Favorable Meteorological Conditions Research Articles

A machine learning modelling approach to characterize the background pollution in the Western Macedonia region in northwest Greece

The background PM10 concentration in the Western Macedonia region, a complex terrain area with combined urban and industrial emission sources is investigated in this study. PM10 measurements were collected from a remote agricultural monitoring site situated in the southern part of the region and outside the industrial basin over a 12-year period (2010–2021). The ongoing reduction in lignite production during the last decade resulted in considerable changes in particulate emissions in the area. To take into account the changes in the air quality of the region the whole period was divided into two subperiods of common air pollution characteristics. For each period, Hidden Markov Models clustering was applied to the deseasonalized daily PM10 concentrations and the corresponding diurnal amplitudes to extract groups of similar characteristics (clusters) and define the background pollution. The average background concentration was estimated at 15.9 μg/m3 during the period 2010–2015 followed by a decrease of 3.1 μg/m3 to 12.8 μg/m3 during the second study period (2016–2021). The examination of the long-term changes in the background concentration revealed a statistically significant decreasing annual trend of −0.39 μg/m3 that reflected the air quality improvement of the region during the last decade. Additionally, background concentrations co-existed with favorable meteorological conditions such as higher wind speeds during the cold period (October–March) diminishing the contribution of local anthropogenic emissions (biomass burning for heating purposes) and a less developed mixing layer during the warm period (April–September) impeding the impact of the particulate plumes from the nearby power plants.

Selection assessment of varieties and selected forms of black currant based on large fruit size

The article presents research findings on the weight of black currant berries. The research focused on the varieties and selected forms of black currant (Ribes nigrum L). Nara variety, adapted to local conditions, was used as a control. Studies were carried out in 2020–2022 at the plots for genetic collection and competitive trials of selected forms of black currants at the All-Russian Research Institute of Lupin (Bryansk region). The planting scheme involved a spacing of 3×0.8 m on grey forest soils. The observations were carried out using conventional methods. The varying weather conditions during the study period allowed for a more objective evaluation of the genotypes in terms of their adaptive capabilities and facilitated the selection of large-fruited and resistant forms. The most favourable meteorological conditions for berry weight development were observed in 2022. During this period, the average berry weight of the studied gene pool was 2.5 g. Among the examined varieties, Dobrynya (3.5 g), Debryansk (2.7 g), Chara (2.6 g) and Selechenskaya 2 (2.6 g) demonstrated the largest berry sizes with variation coefficients of 20%, 28%, 7%, and 17%, respectively. Large-fruited forms having an average berry weight exceeding 3 g and high stability (V=3%) were selected from the hybrid family 6-12- 224×6-26-207 – 7-3-227 (3.6 g), 7-3-213 (3.4 g), 7-19-100 (3.6 g) and Selechenskaya 2×Treasure – 6-20-67 (3.5 g). These genotypes represent valuable parent material for further breeding aimed at increasing berry weight. New large-fruited sources with a combination of important breeding traits (large fruit, high vitamin C content, resistance to powdery mildew and bud mite), namely,7-19-100, 7-3-227, 7-18-250, 7-13-232 and 7-17-150, were identified. The variety Dessert Olkhina exhibited the smallest berries (0.8 g) with a variability of 20%. The influence of weather conditions on the weight of berries was established, revealing a positive average correlation between berry weight and precipitation levels from May to July (r=0.52) and the hydrothermal index of the growing season (r=0.56).

Characteristics and mechanism of a persistent ozone pollution event in Pearl River Delta induced by typhoon and subtropical high

