热带气旋外围环流影响下深圳高温的定量估算

Quantitative Estimation of High Temperature Under the Influence of Outer Circulation of Tropical Cyclones in Shenzhen

利用NCEP再分析资料提供的风、湿度、垂直速度等资料及深圳地面观测数据,分析热带气旋外围环流造成深圳高温的原因。基于热力学能量方程,估算各因子的增温率和增温比例。结果表明:非绝热加热项是深圳高温的热量基础,增温比例为90.2%,平均增温率为0.83℃·h^(-1),假设8:00-14:00时增温率不变,计算出平均情况下,非绝热加热项使14时温度比08时增加5.0℃。其次湿度减小引起的增温、气流下沉增温、暖平流是深圳出现高温的重要因素,各自的增温比例分别为7.6%、3.8%、7.0%,总的增温率为0.17℃·h^(-1),计算出平均情况下,这3项可使14时温度比08时增加1.12℃。即热带气旋外围环流影响下,非绝热加热项对增温贡献最大,其中由于空气相对湿度小,定压比热减小,增温贡献较大;空气干绝热下沉增温使局地温度升高,但贡献较小;暖平流使局地温度的升高,贡献较大。

Based on the NCEP reanalysis data of wind, humidity, vertical velocity and the surface observation data of Shenzhen, the main warming factors are explored under the influence of peripheral circulation of tropical cyclones. According to thermodynamic energy equation, the contribution rate of every warming factor is estimated. Results are indicated as follows： Non-adiabatic term is the basis of high temperature in Shenzhen; the warming proportion is 90.2% ; and the warming rate is0.83 ℃· h-1. If assuming the war- ming rate unchanged from 08：00 to 14：00, then temperature would increase by 5.0℃ from 08：00 to 14：00 caused by the non-adiabatic term. The second important reason for high-temperature includes the decrease of relative humidity, air sinking warming, and warm advection. Their respective proportions are 7.6%, 3.8% and 7.0%, with a total of warming rate of 0. 17 ℃·h-1. Temperature increases 1. 12℃ from 08：00 to 14：00 caused by these 3 terms. Therefore the greatest contribution to high temperature is made by the non-adiabatic term including decrease of relative humidity. Smaller contribution is made by dry air adiabatic subsidence. Larger contribution is made by warm advection.