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- Title
A Model of High Latitude Ionospheric Convection Derived From SuperDARN EOF Model Data.
- Authors
Lam, M. M.; Shore, R. M.; Chisham, G.; Freeman, M. P.; Grocott, A.; Walach, M.‐T.; Orr, L.
- Abstract
Forecasting of the effects of thermospheric drag on satellites will be improved significantly with better modeling of space weather effects on the high‐latitude ionosphere, in particular the Joule heating arising from electric field variability. We use a regression analysis to build a model of the ionospheric convection drift velocity which is driven by relatively few solar and solar wind variables. The model is developed using a solar cycle's worth (1997–2008 inclusive) of 5‐min resolution Empirical Orthogonal Function (EOF) patterns derived from Super Dual Auroral Radar Network (SuperDARN) line‐of‐sight observations of the convection velocity across the high‐latitude northern hemisphere ionosphere. At key stages of development of the model, we use the percentage of explained variance P to see how well the model reproduces the EOF data. The final model is driven by four variables: (a) the interplanetary magnetic field component By, (b) the solar wind coupling parameter epsilon ε, (c) a trigonometric function of day‐of‐year, and (d) the monthly F10.7 index. The model can reproduce the EOF velocities with a characteristic P = 0.7. The model and EOF data compare best around the solar maximum of 2001. P $P$ is lower around solar minimum, due to occasional limitations in the geographical and temporal coverage of the SuperDARN measurements. This may indicate the need to modify our model around the minimum of the solar cycle. Our model has the potential to be used to forecast the ionospheric electric field using the real‐time solar wind data available from spacecraft located upstream of the Earth. Plain Language Summary: Variations in space weather in the ionized region of the Earth's atmosphere (the ionosphere) can result in expansion of the atmosphere, increasing the atmospheric drag on objects, such as satellites, in the thermosphere. We aim to significantly improve the forecasting of the effects of atmospheric drag on satellites by more accurate modeling of space weather effects on the motion of ionized particles (plasma) in the ionosphere. We have developed a model of the variation in plasma motion using a few solar wind variables which are all now available in real time from satellites upstream of the Earth. The model was built using 5‐min resolution observations of the ionospheric plasma motion from a 12‐year interval, to capture effects on the solar cycle timescale. Our model is good at reproducing the original data set—if 0 indicates that there is no reproduction and 1 indicates exact reproduction, then our model scores 0.7. Data set reproduction is best around the maximum in the solar cycle and worst at solar minimum. This is mainly due to differences in the spatiotemporal data coverage between these times but possibly also the model's specification of the physical processes coupling the Sun to the Earth's ionosphere. Key Points: We present a regression model of high‐latitude ionospheric plasma convection driven by a small number of space weather variablesThe model could be a valuable tool for operational forecasting due to its simplicityThe model reproduces its parent data set best around solar maximum, with a mean percentage of explained variance of 0.7 over 12 years
- Subjects
THERMOSPHERE; SOLAR wind; INTERPLANETARY magnetic fields; SPACE environment; SOLAR cycle; IONOSPHERIC plasma; PARTICLE motion
- Publication
Space Weather: The International Journal of Research & Applications, 2023, Vol 21, Issue 7, p1
- ISSN
1539-4956
- Publication type
Article
- DOI
10.1029/2023SW003428