Ozone (O3) is a significant air pollutant in the Pearl River Delta (PRD) region, with severe pollution events primarily associated with the Western Pacific Subtropical High (WPSH) and typhoon periphery synoptic weather patterns. To investigate the continuity and differences in O3 pollution processes influenced by these patterns, we analyze a severe O3 pollution event in Zhuhai from September 10 to 13, 2022. The study collects vertical profiles of O3 from the differential absorption O3 lidar and wind fields observed by the Doppler wind profile lidar. We utilize ground-level monitoring data from national ambient air quality monitoring network and meteorological stations to analyze diurnal variations of air pollutant concentrations and ground-level meteorological conditions. The study reveals that both the WPSH and the typhoon periphery create favorable meteorological conditions for severe O3 pollution events. The highest temperatures during the WPSH and typhoon periphery stages are 32.1 °C and 37.5 °C, respectively. During the WPSH control stage, the combined effects of the inversion layer and light static wind hinder O3 dispersion. The ground-level O3 concentration reaches a maximum of 106 ppb. Then the typhoon periphery control stage, the ground-level O3 peak increases to 170 ppb, showing a 60% increase compared to the WPSH stage. O3 horizontal and vertical transport processes play a crucial role in the O3 episode during this stage. The northerly winds predominantly transport pollutants from upstream urban clusters to the local area, and intense downdrafts facilitate the downward transport of O3 from the residual layer. The study investigates the mechanisms of three-dimensional O3 transport within the boundary layer influenced by the WPSH and typhoon periphery in the PRD region. The results contribute valuable insights to pollution events in the PRD region under typical synoptic weather patterns.

ҚАЗАҚСТАННЫҢ ШЫҒЫСЫНДА АҢЫЗАҚТАРДЫҢ ТАРАЛУ ЕРЕКШЕЛІКТЕРІ

In the research work, the peculiarities of the spread of a meteorological phenomenon dangerous for agriculture – the dry wind in the territory of Eastern Kazakhstan are considered. To achieve this goal, on the basis of long-term data, favorable conditions for the dry wind and the number of days that have passed with the dry season were calculated. In addition, the features of the distribution of the main climatic indicators in the East Kazakhstan region were described. According to the results of the study, during the year favorable meteorological conditions for dry wind are formed in the period from April to November, and the phenomenon of dry wind occurs in May-September. According to the results of calculations, on average, during the warm period of the year in the east of Kazakhstan, the number of favorable conditions for dry wind reaches 60 days, and the number of cases with dry wind reaches 30 days. And in mountainous areas, where there is no shortage of humidity, dry wind is not observed (MS Markakolsky Reserve, Leninogorsk). The areas where the dry wind phenomenon is most often observed correspond to flat and low-mountainous areas with low relative humidity and high wind speed (MS Akzhar, Ayagoz). The results obtained during the research work can be used by specialists working in the field of agriculture, climate research and forecasting of dangerous agrometeorological phenomena.

Impact of Clean Air Policy on Criteria Air Pollutants and Health Risks Across China During 2013–2021

AbstractThe impact of clean air policy enacted in China since 2013 on air quality and human health remained poorly understood. For the first time, we developed a full‐coverage air quality data set including six criteria air pollutants (PM2.5, PM10, NO2, SO2, CO, and 8‐hr O3) using a three‐stage model. Then, the LightGBM model was applied to further quantify the respective contributions of emission and meteorology to air quality. The results suggested that the deweathered concentrations of PM2.5, PM10, NO2, SO2, and CO in China decreased by 46.2%, 43.1%, 24.7%, 55.5%, and 37.2%, respectively. However, the 8‐hr O3 concentration in China increased by 19.4%. The variation trends of deweathered PM2.5 and NO2 were much weaker than the absolute concentrations of these species, indicating more strict emission control measures should be imposed in the future. Based on the comparison of the effectiveness during 2013–2017 and 2018–2021, we found that nearly all of the regions suffered from immense difficulty in reducing PM2.5 emissions in recent years. However, the CO emission control has become more efficient since 2018. The increasing rate of deweathered 8‐hr O3 concentration was more dramatic during 2018–2021 compared with 2013–2017, which was in contrast to the absolute 8‐hr O3 concentration. It suggested that the rapid increase of ambient O3 level might be masked by favorable meteorological conditions since 2018. Although the large reduction of PM2.5 and NO2 saved more health benefits (625,362 cases), the increase of O3 exposure aggravated the health costs (20,419 cases) across China. Therefore, collaborative control of PM2.5, NO2, and O3 pollution are still imperative in the future work.

