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Search Results: 1 - 10 of 32918 matches for " GUO Xueliang "
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Distribution and origin of aerosol and its transform relationship with CCN derived from the spring multi-aircraft measurements of Beijing Cloud Experiment (BCE)
GuangXian Lu,XueLiang Guo
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-5136-9
Abstract: The atmospheric aerosol distribution, source and relationship with cloud condensation nuclei (CCN) observed during the Beijing Cloud Experiment (BCE) are analyzed. The results show that the high number concentrations of aerosol mainly distributed below 4500 m, and the magnitude could reach to 103 cm 3. Above 4500 m, the aerosol number concentrations decreased to 101 cm 3 as the altitude increases, and the aerosol mean diameters were between 0.16 and 0.19 μm. Below 4500 m, the number size distributions of aerosol showed a bimodal (multimodal) mode, and an unimodal mode above it. Due to the different sources of aerosol, the conversion ratios of aerosol to CCN were less than 20% below 4500 m, and reached 50% above the level at 0.3% supersaturation. The back trajectories showed that aerosols at higher levels above 4500 m were strongly affected by large-size particles and those below 4500 m were strongly affected by local or regional pollution. Based on observations, a relationship between the CCN number concentration and aerosol number concentration is established.
Strong Convergence of a Modified Iterative Algorithm for Mixed-Equilibrium Problems in Hilbert Spaces
Xueliang Gao,Yunrui Guo
Journal of Inequalities and Applications , 2008, DOI: 10.1155/2008/454181
Abstract: The purpose of this paper is to study the strong convergence of a modified iterative scheme to find a common element of the set of common fixed points of a finite family of nonexpansive mappings, the set of solutions of variational inequalities for a relaxed cocoercive mapping, as well as the set of solutions of a mixed-equilibrium problem. Our results extend recent results of Takahashi and Takahashi (2007), Marino and Xu (2006), Combettes and Hirstoaga (2005), Iiduka and Takahashi (2005), and many others.
Strong Convergence of a Modified Iterative Algorithm for Mixed-Equilibrium Problems in Hilbert Spaces
Gao Xueliang,Guo Yunrui
Journal of Inequalities and Applications , 2008,
Abstract: The purpose of this paper is to study the strong convergence of a modified iterative scheme to find a common element of the set of common fixed points of a finite family of nonexpansive mappings, the set of solutions of variational inequalities for a relaxed cocoercive mapping, as well as the set of solutions of a mixed-equilibrium problem. Our results extend recent results of Takahashi and Takahashi (2007), Marino and Xu (2006), Combettes and Hirstoaga (2005), Iiduka and Takahashi (2005), and many others.
A Cloud-resolving Study on the Role of Cumulus Merger in MCS with Heavy Precipitation
FU Danhong,GUO Xueliang,
FU Danhong
,GUO Xueliang

大气科学进展 , 2006,
Abstract: The cumulus merging processes in generating the mesoscale convective system (MCS) on 23 August 2001 in the Beijing region are studied by using a cloud-resolving mesoscale model of MM5. The results suggest that the merger processes occurred among isolated convective cells formed in high mountain region during southerly moving process play critical role in forming MCS and severe precipitating weather events such as hailfall, heavy rain, downburst and high-frequency lightning in the region. The formation of the MCS experiences multi-scale merging processes from single-cell scale merging to cloud cluster-scale merging, and high core merging. The merger process can apparently alter cloud dynamical and microphysical properties through enhancing both low- and middle-level forcing. Also, lightning flash rates are enhanced by the production of more intense and deeper convective cells by the merger process, especially by which, the more graupel-like ice particles are formed in clouds. The explosive convective development and the late peak lightning flash rate can be found during merging process.
Advances in weather modification from 1997 to 2007 in China

