中文摘要：

20世纪80年代以来，海河流域经受了严重的气象性和水源性干旱；与此同时，其自然气候蒸发能力却呈现出显著的下降趋势。利用标准气象台站的历史资料，研究了该流域大气绝对湿度的演变趋势，初步的研究结果表明：海河流域大气绝对湿度呈现年代增加的趋势，尤其是每年5、6月份的农田灌溉季节，这种增加的趋势更加显著；值得指出的是，自20世纪80年代中期以来，该流域的大气绝对湿度出现一个显著跃升的现象，跃升幅度达10％左右。鉴于水汽在天气气候和水份循环中的重要作用，该流域大气绝对湿度增加原因及其气候环境效应，值得进一步关注和研究。

英文摘要：

The Haihe River basin experienced severe drought and water shortage since the 1980s; furthermore, the evaporative capacity of the natural climate cycle shows a significant downtrend. The long-term change in absolute humidity was studied using historical data from reference stations. The preliminary results indicated that absolute humidity was on the rise in the interdecadal timescale, especially during the field irrigation season in May or June, where the uptrend was more prominent. There was an obvious zooming in atmospheric absolute humidity since the middle of the 1980s and the zooming extended up to about 10%. The reasons for this and the consequences for the climate and environment warranty further study of the important role of water vapor in the weather, climate, and hydrological cycle.