Spring is the critical period for atmospheric circulation transition from winter to summer.The spring water cycle is very im-portant to agriculture in planting crop and the initial growth of crop.Note that there was a significant abrupt decadal change in the water budget increase during early spring over eastern China in the late 1970s.Studied here are the decadal variations of water budgets over the key regions and the associated change of water cycle over East Asia and atmospheric circulation over Asia-West Pacific region in early spring,using the observed(OBS) precipitation,the ECMWF(ERA) and NCEP/NCAR rea-nalysis(NRA),and the Mantua's Pacific decadal oscillation index(PDOI).The water budget increments from March to April exhibited a sharp decrease over the key region around Huaihe River basin(HHR)(111°-120°E;31°-36°N) after year 1978.Before 1977 the water vapor flux through south boundary of the HHR region increased greatly during March to April by 1.52 mm d 1 in ERA and 1.88 mm d 1 in NRA.Concurrently the moisture convergence and precipitation over the region also in-creased greatly.The increment for the moisture convergence was 1.11 mm d 1 in ERA and 1.22 mm d 1 in NRA,and for the precipitation was 1.08 mm d 1 in observation and 1.05 mm d 1 in ERA.April was the time that the water budgets over HHR increased most rapidly before 1977.But after 1978 the water budgets decreased conversely from Mach to April.The water vapor flux increment through the south boundary was 0.03 mm d 1 in ERA and 0.01 mm d 1 in NRA,the moisture conver-gence increment was 0.91 mm d 1 in ERA and 0.53 mm d 1 in NRA,and precipitation increment was 0.08 mm d 1 in ob-servation and 0.15 mm d 1 in ERA.Further investigation has shown that the large-scale atmospheric circulation in the early spring has correspondingly changed significantly after the late 1970s.During March to April,the weakening of the trough over East Asia became significantly slower,and the strengthening of the ridge over the west China became significantly faster in the
