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Major Storms (major + storm)
Selected AbstractsImpact of soil moisture on the development of a Sahelian mesoscale convective system: a case-study from the AMMA Special Observing PeriodTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue S1 2010Christopher M. Taylor Abstract Interactions between the land and atmosphere play an important role in the precipitation of the Sahel. The African Monsoon Multidisciplinary Analysis Special Observing Period provided observations with which to illuminate potential feedback mechanisms. This case-study highlights a major storm which developed over northern Mali in an area where a research aircraft was surveying the atmospheric response to soil moisture features. Soil moisture variability is characterized using satellite land-surface temperature data whilst cloud images illustrate the evolution of the storm and its relationship to the surface. Measurements in the planetary boundary layer (PBL) indicate mesoscale variations in pre-storm humidity and temperature consistent with high evaporation from wet soils. The storm developed above a dry surface within a wetter region with cells first appearing along a wet,dry soil boundary. This suggests that the storm was triggered in association with low-level convergence driven by the soil moisture pattern. A gravity wave propagating away from a remote mature storm also appears to have played an important role in the initiation, though only in the region of the soil moisture contrast did deep convection become established. Once organised into a Mesoscale Convective System, convection developed over wet areas as well as dry, and indeed at this stage, convection became more intense over wetter soils. This behaviour is consistent with the large gradients in PBL humidity. The study illustrates the complexity of soil moisture,convection feedback loops and highlights the mechanisms which may operate at different stages of a storm's life cycle. Copyright © 2009 Royal Meteorological Society [source] SOIL EROSION AND SEDIMENT YIELD PREDICTION ACCURACY USING WEPP,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2004John M. Laflen ABSTRACT: The objectives of this paper are to discuss expectations for the Water Erosion Prediction Project (WEPP) accuracy, to review published studies related to WEPP goodness of fit, and to evaluate these in the context of expectations for WEPP's goodness of fit. WEPP model erosion predictions have been compared in numerous studies to observed values for soil loss and sediment delivery from cropland plots, forest roads, irrigated lands and small watersheds. A number of different techniques for evaluating WEPP have been used, including one recently developed where the ability of WEPP to accurately predict soil erosion can be compared to the accuracy of replicated plots to predict soil erosion. In one study involving 1,594 years of data from runoff plots, WEPP performed similarly to the Universal Soil Loss Erosion (USLE) technology, indicating that WEPP has met the criteria of results being "at least as good with respect to observed data and known relationships as those from the USLE," particularly when the USLE technology was developed using relationships derived from that data set, and using soil erodibility values measured on those plots using data sets from the same period of record. In many cases, WEPP performed as well as could be expected, based on comparisons with the variability in replicate data sets. One major finding has been that soil erodibility values calculated using the technology in WEPP for rainfall conditions may not be suitable for furrow irrigated conditions. WEPP was found to represent the major storms that account for high percentages of soil loss quite well,a single storm application that the USLE technology is unsuitable for,and WEPP has performed well for disturbed forests and forest roads. WEPP has been able to reflect the extremes of soil loss, being quite responsive to the wide differences in cropping, tillage, and other forms of management, one of the requirements for WEPP validation. WEPP was also found to perform well on a wide range of small watersheds, an area where USLE technology cannot be used. [source] Areal PMP distribution of one-day to three-day duration over IndiaMETEOROLOGICAL APPLICATIONS, Issue 4 2002C P R Clark Rakhecha There is a need to assess the areal depth of the probable maximum precipitation (PMP) over specified catchment areas for the safe construction of dam spillways. The large number of dams in India, coupled with their risk of failure, makes this need imperative both for the maximum use of water resources and for public safety. On the basis of rainfall data for the heaviest storms that occurred in different parts of India during the period 1880,1983, improved estimates of one-, two-, and three-day point PMP for India have been made. In this paper the distribution of areal PMP over specified catchment sizes is provided for the first time. The areal reduction factors (ARF) were based on envelope curves of major storms to give the ARF for areas of 10,20,000 km2 . These factors were found to vary from 1.0 to 0.41, though there was no real difference between durations of rainfall. These values of ARF were then multiplied by values of one- to three-day PMP. The resulting maps allow a broad description of the spatial distribution of areal PMP and also provide a rapid and consistent estimate of the probable maximum flood (PMF) from the PMP. For 500 km2 the areal PMP varies from 40 to 120 cm for one-day duration; from 70 to 200 cm for twoday duration; and from 75 to 270 cm for three-day duration. The pattern of PMP is consistent with the geography and available moisture. Copyright © 2002 Royal Meteorological Society. [source] School Kids and Oil Rigs: Two More Pieces of the Post-Katrina Puzzle in New OrleansAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 2 2010Kelly Frailing Shortly after Hurricane Katrina's landfall in August 2005 and the reports of rampant looting of businesses in the city, we became curious about the extent of Katrina looting as compared to that after other major storms that hit New Orleans in 1947 and in 1965. Using burglary as a proxy variable for looting, we discovered that the burglary rates in the month before and the month after Katrina were significantly higher than those before and after the other two hurricanes. We then investigated the socioeconomic conditions in the city in an effort to explain these numbers. Population loss and high unemployment rates, coupled with a decline in high-paying manufacturing jobs and an increase in low-wage food and hotel service jobs generated severe economic inequality in the city that exacerbated the situation created by Katrina. Our current analysis of the impact of public school desegregation and the oil bust suggests that both events contributed to population loss and the increase in low-wage jobs prior to the storm. We believe that this type of research can assist in the recovery of New Orleans by providing an understanding of the city's pre-Katrina social and economic conditions and make clearer which post-Katrina changes are desirable. [source] | ||||||||||