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Search Results: 1 - 10 of 43893 matches for " WU Tongwen "
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An Empirical Formula to Compute Snow Cover Fraction in GCMs
WU Tongwen,WU Guoxiong,
WU Tongwen
,WU Guoxiong

大气科学进展 , 2004,
Abstract: There exists great uncertainty in parameterizing snow cover fraction in most general circulation models (GCMs) using various empirical formulae, which has great influence on the performance of GCMs.This work reviews the commonly used relationships between region-averaged snow depth (or snow water equivalent) and snow cover extent (or fraction) and suggests a new empirical formula to compute snow cover fraction, which only depends on the domain-averaged snow depth, for GCMs with different horizontal resolution. The new empirical formula is deduced based on the 10-yr (1978-1987) 0.5°× 0.5° weekly snow depth data of the scanning multichannel microwave radiometer (SMMR) driven from the Nimbus-7Satellite. Its validation to estimate snow cover for various GCM resolutions was tested using the climatology of NOAA satellite-observed snow cover.
Simulation of Asian Monsoon Seasonal Variations with Climate Model R42L9/LASG
Simulation of Asian Monsoon Seasonal Variations with Climate Model R42L9/LASG

WANG Zaizhi,WU Guoxiong,WU Tongwen,YU Rucong,
WANG Zaizhi
,WU Guoxiong,WU Tongwen,YU Rucong

大气科学进展 , 2004,
Abstract: The seasonal variations of the Asian monsoon were explored by applying the atmospheric general circulation model R42L9 that was developed recently at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences (LASG/IAP/CAS). The 20-yr (1979-1998) simulation was done using the prescribed20-yr monthly SST and sea-ice data as required by Atmospheric Model Intercomparison Project (AMIP)Ⅱ in the model. The monthly precipitation and monsoon circulations were analyzed and compared with the observations to validate the model's performance in simulating the climatological mean and seasonal variations of the Asian monsoon. The results show that the model can capture the main features of the spatial distribution and the temporal evolution of precipitation in the Indian and East Asian monsoon areas. The model also reproduced the basic patterns of monsoon circulation. However, some biases exist in this model. The simulation of the heating over the Tibetan Plateau in summer was too strong. The overestimated heating caused a stronger East Asian monsoon and a weaker Indian monsoon than the observations. In the circulation fields, the South Asia high was stronger and located over the Tibetan Plateau. The western Pacific subtropical high was extended westward, which is in accordance with the observational results when the heating over the Tibetan Plateau is stronger. Consequently, the simulated rainfall around this area and in northwest China was heavier than in observations, but in the Indian monsoon area and west Pacific the rainfall was somewhat deficient.
Hybrid Anion Exchange Hollow Fiber Membrane for Delivery of Ionic Drugs
Na Wang,Mengbing Cui,Cuiming Wu,Yiyun Cheng,Tongwen Xu
International Journal of Chemical Engineering , 2012, DOI: 10.1155/2012/832190
Abstract: Hybrid anion exchange hollow fiber membranes (HAEHFMs) based on bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) are proposed as potential drug carriers for four anionic model drugs, including the sodium salts of benzoate (NaBS), salicylate (NaSA), meta-amino salicylate (NaMAS), and loxoprofen (NaLS). The results of the static loading and release experiments suggest that electrostatic interaction, hydrogen bonding, and hydrophobic interaction are the main interaction patterns between the membrane and the drugs. And they are directly influenced by the external phase conditions and the drug physicochemical characteristics, such as structure, molecular weight, dissociation (pKa), and hydrogen bonding capability. Among the four different drugs, NaSA and NaMAS appear to be the most suitable for controlled release by the HAEHFM due to their excellent adsorption/release behaviors. 1. Introduction Controlled drug release has attracted increasing attention during recent decades because of its special advantages on providing a relatively steady blood level of drug, optimizing the drug therapeutics and improving patient compliance. The most significant pursuit of developing controlled release system is to prolong the retention of the drug and get a constancy of release rate. Membranes have been evaluated as one of the most promising drug delivery vehicles [1, 2]. In order to develop rate-limiting drug delivery membrane, ion transport and ion exchange mechanisms can be introduced through the use of ion exchange membranes (IEMs). The ion exchange groups of the IEMs can capture the ionized drugs through electrostatic interactions and thus provide a permselectivity for the therapeutic agents in the drug delivery profiles [3]. Up to date, many types of IEMs have been used directly or modified as drug vehicles such as Nafion [4], modified chitosan [1, 5–7], polypyrrole [8], poly(acrylic acid) grafted poly(vinylidene fluoride) (PAA-PVDF) [9, 10], and bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide) (BPPO) membranes [11]. The rate-limiting performance of the IEMs for ionic drugs mainly depends on the physical and chemical properties of the IEMs and the drugs, as well as the external solution conditions [12]. IEMs can be classified into ion exchange flat membranes and ion exchange hollow fiber membranes (IEHFMs) according to the physical configuration. IEHFMs, as a novel type of drug delivery vehicles, have been proved to be effective in rate-limiting drug release. Our research group has previously promoted a novel type of hybrid anion exchange hollow
全球大气环流模式BCC_AGCM2.0.1对1998年夏季江淮流域强降水过程的回报试验研究
颉卫华 JIE Weihua,吴统文 WU Tongwen
大气科学 , 2010, DOI: 10.3878/j.issn.1006-9895.2010.05.11
Abstract: 利用中国气象局北京气候中心全球大气环流模式(BCC_AGCM2.0.1)对1998年6月24日~7月3日发生在我国江淮流域的强降水天气过程进行了回报试验。模式起报时间为1998年6月24日00时,使用前10天NCEP-II再分析逐时温度、涡度和散度场进行预报前初始协调(spin-up)积分,产生模式初值,预报时段为1998年6月24日~7月10日,回报试验结果表明:模式对全球500hPa位势高度的天气尺度演变过程具有4~7天的可预报性;BCC_AGCM2.0.1模式对中国区域的降水以及大气环流场具有3~4天的可预报性,6月24日起报后3天内的预报降水区域位置与实况一致,但中心强度有所差异。对起报后未来2天的5mm和10mm以上的降水预报能力相对较强,ETS评分值达到了0.25以上,HK评分超过了0.4,降水区域范围预报较为准确,BIA评分趋于1.0。模式对20mm以上的降水也具有一定的可预报性,但模式对大于30mm以上强降水的预报能力较差。
The Performance of Atmospheric Component Model R42L9 of GOALS/LASG
The Performance of Atmospheric Component Model R42L9 of GOALS/LASG