Qualitative indicators of spring barley varieties (Hordeum vulgare L.) under different growing conditions

Purpose. To evaluate the quality indicators of spring barley seeds grown under different soil and climatic conditions. Methods. Laboratory, calculation and statistical methods were used during the research, analysis and synthesis methods were used to draw conclusions. Results. As a result of research, the dependence of spring barley quality indicators, namely: grain uniformity and protein content, on soil and climatic zones and growing conditions was revealed. Thus, grain uniformity ranged from 86.7% (high, Polissia) to 95.1% (very high, Forest Steppe) in the different test years. In 2021, thanks to favorable meteorological conditions during the growing season, its indicators increased by 4.3% in the Steppe, 4.6% in the Forest Steppe and almost 6.0% in Polissia compared to 2020. On average, the uniformity of grain grown in different bran­ches of UIPVE increased by 5.6%. The maximum values were obtained for the varieties ‘Avus’ – 93.9% (Steppe), ‘Novyi Svitanok’ – 94.5–96.6% (Polissia, Forest Steppe). Depending on the soil and climate zone and the year of the experiment, the protein content in the grain varied from 10.9 (low, Steppe) to 13.4% (medium, Forest Steppe). On ave­rage, this indicator decreased by 2.5% in 2021 compared to 2020, and only in the Polissia zone it increased by 2.6%. The highest protein content was found in the varieties ‘Istr’ – 13.5–13.9% (Steppe and Forest Steppe) and ‘Hercules’ – 13.4% (Polissia). The varieties ‘Amadei’, ‘Istr’ and ‘Novyi Svitanok’ combined both economic and valuable traits. Optimum air temperature and high grain uniformity cont­ribute to increasing the yield of spring barley. At the same time, during the formation of a high yield in the culture, the protein content in the grain decreases. Conclusions. It was revealed that, on average, in 2020–2021, the uniformity of spring barley grain was 92.3% (Steppe), 95.4% (Forest Steppe) and 93.2% (Polissia); the protein content in the grains was 11.8% (Steppe), 12.4% (Forest Steppe) and 11.6% (Polissia). The formation of quality indicators of spring barley seeds was influenced by the growing conditions in the relevant soil and climatic zone.

Combined meteorological, atmospheric stability and spray volume effect on the control of Spodoptera frugiperda (Lepidoptera: Noctuidae) in maize

The fall armyworm, Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae), is the most important maize pest in Brazil and can cause major yield losses. This study aimed determine which the most favorable meteorological and atmospheric stability conditions are for obtaining maximum control effectiveness of S. frugiperda in maize in insecticide applications with different spray volumes. An insect pest natural infestation field experiment was carried in the 2018/2019 season. Spinetoram (12 g a.i. ha-1) was applied three times along the crop cycle. The experimental design was in blocks with nine treatments and four replicates within each block, besides the maintenance of a control treatment without application, totaling 10 treatments. The evaluated factors were the atmospheric condition represented by three times of application (TOA: 8AM, 2 and 6PM) and three spray volumes (SV: 200, 300 and 400 L ha-1). S. frugiperda foliar feeding damage was evaluated using a numerical scale score. Meteorological conditions at the time of application and SV interfered in the pest control effectiveness. Lowest average damage scores were observed in applications carried out at 8 am, when the air and dew point temperatures were lower, and the relative humidity and wind velocity were higher than at 2 pm and 6 pm, and with SV of 400 L ha-1. For the most efficient treatment (8 am - 400 L ha-1) applied at 12/27/2018, the atmosphere was stable.

Comparisons of Spatial and Temporal Variations in PM2.5-Bound Trace Elements in Urban and Rural Areas of South Korea, and Associated Potential Health Risks

