Polar mesosphere summer echoes (PMSE) at Halley (76°S, 27°W), Antarctica

Polar Mesosphere Summer Echoes (PMSE) are a pointer to summer mesospheric conditions and have fuelled the debate over temperature differences between the Antarctic and Arctic mesopause regions. However few PMSE observations have ever been made in Antarctica. We present initial PMSE observations from Halley (76°S, 27°W), taken during January and February 2004. These are the first observations at such high southern latitude, the first using a dynasonde for detection, and the first at 28 MHz. PMSE are frequently observed and exhibit a double maximum in diurnal occurrence in contrast to published observations at similar Arctic latitudes. The PMSE season ends slightly earlier, relative to summer solstice, than in the Arctic. The strength of the PMSE appear similar to PMSE observed in the northern hemisphere; this is consistent with published falling sphere measurements showing similar summer mesopause temperatures in January in the Antarctic as in July in the Arctic.