Flood estimation and flood management have traditionally been the domain of hydrologists, water resources engineers and statisticians, and disciplinary approaches abound. Dominant views have been shaped; one example is the catchment perspective: floods are formed and influenced by the interaction of local, catchment-specific characteristics, such as meteorology, topography and geology. These traditional views have been beneficial, but they have a narrow framing. In this paper we contrast traditional views with broader perspectives that are emerging from an improved understanding of the climatic context of floods. We come to the following conclusions: (1) extending the traditional system boundaries (local catchment, recent decades, hydrological/hydraulic processes) opens up exciting possibilities for better understanding and improved tools for flood risk assessment and management. (2) Statistical approaches in flood estimation need to be complemented by the search for the causal mechanisms and dominant processes in the atmosphere, catchment and river system that leave their fingerprints on flood characteristics. (3) Natural climate variability leads to time-varying flood characteristics, and this variation may be partially quantifiable and predictable, with the perspective of dynamic, climate-informed flood risk management. (4) Efforts are needed to fully account for factors that contribute to changes in all three risk components (hazard, exposure, vulnerability) and to better understand the interactions between society and floods. (5) Given the global scale and societal importance, we call for the organization of an international multidisciplinary collaboration and data-sharing initiative to further understand the links between climate and flooding and to advance flood research.

In this study, spatial and temporal patterns of changes in extreme events of temperature and precipitation at 143 weather stations in ten Asia‐Pacific Network (APN) countries and their associations with changes in climate means are examined for the 1955–2007 period. Averaged over the APN region, annual frequency of cool nights (days) has decreased by 6.4 days/decade (3.3 days/decade), whereas the frequency of warm nights (days) has increased by 5.4 days/decade (3.9 days/decade). The change rates in the annual frequency of warm nights (days) over the last 20 years (1988–2007) have exceeded those over the full 1955–2007 period by a factor of 1.8 (3.4). Seasonally, the frequencies of summer warm nights and days are changing more rapidly per unit change in mean temperatures than the corresponding frequencies for cool nights and days. However, normalization of the extreme and mean series shows that the rate of changes in extreme temperature events are generally less than that of mean temperatures, except for winter cold nights which are changing as rapidly as the winter mean minimum temperature. These results indicate that there have been seasonally and diurnally asymmetric changes in extreme temperature events relative to recent increases in temperature means in the APN region.There are no systematic, regional trends over the study period in total precipitation, or in the frequency and duration of extreme precipitation events. Statistically significant trends in extreme precipitation events are observed at fewer than 30% of all weather stations, with no spatially coherent pattern of change, whereas statistically significant changes in extreme temperature events have occurred at more than 70% of all weather stations, forming strongly coherent spatial patterns. Copyright © 2009 Royal Meteorological Society

A new method is presented for the extraction of mixed layer depth and entrainment zone thickness from lidar, backscatter ratio profiles. The method is based on fitting a four parameter, idealized profile to observed profiles. Optimization of the fit yields values for mixed layer depth and entrainment zone thickness. Since the fitting procedure is based on the entire measured profile, it has a robustness not found in methods based on critical backscatter or backscatter gradient. The method is tested by application to four measured profiles and three synthetic profiles. The sets of profiles include some that are very demanding because of small mixed layer to upper layer backscatter ratio contrasts, or have plumes of high backscatter imbedded in mixed and upper layers. It is shown that the method is robust and simple to implement, even for a sequence of independent profiles. Abstract A new method is presented for the extraction of mixed layer depth and entrainment zone thickness from lidar, backscatter ratio profiles. The method is based on fitting a four parameter, idealized profile to observed profiles. Optimization of the fit yields values for mixed layer depth and entrainment zone thickness. Since the fitting procedure is based on the entire measured profile, it has a robustness not found in methods based on critical backscatter or backscatter gradient. The method is tested by application to four measured profiles and three synthetic profiles. The sets of profiles include some that are very demanding because of small mixed layer to upper layer backscatter ratio contrasts, or have plumes of high backscatter imbedded in mixed and upper layers. It is shown that the method is robust and simple to implement, even for a sequence of independent profiles.

Using 6‐year data collected in a high‐resolution network of 19 stations in the province of Alicante (Spain), the characteristics of sea breezes for the period 2000–2005 were studied. This study attempts to develop a multi‐year climatology of sea breeze flows focusing on a Western Mediterranean coastal site. We used half‐hourly meteorological records from a reference station in Alicante and sea surface temperature measurements at Albufereta beach to identify past sea breeze episodes, on the basis of an objective selection technique. A total of 475 sea breeze events during the 6‐year period were identified and the following parameters were determined: mean time of onset, mean wind speed and direction at the time of onset, mean time of cessation, mean temporal dimension (duration), mean maximum velocity, mean time of maximum velocity and mean wind path of the sea breeze. The mean onset and cessation times are 0940 UTC and 2009 UTC (local standard time = UTC + 0100 h, or + 0200 h with daylight‐saving time), respectively, with a mean duration of 1029 h. The mean wind speed at the time of the passage of sea breeze fronts is low (2.07 m s⁻¹), but sea breeze gust intensities range from 3.6 to 11.6 m s⁻¹ and they generally occur during 1200–1300 UTC. Southerly and southeasterly onset flows dominate in winter, whereas more easterly onsets occur in spring and summer. The mean inland directed wind path of the sea breezes is 97.7 km with noteworthy differences throughout the year; a case study showed onshore wind peaks of 11.1 m s⁻¹, 50‐km inland of the Vinalopó river valley in the late afternoon. The spatial and temporal change in wind speed and direction were also analysed, using multi‐year wind hodographs for the 19 stations and eight well‐defined synoptic patterns favouring the development of sea breezes. Copyright © 2009 Royal Meteorological Society

We analyse the anomalously warm summer months in the Mediterranean region using the 850 hPa temperature, T850, extracted from the ERA-40 reanalysis, in order to find how these anomalies are related to the anomaly of the jet stream over the Euro-Atlantic area. In this region, the westerly jet has two main branches: the Scandinavian jet and the Mediterranean jet, which, in summer, are at a meridional minimum distance. In addition, we analyse the heat waves in the Central Mediterranean in the last half century using the temperature observations collected at fifty surface stations distributed throughout the Italian peninsula and its two major islands, and we relate these events to the position of the Mediterranean jet. We find that, when these two jets are almost aligned, there is a streak of the Mediterranean jet over the Alps and, to the south of them, an anticyclonic vorticity aloft, which forces a strong subsidence and an adiabatic warming of the troposphere over the Mediterranean. This configuration is also a characteristic of anomalously warm spells over the basin. While, when the Mediterranean jet resides further south and along the northern rim of Africa, its meridional distance from the Scandinavian jet is relatively large, the vorticity over the Mediterranean is cyclonic and this region is relatively cool. The tropospheric temperature difference between these two configurations (Mediterranean jet over the Alps and jet over North Africa) is of the order of 3 °C. Since the correlation between the observed temperatures over Italy and the ERA-40 T850 in the Central Mediterranean is more than 90%, and more than 60% in the T850 of the entire Mediterranean basin, we conclude that the heat waves over Italy are representative of exceptionally warm episodes over the Central Mediterranean, and that a warm spell over Italy is a country-scale symptom of warm spells in the Mediterranean basin. Copyright © 2006 Royal Meteorological Society.