PM2.5-bound trace elements were chosen for health risk assessment because they have been linked to an increased risk of respiratory and cardiovascular illness. Since the Korean national air quality standard for ambient particulate matter is based on PM2.5 mass concentration, there have only been a few measurements of PM2.5 particles together with trace elements that can be utilized to evaluate their effects on air quality and human health. Thus, this study describes the trace elements bound to PM2.5 in Seoul (urban area) and Seosan (rural area) using online nondestructive energy-dispersive X-ray fluorescence analysis from December 2020 to January 2021. At both the Seoul and Seosan sites, S, K, Si, Ca, and Fe constituted most of the PM2.5-bound trace elements (~95%); major components such as S, K, and soil (estimatedcalculatedcalculated based on oxides of Si, Fe, Ca, and Ti) were presumably from anthropogenic and crustal sources, as well as favorable meteorological conditions. During winter, synoptic meteorology favored the transport of particles from severely contaminated regions, such as the East Asian outflow and local emissions. The total dry deposition flux for crustal elements was 894.5 ± 320.8 µg m−2 d−1 in Seoul and 1088.8 ± 302.4 µg m−2 d−1 in Seosan. Moreover, potential health risks from the trace elements were estimated. Cancer risk values for carcinogenic trace elements (Cr, As, Ni, and Pb) were within the tolerable limit (1 × 10−6), suggesting that adults and children were not at risk of cancer throughout the study period in Seoul and Seosan. Furthermore, a potential risk assessment of human exposure to remaining carcinogens (Cr, As, Ni, and Pb) and non-carcinogens (Cu, Fe, Zn, V, Mn, and Se) indicated that these trace elements posed no health risks. Nevertheless, trace element monitoring, risk assessment, and mitigation must be strengthened throughout the study area to confirm that trace-element-related health effects remain harmless. Researchers and policymakers can use the database from this study on spatial and temporal variation to establish actions and plans in the future.

On the impact of modern climate change on the increase of grain yields in Russia

In recent years, Russia has seen a steady increase in grain crop yields. A positive trend in meteorological conditions is often considered as the reason for this phenomenon, but there is almost no strong scientific evidence for it. The aim of investigation was to analyze changes in the potential (climatic) grain yields in the country for the period from 2000 to 2022. For this purpose, the simulation model of plant growth WOFOST was used, which allows assessing the impact of all meteorological parameters in a comprehensive manner. The assessment was carried out for a network of representative points (42 points) in different regions of the country for grain crops, taking into account daily meteorological parameters and soil type. Modeling was conducted at the level of potential yield, which takes into account the variation of meteorological parameters only, and it is believed that the limiting influence of other factors on the yield is absent. As a result of the analysis, it was found that the trends of potential yields have different direction in different regions of the country. The trend towards more favorable meteorological conditions for grain crops is observed for the North Caucasus, the lower Volga region, Western Siberia and the Far East, while in the Central and Central Black Earth districts, the upper Volga region, as well as in the south of Central Siberia in recent years there is a drop in the potential yields. The growth of grain yields in recent years agrees well with the trend of changes in agrometeorological conditions in most grain-producing regions of the country. Unidirectional trends in meteorological potential and statistical yields are absent only in the regions of central European Russia, where the role of the climatic factor in grain yield fluctuations is less significant, and where one can assume the effect of measures taken by the government of the country to support and develop agriculture.

Distribution and Meteorological Control of PM2.5 and Its Effect on Visibility in Northern Thailand

In the dry season, the north of Thailand always experiences reduced air quality, reduced visibility, and public health exposure from the burning of biomass domestically and in surrounding countries. The purpose of this research was to investigate the distribution and the meteorological control of PM2.5 accumulation, as well as its effect on visibility in northern Thailand in 2020. The Geographic Information System (GIS) was applied for the analysis of the spatial distribution, while Pearson’s correlation coefficient was utilized to examine the association between PM2.5 and meteorological variables. The results showed that the PM2.5 concentrations were in the range of 16–195 μg/m3 in 2020. The high level of PM2.5 in Lampang, Chiang Rai, and Chiang Mai provinces was in the range of 150 to 195 μg/m3 from January to May. Favorable meteorological conditions included low wind and relative humidity, and high temperatures contributed to high PM2.5 concentrations in northern Thailand. Domestic burning and burning in neighboring countries contribute to huge amounts of smoke that cause low visibility in northern Thailand, especially at 1 km above ground level, with a reduced visibility in the range of 70–90% for all provinces in April.

