准噶尔盆地西北缘一次大到暴雨天气过程分析     

孙东霞 《沙漠与绿洲气象(新疆气象)》2013,7(3)

摘要：通过分析2010年6月２8～２9日发生在准噶尔盆地西北缘的一次大到暴雨天气,揭示了形成这次强降水天气的环流背景特点、物理量和雷达回波特征。结果显示：冷暖气团在克拉玛依地区附近相遇产生的中尺度锋生现象触发了本次暴雨天气过程。表现最明显的特征是：高空槽移动缓慢,中层切变线不断南压、低层中尺度系统维持,冷暖气团在区域强烈交汇。暴雨区雷达速度场有明显的风场幅合。对流降水云团强度、移向变化的预测,是此类天气临近预报的关键和难点。  相似文献   

The erodibility of some Nigerian soils: A comparison of rainfall simulator results with estimates obtained from the Wischmeier nomogram     

A. Vanelslande  R. Lal  D. Gabriels 《水文研究》1987,1(3):255-265

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Annual and monthly rainfall data generation schemes   总被引：2，自引：2，他引：0  

N. E.?ünal  H.?AksoyEmail author  T.?Akar 《Stochastic Environmental Research and Risk Assessment (SERRA)》2004,18(4):245-257

Synthetic annual and monthly rainfall data series are generated by using autoregressive (AR) processes, Thomas-Fiering (TF) model, method of fragments (F) and its modified version (MF), two-tier (TT) model, and a newly developed wavelet (W) approach. It is seen that the W approach is as well in preserving the statistical behavior of the observed data series as the classical annual and monthly hydrological data generation schemes used in this study. The W approach is found even better in replacing some particular characteristics such as the mean of the sequence and correlation between the successive months in the series. It is, therefore, proposed as a new annual and monthly hydrological data generation scheme.  相似文献   

青藏高原东部暴雨强降水的特征     

赵彩 《贵州气象》2012,36(6):1-4

该文简要地介绍了贵州省气候中心近期主持完成的一项关于青藏高原东部暴雨强降水成因及特征的研究成果。这一成果使用多种方法综合研究了青藏高原东部暴雨的标准、暴雨的水汽通道、暴雨的天气气候特征、暴雨的小范围、短历时特征、暴雨的高效率特征、夜雨特征、暴雨强降水的巨大地形差异、青藏高原特有的雪暴强降水特征、暴雨面雨量的计算、最大可能降水量的估算、暴雨过程的地面径流特征、青藏高原东部的水平衡特征等课题,填补了青藏高原暴雨研究的空白。  相似文献   

Recurrent daily OLR patterns in the Southern Africa/Southwest Indian Ocean region,implications for South African rainfall and teleconnections     

Nicolas Fauchereau  B. Pohl  C. J. C. Reason  M. Rouault  Y. Richard 《Climate Dynamics》2009,32(4):575-591

A cluster analysis of daily outgoing longwave radiation (OLR) anomalies from 1979 to 2002 over the Southern Africa/Southwest Indian Ocean (SWIO) region for the November to February season reveals seven robust and statistically well separated recurrent patterns of large-scale organized convection. Among them are three regimes indicative of well defined tropical–temperate interactions linking the hinterland parts of Southern Africa to the mid-latitudes of the SWIO. Preferred transitions show a tendency for an eastward propagation of these systems. Analysis of daily rainfall records for South Africa shows that six of the OLR regimes are associated with spatially coherent and significant patterns of enhanced or reduced daily rainfall over the country. Atmospheric anomalies from the NCEP/DOE II reanalysis dataset show that the OLR regimes are associated with either regional or near-global adjustments of the atmospheric circulation, the three regimes representative of tropical–temperate interactions being in particular related to a well-defined wave structure encompassing the subtropical and temperate latitudes, featuring strong vertical anomalies and strong poleward export of momentum in the lee of the location of the cloud-band. The time-series of OLR regimes seasonal frequency are correlated to distinctive anomaly patterns in the global sea-surface-temperature field, among which are shown to be those corresponding to El Nino and La Nina conditions. The spatial signature of El Nino Southern Oscillation’s (ENSO) influence is related to the combination of an increased/decreased frequency of these regimes. It is shown in particular that the well-known “dipole” in convection anomalies contrasting Southern Africa and the SWIO during ENSO events arises as an effect of seasonal averaging and is therefore not valid at the synoptic scale. This study also provides a framework to better understand the observed non-linearities between ENSO and the seasonal convection and rainfall anomalies over the region.  相似文献   

有限区域流函数和速度势的3种求解方法在分析台风Bilis暴雨增幅中的比较研究     

任晨平  曹洁  王黎娟  崔晓鹏 《气候与环境研究》2013,18(6):721-732

将有限区域流函数、速度势求解中常用的两种张驰法(即理查逊法和加速利布曼法)与调和—余弦谱展开法(H-C法)进行了比较,理论研究表明:H-C法单独考虑边界影响分量,物理意义明确,且不会丢失边界上的天气系统;从计算上看,H-C法重建的风场能精确还原原始风场,且计算效率明显高于两种张驰法,即收敛更快。通过在台风Bilis(0604)暴雨增幅过程诊断中的应用发现,常用的两种张驰迭代方法在求解有限区域流函数和速度势的问题上效果都不是很好,即:用理查逊法和加速利布曼法计算的流函数和速度势重建的风场与原始风场差别较大,不能准确还原原始风场;用H-C法不仅计算效率高,还原的风场与原始风场差异极小,且不受南边界较强的西南季风涌影响,在暴雨增幅前期能较好地反映与暴雨增幅相关的强辐合信号。因此,可用H-C法计算得到的无辐散风和无旋风对有限区域的天气系统进行更深入的动力结构分析。  相似文献   

