The role of the Sahara Low in summertime Sahel rainfall variability and change in the CMIP3 models
نویسندگان
چکیده
Projections for 21 century changes in summertime Sahel precipitation differ greatly across models in the CMIP3 dataset, and cannot be explained solely in terms of discrepancies in the projected anomalies in global SST. This study shows that an index describing the low-level circulation in the north Atlantic-African region, namely the strength of the low-level Saharan Low, correlates with Sahel rainfall in all models and at the timescales of both interannual/interdecadal natural variability, and of the forced centennial trend. An analysis of Sahel interannual variability provides evidence that variations in the Sahara Low can be a cause, not just a consequence, of variations in Sahel rainfall and suggests that a better understanding of the sources of model discrepancy in Sahel rainfall predictions might be gained from an analysis of the mechanisms influencing changes in the Sahara Low.
منابع مشابه
Forced Sahel rainfall trends in the CMIP5 archive
The simulations of the fifth Coupled Models Intercomparison Project (CMIP5) strengthen previous assessments of a substantial role of anthropogenic emissions in driving precipitation changes in the Sahel, the semi-arid region at the southern edge of the Sahara. Historical simulations can capture the magnitude of the centennial Sahel drying over the span of the 20th century and confirm that anthr...
متن کاملOn the decadal scale correlation between African dust and Sahel rainfall: The role of Saharan heat low–forced winds
A large body of work has shown that year-to-year variations in North African dust emission are inversely proportional to previous-year monsoon rainfall in the Sahel, implying that African dust emission is highly sensitive to vegetation changes in this narrow transitional zone. However, such a theory is not supported by field observations or modeling studies, as both suggest that interannual var...
متن کاملDrought in the African Sahel: variability, change and agency
Tyndall working papers are "work in progress". Whilst they are commented on by Tyndall researchers, they have not been subject to a full peer review. The accuracy of this work and the conclusions reached are the responsibility of the author(s) alone and not the Tyndall Centre. Summary The African Sahel experienced a prolonged dry episode in the latter decades of the twentieth century, character...
متن کاملSST Forcings and Sahel Rainfall Variability in Simulations of the Twentieth and Twenty-First Centuries
The outlook for Sahel precipitation in coupled simulations of the twenty-first century is very uncertain, with different models disagreeing even on the sign of the trends. Such disagreement is especially surprising in light of the robust response of the same coupled models to the twentieth-century forcings. This study presents a statistical analysis of the preindustrial, twentieth-century and t...
متن کاملSST forcings and Sahel rainfall variability in simulations of the 20th and 21st centuries
The outlook for Sahel precipitation in coupled simulations of the 21 century is very uncertain, with different models disagreeing even on the sign of the trends. Such disagreement is especially surprising in light of the robust response of the same coupled models to the 20 century forcings. We present a statistical analysis of the pre-industrial, 20 century and 21 century A1B scenario simulatio...
متن کامل