[Characteristics, Impact Factors and Potential Sources of PM Pollution for Hainan Island].

Based on the environmental monitoring data and meteorological observational data in Hainan Island from 2015 to 2021, the PM-polluted characteristics, influencing factors, and potential contributing regions were analyzed using the backward trajectory simulation, cluster analysis, potential source analysis function （PSCF）, and concentration weight trajectory （CWT） methods. The results showed that PM in Hainan Island had an obvious seasonal variation, with the highest in winter （22.6 μg·m）, followed by that in autumn and spring （17.

[Establishment and Effective Evaluation of Haikou Ozone Concentration Statistical Prediction Model].

This study selected 15 key predictors of the maximum of 8-hour averaged ozone (O) concentration (O-8h), using the O concentration of Haikou and ERA5 reanalysis data from 2015 to 2020, and constructed a multiple linear regression (MLR) model, support vector machine (SVM) model, and BP neural network (BPNN) model, to predict and test the O-8h concentration of Haikou in 2021. The results showed that the absolute value of correlation coefficients between the O-8h and related key prediction factors was mainly among 0.2 and 0.

[Spatial and Temporal Variations in Ozone Pollution and Sensitivity Characteristics in Hainan Island].

Based on ambient air quality data, meteorological observation data, and satellite remote sensing data, the temporal and spatial variations in ozone (O) pollution, the sensitivity of O, and its relationship with meteorological factors in Hainan Island were analyzed in this study. The results showed that the maximum daily 8-h moving mean (O-8h) in western and northern cities in Hainan Island was higher than that in the central, eastern, and southern cities. O-8h was the highest in 2015, and O-8h exceeding the standard proportion was the largest in 2019.

[Effects of Tropical Cyclones on Ozone Pollution in Hainan Island].

Based on the 181 tropical cyclones data in the western North Pacific Ocean from 2015 to 2020, hourly ozone (O) concentration data, and meteorological observation data of 18 cities and counties in Hainan Island, this study analyzed the impacts of tropical cyclones on ozone pollution in Hainan Island. We found that 40 (22.1%) tropical cyclones experienced O pollution in Hainan Island during the lifetime of tropical cyclones in the past six years.

[Influence of Typhoon Nangka Process on Ozone Pollution in Hainan Island].

In order to explore the influence of the 2016 typhoon Nangka on ozone (O) concentration in Hainan Island, this study employed correlation analysis and backward trajectory simulated methods, using the hourly air quality monitoring data, meteorological data, EAR5 reanalysis data, and bright temperature (TBB) infrared from the Himawari-8 satellite from October 10 to 14, 2020. The results showed that, during the typhoon process from October 11 to 13, the O-8h (maximum of 8 hours sliding average) concentration exceeded the standard. The averaged (O-8h) of Hainan Island reached its peak value (130.

[Characteristics and Potential Sources of Four Ozone Pollution Processes in Hainan Province in Autumn of 2019].

Based on the air quality and meteorological monitoring data of Hainan province in autumn of 2019, this study analyzed the characteristics and potential sources for the four O polluted processes in Hainan province, using the methods of correlation analysis, HYSPLIT backward trajectory modeling, PSCF (potential source contribution function), and CWT (concentration weighted-trajectory). The results showed that ① the average concentrations of the maximum 8h average (O-8h) for process 1 and process 3, which occurred from September 21 to 30 and November 3 to 11 with the durations of 10 d and 9 d, were 145.52 μg·m and 143.

[Temporal and Spatial Variations in Ozone and Its Causes over Hainan Province from 2015 to 2020].

This study investigated temporal and spatial variations in O-8h (defined as the maximum 8 h average result) in Hainan Province from 2015 to 2020 and further analyzed its relationships with precursors and meteorological factors based on a dataset of observations from 32 environmental monitoring stations in Hainan. Basic statistical methods, including the empirical orthogonal function (EOF), climatic tendency rate, and climatic trend coefficient analysis, were used here. The results showed that (O-8h) was higher in northern and western Hainan than that in other regions, with the maximum value occurring in Dongfang City (91.

[Temporal and spatial characteristics of atmospheric NO2 over Hainan Island and the pollutant sources in recent 10 years].

The temporal-spatial characteristics of the tropospheric column NO2 (TroNO2) and total column NO2 (TotNO2) over Hainan Island are analyzed using remote sensing data derived from OMI sensor, and also combining surface wind, SO2, HYSPLIT model to research the source of atmospheric pollutants over Hainan Island. The results show that: The value of NO2 in northern area is higher than that in southern area, and the value of NO, in central mountainous area is lower than those other places. In addition, the seasonal variation of NO2 indicates that NO2 is higher in winter and lower in summer, which can be attributed to precipitation in summer and external transport of atmospheric pollutants in winter.