ALBERT

Description: [1]  The open magnetic flux ( F PC ) is a key parameter to study magnetospheric dynamical process, which is closely related to magnetic recon nections in the dayside magnetopause and magnetotail. Using global MHD simulations, we find that the open magnetic flux F PC can be estimated through a combined parameter f by F PC  = 0.89 f /( f  + 0.20) + 0.52, where the parameter is a function of the solar wind velocity ( v SW ), the solar wind number density ( n SW ), the southern interplanetary magnetic field (IMF) strength ( B S ) , and the ionospheric Pederson conductance (Σ P ). The comparison with the limited observational F PC data available in the literature shows its promising in estimating the open magnetic flux from the interplanetary and ionospheric conditions. The open magnetic flux ( F PC ) may be served as a key space weather forecast element in the future.

Description: Previous studies have reported precipitation deficits related to temperature extremes. However, how and to what extent precipitation deficits affect surface air temperatures is still poorly understood. In this study, the relationship between precipitation deficits and surface temperatures was examined in China from 1960–2012 based on monthly temperature and precipitation records from 565 stations. Significant negative correlations were identified in each season, with the strongest relationships in the summer, indicating that higher temperatures usually accompanied water-deficient conditions and lower temperatures usually accompanied wet conditions. The examination of the correlations based on 30-year moving windows suggested that the interaction between the two variables has declined over the past 3 decades. Further investigation indicated a higher impact of extreme dry conditions on temperature than that of extreme wet conditions. In addition, a new simple index (Dry and Temperature Index, DTI) was developed and used to quantitatively describe the relationship between water deficits and air temperature variations. We tested and compared the DTI in the coldest month (January) and the hottest month (July) of the year, station by station. In both months, the number of stations with a DT high I ≥ 50% was greater than those with a DT high I 〈 50%, indicating that a greater proportion of higher temperatures occurred during dry conditions. Based on the results, we conclude that water deficits in China are usually correlated to high temperatures but not to low temperatures.

Description: Using two B-spline basis functions of degree 4 and the ionospheric scintillation data from a Global Positioning Satellite System (GPS) scintillation receiver at South Pole, we reproduced ionospheric scintillation indices for the periods of the six X-class solar flares in 2013. These reproduced indices have filled the data gaps and they are serving as a smooth replica of the real observations. In either event, these modeled scintillation indices are minimizing the geometrical effects between GPS satellite and the receiver. Six X-class solar flares have been studied during the summer and winter months, using the produced scintillation indices based on the observations from the GPS receiver at South Pole and the in-situ plasma measurement from the associated passing of Defense Meteorological Satellite Program (DMSP). Our results show the solar flare peak suppresses the scintillation level and builds time-independent scintillation patterns, however, after a certain time from the solar flare peak, complicated scintillation patterns develop at high latitude ionosphere and spread towards the polar cap boundary region. Substantial consistency has been found between moderate proton fluxes and scintillation enhancement.

Description: Manufacturing of polysilicon by chemical vapor deposition from SiHCl 3 in a fluidized-bed reactor was studied. The effects of reaction temperature, H 2 /SiHCl 3 ratio, gas velocity, and seed particle loading were evaluated. The outlet gas composition was analyzed by gas chromatography. The physical features of the product particles were determined by scanning electron microscopy and laser particle size analyzer. Well-grown product particles were obtained. The temperature and H 2 /SiHCl 3 ratio significantly affected conversion, yield, and selectivity, which were less affected by gas velocity and seed particle loading at higher temperatures. The surface reaction kinetics determined the product yield only at lower temperatures, and thermodynamic equilibrium was approached at temperatures above 900 °C. The preparation of polysilicon from trichlorosilane by chemical vapor deposition was studied in a lab-scale fluidized-bed reactor. A well-grown polysilicon product was obtained. The temperature and H 2 /SiHCl 3 ratio significantly affected conversion, yield, and selectivity which were less influenced by gas velocity and seed particle loading at higher temperatures.

