GEM: Model of the Low-Latitude Boundary Layer

GEM：低纬度边界层模型

• 批准号: 9401056
• 负责人: Bengt Sonnerup
• 金额: $ 13.2万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-01 至 1998-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9401056&HistoricalAwards=false
• 关键词: GEM; Model; Low; Latitude; Boundary

It is proposed to develop a numerical model of the low- latitude boundary layer (LLBL), located in the equatorial region of the Earth's magnetoshpere adjacent to its outer boundary, the magnetopause, and the coupling of that layer to the dayside auroral ionosphere via field-aligned currents. The model is intended as a building block in the construction of a global geospace circulation model (GGCM) with predictive capability. Two versions of the LLBL model will be developed. First, a relatively sophisticated self-consistent model of steady plasma flow, magnetic fields and currents will be completed and its parameters constrained by comparison with observations. In this model, partial differential equations are solved numerically in the boundary layer approximation. On the basis of results and experience gained from this model a simpler version, based on ordinary differential equations, will be developed for use in parallel with, and coupled to, existing models, or models under development as part of the GEM program, of internal magnetospheric convection on one side of the layer and external solar-wind plasma flow on its other side. This simpler version of the boundary-layer model will have as its basic theoretical elements: (i) the equation of momentum conservation in the flow direction integrated over the thickness of the boundary layer and (ii) polynomial (or other parametric) representations of variations across the boundary layer, with free parameters that will allow the model to accommodate, perhaps iteratively, boundary conditions provided by an internal circulation model and an external flow model. The simpler model which is expected to be numerically fast will be benchmarked by comparison w ith the self-consistent boundary layer code (which is computationally too slow to be used in a GGCM), as well as with observed ionospheric and equatorial signatures of the layer.

本文提出发展一个赤道低纬边界层的数值模式 地球磁层与其外边界相邻的区域，磁层顶，以及该层的耦合 到白昼极光电离层通过场对准 电流。 该模型旨在作为 全球地球空间环流模式的建立 （GGCM）具有预测能力。 两个版本的 将开发LLBL模型。 首先，相对 稳定等离子体流的复杂自洽模型， 磁场和电流将完成， 通过与观测值进行比较来约束参数。 在 该模型，偏微分方程求解 在边界层近似数值。 上 从这一模式取得的成果和经验的基础a 更简单的版本，基于常微分方程， 将开发用于并行使用，并耦合 现有模型或正在开发的模型， 关于地球磁场仪计划的内部磁层对流 在层的一侧和外部太阳风等离子体 流在另一边。 这个更简单版本的 边界层模型的基本理论 （一）在第一次世界大战中， 流动方向集成在厚度上， 边界层和（ii）多项式（或其他参数） 跨越边界层的变化的表示， 使用自由参数，允许模型 适应（也许是迭代地）提供的边界条件 通过内部循环模型和外部流 模型 更简单的模型，预计将是 数字上的快速将通过与 自洽边界层代码（这是计算 太慢而不能在GGCM中使用），以及 观测到的电离层和赤道层的特征。