Data modeling and assimilation studies with the MU radar
Data modeling and assimilation studies with the MU radar
复制标题
使用 MU 雷达进行数据建模和同化研究
DOI：
10.1016/s1364-6826(99)00021-8
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
W. Oliver
中科院分区：
文献类型：
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作者：
Shunrong Zhang;S. Fukao;W. Oliver
我们报告的数据建模和同化研究的初步结果，几个MU雷达实验。对一维电离层模型的各种输入进行调整，以提供与观测的一致性，并了解模型对其变化的敏感性。某些观测也直接用于模型中以锚定或约束其行为。特别是，借助O+、NO+、O+2和N+2密度的理论模型以及MU雷达对功率、离子漂移和等离子体温度分布的观测，对电离层100至500公里高度的电子密度进行了研究。本文选取了四个典型事例，定量地研究了等离子体漂移的（A）向北分量的影响（1986年12月15日），（B）大气成分（1986年10月7日），（C）太阳极紫外线通量（D）NmF 2、hmF 2和Neprofile模型上的上边界O+密度（1989年8月2日），以及根据hmF 2和漂移数据计算的中性风。它被发现，测量的垂直离子漂移定量地解释了测量的hmF 2（特别是在低太阳活动），而模型给出了一个更好的匹配与测量Newhen它使用hmF 2为基础的风，而不是测量的等离子体漂移。不同的大气O/N2比值和EUV通量以及不同的O+浓度上限值不仅可以显著改变NmF 2，而且可以显著改变hmF 2：较低的O/N2比值导致较高的hmF 2; EUVAC模型在高太阳活动时给出的hmF 2高于EUV 91模型;当O+浓度上限值较小时，hmF 2在白天较低，但在夜间变化不大。我们特别注意到，模型再现观测到的hmF 2所需的纬向风根据模型再现观测到的NmF 2的程度而不同。MSIS 86和EUV模型预测的不确定性也进行了讨论。结果表明，如果将MSIS和EUV 91模型结合起来使用，模型给出的NmF 2值比在太阳活动高时测得的值要高。因此，如果使用EUV 91，则需要从MSIS值降低O/N2比。如果使用EUVAC，则不需要大的修改。在低太阳活动的春分点，用任一EUV模型模拟产生的NmF 2值低于测量值，因此真实的O/N2比可能高于MSIS模型给出的值。
We report initial results of data modeling and assimilation studies for several MU radar experiments. Various inputs to a one-dimensional ionospheric model are adjusted to provide agreement with observation and also to learn the sensitivity of the model to their variations. Certain observations are also used directly in the model to anchor or constrain its behavior. In particular, studies of the electron density from 100 to 500 km altitude in the ionosphere are carried out with the help of a theoretical model of O+, NO+, O+2and N+2densities and MU radar observations of the power, ion-drift and plasma-temperature profiles. Four typical cases are selected to study quantitatively the effects of the (A) perpendicular-north component of the plasma drift (15 December 1986), (B) atmospheric composition (7 October 1986), (C) solar EUV flux (2 August 1989) and (D) upper-boundary O+density (5 October 1989) on the model NmF2, hmF2 and Neprofile, as well as on the neutral wind calculation from hmF2 and drift data. It is found that the measured vertical ion drift explains quantitatively well the measured hmF2 (particularly at low solar activity) while the model gives a better match with the measured Newhen it uses the hmF2-based wind rather than the measured plasma drift. Different model values of the atmospheric O/N2ratio and EUV flux and different values of the upper-bound O+density may modify not only NmF2 markedly but also hmF2: a lower O/N2ratio results in higher hmF2; the EUVAC model gives higher hmF2 at high solar activity than does the EUV91 model; with a smaller upper-bound O+density, hmF2 is lower by day but little changed by night. We specifically note that the meridional wind needed by the model to reproduce the observed hmF2 differed according to how well the model reproduced the observed NmF2. The uncertainties in the MSIS86 and EUV model predictions are also discussed. It is found that if the MSIS and EUV91 models are used together, the model gives an NmF2 higher than that measured at high solar activity. Thus the O/N2ratio needs to be reduced from the MSIS value if EUV91 is used. If EUVAC is used, no large modification is required. At equinox for low solar activity, modeling with either EUV model produces NmF2 values lower than those measured, and so the true O/N2ratio may be higher than that given by MSIS model.