Out-of-Phase Relationship between Boreal Spring and Summer Decadal Rainfall Changes in Southern China

• Published in: Journal of climate Vol. 27; no. 3; pp. 1083 - 1099
• Main Authors: Zhu, Zhiwei, Li, Tim, He, Jinhai
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.02.2014
• Subjects: Anomalies; Boreal age; Climate change; Convection; Convection cooling; Cooling; Datasets; Earth, ocean, space; East Asian monsoon; El Nino; El Nino phenomena; Empirical analysis; Exact sciences and technology; Experiments; External geophysics; General circulation models; Hadley circulation; La Nina; Meteorology; Monsoon trough; Monsoons; Oceanic convection; Oceans; Orthogonal functions; Precipitation; Rain; Rainfall; Rainfall anomalies; Sea surface; Sea surface temperature anomalies; Seasons; Spring; Spring (season); Summer; Summer circulation; Water in the atmosphere (humidity, clouds, evaporation, precipitation); Wind; Southern China; Far East; Asia; China; East Asia; Yangtze River; China, People's Rep; rainfall; General circulation models; atmospheric precipitation; Summer; Empirical orthogonal function; East Asia; multivariate analysis; 1990-2000; Spring(season); 2000-2010; Reanalysis; atmospheric circulation; Seasonal teleconnection; 1980-1990
• ISSN: 0894-8755; 1520-0442
• DOI: 10.1175/JCLI-D-13-00180.1

A multivariate empirical orthogonal function (MV-EOF) analysis for 1979–2010 shows that low-level circulation and rainfall over East Asia experienced a significant decadal shift around the mid-1990s. During boreal spring (March–May), the first principal component (PC) of the MV-EOF exhibits a marked decadal change around the mid-1990s, while during boreal summer (June–August) the second PC shows a pronounced decadal shift around the same time. It is further noted that the decadal rainfall change over southern China experienced an out-of-phase relationship between boreal spring and summer; that is, from the pre-1994 to the post-1994 period, the rainfall tends to decrease in boreal spring but increase in boreal summer. A mechanism is put forward to explain the out-of-phase decadal rainfall change over southern China between boreal spring and summer. In boreal spring, the composite differences of SST between the latter and former decadal periods indicate a La Niña–like pattern with warming in the western Pacific and cooling in the eastern Pacific. This pattern leads the enhanced convection over the Maritime Continent, which may further induce anomalous subsidence and thus negative rainfall anomalies over southern China through the local Hadley circulation. In boreal summer, dominant decadal SST warming appears in the entire tropical Indian Ocean while the negative SST anomalies in eastern Pacific are much weaker. The warm SST anomaly over the Indian Ocean leads to suppressed convection over the Maritime Continent, which, through the local Hadley cell, favors the strengthening the East Asian monsoon trough and leads to a positive rainfall anomaly over southern China.