关键词: 降水异常, 能量输送, 扰动动能, 角动量

Abstract: Based on precipitation observation information and NCEP reanalysis data during 1981-2018, the causes of abnormal precipitation in spring sowing period in northern Hubei Province were analyzed by using synthetic diagnostics and atmospheric energy spectrum methods. The results show that in abnormally less precipitation years, the subtropical high was weaker and its position was southerly, and the polar vortex was weaker too. The perturbation kinetic energy over mid-latitude was weak in meridional direction, while the zonal transfer position was southerly, and the angular momentum transferred obviously to the south, the energy exchange between north and south was weak. Thus the intersection of cold and warm air was not obvious over the north of Hubei, and it was divergent in the lower troposphere, which was not conducive to the frontogenesis. In abnormally more precipitation years, both the subtropical high and polar vortex were stronger, the plateau trough was more actively. The perturbation kinetic energy over mid-latitude was stronger in meridional direction, while the zonal transfer position was northerly，the angular momentum transferred obviously and the energy exchanged frequently between the south and north. Thus the intersection of cold and warm air was obvious over the north of Hubei, it was convergence in the lower troposphere, which was conducive to the frontogenesis.

Key words: precipitation anomalies, energy transfer, perturbation kinetic energy, angular momentum