易语言调用surfer 8．0自动绘制临汾市雨量等值线图     

贾康民  王淑凤  杨晓芳  贺春荣  刘睿 《山西气象》2010,(3):42-44

利用易语言调用surfer8．0绘图软件,设计实现临汾市17个县（市）气象站雨量等值图形化功能。该功能可以方便快捷地实现临汾市雨量等值图的图形化显示、输出和保存等工作。绘制的雨量等值线图结果直观、快捷、方便、准确,提高了工作效率。  相似文献   

Rainfall yield characteristics of electrical storm observed in the Spanish Basque Country area during the period 1992–1996     

A. Ezcurra  J. Saenz  G. Ibarra-Berastegi  J. Areitio 《Atmospheric Research》2008,89(3):233-242

This paper is focused on the study of rainfall yield characteristics of electrical storms observed over the Northern Iberian Peninsula during 1992–1996. To this aim Principal Components Analysis (PCA) and Self-Organizing Maps (SOM) method have been used. The SOM method is a group of artificial neural networks based on the topological properties of the human brain. Results clearly suggest that there exist three different meteorological patterns that are linked to the characteristics of electrical events found in the study area. In winter, most of the electrical events are formed under oceanic advection (NW air fluxes). On these cases, mean rainfall yield estimates reach values of 700 10⁴ m³ per cloud to ground lightning flash (CG flash). During summer most frequent electrical storms are associated to local instability shooting by surface heating with advection of humidity coming from the Iberian Peninsula. Under these meteorological situations, rain is scarcer if compared with oceanic events but lightning CG counts reach the maximum values found in the area (about 10 CG counts per 20 × 20 km² and day) giving this way the smallest rainfall yield with a mean value of 15 10⁴ m³ per CG flash. Iberian air fluxes associated with cold air in upper parts of the atmosphere represent the third meteorological pattern found. This pattern is most common in spring and autumn but is not unusual in the rest of the seasons. In those cases mean rainfall yield in the area is about 150 10⁴ m³ per CG flash. In all electrical episodes K instability index is greater than 15 °C but in the most lightning producing events, this index reaches in the area values greater than 24 °C. PCA results pointed out that there exists a relationship between rain and CG counts expressed by the first principal component computed from standardized data. However, we must notice that no event is solely linked to this axis, since a seasonal influence which decreases lightning production when rain increases is always present. Results found are of great interest for short term forecasting of flashfloods in mountainous areas like the Spanish Basque Country region.  相似文献   

Fog collection in the western Mediterranean basin (Valencia region, Spain)   总被引：1，自引：0，他引：1  

María J. Estrela  Jos A. Valiente  David Corell  Milln M. Milln 《Atmospheric Research》2008,87(3-4):324

Four different mountainous locations were selected in the Valencia region, East coast of the Iberian Peninsula, for fog water collection studies. Data for 2004 were obtained by means of an instrument ensemble consisting essentially of a passive cylindrical fog water collector, a raingauge, a wind direction and velocity sensor and a temperature and humidity probe. An approximate data reduction technique was also found for this specific ensemble to eliminate the simultaneous rain water component from the fog water measurements. Main results indicate that fog water collection holds significant potential in this region, and especially for southern locations. Annual rates of fog water yield can be as high as 7.0 l/m²/day in the southern locations, in contrast to 2.0 l/m²/day collected at one site in a northern location. The highest summer fog water yield was 4.6 l/m²/day, a relatively large value. Except for the summer period, fog episodes delivering sizeable water volumes are inherently coupled to rainfall. Hourly frequencies of fog collection were also examined to show a distinct daily cycle in summer, denoting orographic fog formation during this period. Lastly, winds were analysed to resolve the most suitable directions for fog collector alignment.  相似文献   

Scaling of tropical rainfall as observed by TRMM precipitation radar     

Mekonnen Gebremichael  Witold F. Krajewski  Thomas M. Over  Yukari N. Takayabu  Phillip Arkin  M. Katayama 《Atmospheric Research》2008,88(3-4):337-354

We used a three-year (1998–2000) dataset of TRMM Precipitation Radar observations to investigate the scaling properties of spatial rainfall fields. This dataset allows consideration of spatial scales ranging from about 4.3 km to 138 km and short temporal scales corresponding to the sensor overpasses. The focus is on the marginal spatial moment scaling, which allows estimation of the scaling parameters from a single scene of data. Here we present a global perspective of the scaling properties of tropical rainfall in terms of its spatial variability, atmospheric forcing, predictability, and applicability. Our results reveal the following: 1) the scaling parameters exhibit strong variability associated with land/ocean contrast and mean precipitation at the synoptic scale; 2) there exists a one-to-one relationship between the scaling parameters and the large-scale spatial average rain rate of a universal functional form; 3) the majority of the scenes are consistent with the hypothesis of scale invariance at the moment orders of 0 and 2; 4) relatively there are more scale-invariant rain scenes over land than over ocean; and 5) for the scenes that are non-scale-invariant, deviation from scale-invariance mainly arises from the increasingly intermittent behavior of rainfall as spatial scale decreases. These results have important implications for the development and calibration of downscaling procedures designed to reproduce rainfall properties at different spatial scales and lead to a better understanding of the nature of tropical rainfall at various spatial resolutions.  相似文献