Concurrent Observations of Meteor Head Echo Populations at Multiple High-Power Radar Facilities

On October 10th and 11th, 2019, concurrent high-power large-aperture (HPLA) meteor radar observations were performed at varying latitudes and similar longitudes at Resolute Bay Incoherent Scatter Radar (RISR-N), Jicamarca Radio Observatory (JRO), and MIT Haystack Observatory (MHO), with the goal to eliminate diurnal, seasonal, and solar cycle biases in the observed meteor populations and study latitudinal coupling of neutral densities in the upper atmosphere. Concurrent observations spanned 8 hours, with thousands of meteor head echos observed at each facility. In this poster, an inter-pulse phase differencing technique for head echos is proven to consistently reduce uncertainty in the range rate (velocity component along radar beam) by an order of magnitude versus rates obtained via Doppler shifts at individual pulses. The algorithm depends on removing discontinuities due to the 2 pi modulo in the phase change of the complex meteor signal between pulses, which can be done very reliably by inspection, and somewhat reliably via an automated procedure. The resulting range rates are smooth enough that exponential fits yield reasonably accurate range decelerations. The meteor populations at each facility are presented and compared. A clear trend of greater decelerations at lower altitudes is observed, as expected given increased drag where the atmosphere is denser. Because RISR-N is near the North Pole and points away from the ecliptic plane, it does not observe meteors with range rates faster than 55 km/s. At JRO near the equator, a larger spread of range rates is observed. The RISR-N meteor population demonstrates a bias toward larger and faster meteors due to its higher carrier frequency, unlike JRO. However, the higher carrier frequency at RISR-N enables greater accuracy in its deceleration measurements. Future work will utilize decelerations at all three facilities to quantify neutral densities as a function of latitude and altitude.