1971—2016年河南省夏玉米生长季极端干旱时空特征

选用地表湿润指数，利用1971—2016年气象数据对河南省夏季极端干旱发生的时空特征进行了分析。结果表明：近46 a来，河南省夏季极端干旱发生频数在年均0.08～2.15月之间，总体上呈现微弱的下降趋势。6月和9月极端干旱发生次数高于7月和8月。1970s发生频数最多，2000s最少，2010s呈现回升的趋势。6月和9月极端干旱发生站次百分比明显高于7月和8月，且6、7月和9月的发生站次百分比在2010s也呈现回升趋势。各年代平均发生频数均以豫南地区最高，近46 a来极端干旱总次数呈现由南向北逐渐递减的分布特征，但6月份发生总次数高值区则主要分布在豫中和豫西地区。全省范围内极端干旱发生存在明显的4~8 a周期变化，2010s极端干旱发生频数和站次百分比均呈回升趋势，应引起夏玉米生产上的关注和重视。

Spatial and temporal characteristics of extreme drought in summer maize growing season in Henan Province during 1971-2016

The temporal and spatial characteristics of extreme droughts in summer maize growing season in Henan Province were analyzed by using surface humidity index and meteorological data from 1971 to 2016. Results showed that in past 46 years, the annual frequency of extreme drought in summer maize season in Henan ranged from 0.08 to 2.15 months, showing a weak downward trend on the whole. The number of extreme droughts in June and September was higher than that in July and August.The most frequent drought occurred in 1970s and the least were in 2000s, and was on the rise in 2010s. The percentage of extreme drought occurring stations in June and September were significantly higher than that in July and August. The value in June, July, and September showed a rising trend in 2010s. The average frequency of each year was the highest in southern regions. The total number also presented a decreasing distribution from the south to north spatially. However, the highest values in June and September were mainly distributed in northern and western areas. The occurrence of extreme droughts in the whole province had an obvious 4~8 year cycle. The frequency of extreme droughts and the percentage of occurring stations in the 2010s showed the rising trend, which should be paid attention to in summer maize production.