Abstract:
The effects of Intraseasonal Oscillation on four precipitation processes in Yunnan in the spring of 2019 were studied, based on precipitation data from 125 meteorological stations in Yunnan, NCEP/NCAR reanalysis data, and Australian multivariable real-time Madden-Julian Oscillation (MJO) index. The results show that: ① When the strong MJO event phase is located in the third and fourth phases, it is beneficial to the spring precipitation in Yunnan, which affected two obvious precipitation processes in spring 2019. ② The low frequency system near the Bay of Bengal moves northward and brings the convective system or water vapor from the tropical area to Yunnan, which was related to two significant precipitation processes in Yunnan in the spring of 2019. ③ The low frequency system in the middle and high latitudes moves southward, which can bring the cold air in the middle and high latitudes to Yunnan. The strongest precipitation in Yunnan in the spring of 2019 was caused by the combination of the cold air in the middle and high latitudes and fairly good water vapor conditions.