Abstract
Abstract. Simultaneous measurements of temperature and polar mesosphere summer echoes (PMSE) were performed at the polar cap (78° N) during summer 2001 and 2003. In summer time the mesopause region is characterized by extremely low temperatures around 120 K. It is remarkable that PMSE are practically never observed above 92 km although temperatures are low enough to allow the existence of ice particles. In this case study we compare the PMSE topside with temperatures measured by the potassium lidar and with frost point temperatures using water-vapor mixing ratios from models. We find striking discrepancies with our current understanding of ice particles and temperature in this region. In this case study we find that the temperature can be more than 20 K lower than the frost point temperature but no PMSE is observed above 92 km altitude. We show that the lack of PMSE does not necessarily imply that the temperature is too high.
Highlights
Remote sensing of layers in the upper mesosphere can provide important information about the thermal and dynamical background conditions in a part of our atmosphere which is experimentally difficult to access
In this case study we find that the temperature can be more than 20 K lower than the frost point temperature but no polar mesosphere summer echoes (PMSE) is observed above 92 km altitude
The radar sensitivity of the SOUSY Svalbard Radar (SSR) is comparable or even slightly larger than that of the ALWIN VHF radar (Latteck et al, 1999, 2005). The latter has been absolutely calibrated by Latteck et al (2005) who showed that ALWIN possess sufficient sensitivity to observe PMSE
Summary
Remote sensing of layers in the upper mesosphere can provide important information about the thermal and dynamical background conditions in a part of our atmosphere which is experimentally difficult to access. One important example of such layers are so-called “polar mesosphere summer echoes” (PMSE) This phenomenon is related to ice particles which can only exist at these altitudes if the temperature is less 120–150 K. Stand of the relationship between the thermal structure of the mesopause region and the existence of these ice particles This is important since the lack of PMSE is often automatically interpreted the temperature being too high or the water vapor concentration being to low; leading to further interpretations. PMSE are very strong radar echoes at the radar half wavelength (i.e. Bragg scale) received from the summer mesopause region at polar latitudes They were first observed in the late 1970s by radars in the VHF band (Czechowsky et al, 1979; Ecklund and Balsley, 1981). PMSE require the presence of ice particles and supersaturation conditions, i.e
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