Xueliang Guo,Guoguang Zheng,

大气科学进展 , 2009,
Abstract: Rapid and significant advances in issues relevant to weather modification have been made in the last decade in China due to high water resource stresses and severe weather hazards induced by climate change. This paper reported some progress in aspects of theoretical modeling, field experiment and cloud-seeding tools, as well as research projects regarding weather modification during the ten years from 1997 to 2007. More advanced theoretical models such as cloud models with bin-microphysics and glaciogenic and hygroscopic seeding processes, and mesoscale cloud-resolving models with AgI-seeding processes have been developed to study seeding-induced changes of cloud structure and precipitation as well as to understand critical issues in association with weather modification. More advanced cloud-seeding tools such as mobile ground-based launching system of AgI-rockets and aircraft-based AgI-flares have been developed and used in operation. Several important projects aimed at exploring weather modification techniques and their applications have been conducted during this period.
TRMM-retrieved Cloud Structure and Evolution of MCSs over the Northern South China Sea and Impacts of CAPE and Vertical Wind Shear

LI Xiangshu,GUO Xueliang,FU Danhong,

大气科学进展 , 2013,
Abstract: Cloud structure and evolution of Mesoscale Convective Systems (MCSs) retrieved from the Tropical Rainfall Measuring Mission Microwave Imager (TRMM TMI) and Precipitation Radar (PR) were investigated and compared with some pioneer studies based on soundings and models over the northern South China Sea (SCS). The impacts of Convective Available Potential Energy (CAPE) and environmental vertical wind shear on MCSs were also explored. The main features of MCSs over the SCS were captured well by both TRMM PR and TMI. However, the PR-retrieved surface rainfall in May was less than that in June, and the reverse for TMI. TRMM-retrieved rainfall amounts were generally consistent with those estimated from sounding and models. However, rainfall amounts from sounding-based and PR-based estimates were relatively higher than those retrieved from TRMM-TMI data. The Weather Research and Forecasting (WRF) modeling simulation underestimated the maximum rain rate by 22% compared to that derived from TRMM-PR, and underestimated mean rainfall by 10.4% compared to the TRMM-TMI estimate, and by 12.5% compared to the sounding-based estimate. The warm microphysical processes modeled from both the WRF and the Goddard Cumulus Ensemble (GCE) models were quite close to those based on TMI, but the ice water contents in the models were relatively less compared to that derived from TMI. The CAPE and wind shear induced by the monsoon circulation were found to play critical roles in maintaining and developing the intense convective clouds over SCS. The latent heating rate increased more than twofold during the monsoon period and provided favorable conditions for the upward transportation of energy from the ocean, giving rise to the possibility of inducing large-scale interactions.
Climatic Features of Cloud Water Distribution and Cycle over China
LI Xingyu,GUO Xueliang,ZHU Jiang,
LI Xingyu
,GUO Xueliang,ZHU Jiang

