利用2007-2010年的中国探空资料评估GPS掩星探测系统COSMIC（constellation observing system for meteorology,ionosphere，and climate）反演产品，对比数据在空间上限定掩星事件发生地和探空站的水平距离在100km以内，在时间上相差...利用2007-2010年的中国探空资料评估GPS掩星探测系统COSMIC（constellation observing system for meteorology,ionosphere，and climate）反演产品，对比数据在空间上限定掩星事件发生地和探空站的水平距离在100km以内，在时间上相差不超过1小时，对比高度范围为925～10hPa。对比结果表明，COSMIC反演大气温度略低于探空仪测量值，平均绝对偏差为-0．08K，标准差为1．67K。两者水汽资料在200hPa以上高度有系统性偏差；在200hPa以下，比湿的平均偏差约为＋0．080g／kg，标准差为0．692g／kg，水汽压平均相对误差约为＋69．6％，标准差为160．O％，水汽压存在极端低值的异常情况。通过对全球不同区域6种探空仪的对比，COSMIC反演产品在700hPa以下高度显著受背景场影响，由于背景场误差随区域改变，因此，只有在精度要求不高的情况下，COSMIC反演产品才适合用于评估其他资料。展开更多
Haze and fog exhibit different microphysical and optical properties according to Mie scattering theory. Haze particles are smaller than fog droplets. Light of a shorter wavelength is reduced more than that of a longer...Haze and fog exhibit different microphysical and optical properties according to Mie scattering theory. Haze particles are smaller than fog droplets. Light of a shorter wavelength is reduced more than that of a longer wavelength during haze events. In fog, the differences between the extinction coefficients at different wavelengths are not as apparent. On the basis of the different light extinction characteristics of haze and fog, a novel four-wavelength transmissometer based on charge-coupled device （CCD） imaging was designed to distinguish haze from fog with central wavelengths at 415, 516, 650, and 850 nm. The four-wavelength transmissometer was tested in an insitu experiment during the winter of 2009. Fog was determined when the differences of the extinction coefficients at the four wavelengths were not notable, whereas haze was determined when the light at shorter wavelengths was significantly more reduced than that at longer wavelengths. A threshold which describes the relative size of the extinction coefficients at the four wavelengths was defined to distinguish between fog and haze. The four-wavelength transmissometer provided results consistent with the commercial fog monitor during several measurements made in fog and haze events, especially under conditions of low visibility and high relative humidity.展开更多
文摘利用2007-2010年的中国探空资料评估GPS掩星探测系统COSMIC（constellation observing system for meteorology,ionosphere，and climate）反演产品，对比数据在空间上限定掩星事件发生地和探空站的水平距离在100km以内，在时间上相差不超过1小时，对比高度范围为925～10hPa。对比结果表明，COSMIC反演大气温度略低于探空仪测量值，平均绝对偏差为-0．08K，标准差为1．67K。两者水汽资料在200hPa以上高度有系统性偏差；在200hPa以下，比湿的平均偏差约为＋0．080g／kg，标准差为0．692g／kg，水汽压平均相对误差约为＋69．6％，标准差为160．O％，水汽压存在极端低值的异常情况。通过对全球不同区域6种探空仪的对比，COSMIC反演产品在700hPa以下高度显著受背景场影响，由于背景场误差随区域改变，因此，只有在精度要求不高的情况下，COSMIC反演产品才适合用于评估其他资料。
基金Supported by the National (Key) Basic Research and Development (973) Program of China (2011CB403402)Basic Research Fund of the Chinese Academy of Meteorological Sciences (2008Z011)China Meteorological Administration Special Public Welfare Research Fund (GYHY200906025)
文摘Haze and fog exhibit different microphysical and optical properties according to Mie scattering theory. Haze particles are smaller than fog droplets. Light of a shorter wavelength is reduced more than that of a longer wavelength during haze events. In fog, the differences between the extinction coefficients at different wavelengths are not as apparent. On the basis of the different light extinction characteristics of haze and fog, a novel four-wavelength transmissometer based on charge-coupled device （CCD） imaging was designed to distinguish haze from fog with central wavelengths at 415, 516, 650, and 850 nm. The four-wavelength transmissometer was tested in an insitu experiment during the winter of 2009. Fog was determined when the differences of the extinction coefficients at the four wavelengths were not notable, whereas haze was determined when the light at shorter wavelengths was significantly more reduced than that at longer wavelengths. A threshold which describes the relative size of the extinction coefficients at the four wavelengths was defined to distinguish between fog and haze. The four-wavelength transmissometer provided results consistent with the commercial fog monitor during several measurements made in fog and haze events, especially under conditions of low visibility and high relative humidity.
