Variations in meteor heights at 22.7°S during solar cycle 23

•The relationship between meteor height at 23°S and solar flux has been discussed.•Meteor peak height showed linear decrease of 30–38 m/year when MgII-F10.7 was used.•The behavior of the meteor peak height was in phase with the solar flux.•Meteor echoes are weaker and decay times are reduced during solar minimum years.•Meteor height decrease is thought as being due to a drop in upper atmosphere density.

The meteor radar measurements obtained at Cachoeira Paulista (22.7°S), Brazil, have been used to study a possible relationship between meteor echo height variations and solar flux during solar cycle 23. A good concordance between the normalized values of the annual mean of the meteor peak heights and F10.7 solar radio flux and Mg_II solar indexes have been observed during declining phase of the solar cycle 23. After eliminating the solar activity influence, the annual mean of the meteor echo peak heights showed a linear decrease of 30 m/year when Mg_II solar index is used and 38 m/year when F10.7 solar radio flux is used. When the trend is eliminated the relationship between meteor peak heights and F10.7 solar flux indicate a trend of 672 m/100 sfu (sfu-solar flux unit). The meteor amplitude signals and the decay time drops after mid-2004, which may be attributed to the decreasing of the electron density in the meteor trails. The meteor echo peak height decrease has been interpreted as being caused by a reduction in air density in the upper atmosphere.