## 2 Methods and Data  
### Data  
The NOAA project of the polar operational environmental satellite (POES) has been successfully operating for more than 25 years. The satellites have a polar sun-synchronous orbit. The NOAA/POES and MetOp constellation monitors radiation conditions at low altitudes (\(\sim\)850 km), in particular below the inner ERB. The maximum number of satellites in the constellation reached 7 in 2012, and by 2025, 5 satellites are operating in orbit. The data on particles from 2009 are available at [[https://www.ncei.noaa.gov/data/](https://www.ncei.noaa.gov/data/)]([https://www.ncei.noaa.gov/data/](https://www.ncei.noaa.gov/data/)) (accessed on 4 July 2025). Methods of identification of FEE enhancements and selection of FEE-events are described in details in [4; 6]. The energetic electrons are measured by the MEPED telescope [40], which includes electron detectors (\(>\)30, \(>\)100, and \(>\)300 keV). Since 2014, the thresholds of the integral channels have been refined in the technical documentation (\(>\)40, \(>\)130, \(>\)290 keV). In this paper, we will use the old designation. Pairs of detectors with an orthogonal orientation allow simultaneous measuring of the fluxes of quasi-trapped and precipitating particles. The FEE enhancements are observed only in the quasi-trapped electron population near and at the equator, not in the precipitating population [2]. Quasi-trapped particles are those in the drift loss cone, because such particles are inevitably lost (precipitated) in the SAA during one azimuthal drift period (hours). Whereas precipitating particles are in the bounce loss cone, their lifetime is limited to one bounce period (seconds). We have found from observations that electron precipitating fluxes do not enhance at the geomagnetic equator during the FEE-events (e.g., [7]). In the current work, we analyze total pressure \(P\) of the solar wind and orientation of the interplanetary magnetic field (IMF). Solar wind plasma parameters (flow velocity \(V\), proton density \(D\), and temperature \(T\), helium contribution) and magnetic field (strength \(B\) and components \(Bx\), \(By\), and \(Bz\)) are measured by the ACE or Wind monitors positioned at the first Lagrangian Point (L1). The data on interplanetary parameters are available at [[https://cdaweb.gsfc.nasa.gov](https://cdaweb.gsfc.nasa.gov)]([https://cdaweb.gsfc.nasa.gov](https://cdaweb.gsfc.nasa.gov)) (accessed on 4 July 2025). The total pressure \(P\) is calculated as the sum of the dynamic, thermal and magnetic pressures, where the dynamic pressure also includes the contribution of helium ions (measured or 4% of protons density) [41]:  
\[P=mDV^{2}\bigg{(}1+4\frac{He}{H}\bigg{)}+kTD+\frac{B^{2}}{2\mu_{0}} \tag{1}\]  
where \(m\) is atom mass of proton, \(He/H\) is a helium-proton ratio (if not measured, then the average value of 0.04 was taken), \(k\) is Boltzmann constant, \(\mu_{0}\) is vacuum magnetic permeability. Here \(P\) is expressed in terms of SI base units and has the unit Pascal (Pa). In the units commonly used for magnetospheric physics, the magnetic field \(B\) is in nT, \(T\) in eV, \(D\) in cm\({}^{-3}\), and \(V\) in km/s. Then the pressure \(P\) is expressed in nPa and calculated as:  
\[P=1.67\cdot 10^{-6}\cdot DV^{2}\bigg{(}1+4\frac{He}{H}\bigg{)}+1.6\cdot 10^{-4} \cdot DT+3.98\cdot 10^{-4}\cdot B^{2} \tag{2}\]  
We use geomagnetic indices and ground magnetic field measurements to further correct the propagation timing of solar wind structures moving at the plasma flow velocity from L1 to the Earth. Geomagnetic activity indices and geomagnetic horizontal H or X components are measured on the ground network of magnetometers SuperMAG and INTERMAG ([[https://supermag.jhuapl.edu/](https://supermag.jhuapl.edu/)]([https://supermag.jhuapl.edu/](https://supermag.jhuapl.edu/)), accessed on 4 July 2025 and [[https://intermagnet.org/](https://intermagnet.org/)]([https://intermagnet.org/](https://intermagnet.org/)), accessed on 4 July 2025).