两种数据在海洋大气折射环境中的应用评估

海上大气折射率是影响电波传播的重要因子,是构建电波环境数据库的重要元素.而再分析数据是其重要的数据源,因此本文利用典型海域的GPS探空数据从两个方面开展了欧洲中期天气预报中心ERA-I(ERA-interim)和美国国家环境预报中心FNL(FiNal)再分析数据在大气折射环境的应用评估,包括直接应用和作为初始场开展数值模拟.结果表明:在靠近大洋的“开阔”海域,FNL再分析数据对大气折射率环境的适应性更好,其中在北极、南极海域,FNL数据计算的修正大气折射率的均方根误差(rootmeansquareerror,RMSE)分别为4.7和2.8 M单位;而在相对封闭的海域,ERA-I再分析数据刻画的大气折射更准确.大气波导识别方面,ERA-I再分析数据能识别大部分波导,而FNL再分析数据只能识别小部分波导尤其是海上波导,在波导高发的中东地区,二者正确率分别为58.1%和45.4%.在数值模拟中,两种不同数据初始场对模拟大气折射率的影响不大,各站点计算修正大气折射率的RMSE均小于1M单位.研究结果可对不同海域大气折射环境应用提供指导.

ERA-I数据在南海大气折射率环境中的应用评估

海上大气折射率环境是影响电磁波传播、目标探测准确性的关键因素之一.文中利用南海的GPS探空数据评估了ERA-I(ERA-Interim)再分析数据计算的大气折射率,结果表明:3000 m以下修正大气折射率整体标准差为9.2 M单位,相对误差为1.4%;在分布上修正大气折射率误差在低层偏小,并且会发生小幅震荡,边界层顶以上偏大,这与大气层内水汽分布密切相关,相关系数为0.94.此外两种数据识别的波导参数中,波导高度拟合斜率接近1,最准确;波导厚度和强度斜率不到0.5,波导厚度偏厚,而强度偏小.说明ERA-I再分析数据是较为可靠的数据源,可用来研究海上大气折射环境特性.

南海海域海表面温度对低空大气波导数值模拟的影响研究

为了研究海表面温度(sea surface temperature,SST)对低空大气波导数值模拟的影响,针对南海海域基于天气研究与预报(weather research and forecasting,WRF)模式开展了不同SST对低空大气波导数值模拟的影响研究.结果表明:精确的SST对低空大气波导数值模拟影响最大,其次是更新周期;美国国家海洋和大气管理局(National Oceanic and Atmospheric Administration,NOAA)提供的最优插值SST给出的大气波导模拟结果最好,正确率为68.2%,且波导底高平均误差和标准差最小,这是由于其模拟的相对湿度和气温变化较为准确,其次为气候预报再分析系统(climate forecast system reanalysis,CFSR)给出的SST方案较好;此外不同嵌套网格方式对大气波导数值模拟也有影响,在最优方案中子网格模拟的大气波导正确率和发生概率分别提高了11.8%和10.4%,虚报率降低了2.4%.该研究可为南海低空大气波导的精确预报提供技术支撑.

Statistical characteristics of the surface ducts over the South China Sea from GPS radiosonde data

Based on the global position system （GPS） radiosonde data near the sea surface, the surface duct characteristics over the South China Sea （SCS） were statistically analyzed. The annual surface duct occurrence over the SCS was about 64%. Of the observed surface ducts, duct heights mainly distributed between 18 and 42 m, with M slopes in the range of -0.3 to -0.2 M units/m. Those ducts accounted for about 80% of the ducting cases. For the total profiles, the duct occurrences in a day changed slowly and were more than 60% in all times. The surface ducts formed more easily in the daytime than in the nighttime and most of the duct height were at bellow about 32 m. Additionally, The seasonal variation of the SCS ducts appeared to be evident, except that the mean duct thickness was almost constant, about 33 m for all seasons. The highest occurrence was about 71% in the autumn, followed by in the summer, spring and winter. In spring, their top-height existed more often at a height of more than 48 m. Their mean duct strength became stronger trend from spring to winter, with the M-slope in the range between -0.26 and -0.18 M units/m. Those results agreed well with other studies, provided considering the data resolution. The statistical analysis was reliable and gave the duct estimation for the SCS. Such duct climatology not only has important implications for communication systems and the reliability of the radar observation, but also can provide useful information to improve the accuracy of the meteorological radar measurements.

An Idea of Extracting Fresh Water from the Atmosphere

Based on principles of vapor coagulation, a method of extracting fresh water from the atmosphere was put forward. Its principles are simple, and it is easy to make and install the equipment made cheaply. Moreover, there is no or much less energy consumed during the extraction process, so there is no environmental pollution. In a word, this method of extracting fresh water from the atmosphere is of great practical value.

基于优质线上教学资源的海洋潮汐学课程教学改革实践

优质线上课程为高等院校师生提供了宝贵的教育资源。高等院校理工类课程广泛存在课程内容多、理论性强和各个章节内容环环相扣等特点,学生学习难度大。该文以海洋潮汐学课程为例,提出将优质线上教学资源引入教学过程,充分发挥线上课程"名师名教"和线下课程"实时互动"的优势,旨在提高授课质量,解决学时不足情况下一部分学生因准备不充分而感到吃力以及另一部分学生希望增加教学内容的问题。此外,在教学过程中引入智慧教学工具雨课堂,能够解决学生学习效果反馈效率低的问题。