论文部分内容阅读
1999年盛夏中昆仑山北坡大多数河流出现了有正式水文记录以来的最大洪峰,各河流最大洪峰出现时间存在不一致性,洪峰变化复杂.应用主要河流出山口水文站的逐日流量和降水量,和田气象站的逐日0℃层高度,500 hPa气温以及NCEP/NCAR 500 hPa高度场资料,分析了1999年夏季中昆仑山北坡诸河出现的历史特大洪水特性及其气象成因.这次特大洪水是高空持续高温引起的冰雪融水与产流区出现的暴雨共同作用下的混合型洪水.洪水前期春季到初夏该区域山区降水偏多,高空气温和0℃层高度持续偏低,对高山区的积雪积累极为有利;7月底至8月初和田高空气温和0℃层高度迅速上升并维持数日,使冰雪快速消融,同时山区出现大降水是引发洪水的直接气象成因.在青藏高原东部柴达木盆地上空存在有500 hPa稳定高压,使中亚副热带大槽东移中昆仑山北坡是这次特大洪水发生的环流系统特点.
Most of the rivers in the northern Kunlun Mountains in the mid-summer of 1999 appeared the biggest flood peak since the official hydrological records, and the maximum peak appearance time of each river was inconsistent and the flood peak changed in a complicated way. By applying the daily flow and precipitation of the main river outflow station hydrological station, The daily 0 ℃ layer height, the temperature of 500 hPa and the NCEP / NCAR 500 hPa geopotential height field data of Wada weather stations were used to analyze the historical flood characteristics and their meteorological causes that occurred in the northern rivers in the Kunlun Mountains in the summer of 1999. The flood It is a mixed flood under the interaction of ice and snowmelt caused by continuous high temperature and rainstorm occurring in the runoff area.Previous flood to early summer flood in this area mountainous area is more than normal, Of the accumulation of snow is extremely favorable; from late July to early August high temperature and high temperature 0 ℃ layer height rose rapidly and maintain a few days, the rapid melting of snow and ice, while the occurrence of heavy rainfall in mountain areas is the direct cause of the meteorological flood in the eastern part of the Tibetan Plateau There is a steady high pressure of 500 hPa over the Damu Basin so that the northward shift of the Central Asian Subtropical Large Channel in the Kunlun Mountains is the circulation of this extraordinary flood System features.