Global modeling of hot O distribution in the upper thermosphere

Abstract

The existence of hot oxygen (hot O, O h ) in the upper thermosphere is mainly confirmed by optical observations of high-altitude airglow. In the experiments described here, a peak of O h population was found at an altitude of approximately 550 km with a temperature of about 4000 K. Although it was shown that O h concentration could reach a value of 1-2% with respect to ambient (cold) O, a realistic global distribution of O h concentration and temperature has not been established. The presence of non-thermal atoms in the thermosphere leads to variations in the thermo-dynamical regime in the upper atmosphere. The major chemical processes involved in O h production were taken into account in the time-dependent, Global Self-consistent Model of Thermosphere, Ionosphere and Protonosphere (GSM TIP) of the Earth in order to simulate global distribution of O h concentration and temperature (T h ). Calculations were carried out in the geomagnetic coordinate system for moderate solar, quiet geomagnetic conditions, and winter season. It was shown that the maximum O h is located at −60• latitude, 300• longitude, and 24 UT. The T h maximum is about 2050 K. This temperature and O h concentration cause an increase in neutral gas temperature at high thermosphere by ∼100 K during daytime and by ∼70 K during nighttime. Variations in the neutral gas velocity circulation were calculated. The maximum increase in neutral velocity was about 36 m/s, corresponding to = 50• , = 180• in the northern and = −50• , = 270• in the southern hemisphere.

The global thermospheric and ionospheric response to the 2008 minor sudden stratospheric warming event

“…The transformations between all coordinate systems in the model are given by standard equations. The GSM TIP model were described in detail by Namgaladze et al [1988, 1991], and its recent modifications were presented in Klimenko et al [2006, 2007, 2011a], and Bessarab and Korenkov [2011]. The GSM TIP has been used to study the dynamic forcing of the thermosphere ‐ ionosphere system from below [ Karpov and Bessarab , 2008; Namgaladze et al , 2009; Klimenko et al , 2011b, 2012; Bessarab et al , 2012].…”

Study of the thermospheric and ionospheric response to the 2009 sudden stratospheric warming using TIME‐GCM and GSM TIP models: First results

“…This ionospheric part of the code has variable spatial steps along the magnetic field lines. The GSM TIP model was described in detail by Namgaladze et al [1988], and its recent modifications were presented in Korenkov et al [1998], Klimenko et al [2007Klimenko et al [ , 2011a, and Bessarab and Korenkov [2011]. The GSM TIP has been used to study the dynamic forcing of the thermosphere-ionosphere system from below [Karpov and Bessarab, 2008;Klimenko et al, 2011bKlimenko et al, , 2012 and recently to study the global thermospheric and ionospheric response to 2008 and 2009 SSW events [Bessarab et al, 2012;Korenkov et al, 2012].…”