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Wang J.,Institute of Urban Meteorology | Liu X.,Beijing Meteorological Observation Center | Yang X.,New South Wales Office of Environment and Heritage | Lei M.,Beijing Meteorological Information Center | And 4 more authors.
Atmospheric Environment | Year: 2014

Visibility information is fundamental in aviation, navigation, land transportation, air quality and dust storm monitoring, and military activities which often require frequent and accurate real-time observation of visibility. The traditional manual observation, the primary means to obtain visibility information by human eyes, is subjective, inconsistent and costly. Instrumental observation (or traditional optical instrument) has overcome some of these limitations, but it is difficult to obtain correct visibility information in a complicated atmospheric (e.g. rainy and foggy) environment. We developed a new visibility instrument, digital photography visiometer system (DPVS), equipped with advanced digital photographic technology including high-resolution charge-coupled-device camera and computer. The new DPVS imitates the human eye observation and accurately calculates the visibility based on its definition and observational principles. We compared the results of the new DPVS with those from a forward scattering visibility instrument (FD12) and manual visibility observations in various (rainy, non-rainy, foggy) weather conditions. The comparative results show that the new DPVS, FD12, and manual observation have the same trend of change, but the observation from the new DPVS is closer to that from the manual observations in rainy days or complicated weather conditions. Our study demonstrates that the new DVPS is superior to the optical visibility instrument and can be used for automated visibility observations under all weather conditions. © 2014 Elsevier Ltd.

Wang J.-L.,Institute of Urban Meteorology | Liu X.-L.,Beijing Meteorological Observation Center | Lei M.,Beijing Meteorological Information Center | Ruan S.-X.,Institute of Urban Meteorology | And 4 more authors.
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2014

The traditional optical visibility instruments bear their respectine in observation defects. Digital photography visiometer system (DPVS) is one new type of visibility automation observation instrument, has been developed by adophing advanced digital photography technologe and imitating manual VisibiLity observation by human ege based on the definition of visibiLity visibility's theory and according to the definition of meteorological visibility. This thesis introduced the work theory of system, compose of system, structure of hardware and software flow, in the end some contrasted experiment results between DPVS and traditional optical visibility as well as manual visibility observation were given. The results show that the three ways share the same change trend with kind of differences. And in complicated weather conditions, like rainful the differences are more obvious. ©, 2014, Chinese Institute of Electronics. All right reserved.

Wang Z.,Chinese Academy of Meteorological Sciences | Lin L.,Lanzhou University | Yang M.,Beijing Meteorological Observation Center | Xu Y.,U.S. National Center for Atmospheric Research
Climate Dynamics | Year: 2016

This study investigates the effect of reduced aerosol emissions on projected temperature and precipitation extremes in China during 2031–2050 and 2081–2100 relative to present-day conditions using the daily data output from the Community Earth System Model ensemble simulations under the Representative Concentration Pathway (RCP) 8.5 with an applied aerosol reduction and RCP8.5 with fixed 2005 aerosol emissions (RCP8.5_FixA) scenarios. The reduced aerosol emissions of RCP8.5 magnify the warming effect due to greenhouse gases (GHG) and lead to significant increases in temperature extremes, such as the maximum of daily maximum temperature (TXx), minimum of daily minimum temperature (TNn), and tropical nights (TR), and precipitation extremes, such as the maximum 5-day precipitation amount, number of heavy precipitation days, and annual total precipitation from days ˃95th percentile, in China. The projected TXx, TNn, and TR averaged over China increase by 1.2 ± 0.2 °C (4.4 ± 0.2 °C), 1.3 ± 0.2 °C (4.8 ± 0.2 °C), and 8.2 ± 1.2 (30.9 ± 1.4) days, respectively, during 2031–2050 (2081–2100) under the RCP8.5_FixA scenario, whereas the corresponding values are 1.6 ± 0.1 °C (5.3 ± 0.2 °C), 1.8 ± 0.2 °C (5.6 ± 0.2 °C), and 11.9 ± 0.9 (38.4 ± 1.0) days under the RCP8.5 scenario. Nationally averaged increases in all of those extreme precipitation indices above due to the aerosol reduction account for more than 30 % of the extreme precipitation increases under the RCP8.5 scenario. Moreover, the aerosol reduction leads to decreases in frost days and consecutive dry days averaged over China. There are great regional differences in changes of climate extremes caused by the aerosol reduction. When normalized by global mean surface temperature changes, aerosols have larger effects on temperature and precipitation extremes over China than GHG. © 2016 Springer-Verlag Berlin Heidelberg

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