The traditional threat score based on fixed thresholds for precipitation verification is sensitive to intensity forecast bias. In this study, the neighborhood precipitation threat score is modified by defining the thr...The traditional threat score based on fixed thresholds for precipitation verification is sensitive to intensity forecast bias. In this study, the neighborhood precipitation threat score is modified by defining the thresholds in terms of the percentiles of overall precipitation instead of fixed threshold values. The impact of intensity forecast bias on the calculated threat score is reduced. The method is tested with the forecasts of a tropical storm that re-intensified after making landfall and caused heavy flooding. The forecasts are produced with and without radar data assimilation. The forecast with assimilation of both radial velocity and reflectivity produce precipitation patterns that better match observations but have large positive intensity bias. When using fixed thresholds, the neighborhood threat scores fail to yield high scores for forecasts that have good pattern match with observations, due to large intensity bias. In contrast, the percentile-based neighborhood method yields the highest score for the forecast with the best pattern match and the smallest position error. The percentile-based method also yields scores that are more consistent with object-based verifications, which are less sensitive to intensity bias, demonstrating the potential value of percentile-based verification.展开更多
Using data from Population Censuses,1%National Population Sample Surveys of China and the Human Mortality Database,this article adopts robust percentile-based methods to analyze the changing trend of life expectancy o...Using data from Population Censuses,1%National Population Sample Surveys of China and the Human Mortality Database,this article adopts robust percentile-based methods to analyze the changing trend of life expectancy of the Chinese elderly especially the young-old and rural-urban disparity from 1989 to 2015,and attempt to explain the disadvantage of old-age mortality improvement in China compared to developed countries.We find that life expectancy at age 65 in China has increased continuously in recent decades,but at a lower speed than in developed countries,leading to a widening gap between China and developed countries,and the increase in e65 has not shown a clear catch-up trend that has been observed in the life expec-tancy at birth.Similar patterns are found when we explore the rural-urban disparity of China.Based on the age-at-death distribution,we find that the old-age deaths in rural areas are more concentrated at relatively younger ages compared to urban areas due to the higher death risks and slower improvement in mortality of the young-old in rural China.Our findings describe the age-patterns underlying the rural-urban disparity in life expectancy of the elderly within China,and also the main reason for the slower improvement of life expectancy among the Chinese elderly compared with those in developed countries.Survival improvement of the young-old and equalization of available health services are key to reducing the rural-urban bias and achieving accelerated increase in life expectancy among the elderly in China.展开更多
基金primarily supported by the National 973 Fundamental Research Program of China(Grant No.2013CB430103)the Department of Transportation Federal Aviation Administration(Grant No.NA17RJ1227)through the National Oceanic and Atmospheric Administration+1 种基金supported by the National Science Foundation of China(Grant No.41405100)the Fundamental Research Funds for the Central Universities(Grant No.20620140343)
文摘The traditional threat score based on fixed thresholds for precipitation verification is sensitive to intensity forecast bias. In this study, the neighborhood precipitation threat score is modified by defining the thresholds in terms of the percentiles of overall precipitation instead of fixed threshold values. The impact of intensity forecast bias on the calculated threat score is reduced. The method is tested with the forecasts of a tropical storm that re-intensified after making landfall and caused heavy flooding. The forecasts are produced with and without radar data assimilation. The forecast with assimilation of both radial velocity and reflectivity produce precipitation patterns that better match observations but have large positive intensity bias. When using fixed thresholds, the neighborhood threat scores fail to yield high scores for forecasts that have good pattern match with observations, due to large intensity bias. In contrast, the percentile-based neighborhood method yields the highest score for the forecast with the best pattern match and the smallest position error. The percentile-based method also yields scores that are more consistent with object-based verifications, which are less sensitive to intensity bias, demonstrating the potential value of percentile-based verification.
文摘Using data from Population Censuses,1%National Population Sample Surveys of China and the Human Mortality Database,this article adopts robust percentile-based methods to analyze the changing trend of life expectancy of the Chinese elderly especially the young-old and rural-urban disparity from 1989 to 2015,and attempt to explain the disadvantage of old-age mortality improvement in China compared to developed countries.We find that life expectancy at age 65 in China has increased continuously in recent decades,but at a lower speed than in developed countries,leading to a widening gap between China and developed countries,and the increase in e65 has not shown a clear catch-up trend that has been observed in the life expec-tancy at birth.Similar patterns are found when we explore the rural-urban disparity of China.Based on the age-at-death distribution,we find that the old-age deaths in rural areas are more concentrated at relatively younger ages compared to urban areas due to the higher death risks and slower improvement in mortality of the young-old in rural China.Our findings describe the age-patterns underlying the rural-urban disparity in life expectancy of the elderly within China,and also the main reason for the slower improvement of life expectancy among the Chinese elderly compared with those in developed countries.Survival improvement of the young-old and equalization of available health services are key to reducing the rural-urban bias and achieving accelerated increase in life expectancy among the elderly in China.
