New incoherent scatter diagnostic methods for the heated D-region ionosphere

Abstract

Abstract.A new incoherent scatter (IS) diagnostic technique for the actively heated D-region ionosphere is presented. In this approach, an exponential autocorrelation function (ACF) was fitted to the data by using a Markov Chain Monte Carlo (MCMC) inversion and the Sodankylä Ion Chemistry model (SIC). The method was applied for a set of combined EISCAT heating and VHF radar experiments carried out in November 2006. A newly designed radar experiment, sippi, based on optimised phase codes and direct sampling of the transmitted and the received IS signal, was used to produce ACF estimates of the target plasma. Systematic features associated with the heating were found by comparing the mean ACFs corresponding to heated and unheated periods. However, the data analysis revealed reasonable electron temperature estimates at the altitudes of the expected maximum effect (70-75 km) only in three cases out of six, corresponding to the highest signal-to-noise ratio (SNR) conditions. In two of these cases, the electron temperature was increased by a factor of 5 to 7, which is in a good agreement with the theoretical heating modelling. In the case of the first presented data example, the model overestimates the effect. These are the first successful IS observations of the HF-induced maximum electron temperature enhancements in the D-region ionosphere.

Diagnosing radio plasma heating in the polar summer mesosphere using cross modulation: Theory and observations

“…The recent incoherent scatter measurements of D region electron heating by the EISCAT HF facility described by Kero et al [2008] agreed well with a similar type of model to that used here in two of the three cases considered. In the third case, the model overestimated the observed heating, though the authors suggested that this could have been due to contamination of the observations by polar mesospheric winter echoes (PMWE).…”

“…Whilst incoherent scatter radar is capable of determining the electron temperature in the E and F regions [ Evans , 1969], the interpretation of the backscatter spectrum from the D region is complicated. Recently, some progress has been made on this using new techniques [ Kero et al , 2008], but it is desirable to have another method with which to compare these results.…”

Could negative ion production explain the polar mesosphere winter echo (PMWE) modulation in active HF heating experiments?

“…Note that the model is not re‐adjusted to match the data for this particular application. The chemistry parametrization presented in this paper is the same as shown by Kero et al [2008], where the effect of the heating dependent chemistry on the incoherent scatter spectrum was studied.…”

“…The electron density response to the HF heating was parameterized by Kero et al [2008] by using the Sodankylä Ion Chemistry model (SIC) [ Verronen , 2006] extended version 7.2 which solves the concentrations of 36 positive ions, 29 negative ions and 15 minor neutrals via 339 reactions [ Enell et al , 2005]. It should be noted that the negative ion chemistry of the SIC 7.2 is updated to include a revision according to Kazil et al [2003].…”

Fast comparison of IS radar code sequences for lag profile inversion

“…We have shown that the new experiments can be used together with advanced MCMC (Markov Chain Monte Carlo) techniques combined with ionospheric models to do analysis in cases beyond the capabilities of traditional GUISDAP analysis or the lag profile inversion (Kero et al, 2008).…”