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Storm Intensities (storm + intensity)

Distribution by Scientific Domains

Earth and Environmental Science	62%

Selected Abstracts

Effect of growing watershed imperviousness on hydrograph parameters and peak discharge

HYDROLOGICAL PROCESSES, Issue 13 2008
Huang-jia Huang
Abstract An increasing impervious area is quickly extending over the Wu-Tu watershed due to the endless demands of the people. Generally, impervious paving is a major result of urbanization and more recently has had the potential to produce more enormous flood disasters than those of the past. In this study, 40 available rainfall,runoff events were chosen to calibrate the applicable parameters of the models and to determine the relationships between the impervious surfaces and the calibrated parameters. Model inputs came from the outcomes of the block kriging method and the non-linear programming method. In the optimal process, the shuffled complex evolution method and three criteria were applied to compare the observed and simulated hydrographs. The tendencies of the variations of the parameters with their corresponding imperviousness were established through regression analysis. Ten cases were used to examine the established equations of the parameters and impervious covers. Finally, the design flood routines of various return periods were furnished through use of approaches containing a design storm, block kriging, the SCS model, and a rainfall-runoff model with established functional relationships. These simulated flood hydrographs were used to compare and understand the past, present, and future hydrological conditions of the watershed studied. In the research results, the time to peak of flood hydrographs for various storms was diminished approximately from 11 h to 6 h in different decrements, whereas peak flow increased respectively from 127 m3 s,1 to 629 m3 s,1 for different storm intensities. In addition, this study provides a design diagram for the peak flow ratio to help engineers and designers to construct hydraulic structures efficiently and prevent possible damage to human life and property. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Assessing future changes in extreme precipitation over Britain using regional climate model integrations

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2001
P.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]

Deglacial seasonal and sub-seasonal diatom record from Palmer Deep, Antarctica,

JOURNAL OF QUATERNARY SCIENCE, Issue 5 2005
Eleanor J. Maddison
Abstract The Antarctic Peninsula is one of the most sensitive regions of Antarctica to climate change. Here, ecological and cryospheric systems respond rapidly to climate fluctuations. A 4.4,m thick laminated diatom ooze deposited during the last deglaciation is examined from a marine sediment core (ODP Site 1098) recovered from Basin I, Palmer Deep, western Antarctic Peninsula. This deglacial laminated interval was deposited directly over a glaciomarine diamict, hence during a globally recognised period of rapid climate change. The ultra-high-resolution deglacial record is analysed using SEM backscattered electron imagery and secondary electron imagery. Laminated to thinly bedded orange-brown diatom ooze (near monogeneric Hyalochaete Chaetoceros spp. resting spores) alternates with blue-grey terrigenous sediments (open water diatom species). These discrete laminae are interpreted as austral spring and summer signals respectively, with negligible winter deposition. Sub-seasonal sub-laminae are observed repeatedly through the summer laminae, suggesting variations in shelf waters throughout the summer. Tidal cycles, high storm intensities and/or intrusion of Circumpolar Deep Water onto the continental shelf introduced conditions which enhanced specific species productivity through the season. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Application of SSM/I satellite data to a hurricane simulation

THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 598 2004
Shu-hua Chen
Abstract The impact of Special Sensor Microwave/Imager (SSM/I) data on simulations of hurricane Danny is assessed. The assimilation of SSM/I data is found to increase the atmospheric moisture content over the Gulf of Mexico, strengthen the low-level cyclonic circulation, shorten the model spin-up time, and significantly improve the simulation of the storm's intensity. Two different approaches for assimilating SSM/I data, namely assimilating retrieved products and assimilating raw measurements, are further compared. The data-assimilation analyses from these two approaches give different moisture distributions in both the horizontal and vertical directions in the storm's vicinity, which may potentially affect the simulated storm's development; however, the simulated storm intensities are considered comparable for the Danny case. From sensitivity tests performed in this study, it is also found that the choice of the observational error variances could be potentially important to the model simulations. Copyright © 2004 Royal Meteorological Society. [source]

Ecohydrology of a semi-arid forest: partitioning among water balance components and its implications for predicted precipitation changes