How much urban air quality is affected by local emissions: A unique case study from a megacity in the Pearl River Delta, China

In March 2022, the resurgence of COVID-19 cases in Shenzhen, a megacity in the Pearl River Delta (PRD) region of China, led to unusual restrictions on anthropogenic activities within a single city, in contrast to the restrictions COVID-19 caused on a national scale at the beginning of 2020. In this unique event, we found that only under unfavorable meteorological conditions did substantial urban local emission reductions have an impact on air pollutant changes (−42.4%–6.6%), whereas the deweathered changes were very small (−8.3%–3.4%) under favorable meteorological conditions. Primary anthropogenic pollutants, such as NO2, toluene, BC, and primary organic aerosol (POA), responded most considerably to emission reductions from early morning to noon during unfavorable meteorological days; for secondary organic aerosol (SOA), regulating the daytime total oxidant (Ox = O3 + NO2) was found to be more effective than controlling its precursors within the city scale, whereas secondary nitrate displayed the opposite trend. Since Ox changed little during the urban lockdown despite the remarkable decrease in precursors, it is emphasized that regionally coordinated control of VOCs and NOx is necessary to effectively reduce Ox levels. In addition, Shenzhen's NOx emission reduction efforts should be sustained in order to control PM2.5 and O3 pollution synergistically for long-term attainment.

Impact Analysis of Super Typhoon 2114 ‘Chanthu’ on the Air Quality of Coastal Cities in Southeast China Based on Multi-Source Measurements

The northward typhoon configuration along the southeast coast of China (TCN-SEC) is one of the key circulation patterns influencing the coastal cities in southeast China (CCSE). Here, we analyzed the air quality in CCSE during the high-incidence typhoon period from 2019 to 2021. Multi-source measurements were carried out to explore the impact of super typhoon 2114 ‘Chanthu’ on the air quality in CCSE. The results showed that the TCN-SEC and its surrounding weather situation had a favorable impact on the increase in pollutant concentration in CCSE, especially on the increase in O3 concentration. From 13 September to 17 September 2021, affected by the cyclonic shear in the south of super typhoon 2114 ‘Chanthu,’ the strong wind near the ground, stable relative humidity, strong precipitation, and the significantly reduced wind speed had a substantial effect on PM10, PM2.5, SO2, and NO2 concentrations. Calm and light air near the ground, weak precipitation, high daily maximum temperatures, and minimum relative humidity may provide favorable meteorological conditions for the accumulation of O3 precursors and photochemical reactions during the day, resulting in the daily peak values of O3 exceeding 160 μg/m3. The evolution of wind, relative humidity, and boundary layer height could play an important role in the variations in PM10 and PM2.5 concentrations by influencing pollutant accumulation or diffusion. It was suggested that the atmospheric structure of horizontal stability and vertical mixing below 1500 m could play a significant role in the accumulation and vertical distribution of ozone. The results highlight the important role of typhoons in the regional environment and provide a scientific basis for further application of multi-source observation data, as well as air pollution control.

Quantitative evidence from VOCs source apportionment reveals O3 control strategies in northern and southern China

Ground-level ozone (O3) pollution has received widespread attention because its rising trend and adverse ecological impacts. However, the extremely strong photochemical reactions of its precursor volatile organic compounds (VOCs) increase the difficulty of reducing VOCs emissions to alleviate O3. Here, we carried out a one-year comprehensive observation in two representative cities, Tianjin (TJ, Northern China) and Guangzhou (GZ, Southern China). By revealing the concentration characteristics of three different types of VOCs, i.e., initial VOCs without photochemical reaction (In-VOCs), consumed VOCs (C-VOCs), and measured VOCs after the reaction (M-VOCs), we elucidated the important role of C-VOCs in the formation of O3. Although the overall trends were similar in both cities, the average concentration level of VOCs in GZ was 8.2 ppbv higher than that in TJ, and the photochemical loss of VOCs was greater by 2.2 ppbv. In addition, various drivers affecting O3 generation from C-VOCs were specifically explored, and it was found that most alkenes of TJ were key substances for rapid O3 formation compared to aromatics of GZ. Meanwhile, favorable meteorological conditions such as high temperature (T > 31 °C in TJ, and T > 33 °C in GZ), low relative humidity (56% in TJ and 45% in GZ), and stable atmospheric environment (proper pressure and gentle wind speed) also contribute to the generation of O3. More importantly, we combined chemical kinetics and receptor model to quantify the three-type VOCs source contributions and assess the potential impact of C-VOCs sources on O3 production, thus proposing environmental abatement technologies corresponding to the three types of VOCs. The differences in the comparison results of the three-type VOCs highlight the need to reduce O3 pollution from C-VOCs sources, which provides insights for future clean air policies development.

