Extended Abstract

4. Sensitivity experiment results1) PrecipitationRainfall precipitation from sensitivity experiments indicate that during the 24-hintegration the intensity and range of rainfall are enhanced with the increase of terrain, themaxima in Lu Mountains are respectively 264, 271, 279 and 285 mm for T0.0, T0.5, CONand T1.5 experiment. From the 24 to 48-h integration (Fig.2a-c), the heavy rainfall mainlymoves to Da-bie Mountains and terrain modulated the rainfall obviously. The higher theterrain is, the rainfall distribution is more uneven. Comparison of the T0.5, CON and T1.5displays heavy rainfall can be blocked to the upslope of Da-bie Mountains, where the amountof rainfall center enhance from 436 to 660 mm with the increase of terrain. It is notable thatterrain has minor impact on the total rain band distribution, the rainfall reinforcedsignificantly even when Da-bie terrain is removed. In other word, in this case, there has norelationship between the occurrence of rainfall reinforcement and Da-bie Mountains. Theterrain just strengthens the intensity of rainfall reinforcement and makes the rainfalldistribution uneven. Moreover, Da-bie Mountains always situate in the northeast azimuth ofTalim, warm and wet southeast flow from Talim maintain vapor and energy transfer tomountainous region, which are favorable for rainfall increase. Specifically, the intensity ofrainfall center with Da-bie Mountains is larger about 15% than that without topography.2) Topography impact analysisa) Convergent line and meso-scale vortex(a)(b)Fig.3. The difference of stream and divergence with terrain (dashed line) at 900 hPa between CON and T0.0 at (a)0000 UTC 3 Sep and (b)1200 UTC 3 Sep 2005To highlight the topography effect, figure 3 shows the difference wind field at 900hPa(CON minus T0.0). On 1800 UTC 2 Sep,a meso-scale convergent line between northwardflow and southward flow is formed in the Mountains. After 6-h, the convergent movesouthward slowly and its convergence is larger than 3×10 -4 s -1 (Fig.3a). Interestingly, ameso-β vortex develops in the convergent line and intensifies, consequently, a strong-45-