500hPa环流变化与山东春季降水异常   总被引：2，自引：1，他引：1  

高留喜  安兴琴  刘秦玉  黎清才  高慧君 《气象科学》2004,24(4):440-447

应用SVD技术,诊断分析了北半球500hPa高度场与山东春季降水的关系。结果表明：山东春季降水与北半球500hPa高度场关系密切,山东春季降水与东亚上空500hPa高度场具有很好的同步联系。前期(冬季)日本东北部500hPa高度场是影响山东南部春季降水的关键区,具有预测意义。500hPa高度距平场东高西低型是造成山东春季降水的主要大气环流形势,西高东低型是造成山东少雨的主要大气环流形势。  相似文献   

临沂市地质灾害预警预报与指挥系统的设计与实现     

密长林  孙景广  安振  王祥 《国土资源信息化》2012,(4):40-43

本文结合国内外有关地质灾害预警预报的相关理论研究,论述了临沂市地质灾害预警预报与指挥系统的总体框架和功能设计,介绍了本系统的预警预报、应急指挥、态势标绘等功能。系统旨在逐步提高临沂市的地质灾害预警预报技术水平,为各级政府制定国民发展计划和城镇规划提供重要的科学依据,为减灾防灾提供技术支撑。  相似文献   

Decreasing trend of sunshine hours and related driving forces in Southwestern China   总被引：1，自引：0，他引：1  

Li Zongxing  Feng Qi  Zhang Wei  He Yuanqing  Wang Xufeng  Norm Catto  An Wenlin  Du Jiankuo  Chen Aifang  Liu Li  Hu Meng 《Theoretical and Applied Climatology》2012,109(1-2):305-321

Total hours of sunshine are one of the most important factors affecting climate and environment, and its long-term variation is of much concern in climate studies. Trends of temporal and spatial patterns in sunshine hours and related climatic factors over southwestern China are evaluated for the period 1961–2009 based on data from 111 standard meteorological stations. The results showed that southwestern China is experiencing a statistical decrease of sunshine hours, at the rate of 31.9 h/10a during 1961–2009. The decline was particularly strong in summer, whereas it is nonsignificant in winter. Spatially, statistically significant decreases of sunshine hours mainly occurred in lower altitude regions, especially in the Sichuan basin and Guizhou plateau. Sunshine hours have a high correlation with wind speed, relative humidity, precipitation, cloud cover, surface downwards solar radiation flux, and cloud water content, with wind speed showing the strongest relationship to sunshine hours, implicit in the close correlation (temporally and spatially) between the two variables. Changing water vapor and cloud cover influence sunshine hours in southwestern China. In addition, the increased surface downwards solar radiation flux also made some contribution to a rise of sunshine hours during 1991–2009. The larger decreasing trends of sunshine hours at urban stations than rural stations may reflect the effect of urbanization on sunshine hours. Variations are dominated by the comprehensive functions of multiple factors owing to the complex nature of effects on sunshine hours.  相似文献   

Vertical structure variability and equatorial waves during central Pacific and eastern Pacific El Ni?os in a coupled general circulation model     

B. Dewitte  J. Choi  S.-I. An  S. Thual 《Climate Dynamics》2012,38(11-12):2275-2289

Recent studies report that two types of El Ni?o events have been observed. One is the cold tongue El Ni?o or Eastern Pacific El Ni?o (EP El Ni?o), which is characterized by relatively large sea surface temperature (SST) anomalies in the eastern Pacific, and the other is the warm pool El Ni?o (a.k.a. ‘Central Pacific El Ni?o’ (CP El Ni?o) or ‘El Ni?o Modoki’), in which SST anomalies are confined to the central Pacific. Here the vertical structure variability of the periods during EP and CP is investigated based on the GFDL_CM2.1 model in order to explain the difference in equatorial wave dynamics and associated negative feedback mechanisms. It is shown that the mean stratification in the vicinity of the thermocline of the central Pacific is reduced during CP El Ni?o, which favours the contribution of the gravest baroclinic mode relatively to the higher-order slower baroclinic mode. Energetic Kelvin and first-meridional Rossby wave are evidenced during the CP El Ni?o with distinctive amplitude and propagating characteristics according to their vertical structure (mostly first and second baroclinic modes). In particular, the first baroclinic mode during CP El Ni?o is associated to the ocean basin mode and participates to the recharge process during the whole El Ni?o cycle, whereas the second baroclinic mode is mostly driving the discharge process through the delayed oscillator mechanism. This may explain that the phase transition from warm to neutral/cold conditions during the CP El Ni?o is delayed and/or disrupted compared to the EP El Ni?o. Our results have implications for the interpretation of the variability during periods of high CP El Ni?o occurrence like the last decade.  相似文献   