ECOHYDROLOGY, Issue 2 2010
Naama Raz Yaseef
Abstract The distribution of precipitation inputs into different hydrological components of water-limited forest ecosystems determines water availability to trees and consequently forest productivity. We constructed a complete hydrological budget of a semi-arid pine forest (285 mm annual precipitation) by directly measuring its main components: precipitation (P), soil water content, evapotranspiration (ET, eddy covariance), tree transpiration (sap flux), soil evaporation (soil chambers), and intercepted precipitation (calculated). Our results indicated that on average for the 4-year study period, ET accounted for 94% of P, varying between 100% when P < 250 mm and 85% when P > 300 mm (with indications for losses to subsurface flow and soil moisture storage in wetter years). Direct measurements of the components of the ET flux demonstrated that both transpiration and soil evaporation were significant in this dry forest (45% and 36% of ET, respectively). Comparison between ecosystem ET (eddy covariance measurements) and the sum of its measured components showed good agreement on annual scales, but up to 30% discrepancies (in both directions) on shorter timescales. The pulsed storm pattern, characteristics of semi-arid climates, was sufficient to maintain the topsoil layer wet during the whole wet season. Only less often and intensive storms resulted in infiltration to the root zone, increasing water availability for uptake by deeper roots. Our results indicate that climate change predictions that link reduced precipitation with increased storm intensity may have a smaller effect on water availability to forest ecosystems than reduced precipitation alone, which could help forests' survival and maintain productivity even under drier conditions. Copyright © 2009 John Wiley & Sons, Ltd. [source]

The impact of storm events on solute exports from a glaciated forested watershed in western New York, USA

HYDROLOGICAL PROCESSES, Issue 16 2006
S. P. Inamdar
Abstract This study analysed the importance of precipitation events from May 2003 to April 2004 on surface water chemistry and solute export from a 696 ha glaciated forested watershed in western New York State, USA. The specific objectives of the study were to determine: (a) the temporal patterns of solutes within individual storm events; (b) the impact of precipitation events on seasonal and annual export budgets; and (c) how solute concentrations and loads varied for precipitation events among seasons as functions of storm intensity and antecedent moisture conditions. Analysis of solute trajectories showed that NH4+, total Al and dissolved organic nitrogen (DON) peaked on the hydrograph rising limb, whereas dissolved organic carbon (DOC) concentrations peaked following the discharge peak. Sulphate and base-cations displayed a dilution pattern with a minimum around peak discharge. End-member mixing analysis showed that throughfall contributions were highest on the rising limb, whereas valley-bottom riparian waters peaked following the discharge peak. The trajectories of NO3, concentrations varied with season, indicating the influence of biotic processes on the generation, and hence flux, of this solute. Storm events had the greatest impact on the annual budgets for NH4+, K+, total dissolved Al, DON and DOC. Storm events during summer had the greatest impact on seasonal solute budgets. Summer events had the highest hourly discharges and high concentrations of solutes. However, NO3, and DOC exports during a spring snowmelt event were considerably more than those observed for large events during other periods of the year. Comparisons among storms showed that season, precipitation amount, and antecedent moisture conditions affected solute concentrations and loads. Concentrations of solutes were elevated for storms that occurred after dry antecedent conditions. Seven of the largest storms accounted for only 15% of the annual discharge, but were responsible for 34%, 19%, 64%, 13%, 39% and 24% of the annual exports of NH4+, K+, Al, NO3,, DON and DOC respectively. These results suggest that the intense and infrequent storms predicted for future climate-change scenarios will likely increase the exports of solutes like DOC, DON, NH4+, Al and K+ from watersheds. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Wind speed measurements and forest damage in Canton Zurich (Central Europe) from 1891 to winter 2007

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2010
Tilo Usbeck
Abstract The most severe damage to forests in central Europe occurs during winter storms that are caused by Northern Hemispheric mid-latitude cyclones. These winter storms have caused several catastrophic windthrows during the past four decades. Amounts of forest storm damage are believed to be a function of both the size of the forest and the storm intensity. To test this hypothesis, the Zurich region (city and canton) was chosen because long-term climate observation data is available for the region. The relationships between forest attributes, wind speed and forest damage were explored by comparing data on forests and wind speed from 107 winters with forest damage. Storm damage was defined as the proportion of damaged forests with respect to the growing stock. The variables: daily wind run (91 years), daily maximum hourly average wind speed (107 years) and peak gust wind speed (74 years) were homogenized with respect to high wind speed and related to levels of forest damage. High maximum wind speed at the end of the 19th century and at the beginning of the 20th century was followed by low maximum wind speed in the 1940s, 1960s and 1970s. Since then, maximum values have increased. Gusts (extremes of the maximum wind speed) increased from the beginning of the recordings in 1933 and peaked in the early 1990s. Forest damage due to winter storms is best correlated with peak wind speed. Gusts exceeding 40 m/s and resulting in catastrophic windthrow have increased in recent winters. Copyright © 2009 Royal Meteorological Society [source]