| Abstract | dc.description.abstract | Twenty-first century climate model projections show an amplification of
the annual cycle in tropical precipitation with increased strength in both wet and dry
seasons, but uncertainty is large and few studies have examined transition seasons.
Here we analyze coupled climate model projections of global land monsoons and
show a redistribution of precipitation from spring to summer in northern (North
America, West Africa and Southeast Asia) and southern (South America, Southern
Africa) regions. The annual cycle changes are global in scale. Two mechanisms,
remote (based on tropospheric stability) and local (based on low level and surface
moisture), are evaluated through the annual cycle. Increases in tropospheric stability
persist from winter into spring and are reinforced by a reduction in surface moisture
conditions, suggesting that in spring both remote and local mechanisms act to inhibit
convection. This enhanced spring convective barrier leads to reduced early season
rainfall; however, once sufficient increases in moisture (by transport) are achieved,
decreases in tropospheric stability result in increased precipitation during the late
rainy season. Further examination of this mechanism is needed in observations and
models, as the projected changes would have substantial implications for agriculture,
water management, and disaster preparedness. | es_CL |