Pale tussock moth, Calliteara pudibunda (Linnaeus, 1758) (Lepidoptera; Erebidae) with a focus on its situation in Türkiye

AbstractCalliteara pudibunda is a univoltine, polyphagous and native species producing periodic outbreaks which have been recorded only in Europe so far. Its larvae feed on the foliage of beech, oak and several other deciduous and coniferous trees. It is very widespread in Eurasia. In Europe, it is found between the 34th and 60th parallels. In Türkiye, it occurs mainly in coastal regions. Its outbreak range had been thought to be confined between the 48th and 57th parallels in Europe until the last two decades when outbreaks occurred in Italy and Türkiye. Therefore, the southern limit of its outbreak range can be updated as the 36th parallel. The outbreaks recur every 20–30 years, typically continue for 1–2 years, and end suddenly. Favourable meteorological conditions and a temporary rarity of parasitoids seem to be the main causes of the outbreaks. The damage on hosts is not evident until the third larval instar. The affected hosts may grow new shoots the next spring, as the larvae usually do not attack the terminal shoots. Increment loss is possible, but it may not be economically significant per se. However, tree mortality can occur with the combined effects of other stress factors. The impact of parasitoids and predators during the outbreaks is low. There are also fungal species identified from larvae and pupae, some of which might have significant potential in pest management. Additionally, Bacillus thuringiensis var. kurstaki (Btk), polyhedrosis viruses and light traps can potentially be used, although management practices are not recommended in C. pudibunda outbreaks.

Drivers of 2015–2021 trends in cold winter surface PM2.5 in the Harbin-Changchun megalopolis in China: Meteorology vs. anthropogenic emission

Harbin-Changchun megalopolis (HCM) is a typical representative of the cold urban agglomeration region in China. Although the average annual PM2.5 concentration has experienced an evolutionary process continuous deterioration to gradual improvement in the past decade, but severe haze episodes still occur during cold winter periods. WRF-CMAQ model and observed dataset of surface PM2.5 concentration were conducted in this study to identify the drivers of 2015–2021 trends in cold winter surface PM2.5 in the HCM by separating contributions from anthropogenic emissions and meteorology changes. Meteorological condition change was the dominant driver of 2015–2021 trends in cold winter surface PM2.5 in the HCM. The years with most unfavorable, typical, and most favorable meteorological conditions for PM2.5 concentration reduction during January from 2015 to 2021 for the whole HCM region were 2020, 2017, and 2018, respectively. The major controlling meteorological factors that affect the surface PM2.5 concentration change were relative humidity, maximum wind direction and speed in cold winter in the HCM. In addition, we found that the emission cut policy began to play a practical role in the air quality improvement in the HCM from year of 2018. The emission reduction during the 2017–2021 resulted in an approximately 19% (15.7 μg/m3) decrease of PM2.5 concentrations in January. Furthermore, sensitivity experiments demonstrated that residential emission cut was the key measures for future air quality improvement in cold winter in the HCM.

Spatial distribution and temporal variation of biomass burning and surface black carbon concentrations during summer (2015‒2021) in India.

