Comparison of atmospheric parameters derived from meteor observations with CIRA

Abstract

Our results are complimentary to those of Hocking et al.; our data were obtained in the Southern Hemisphere as opposed to the Northern Hemisphere. A discussion on the effect of the geomagnetic field on the diffusion of meteor trails and its effect on the measurement of atmospheric parameters is also included. We note that the geomagnetic field is a very important consideration when using meteors for the derivation of atmospheric temperatures and pressures above heights of around 92-93 km. This effect is required to be taken into account above these heights as failure to do so leads to errors in the interpretation of the data. Recent researchers have avoided this problem by restricting their data to below 90 km.

Observations on Stratospheric-Mesospheric-Thermospheric temperatures using Indian MST radar and co-located LIDAR during Leonid Meteor Shower (LMS)

“…Since the temperature from the meteor trail diffusion rate was estimated assuming CIRA-86 model neutral densities and molecular weights, any uncertainties in these two parameters additively deviate the temperature estimated, for example, the combined ±20% (as it is normally found with CIRA-86 model) uncertainty appearing in these two parameters would bring an amount of ±40 K difference for a temperature of 200 K. On the other hand, if an error occurs in the calculation of τ 1/2 , it is only about ±0.4% of the estimated temperature, since the time resolution is 4 ms in our experiment. Further, the variability of ±0.075 m 2 /s in the diffusion coefficient over a base value of 0.275 m 2 /s at 90 km where the maximum meteor fall, also known as mean meteor peak height, was registered and accounts for the uncertainty of ±15-20 K in the estimated temperature of 200 K. In fact, the range of diffusion coefficient for a given height is seen to be much narrower in our case compared to the previous results reported in literature (Hocking, 1999;Cervara and Reid, 2000;Hocking, 2001). Perhaps, the less variance observed could be characteristic of equatorial MLT region.…”

Change in turbopause altitude at 52 and 70° N

“…where P is the neutral pressure and K 0 is the zero field mobility of the ions in the trail (here we assume , 1961;Chilson et al, 1996;Cervera and Reid, 2000;Holdsworth et al, 2006). The pressure, P , was obtained from NRLMSISE-00 for consistency with the turbulence calculations.…”

Neutral atmosphere temperature trends and variability at 90 km, 70 °N, 19 °E, 2003–2014

“…For calculations of temperatures using meteor radar, ambipolar diffusion alone is assumed to determine the decay of the underdense echoes. Diffusivities are expected to increase exponentially with height through the region from which meteor echoes are obtained (Ballinger et al, 2008;Chilson et al, 1996). Hall et al (2005) find that this is only the case between ∼ 85 and ∼ 95 km altitude, using diffusion coefficients delivered by NTMR from 2004.…”