Recent and future sea surface temperature trends in tropical pacific warm pool and cold tongue regions   总被引：3，自引：2，他引：1  

Soon-Il An  Ji-Won Kim  Seul-Hee Im  Beak-Min Kim  Jae-Heung Park 《Climate Dynamics》2012,39(6):1373-1383

Using coral data, sea surface temperature (SST) reanalysis data, and Climate Model Intercomparison Project III (CMIP3) data, we analyze 20th-century and future warm pool and cold tongue SST trends. For the last 100?years, a broad La Nina-like SST trend, in which the warming trend of the warm pool SST is greater than that of the cold tongue SST, has appeared in reanalysis SST data sets, 20C scenario experiments of the CMIP3 data and less significantly in coral records. However, most Coupled General Circulation Models subjected to scenarios of future high greenhouse gas concentrations produce larger SST warming trends in cold tongues than in warm pools, resembling El Nino-like SST patterns. In other words, warmer tropical climate conditions correspond to stronger El Nino-like response. Heat budget analyses further verify that warmer tropical climates diminish the role of the ocean’s dynamic thermostat, which currently regulates cold tongue temperatures. Therefore, the thermodynamic thermostat, whose efficiency depends on the mean temperature, becomes the main regulator (particularly via evaporative cooling) of both warm pool and cold tongue temperatures in future warm climate conditions. Thus, the warming tendency of the cold tongue SST may lead that of the warm pool SST in near future.  相似文献   

天津武清地区云凝结核变化特征     

王婷婷  孙俊英  沈小静  邓兆泽  张养梅  安林昌  张晓春  颜鹏  梁文德  陈丽丽 《气象科技》2012,40(3):466-473

利用2009年11—12月在天津武清气象局测量的云凝结核(CCN:Cloud Condensation Nuclei)浓度资料以及气溶胶数谱分布的观测资料,分析了武清地区在不同过饱和度(0.1%～1.0%)下云凝结核浓度及活化率的变化特征。结果表明:武清地区冬季CCN数浓度变化范围很大,过饱和度1%时,浓度变化范围为4000～32000cm-3,且浓度受风速影响明显,风速2级以下CCN数浓度很高,过饱和度1%时,其平均浓度可达16000cm-3,但对于4级风速以上CCN平均浓度为4000cm-3左右;在过饱和度0.1%～0.4%间CCN浓度变化较大,过饱和度每增加0.1%,CCN浓度增加值平均约为过饱和度0.4%～1.0%间浓度增量的5倍。低过饱和度(0.1%、0.2%)下,活化率受风速影响明显,1级风速下的CCN活化率约为4级风速下的3倍,但在过饱和度1%时活化率则相差不大。CCN浓度的日变化呈双峰型,峰值时刻为北京时间08:00和18:00左右,活化率的日变化则呈双谷型,这主要是受局地排放影响的结果。利用指数函数拟合各风速下CCN浓度过饱和度谱,表明该地谱型为典型的大陆型。  相似文献   

地基GPS水汽总量在人工增雨中的应用     

谢娜  李国平  李昕翼  安峡 《气象科技》2012,40(4):666-670

利用成都市地基GPS综合应用网的观测数据,反演出大气水汽总量,并结合多普勒天气雷达探测的垂直积分液态水含量(VIL),分析了这两种新型大气水汽探测资料在人工影响天气作业中的变化特征,初步得出了GPS大气水汽总量(GPS PWV)与人影作业前后降雨量的关系。研究表明:GPS PWV与人工增雨过程有较好的对应关系,人影作业后1～3h伴随小时雨量的增大GPS PWV有下降,体现了催化剂将空中部分冰面过饱和水汽凝华核化转化为降水过程。GPS反演的水汽资料结合新一代多普勒天气雷达探测的液态水资料在指导人工影响天气作业和短临天气预报方面具有良好的应用前景。  相似文献   

