• Spring rainfall;
  • Inner Mongolia;
  • frontal cyclones;
  • classification;
  • synoptic conditions


Spring (March to May) is a crucial season for crop seeding and grass growth in Inner Mongolia (IM), China. Yearly harvests of agriculture, and animal husbandry, are controlled partially by spring precipitation. Based on the observations at 104 stations in IM, the spring precipitation during 1961–2010 was investigated and analysed. The results show that the amount of spring precipitation displays a trend associated with an increasing frequency of effective spring precipitation events (ESPE, with more than 10 stations among all observatories with over 10 mm daily precipitation). In addition, the synoptic conditions of the 141 ESPEs were studied through analysis of the sea level pressure (SLP), and 850, 700 and 500 hPa charts. They were classified into five types and named for the source positions of the frontal cyclones over the Eurasian continent on the SLP chart. Most of the Hetao, Mongolian and Huanghe cyclones in spring time, in general, bring strong wind, decreasing temperature or dust storms to IM. Sometimes they may also cause effective precipitation when the moisture transportation is favourable along the cyclone paths. The Northeast China cyclone mainly influences Northeast China and can lead to rainfall with adequate moisture supplies. In most cases, cold air from Siberia forms a frontal cyclone or a trough around Lake Baikal, and then heads eastward or southeastward, producing precipitation over large areas in IM in spring. Typical features of the synoptic evolutions of those five types are summarized and presented through analysis of representative ESPEs. Copyright © 2012 Royal Meteorological Society