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Fig. 4 Evolution in time and longitude of the differences (wet minus dry) in intraseasonal composites
(defined by minima (wet) and maxima (dry) in filtered surface heat fluxes averaged over a 12.5-17.5N,
2.5W-2.5E subdomain), averaged between 12.5 and 17.5N. a Meridional wind at 925 hPa (shaded;
ms
-1
) and cold cloud coverage at a threshold of -40 C (contour; %). b Estimated surface heating (shaded;
influence soil moisture and vegetation, which in turn affect the partition of surface heat and
moisture fluxes into the atmosphere. If the large-scale circulation is sensitive to surface
fluxes, and the surface responds to climate anomalies with sufficient amplitude and spatial
coherence, conditions for feedback may be met. Monsoon circulations potentially provide
these conditions, driven by gradients in ocean and land surface fluxes, with the transport of
oceanic moisture into the continent being sensitive to land surface conditions.
Taylor (
2008
) demonstrated that intraseasonal feedbacks can occur between soil
moisture and rainfall in monsoon regions such as West Africa (Fig.
4
). Increases in soil
moisture associated with a wet spell induce a cool high pressure anomaly, favouring
