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Topic Review

Ambient Nanoparticles Mapping in Thailand

Nanoparticles (NPs), nanoaerosols (NAs), ultrafine particles (UFPs), and PM0.1 (diameters ≤ 0.1 µm or 100 nm) are used interchangeably in the field of atmospheric studies. PM0.1 mainly originate from combustion processes such as in motor vehicles. The highest mass concentration of PM0.1 occurs during the dry season, in which open fires occur in some regions of Thailand. The northern area of the country has higher PM0.1 mass concentrations, followed by the central and southern areas. Carbonaceous nanoaerosols are produced during normal periods, and the proportions of organic to elemental carbon and char to soot suggest that these originate from motor vehicles. However, in haze periods, biomass fires can also produce carbon-containing particles. PM0.1 pollution from local and cross-border countries also needs to be considered. The overall conclusions reached will likely have a beneficial long-term impact on achieving a blue sky over Thailand through the development of coherent policies and managing new air pollution challenges and sharing knowledge with a broader audience.

687
11 Jan 2023

Topic Review

Methodologies for Wind Field Reconstruction in the U-SPACE

The main methodologies used to reconstruct wind fields in the U-SPACE have been analyzed. The SESAR U-SPACE program aims to develop an Unmanned Traffic Management system with a progressive introduction of procedures and services designed to support secure access to the air space for a large number of drones. Some of these techniques were originally developed for reconstruction at high altitudes, but successively adapted to treat different heights. A common approach to all techniques is to approximate the probabilistic distribution of wind speed over time with some parametric models, apply spatial interpolation to the parameters and then read the predicted value.

679
23 Nov 2023

Topic Review

EU Policy Landscape in Climate-Related Extreme Events

Climate-related extreme events are part of disaster risk reduction policies ruled at international, EU, and national levels, covering various sectors and features such as awareness-raising, prevention, mitigation, preparedness, monitoring and detection, response, and recovery.

666
24 Jan 2022

Topic Review

Anaerobic Co-Digestion of Primary Sludge and Biowastes

Primary sludge is a valuable substrate for anaerobic digestion as it contains a higher percentage of fatty acids and lipids compared to secondary sludge, although its carbon-to-nitrogen ratio is relatively low due to its inherent deficiency of carbon. This limiting factor of C/N ratio can be overwhelmed by the co-digestion of primary sludge with organic fractions such as agricultural byproducts and municipal solid wastes. The operating principle of this practice is based on the fact that organic fractions such as agricultural byproducts contain a high percentage of carbon and a low percentage of nitrogen, so the co-digestion of primary sludge with different organic fractions, such as animal manure, agricultural residues, organic fractions of municipal waste, or vegetable residues, may improve the balance of nutrients, provide buffering capacity, adjust the C/N ratio, reduce the concentration of ammonia, and hence its inhibitory effects, and overall promote the process of methanogenesis.

622
26 Feb 2024

Topic Review

National Emissions Standards Act

The National Emissions Standards Act, officially known as the Motor Vehicle Air Pollution Control Act (Pub.L. 89–272), is a 1965 amendment to the U.S. Clean Air Act of 1963. The amendment set the first federal vehicle emissions standards, beginning with the 1968 models. These standards were reductions from the 1963 emissions: 72% reduction for hydrocarbons, 56% reduction for carbon monoxide, and 100% reduction for crankcase hydrocarbons. The impact the regulatory standards will have on air quality in the future, as well as the potential characteristics of the vehicle fleet can be analyzed with the use of roadway air dispersion models. The U.S. Environmental Protection Agency (EPA) is a department specific to the Clean Air Act. Its purpose is to make sure the amount of air pollution emitted stays inside the standards set by the U.S. Each state is required to have a state implementation plan (SIPs) that clearly indicates how it will enforce the regulations of the Clean Air Act. The states have to create regulations of their own that also adhere to the guidelines of the U.S. regulations; in order to do so, they must hold hearings so the public can contribute ideas and provide feedback.

607
21 Oct 2022

Topic Review

Semantic Segmentation Networks for Forest Applications

Deforestation remains one of the key concerning activities around the world due to commodity-driven extraction, agricultural land expansion, and urbanization. The effective and efficient monitoring of national forests using remote sensing technology is important for the early detection and mitigation of deforestation activities. Deep learning techniques have been vastly researched and applied to various remote sensing tasks, whereby fully convolutional neural networks have been commonly studied with various input band combinations for satellite imagery applications, but very little research has focused on deep networks with high-resolution representations, such as HRNet.

562
08 Jan 2024

Topic Review

New Ways to Modelling and Predicting Ionosphere Variables

The new way of thinking science from Newtonian determinism to nonlinear unpredictability and the dawn of advanced computer science and technology can be summarized in the words of the theoretical physicist Michel Baranger, who, in 2000, said in a conference: “Twenty-first-century theoretical physics is coming out of the chaos revolution; it will be about complexity and its principal tool will be the computer.”. This can be extended to natural sciences in general. Modelling and predicting ionosphere variables have been considered since many decades as a paramount objective of research by scientists and engineers. The new approach to natural sciences influenced also ionosphere research. Ionosphere as a part of the solar–terrestrial environment is recognised to be a complex chaotic system, and its study under this new way of thinking should become an important area of ionospheric research, particularly with the addition of machine learning techniques.

431
19 Dec 2023

Topic Review Peer Reviewed

Quantifying Methane Emission Rates Using Downwind Measurements

This entry describes the methods used to quantify methane emissions from either point or area sources using downwind methods. The methods described could be used as a practical guide to quantify emissions of any trace gas type from either a point or area emission source. Methane is a relatively strong greenhouse gas, its GWP is 25 times larger than CO2 over a 100-year period, and an increase in methane anthropogenic emissions has been correlated to a changing global climate. Emission estimates that are calculated and used for national inventories are usually derived from bottom-up approaches, however there is now an increasing pressure for these to be validated by direct measurement. Calculating emission rates from downwind measurements has proven to be a versatile and relatively simple approach for direct measurement. Downwind measurement method descriptions are presented here as a practicable guide to quantifying point and area source emissions. Emission quantification is a two-stage process where methane concentration and meteorological data must be measured downwind of a source and then converted to emissions using an atmospheric dispersion model. Only four technology types currently measure in the range typical of downwind methane concentrations: metal oxide sensors, non-dispersive infrared sensors, tunable diode laser absorption spectrometers and optical cavity instruments. The choice of methane measurement is typically determined by the size of the emission source, location and the budget of the project. Meteorological data are essential to quantifying emissions, especially regarding wind speed and direction. In most cases, simple atmospheric dispersion approaches can be used to quantify both area and point emissions using these downwind measurements. Emissions can be generated using limited data (only methane concentration, wind speed, wind direction, and locations are necessary), but quantification uncertainty can be reduced using more input data. Site selection and location of instrument deployment are essential because quantification approaches assume a flat fetch (no aerodynamic obstructions) and constant wind fields. When modeling assumptions are violated, quantification uncertainty can range between +250% and −100% of the actual emission rate. At present there, is no happy medium between modeling complexity and computational time, and this remains the biggest challenge for downwind emission quantification.

147
20 May 2025

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