Ondrejov radar observations of Leonid shower activity in 2000-2002

Results of Ondrejov radar observations of the Leonid meteor shower in 2000, 2001 and 2002 are presented. Three years of observations covered the solar longitude interval of shower activity from 234.degrees85 to 237.degrees25 (J2000.0). The shower activity in 2000 and 2001 spread over two days while in 2002 over only a few hours during one day. The highest activity level was detected in 2002 and the lowest one in 2001. No activity of underdense radiometeors was registered in 2001. From all studied years the 2002 activity expressed in 30-min rates of overdense echoes was richest in comparison with corresponding rates in remaining years. The activity curves in 2000 and 2001 consisted of many peaks of widely fluctuating character while the corresponding curve in 2002 was formed by only one well pronounced maximum followed by one secondary one. One of the smaller peaks in 2000 at L-circle dot = 236.degrees11 (4h15m UT on Nov. 18) appeared also in 2001 at the same solar longitude (10h15m UT on Nov. 18) as the strongest maximum in this year. Comparison of the mass distribution indices, s, computed from overdense echo rates (registered within main activity peaks) showed that they were lowest in 2000 when they approached s similar or equal to 1.13 while they were highest in 2002 when s similar or equal to 1.22 indicating that the proportion of fainter meteors in the observed data sample increased from 2000 to 2002. We have compared the activity with predictions from the literature. We have confirmed a few peaks predicted although they were not always produced by meteors of all four echo categories we defined. This corresponds to different activity of meteoroids of different masses. Moreover, we have also found remarkable activity on Nov. 19, 2001 which was not predicted.