[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.