Trend analysis of surface ozone at suburban Guangzhou, China.

The long-term variations of ozone are the combined results of climate change and air quality management. As Guangzhou is under the influence of both subtropical monsoon climate and rapid economic development, the ozone trend in recent years is uncertain. This paper presents the trend analysis of maximum daily average 8 h (MDA8) ozone and daily meteorological observations in Guangzhou from 2008 to 2018, using the Kolmogorov-Zurbenko (KZ) filter method.

Geographical distribution of ozone seasonality over China.

Up to now, a nation-wide scale study of surface ozone (O) concentrations in China was limited due to scarce observation. Thanks to the establishment of national air quality monitoring network in 2013, surface O data from 1402 stations during 2014-2017 were collected to investigate O seasonality. Our analysis reveals that the variations of monthly O averaged from daily mean concentration during a year show different temporal profiles depending on latitude.

Aerosol optical properties and the mixing state of black carbon at a background mountainous site in Eastern China.

In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.

[Analysis of Peroxyacetyl Nitrate and Ozone During a Typical Photochemical Pollution Process at the Panyu Atmospheric Composition Station].

The typical photochemical pollution process in Guangzhou was analyzed from 2010 to 2016 by observing photochemical pollutants (ozone (O), peroxyacetyl nitrate (PAN), volatile organic compounds (VOCs), nitrogen dioxide (NO), and nitric oxide (NO)) and meteorological factors at the Guangzhou Panyu Atmospheric Composition Station (GPACS). The results showed that during this photochemical pollution process, the average O and PAN concentrations were relatively high:O 1 h concentration was 140.6×10 and PAN 1 h concentration was 4.

Aggravating O pollution due to NO emission control in eastern China.

During the past five years, China has witnessed a rapid drop of nitrogen oxides (NO) owing to the wildly-applied rigorous emission control strategies across the country. However, ozone (O) pollution was found to steadily deteriorate in most part of eastern China, especially in developed regions such as Jing-Jin-Ji (JJJ), Yangtze River Delta region (YRD) and Pearl River Delta region (PRD). To shed more light on current O pollution and its responses to precursor emissions, we integrate satellite retrievals, ground-based measurements together with regional numerical simulation in this study.

Influence of aerosol hygroscopicity and mixing state on aerosol optical properties in the Pearl River Delta region, China.

Both the effects of aerosol hygroscopicity and mixing state on aerosol optical properties were analyzed using ground-based measurements and a Mie model in this study. The sized-resolved particle hygroscopic growth factor at RH = 90% (Gf(90%)) and the enhancement factor for the scattering coefficients (f(RH)) were measured by a self-constructed Hygroscopic Tandem Differential Mobility Analyzer (H-TDMA) and two nephelometers in parallel (PNEPs) respectively from 22nd February to 18th March 2014 in the Pearl River Delta, China. In addition, the particle number size distribution (PNSD) and BC mass concentration (M) were measured simultaneously.

Impact of typhoon periphery on high ozone and high aerosol pollution in the Pearl River Delta region.

This paper analyzes observation data in the Pearl River Delta (PRD) region from 2012 to 2013, and explores the impact of typhoon periphery on high ozone and high aerosol pollution episodes (double high episodes). Observation analysis show that severe tropical storms to severe typhoons are mainly located in the range of 10°N-30°N, 116°E-135°E when double high episodes occur. Meanwhile, obvious high temperature, low humidity, low wind speed, high actinic flux, high aerosol optical depth (AOD), and high single scattering albedo (SSA) can be observed in double high episodes.

[A Method of Aerosol Particle Number Size Distribution Inversed by PM Mass Concentration in PRD].

The aerosol particle number size distribution(PNSD) is of great importance in calculating atmospheric radiation and optics. It can effectively supplement the inadequate observation of PNSD using the widely known aerosol mass concentration (PM) measurement to invert PNSD. It would be valuable for research that needs PNSD data, like atmospheric visibility calculation.

The impact of air pollutant deposition on solar energy system efficiency: An approach to estimate PV soiling effects with the Community Multiscale Air Quality (CMAQ) model.

Deposition and accumulation of aerosol particles on photovoltaics (PV) panels, which is commonly referred to as "soiling of PV panels," impacts the performance of the PV energy system. It is desirable to estimate the soiling effect at different locations and times for modeling the PV system performance and devising cost-effective mitigation. This study presents an approach to estimate the soiling effect by utilizing particulate matter (PM) dry deposition estimates from air quality model simulations.

Transport paths and vertical exchange characteristics of haze pollution in Southern China.

Transport paths and vertical exchange characteristics are important factors for understanding the long-term transport, dispersion capability for haze prediction. Many previous studies revealed that the Pearl River Delta (PRD) region, one of the major polluted areas in China, is largely affected by the long-range pollution transport. However, mostly of these studies focused on the source apportionment or horizontal transport path of pollutants by using short-term data, and the vertical exchange characteristics had been rarely analyzed.

[Effect of VOCs on O and SOA Formation Potential During the Combined Pollution Process in Guangzhou Panyu Atmospheric Composition Station].

An analysis was made by using historical observational data of Guangzhou Panyu Atmospheric Composition Station(GPACS). The results showed that typical haze processes accompanied with high ozone episodes happened during the period from September 2rd, 2011 to September 5th, 2011(P) and the period from June 12th, 2012 to June 15th, 2012(P) respectively. During the two combined pollution processes (P and P), daily visibility ranged from 5.

Numerical simulations for the sources apportionment and control strategies of PM over Pearl River Delta, China, part I: Inventory and PM sources apportionment.