大气科学进展 , 2008,
Abstract: Analyses of cloud water path(CWP)data over China available from the International Satellite Cloud Climatology Project(ISCCP)are performed for the period 1984-2004.Combined with GPCP precipitation data,cloud water cycle index(CWCI)is also calculated.The climatic distributions of CWP are found to be dependent on large-scale circulation,topographical features,water vapor transport and similar distribution features which are found in CWCI except in the Sichuan Basin.Influenced by the Asia monsoon,CWP over China exhibits very large seasonal variations in different regions.The seasonal cycles of CWCI in different regions are consistent and the largest CWCI occurs in July.The long-term trends of CWP and CWCI are investigated,too.Increasing trends of CWP are found during the period with the largest increase found in winter.The decreasing trends of CWCI dominate most regions of China.The differences in long-term trends between CWP and CWCI suggest that CWP only can influence the variation of CWCI to a certain extent and that other factors need to be involved in cloud water cycle researches.This phenomenon reveals the complexity of the hydrological cycle related to cloud water.
MUC5AC Upstream Complex Repetitive Region Length Polymorphisms Are Associated with Susceptibility and Clinical Stage of Gastric Cancer
Chenghua Wang, Jinshen Wang, Yiqing Liu, Xueliang Guo, Chunqing Zhang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098327
Abstract: MUC5AC was deemed to be involved in gastric carcinogenesis since aberrant MUC5AC expression has been repeatedly detected in patients with gastric cancer (GC). In this study, length polymorphisms in a complicated repetitive region adjacent to MUC5AC promoter were assessed in 230 patients with GC and 328 cancer-free controls. Alleles of 1.4 and 1.8 kb were significantly more prevalent in GC group than in controls. In contrast, 2.3 and 2.8 kb alleles occurred at significantly lower frequencies in patients than in controls. Alleles were then classified into susceptible (S; 1.4 and 1.8 kb), protective (P; 2.3 and 2.8 kb) and null (N; all other alleles) categories with respect to their linkage with the susceptibility to GC. Individuals with genotype SS had a 2.7-fold increased risk of GC occurrence, but PN genotype was associated with a significantly reduced risk of this cancer. Moreover, homozygous or heterozygous individuals with one or two copies of 1.4 kb allele showed an earlier age of onset and more advanced metastasis stage compared with patients without this allele (Bonferroni corrected p = 1.35×10?4 and 6.60×10?4 accordingly), whereas homozygous patients with two copies of 1.8 kb allele were linked to less advanced GC TNM stage. Our results suggest that certain genetic variations in MUC5AC upstream repetitive region are associated with the susceptibility and progression of GC.
人为大气污染物对一次冬季浓雾形成发展的影响研究
贾星灿 JIA Xingcan,郭学良 GUO Xueliang
大气科学 , 2012, DOI: 10.3878/j.issn.1006-9895.2012.11200
Abstract: 基于WRF/Chem模式和雾的观测资料,开展了包含和不包含人为污染排放源两种大气背景条件下的数值模拟对比试验,在此基础上探讨了人为污染物对2009年12月1日发生在我国华北和华东地区的一次浓雾天气过程的影响机理.结果表明,在考虑污染排放源时,模式模拟的雾的空间分布和强度变化与卫星、能见度仪和微波辐射计的观测更为接近.污染条件下的边界层结构更有利于雾的形成,人为大气污染物使雾的范围最大增加50%,雾的强度最大增加5倍,平均延长雾持续时间1.5小时.由于人为污染物增加了雾凝结核(FCN)数浓度,进而使雾滴数浓度显著增大,有利于雾的增强.同时,污染物通过影响雾滴的凝结过程和潜热释放过程,对长波辐射降温和湍流过程有重要影响,使边界层的热力和动力结构更有利于雾的增强和发展.污染气体SO2、NOx和NH3的排放产生的二次气溶胶对雾的形成和发展具有重要影响.不考虑这些污染气体排放时,平均雾水含量可降低32%.
强雷暴云中电荷多层分布与形成过程的三维数值模拟研究
周志敏 ZHOU Zhimin,郭学良 GUO Xueliang
大气科学 , 2009, DOI: 10.3878/j.issn.1006-9895.2009.03.17
Abstract: 通过建立云物理耦合电过程的冰粒子分档模式,对北京一次强雷暴天气的云中空间电荷结构分布、形成机制及放电过程进行了模拟分析研究。结果表明:(1)云水含量主要通过感应起电来影响云水、霰粒子之间的电荷转移,然后再影响空间电荷分布。而包含了雨水后的液水含量主要通过非感应起电在不同含水量条件下的起电机制影响霰粒子同雪粒子(或冰晶)碰撞后转移电荷的极性与大小,从而影响空间电荷结构。(2)微物理过程的不均匀性将导致水成物含水量源汇项的不均匀性。而这种不均匀性首先会使得水成物在不同垂直剖面上的分布也不均匀,从而使得感应、非感应起电变得更复杂。源汇项的不均匀性还会导致水成物之间因质量转移而产生的电荷转移也不均匀。(3)强的上升气流将冰相物携带到较高处,从而使得水成物间发生电荷转移的高度也比较高。雪粒子在强上升气流上部及两侧区域出现多个含量中心,霰粒子含量分布相对均匀,而质量中心向背风侧倾斜。因此,非感应起电过程主要发生在背风侧的辐散区域,从而导致空间电荷也主要分布在该区域。强上升气流使得冰相水成物在不同区域出现含量中心,使得同一冰相物在不同区域携带不同电荷(尤其是在强风暴的成熟期),从而使得空间电荷易于出现多层结构。(4)由于放电会改变空间电荷结构,放电通道中的感应电荷会重新分配到各个水成物表面,所以在微物理过程和动力过程等作用下,在水成物质量转移过程中发生的电荷转移将会更加复杂,从而使得空间电荷浓度分布更加复杂。但是该作用的重要性还需要进一步的研究。以上因子均是造成空间电荷多层分布的重要原因。
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