Similarities and differences in polar mesosphere summer echoes observed in the Arctic and Antarctica

Abstract

Abstract. Polar Mesosphere Summer Echoes (PMSE) have been observed in the high latitudes of the Northern and Southern Hemisphere for several years using VHF radars located at Andenes/Norway (69 • N, 16 • E), Resolute Bay/Canada (75 • N, 95 • W), and Davis/Antarctica (69 • S, 78 • E). The VHF radars at the three sites were calibrated using the same methods (noise source and delayed transmitting signal) and identical equipment. Volume reflectivity was derived from the calibrated echo power and the characteristics of the seasonal variation of PMSE were estimated at the sites for the years 2004 to 2007. The largest peak volume reflectivity of about 2×10 −9 m −1 was observed at Andenes compared with their counterparts at Davis (∼4×10 −11 m −1 ) and Resolute Bay (∼6×10 −12 m −1 ). The peak of the PMSE height distribution is 85.6 km at Davis which is about 1 km higher than at Andenes. At Resolute Bay the height distribution peaks at about 85 km but only a few layers were found below 84 km. The mean PMSE occurrence rate is 83% at Andenes, 38% at Davis with larger variability and only 18% at Resolute Bay (in late summer). The duration of the PMSE season varies at Andenes from 104 to 113 days and at Davis from 88 to 93 days. In general the PMSE seasons starts about 5 days later at Davis and ends about 10 days earlier compared to Andenes. In all three seasons the PMSE occurrence suddenly drops to a much lower level at Davis about 32 days after solstice whereas the PMSE season decays smoothly at Andenes. The duration of the PMSE season at Andenes and Davis is highly correlated with the presence of equatorward directed winds, the observed differences in PMSE occurrence are related to the mesospheric temperatures at both sites.

Response of polar mesosphere summer echoes to geomagnetic disturbances in the Southern and Northern Hemispheres: the importance of nitric oxide

“…This seemed to be consistent with the (limited) information then available, suggesting that summer mesopause temperatures at about 70 • latitude were about the same in both hemispheres (Lübken et al, 1999). Nilsson et al (2008) compared PMSE between Wasa and Davis, Antarctica (69 • S, 78 • E), and found about half the occurrence rates at Davis compared to Wasa, which was consistent with satellite indications of temperature differences at the time of those measurements between 69 • S and 73 • S. Latteck et al (2008) , and found occurrence rates of 18 %, 83 % and 38 %, respectively, with mean and maximum reflectivities also varying in the same order. For the same time interval, and the same detection threshold, Smirnova et al (2010) found about a 75 % occurrence rate at Kiruna, which gives a consistent difference between Andenes/Kiruna/Wasa (all about the same) and Davis.…”

Spatial and temporal variability in MLT turbulence inferred from in situ and ground-based observations during the WADIS-1 sounding rocket campaign

“…Figure 3 shows a height-time intensity plot of radar volume reflectivity observed by the vertical beam of MAARSY. The volume reflectivity was converted directly from the absolute value of the received signal power as described in Latteck et al (2008). The vertical magenta line marks the WADIS-1 launch time when MAARSY was detecting a double-layered structure.…”

The Geminid meteor shower during the ECOMA sounding rocket campaign: specular and head echo radar observations

“…A detailed list of the experimental parameters is given in Table 1. In addition to these standard meteor experiments both radars were calibrated using the delay line method (Latteck et al, 2008). This permits to directly quantify the observed electron line densities in order to estimate the meteoroid size/mass assuming single body meteor ablation.…”