FIGURE 2-9 Annual cycle of precipitation (mm day−1) in continental regions particularly affected by the deforestation of Amazonia (red), Central Africa (green), and Southeast Asia (blue). The blue curves represent the mean monthly precipitation before massive deforestation started in tropical regions (i.e., the “control” case). The red curves indicate the corresponding precipitation following tropical deforestation. The size and location of the color-coded areas corresponding to the deforested regions are at scale. Color-coded ellipses indicate the regions in which tropical forest (in green on the 1-km resolution land-cover map used for the background) was replaced with a mixture of shrubs and grassland. SOURCE: Avissar and Werth (2005).

alters the sensible and latent heat released into the atmosphere and the associated change of pressure distribution modifies the zones of atmospheric convergence and divergence, which shift the typical pattern of the Polar Jet Stream and the precipitation that it engenders.

Radiative forcing by aerosols has also been associated with teleconnected responses in distant locations. For example, a GCM simulation by Chung and Ramanathan (2003) shows that absorbing aerosols over South Asia and the North Indian Ocean can cause subsidence motions over most of the tropics, which would have a drying effect (Figure 2-10).



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