On some effects of upper atmosphere cooling over GWs propagation

SHARON VADAS; MARIANO FAGRE; ANA G. ELIAS; BRUNO S. ZOSSI

Pasadena, California

Congreso; 42nd COSPAR Scientific Assembly; 2018

COSPAR (Committee on Space Research)

The study of cooling and trends in general in the upper atmosphere has gained Interest since the early 1990?s as a consequence of the great concern about the global warming observed in the troposphere. Since then it has become a significant topic in global change investigations. Some research works link these trends to the increase in greenhouse gases concentration, and others to natural causes. Based on many observational and model results a global pattern of trend emerged with the dominant driver of upper atmosphere trends being theincreasing concentration of greenhouse gases. At these heights, a cooling effect is expected, and also observed, together with a decrease in neutral concentration. The propagation of gravity waves (GWs) in the thermosphere depends strongly on neutral temperature and total mass density, so changes should also be expected in GW propagation and dispersion characteristics. Inorder to analyze these changes, a GW ray tracing method, which take into account kinematic viscosity and thermal diffusivity was applied. NRLMSISE-00 and HWM14 models were used to assess the parameters needed for the ray tracing code. As result of decreasing the temperature and neutral density backgroundvalues, the heights reached by the GWs are lower, as expected from theoretical analysis. Although the assessed variations are small, upper atmosphere cooling effect over GWs behavior are a challenging and topical scientific issue worth of deep study and comprehension which can become more noticeable in the futureif the increase in greenhouse gases continues.