Duration of an ionospheric data assimilation initialization of a coupled thermosphere‐ionosphere model
Duration of an ionospheric data assimilation initialization of a coupled thermosphere‐ionosphere model
复制标题
热层-电离层耦合模型的电离层数据同化初始化的持续时间
DOI：
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
L. Zhu
中科院分区：
文献类型：
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作者：
G. Jee;A. Burns;W. Wang;S. Solomon;R. Schunk;L. Scherliess;D. Thompson;J. Sojka;L. Zhu
初始条件是气象学和海洋学中精确数值预报模式的关键输入。在本文中，我们解决这个问题的热层电离层系统的空间天气预报模式，通过使用电离层测量的全球同化（GAIM）模型的电子密度初始化的热层电离层嵌套网格（TING）模型的电离层部分。在2004年4月初的地磁平静和扰动时期，将GAIM初始化的TING模型（G-TING）的电子密度与独立TING模型（S-TING）的输出进行比较，以观察初始化的影响会持续多久。我们的研究表明，在大多数情况下，初始化的电子折叠时间约为2 - 3小时，尽管如果包括热层的初始化，这个结果可能会有所不同。然而，这个弛豫时间显示出随纬度、当地时间和高度的显着变化，它也可能取决于G-TING和S-TING之间的初始电子密度差异。此外，正（G-TING> S-TING）和负（G-TING <S-TING）密度差具有不同的初始化效应持续时间。我们的研究还表明，尽管磁暴对热层-电离层系统有影响，但弛豫时间随地磁活动的变化很小。
Initial conditions provide a critical input for accurate numerical forecast models in meteorology and oceanography. In this paper, we address this problem in space weather forecast models of the thermosphere‐ionosphere system by using the electron densities from the Global Assimilation of Ionospheric Measurements (GAIM) model to initialize the ionospheric part of the Thermosphere Ionosphere Nested Grid (TING) model. The electron densities from the GAIM‐initialized TING model (G‐TING) are compared with the output from the stand‐alone TING model (S‐TING) for geomagnetically quiet and disturbed times in the early April 2004 period in order to observe how long the effects of the initialization would last. Our study shows that the e‐folding time of the initialization is about 2 ∼ 3 hours for most conditions, although this result would probably be different if the initialization for the thermosphere is also included. However, this relaxation time displays significant variations with latitude, local time, and height, and it may also depend on the initial electron density differences between G‐TING and S‐TING. Furthermore, positive (G‐TING > S‐TING) and negative (G‐TING < S‐TING) density differences have different time durations of the initialization effects. Our study also indicates that there is little variation of the relaxation time with the geomagnetic activity despite the impact of geomagnetic storms on the thermosphere‐ionosphere system.