Open AccessComparison between observed and computed polar mesosphere summer echoes
Author(s) -
Klostermeyer J.
Publication year - 1999
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999jd900086
Subject(s) - mesopause , mesosphere , atmospheric sciences , polar , water vapor , saturation (graph theory) , environmental science , computational physics , materials science , physics , meteorology , stratosphere , mathematics , combinatorics , astronomy
A recently developed model for simulating VHF radar signals from the polar summer mesopause region predicts a predominant effect of the temperature on the generation of these so‐called polar mesosphere summer echoes (PMSE). This effect is due to the strongly nonlinear influence of the temperature on the saturation water vapor pressure over ice determining the concentration of ice particles which in turn affects the concentration of free electrons by electron scavenging. In particular, the height and the temperature of the mesopause as well as height regions with enhanced temperature gradients should significantly control the PMSE layer structure whereas other relevant parameters such as the meteoric dust size distribution, the water vapor mixing ratio, and the energy dissipation rate essentially affect the overall echo intensity. In the present study, temperature profiles and radar signal‐to‐noise ratios observed simultaneously in summer 1987 over Andøya (northern Norway) are used for comparing simulated and measured PMSE under the condition of low cosmic noise absorption. In most cases the model reproduces the observed number of PMSE layers as well as the layer heights and widths with accuracies of 1 km, and the deviations between observed and computed maximum signal‐to‐noise ratios do not exceed 10 dB. Since the temperature profiles and the signal‐to‐noise ratios have been measured at distances of about 40 km, at least part of the discrepancies can be attributed to the horizontal nonuniformity of the mesopause region.