环境保护署

In the polar regions, the extreme cold and dark atmosphere of the winter season imposes stringent conditions on the planetary boundary layer (PBL) leading to limited vertical atmospheric mixing and increasing the severity of air pollution episodes. Understanding the physical and chemical transformations affecting air pollution critically depends on our ability to accurately describe the dynamics of the PBL. This requires an adequate combination of modeling, ground-based observations, and vertical profile measurement systems to assess emission dispersion and transport in stratified environments. We present an overview of the meteorological conditions and PBL observations collected during the Alaskan Layered Pollution and Chemical Analysis (ALPACA) field experiment in Fairbanks, Alaska, in winter 2022. Surface and vertical profile observations of radiation, turbulence, dynamics, and atmospheric composition were collected to account for surface and elevated emissions. The study area is the Tanana Valley in the interior of Alaska, which experiences persistent synoptic anticyclonic conditions resulting in stagnant flow and limited ventilation, exacerbating air pollution levels. These conditions are interspersed with periodic transits of cyclonic air masses influencing the PBL through radiative forcing that erodes low-level temperature inversion layers and mixes local air masses into the free troposphere. This paper highlights the research objectives, experimental findings, and first results linking meteorological conditions with the observed structure and composition of the PBL under the challenging experimental conditions of the Alaskan winters. It also highlights the need for integrated surface and profiling observations of PBL dynamics and composition, which are critical for advancing across-scale modeling and enhancing predictive capabilities for air pollution episodes locally and throughout the Arctic air shed. SIGNIFICANCE STATEMENT: This article provides an overview of the meteorology during the Alaskan Layered Pollution and Chemical Analysis (ALPACA)-2022 winter field experiment. It also presents observations designed to better understand the physical processes influencing the planetary boundary layer (PBL) and their role in wintertime Arctic air pollution. It describes the synoptic meteorological conditions throughout the experiment and the diverse instrumental platforms used to study the dynamics and composition of the Arctic polluted PBL for the first time. The article emphasizes the importance of multi-instrumental platforms to improve understanding of the PBL composition and dynamics in the context of Arctic air pollution. This is particularly relevant in conditions with limited photochemistry and in areas experiencing very cold, stable environments that exacerbate pollution levels. The observations are used to improve meteorological and air quality model simulations.

Ice crystals in tropical cyclones (TCs) remain infrequently observed and difficult to model using Eulerian microphysics parameterizations. To better understand TC eyewall ice crystal processes, the Ice Crystal Trajectory Growth (ICTG) model, previously applied to an idealized squall line, was used to simulate Lagrangian ice crystal trajectories in a Weather Research and Forecasting (WRF) model simulation of Hurricane Harvey (2017). ICTG includes laboratory-informed growth equations capable of simulating complex crystal morphologies and is used to assess how initial altitude, radius, and size influence crystal growth and advection. We introduce an initialization technique where the initial crystal locations and sizes best match WRF microphysical fields. Results showed that the initial crystal altitude was most important in determining final mass, shape, location, and likelihood of sublimation; initial size and radial distance played secondary but noticeable roles. The largest final masses began at 8 km altitude and grew predominantly in the dendritic growth zone (-12 to -18C) resulting in plate-like crystals. Crystals that accumulated the most rime mass began between 7 and 9 km altitude, while crystals above 9 km experienced more radial outward transport often leading to sublimation particularly for smaller crystals. Results using a "super-particle" method showed that most of the ice mass reached the melting level within or just beyond the eyewall with a large diversity of crystal shapes and sizes. The greatest radial extent of ice was 150 km, supporting recent research suggesting the eyewall is not a dominant source of TC outflow condensate.

The relevance of choosing small towns as a research object is due to the fact that improving the lives of their residents has been declared a strategic priority for the state. This issue is being implemented within the framework of the federal project «Creating a comfortable urban environment» of the national project «Infrastructure for Life». The subject of the study is the regional policy in the Russian Federation in relation to small towns in the existing model of fiscal federalism. The purpose of the work is to analyze the current problems of small towns as objects of regional policy in the context of fiscal federalism and to develop recommendations for their leveling. The research applied methods of systematization, analysis of the regulatory framework and dynamics of statistical indicators. In-depth expert interviews with key representatives of various spheres of management in small towns of the Russian Federation were used as an information base. As a result of the study, the problems of the development of small towns in the Russian Federation are actualized, descriptive statistics of individual indicators of small towns are calculated, the primary problem of small towns in the context of budgetary federalism is identified – the insufficiency of the revenue side of the local budget, promising areas of regional state policy in relation to small towns are identified within the framework of the existing model of budgetary federalism. The practical significance of the study lies in the developed recommendations for optimizing regional policy in relation to small towns, which can be used by the relevant authorities. The conclusion is made: taking into account the uneven distribution of small towns across the territory of the Russian Federation, their development will enhance the process of economic alignment of the regions.

Ambient Particulate Matters (PM10, PM2.5 and PM0.1) were investigated at Shinjung station in New Taipei City, Taiwan. Samples were collected simultaneously using a dichotomous sampler (Andersen Model SA-241) and a MOUDI (MSP Model 110) over a 24-h period from May 2011 to November 2011 at Shinjung station. Samples were analyzed for metallic trace elements using ion coupled plasma mass spectroscopy (ICP-MS) and ionic compounds by ion chromatography (IC). The average concentrations of PM10, PM2.5 and PM0.1 were found to be 39.45 ± 11.58, 21.82 ± 7.50 and 1.42 ± 0.56 μg/m3, respectively. Based on the chemical information, positive matrix factorization (PMF) was used to identify PM sources. A total of five source types were identified, including soil dust, vehicle emissions, sea salt, industrial emissions and secondary aerosols, and their contributions were estimated using PMF. The crustal enrichment factors (EF) were calculated using Al as a reference for the trace metal species to identify the sources. Conditional probability functions (CPF) were computed using wind profiles and factor contributions. The results of CPF analysis were used to identify local point sources. The results suggest a competitive relationship between anthropogenic and natural source processes over the monitoring station.

In this study, long term measurements of PM2.5 and ultrafine particles (UFPs) for daily average mass concentration at Zhongshan (ZS), Sinjhuang (SJ), and Jhudong (JD) urban air monitoring stations were conducted from 2011 spring to 2013 autumn. The results showed that daily average UFPs mass concentrations in spring (average at 3 stations: 1.58 ± 0.74 µg m–3) and summer (average at 3 stations: 1.59 ± 0.53 µg m–3) were higher than those in autumn (average at 3 stations: 1.02 ± 0.28 µg m–3) and winter (average at 3 stations: 1.04 ± 0.48 µg m–3) due to the impacts by heavy traffic emission and new particle formation event. The effective density (ρeff) and dynamic shape factor (χ) for ultrafine particles (UFPs) were found to be 0.68 ± 0.16 g cm–3 and 2.06 ± 0.19, respectively, suggesting that the particle morphology was irregular shape. Based on the calculated ρeff and χ, the average number and surface area concentration ratio of UFPs to those of PM2.5 at these monitoring stations was determined to be 89.0 ± 5.5% and 42.1 ± 12.8%, respectively, suggesting that UFPs contribute significantly to the health-relevant PM2.5 aerosol fraction in these stations.