A technique for estimating a plasma drift velocity distribution in the ionosphere is presented. This technique is based on a framework for representing a global vector field on a sphere by using a set of localized basis functions which is newly derived as a variant of the spherical elementary current system (SECS). A vector field on a sphere can be divided into its divergence-free (DF) component and curl-free (CF) component. The DF and CF components can then be represented by weighted sums of the DF and CF vector-valued basis functions, respectively. While the SECS basis functions have a singular point, the new basis functions do not diverge over a sphere. This property of the new basis function allows us to achieve robust prediction of the drift velocity at any point in the ionosphere. Assuming that the ionospheric plasma drift velocity has no divergence, its distribution can be represented by a weighted sum of the DF basis functions. The proposed technique estimates the ionospheric plasma drift velocity distribution from the SuperDARN data by using the DF basis functions. Since there are some wide gaps in the spatial coverage of the SuperDARN, an empirical convection model is combined with the framework based on the new basis functions. It is demonstrated that the proposed technique is useful for the estimation and modeling of the ionospheric plasma velocity distribution.

中文翻译：

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使用局部基函数估计球面矢量场的框架及其在 SuperDARN 数据处理中的应用

介绍了一种用于估计电离层中等离子体漂移速度分布的技术。该技术基于一个框架，用于通过使用一组局部基函数来表示球体上的全局矢量场，该函数是作为球形基本电流系统 (SECS) 的一个变体新推导出来的。球体上的矢量场可分为无散度 (DF) 分量和无卷曲 (CF) 分量。然后，DF 和 CF 分量可以分别由 DF 和 CF 向量值基函数的加权和表示。虽然 SECS 基函数有一个奇异点，但新的基函数不会在球体上发散。新基函数的这一特性使我们能够对电离层中任何点的漂移速度进行可靠的预测。假设电离层等离子体漂移速度没有发散，它的分布可以用DF基函数的加权和来表示。所提出的技术通过使用 DF 基函数估计来自 SuperDARN 数据的电离层等离子体漂移速度分布。由于 SuperDARN 的空间覆盖范围存在较大差距，因此将经验对流模型与基于新基函数的框架相结合。结果表明，所提出的技术可用于电离层等离子体速度分布的估计和建模。由于 SuperDARN 的空间覆盖范围存在较大差距，因此将经验对流模型与基于新基函数的框架相结合。结果表明，所提出的技术可用于电离层等离子体速度分布的估计和建模。由于 SuperDARN 的空间覆盖范围存在较大差距，因此将经验对流模型与基于新基函数的框架相结合。结果表明，所提出的技术可用于电离层等离子体速度分布的估计和建模。