Evolution of aerosol vertical distribution during particulate pollution events in Shanghai          下载免费PDF全文

张云伟  张群  冷春鹏  张德芹  成天涛  陶俊  张仁健  贺千山 《Acta Meteorologica Sinica》2015,29(3):385-399

A set of micro pulse lidar(MPL)systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011.Three typical particulate pollution events(e.g.,haze)were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer(PBL)during these pollution episodes.The aerosol vertical extinction coefficient(VEC)at any given measured altitude was prominently larger during haze periods than that before or after the associated event.Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering,leading to different aerosol vertical distribution structures.Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions.Several peaks in aerosol VECs were found at altitudes above 1 km during the dust-and bioburning-influenced haze events.Aerosol VECs decreased with increasing altitude during the local-polluted haze event,with a single maximum in the surface atmosphere.PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events;subsequently,PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages.The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.  相似文献   

气候变化对中国农业旱灾损失率的影响及其南北区域差异性   总被引：4，自引：1，他引：3  

张强  韩兰英  郝小翠  韩涛  贾建英  林婧婧 《气象学报》2015,73(6):1092-1103

在全球变暖背景下,干旱灾害对中国农业生产的影响日益严重,然而由于旱灾损失的复杂性及其显著的区域差异,至今对中国农业旱灾损失规律及其影响机制的认识十分有限。文中利用1961年以来中国农业干旱灾害的灾情资料和常规气象资料,系统分析了近50年来中国农业干旱灾害不同受灾强度分布比率和综合损失率等指标的变化趋势及其在北方和南方的区域差异,研究了20世纪90年代的气温突变对农业旱灾损失率的影响特征,探讨了农业旱灾综合损失率对气温和降水等气候要素变化的依赖关系及其在气候空间的分布特征。结果发现,在气候变化背景下,近50年来中国农业旱灾综合损失率平均每10 a约增加0.5%,风险明显增大。而且,北方综合损失率每10 a约增加0.6%,高出南方1倍,风险增大的速度明显比南方快;北方农业旱灾几乎在很宽松的气温条件下就可以发生,而南方更多发生在气温较高的年份。并且,在气温突变后,变化趋势明显加剧,全中国综合损失率约增加了0.9%,风险明显增高;而且北方综合损失率的增值高达1.8%,是南方的4倍还多,气候突变对北方农业旱灾风险的影响明显比南方更凸出。综合损失率在北方对降水变化的响应要更敏感,而在南方对气温变化的响应更敏感。同时,关键影响期降水对综合损失率的影响比全年降水影响更显著;北方的关键影响期作用比南方更凸出。这些新的科学认识对中国农业旱灾防御具有重要意义。  相似文献   

BJ-RUC产品在小区供暖供回水温度预报的应用研究   总被引：1，自引：1，他引：0  

李迅  冯涛  丁德平  谢庄 《气象》2015,41(2):234-239

利用气象部门快速更新的BJ-RUC(Beijing-Rapid UpdateCycle)数值预报系统获得的24 h逐时的室外温度预报资料,应用能量平衡原理,建立建筑物热损失方程和供热量方程,从而推导出室外温度和室内温度、供水、回水温度的预报模型。用此模型对2010年3月1—15日期间的供、回水温度进行预报模拟,与北京市海园物业供热单位实况值进行对比分析。检验结果表明,该模型模拟的室内温度与设计要求的室内温度(20℃)之间的均方根误差为0.25℃,海园物业室内温度监测点数值与20℃之间的均方根误差为1.53℃。模拟的供、回水温度与海园物业监测点供水温度的均方根误差分别为3.69℃和3.80℃。  相似文献   

基于多普勒天气雷达的两种垂直风廓线反演方法的对比分析   总被引：1，自引：0，他引：1  

肖艳姣  万玉发  吴涛  王珏 《高原气象》2015,34(1)

