Yang J.M.,Weather Modification Office of Shanxi Province
Applied Mechanics and Materials | Year: 2014
Extreme programming and the UNIVAC computer, while unproven in theory, have not until recently been considered private. In this position paper, we argue the study of superblocks, which embodies the essential principles of artificial intelligence. We describe an algorithm for virtual modalities, demonstrating that lambda calculus and local-area networks can interact to answer this challenge. © (2014) Trans Tech Publications, Switzerland.
Hou T.,CAS Institute of Atmospheric Physics |
Lei H.,CAS Institute of Atmospheric Physics |
Lei H.,Nanjing University of Information Science and Technology |
Yang J.,CAS Institute of Atmospheric Physics |
And 2 more authors.
Atmospheric Research | Year: 2016
In this study, we investigated stratiform precipitation associated with an upper-level westerly trough and a cold front over northern China between 30 Apr. and 1 May 2009. We employed the Weather Research and Forecasting (WRF) model (version 3.4.1) to perform high-resolution numerical simulations of rainfall. We also conducted simulations with two microphysics schemes and sensitivity experiments without riming of snow and changing cloud droplet number concentrations (CDNCs) to determine the effect of snow riming on cloud structure and precipitation. Then we compared our results with CloudSat, Doppler radar and rain gauge observations. The comparison with the Doppler radar observations suggested that the WRF model was quite successful in capturing the timing and location of the stratiform precipitation region. Further comparisons with the CloudSat retrievals suggested that both microphysics schemes overestimated ice and liquid water contents. The sensitivity experiments without riming of snow suggested that the presence or absence of riming significantly influenced the precipitation distribution, but only slightly affected total accumulated precipitation. Without riming of snow, the changes of updrafts from the two microphysics schemes were different due to a different consideration of ice particle capacitance and latent heat effect of riming on deposition. While sensitivity experiments with three different CDNC values of 100, 250 and 1000 cm-3 suggested variations in snow riming rates, changing CDNC had little impact on precipitation. © 2016 Elsevier B.V.
Li J.-X.,Nanjing University of Information Science and Technology |
Yin Y.,Nanjing University of Information Science and Technology |
Li P.-R.,Weather Modification Office of Shanxi Province |
Li R.-J.,Beijing Normal University |
And 2 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014
Aircraft Measurements of aerosol spatial distribution properties in the central region of Shanxi Province were carried out in summer, 2013. The vertical distribution characteristics of aerosol number concentration and size were observed and analyzed, and the spectrum properties of aerosol particles in different height were studied. The results show that most aerosol particles were nucleation mode and accumulation mode on non-precipitation days in Shanxi Prov. in summer. Aerosol number concentration on haze day was 2 or 3 times larger than that on clear days. Aerosol number concentration decreased with altitude. A low-level aerosol accumulation zone was present due to the existence of temperature inversion layer. The mean aerosol particle size increased with height with the larger particles mainly distributed above 2500 m. The aerosol particles spectrum usually showed a bimodal or three-modal type. The width of aerosol particles spectrum broadened slightly from ground surface to 5000 m. The air mass back trajectory in observation days showed aerosol particles in high level was transported from north-west China over long distance, and aerosol particles below 3000 m mainly came from the ground emissions.
Li W.,Shandong University |
Li W.,CAS Institute of Atmospheric Physics |
Shi Z.,University of Birmingham |
Zhang D.,Prefectural University of Kumamoto |
And 5 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2012
Heavy haze frequently occurs in winter over a coal-burning region, the Taiyuan Basin, in the eastern China Loess Plateau, which is the upstream area of the North China Plain. We participated in three research flights to collect aerosol particles and to monitor SO2 concentration in hazes from the ground (780m asl) up to ∼4000m during 17-18 December, 2010. Meteorological records reveal that the whole haze column (ground to 4000m) was stable and could be further divided into three sub-layers depending on the sampling altitude, which are characterized by two shifts of the lapse rate of virtual potential temperature and water vapor mixing ratio: Layer-1, surface to 1500m; Layer-2, 1500∼3000m on 17 December, and 1500∼2500m on 18 December; Layer-3, above 3000m on 17 December and above 2500m on 18 December. SO2 concentration was 16-116ppb with an average of 58ppb in the Layer-1, 2-45ppb with an average of 10ppb in the Layer-2, and 1-10ppb with an average of 4ppb in the Layer-3. The accumulation of SO2 in the Layer-1 was due to the stable meteorological conditions and the strong anthropogenic emissions in addition to the possible valley topography. Analyses of the collected particles using a transmission electron microscope revealed the dominance of organic particles and fly ash in the Layer-1 and Layer-2 and sulfate particles in the Layer-3. The organic aerosols frequently contained certain amounts of Si and Cl. Fly ash particles consisted of O and Si with minor Fe, Mn, Zn, Ti, Pb, As, Co, and Cr. These two types of aerosol particles are typically emitted from coal burning. These results indicate that the haze particles were characterized in principle by aerosols from primary emissions of coal burning, which are different from those over the North China Plain where secondary sulfate particles are the dominant component. © 2012 American Geophysical Union. All Rights Reserved.
Zhang F.,Beijing Normal University |
Li Y.,Beijing Normal University |
Li Z.,Beijing Normal University |
Li Z.,The Interdisciplinary Center |
And 11 more authors.
Atmospheric Chemistry and Physics | Year: 2014
Aerosol hygroscopicity and cloud condensation nuclei (CCN) activity under background conditions and during pollution events are investigated during the Aerosol-CCN-Cloud Closure Experiment (AC3Exp) campaign conducted at Xianghe, China in summer 2013. A gradual increase in size-resolved activation ratio (AR) with particle diameter (Dp) suggests that aerosol particles have different hygroscopicities. During pollution events, the activation diameter (Da) measured at low supersaturation (SS) was significantly increased compared to background conditions. An increase was not observed when SS was > 0.4%. The hygroscopicity parameter (κ) was ∼ 0.31-0.38 for particles in accumulation mode under background conditions. This range in magnitude of κ was ∼ 20%, higher than κ derived under polluted conditions. For particles in nucleation or Aitken mode, κ ranged from 0.20-0.34 for background and polluted cases. Larger particles were on average more hygroscopic than smaller particles. The situation was more complex for heavy pollution particles because of the diversity in particle composition and mixing state. A non-parallel observation CCN closure test showed that uncertainties in CCN number concentration estimates ranged from 30-40%, which are associated with changes in particle composition as well as measurement uncertainties associated with bulk and size-resolved CCN methods. A case study showed that bulk CCN activation ratios increased as total condensation nuclei (CN) number concentrations (NCN) increased on background days. The background case also showed that bulk AR correlated well with the hygroscopicity parameter calculated from chemical volume fractions. On the contrary, bulk AR decreased with increasing total NCN during pollution events, but was closely related to the fraction of the total organic mass signal at m/z 44 (f44), which is usually associated with the particle's organic oxidation level. Our study highlights the importance of chemical composition in determining particle activation properties and underlines the significance of long-term observations of CCN under different atmospheric environments, especially regions with heavy pollution. © Author(s) 2014.