Numerical Simulation of Atmospheric Duct in Typhoon Subsidence Area

图  1  WRF模拟区域嵌套示意图

(黑点为2002年8月31日20：00南京及周围地区出现波导的探空站点，虚线连接的空白圆圈为台风鹿莎的移动路径，间隔为12 h，起止时间为8月30日00：00—9月1日00：00)

Fig. 1  WRF modeling domains

(the black dots indicate duct-occurred stations in Nanjing and its neighboring area at 2000 BT 31 August 2002; the empty circles linked by dash line indicate the typhoon track from 0000 BT 30 August to 0000 BT 1 September in 2002; the interval between two neighboring circles is 12 h)

图  2  FNL再分析数据850 hPa位势高度场 (单位：gpm) 与风场 (全风速杆为4 m·s^-1)

(实心圆与空心圆分别为出现与未出现大气波导的探空站点)

Fig. 2  The potential heights (unit:gpm) and winds (a full barb indicates 4 m·s^-1) analysis of FNL data at 850 hPa

(solid circles and empty circles indicate the stations with and without duct, respectively)

图  3  控制试验模拟的南京站大气波导的演变

(实线为模拟值，虚线为观测值)

Fig. 3  Evolution of the simulated modified refractivity at Nanjing Station

(the solid line represents the simulated one; the dashed line represents the observed one)

图  4  控制试验模拟的大气波导分布

(实心圆与空心圆分别为出现与未出现大气波导的探空站点)

Fig. 4  Distribution of the simulated duct by the control experiment

(solid circles and empty circles indicate the stations with and without duct, respectively)

图  5  控制试验模拟的温度和大气波导沿图 1中线段AB的垂直剖面

(填充色为温度, 单位：℃; 蓝色实线、虚线、点线分别代表0，-80，-160 M·km^-1的大气修正折射指数垂直梯度；箭头代表风矢量；黑点代表南京站位置)

Fig. 5  Vertical sections of the simulated temperature and duct along AB shown in Fig. 1

(colorful shaded represents temperature, unit:℃; blue solid, dashed and dotted lines represent the vertical gradient of modified refractivity with value 0, -80, -160 M·km^-1, respectively; the arrows represent wind, the black dot on the horizontal axis represents the location of Nanjing Station)

图  6  南京上空不同高度气块12 h后向追踪轨迹 (a) 和后向追踪中气块高度 (b)、温度 (c) 随时间的变化以及南京地区局地温度 (d) 的时间变化

(AO, BO, CO, DO与EO为不同高度气块的移动路径，O为南京站位置)

Fig. 6  The 12 h backward trajectory of air mass at different heights from Nanjing (a) and temporal changes of heights (b) and temperatures (c) of backward trajectories, and local temperature (d) at Nanjing Station

(AO, BO, CO, DO and EO indicate the trajectorys of the air mass from different heights, respectively; O indicates the location of Nanjing Station)

图  7  控制试验与敏感性试验模拟的温度沿图 1中线段CD的垂直剖面

(黑点代表南京站位置)

Fig. 7  Vertical sections of the simulated temperature of control and sensitivty experiments along CD in Fig. 1

(the black dot indicates the location of Nanjing Station)

图  8  同图 5，但为水汽混合比 (填充色，单位：g·kg^-1)

Fig. 8  Same as in Fig. 5, except for water mixing ratio (colorful shaded, unit: g·kg^-1)

图  9  4个台风个例FNL再分析数据850 hPa位势高度场与波导区域

(空心台风符号为台风路径，实心台风符号代表波导发生时刻台风的位置，实心圆为发生波导的探空站点)

Fig. 9  FNL analysis at 850 hPa and duct areas of four typhoon cases

(hollow typhoon symbol indicates the track of typhoon, solid typhoon symbol indicates the location of the typhoon when ducts occurred, and solid circles indicate duct-occurred stations)

图  10  海上波导与水汽混合比的垂直梯度沿图 1中线段EF的垂直剖面

(填充色为水汽混合比的梯度; 蓝色实线、虚线、点线分别代表0，-80，-160 M·km^-1的大气修正折射指数垂直梯度；箭头为风场)

Fig. 10  Vertical gradient sections of water mixing ratio and duct along EF in Fig.1

(colorful shaded is the vertical gradient of water mixing ratio; blue solid, dashed and dotted lines represent the vertical gradient of modified refractivity with value 0, -80, -160 M·km^-1, respectively; arrows represent wind)