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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.
  • 113
  • 19 Dec 2023
Topic Review
Near-Surface Wind
Near-surface wind is one of the most important meteorological parameters. Near-surface wind grid products are an important part of live analysis products . Reliable near-surface wind products have an important role in the monitoring, prediction, and study of wind disasters. The evaluation of near-surface wind products can provide the direction for improving the data quality for Hainan, provide basic support for fine-grid forecasting and meteorological services, and help to reduce the losses that are caused by wind disasters.
  • 777
  • 09 Jul 2021
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.
  • 223
  • 21 Oct 2022
Topic Review
NASA Micropulse Lidar Rain Algorithm
Precipitation modifies atmospheric column thermodynamics through the process of evaporation and serves as a proxy for latent heat modulation. For this reason, a correct precipitation parameterization (especially for low-intensity precipitation) within global scale models is crucial. In addition to improving our modeling of the hydrological cycle, this will reduce the associated uncertainty of global climate models in correctly forecasting future scenarios, and will enable the application of mitigation strategies. In this study we present a proof of concept algorithm to automatically detect precipitation from lidar measurements obtained from the National Aeronautics and Space Administration Micropulse lidar network (MPLNET). 
  • 777
  • 09 Feb 2021
Topic Review
Nanoparticle Number Concentration
The entry analyzes suspended particles number concentrations of 61 size fractions (184 nm to 17,165 nm) in the air at a traffic location. The average course of the individual fractions was analyzed at various intervals – daily, weekly, monthly and annually, in the period between 2017 and 2019. The data was then used to calculate the arithmetic mean for all the fractions (MS Excel, R) and then using a proprietary web application, heatmaps were constructed. The obtained results showed significant differences in both the annual and daily variation of number concentrations between the individual fractions differing in particle size. In the case of the annual variation, one can see a greater variability of smaller particles, which is most likely due to the source of the actual suspended particles. Meteorological and dispersion conditions are found as important factors for suspended particle concentrations. These can lead to significant differences from year to year. However, a comparison between 2018 and 2019 showed that even though the average absolute number concentrations can differ between years, the actual relative number concentrations, i.e. the ratios between the individual fractions remain very similar. In conclusion it can be said that the difference between the number concentration variation of the size fractions depends on both the actual pollution sources (especially in the long-term, i.e. the annual variation) and the actual size of the particles, which plays a role especially in the short-term (daily, weekly variation).
  • 602
  • 27 Oct 2020
Topic Review
Molecular to Meteorological
The path from molecular to meteorological scales begins with the persistence of molecular velocity after collision inducing symmetry breaking, from continuous translational to scale invariant, associated with the emergence of hydrodynamic behaviour in a Maxwellian (randomised) population undergoing an anisotropic flux. The statistical multifractal formulation of observed atmospheric variability enables the examination of turbulence. The unexpected correlation between the intermittency of temperature and the ozone photodissociation rate in the lower Arctic stratosphere led to an analysis of the role of Gibbs free energy in the general circulation of the atmosphere, and a suggestion to solve the persistent cold bias in its siumlation by free running numerical models.
  • 353
  • 12 Apr 2022
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.
  • 89
  • 23 Nov 2023
Topic Review
Meteorological Conditions on Riverbed Dust Aerosol in Taiwan
Extremely high concentrations of dust particles are occasionally generated from the riverbeds of Taiwan, affecting the visibility and traffic safety of the local and nearby areas. The condition is most severe during the winter monsoon when surface wind is strong.
  • 328
  • 17 Jan 2022
Topic Review
Mercury in the Southern Hemisphere
Mercury is a toxic pollutant that can negatively impact the population’s health and the environment. The research on atmospheric mercury is of critical concern because of the diverse process that this pollutant suffers in the atmosphere as well as its deposition capacity, which can provoke diverse health issues.
  • 325
  • 26 Aug 2022
Topic Review
Mediterranean Drought: Regional Exceptional Datasets
To define such drought events and their characteristics, separate analyses based on three drought indices were performed at 12-month timescale: the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Reconnaissance Drought Index (RDI). A multivariate combined drought index (DXI) was developed by merging the previous three indices for more understanding of droughts’ features at the country and subregional levels. Principal component analysis (PCA) was used to identify five different drought subregions based on DXI-12 values for 312 Mediterranean stations and a new special score was defined to classify the multi-subregional exceptional drought events across the Mediterranean Basin (MED). The results indicated that extensive drought events occurred more frequently since the late 1990s, showing several drought hotspots in the last decades in the southeastern Mediterranean and northwest Africa. In addition, the results showed that the most severe events were more detected when more than single drought index was used. 
  • 642
  • 11 Aug 2021
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