WU Tongwen,LIU Ping,WANG Zaizhi,LIU Yimin,YU Rucong,WU Guoxiong,
WU Tongwen
,LIU Ping,WANG Zaizhi,LIU Yimin,YU Rucong,WU Guoxiong

大气科学进展 , 2003,
Abstract: This paper examines the performance of an atmospheric general circulation model (AGCM) de-veloped at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysi-cal Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated atR42(2.8125°long× 1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG here-after. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatologicalmonthly mean sea surface temperature is compared with the 40-year (1958 97) U.S. National Centerfor Environmental Prediction (NCEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthlyprecipitation clinatology. The mean DJF and JJA geographical distributions of precipitation, sea levelpressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for thelast 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well theobserved basic patterns, particularly precipitation over the East Asian region. Comparing the new modelwith R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obviousinprovement in the simulation of regional climate, especially precipitation. The weaknesses in simulationand future improvements of the model are also discussed.
An Evaluation of the Effects of Cloud Parameterization in the R42L9 GCM
An Evaluation of the Efiects of Cloud Parameterization in the R42L9 GCM

WU Tongwen,WANG Zaizhi,LIU Yimin,YU Rucong,WU Guoxiong,
WU Tongwen
,WANG Zaizhi,LIU Yimin,YU Rucong,WU Guoxiong

大气科学进展 , 2004,
Abstract: Cloud is one of the uncertainty factors influencing the performance of a general circulation model (GCM). Recently, the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics (LASG/IAP) has developed a new version of a GCM (R42L9). In this work, roles of cloud parameterization in the R42L9 are evaluated through a comparison between two 20year simulations using different cloud schemes. One scheme is that the cloud in the model is diagnosed from relative humidity and vertical velocity, and the other one is that diagnostic cloud is replaced by retrieved cloud amount from the International Satellite Cloud Climatology Project (ISCCP), combined with the amounts of high-, middle-, and low-cloud and heights of the cloud base and top from the NCEP. The boreal winter and summer seasonal means, as well as the annual mean, of the simulated top-of-atmosphere shortwave radiative flux, surface energy fluxes, and precipitation are analyzed in comparison with the observational estimates and NCEP reanalysis data. The results show that the scheme of diagnostic cloud parameterization greatly contributes to model biases of radiative budget and precipitation. When our derived cloud fractions are used to replace the diagnostic cloud amount, the top-of-atmosphere and surface radiation fields are better estimated as well as the spatial pattern of precipitation. The simulations of the regional precipitation, especially over the equatorial Indian Ocean in winter and the Asia-western Pacific region in summer, are obviously improved.
Feature of Mean Vertical Circulation over the Qinghai-Xizang Plateau and Its Neighborhood
青藏高原及周围地区的平均垂直环流特征

