The connection between baroclinic Rossby wave packets in the upper troposphere and regional-scale heavy precipitation over Fujian-Jiangxi region in the late spring-early summer of 2006

The most serious heavy precipitation in the past 43 years (1979-2021) occurred over Fujian-Jiangxi region from late May to early June of 2006, causing significant economic losses. Using the daily precipitation collected at 2479 surface meteorological stations in China and ERA5 reanalysis database, the present study investigates the relationship between the heavy precipitation over Fujian-Jiangxi region in late spring-early summer of 2006 and baroclinic Rossby wave packets in the upper troposphere. Information flow between the two systems has been diagnosed. Results indicate that the disturbance source for this heavy precipitation originated from areas near the Syrian Desert to the north of the Arabian Peninsula and propagated along the northwest-southeast direction, reaching Fujian-Jiangxi region four days later. This kind of baroclinic Rossby wave packets provide the necessary energy for the occurrence and persistence of heavy precipitation. Analysis of wave activity flux vectors indicates that during the heavy precipitation period, disturbance energy was transported from the upstream westerly belt to Fujian-Jiangxi region almost every day. Obviously, there existed information transfer between the two regions, re-confirming that the upstream Rossby wave packets affect the Fujian-Jiangxi precipitation. The above results provide helpful hints for a better understanding of the mechanisms for heavy precipitation in this region and will be helpful for its effective prediction.