Historical biomass burning in summer season (April‒June, during 2015‒2021) was assessed by studying active fire spot data recorded by the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard NASA/NOAASuomi NPP satellite and mapping the same over Indian landmass. The fire spots often formed regional clusters and most profusely covered the states of Odisha, Chhattisgarh, Andhra Pradesh, Telengana, Madhya Pradesh, Maharashtra, Jharkhand, Karnataka, Punjab, Uttar Pradesh, Haryana, Gujarat, Tamil Nadu, Manipur, Nagaland, and Mizoram during April but their number decreased conspicuously in May and further in June. Forward movements of air masses potentially carrying fire-induced air pollutants from five principal fire cluster regions (northern, south eastern, western, north-eastern, and central) of India during April and May in2021 were traced by 6-day forward airtrajectory modelling. It was observed that many parts of India were the recipients of air coming from the above principal fire clusters. In each year, the surface mass concentration of black carbon (BC), one of the most prominent markers of biomass burning, was higher in April over May and June in the affected regions, commensurate with the most active period of fire. The BC surface mass concentrations progressively declined thereafter in May and June with decreasing number of active fire spots along with declining average monthly height of the planetary boundary layer (PBL), indicating integral connection of surface BC levels with biomass burning. The study suggests that in spite of more favourable meteorological conditions in summer, extensivebiomass burning may have hada crucial role to play in perturbing local and regional air quality over India by generatingBC and other air pollutants.

Assessment of the Steering Precision of a UAV along the Flight Profiles Using a GNSS RTK Receiver

Photogrammetric surveys are increasingly being carried out using Unmanned Aerial Vehicles (UAV). Steering drones along the flight profiles is one of the main factors that determines the quality of the compiled photogrammetric products. The aim of this article is to present a methodology for performing and processing measurements, which are used in order to determine the accuracy of steering any drone along flight profiles. The study used a drone equipped with a Global Navigation Satellite System (GNSS) Real Time Kinematic (RTK) receiver. The measurements were performed on two routes which comprised parallel profiles distant from each other by 10 m and 20 m. The study was conducted under favourable meteorological conditions (windless and sunny weather) at three speeds (10 km/h, 20 km/h and 30 km/h). The cross track error (XTE), which is the distance between a UAV’s position and the flight profile, calculated transversely to the course, was adopted as the accuracy measure of steering a UAV along the flight profiles. Based on the results obtained, it must be concluded that the values of XTE measures for two representative routes are very similar and are not determined by the flight speed. The XTE68 measure (p = 0.68) ranged from 0.39 m to 1.00 m, while the XTE95 measure (p = 0.95) ranged from 0.60 m to 1.22 m. Moreover, analyses demonstrated that the statistical distribution of the XTE measure was most similar to the gamma and Weibull (3P) distributions.

Physico-Chemical Properties and Deposition Potential of PM2.5 during Severe Smog Event in Delhi, India.

The present work studies a severe smog event that occurred in Delhi (India) in 2017, targeting the characterization of PM2.5 and its deposition potential in human respiratory tract of different population groups in which the PM2.5 levels raised from 124.0 µg/m3 (pre-smog period) to 717.2 µg/m3 (during smog period). Higher concentration of elements such as C, N, O, Na, Mg, Al, Si, S, Fe, Cl, Ca, Ti, Cr, Pb, Fe, K, Cu, Cl, P, and F were observed during the smog along with dominant organic functional groups (aldehyde, ketones, alkyl halides (R-F; R-Br; R-Cl), ether, etc.), which supported potential contribution from transboundary biomass-burning activities along with local pollution sources and favorable meteorological conditions. The morphology of individual particles were found mostly as non-spherical, including carbon fractals, aggregates, sharp-edged, rod-shaped, and flaky structures. A multiple path particle dosimetry (MPPD) model showed significant deposition potential of PM2.5 in terms of deposition fraction, mass rate, and mass flux during smog conditions in all age groups. The highest PM2.5 deposition fraction and mass rate were found for the head region followed by the alveolar region of the human respiratory tract. The highest mass flux was reported for 21-month-old (4.7 × 102 µg/min/m2), followed by 3-month-old (49.2 µg/min/m2) children, whereas it was lowest for 21-year-old adults (6.8 µg/min/m2), indicating babies and children were more vulnerable to PM2.5 pollution than adults during smog. Deposition doses of toxic elements such as Cr, Fe, Zn, Pb, Cu, Mn, and Ni were also found to be higher (up to 1 × 10-7 µg/kg/day) for children than adults.

