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The characteristics of the atmospheric boundary layer height over the global ocean were studied based on the Constellation Observation System of Meteorology, Ionosphere and Climate (COSMIC) refractivity data from 2007 to 2012. Results show that the height is much characteristic of seasonal, inter-annual and regional variation. Globally, the spatial distribution of the annual mean top height shows a symmetrical zonal structure, which is more zonal in the Southern Hemisphere than in the Northern Hemisphere. The boundary layer top is highest in the tropics and gradually decreases towards higher latitudes. The height is in a range of 3 to 3.5 km in the tropics, 2 to 2.5 km in the subtropical regions, and 1 to 1.5 km or even lower in middle and high latitudes. The diurnal variation of the top height is not obvious, with the height varying from tens to hundreds of meters. Furthermore, it is different from region to region, some regions have the maximum height during 9:00 to 12:00, others at 15:00 to 18:00. 相似文献
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COSMIC计划于2006年成功实施,该计划的设计寿命为5 a。由于实际运行期间COSMIC星座内卫星出现过技术故障,加上卫星姿态控制不稳定等原因,探测数据资料的质量存在一定的波动。为了对COSMIC掩星后期的数据质量进行评估,以全球无线电探空数据为参照,对COSMIC掩星折射率廓线数据进行了统计分析。分析结果表明:1)在两类观测资料观测时间和空间的配对标准上,随着时间差限值与距离差限值的增大,折射率的平均相对误差的变化趋势性不强,但相对误差标准偏差呈增加趋势。2)折射率偏差大值区集中在东南亚附近海域和墨西哥湾附近海域,在海陆交界处折射率平均相对误差要大于陆地和海洋上的平均相对误差。3)10 km以下,热带地区的正偏差最大,平均相对误差为0.849%,高于北半球的0.484%和南半球的0.492%。在10 km以上,三个区域平均相对误差的差异不明显。4)10 km以下,夏季折射率的平均相对误差最大,为0.663%;冬季折射率的平均相对误差最小,为0.365%;30—35 km冬季的平均相对误差最大,达到1.014%。 相似文献
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Ken-ichi SHIMOSE Ming XUE Robert D. PALMER Jidong GAO Boon Leng CHEONG David J. BODINE 《大气科学进展》2013,30(2):291-305
Because they are most sensitive to atmospheric moisture content, radar refractivity observations can provide high-resolution information about the highly variable low-level moisture field. In this study, simulated radar refractivity-related phase-change data were created using a radar simulator from realistic highresolution model simulation data for a dryline case. These data were analyzed using the 2DVAR system developed specifically for the phase-change data. Two sets of experiments with the simulated observations were performed, one assuming a uniform target spacing of 250 m and one assuming nonuniform spacing between 250 m to 4 km. Several sources of observation error were considered, and their impacts were examined. They included errors due to ground target position uncertainty, typical random errors associated with radar measurements, and gross error due to phase wrapping. Without any additional information, the 2DVAR system was incapable of dealing with phase-wrapped data directly. When there was no phase wrapping in the data, the 2DVAR produced excellent analyses, even in the presence of both position uncertainty and random radar measurement errors. When a separate pre-processing step was applied to unwrap the phase-wrapped data, quality moisture analyses were again obtained, although the analyses were smoother due to the reduced effective resolution of the observations by interpolation and smoothing involved in the unwrapping procedure. The unwrapping procedure was effective even when significant differences existed between the analyzed state and the state at a reference time. The results affirm the promise of using radar refractivity phase-change measurements for near-surface moisture analysis. 相似文献
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大气折射指数垂直分布的气候特征计算 总被引：1，自引：0，他引：1
建立了南京地区大气折射指数垂直分布关系式，并计算了不同气候时段下分布参数、拟合误差以及Ｎ单位垂直变化梯度。结果表明：不同气候时段的累年年平均垂直分布参数不同，但差异并不明显；逐年年平均垂直分布参数间的差异较明显；累年逐月平均垂直分布不同月份间的参数差异很大，具有明显的季节性；逐年逐月平均垂直分布较全面地反映出分布的气候时段性、年际特性、季节特性及月际特性。还建立了一种考虑随机时间序列振动位相的多元 相似文献
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利用欧盟的METOP-1、美国的GRACE A、我国台湾的COSMIC掩星折射率资料,以美国NCEP开发的GSI同化系统为平台,对2012年6月10-13日华南地区一次准静止锋引起的暴雨过程进行了循环同化模拟和分析,以探讨GPS掩星同化对我国华南暴雨预报的影响。为考察GPS掩星折射率资料的同化效果,以及循环同化对GPS折射率资料同化效果的影响,设计了3组模拟对比试验:第一组不同化GPS掩星折射率资料;第二组只同化一个时次的GPS掩星折射率资料;第三组循环同化26 h的GPS掩星折射率资料。试验结果表明:1)循环同化的暴雨预报效果比单时次同化的暴雨预报效果好,表明掩星折射率资料的使用需要有较长时间的累积才能产生较好效果;2)掩星资料对分析和预报的温度场和湿度场调整的贡献较大,对风场的调整也有一定贡献;3)循环同化GPS掩星折射率资料的预报效果,在降水强度、降水中心位置和TS评分方面均优于未同化掩星折射率资料的预报效果。 相似文献
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山基GPS掩星技术可以精确获得低层大气折射率信息,其观测原理是:在高山的山顶安装GPS接收机,跟踪GPS卫星的低仰角和负仰角信号,通过载波相位的变化求出大气折射造成的弯曲角剖面,从而利用科学反演方法获得观测点高度以下的大气折射率剖面.为了对山基掩星测量数据进行验证,2005年8月1日～29日,在河北雾灵山(40.60°N,117.48°E,2118m)开展了为期一个月的山基GPS掩星观测与其他探测的时比实验.实验所用的JAVAD双频GPS接收机共工作576小时,接收机朝南观测,记录到山基掩星事件1136次,其中上升掩星621次,下降掩星515次.实验期间,在雾灵山顶利用自动气象观测仪每天24小时观测当地的温度、湿度和气压,由此可计算大气折射率.本文利用雾灵山GPS掩星实验所获得的观测数据,成功反演得到大气折射率剖面,并将所得接收机高度的折射率与雾灵山顶自动气象站观测结果进行比对,分析结果表明:山基GPS掩星和自动气象站观测结果是一致的.山基GPS掩星观测可为低层大气环境监测提供大量数据,具有潜在的应用前景. 相似文献
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本文简要阐述了山基GPS掩星数据处理过程,介绍了雾灵山(40.60.N,117.48.E,～2118 m)山基GPS掩星观测实验的基本情况,将雾灵山山基GPS掩星折射率与探空折射率进行了比较.按照山基掩星和无线电探空在空间(经纬度)上相差在2.以内、时间上相差在1.5 h以内的条件,共选出了206个山基掩星折射率廓线样本用于比较分析.山基掩星折射率与探空折射率的个例比较,表明山基掩星折射率廓线合理,且和探空折射率基本一致.统计结果显示,在2100 m 以下,山基掩星折射率与探空折射率相对偏差的平均值为-2.0%,标准偏差为7.3%. 相似文献
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