Moisture origin as a driver of temporal variabilities of the water vapour isotopic composition in the Lena River Delta, Siberia
Moisture origin as a driver of temporal variabilities of the water vapour isotopic composition in the Lena River Delta, Siberia
复制标题
DOI：
10.5194/acp-2019-942
复制
发表时间：
2020-01
影响因子：
6.3
通讯作者：
J. Bonne;H. Meyer;M. Behrens;J. Boike;S. Kipfstuhl;B. Rabe;T. Schmidt;Lutz Schönicke;H. Steen‐Larsen;M. Werner
中科院分区：
文献类型：
--
作者：
J. Bonne;H. Meyer;M. Behrens;J. Boike;S. Kipfstuhl;B. Rabe;T. Schmidt;Lutz Schönicke;H. Steen‐Larsen;M. Werner
抽象的。在北极放大影响区域大气水文循环的气候变化的背景下，至关重要的是确定北极目前的水分来源。由于水稳定同位素在相变过程中具有不同的分子特征，同位素组成是加深我们对水循环驱动因素的理解的重要工具。这项研究介绍了自2015年7月以来在东西伯利亚列纳三角洲萨莫约夫岛研究站进行的连续两年的水汽和降水同位素观测。水汽同位素信号主要受季节和天气时间尺度的变化影响。水汽同位素信号的日变化被天气变化所掩盖，表明冬季、夏季和秋季本地源的振幅在日尺度上的变化很小。春季低幅度的日变化可能表明大气和被雪覆盖的表面之间的水分交换。基于半拉格朗日反向轨迹的水汽来源诊断表明，不同的气团来源对Lena三角洲地区的水汽收支的贡献是不同的。在季节尺度上，从净水汽来源到到达地点的距离变化很大。在最冷的月份，没有观测到局地二次蒸发的贡献。在天气时间尺度上，冷季期间水汽同位素组成的变化与水汽来源区域和大气输送的变化密切相关：富含同位素的暖湿空气与来自大西洋部门的快速输送有关，而具有同位素贫乏水分的干空气和冷空气通常与在欧亚大陆北部缓慢移动的气团有关。
Abstract. In the context of the Arctic amplification of climate change affecting the regional atmospheric hydrological cycle, it is crucial to characterize the present-day moisture sources of the Arctic. The isotopic composition is an important tool to enhance our understanding of the drivers of the hydrological cycle due to the different molecular characteristics of water stable isotopes during phase change. This study introduces 2 years of continuous in situ water vapour and precipitation isotopic observations conducted since July 2015 in the eastern Siberian Lena delta at the research station on Samoylov Island. The vapour isotopic signals are dominated by variations at seasonal and synoptic timescales. Diurnal variations of the vapour isotopic signals are masked by synoptic variations, indicating low variations of the amplitude of local sources at the diurnal scale in winter, summer and autumn. Low-amplitude diurnal variations in spring may indicate exchange of moisture between the atmosphere and the snow-covered surface. Moisture source diagnostics based on semi-Lagrangian backward trajectories reveal that different air mass origins have contrasting contributions to the moisture budget of the Lena delta region. At the seasonal scale, the distance from the net moisture sources to the arrival site strongly varies. During the coldest months, no contribution from local secondary evaporation is observed. Variations of the vapour isotopic composition during the cold season on the synoptic timescale are strongly related to moisture source regions and variations in atmospheric transport: warm and isotopically enriched moist air is linked to fast transport from the Atlantic sector, while dry and cold air with isotopically depleted moisture is generally associated with air masses moving slowly over northern Eurasia.