[1] Aerosol vertical distribution is an important piece of information to improve aerosol retrieval from satellite remote sensing. Aerosol extinction coefficient profile and its integral form, aerosol optical depth (AOD), as well as atmospheric boundary layer (ABL) height and haze layer height can be derived using lidar measurements. In this paper, we used micropulse lidar measurements acquired from May 2003 to June 2004 to illustrate seasonal variations of AOD and ABL height in Hong Kong. On average, about 64% of monthly mean aerosol optical depths were contributed by aerosols within the mixing layer (with a maximum ($76%) in November and a minimum ($55%) in September) revealing the existence of large abundance of aerosols above ABL due to regional transport. The characteristics of seasonal averaged aerosol profiles over Hong Kong in the study period are presented to illustrate seasonal phenomena of aerosol transport and associated meteorological conditions. The correlation between AOD and surface extinction coefficient, as found, is generally poor (r 2 $0.42) since elevated aerosol layers increase columnar aerosol abundance but not extinction at surface. The typical aerosol extinction profile in the ABL can be characterized by a low value near the surface and values increased with altitude reaching the top of ABL. When aerosol vertical profile is assumed, surface extinction coefficient can be derived from AOD using two algorithms, which are discussed in detail in this paper. Preliminary analysis showed that better estimates of the extinction coefficient at the ground level could be obtained using two-layer aerosol extinction profiles (r 2 $0.78, slope $0.82, and intercept $0.15) than uniform profiles of extinction with height within the ABL (r 2 $0.65, slope $0.27, and intercept $0.03). The improvement in correlation is promising on mapping satellite retrieved AOD to surface aerosol extinction coefficient for urban and regional environmental studies on air quality related issues.Citation: He, Q

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[1] Height-resolved data of the particle optical properties, the vertical extend of the haze layer, aerosol stratification, and the diurnal cycle of vertical mixing over the Pearl River Delta in southern China are presented. The observations were performed with Raman lidar and Sun photometer at Xinken (22.6°N, 113.6°E) near the south coast of China throughout October 2004. The lidar run almost full time on 21 days. Sun photometer data were taken on 23 days, from about 0800 to 1700 local time. The particle optical depth (at about 533-nm wavelength) ranged from 0.3-1.7 and was, on average, 0.92. Å ngström exponents varied from 0.65 -1.35 (for wavelengths 380 to 502 nm) and from 0.75 -1.6 (for 502 to 1044 nm), mean values were 0.97 and 1.22. The haze -layer mean extinction -to -backscatter ratio ranged from 35-59 sr, and was, on average, 46.7 sr. The top of the haze layer reached to heights of 1.5-3 km in most cases. Citation: Ansmann, A., R. Engelmann,

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BackgroundHand, foot, and mouth disease (HFMD) has become an emerging infectious disease in China in the last decade. There has been evidence that meteorological factors can influence the HFMD incidence, and understanding the mechanisms can help prevent and control HFMD.MethodsHFMD incidence data and meteorological data in Minhang District, Shanghai were obtained for the period between 2009 and 2015. Distributed lag non-linear models (DLNMs) were utilized to investigate the impact of meteorological factors on HFMD incidence after adjusting for potential confounders of long time trend, weekdays and holidays.ResultsThere was a non-linear relationship between temperature and HFMD incidence, the RR of 5th percentile compared to the median is 0.836 (95% CI: 0.671–1.042) and the RR of 95th percentile is 2.225 (95% CI: 1.774–2.792), and the effect of temperature varied across age groups. HFMD incidence increased with increasing average relative humidity (%) (RR = 1.009, 95% CI: 1.005–1.015) and wind speed (m/s) (RR = 1.197, 95% CI: 1.118–1.282), and with decreasing daily rainfall (mm) (RR = 0.992, 95% CI: 0.987–0.997) and sunshine hours (h) (RR = 0.966, 95% CI: 0.951–0.980).ConclusionsThere were significant relationships between meteorological factors and childhood HFMD incidence in Minhang District, Shanghai. This information can help local health agencies develop strategies for the control and prevention of HFMD under specific climatic conditions.Electronic supplementary materialThe online version of this article (10.1186/s40249-018-0388-5) contains supplementary material, which is available to authorized users.

