Notice of RetractionPeriodicity of drought is decreasing in Gansu Province, China

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

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Five hundred years of drought data were analyzed for Gansu Province in China. Using wavelet transform on a large scale, we identified that droughts occur in a periodic way. The lasting time of both aridity and humidity statuses are reducing, namely the periodicities are decreasing. Over the past five hundred years, the lasting time of drought shortened from 121 years to 74 years in recent centuries, and the lasting time of humidity-state shortened to from 84 years to 12 years. A smaller periodicity (~25 years) is also decaying at a rate of two years per 100 years. The results indicate that drought disasters will afflict Gansu more frequently in the future.