中文摘要：

利用最新的北极径流资料（R—arcticNET V3．0和ArcticRIMS），对进入北冰洋的4条主要河流的季节及年代际变化进行诊断分析。结果表明：入海径流在4—6月的大幅增加主要是由气温达到融点后积雪融化造成的，降水的作用次之。总的来说，欧亚区域在过去的70年里入海径流量是增加的，而北美区域在近30年里入海径流量是减小的，但注入北冰洋的径流总量是增大的。值得注意的是入海径流的年代际变化在不同季节增减趋势显著不同，夏季和秋季径流量减小，而其他两个季节径流量增大。进一步分析了影响入海径流变化的一些气候因子，结果表明：北大西洋涛动（北太平洋指数）与欧亚（北美）区域的冬、春季径流量存在正相关。春季气温与春季径流量呈正相关，而与夏季径流量呈负相关。降水与径流量基本上为同步正相关。春季积雪覆盖面积与春季径流量为负相关，而与夏季径流量为正相关，夏季积雪覆盖面积与夏季的径流量为正相关。

英文摘要：

Using the latest Arctic runoff data set, including R-ArcticNET V3.0 and ArcticRIMS, analyze the seasonal variation and decadal trend of four dominant rivers that flow into the Arctic. The results show that there is a sharp increase of the Arctic runoff from April to June, which is primarily due to snow melt when surface air temperature exceeds the freezing point. The contribution of the precipitation is secondary. The discharge into the Arctic from Eurasia has increased for the past 70 years, whereas the discharge from North American has decreased for the past 30 year. However, the total discharge into the Arctic has increased. More importantly, the decadal trend of the Arctic runoff is seasonally dependent. There is a downward trend in summer and autumn, and an upward trend in spring and winter. We further discuss the influence of atmospheric circulation and surface climate conditions on seasonal discharges of the four rivers. The results suggest that the North Atlantic Oscillation （North Pacific Index） has positive correlation with discharge in winter and spring from Eurasia （North American）. Surface air temperature in spring has positive （negative） relationship with discharges in spring （summer）. Precipitation and discharges show almost simultaneous in-phase relationship. Snow cover in spring has negative （positive） correlation with runoff in spring （summer）. Summer snow cover has positive relationship with summer runoff.