Influence of ion outflow in coupled geospace simulations: 1. Physics‐based ion outflow model development and sensitivity study
Influence of ion outflow in coupled geospace simulations: 1. Physics‐based ion outflow model development and sensitivity study
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耦合地球空间模拟中离子流出的影响： 1. 基于物理的离子流出模型开发和灵敏度研究
DOI：
10.1002/2016ja022777
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
J. Lyon
中科院分区：
文献类型：
--
作者：
R. Varney;M. Wiltberger;Binzheng Zhang;W. Lotko;J. Lyon
我们描述了一个耦合的地球空间模型，包括因果调节离子流出基于物理的电离层/极风模型。该模型将多流体里昂-Fedder-Mobarry磁流体动力学（MHD）模型与电离层/极风模型（IPWM）双向耦合。IPWM包括H+和O+极风以及由波粒相互作用（WPI）加速的高能O+的唯象处理。来自MHD模拟的Alfvénic Poynting通量因果地调节离子加速。波粒相互作用（WPI）模型已经过调整，并与粒子模拟和来自快速极光快照卫星数据的经验关系进行了比较。IPWM捕捉了经验关系所遗漏的离子流出的许多方面。首先，整个耦合模型保持了电离层和磁层部分之间的质量，这意味着产生的流出量受到电离层中现实光化学的限制。第二，在强烈的驱动条件下，外流成为电离层所能提供的通量限制。此外，所产生的外流表现出现实的时间和空间延迟相对于磁层能量输入。该耦合模型为研究动态重离子外流对地球空间耦合系统的影响提供了一种灵活的方法。提出的一些示例模拟显示出与流出相关联的内部驱动的振荡，这些振荡的性质在配套文件中进一步分析。
We describe a coupled geospace model that includes causally regulated ion outflow from a physics‐based ionosphere/polar wind model. The model two‐way couples the multifluid Lyon‐Fedder‐Mobarry magnetohydrodynamics (MHD) model to the ionosphere/polar wind model (IPWM). IPWM includes the H+ and O+ polar wind as well as a phenomenological treatment of energetic O+ accelerated by wave‐particle interactions (WPI). Alfvénic Poynting flux from the MHD simulation causally regulates the ion acceleration. The wave‐particle interactions (WPI) model has been tuned and validated with comparisons to particle‐in‐cell simulations and empirical relationships derived from Fast Auroral Snapshot satellite data. IPWM captures many aspects of the ion outflow that empirical relationships miss. First, the entire coupled model conserves mass between the ionospheric and magnetospheric portions, meaning the amount of outflow produced is limited by realistic photochemistry in the ionosphere. Second, under intense driving conditions, the outflow becomes flux limited by what the ionosphere is capable of providing. Furthermore, the outflows produced exhibit realistic temporal and spatial delays relative to the magnetospheric energy inputs. The coupled model provides a flexible way to explore the impacts of dynamic heavy ion outflow on the coupled geospace system. Some of the example simulations presented exhibit internally driven sawtooth oscillations associated with the outflow, and the properties of these oscillations are analyzed further in a companion paper.