Meteoroid mass estimation based on single-frequency radar cross section
measurements
Abstract
Both high-power large aperture (HPLA) radars and smaller meteor radars
readily observe the dense head plasma produced as a meteoroid ablates.
However, determining the mass of such meteors based on the information
returned by the radar is challenging. We present a new method for
deriving meteor masses from single-frequency radar measurements, using a
physics-based plasma model and finite-difference time-domain (FDTD)
simulations. The head plasma model derived
in~\citeA{dimopp17} depends on the
meteoroids altitude, speed, and size. We use FDTD simulations of a radar
pulse interacting with such head plasmas to determine the radar cross
section (RCS) that a radar system would observe for a meteor with a
given set of physical properties. By performing simulations over the
observed parameter space, we construct tables relating meteor size,
velocity, and altitude to RCS. We then use these tables to map a set of
observations from the MAARSY radar (53.5 MHz) to fully-defined plasma
distributions, from which masses are calculated. To validate these
results, we repeat the analysis using observations of the same meteors
by the EISCAT radar (929 MHz). The resulting masses are strongly
linearly correlated; however, the masses derived from EISCAT
measurements are on average 1.33 times larger than those derived from
MAARSY measurements. Since this method does not require dual-frequency
measurements for mass determination, only validation, it can be applied
in the future to observations made by many single-frequency radar
systems.