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Extreme Precipitation (extreme + precipitation)
Selected AbstractsExtreme precipitation over Southeastern Brazil in the austral summer and relations with the Southern Hemisphere annular modeATMOSPHERIC SCIENCE LETTERS, Issue 1 2010Fernanda Cerqueira Vasconcellos Abstract Southeastern Brazil is a highly industrialized and populated region which largely contributes to the country's economy. Extreme precipitation over this region can cause floods and landslides occurrences or lack of precipitation that can affect many sectors of economy. The objective of this work is to identify atmospheric characteristics associated with austral summer extreme precipitation over part of Southeastern Brazil. The atmospheric characteristics obtained from wet and dry composites suggest that extreme precipitation was associated with anomalous circulation over the region, forced by a PSA-like wavetrain intensified by the Southern Annular Mode. Copyright © 2010 Royal Meteorological Society [source] The annual cycle of heavy precipitation across the United Kingdom: a model based on extreme value statisticsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2009D. Maraun Abstract The annual cycle of extreme 1-day precipitation events across the UK is investigated by developing a statistical model and fitting it to data from 689 rain gauges. A generalized extreme-value distribution (GEV) is fit to the time series of monthly maxima, across all months of the year simultaneously, by approximating the annual cycles of the location and scale parameters by harmonic functions, while keeping the shape parameter constant throughout the year. We average the shape parameter of neighbouring rain gauges to decrease parameter uncertainties, and also interpolate values of all model parameters to give complete coverage of the UK. The model reveals distinct spatial patterns for the estimated parameters. The annual mean of the location and scale parameter is highly correlated with orography. The annual cycle of the location parameter is strong in the northwest UK (peaking in late autumn or winter) and in East Anglia (where it peaks in late summer), and low in the Midlands. The annual cycle of the scale parameter exhibits a similar pattern with strongest amplitudes in East Anglia. The spatial patterns of the annual cycle phase suggest that they are linked to the dominance of frontal precipitation for generating extreme precipitation in the west and convective precipitation in the southeast of the UK. The shape parameter shows a gradient from positive values in the east to negative values in some areas of the west. We also estimate 10-year and 100-year return levels at each rain gauge, and interpolated across the UK. Copyright © 2008 Royal Meteorological Society [source] Trends in daily precipitation and temperature extremes across western Germany in the second half of the 20th centuryINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 9 2005Yeshewatesfa Hundecha Abstract The evolution of daily extreme precipitation and temperature from 1958 to 2001 was investigated within the German side of the Rhine basin. Trends of a set of extreme precipitation and temperature indices defined on daily time series of precipitation and temperature were calculated at 611 precipitation and 232 temperature stations located within the study area and their corresponding significances were tested using the non-parametric Kendall- tau test. The results obtained indicated that both the daily minimum and maximum extreme temperatures have increased over the investigation period, with the degree of change showing seasonal variability. On an annual basis, the change in the daily minimum extreme temperature was found to be greater than that of the daily maximum extreme temperature. The daily extreme heavy precipitation has shown increasing trends both in magnitude and frequency of occurrence in all seasons except summer, where it showed the opposite trend. The station values of the daily precipitation were also interpolated on a regular grid of 5 km × 5 km so that the changes in the indices could be investigated on areal precipitation by aggregating the interpolated precipitation to any desired scale. This enables assessment of the hydrological consequences of the changes in the extreme precipitation. Although the spatial pattern remained more or less similar with that of the point-scale trends for all indices, the average trend magnitude showed an increase with the scale of the area on which precipitation was aggregated. Copyright © 2005 Royal Meteorological Society [source] Trends in extreme daily rainfall across the South Pacific and relationship to the South Pacific Convergence ZoneINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 8 2003G. M. Griffiths Abstract Daily rainfall records from 22 high-quality stations located in the South Pacific were analysed, over the common period 1961,2000, in order to assess whether extreme rainfall events have altered in their frequency or magnitude. A comprehensive spatial coverage across the South Pacific was provided, analysing a range of indices of extreme precipitation, which reflect both high rainfall events and drought. Clear spatial patterns emerged in the trends of extreme rainfall indices, with a major discontinuity across the diagonal section of the South Pacific Convergence Zone (SPCZ). Stations located between 180 and 155°W exhibit a greater number of significant abrupt changes in extreme climate than elsewhere in the South Pacific, and the majority of climatic jumps occur in the 1970s or 1980s (coincident with a displacement northeastward of the diagonal part of the SPCZ and a large local increase in mean annual temperature). Notably, all significant