Thermospheric Temperature and Density Variability During 3 to 4 February
2022 Minor Geomagnetic Storm: The SpaceX Satellite Loss Event
Abstract
Themospheric conditions during a minor geomagnetic event of 3 and 4
February 2022 has been investigated using disk temperature
(T$_{disk}$) observations from Global-scale Observations of the
Limb and Disk (GOLD) mission and model simulations. GOLD observed that
the T$_{disk}$ increases by more than 60 K during the storm event
when compared with pre-storm quiet days. A comparison of the
T$_{disk}$ with effective temperatures (i.e., a weighted average
based on airglow emission layer) from Mass Spectrometer Incoherent
Scatter radar version 2 (MSIS2) and Multiscale Atmosphere-Geospace
Environment (MAGE) models shows that MAGE outperforms MSIS2 during this
particular event. MAGE underestimates the T$_{eff}$ by about
2\%, whereas MSIS2 underestimates it by
7\%. As temperature enhancements lead to an expansion of
the thermosphere and resulting density changes, the value of the
temperature enhancement observed by GOLD can be utilized to find a GOLD
equivalent MSIS2 (GOLD-MSIS) simulation $\textendash$
from a set of MSIS2 runs obtained by varying geomagnetic ap index
values. From the MSIS2 runs we find that an ap value of 116 nT produces
a T$_{eff}$ perturbation that matches with the GOLD T$_{disk}$
enhancement. Note that during this storm the highest value of the 3 hr
cadence ap was 56 nT. From the MSIS-GOLD run we found that the
thermospheric density enhancement varies with altitude from
15\% (at 150 km) to 80\% (at 500 km).
Independent simulations from the MAGE model also show a comparable
enhancement in neutral density. These results suggest that even a modest
storm could impact the thermospheric densities significantly.