Observed positive vegetation-rainfall feedbacks in the Sahel dominated by a moisture recycling mechanism. Issue 1 (December 2017)

• Record Type: Journal Article
• Authors: Yu, Yan; Notaro, Michael; Wang, Fuyao; Mao, Jiafu; Shi, Xiaoying; Wei, Yaxing
• Is Part Of: Nature communications. Volume 8:Issue 1(2017)
• Page Start: 1
• Page End: 9
• Publication Date: 2017-12
• Subjects: Biology -- Periodicals; Physical sciences -- Periodicals; 505
• DOI: 10.1038/s41467-017-02021-1
• Languages: English
• ISSNs: 2041-1723

Abstract

Abstract Classic, model-based theory of land-atmosphere interactions across the Sahel promote positive vegetation-rainfall feedbacks dominated by surface albedo mechanism. However, neither the proposed positive vegetation-rainfall feedback nor its underlying albedo mechanism has been convincingly demonstrated using observational data. Here, we present observational evidence for the region's proposed positive vegetation-rainfall feedback on the seasonal to interannual time scale, and find that it is associated with a moisture recycling mechanism, rather than the classic albedo-based mechanism. Positive anomalies of remotely sensed vegetation greenness across the Sahel during the late and post-monsoon periods favor enhanced evapotranspiration, precipitable water, convective activity and rainfall, indicative of amplified moisture recycling. The identified modest low-level cooling and anomalous atmospheric subsidence in response to positive vegetation greenness anomalies are counter to the responses expected through the classic vegetation-albedo feedback mechanism. The observational analysis further reveals enhanced dust emissions in response to diminished Sahel vegetation growth, potentially contributing to the positive vegetation-rainfall feedback. Vegetation-rainfall feedbacks in the Sahel are thought to be positive, but the precise mechanisms for this are unclear. Here the authors analyse observations to show that a moisture recycling mechanism drives this feedback.