A 1‐year longδ18O record of water vapor in Niamey (Niger) reveals insightful atmospheric processes at different timescales
A 1‐year longδ18O record of water vapor in Niamey (Niger) reveals insightful atmospheric processes at different timescales
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DOI：
10.1029/2012gl051298
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发表时间：
2012-04
影响因子：
5.2
通讯作者：
G. Tremoy;F. Vimeux;Salla Mayaki;Ide Souley;O. Cattani;C. Risi;G. Favreau;Monique Oi
中科院分区：
文献类型：
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作者：
G. Tremoy;F. Vimeux;Salla Mayaki;Ide Souley;O. Cattani;C. Risi;G. Favreau;Monique Oi
我们使用波长扫描腔衰荡光谱 (WS-CRDS) 呈现了尼亚美（尼日尔）长达 1 年的代表性水蒸气 δ18O 记录 (δ18Ov)。我们探索局部和区域大气过程如何影响从季节到昼夜尺度的 δ18Ov 变化。在季节尺度上，δ18Ove呈现W形，这与季风期间区域对流活动的增加以及旱季期间尼亚美以北大规模沉降的加剧有关。在季风季节，δ18Ov 记录了 25-40 天和 15-25 天波段的广泛季节内模态，这些模态可能与众所周知的西非季风 (WAM) 模态相关。冬季，在天气尺度（5-9 天）也可以看到强烈的 δ18Ov 调制，这是由热带-温带遥相关通过斜斜波列状结构的传播和来自较高海拔和纬度的空气侵入所驱动的。δ18Ov 调制揭示了一个重要的昼夜循环，反映了旱季期间边界层和自由大气之间的混合过程，并记录了 季风季节与中尺度对流系统相关的密度流的传播。
We present a 1‐year long representativeδ18O record of water vapor (δ18Ov) in Niamey (Niger) using the Wavelength Scanned‐Cavity Ring Down Spectroscopy (WS‐CRDS). We explore how local and regional atmospheric processes influenceδ18Ov variability from seasonal to diurnal scale. At seasonal scale, δ18Ovexhibits a W‐shape, associated with the increase of regional convective activity during the monsoon and the intensification of large scale subsidence North of Niamey during the dry season. During the monsoon season,δ18Ovrecords a broad range of intra‐seasonal modes in the 25–40‐day and 15–25‐day bands that could be related to the well‐known modes of the West African Monsoon (WAM). Strongδ18Ovmodulations are also seen at the synoptic scale (5–9 days) during winter, driven by tropical‐extra‐tropical teleconnections through the propagation of a baroclinic wave train‐like structure and intrusion of air originating from higher altitude and latitude.δ18Ovalso reveals a significant diurnal cycle, which reflects mixing process between the boundary layer and the free atmosphere during the dry season, and records the propagation of density currents associated with meso‐scale convective systems during the monsoon season.