关键词: 中美玉米带, 气候背景, SPEI, 时空分布, 成因分析

Abstract: Corn growth in China and the United States(US) has been seriously affected by the drought disaster under climate change. In order to effectively reference the advanced experiences on drought mitigation of the US, the standardized precipitation evapotranspiration index(SPEI) was calculated for two corn belts located in Northeast of China(NEC) and the US based on the observed meteorological data during 1986-2015. The observed differences in drought characteristics were compared and their causes were further analyzed by conducting the linear fitting analysis, correlation test and other statistical methods. The results showed that, compared with the US, corn growth period in the corn belt of NEC has higher solar radiation, lower average air temperature, and less but concentrated precipitation during late growth stage, and precipitation in the corn belt of the US was relatively evenly distributed during the whole growth period. Time variation of annual SPEI, drought frequency, drought severity and drought extent during different growth stages were significant different in two areas, with respective characteristics in the spatial distribution. Drought frequency and severity in the corn belt of NEC was higher than that of the US during the whole growth period because of the higher frequency of high air temperature, rainless and high radiation weather, especially the differences of drought characteristics between two areas became more significant during late growth stage due to the lower frequency of abnormal weather happened in the corn belt of the US. Consistency of temporal changes of radiation, air temperature and precipitation in two areas led to the similar trends of dry-wet variations, i.e., wetter during early and drier during late growth stage. However, significant wetter trend was only happened in the corn belt of the US during early growth stage due to its significant increase in precipitation and decrease in radiation. The US may pay more attention to the drought management during early growth stage of the corn belt in respond to drought threats, but for NEC, in addition to the drought management during early growth stage, additional attention should be paid to the late growth stage. Therefore, in referencing the experience of drought mitigation from foreign countries, enough attention should be paid to the differences of drought-resistant measures resulted from the differences in the characteristics and disaster-leading factors of drought disaster in the different regions.

Key words: Corn belts of NEC and the US, Climate background, SPEI, Spatiotemporal distribution, Cause analysis