SAMI3 data in netCDF format (2019-May-19)

SAMI3 (Sami3 is Also a Model of the Ionosphere) is a seamless, three-dimensional, physics-based model of the ionosphere (Huba et al, 2008). It is based on SAMI2, a two-dimensional model of the ionosphere (Huba et al., 2000). SAMI3 models the plasma and chemical evolution of seven ion species (H⁺, He⁺, N⁺, O⁺, N⁺₂, NO⁺ and O⁺₂). The temperature equation is solved for three ion species (H⁺, He⁺ and O⁺) and for the electrons. Ion inertia is included in the ion momentum equation for motion along the geomagnetic field. This is important in modeling the topside ionosphere and plasmasphere where the plasma becomes collisionless. SAMI3 includes 21 chemical reactions and radiative recombination, and uses a nonorthogonal, nonuniform, fixed grid for the magnetic latitude range +/- 89 degrees.. DriversNeutral composition, temperature, and winds: NRLMSISE00 (Picone et al., 2002) and HWM14 (Drob et al., 2015). Solar radiation: Flare Irradiance Spectral Model version 2 (FISM v2)Magnetic field: Richmond apex model [Richmond, 1995]. Neutral wind dynamo electric field: Determined from the solution of a 2D potential equation [Huba et at., 2008]. For the SAMI3/Weimer configuration: High latitude electric field: calculated from the empirical Weimer model for the potential. For the SAMI3/AMPERE configuration: High latitude electric field: calculated using the Magnetosphere-Ionosphere Coupling solver (MIX) developed by Merkin and Lyon (2010). The inputs to MIX are SAMI3's internal conductances, plus field-aligned current observations from Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), derived from the 66+ satellite Iridium NEXT constellation's engineering magnetometer data. This potential calculation is described in Chartier et al (2022). For ease of use, SAMI3 output is remapped to a regular grid using the Earth System Modeling Framework by Hill et al (2004)

SAMI3（全称Sami3 is Also a Model of the Ionosphere，即电离层模型三号）是一款无缝三维物理驱动电离层模型（Huba等，2008）。其研发基于二维电离层模型SAMI2（Huba等，2000）。SAMI3可模拟7种离子组分（H⁺、He⁺、N⁺、O⁺、N₂⁺、NO⁺及O₂⁺）的等离子体与化学演化过程。针对H⁺、He⁺、O⁺三种离子及电子，模型求解温度方程；在沿地磁场的离子动量方程中纳入离子惯性项，这对模拟无碰撞的顶部电离层与等离子体层场景至关重要。SAMI3包含21种化学反应与辐射复合过程，采用非正交非均匀固定网格，覆盖磁纬度范围±89°。
驱动因子包括：中性大气组分、温度与风场，采用NRLMSISE00（Picone等，2002）与HWM14（Drob等，2015）模型；太阳辐射采用耀斑辐照度光谱模型第2版（Flare Irradiance Spectral Model version 2，FISM v2）；磁场采用Richmond顶点模型（Richmond，1995）；中性风发电机电场通过二维势方程求解得到（Huba等，2008）。
针对SAMI3/Weimer配置，高纬度电场由经验性Weimer势模型计算得到；针对SAMI3/AMPERE配置，高纬度电场通过Merkin与Lyon（2010）开发的磁层-电离层耦合求解器（Magnetosphere-Ionosphere Coupling solver，MIX）计算得到。MIX的输入包括SAMI3内部电导率，以及源自66颗以上铱星Next星座工程磁强计数据的主动磁层与行星电动力学响应实验（Active Magnetosphere and Planetary Electrodynamics Response Experiment，AMPERE）的场向电流观测值。该势场计算方法详见Chartier等（2022）的研究。
为便于使用，SAMI3的输出通过Hill等（2004）开发的地球系统建模框架（Earth System Modeling Framework）重映射至规则网格。