利用2010年阳江高精度探空仪国际比对试验中观测的探空测风资料、CINRAD-SA型多普勒天气雷达体扫资料及基于PUP-VAD方法反演的垂直风廓线产品资料,使用三种不同复杂程度的分层VVP方法(VVP1、VVP2和VVP3)反演了阳江雷达站上空的垂直风廓线,以探空测风为参考,以平均风向、风速均方差和相关系数作为评估因子,将雷达站周围降水回波分布分为较均匀和不均匀两种情况,对比分析了基于分层VVP方法和PUP-VAD方法反演的垂直风廓线。结果表明,相比PUPVAD方法,分层VVP方法都能提供更实用、质量更好的垂直风廓线,特别是在雷达周围降水回波分布不太均匀的情况下。主要原因是在某一高度,相比PUP-VAD方法只分析某仰角某距离圈上的径向速度资料来说,分层VVP方法是通过对该高度层10~100 km范围内的所有有效径向速度资料进行多元线性回归来求解该高度层的平均水平风向、风速,受资料覆盖率的影响程度要小于PUP-VAD方法。  相似文献   

南大洋淡水强迫对南半球环状模的影响分析   总被引：1，自引：0，他引：1  

马浩  李正泉  冯涛  刘成彦 《气象与环境学报》2015,(3):81-88

南半球环状模是南半球热带外大气环流变异的主导模态,对南半球海洋—大气—海冰耦合系统有重要的影响。冰川融化激发的淡水强迫是南大洋的一种重要外强迫。在历史气候记录中,南大洋淡水通量异常曾引发数次全球性气候异常事件。基于海—气完全耦合模式FOAM,在60°S以南的海洋中施加强度为1.0 Sv的理想化淡水通量异常,分析南半球环状模的响应。结果表明：南大洋淡水通量异常可使局地西风增强,且西风的增强在垂向各个层次上均有体现。西风强度的变化导致对流层中大气斜压性增强,平流层中大气斜压性减弱。此外,淡水强迫使环状模的年际变率振幅显著减弱,而年代际变率开始增强,谱能量的变化具有垂向一致性。海温和海冰等外强迫因子的变化对环状模年代际振幅的增强具有重要意义。  相似文献   

Discussion on the complete-form vorticity equation and slantwise vorticity development          下载免费PDF全文

王秀明  周小刚  陶祖钰  刘华 《Acta Meteorologica Sinica》2016,30(1):67-75

The complete form of the vertical vorticity tendency equation (the complete-form vorticity equation) is derived from the Ertel potential vorticity equation to contain thermodynamic factors. In this study, a new complete-form vorticity equation, which has the same form as the original complete-form vorticity equation, is deduced from the absolute vorticity vector equation combined with the continuity equation and the expression of three-dimensional (3D) entropy gradient. By comparing the complete-form vorticity equation with the classical vertical vorticity equation, it is found that regardless of whether or not the isentropic surface is tilting, the two vorticity equations are in essence the same. The “baroclinic term” of the complete-form vorticity equation is exactly equal to the solenoidal term of the classical one, and there is a significant amount of cancellation between the two baroclinic items (the “slantwise term” and the horizontal vorticity change term) in the complete-form vorticity equation. In operational weather analysis, the tilt of the isentropic surface can be diagnosed according to the density of the isotherm on the upper-level isobaric map. For synoptic-scale motion, the vertical vorticity produced by the tilt of the isentropic surface is due to the contribution of atmospheric baroclinicity, which is measured by the solenoid. The 3D solenoid is parallel to the isentropic surface, so the more tilted the isentropic surface, the bigger the projection of the 3D solenoid in the vertical direction. The baroclinic contribution can be interpreted based on the PV thinking theory, but the relationship between the vorticity field and the potential vorticity field is not immediate.  相似文献   

分块DPCM与5/3整数小波变换结合的天文图像无损压缩     

朱贵富  邓辉  王锋  季凯帆 《天文研究与技术》2011,8(1)

针对海量的天文图像数据与有限的存储空间和带宽资源之间矛盾日益突出这一问题,提出一种无损压缩方法,首先将超大天文图像分块,再使用差分脉冲编码调制和5/3整数小波变换,最后使用霍夫曼算法编码。对该方法的原理和具体实现做了详细的分析与介绍,通过实验验证该方法比天文中常用的tar、PKZip、WinZip、WinRar软件在压缩比上分别提高了30%、29%、26%、2%,压缩速度远大于WinZip和WinRar;且该算法实现简单,适合硬件实现和利于并行处理。  相似文献   

