Evolution and meteorological causes of fine particulate explosive growth events in Beijing, China, from 2013 to 2017

Based on online observations of fine particulate matter(PM2.5) for five consecutive years from January 2013 to December 2017 in Beijing, combined with simultaneous measurement of gaseous precursors and meteorological parameters, the evolution and meteorological causes of fineparticle explosive growth(FPEG) events were analyzed. During the 5-year observation period,132 FPEG events were observed and these events were further divided into three types(3-, 6-, and 9-h events) according to their evolution duration. The majority of FPEG events were observed in winter under the conditions of higher gas precursor concentrations and unfavorable meteorological conditions. The average concentration of PM2.5 during winter FPEG events changed little from 2013 to 2016, whereas it decreased significantly in 2017, in accordance with the similar variation of gaseous species(SO2, NO2, and CO). In addition, the higher wind speeds and lowest relative humidity observed in 2017 were also conducive to the decrease in PM2.5. The evolutions of FPEG events and normal haze episodes were analyzed, revealing that the rate of increase in NO2 was much greater than that of SO2, suggesting more of a contribution from mobile sources than stationary sources. The polar Plot results suggest that the transportation from the southeast area of Beijing plays a major role in the formation of 3-h events, whereas local emissions is the main contributory factor for 9-h events and normal haze episodes. However, further quantitative analysis regarding the contributions of these factors is still needed.

Relative Contributions of Boundary-Layer Meteorological Factors to the Explosive Growth of PM2.5 during the Red-Alert Heavy Pollution Episodes in Beijing in December 2016

Based on observations of urban mass concentration of fine particulate matter smaller than 2.5 μm in diameter （PM2.5）, ground meteorological data, vertical measurements of winds, temperature, and relative humidity （RH）, and ECMWF reanalysis data, the major changes in the vertical structures of meteorological factors in the boundary layer （BL） during the heavy aerosol pollution episodes （HPEs） that occurred in winter 2016 in the urban Beijing area were analyzed. The HPEs are divided into two stages： the transport of pollutants under prevailing southerly winds, known as the transport stage （TS）, and the PM2.5 explosive growth and pollution accumulation period characterized by a temperature inversion with low winds and high RH in the lower BL, known as the cumulative stage （CS）. During the TS, a surface high lies south of Beijing, and pollutants are transported northwards. During the CS, a stable BL forms and is characterized by weak winds, temperature inversion, and moisture accumulation. Stable atmospheric stratifica- tion featured with light/calm winds and accumulated moisture （RH 〉 80%） below 250 m at the beginning of the CS is closely associated with the inversion, which is strengthened by the considerable decrease in near-surface air temperat- ure due to the interaction between aerosols and radiation after the aerosol pollution occurs. A significant increase in the PLAM （Parameter Linking Aerosol Pollution and Meteorological Elements） index is found, which is linearly re- lated to PM mass change. During the first 10 h of the CS, the more stable BL contributes approximately 84% of the explosive growth of PM2.5 mass. Additional accumulated near-surface moisture caused by the ground temperature de- crease, weak turbulent diffusion, low BL height, and inhibited vertical mixing of water vapor is conducive to the sec- ondary aerosol formation through chemical reactions, including liquid phase and heterogeneous reactions, which fur- ther increases the PM2.5 concentration levels. The contribution of these reaction mechanisms to the explosive growth of PM2,5 mass during the early CS and subsequent pollution accumulation requires further investigation.

The Explosive Growth of TMT

As the technology, media and telecommunications (TMT) convergence gains traction worldwide, venture capitalists look to China and its growing hi-tech consumer base as the next big

Effect of toroidal mode coupling on explosive dynamics of m/n=3/1 double tearing mode

The CLT code was used to quantitatively study the impact of toroidal mode coupling on the explosive dynamics of the m/n=3/1 double tearing mode.The focus of this study was on explosive reconnection processes,in which the energy bursts and the main mode no longer dominates when the separation between two rational surfaces is relatively large in the medium range.The development of higher m and n modes is facilitated by a relatively large separation between two rational surfaces,a small q_(min)(the minimum value of the safety factor),or low resistivity.The relationships between the higher m and n mode development,explosive reconnection rate,and position exchange of 3/1 islands are summarized for the first time.Separation plays a more important role than q_(min)in enhancing the development of higher m and n modes.At a relatively large separation,the good development of higher m and n modes greatly reduces the reconnection rate and suppresses the development of the main mode,resulting in the main mode not being able to develop sufficiently large to generate the position changes of 3/1 islands.

Phenomenological Models of the Global Demographic Dynamics and Their Usage for Forecasting in 21st Century

A great discovery made by H. von Foerster, P. M. Mora and L. W. Amiot was published in a 1960 issue of “Science”. The authors showed that existing data for calculating the Earth’s population in the new era (from 1 to 1958) could be described with incredibly high proximity by a hyperbolic function with the point of singularity on 13 November 2026. Thus, empirical regularity of the rise of the human population was established, which was marked by explosive demographic growth in the 20th century when during only one century it almost quadrupled: from 1.656 billion in 1900 to 6.144 billion in 2000. Nowadays, the world population has already overcome 7.8 billion people. Immediately after 1960, an active search for phenomenological models began to explain the mechanism of the hyperbolic population growth and the following demographic transition designed to stabilize its population. A significant role in explaining the mechanism of the hyperbolic growth of the world population was played by S. Kuznets (1960) and E. Boserup (1965), who found out that the rates of technological progress historically increased in proportion to the Earth’s population. It meant that the growth of the population led to raising the level of life-supporting technologies, and the latter in its turn enlarged the carrying capacity of the Earth, making it possible for the world population to expand. Proceeding from the information imperative, we have developed the model of the demographic dynamics for the 21st century for the first time. The model shows that with the development and spread of Intelligent Machines (IM), the number of the world population reaching a certain maximum will then irreversibly decline. Human depopulation will largely touch upon the most developed countries, where IM is used intensively nowadays. Until a certain moment in time, this depopulation in developed countries will be compensated by the explosive growth of the population in African countries located south of the Sahara. Calculations in our model reveal that the peak of the human population of 8.52 billion people will be reached in 2050, then it will irreversibly go down to 7.9 billion people by 2100, if developed countries do not take timely effective measures to overcome the process of information depopulation.