THE IMPACT OF EL NINO ON AN ENSEMBLE OF EXTENDED-RANGE FORECASTS
MONTHLY WEATHER REVIEW 115:9 (1987) 2103-2117
Influence of the Atlantic, Pacific and Indian Oceans on sahel rainfall
Nature 322:6076 (1986) 251-253
Abstract:
Folland et al.1 have reported that persistently dry and wet periods of several years in the Sahel have been accompanied by global-scale patterns of sea-surface temperature (SST) anomaly. They also demonstrated that the response of a general circulation model (GCM) of the atmosphere to an observed composite SST difference field between a number of such dry and wet periods showed substantial reduction in Sahel rainfall compared with values from a simulation with climatological SSTs. I examine here the same model's response to the individual components of the composite SST difference field in the Atlantic, Pacific and Indian Oceans. It is found that over the western Sahel, the Atlantic and Pacific fields have a comparable effect in reducing rainfall whereas the Indian Ocean field produces a slight enhancement. Results suggest that, over the eastern Sahel, the Indian Ocean has the dominant role in reducing rainfall. © 1986 Nature Publishing Group.Sahel rainfall and worldwide sea temperatures, 1901-85
Nature 320:6063 (1986) 602-607
Abstract:
Using the comprehensively quality-controlled Meteorological Office Historical Sea Surface Temperature data set (MOHSST)1,2 we show for the first time that persistently wet and dry periods in the Sahel region of Africa are strongly related to contrasting patterns of sea-surface temperature (SST) anomalies on a near-global scale. The anomalies include relative changes in SST between the hemispheres, on timescales of years to tens of years, which are most pronounced in the Atlantic. Experiments with an 11-level global atmospheric general circulation model (AGCM) support the idea that the worldwide SST anomalies modulate summer Sahel rainfall through changes in tropical atmospheric circulation3-6. El Nino events may also play a part. We do not discount the effects of soil moisture and albedo changes in the Sahel7,8, although Courel et al.9 have questioned the importance of albedo changes, but we do suggest that worldwide SST anomalies may have a more fundamental influence on Sahel rainfall. © 1986 Nature Publishing Group.A possible relationship between some 'severe' winters in North America and enhanced convective activity over the tropical West Pacific.
Monthly Weather Review 114:3 (1986) 648-651
Abstract:
From observations and a variety of general circulation modeling evidence, it is suggested that the exceptionally cold weather experienced over much of the US during some recent winter months (eg January 1985, December 1976-February 1977) was associated with enhanced latent heat release over the tropical West Pacific. The mechanism associated with such enhancement may not be unique.- AuthorsA study of wintertime circulation anomalies during past El Niño events using a high resolution general circulation model. I: Influence of model climatology
Quarterly Journal of the Royal Meteorological Society 112:473 (1986) 613-638