that wet removal may play a key role in defining the Arctic aerosol year, via the removal of accumulation mode size particles, which in turn have a pivotal role in facilitating the conditions favorable for new-particle formation events. In summary the aerosol Arctic year seems to be at least qualitatively predictable based on the knowledge of seasonality of transport paths and associated source areas, meteorological conditions and removal processes.

J. Adam, D. Lettenmaier

A. Tait, R. Henderson, R. Turner et al.