Changes in spatiotemporal drought characteristics from 1961 to 2017 in northeastern maize-growing regions, China

A drought is a disaster that poses great threats to maize production. Thus, it is vital to study the spatiotemporal evolution of the standardized precipitation evapotranspiration index (SPEI) in the maize-growing regions in Northeast China (MGRNC). Here, we use the meteorological data of each growth stage from 1961 to 2017. This work aimed to analyze the spatiotemporal variation characteristics of the SPEI in MGRNC using the Mann–Kendall (MK) trend test, MK mutation point test, and Morlet wavelet method. The results indicated that from 1961 to 2017, the average SPEI values in Liaoning and Eastern Inner Mongolia showed a downward trend (the linear trend rates were − 0.02/10a and − 0.04/10a, respectively); however, no clear trend was observed in SPEI values in Heilongjiang and Jilin. There was a main cycle of approximately 20 a and a subcycle of approximately 7–10a for SPEI values in the whole growth stage and the sowing–seedling stage in MGRNC from 1961 to 2017, while the SPEI changes in the other three growth stages were inconsistent with the whole growth stage. The spatial distribution pattern of SPEI values decreased obviously from northeast to southwest during the whole growing stage. The drought frequencies during the different growth stages indicated that it was relatively dry at the heading–flowering stage. With the development of the growth stage, the frequency of droughts decreased significantly. The values of drought frequency and relative drought area for each sub-region in the study area occurred in the following order: Eastern Inner Mongolia > Jilin > Liaoning > Heilongjiang. The frequencies of mild to moderate droughts were 48.16