海上低空大气波导的遥感反演及数值模拟研究

IOCAS-IR > 海洋环流与波动重点实验室

	海上低空大气波导的遥感反演及数值模拟研究
其他题名	A Study on Atmospheric Ducts over the Sea Retrieval with AMSR-E Satellite Data and its Numerical Simulation
	成印河
学位类型	博士
	2009-05-27
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	大气波导蒸发波导 Amsr-e数据 Mm5模式数值模拟
摘要	由于电磁波传播技术的广泛应用，大气环境成为电磁波传播研究的一个重要领域，尤其是天气变化多端的对流层。对流层大气波导是对流层大气的一种异常结构。大气波导可以使通信电路的相互干扰问题变得复杂，既可能干扰其他系统,又可能形成另外的系统，可以使探测系统产生超视距探测、雷达盲区等反常传播问题。然而通信系统或雷达探测系统遭受大气波导影响的时机具有很大的偶然性，它完全取决于对流层大气的特点。假如能够掌握大气波导的变化规律，准确而及时地预测、预报其出现的时间和地域，结合频率、射线波束、天线仰角和发生功率的选择，就能更好地发挥探测及通信设备的作用。因此，根据实际大气环境，分析、预测和预报大气波导，对于评估大气环境对电磁波传播和探测系统性能具有重要的理论意义和实际价值，尤其是在军事领域。然而在海洋大气环境中，特别是在广阔的海洋上，传统的海洋测量手段，如浮标、船只，获取的海洋水文数据稀少，探空数据更少，无法满足现代海洋大气环境监测所需的大范围观测信息，即使获取数据也很难保证数据点时间和空间的有效性；同时海洋大气边界层日变化缓慢，发生的大气波导持续时间长，比较稳定，对于海上舰船通讯等急需开展大气波导环境区域研究。我国是海洋大国，海岸线狭长，更需要开展沿海区域及近海对流层大气波导研究，特别是边界层内低空大气波导环境预测、预报研究。目前国内大气波导的研究大多数情况下只注重单站波导发生情况，其代表的时空有效性是有限的，而在实际应用中，人们更加关注波导存在区域，因为波导区域决定了电磁波传输范围。本文针对我国近海区域大气波导不同的形成机理和类型，分别进行了研究。对于蒸发波导，本文利用卫星遥感获取海水表面温度、海面风场、气温、相对湿度等资料，建立卫星遥感资料与蒸发波导高度之间的诊断模式，研究大气波导反演算法和预测模型，首次分析了蒸发波导高度的空间不均匀性。对于低空表面波导和悬空波导，利用中尺度数值模式MM5对大气波导进行了系统的研究，填补了国内中尺度大气波导数值模拟研究的空白，同时选取典型的天气过程，进行了中尺度数值模拟个例研究，分析了大气波导形成机理。本文主要工作如下：一、结合P-J模式，利用AMSR-E卫星数据用两种神经网络方法反演了热带海域的蒸发波导高度，并进行了比较，两种方法得到的与浮标实测参数计算得到的蒸发波导高度之间的相关系数相当，都为0.82左右，均方根差后者比前者小，分别为2.64米和1.89米。神经网络直接反演蒸发波导高度方法要优于间接反演蒸发波导高度的方法。利用AMSR-E卫星数据直接反演了南海海域的蒸发波导高度，可以清楚看出蒸发波导高度的空间分布的不均匀性，为研究蒸发波导的环境特性奠定基础。二、以2005年6月2日出现在黄海海域的大气波导为例，设计了三种数值试验，利用MM5模式对大气波导进行了24h数值模拟研究，包括是否加入常规探空资料进行格点分析同化，垂直分层的多寡，粗、细网格模拟比较分析。通过研究得到了以下结论：（1）利用常规资料进行格点同化对海上大气波导影响较小，对陆地影响较大；（2）垂直分层对大气波导特征参数影响明显，层数较多描述大气波导比较合适；（3）对于海上大气波导，细网格刻画大气波导特征参数比较细致，但粗网格的模拟已经足够进行大气波导分析。三、以NCEP再分析资料为背景场,利用MM5模式，对2005年6月2日至4日出现在黄海海域的大气波导和2008年5月10日12时到11日12时由‘威玛逊’台风引起的大气波导分别进行了数值模拟研究。通过研究发现：模拟的修正折射率廓线与探空数据得到的廓线基本吻合，但是模拟的较强波导强度和高度普遍比实测的要小得多；同时给出了大气波导参数的演变过程，分析了两次大气波导形成的天气过程，说明了模拟的大气波导区域是可靠的和可信的； MM5模式能够模拟出特定天气条件下低空较强大气波导三维空间变化过程，可以为定量地描述大气波导特征提供理论和试验依据。
其他摘要	The atmospheric enviorenment has become an important field of propagation of radio waves with the technique of electromagnetic wave propagation wildly used recently, especially in the changeful troposphere. The atmospheric duct is a kind of abnormal structure in the troposphere air. Because of radio wave anomalous propagation along the atmospheric ducts, the problems of the co-channel interference are more complicate for communication systems with the results of intersystem interference and the formation of other system. Besides those, for surveillance equipments such as radar they can produce radar holes or the extensions of detect range. Howere, the occurrence of the atmospheric duct is stochastic and lies on the characters of the troposphere air process absolutely. If the changeful law of the atmospheric duct is drawn and its occurring time and extension are estimated and forecasted, the surveillance equipments can exert all their powers to work well, based on frequency, launching elevation and so on. So based on the real data from the atmosphere and sea, atmospheric ducts can be analysed, estimated and forecasted, which has great theoretical significance and is of great value espically to military when effects of atmospheric duct on propagation of radio waves and functions of surveillance equipments are estimated. The meteorological ocean data and sounding data, are very scarce by traditional measurements such as buoys and vessels in the marine- atmospheric environment, especially over the wide ocean, which can not meet present needs. What’s more, the diurnal marine atomaspheric boundary layer changes slowly on the ocean, the atmospheric ducts last long and are stable. Many countries are interested with them. China is one of the greatest countries of the ocean and owns long coastline so the researches of tropospheric duct in coastal waters, especialy in marine atmospheric