Qian Zheng''an,Wu Tongwen,Liang Xiaoyun,
钱正安
,吴统文,梁潇云

大气科学 , 2001,
Abstract: 为得到青藏高原及周围地区平均垂直环流的图像,更好地理解该地区的降水气候,利用美国NCEP/NCAR1961~1990年30年平均的ω、u、v、z等再分析格点资料,计算分析了该地区的平均垂直运动场和经、纬圈环流图,分析了它们的年变化特征和可能的原因.结果表明,该地区冬、夏半年的平均垂直运动场和经、纬圈环流有很大的年变化;揭示了夏季在西北干旱区和华北半干旱区分别存在干旱和半干旱经圈环流,夏季在高原325°N以南还存在巨大的向西纬圈环流等事实;也指出高原大气热源强度的年变化与随后高原及周边地区平均垂直环流的年变化联系密切.高原及周围地区的平均垂直环流特征也能较好地解释各地的降水气候.
The meridional wind at 100 hPa level and the annual change of total ozone over the Northern Hemisphere
北半球100 hPa等压面经向风与臭氧总量年变化

Wu Tongwen,Zheng Guang,Qu Zhang and,
吴统文
,郑光,瞿章,

大气科学 , 1992,
Abstract: The relationship between the meridional wind at 100hPa level and the annual change of total ozone over the Northern Hemisphere has been analysed by secular mean data . It is shown that; they are closely related. The north and south wind at 100 hPa level corresponds to high and low total ozone values , respectively : furthermore , the meridional wind affects the change of total ozone . It fully proves that the annual change of the total ozone is mainly influenced by the lower stratospheric circulation .
Hindcast for the 1998 Summer Heavy Precipitation in the Yangtze and Huaihe River Valley Using BCC_AGCM2.0.1 Model
全球大气环流模式BCC_AGCM2.0.1对1998年夏季江淮流域强降水过程的回报试验研究

JIE Weihua,WU Tongwen,
颉卫华
,吴统文

大气科学 , 2010,
Abstract: 利用中国气象局北京气候中心全球大气环流模式(BCC_AGCM2.0.1) 对1998年6月24日~7月3日发生在我国江淮流域的强降水天气过程进行了回报试验。模式起报时间为1998年6月24日00时, 使用前10天NCEP-II再分析逐时温度、涡度和散度场进行预报前初始协调 (spin-up) 积分, 产生模式初值, 预报时段为1998年6月24日~7月10日, 回报试验结果表明: 模式对全球500 hPa位势高度的天气尺度演变过程具有4~7天的可预报性; BCC_AGCM2.0.1模式对中国区域的降水以及大气环流场具有3~4天的可预报性, 6月24日起报后3天内的预报降水区域位置与实况一致, 但中心强度有所差异。对起报后未来2天的5 mm和10 mm以上的降水预报能力相对较强, ETS评分值达到了0.25以上, HK评分超过了0.4, 降水区域范围预报较为准确, BIA评分趋于1.0。模式对20 mm以上的降水也具有一定的可预报性, 但模式对大于30 mm以上强降水的预报能力较差。
A Study of the Prediction of Regional and Global Temperature on Decadal Time Scale with BCC_CSM1.1 Model
BCC_CSM1.1对10年尺度全球及区域温度的预测研究

GAO Feng,XIN Xiaoge,WU Tongwen,
高峰
,辛晓歌,吴统文

大气科学 , 2012,
Abstract: 近期10~30年时间尺度的年代际预测是第五次耦合模式国际比较计划(CMIP5)重要内容之一.按照CMIP5试验要求,国家气候中心利用气候系统模式BCC_ CSM1.1完成并提交了年代际试验结果.本文评估了该模式年代际试验对10年尺度全球及区域地表温度的预测能力,并通过与20世纪历史气候模拟试验的对比分析,研究模式模拟对海洋初始观测状态的依赖程度.分析结果表明:(1)在有、无海洋初始化条件下,模式均能模拟出1960~2005年间全球10年平均实测地表温度的变暖趋势,但在有海洋初始化条件下,可以明显减小BCC_ CSM1.1模式模拟的全球升温趋势,使得年代际试验比历史试验的结果更接近观测值.这一特点在观测资料相对丰富的南北纬50°以内地区更为显著.(2)在年代际试验预测前期,通过Nudging方法,利用SODA再分析海洋温度资料对模式进行初始化,经过前期8~12月的协调后,模式预测的第1年南北纬50°范围海洋、陆面的平均地表气温接近于观测值(CRUTEM3,HadS ST2).由于模式初值SODA再分析SST资料与HadSST2观测值存在明显的全球大洋系统暖偏差以及模式本身系统偏差的影响,年代际试验模拟的地表气温在2~7年之内,从观测SST状态逐渐恢复到模式系统本身状态.在同组Decadal试验中,陆面和海洋恢复调整的时间长度几乎一致.(3)从10年平均气候异常在区域尺度上的预报技巧来看,有、无海洋初始同化对预测结果影响不大,高预测技巧区主要分布在南半球印度洋中高纬度、热带西太平洋以及热带大西洋区域.(4) SST变化与下垫面热通量密切相关,在热带和副热带海洋区域,长波辐射和感热通量是影响10年时间尺度SST变化较大的物理量,在中高纬度海洋,洋面温度变化主要受潜热通量的影响相对较大.
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