上海菜区人工模拟暴雨入渗试验研究初报          下载免费PDF全文

杨秋珍 李军谈建国  杨星卫汪治澜 盛平洪嘉琏  刘彩堂李林 《应用气象学报》1998,9(3):364-370

根据水量平衡原理,采用人工模拟降雨入渗实验装置,对上海新老菜区土壤进行不同墒情状态下的多种雨强人工模拟降雨入渗试验,获取了上海菜区代表性土壤的暴雨入渗过程动态实验数据和入渗基本参数,并分析了土壤水分变化规律,可作为上海菜区开展暴雨雨涝灾情评估的依据,对类似土壤条件的长江流域平原地区菜田,也有一定的参考价值。  相似文献   

高原地形对四川盆地西部突发性暴雨影响的数值试验   总被引：14，自引：2，他引：12  

郁淑华  滕家谟  何光碧 《大气科学》1998,22(3):379-383

用η模式对1995年8月24日四川盆地西部一次突发性暴雨进行了数值模拟和地形减半、无地形数值试验。由对数值模拟与试验的结果分析得出:（1）青藏高原地形有利于高原东麓暴雨区的扩大与强度加大。（2）高原地形对其以北的天气系统南伸和以南的天气系统北扩有阻碍作用。（3）高原地形可影响高原附近以东地区的物理特征场分布,从而影响暴雨区的位置与强度。  相似文献   

亚洲冬夏季风对ENSO事件的响应   总被引：121，自引：26，他引：95  

陶诗言  张庆云 《大气科学》1998,22(4):399-407

根据NCEP/NCAR_1980～1995年的再分析资料,分析了1980年以来5个El Ni?o和La Ni?a年冬、春和夏季200、500和850 hPa合成高度场、风场、流函数场及温度场。发现在冬季El Ni?o（La Ni?a）年亚洲上空的环流型不利（有利）于寒潮向南爆发,导致亚洲冬季风和大洋洲夏季风弱（强）。在El Ni?o（La Ni?a）年冬季华南和青藏高原降水或降雪量为正（负）距平,这使得在晚春和初夏南亚的加热慢（快）,导致夏季海陆的热力对比小（大）,因而出现弱（强）夏季风。我们还发现强El Ni?o年冬季,在印度洋-亚洲上空出现类似于东太平洋-北美上空的PNA遥相关,我们称之为印度洋-亚洲遥相关型（IA）,引起亚洲冬夏季风年际变化的物理过程都是由IA遥相关型引起的。  相似文献   

NUMERICAL SIMULATION STUDY OF CLOUD INTERACTION AND FORMATION MECHANISM OF HEAVY RAIN IN MIXED CONVECTIVE-STRATIFORM CLOUD   总被引：3，自引：0，他引：3  

Hong Yanchao 《Acta Meteorologica Sinica》1998,12(1):112-128

Using the numerical model of mixed convective-stratiform clouds(MCS)in the paper(Hong1997)and the averaged stratification of torrential rain processes,the evolution processes,interaction of the two kinds of clouds,structure and the precipitation features in the MCS toproduce heavy rain are simulated and studied,and the physical reasons of producing torrential rainare analysed.The results indicate that the stratiform cloud surrounding the convective cloudbecomes weakened and dissipates in the developing and enhancing of the convective cloud,and therainfall rate and water content in the stratiform cloud increase as the distance from the convectivecloud becomes larger.The numerical experiments find out that the stratiform cloud provides abenificial developing environment for the convective cloud,i.e.,the saturated environment and theconvergence field in the stratiform cloud help to lengthen the life cycle of the convective cloud,produce sustained rainfall with high intensity and intermittent precipitation with ultra-highintensity.These and the ice phase microphysical processes are the main factors for the torrentialrain formation and the MCS is a very effective precipitation system.  相似文献   

Holocene History of the Chocó Rain Forest from Laguna Piusbi, Southern Pacific Lowlands of Colombia     

Hermann Behling  Henry Hooghiemstra  Alvaro José Negret 《Quaternary Research》1998,50(3):300-308

A high-resolution pollen record from a 5-m-long sediment core from the closed-lake basin Laguna Piusbi in the southern Colombian Pacific lowlands of Chocó, dated by 11 AMS¹⁴C dates that range from ca. 7670 to 220¹⁴C yr B.P., represents the first Holocene record from the Chocó rain forest area. The interval between 7600 and 6100¹⁴C yr B.P. (500–265 cm), composed of sandy clays that accumulated during the initial phase of lake formation, is almost barren of pollen. Fungal spores and the presence of herbs and disturbance taxa suggest the basin was at least temporarily inundated and the vegetation was open. The closed lake basin might have formed during an earthquake, probably about 4400¹⁴C yr B.P. From the interval of about 6000¹⁴C yr B.P. onwards, 200 different pollen and spore types were identified in the core, illustrating a diverse floristic composition of the local rain forest. Main taxa are Moraceae/Urticaceae,Cecropia,Melastomataceae/Combretaceae,Acalypha, Alchornea,Fabaceae,Mimosa, Piper, Protium, Sloanea, Euterpe/Geonoma, Socratea,andWettinia.Little change took place during that time interval. Compared to the pollen records from the rain forests of the Colombian Amazon basin and adjacent savannas, the Chocó rain forest ecosystem has been very stable during the late Holocene. Paleoindians probably lived there at least since 3460¹⁴C yr B.P. Evidence of agricultural activity, shown by cultivation ofZea maissurrounding the lake, spans the last 1710 yr. Past and present very moist climate and little human influence are important factors in maintaining the stable ecosystem and high biodiversity of the Chocó rain forest.  相似文献   

