北美洲降水中稳定同位素的时空分布以及与ENSO的关系  

Temporal-Spatial Distribution of Stable Isotopes in Precipitation and Its Relationship with ENSO over the North America

作　　者：章新平[1] 杨大庆 刘晶淼[3] 

机构地区：[1]湖南师范大学资源与环境科学学院 [2]Water and Environmental Research Center, University of Alaska, Fairbanks 99775-5860, USA [3]中国气象科学研究院

出　　处：《冰川冻土》2006年第1期29-36,共8页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(40271025);湖南省教育厅研究项目(03C210)资助

摘　　要：分析了北美洲降水中δ18O的时空分布特征以及与温度、降水量、ENSO的关系.结果表明:无论是在陆地还是在海洋,北美降水中平均δ18O的纬向分布是非常显著的.随着纬度的升高,降水中δ18O迅速减小.整个北美大陆均存在温度效应,并随纬度的增加而加强.不同季节温度效应分布的差异仅表现在其范围和强度的变化上.降水量效应主要出现在低纬度海洋、中低纬度太平洋的东海岸和湾流的西北海岸.在内陆区,降水量效应不存在.不同季节降水量效应分布的差异也仅表现在其范围和强度的变化上.在大陆内部和高纬度地区,对应显著的温度效应,δ18O的季节差异Δδ18O具有较大的正值;在低纬度海洋,对应显著的降水量效应,Δδ18O较小或为负值;在相同的纬度,陆地上的Δδ18O明显大于海洋.代表大陆性特征的渥太华站和代表海洋性特征的中途岛站降水中δ18O与Ni o-4的SST具有显著的正相关关系,其中,尤以5月的δ18O与Ni o-4的SST的连续相关关系最显著,表明ENSO事件的强信号对该时期陆地和海洋降水中稳定同位素的变化具有重要影响.The characteristics of temporal-spatial distribution of δ^18O in precipitation and its relationships with temperature, precipitation amount and ENSO were analyzed in this study. The analyses show that the latitudinal distribution of the mean δ^18O in precipitation is very remarkable in the North America, regardless over lands or oceans. The mean δ^18O differences between continent and ocean are less besides high latitudes. With increasing latitude, the δ^18O in precipitation decreases quickly. It is found that the temperature effect appears over the whole North America continent, and becomes much more marked with increasing latitude. The variations of extension and intensity characterize a distributional difference of temperature effect on different seasons. The amount effect happens mainly in low-latitude oceans, cast coast of the low-middle-latitude Pacific Ocean and northwest coast of Gulf Stream. However, no amount effect in inland. Similarly, the variations of extension and intensity characterize also a distributional difference of amount effect on different seasons. In inland and high latitudes of the North America, the △δ^18O displays greater positive value corresponding to the distinct temperature effect; in lowlatitude oceans, it does smaller or a negative value; and in the same latitudes, △δ^18O in land is markedly greater than that in ocean. Furthermore, there are distinct positive correlations between SST in Nin-4 and δ^18O in precipitation at Ottawa and Midway Island that stand for continental and oceanic situations respectively, in which, the continuous correlations between the precipitation δ^18O in May and SST in Nino-4 are remarkable, showing that the strong signal form ENSO has important impact on the variations of stable isotopes in precipitation of the land and the ocean in this period.

关 键 词：稳定同位素 温度效应 降水量效应 ENSO 北美 

分 类 号：P426.612[天文地球—大气科学及气象学]