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Publication Date
30 November 2017

Observed Positive Vegetation-Rainfall Feedbacks in the Sahel Dominated by a Moisture Recycling Mechanism



Classic, model-based theory of land-atmosphere interactions across the Sahel promoted 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, although it is associated with a moisture recycling mechanism, rather than the classic albedo-based mechanism, on the seasonal to interannual time scale. 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.

“Observed Positive Vegetation-Rainfall Feedbacks In The Sahel Dominated By A Moisture Recycling Mechanism”. 2017. Nature Communications 8: 1873. doi:10.1038/s41467-017-02021-1.
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