boundary layer are being developed urgently. The researches are conducted according to the evolution mechanisms and duct types separately. The most interior current studies are concentrated on single sounding site duct conditions. However more attentions are paid on the extent of existing duct in practice. So the paper founds coupling models between satellite remote data and evaporation duct height, studies retrieval arithmetic and estimates models using the sea surface temperature, wind speed, air temperature, relative humidity near the sea retrieved from the satellite remote data. Besides those, evaporation duct asymmetric distributions are analyzed with the above method firstly. Then the Pennsylvannia State Universtity/National Center for Atmospheric Research Fifth Generation Mesoscale Model (MM5) is used to simulate the elevated ducts and surface ducts and analyze the evolution mechanisms. Simulation of atmospheric duct with the MM5 is studied system systemically which is filled up the gap in interior Simulation of atmospheric duct. The conclusions derived from these researches are following: （1）Two methods based on the multiparameter neural network and P-J model are proposed to retrieve the evaporation duct from the AMSR-E data. One is to retrieve the sea surface parameters and then calculate the evaporation duct, the other is to retrieve the evaporation duct directly. The correlation coefficients between estimated evaporation duct from AMSR-E data and calculated by P-J model from buoy measurements parameters are all about 0.82 and root-mean-square errors of them are 2.64 meters and 1.89 meters respectively. So the first method is better than the second one. The evaporation ducts of South China Sea are retrieved from AMSR-E data using the later method and evaporation duct asymmetric distributions are analyzed from the retrieved results. （2）The paper takes example for the atmospheric ducts occurred in Yellow sea from from Jun 2 to Jun 3 of 2005 and designs several numerical tests to simulate the the atmospheric ducts for 24 hours with MM5 model, including whether or not using data assimilation with routine sounding and ground data and how much levels the models used etc. Some conclusions are inducted through the study: first, grid nudging with the rountine observed data in the MM5 simulation of atmospheric duct affects less over the sea than the land;Second,how much of sigma levels have great influence on simulation of atmospheric duct and the MM5 simulation with more sigma levels depicting the atmospheric ducts are reasonable; Last, multiple nests are allowed on a given level of nesting domain in the MM5 model.The mother domain has the ability enough to simulate the atmospheric duct over the sea than the sub-domain. （3） Two numerical simulations of atmospheric duct process in the Yellow Sea is produced with MM5 atmospheric model based on NCEP reanalyzed data. One is from Jun 2 to Jun 4 of 2005 and the other one is from May 10 to May 11 resulted from No 2 typhoon‘RAMMASUN’in 2008. The simulated results corresponding to upper Observation stations are consistent with the profiles from the sounding balloons basically, but the simulated duct parameters such as duct strength are less than those from sounding balloons generally. The duct parameters evolution processes are given and synoptic processes are analyzed. The results show that the temporal and spacial evolutions of the simulated duct parameters are reasonable and authentic and MM5 model can simulate the evolution of atmospheric ducts and describe the characters of them.
页数	114
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/693
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	成印河. 海上低空大气波导的遥感反演及数值模拟研究[D]. 海洋研究所. 中国科学院海洋研究所,2009.

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