阿拉伯海超级气旋风暴“查帕拉”（2015）快速加强过程中环境场特征

Environmental Characteristics During the Rapid Intensification of Super Cyclonic Storm Chapala (2015) over the Arabian Sea

关键词:  查帕拉，快速加强，高空出流，涡度，位涡

Key words:  Chapala  rapid intensification  upper-level outflow  vorticity  potential vorticity

摘要:

利用美国联合台风警报中心(JTWC)发布的北印度洋热带气旋数据、NOAA 0.25 °×0.25 °逐日OISST资料以及ERA5提供的0.25 °×0.25 °逐小时的再分析资料分析了阿拉伯海超级气旋风暴“查帕拉”（2015）快速加强过程中的环境场特征，结果表明：较常年平均偏暖3.0~3.5 ℃的暖水区，为“查帕拉”的快速加强提供了水汽和能量条件；“查帕拉”北侧的副热带西风急流和南侧的高空出流通道的建立是其快速加强的重要高空强迫条件，高层辐散风的增强促进质量流出形成强上升运动，这也伴随着旋转风动能的快速增长；在“查帕拉”快速增强时段，高层150 hPa以上存在显著的正位涡异常，高层的正位涡异常能够调整引起低层气旋性环流加强，同时中层400 hPa有显著的正位涡平流输入，正涡度在垂直方向快速增长，300 hPa附近显著增暖，内核区的垂直对流运动达到最强。

Abstract:

Based on the best-track data from the Joint Typhoon Warning Center, ERA5 0.25?°×0.25?° reanalysis data, and NOAA 0.25?°×0.25?° daily Optimum Interpolation Sea Surface Temperature data, a study was conducted to investigate the environmental characteristics during the rapid intensification of super cyclonic storm Chapala (2015) over the Arabian Sea. The results showed that the warm pool, which was 3.0—3.5?℃ warmer than the annual average, provided water vapor and energy for the storm’s rapid intensification. The establishment of the subtropical westerly jet on the north side of Chapala and the upper-level outflow channel on the south side were important upper-level forcing conditions for its rapid intensification. The enhancement of high-level divergent wind promoted the mass outflow to form a strong upward motion, accompanied by the rapid growth of rotational wind energy. There was a significant positive potential vorticity anomaly above 150 hPa during the rapid intensification of Chapala, bringing about the strengthening of cyclonic circulation at the lower level. At the same time, there was a significant positive potential vorticity advection inflow at 400 hPa. Thus, positive vorticity increased rapidly in the vertical direction. There was a warm core near 300 hPa, with the vertical convective motion in the inner core reaching the maximum.