Soil moisture and predicted spells of extreme temperatures in Britain

This paper reports on an analysis of the relationship of soil moisture to extreme temperatures in Britain, taken from the Hadley Centre general circulation model HadCM3 (1860-2099) and validated using the central England temperature extremes from the overlapping period 1878-2000. By 2100, HadCM3 predicts higher average temperatures and a greater variability, asymmetry, and persistence of warm extremes. A generalized extreme value analysis relates extremes to the periods of low soil moisture in the model. Longer spells of extreme temperature are seen to arise both from the statistical increase in the frequency of extremes and from the extended periods of low soil moisture. As an example, by 2060-2100 the probability of hot spells longer than 7 days with Tmax > 25°C is predicted to rise from its present value of 2%/summer to 10%/summer for high soil moisture summers and to 80%/summer when the low soil moisture summers are included

Present-day climatology and projected changes of warm and cold days in the CNRM-CM3 global climate model.

20 pagesInternational audienceThe impact of global warming on the warmest and coldest days of the annual cycle is explored according to an A2 scenario simulated by the CNRM-CM3 climate model in the framework of the IPCC AR4 intercomparison. Given the multi-model spread in IPCC projections, a validation strategy is proposed using the NCEP/NCAR reanalysis. Validation of the late twentieth century model climatology shows that warm and cold model events are slightly too long and infrequent. Although interannual trends in the warm (cold) day occurrence were positive (negative) only for six (three) of the nine considered sub-continental regions, simulated model trends are always positive (negative). This different behaviour suggests that simulated non-anthropogenic decadal variability is small relative to anthropogenic trends. Large-scale synoptic processes associated with European regional warm and cold peaks are also described and validated. Regional cold peaks are better reproduced than warm peaks, whose intensity accuracy is limited by other physical variables. Positive (negative) winter anomalies of sea and land surface temperature lead to summers with severe (weak) temperatures. These inter-annual anomalies are generated by a persistent pressure dipole over Europe. Regarding climate change, warm (cold) events will become more (less) frequent and longer (shorter). The number of warm days will largely rise and the number of cold days will dramatically decrease. The intensity of warm days will be particularly pronounced over Europe, given the projected summer drying in this region. However, according to the limited skill of the CNRM model, these results must be considered with cautio

A measurement of electron production in hadronic Z0 decays and a determination of GAMMA (Z0 --> b anti-b)

Contains fulltext : 124390.pdf (postprint version ) (Open Access

A Study of D*+- production in Z0 decays

Contains fulltext : 125111.pdf (preprint version ) (Open Access

A Global determination of alpha-s (M(z0)) at LEP

Contains fulltext : 124389.pdf (publisher's version ) (Closed access