IMPACT OF THE INITIALIZATION ON MESOSCALE MODEL PREDICTION IN SOUTH CHINA   总被引：1，自引：2，他引：1  

DING Wei-yu  WAN Qi-lin  YAN Jing-hua  HUANG Yan-yan  CHEN Zi-tong 《热带气象学报(英文版)》2006,12(1)

1 INTRODUCTION The initial state of the atmosphere is one of the key factors that affect the result of NWP. With the development of increasingly finer NWP, the quality of initial atmospheric state has been drawing more and more attention[1-7].  相似文献   

利用云导风矢量的台风中心自动定位   总被引：7，自引：0，他引：7  

刘正光  喻远飞  吴冰  刘还珠 《气象学报》2003,61(5):636-640

文中提出了一种利用云导风矢量图进行台风中心自动定位的方法。云导风矢量通过对具有一定时间间隔的两幅相关卫星云图进行模板匹配而得出。模板匹配就是根据已知模式的图像在一幅陌生图像中寻找对应于该模式的子图像的过程。根据气象知识 ,台风云系运动的特点是中心平移量大而自旋很弱 ,且台风中心与台风云系整体的移动方向一致 ,因此求出云导风矢量图中与台风整体移动矢量大小和方向一致的矢量集合的最密集区 ,经过数学形态学处理后便得到台风中心  相似文献   

The influence of clouds on surface UV erythemal irradiance     

L. Alados-Arboledas  I. Alados  I. Foyo-Moreno  F. J. Olmo  A. Alcntara 《Atmospheric Research》2003,66(4):273-290

The purpose of this study is to examine the effect of clouds on the ultraviolet erythemal irradiance. The study was developed at three stations in the Iberian Peninsula: Madrid and Murcia, using data recorded in the period 2000–2001, and Zaragoza, using data recorded in 2001. In order to determine the cloud effect on ultraviolet erythemal irradiance, we considered a cloud modification factor defined as the ratio between the measured values of ultraviolet erythemal irradiance and the corresponding clear-sky ultraviolet erythemal irradiance, which would be expected for the same time period and atmospheric conditions. The dependence of this cloud modification factor on total cloud amount, cloud type and solar elevation angle was investigated. The results suggest that the effect of cloud on ultraviolet erythemal irradiance can be parameterized in a simple way in terms of the cloud amount. Our results suggest that the same cloud modification factor model can be used at the three analysed locations estimating the ultraviolet erythemal irradiance with mean bias deviation (MBD) in the range of the expected experimental errors. This cloud modification factor is lower than that associated to the whole solar spectral range, indicating that the attenuation for the ultraviolet erythemal irradiance is lower than that associated to other solar spectral ranges. The cloud modification factor for ultraviolet erythemal irradiance presents dependence with solar elevation, with opposite dependencies with solar elevation for overcast and partial cloud cover conditions, a fact that can be explained in terms of the influence of reflection-enhancement of the ultraviolet irradiance in the last case. Concerning the influence of cloud type, a limited study of two cloud categories, low and medium level and high level, indicated that for overcast conditions, lower clouds presents an attenuation of ultraviolet erythemal irradiance 20% greater than that associated to high level clouds.  相似文献   

Cloud Feedback on SST Variability in the Western Equatorial Pacific in GOALS/LASG Model     

刘辉  张学洪  吴国雄 《大气科学进展》1998,(3)

ＣｌｏｕｄＦｅｄｂａｃｋｏｎＳＳＴＶａｒｉａｂｉｌｉｔｙｉｎｔｈｅＷｅｓｔｅｒｎＥｑｕａｔｏｒｉａｌＰａｃｉｆｉｃｉｎＧＯＡＬＳ／ＬＡＳＧＭｏｄｅｌ①ＬｉｕＨｕｉ（刘辉）,ＺｈａｎｇＸｕｅｈｏｎｇ（张学洪）ａｎｄＷｕＧｕｏｘｉｏｎｇ（吴国雄）Ｓｔａｔ...  相似文献   

中川地区一次负地闪的起始过程研究   总被引：14，自引：7，他引：7  

郄秀书  郭昌明 《高原气象》1998,17(1):34-43

利用ＧＰＳ同步的多点慢天线电场变化仪在甘肃中川地雷暴过程中测量得到的资料,对一次负地闪的起始过程进行了分析。发现地闪产和在击发之前常有持续１７０－３００ｍｓ的去２内放电过程发生,它可有数据不等的Ｋ变化组成。  相似文献   