Dependence of the holmberg effect on separations between paired galaxies     

Xin-Fa Deng  Yong Xin  Jiang Peng  Ping Wu 《Astrophysics》2010,53(3):342-350

To investigate the dependence of the Holmberg effect of paired galaxies on three-dimensional separations, we have constructed four subsamples characterized by three-dimensional separations s ≤ 50 kpc, 50 kpc < s ≤ 100 kpc , 100kpc < s ≤150kpc , and 150 kpc < s ≤ 200 kpc , respectively. In this study, linear correlation coefficients and surplus standard deviations of color indices, luminosity, and size between two components of paired galaxies are calculated. It is found that there is a weak tendency for correlation coefficients of color indices to increase with decreasing three-dimensional separations, but such a tendency does not exist for ones of luminosity and size. We also note that there is no tendency for surplus standard deviations to decrease with decreasing three-dimensional separations. This suggests that it is still very difficult to clearly affirm the dependence of the Holmberg Effect of paired galaxies on three-dimensional separations.  相似文献   

Secular period decreasing of detached chromospherically active binaries     

Chang Qing Luo  Xiao Bin Zhang  Li Cai Deng  Yang Ping Luo  Zhi Quan Luo  Shu Zheng Yang 《Astrophysics and Space Science》2010,327(1):9-17

The long-term orbital period changes of a large sample of detached chromospherically active binaries (CABs) were studied. Eleven such systems were found to be undergoing secular period decreases with the rates of ?6.3×10^?9 to ?1.1×10^?6 days per year. The period decreasing rates are found to vary depending on the orbital period. The longer the orbital period is, the more rapidly the period decreases. Following Stepien (Mon. Not. R. Astron. Soc. 274:1019, 1995), the period decreasing rate predicted by angular momentum loss (AML) caused by magnetic wind is computed for each system. A comparison between the observed and calculated period decreasing rates shows that the former values are obviously larger than the latter by 1–3 orders of magnitude. It suggests that the magnetic wind is not likely the determinant mechanism driving the AML in these systems. Finally, the orbital angular momentum (AM) and the rate of AML, $\dot{J}$ , are computed for each system. It shows that the AM have a similar change with the orbital period like dP/dt does, but $\log\dot{J}/J$ presents no strict changing with the kinematical ages.  相似文献   

厦门国家级珍稀海洋物种自然保护区文昌鱼(Branchiostoma belcheri)种群健康评价     

黄良敏  黎中宝  吝涛  李元跃  陈融斌  王家樵  陈强  李军 《海洋与湖沼》2013,44(1):103-110

利用2009-2010年四个季度月用底栖生物抓斗式采样器捕获的文昌鱼样品,从其资源分布、年龄结构、生物学和生态学特征等方面对厦门国家级珍稀海洋物种自然保护区文昌鱼的种群健康状况进行评价研究.结果表明:(1)文昌鱼种群资源分布衰减趋势明显,只在黄厝—前埔海区、小嶝岛—角屿海区和南线—十八线海区3个核心区还有分布,但资源密度低,分布范围狭小,而在鳄鱼屿实验区未能发现.(2)文昌鱼体重与体长之间关系:W=6.6895×10-4L3.1818;体长与体质量生长方程分别为:厶=65.63[1-e-0.68(t+032)],Wt=404.62[1-e-0.68(t+032)]3.1818;夏季、冬季航次的优势体长组分别为25-35mm和35-45mm,优势体重组分别为25-50mg和50-100mg;秋季低龄鱼较多,而冬季高龄鱼比例较高.(3)采用ELEFAN Ⅰ技术分析了厦门文昌鱼的Von Bertalanffy生长参数K、L∞、总死亡系数Z、自然死亡系数M和开发率E,发现其生长参数K值较大,自然死亡系数较高,开发率较大(0.69).综之,厦门自然保护区内的文昌鱼种群健康状况整体不佳,应注意资源保护,加强保护文昌鱼栖息地的底质和水质以及防止过度捕捞以实现其资源可持续利用.  相似文献