This article uses the WRF-CMAQ model to systematically study the source apportionment of PM under typical meteorological conditions in the dry season (November 2010) in the Pearl River Delta (PRD). According to the geographical location and the relative magnitude of pollutant emission, Guangdong Province is divided into eight subdomains for source apportionment study. The Brute-Force Method (BFM) method was implemented to simulate the contribution from different regions to the PM pollution in the PRD.

Numerical simulations for the sources apportionment and control strategies of PM over Pearl River Delta, China, part II: Vertical distribution and emission reduction strategies.

The contribution of various emission sources to the vertical structure of the PM concentration and the modeling of emission reduction strategies are emphasized in this study. Analysis of vertical distribution of PM concentration in the planetary boundary layer (PBL) reveals that strong diurnal cycle exists during the pollution episodes, with heavier surface pollution in nocturnal periods. Contributions from transportation and agriculture are mainly restricted to the surface, while contributions from industry and power are distributed in a relatively higher layer.

Estimation of the Land Surface Temperature over the Tibetan Plateau by Using Chinese FY-2C Geostationary Satellite Data.

During the process of land-atmosphere interaction, one of the essential parameters is the land surface temperature (LST). The LST has high temporal variability, especially in its diurnal cycle, which cannot be acquired by polar-orbiting satellites. Therefore, it is of great practical significance to retrieve LST data using geostationary satellites.

Column-integrated aerosol optical properties of coarse- and fine-mode particles over the Pearl River Delta region in China.

The sun-photometer data from 2011 to 2013 at Panyu site (Panyu) and from 2007 to 2013 at Dongguan site (Dg) in the Pearl River Delta region, were used for the retrieving of the aerosol optical depth (AOD), single scattering albedo (SSA), Ångström exponent (AE) and volume size distribution of coarse- and fine-mode particles. The coarse-mode particles presented low AOD (ranging from 0.05±0.

Diurnal variations and source apportionment of ozone at the summit of Mount Huang, a rural site in Eastern China.

Comprehensive measurements were conducted at the summit of Mount (Mt.) Huang, a rural site located in eastern China during the summer of 2011. They observed that ozone showed pronounced diurnal variations with high concentrations at night and low values during daytime.

An analysis of aerosol liquid water content and related impact factors in Pearl River Delta.

Aerosol liquid water content (ALWC) has an important effect on atmospheric visibility as well as heterogeneous chemical reactions. In this paper, we used the data size-resolved particle hygroscopic growth factor, and particle number size distribution (PNSD) obtained from H-TDMA and SMPS to compute ALWC at the Guangzhou Panyu site from the winter of 2014 and the spring of 2015. The corresponding results were relatively consistent with the trend for ALWC calculated from the ISORROPIA II thermodynamic equilibrium model based on the measurement of aerosol water-soluble ionic compositions obtained from MARGA, with a linear fit yielding an R value of 0.

Assessment of regional air quality resulting from emission control in the Pearl River Delta region, southern China.

To evaluate the impact of emission control measures on the air quality in the Pearl River Delta (PRD) region of South China, statistic data including atmospheric observations, emissions and energy consumptions during 2006-2014 were analyzed, and a Weather Research and Forecasting - Community Multi-scale Air Quality (WRF-CMAQ) model was used for various scenario simulations. Although energy consumption doubled from 2004 to 2014 and vehicle number significantly increased from 2006 to 2014, ambient SO, NO and PM were reduced by 66%, 20% and 24%, respectively, mainly due to emissions control efforts. In contrast, O increased by 19%.

Impact of relative humidity on visibility degradation during a haze event: A case study.

Light scattering of aerosols depends on ambient relative humidity (RH) since hygroscopic particles absorb significant water at high RH, and this results in low visibility. This paper used custom-made parallel nephelometers (PNEPs) to measure aerosol light scattering enhancement factor ƒ(RH), and utilized data including visibility, PM2.5, black carbon, water-soluble ions mass concentrations and surface meteorological parameters, in conjunction with background weather conditions, to analyze a haze event in Guangzhou during 8th-15th Dec.

Study on aerosol optical properties and radiative effect in cloudy weather in the Guangzhou region.

Currently, Guangzhou region was facing the problem of severe air pollution. Large amount of aerosols in the polluted air dramatically attenuated solar radiation. This study investigated the vertical optical properties of aerosols and inverted the height of boundary layer in the Guangzhou region using the lidar.

Enhanced or Weakened Western North Pacific Subtropical High under Global Warming?

The Western North Pacific Subtropical High (WNPSH) regulates East Asian climate in summer. Anomalous WNPSH causes floods, droughts and heat waves in China, Japan and Korea. The potential change of the WNPSH under global warming is concerned by Asian people, but whether the WNPSH would be enhanced or weakened remains inconclusive.

Characterization of secondary aerosol and its extinction effects on visibility over the Pearl River Delta Region, China.

Aerosol samples collected from July 2007 to March 2008 were used to obtain major aerosol constituents in an urban location in the Pearl River Delta Region (PRD), China. The minimum organic carbon (OC)/elemental carbon (EC) ratio was used to calculate the primary and secondary organic carbon and the extinction effect of the secondary aerosol on visibility was estimated. As indicated in the analysis, the mass of secondary aerosol takes up 50% of the total mass of PM2.

Chemical characterizations of soluble aerosols in southern China.

Soluble aerosols are measured at Guangdong and Hainan Provinces of southern China. The measured chemical composition of aerosols includes F-, Cl-, NO3-, SO4=, Na+, NH4+, K+, Ca2+, and Mg2+. The locations of measurements include a mega city (Guangzhou), a medium city along the coastline (Haiko), a small city along the coastline (Shanya), and a remote island site in the South China Sea (Yongxing island).