用双时次GMS/IR通道数据合成动态云图的研究   总被引：2，自引：0，他引：2       下载免费PDF全文

张明席  林忠敏 《应用气象学报》1998,9(4):425-430

数值化动态云图是一种在保留常规云图的基本信息的基础上,增加同窗定量化显示中尺度对流系统（MCS）静态与动态特征功能的新型云图,它比通常的GMS-IR云图具有更多的信息荷载,更丰富的信息内含与更好的实用性。文中提出了以双时次GMS/IR通道数据合成数值化动态云图的技术原理和技术模式。  相似文献   

Seasonal cycle of cloud cover analyzed using Meteosat images     

J. Massons  D. Domingo  J. Lorente 《Annales Geophysicae》1998,16(3):331-341

A cloud-detection method was used to retrieve cloudy pixels from Meteosat images. High spatial resolution (one pixel), monthly averaged cloud-cover distribution was obtained for a 1-year period. The seasonal cycle of cloud amount was analyzed. Cloud parameters obtained include the total cloud amount and the percentage of occurrence of clouds at three altitudes. Hourly variations of cloud cover are also analyzed. Cloud properties determined are coherent with those obtained in previous studies.  相似文献   

Subpixel fractional cloud cover and inhomogeneity effects on microwave beam-filling error     

Damien Lafont  Bernard Guillemet 《Atmospheric Research》2004,72(1-4):149

Using synthetic geometrical clouds and radiative microwave model, we examine the possibility to correct the estimations of liquid water path (LWP) or rain rate with cloud cover measurement. This information may be gotten by co-localized measurements of microwave and infrared/visible measurements on new satellites (TRMM, ADEOS 2, …). In a first step, the effects of fractional cloud cover on microwave brightness temperatures (TB) are investigated in three typical cases of nonprecipitating and precipitating (stratiform and convective) clouds. The beam-filling error (BFE) on brightness temperatures may be analyzed with the known spatial variability using 1D or 3D radiative transfer model. Relationships between BFE and subpixel cloud fraction (CF) are discussed according to the cloud type. We tested several parameters that characterize the horizontal cloud inhomogeneity within a radiometer field of view. BFE was found very sensitive to cloud type and inhomogeneity and is maximum for raining cloud with open spatial structure. In order to account for the uncertainty introduced by the spatial distribution, dependence of BFE on textural-based parameters is also discussed using homogeneity, entropy and an indicator of CF horizontal gradient.  相似文献   

中国地区云对地-气系统辐射强迫温度效应的气候研究   总被引：4，自引：2，他引：4  

刘艳  翁笃鸣 《气象学报》2002,60(6):766-773

文中利用地球辐射平衡试验 (ERBE)和国际卫星云气候计划 (ISCCP)提供的地 气系统行星反射率、射出长波辐射 (OLR)和云量资料 ,计算了中国地区年、月平均总云量对地 气系统短波辐射、长波辐射以及净辐射强迫的温度效应和敏感性系数 ,并讨论了云对各辐射分量强迫的温度效应与总云量的关系。结果表明 :地 气系统云辐射强迫温度效应与总云量间具有较明显的曲线相关。云辐射强迫温度效应及其敏感性系数具有明显的时空变化特点。就中国全国平均而言 ,各月地 气系统云辐射强迫净温度效应一般表现为降温作用。  相似文献   

Organic compounds in radiation fogs in Davis (California)     

Pierre Herckes  Michael P. Hannigan  Laurie Trenary  Taehyoung Lee  Jeffrey L. Collett  Jr.   《Atmospheric Research》2002,64(1-4)

New stainless steel active fogwater collectors were designed and used in Davis (CA, USA) to collect fogwater for the speciation of organic matter. Organic compounds in fog samples were extracted by liquid–liquid extraction and analyzed by gas chromatography coupled to mass spectrometry. Numerous organic compounds, including various alkanes, polycyclic aromatic hydrocarbons (PAH) and alkanoic acids, have been identified in the fogwater samples. Higher molecular weight (MW) compounds are preferentially associated with an insoluble phase inside the fog drops, whereas lower molecular weight and more polar compounds are found predominantly in the dissolved phase. Concentrations in the dissolved phase were sometimes much higher than estimated by the compounds' aqueous solubilities.  相似文献