热带扰动是热带地区重要的天气系统,可能有机会发展为热带气旋。文章利用卫星遥感和再分析资料对比了南海能够发展和不能够发展为热带气旋的热带扰动的特征差异。结果表明:南海发展和不发展热带扰动的时空分布具有显著的区域性和季节性;发展的热带扰动具有更慢的移动速度和更长的持续时间。比较热带扰动对应的气象因子,结果显示决定南海热带扰动能否发展的关键气象因子包括:850h Pa相对涡度、垂直风切变、850h Pa与500h Pa大气温度差、向外长波辐射(OLR)和中层大气相对湿度,并且利用这些关键气象因子构建了判别南海热带扰动能否发展的预报方程。研究结果有助于提高我们对南海热带扰动发展和热带气旋生成的早期预报能力。
Tropical disturbances are part of the important weather systems in the tropical regions and have the potential to develop into tropical cyclones. In this study, the characteristics of developing and non-developing tropical disturbances over the South China Sea(SCS) were compared using satellite observations and reanalysis datasets. The results revealed that developing and non-developing tropical disturbances have significant regional and seasonal characteristics. The developing tropical disturbances have slower moving speeds and persist for a longer lifetime, compared with the non-developing tropical disturbances over the SCS. By investigating the meteorological variables for tropical disturbances over the SCS, five key environmental factors that could determine a tropical disturbance to develop or not are found, including the 850-h Pa relative vorticity, vertical wind shear, the temperature difference between 850 and 500 h Pa, the outgoing long wave radiation(OLR), and the mid-level atmospheric relative humidity. A forecasting equation has been developed based on these key meteorological factors to predict whether a tropical disturbance over the SCS will develop or not. These results can help us to better predict tropical disturbance development and tropical cyclone formation over the SCS.