Radar efficiency and the calculation of decade-long PMSE backscatter cross-section for the Resolute Bay VHF radar

Abstract

Abstract. The Resolute Bay VHF radar, located in Nunavut, Canada (75.0 • N, 95.0 • W) and operating at 51.5 MHz, has been used to investigate Polar Mesosphere Summer Echoes (PMSE) since 1997. PMSE are a unique form of strong coherent radar echoes, and their understanding has been a challenge to the scientific community since their discovery more than three decades ago. While other high latitude radars have recorded strong levels of PMSE activities, the Resolute Bay radar has observed relatively lower levels of PMSE strengths. In order to derive absolute measurements of PMSE strength at this site, a technique is developed to determine the radar efficiency using cosmic (sky) noise variations along with the help of a calibrated noise source. VHF radars are only rarely calibrated, but determination of efficiency is even less common. Here we emphasize the importance of efficiency for determination of cross-section measurements. The significant advantage of this method is that it can be directly applied to any MST radar system anywhere in the world as long as the sky noise variations are known. The radar efficiencies for two on-site radars at Resolute Bay are determined. PMSE backscatter cross-section is estimated, and decade-long PMSE strength variations at this location are investigated. It was noticed that the median of the backscatter cross-section distribution remains relatively unchanged, but over the years a great level of variability occurs in the high power tail of the distribution.

Long-term aspect-sensitivity measurements of polar mesosphere summer echoes (PMSE) at Resolute Bay using a 51.5MHz VHF radar

“…Recently the radar system was absolutely calibrated using cosmic noise variations with the additional help of a commercially available calibrated noise source Hocking, 2006, 2007). This allowed us to express the absolute signal strength of PMSE at this location in terms of backscatter cross-sections (Swarnalingam et al, 2009a). The radar has been properly maintained.…”

Aspect sensitivity of polar mesosphere summer echoes based on ESRAD MST radar measurements in Kiruna, Sweden in 1997–2010

“…Finally, we found that we underestimated volume reflectivity of at least half of PMSE (those which are aspect sensitive) detected with ESRAD by factor of 1.6-2.3 (by 2-3.5 dB). For comparison, Swarnalingam et al (2009a) reported 0.3 dB possible effect due to high aspect sensitivity (5 • ) evaluated for the Resolute Bay VHF radar with 1.4 • two-way radar beam width.…”

Spectral characteristics and scatter cross-section of low latitude mesospheric echoes measured by the Indian MST radar at Gadanki

“…Kirkwood et al, 2007;Swarnalingam et al, 2009). Calibration of the Indian MST radar receive path was accomplished using the daily variation of galactic noise and direct signal injection tests in January 2010 (Kirkwood et al, 2010).…”