Summer drought in northern China

The summer drought in northern China is not only influenced by sea-surface temperature (SST) variability on the the ENSO timescale (3-7 years), but also on the QBO and decadal-interdecadal tiemscales. These timescales are found through a Singular Value Decomposition analysis between the summer rainfall over China and SST anomalies for past five decades. Possible atmospheric sources linking to the drought in northern China are also studied. It is found that the variabilities on the QBO and decadal timescales are closely related to zonally-banded Asian monsoon variability, while the variation on the ENSO , which also includes a QBO component, and the interdecadal timescales are closely related to the variability of a massive geopotential height anomaly centered over Mongolia on 500-hPa, which is also shown in 850-hPa horizontal wind anomaly. This intensive Mongolia geopotential height anomaly also controls a large portion of northern China, causing persistent drought there in recent years. When the drought phase on the interdecadal timescales is exacerbated by shorter-timescale variabilities such as the 1997/98 ENSO and recent QBO, the drought becomes disastrous.