abrupt changes in an extreme rainfall intensity index occurred in the late 1970s or early 1980s, and in every case the index showed an increase in extremity following the change point, regardless of station location. For the stations located south of the SPCZ, this may also be linked to the observed warming since the 1970s. Significant abrupt changes in mean precipitation were also identified around the mid 1940s, for two longer, century-scale records, which again correspond to a major displacement of the diagonal section of the SPCZ. An indicator of the diagonal SPCZ position is significantly temporally correlated with an extreme rainfall intensity index, at two locations either side of the diagonal section of the SPCZ, at decadal time scales or longer. This suggests that the displacement of the diagonal portion of the SPCZ on decadal time scales influences not only mean precipitation, but also daily rainfall extremes. Copyright © 2003 Royal Meteorological Society [source] Assessing future changes in extreme precipitation over Britain using regional climate model integrationsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2001P.D. Jones Abstract In a changing climate it is important to understand how all components of the climate system may change. For many impact sectors, particularly those relating to flooding and water resources, changes in precipitation intensity and amount are much more important than changes in temperature. This study assesses possible changes in extreme precipitation intensities estimated through both quantile and return period analysis over Britain. Results using a regional climate model (with greenhouse gas changes following the IS92a scenario for 2080,2100) indicate dramatic increases in the heaviest precipitation events over Britain. The results provide information to alter design storm intensities to take future climate change into account, for structures/projects that have long life times. Copyright © 2001 Royal Meteorological Society [source] Sources of water vapour contributing to the Elbe flood in August 2002,A tagging study in a mesoscale modelTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 638 2009H. Sodemann Abstract In this study we investigate the contribution of various moisture sources to the Elbe flood that occurred in Central Europe during August 2002. An 8-day simulation with the mesoscale numerical weather prediction model CHRM, including newly implemented water vapour tracers, has been performed. According to the simulation, rather than drawing moisture from one single dominant source region, water vapour from widely separated moisture sources contributed to the extreme precipitation in the most affected area, notably at distinct, subsequent periods of time, and each in significant amounts. These moisture sources include the Atlantic and Mediterranean ocean areas inside the model domain, evapotranspiration from land areas, and long-range advection from subtropical areas outside the model domain. The results highlight the importance of the concurrent upper-level circulation and the mesoscale flow structures associated with the cyclone for producing extreme precipitation in parts of Germany, Austria, and the Czech Republic during that period. Furthermore, the numerical and technical problems of implementing water vapour tracers into a limited-area model are discussed, including conservative tracer advection, initialization, boundary treatment, and the handling of precipitation parametrizations. An evaluation of the consistency of the method in terms of water vapour, cloud water, and precipitation is provided, with generally satisfying results. The model with its detailed water vapour tracer implementation can now be used for further case-studies and climatological simulations, and serve as a reference for evaluating the performance of other moisture tracking methods, such as those based on backward trajectories. Copyright © 2009 Royal Meteorological Society [source] Extreme precipitation over Southeastern Brazil in the austral summer and relations with the Southern Hemisphere annular modeATMOSPHERIC SCIENCE LETTERS, Issue 1 2010Fernanda Cerqueira Vasconcellos Abstract Southeastern Brazil is a highly industrialized and populated region which largely contributes to the country's economy. Extreme precipitation over this region can cause floods and landslides occurrences or lack of precipitation that can affect many sectors of economy. The objective of this work is to identify atmospheric characteristics associated with austral summer extreme precipitation over part of Southeastern Brazil. The atmospheric characteristics obtained from wet and dry composites suggest that extreme precipitation was associated with anomalous circulation over the region, forced by a PSA-like wavetrain intensified by the Southern Annular Mode. Copyright © 2010 Royal Meteorological Society [source] Uncertainties in future projections of extreme precipitation in the Indian monsoon regionATMOSPHERIC SCIENCE LETTERS, Issue 3 2009A. G. Turner Abstract Uncertainties in changes to the spatial distribution and magnitude of the heaviest extremes of daily monsoon rainfall over India are assessed in the doubled CO2 climate change scenarios in the IPCC Fourth Assessment Report. Results show diverse changes to the spatial pattern of the 95th and 99th subseasonal percentiles, which are strongly tied to the mean precipitation change during boreal summer. In some models, the projected increase in heaviest rainfall over India at CO2 doubling is entirely predictable based upon the surface warming and the Clausius,Clapeyron relation, a result which may depend upon the choice of convection scheme. Copyright © 2009 Royal Meteorological Society and Crown Copyright [source] | ||||||||||