A STUDY ON THE VARIATION OF DROUGHT PERIODS OCCURRING IN NORTHWEST CHINA AND OTHER AFRICA-ASIA CONTINENTAL REGIONS

Characteristics of the drought periods which occurred in North Africa,Middle East,Middle Asia and Northwest China were studied based on the analysis of rainfall data from 1870-1990.It is found that the drought periods first started in North Africa and expanded eastward to Northwest China through Middle East and Middle Asia in about 27.5 years.And then a new teleconnection pattern of 30-50 day low-frequency oscillation which is associated with the droughts over the Africa-Asia Continent was discovered.Finally,a hypothesis is proposed based on the statistical results that the eastward expansion of drought periods may be caused by the occurrence of giant earthquakes(Ms6.0) which have a tendency to shift eastward from North Africa to Northwest China in about 27.75 years.