Classification and mechanism of spring and summer floods in northern Xinjiang from 2006 to 2011

The significant socioeconomic impact of extreme flooding provides an incentive to improve our understanding of flood drivers. In this study, floods that occurred in northern Xinjiang from 2006 to 2011 were divided into three categories: rainstorm-type, warming-type, and mixed-type. These three types of floods primarily occurred from April to July, with most occurring in May and June. Through analysis of the atmospheric circulation evolution process of the three types of floods, it can be concluded that when a rainstorm-type flood occurs, northern Xinjiang is affected by an anomalous cyclone that forms in front of the strengthened trough over northern Europe. Anomalous cyclones provide favorable conditions for precipitation, which is conducive to rainstorm-type floods. As for the warming-type flood event, northern Xinjiang is affected by an anomalous anticyclone formed by the eastward movement of the blocking system in the middle of the Eurasian continent. Before the third type of mixed flood event occurred, northern Xinjiang was affected by an anomalous cyclone formed by energy propagation along the northwesterly wind belt. In addition, the energy propagating along the westerly wind belt along the southern road is conducive to the formation of a high-pressure ridge in southern Xinjiang. In addition, the analysis of temperature conditions indicates that the daily maximum temperature showed a warming trend from 5 to 1 day before the warming-type and mixed-type flood event occurred. These results provide valuable insights for flood risk management by identifying atmospheric circulation patterns and temperature conditions associated with floods in northern Xinjiang.