本文選題：高原低渦　切入點(diǎn)：地形降水　出處：《中國氣象科學(xué)研究院》2017年碩士論文

【摘要】：本文利用第三次青藏高原大氣科學(xué)試驗(yàn)的多種雷達(dá)、雨滴譜以及MODIS衛(wèi)星觀測資料、常規(guī)氣象站地面和高空觀測資料,針對2014年7月14日發(fā)生在青藏高原中部那曲地區(qū)的一次降水過程,研究了降水的時(shí)空變化特征,觸發(fā)不同階段降水的天氣尺度和中尺度環(huán)流系統(tǒng)以及相關(guān)的云降水物理特征,得到的主要結(jié)論如下:(1)從降水演變特征看,這次降水過程包括三個(gè)階段,即發(fā)生在下午的強(qiáng)降水階段和夜間的兩個(gè)弱降水階段。(2)從影響系統(tǒng)看,下午的降水過程主要由天氣尺度的高原低渦發(fā)展引起,此時(shí)那曲位于低渦中心前部的中尺度輻合線上,雷達(dá)回波呈現(xiàn)出向東北方向傳播的特征,隨著高原低渦的減弱,那曲第一階段降水結(jié)束;發(fā)生在晚上的降水過程主要與高原低渦前部的暖濕東南氣流爬越那曲附近的地形有關(guān),東南氣流為產(chǎn)生降水提供了有利的水汽、大氣不穩(wěn)定和淺薄的動(dòng)力抬升條件;隨著低層?xùn)|北氣流加強(qiáng),雷達(dá)回波總體上向西南方向傳播。(3)從云降水微物理特征看,高原低渦降水初期,低渦前部的上升運(yùn)動(dòng)深厚,在地面以上3~(-1)1 km高度之間的上升氣流速度超過3 m s~(-1),對流發(fā)展明顯,而在后期對流性明顯減弱,伴隨著云頂升高;東南氣流爬坡引起的地形降水以層狀云降水為主,并且層狀云上部有上升氣流存在;高原低渦降水的雨滴譜分布較寬(0.3-4.9 mm),而夜間降水過程的雨滴譜分布較窄(0.3-2.1 mm)。(4)對于引起第一個(gè)降水階段的高原低渦來說,該高原低渦的發(fā)展主要是由低層輻合的加強(qiáng)引起,而高層渦度平流和散度項(xiàng)則加強(qiáng)了反氣旋環(huán)流。
[Abstract]:In this paper, the radar, raindrop spectrum and MODIS satellite observation data of the third Qinghai-Xizang Plateau atmospheric science experiment are used, and the surface and upper air observation data of conventional weather stations are used. Based on a precipitation process in Naqu area of the central Qinghai-Tibet Plateau on July 14, 2014, the temporal and spatial variation characteristics of precipitation, the synoptic scale and mesoscale circulation system of triggering precipitation in different stages and the related physical characteristics of cloud precipitation are studied. The main conclusions obtained are as follows: (1) from the point of view of the evolution of precipitation, the precipitation process consists of three stages, that is, the heavy precipitation stage in the afternoon and the two weak precipitation stages in the night) from the perspective of the influence system. The precipitation process in the afternoon is mainly caused by the synoptic scale of the plateau vortex development. At this time, Naqu is located on the mesoscale convergence line in front of the center of the low vortex. The radar echo shows the characteristics of propagation to the northeast, and with the weakening of the plateau low vortex, The precipitation process in the evening is mainly related to the warm and wet southeastern airflow in front of the plateau vortex which climbs over the topography near Naqu, and the southeast air stream provides favorable water vapor for the precipitation. Atmospheric instability and shallow dynamic uplift conditions; with the enhancement of the lower northeast air flow, the radar echo propagates generally to the southwest.) from the microphysical characteristics of cloud precipitation, the rising motion of the front part of the low vortex precipitation in the plateau is deep in the initial stage. The updraft velocity between 3 ~ 1 km above the surface is more than 3 m ~ (-1) m ~ (-1), the convection develops obviously, but in the later stage the convection becomes weaker, accompanied by the rise of the cloud top, and the topographic precipitation caused by the southeasterly flow climbing slope is mainly stratiform cloud precipitation. And there is updraft in the upper part of stratiform cloud, the raindrop spectrum distribution of low vortex precipitation in the plateau is wider 0.3-4.9 mm ~ (-1), while that of rain drop spectrum in the process of night precipitation is narrower (0.3-2.1 mm 路m ~ (4)) for the plateau vortex which causes the first precipitation stage, The development of the low vortex in the plateau is mainly caused by the enhancement of convergence in the lower layer, while the advection and divergence of vorticity in the upper layer strengthen the anticyclonic circulation.
【學(xué)位授予單位】：中國氣象科學(xué)研究院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P458.121

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