A Comparative Study of Heating Effects on PMSE between the Naturally Occurred Mono Double and Tri Layers.

One of the remarkable properties of Polar Mesosphere Summer Echoes (PMSE) is their occurrence in the form of distinct multiple layers (double- and tri-layers). Using the PMSE observations of E-ISCAT VHF radar, for the first time, we present a combination of heating with multiple layers. Our main focus is to compare the heating effects between the mono-, double-, and tri-layers. Our results show that, as compare to mono-layer, PMSE is greatly affected by HF heating in multiple layers. As a result, the modulated characteristics (e.g., PMSE intensity reduction, recovery, and overshoot) produced in multiple layers are greater than those in mono-layer. Inside multiple layers, the PMSE heating decreases with increasing altitude. Due to heating, the enhancement produced in electron temperature is estimated which is also greater in multiple layers than those in mono-layer. The considerable increase in electron temperature may be one of the possible reasons for the strong heating effects in multiple layers. In addition, we show the dependency of the PMSE heating on the HF pump parameters (effective radiated power (ERP), polarization, frequency, and heating cycle time). It is found that in all layers, the PMSE heating increases with increasing ERP. X-mode and O-mode polarizations produce strong heating in mono-layer and in multiple layers, respectively. We found no significant effect of Heater frequency on PMSE heating. The heating cycle time is the sum of Heater on and off times. In both, mono- and multiple layers, the increasing Heater on time does not greatly affect the PMSE heating, on the other hand, the increasing Heater off time significantly increases the PMSE overshoot effect. [ABSTRACT FROM AUTHOR]