显生宙全球气候变化与生物绝灭事件的联系   总被引：3，自引：1，他引：3  

陈旭  布科  阮亦萍  斯科梯司  樊隽轩 《地学前缘》1997,(Z2)

根据显生宙各地质时期全球气候敏感沉积物和生物地理单元数据库，显生宙（寒武纪至中新世）可识别出２４次全球范围内不同级别的气候变化事件。有些事件与全球生物事件有着密切的联系，而不少则并无重要联系，即使这两种事件发生的时间和规模上存在着明显的一致性，也并不一定就存在着因果关系。这２４次事件根据二者的一致性和不一致性，可归纳为两类：（１）早寒武世末（一致）；（２）晚寒武世末（不一致）；（３）早奥陶世末（Ｉｂｅｘｉａｎ末，不一致）；（４）奥陶纪末（一致）；（５）志留纪兰多维列世（不一致）；（６）志留纪文洛克世早期（不一致）；（７）志留纪文洛克世末（不一致）；（８）志留纪罗德洛世末（不一致）；（９）志留纪普利道里世末（不一致）；（１０）早泥盆世埃姆斯期初（不一致）；（１１）中泥盆世艾菲尔期末（一致）；（１２）中泥盆世吉维特期末（一致）；（１３）晚泥盆世弗拉斯期末（一致）；（１４）泥盆纪末（不一致）；（１５）早石炭世末（一致）；（１６）晚石炭世维斯发期末（一致）；（１７）早二叠世萨克马尔晚期（一致）；（１８）二叠纪末（一致）；（１９）早三叠世（一致）；（２０）中—晚三叠世（不一致）；（２１）早侏罗世赫塘期（不一致）；（２?  相似文献   

Rapid change in nitrate and sulfate concentrations observed in early stage of precipitation and their deposition processes     

Hiroaki Minoura  Yasunobu Iwasaka 《Journal of Atmospheric Chemistry》1996,24(1):39-55

The concentrations of H⁺, nitrate (NO₃ ^-), and sulfate (SO₄ ^2-) in rainwater and their temporal changes were analyzed on the basis of continuous observation from 1 July 1991 to 30 June 1992 at a suburb of Nagoya, Japan. The yearly average for pH was 4.4. In general, an increasing pH with increase in precipitation amount was observed for rain events. Relatively high pH rainwater was sometimes observed at the beginning of rainfall, even though high concentrations of NO₃ ^- and SO₄ ^2- were involved. The high pH values were considered to be caused by the neutralization process with particulate matter containing cations. The yearly averaged ratio of equivalent concentration of nitrate to sulfate (N/S) in rainwater was 0.58. In the early stage of rain, the N/S value was usually more than 1.0 due to the difference of scavenging process between NO₃ ^- and SO₄ ^2-. High values of N/S ranging from 5 to 10 were found under the atmospheric conditions of calm winds and low humidity, during which it is possible that atmospheric particles float for a long time in the air before a rain event. The adsorption of NO₃ ^- in the early stage of rainfall by particulate matter was suggested from the difference in scavenging processes of NO₃ ^- and SO₄ ^2-. A possible scavenging process, called limb cloud scavenging, is presented to explain the interaction of particles and nitrate ions at the early stage of rain. In limb cloud scavenging, the repeated migration of cloud particles or raindrops between the inside and outside of clouds increases the absorption of ions to a highly condensed level, thus increasing the N/S value of rainwater. The influence of global scale seasonal phenomena with large amounts of particulates, such as typhoons or Asian dust storms, was also studied.  相似文献   

陕西地方暴雨增强数值预报系统及其试验结果分析     

杨红强  陈玉春 《高原气象》1996,15(1):77-83

该文介绍了陕西地方暴雨增数值预业务系统，并对１９９５年６－８月进行的降水准业务预报试验结果作了分析及Ｔｓ评分检验。结果表明：模式系统运行４８ｈ以上性能稳定，对陕西区域暴雨的预报效果较好，对日常业务预报有参考价值。  相似文献   

Nonlinear estimation of spatial distribution of rainfall — An indicator cokriging approach     

D-J Seo 《Stochastic Environmental Research and Risk Assessment (SERRA)》1996,10(2):127-150

Indicator cokriging (Journel 1983) is examined as a tool for real-time estimation of rainfall from rain gage measurements. The approach proposed in this work obviates real-time estimation of real-time statistics of rainfall by using ensemble or climatological statistics exclusively, and reduces computational requirements attendant to indicator cokriging by employing only a few auxiliary cutoffs in estimation of conditional probabilities. Due to unavailability of suitable rain gage measurements, hourly radar rain fall data were used for both indicator covariance estimation and a comparative evaluation. Preliminary results suggest that the indicator cokriging approach is clearly superior to its ordinary kriging counterpart, whereas the indicator kriging approach is not. The improvement is most significant in estimation of light rainfall, but drops off significantly for heavy rainfall. The lack of predictability in spatial estimation of heavy rainfall is borne out in the integral scale of indicator correlation: peaking to its maximum for cutoffs near the median, indicator correlation scale becomes increasingly smaller for larger cutoffs of rainfall depth. A derived-distribution analysis, based on the assumption that radar rainfall is a linear sum of ground-truth and a random error, suggests that, at low cutoffs, indicator correlation scale of ground-truth can significantly differ from that of radar rainfall, and points toward inclusion of rainfall intermittency, for example, within the framework proposed in this work.  相似文献   

新疆水土流失对农牧业的危害及防治对策     

胡卫忠 《地质灾害与环境保护》1996,7(3):30-36

新疆山地坡残积层分布广泛，平 原第四系堆积发育；降集中于山地，夏季暴雨频发；暴雨隔雪洪流往往造成严重水土流失。水土流失对农业造成的直接经济损 失，表现在土以力下降，农徼业减产减产减收。  相似文献