全边界层选用相似理论对O3、NOx浓度及沉降的影响     

屈玉  安俊岭  周慧  叶小峰 《气候与环境研究》2009,14(4):363-372

将广泛应用于东亚地区的LLA(Lurmann Lloyd Atkinson)化学机制耦合到欧拉型区域空气质量模式(RAQM),并考虑区域污染物长期模拟研究中降水随时间变化的非均匀性,讨论了湍流参数化过程中相似理论在近地层和全边界层的应用对湍流垂直扩散系数(Kz)与干沉降速度(V),O3与NOx浓度的影响。结果表明,全边界层应用相似理论明显低估了Kz值,近地层50m处Kz值被低估20%以上,750m处其值被低估约70%;O3、NOx的干沉降速度在日本东部与南部海域被低估了10%以上,在朝鲜半岛东部和西部海域模拟值普遍偏高。Kz和干沉降速度的不同直接影响污染物的浓度和沉降量分布。Kz值的被低估对NOx浓度有明显影响,在近地层50m处NOx浓度最大可增加约30%,整个边界层中NOx平均浓度除台湾省东北海域外普遍增加5%~20%。O3浓度则受干沉降作用的影响较大。虽然近地层、全边界层分别应用相似理论都较好地模拟了O3与NOx峰值浓度出现的时间,但相似理论应用于全边界层会引起较大的误差。即使是大区域、长期空气质量模拟研究,也建议相似理论仅应用于近地层,且模式第一层高度应设置在常通量层内。  相似文献   

江西省一次冷空气过程中的灰霾天气过程分析   总被引：3，自引：0，他引：3  

肖安  徐星生  卢敏 《气象科技》2010,38(1):49-52

利用江西省常规气象观测资料、探空站资料和空气污染资料,对2008年12月12～13日江西省的一次大范围灰霾天气过程进行了综合分析研究。结果表明:横槽转竖引导冷空气南下和中层高度的干燥暖舌共同影响,是这次灰霾天气过程发生的天气形势背景;冷空气受到700hPa干暖舌的抑制作用,形成低层偏冷,中层偏暖的"逆温"结构,导致了大范围的灰霾天气过程出现、维持;空气相对湿度较低,受昼夜温差和冷空气的共同影响,造成轻雾和灰霾天气之间频繁转换;较低的混合层高度导致近地面污染物以水平运动为主,在遇到较高海拔的山脉阻挡后,沿山脉边缘向东西方向扩展,汇集到平原、河谷地区,降低这些地区的能见度,导致灰霾区域由"南北向型"演变成了"东西向型"。  相似文献   

特征级高分辨率遥感图像快速自动配准     

何梦梦  郭擎  李安  陈俊  陈勃  冯旭祥 《遥感学报》2018,22(2):277-292

随着遥感图像分辨率的日益提高,遥感图像的尺寸和数据量也不断地增大,同时随着遥感应用的发展,对图像配准的性能也提出越来越高的要求,基于此,提出一种特征级高分辨率遥感图像快速自动配准方法。首先,对图像进行Haar小波变换,基于小波变换后的近似图像进行配准以提高配准速度;其次,根据不同的遥感图像来源使用不同的特征提取方法(光学图像使用Canny边缘提取算子,SAR图像使用Ratio Of Averages算子),并将线特征转化为点特征;然后,依据特征点间最小角与次小角的角度之比小于某一阈值来确定初始匹配点对;最后,利用改进的随机抽样一致性算法滤除错误匹配点对,并结合分块思想均匀选取匹配点对计算仿射变换参数,进一步提高配准精度。为了验证本文方法的有效性,选择高分辨率World View-2图像、Pleiades图像和Terra SAR图像进行了实验,并与典型的SIFT算法、SURF算法进行比较分析,采用匹配率、匹配效率、均方根误差和时间消耗4个定量评价指标来客观评价算法的配准性能。实验结果表明,本文方法具有较好的有效性,且在不同的情况下具有较高的配准精度。本文提出的特征级高分辨率遥感图像快速自动配准方法,多组高分辨率遥感图像数据的配准实验结果表明该方法能快速实现并具有较高的配准精度和较好的鲁棒性。  相似文献