Description: Manufacturing of polysilicon by chemical vapor deposition from SiHCl 3 in a fluidized-bed reactor was studied. The effects of reaction temperature, H 2 /SiHCl 3 ratio, gas velocity, and seed particle loading were evaluated. The outlet gas composition was analyzed by gas chromatography. The physical features of the product particles were determined by scanning electron microscopy and laser particle size analyzer. Well-grown product particles were obtained. The temperature and H 2 /SiHCl 3 ratio significantly affected conversion, yield, and selectivity, which were less affected by gas velocity and seed particle loading at higher temperatures. The surface reaction kinetics determined the product yield only at lower temperatures, and thermodynamic equilibrium was approached at temperatures above 900 °C. The preparation of polysilicon from trichlorosilane by chemical vapor deposition was studied in a lab-scale fluidized-bed reactor. A well-grown polysilicon product was obtained. The temperature and H 2 /SiHCl 3 ratio significantly affected conversion, yield, and selectivity which were less influenced by gas velocity and seed particle loading at higher temperatures.

Description: In this survey we consider the impact of turbulence on cloud formation from the cloud scale to the droplet scale. We assess progress in understanding the effect of turbulence on the condensational and collisional growth of droplets and the effect of entrainment and mixing on the droplet spectrum. The increasing power of computers and better experimental and observational techniques allow for a much more detailed study of these processes than was hitherto possible. However, much of the research necessarily remains idealized and we argue that it is those studies which include such fundamental characteristics of clouds as droplet sedimentation and latent heating that are most relevant to clouds. Nevertheless, the large body of research over the last decade is beginning to allow tentative conclusions to be made. For example, it is unlikely that small-scale turbulent eddies (i.e. not the energy-containing eddies) alone are responsible for broadening the droplet size spectrum during the initial stage of droplet growth due to condensation. It is likely, though, that small-scale turbulence plays a significant role in the growth of droplets through collisions and coalescence. Moreover, it has been possible through detailed numerical simulations to assess the relative importance of different processes to the turbulent collision kernel and how this varies in the parameter space that is important to clouds. The focus of research on the role of turbulence in condensational and collisional growth has tended to ignore the effect of entrainment and mixing and it is arguable that they play at least as important a role in the evolution of the droplet spectrum. We consider the role of turbulence in the mixing of dry and cloudy air, methods of quantifying this mixing and the effect that it has on the droplet spectrum. Copyright © 2012 Royal Meteorological Society and British Crown Copyright, the Met Office

Description: [1]  By integrating and averaging the auroral brightness from Polar Ultraviolet Imager auroral images, which have the whole auroral ovals, and combining the observation data of interplanetary magnetic field (IMF) and solar wind from NASA Operating Missions as a Node on the Internet (OMNI), we investigate the influence of IMF and solar wind on auroral activities, and analyze the separate roles of the solar wind dynamic pressure, density, and velocity on aurora, respectively. We statistically analyze the relations between the interplanetary conditions and the auroral brightness in dawnside, dayside, duskside, and nightside. It is found that the three components of the IMF have different effects on the auroral brightness in the different regions. Different from the nightside auroral brightness, the dawnside, dayside, and duskside auroral brightness are affected by the IMF B x , and B y components more significantly. The IMF B x and B y components have different effects on these three regional auroral brightness under the opposite polarities of the IMF B z . As expected, the nightside aurora is mainly affected by the IMF B z , and under southward IMF, the larger the | B z |, the brighter the nightside aurora. The IMF B x and B y components have no visible effects. On the other hand, it is also found that the aurora is not intensified singly with the increase of the solar wind dynamic pressure: when only the dynamic pressure is high, but the solar wind velocity is not very fast, the aurora will not necessarily be intensified significantly. These results can be used to qualitatively predict the auroral activities in different regions for various interplanetary conditions.