Quantifying the drivers of surface ozone anomalies in the urban areas over the Qinghai-Tibet Plateau

Abstract. Improved knowledge of the chemistry and drivers of surface ozone over the Qinghai-Tibet Plateau (QTP) is significant for regulatory and control purposes in this high-altitude region in the Himalayas. In this study, we investigate the processes and drivers of surface ozone anomalies (defined as deviations of ozone levels relative to their seasonal means) between 2015 and 2020 in urban areas over the QTP. We separate quantitatively the contributions of anthropogenic emissions and meteorology to surface ozone anomalies by using the random forest (RF) machine-learning model-based meteorological normalization method. Diurnal and seasonal surface ozone anomalies over the QTP were mainly driven by meteorological conditions, such as temperature, planetary boundary layer height, surface incoming shortwave flux, downward transport velocity and inter-annual anomalies were mainly driven by anthropogenic emission. Depending on region and measurement hour, diurnal surface ozone anomalies varied over −27.82 to 37.11 µg m−3, whereas meteorological and anthropogenic contributions varied over −33.88 to 35.86 µg m−3 and −4.32 to 4.05 µg m−3 respectively. Exceptional meteorology drove 97 % of surface ozone non-attainment events from 2015 to 2020 in the urban areas over the QTP. Monthly averaged surface ozone anomalies from 2015 to 2020 varied with much smaller amplitudes than their diurnal anomalies, whereas meteorological and anthropogenic contributions varied over 7.63 to 55.61 µg m−3 and 3.67 to 35.28 µg m−3 respectively. The inter-annual trends of surface ozone in Ngari, Lhasa, Naqu, Qamdo, Diqing, Haixi and Guoluo can be attributed to anthropogenic emissions in 95.77 %, 96.30 %, 97.83 %, 82.30 %, 99.26 % and 87.85 %, and meteorology in 4.23 %, 3.70 %, 2.17 %, 3.19 %, 0.74 % and 12.15 % respectively. The inter-annual trends of surface ozone in other cities were fully driven by anthropogenic emission, whereas the increasing inter-annual trends would have larger values if not for the favorable meteorological conditions. This study can not only improve our knowledge with respect to spatiotemporal variability of surface ozone but also provide valuable implications for ozone mitigation over the QTP.

Impacts of the COVID-19 lockdown in China on new particle formation and particle number size distribution in three regional background sites in Asian continental outflow

Despite the curtailment of atmospheric condensing precursor gases during the Coronavirus disease 2019 (COVID-19) lockdown (LD) period, unexpected haze events via the formation of new particles and their subsequent growth have been identified. This study investigated the impact of emission reduction during the Chinese LD period on the new particle formation (NPF) frequency and corresponding particle number size distribution (PNSD) at three regional background atmospheric monitoring sites in the western coastal areas of the Korean Peninsula. During this duration, the number concentrations of the nucleation- (<25 nm) and accumulation-mode (>90 nm) particles significantly decreased in Baengryeong (BRY), showing decreases of 34% and 29%, respectively. Unlike BRY, the PNSD in Anmyeon (AMY), which is influenced by nearby industrial emissions, remained nearly unchanged during the LD period, possibly because the reduction in industrial emissions was not significant during the social distancing period enforced by Korea. Bongseong (BOS) showed a similar variation to that of BRY; however, the magnitude of the reduction was weaker because of its higher altitude compared to other sites. The cyclostationary empirical orthogonal function technique was applied to the measured PNSDs at the three sites to objectively classify NPF events. Because mode 1 of cyclostationary loading vectors commonly represented the typical diurnal variation of PNSD during regional NPF events at three sites, mode 1 of the corresponding principal component time series was used for NPF classification. The NPF frequency decreased by 7%, 1%, and 7% in BRY, AMY, and BOS, respectively, despite favorable meteorological conditions, such as increased temperature and insolation during the LD period. The diurnal variation in the sulfuric acid (H2SO4) proxy implied that the H2SO4 proxy acted as a determining factor for NPF events during the NPF occurrence time (8–12 local hours) in AMY and BOS; however, NPF occurrence in BRY was not connected to the H2SO4 proxy level. This suggests that BRY was more likely to be influenced by the reduction in organic species in the continental upwind regions, while the occurrence of NPF events in AMY and BOS can be suppressed in association with the distinct reduction in inorganic compounds represented by the H2SO4 proxy during the LD period.