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Sun Z.,Research and Development Branch | Li J.,Environment Canada | He Y.,Nanjing University of Information Science and Technology | Liu A.,Tianjin Institute of Meteorology | And 2 more authors.
AIP Conference Proceedings | Year: 2017

An issue in the determination of the direct component of solar radiation involving the circumsolar contribution in numerical weather prediction and climate models is discussed. The direct flux determined using the delta-Eddington approximation is assessed against observations. The results show that errors due to the use of the delta-scaling are much larger than errors if the circumsolar contribution is ignored. In order to include the scattering contribution in the direct flux calculation properly, a simple parameterization for dust aerosol is developed which can be used to consider the scattering contribution due to the particular case of dust aerosol to the direct solar radiation within the circumsolar region. © 2017 Author(s).

Lu X.,Tianjin Academy of Environmental science | Han M.,Tianjin Academy of Environmental science | Ran L.,Peking University | Han S.,Tianjin Institute of Meteorology | Zhao C.,Peking University
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2011

Because of the importance of nonmethane organic compounds (NMOC) as one of precursors of tropospheric ozone, measuring the composition and ozone formation potentials of various NMOCs species will help us better understand the urban ozone formation mechanism. NMOCs sampling was conducted at an interval of 2~3 hours from 7: 30 am~23: 00 pm (five times per day) from 6 to 13 August, 2010 at the Tianjin Meteorology Bureau Tower in downtown Tianjin. The mean concentration of daily NMOCs is 342 ppbC and the major components are alkanes and aromatics. According to assessment using both a OH-reactivity-based method (propene-equivalent concentration) and maximum incremental reactivity, aromatics play a dominant role in contributing to photochemical ozone production. Despite having the lowest mixing ratio, alkenes are next to aromatics in their contribution to ozone formation. Butene, xylene and trimethylbenzene are among the top compounds in terms of their ozone formation potentials. Compared to urban Shanghai, both the mean concentration and concentration range of NMOCs in downtown Tianjin were much greater within the sampling period.

Han M.,Tianjin Academy of Environmental science | Han M.,State Environmental Protection Key Laboratory of Odor Pollution Control | Lu X.,Tianjin Academy of Environmental science | Zhao C.,Peking University | And 3 more authors.
Advances in Atmospheric Sciences | Year: 2015

Tianjin is the third largest megacity and the fastest growth area in China, and consequently faces the problems of surface ozone and haze episodes. This study measures and characterizes volatile organic compounds (VOCs), which are ozone precursors, to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin, China during the HaChi (Haze in China) summer campaign in 2009. A total of 107 species of ambient VOCs were detected, and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv, respectively. Of those, 51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization. The identified sources of VOCs were significantly related to vehicular activities, which specifically contributed 60% to urban and 42% to suburban VOCs loadings in Tianjin. Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas, although the contribution of industry in the suburban area (36%) was much higher than that at the urban area (16%). We conclude that controlling vehicle emissions should be a top priority for VOC reduction, and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life, especially in suburban areas. © 2015, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

Guan F.,Hebei Provincial Meteorological and Eco environmental Key Laboratory | Zheng Y.,Nanjing University of Information Science and Technology | Cai Z.,Tianjin Institute of Meteorology | Yu C.,Hebei Provincial Meteorological and Eco environmental Key Laboratory | Zhang N.,Hebei Provincial Meteorological and Eco environmental Key Laboratory
Acta Meteorologica Sinica | Year: 2011

Solar radiation is an important energy source for plants on the earth and also a major component of the global energy balance. Variations in solar radiation incident at the earth's surface profoundly affect the human and terrestrial environment, including the climate change. To provide useful information for predicting the future climate change in China, distinctive regional features in spatial and temporal variations of the surface solar radiation (SSR) and corresponding attributions (such as cloud and aerosol) are analyzed based on SSR observations and other meteorological measurements in North and East China from 1961 to 2007. Multiple models, such as the plane-parallel radiative transfer model, empirical and statistical models, and correlation and regression analysis methods are used in the study. The results are given as follows. (1) During 1961-2007, the total SSR in North China went through a process from quickly "dimming to slowly "dimming, while in East China, a significant transition from "dimming to "brightening occurred. Although there are some differences between the two regional variation trends, long-term variations in SSR in the two regions are basically consistent with the observation worldwide. (2) Between the 1960s and 1980s, in both North and East China, aerosols played a critical role in the radiation dimming. However, after 1989, different variation trends of SSR occurred in North and East China, indicating that aerosols were not the dominant factor. (3) Cloud cover contributed less to the variation of SSR in North China, but was the major attribution in East China and played a promoting role in the reversal of SSR from dimming to brightening, especially in the "remarkable brightening" period, with its contribution as high as 70%. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2011.