Abstract. The aerosol extinction-to-backscatter ratio is an important parameter for inverting LIDAR signals in the LI-DAR equation. It is a complicated function of the aerosol microphysical characteristics. In this paper, a method to retrieve the column-averaged aerosol extinction-to-backscatter ratio by constraining the aerosol optical depths (AOD) from a Micro-pulse LIDAR (MPL) by the AOD measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. Both measurements were taken on cloud free days between 1 May 2003 and 30 June 2004 over Hong Kong, a coastal city in south China. Simultaneous measurements of aerosol scattering coefficients with a forward scattering visibility sensor are compared with the LI-DAR retrieval of aerosol extinction coefficients. The data are then analyzed to determine seasonal trends of the aetrosol extinction-to-backscatter ratio. In addition, the relationships between the extinction-to-backscatter ratio and wind conditions as well as other aerosol microphysical parameters are presented. The mean aerosol extinction-to-backscatter ratio for the whole period was found to be 29.1±5.8 sr, with a minimum of 18 sr in July 2003 and a maximum of 44 sr in March 2004. The ratio is lower in summer because of the dominance of oceanic aerosols in association with the prevailing southwesterly monsoon. In contrast, relatively larger ratios are noted in spring and winter because of the increased impact of local and regional industrial pollutants associated with the northerly monsoon. The extended LIDAR measurements over Hong Kong provide not only a more accurate retrieval of aerosol extinction coefficient profiles, but also significant substantial information for air pollution and climate studies in the region.

[1] Using a CIMEL Sun photometer, we conducted continuous observations over the urban area of Shanghai (31 14′N, 121 32′E) from 18 April 2007 to 31 January 2009. The aerosol optical depth (AOD), Angstrom wavelength exponent, single scattering albedo (w 0 ), and aerosol particle size distribution were derived from the observational data. The monthly mean AOD reached a maximum value of 1.20 in June and a minimum value of 0.43 in January. The monthly averaged Angstrom wavelength exponent reached a minimum value of 1.15 in April and a maximum value of 1.41 in October. The frequencies of the AOD and Angstrom wavelength exponent presented lognormal distributions. The averaged w 0 at 550 nm was 0.94 throughout the observation period, indicating that the aerosols over Shanghai are composed mainly of scattering particles. The concentrations of coarse mode and accumulation mode aerosols over Shanghai were highest in spring compared with other seasons, especially for those particles with radii between 1.0 and 2.0 mm. The median radius of monthly averaged accumulation mode aerosols increased with increasing AOD, and fine particles accounted for the majority of the aerosol volume concentration. The ratios of the monthly averaged volume concentration of accumulation mode and coarse mode aerosols (V f /V c ) were over 0.6 for all months studied and reached up to 1.94 in August. The volumes of the two modes changed with AOD, but their correlations presented different sensitivities, that is, the volume concentration of accumulation mode aerosols was more sensitive to variations in AOD than that of coarse mode aerosols. The aerosol volume concentration decreased with increasing w 0 , indicating that the higher the volume concentration of aerosols, the higher the absorption in particle extinction properties. The increase in absorption was caused primarily by secondary species coated on black carbon (BC) and primary organic carbon (POC) particles.Citation: He, Q

East China is among the fastest developing area in Asia, where atmospheric aerosol loading is high due to heavy urban and industrial emission. The Moderate Resolution Imaging Spectroradiometer (MODIS) level 2 aerosol products (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) were used to study aerosol spatial and temporal distributions, as well as their variations with local meteorological conditions over East China. By combining Aerosol Optical Depth (AOD) and aerosol Fine Mode Fraction (FMF), we found that the urban/industrial aerosol and soil dust are possibly two dominant species over northern part, whereas continental and marine aerosols possibly dominate the southern part of East China. Both annual mean AOD and area with high AOD increased from 2000 to 2007, with the largest increase seen in Yangtze River Delta region (YRD). In summer, AOD in East China reached the maximum of about 0.8 in YRD, dominated by fine mode particles. The minimum AOD occurred in winter with mostly coarse mode particles. Local aerosol properties were analyzed in three typical zones: the northern dry zone (I), the central urban/industrial zone (II) and the southern natural background zone (III). Monthly mean AODs in zone I and II were above 0.5 throughout the entire year, with the maximum AOD in June. High FMFs in this period indicated heavy urban and industrial pollution. Monthly mean AODs and FMFs in zone III reached maximum of 0.51 in April and September (up to 90.7%) respectively. High AOD in spring in zone III appears mostly due to the long-range dust transport from the North.