Rob Allan

TL;DR: In this paper, the authors examined historical patterns of climatic variables over the Indian Ocean basin in the global context and found that the quasi-decadal signal alone can provide an important modulation of Indian Ocean climatic patterns.

TL;DR: In this paper, the authors examined evidence for both protracted El Ninino and La Ninfia phases of the last 30-odd years of the 1990s and concluded that these phases are associated with a variety of causes, ranging from an enhanced greenhouse effect to volcanic dust to a major change in the earth's climate system.

Abstract: Rainfall variability occurs over a wide range of temporal scales. Knowledge and understanding of such variability can lead to improved risk management practices in agricultural and other industries. Analyses of temporal patterns in 100 yr of observed monthly global sea surface temperature and sea level pressure data show that the single most important cause of explainable, terrestrial rainfall variability resides within the El Nino-Southern Oscillation (ENSO) frequency domain (2.5-8.0 yr), followed by a slightly weaker but highly significant decadal signal (9-13 yr), with some evidence of lesser but significant rainfall variability at interclecadal time scales (15-18 yr). Most of the rainfall variability significantly linked to frequencies tower than ENSO occurs in the Australasian region, with smaller effects in North and South America, central and southern Africa, and western Europe. While low-frequency (LF) signals at a decadal frequency are dominant, the variability evident was ENSO-like in all the frequency domains considered. The extent to which such LF variability is (i) predictable and (ii) either part of the overall ENSO variability or caused by independent processes remains an as yet unanswered question. Further progress can only be made through mechanistic studies using a variety of models.

TL;DR: In this article, the authors compare observed sea level pressure trends with those simulated in response to natural and anthropogenic influence in a suite of eight up-to-date coupled general circulation models.

TL;DR: Methods of benchmarking and assessing multiple products to aid inter-comparison and end-user product selection are described, and creation of multiple methodologically independent products is recommended for quantifying uncertainty.