Sun Z.,Center for Australian Weather and Climate Research | Liu A.,Tianjin Institute of Meteorology
Solar Energy | Year: 2013

A fast scheme for estimation of the instantaneous direct solar irradiance (DSI) at the Earth's surface is developed based on detailed radiative transfer calculations for the full range of atmospheric conditions. The parameterisation is divided into the components for clear sky and overcast conditions. For the clear sky condition, the effects of absorption due to water vapour, carbon dioxide and ozone on the DSI are explicitly treated. The effects of Rayleigh scattering, aerosols are also treated on a physical basis. Based on the clear sky results, the transmittances due to effects of clouds are determined for both liquid and ice clouds. The results are parameterised in terms of cloud visible optical depth. The input variables required for determination of DSI include precipitable water, column ozone amount, CO2 mixing ratio, aerosol optical depth, cloud visible optical depth, surface pressure and solar zenith angle. These variables are all available in numerical weather prediction (NWP) forecast models or can be obtained from satellite observations. Therefore, the scheme can be used to determine the DSI using NWP model products or satellite data.The scheme has been tested using the observations obtained at three stations of the US Department of Energy Atmospheric Radiation Measurements (ARM) program. The relative mean bias differences under clear-sky and all-sky conditions are better than 3.2% and 5.1%, respectively. The correlation coefficients between modelled results and observations are all greater than 0.99.The sampling errors of DSI due to the use of 3-hourly or 1-hourly low frequency in radiation calculations in NWP models are evaluated using the fast scheme and ARM observational data. It is found that these errors can be greater than 800Wm-2 for many cases where sky condition changes from clear to overcast. Application of the current scheme can reduce these errors to less than 100Wm-2. © 2012 Elsevier Ltd.

Li M.-c.,Tianjin Climate Center | Xiong M.-m.,Tianjin Climate Center | Huang H.,Tianjin Institute of Meteorology | Ren Y.,Tianjin Climate Center | Zhang H.,Tianjin Institute of Meteorology
Chinese Journal of Ecology | Year: 2012

In order to understand the potential effects of urban planning on local climate, the Nangang industrial area in the south Binhai New Area of Tianjin was taken as a case, and a boundary layer model was applied to simulate the variations of climatic environmental elements before and after urban planning, with the possible effects on the petrochemical industry in this area analyzed. The results showed that urban planning had obvious effects on the air temperature in all four seasons. After the planning, the air temperature in spring mostly showed decrease, with the largest decrement of 0.6 °C at 1:00 pm, and the air temperature in winter, summer, and autumn showed a pattern of apparent decrease at daytime and the largest increase at night. The variation range of the air temperature was larger in winter than in summer and autumn. Urban planning had obvious effects on the enhancement of wind speed in winter, spring, and autumn, with the amplitude of 0.6 m·s-1, 0.4 m·s-1, and 0.6 m·s-1, respectively. The wind speed in summer after urban planning only had a weak enhancement (0.2 m·s-1). The variation of air temperature and the enhancement of wind speed would benefit the petrochemical industry in this area, because the temperature decrease at daytime, especially in summer, would increase the human comfort and reduce the risks of petrochemical industry, and the enhancement of wind speed would be favorable to the diffusion of pollutants. Overall, urban planning made the local climatic environmental elements have a great change, which would be beneficial to the production of petrochemical industry.

Cai Z.-Y.,Tianjin Institute of Meteorology | Han S.-Q.,Tianjin Institute of Meteorology | Huang H.,Tianjin Institute of Meteorology | Yao Q.,Tianjin Institute of Meteorology
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2011

Based on the observational gradient date of black carbon aerosol (BC), pollutants, and meteorological data at Tianjin boundary layer station from August 12 to September 18, 2010, characteristics and influencing factors of BC concentration variation were analyzed. The average concentration of BC was 6.309mg/L and its mass percentage in PM10 was 4.17%.The absorption of BC accounted for 10.23% of total aerosol extinction. Influenced by human activity and boundary layer structure, the diurnal variation of BC showed two peaks, peaked at 7:00, lowest during 14:00~16:00, and the second peak at 20:00. BC concentration decreased with wind speed increasing. The BC concentration was generally lower than 5 mg/L when the wind speed higher than 4m/s. West and northwest wind had obvious transportation effect on BC in Tianjin city. The probability of high BC events with the concentration greater than 10mg/L was 18.07%. Inversion and atmospheric stability could lead to BC accumulate in the near surface layer and form high pollution events.

Meng L.-H.,Tianjin Institute of Meteorology | Zhang M.,Tianjin Institute of Meteorology | Han S.-Q.,Tianjin Institute of Meteorology
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2012

Based on the observation data that have been obtained, the vertically characteristic of wind field and temperature field in winter of Tianjin city have been studied. The results showed that, during the testing time, the direction of wind as the height increased a clockwise rotation, by East, Southeast gradually turn right, turn to the southwest wind, west wind, following the Eckman spiral pattern; different height level wind changed in the appearance of different laws daily. In general, at low height the wind speed was bigger at the day than the night, but at the more height was contrast; the grounding inverse temperature generated about 20:00. With increasing of the time the inverse temperature enhanced, and on the 02:00 of the second day, the inverse temperature were the most; the height of the mixed boundary was thinner in the early morning, thicker in the afternoon, which was beneficial to the spread of pollutants. The daily variation of the wind speed were the same between the urban and the suburban of the same height at 10 m and 100 m; but it was different at the 200 m; the urban wind speed fluctuation was smaller than the suburb with time daily.

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