Physics of auroral phenomena : proceedings of the 34th Annual seminar, Apatity, 01 - 04 March, 2011 / [ed.: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 231 с. : ил.

L.L. Lazutin, Т. V. Kozelova SER V IS -1 ,10 -1 2 .02 .2004 Fig 2. Plots o f the 0.3 MeV electron intensity atfixed L during February 11, 2004 magnetic storm, evening orbits. Figure 1 shows Dst-index and H-component of the magnetogramm of the Chokurdakh observatory which was at that time in a local night - early morning sector. Three activations can be identified at the magnetogramm, with the biggest one started at ~ 17.20 UT and reached magnetic bay minimum (-lOOOnT) at ~ 17.40 UT. Figure 2 presents electron intensity temporal development measured at three L -levels from L=3 to L=4. Electron intensities were measured on down part of the satellite orbit. We are using here all data, two L- profiles per 90 minutes of each satellite orbit. During one day satellite pass several times over Brazilian (South Atlantic) Magnetic Anomaly (BMA) where satellite trajectory enters the radiation belt cusp. During other orbits only precipitating particles can be measured at satellite altitude. Before the beginning of the magnetic storm difference between trapped particle Fig 3. Latitudinal profdes o f the 0.3 MeV electrons during February 11, 2004 magnetic storm. Time o f satellite crossings o fL=4 are indicated. intensity measured over BMA and precipitating ones on other longitudes is clearly seen. For example on February 10 at the L=3 around 06 UT when satellite at the morning sector registered electron flux over BMA it exceeds by one order the precipitating flux near 18 UT. But this difference became smaller with increase of particle intensity, which allows to follow fast electron flux variations with time resolution less than one hour. The most pronounced effect reflected by Figure 2 is a fast electron increase observed at the end of the storm main phase on L=3 to 4 at 17.36 UT, which coincides remarkably with substorm activation. It was not created by some impulsive intensification of the precipitating particle flux, but increase of the trapped particle flux as well, because an enhanced intensity level was observed until the end of the magnetic storm. Examples of the latitudinal profiles (or L-profiles) are shown on Figure 3. Time marks near the plots indicate L=4 crossing. First profile was measured just at the beginning of the storm main phase, two other near the end of the main phase and all four during the substorm activity. One can see considerable variability of the L- profiles and effect of the erosion of the electron intensity at the end of the main phase at L > 4.2. One of three substorms registered by magnetometer caused increase on L=4 and does not changed electron intensity on L=3.5 (Figure 3, profile 15.53 UT). Large earthward shift of the electron profile was registered at 17.36 UT and as it was said before exactly coincide with the sharp slope o f the magnetic bay and, consequently with substorm activation. This shift creates intensity increase at the maximum of the radiation belt and more than tenfiold increase at L=3 and 3.5 level as seen on Figure 2 and 3. In 1.7 MeV energy channel fast intensity increase was not observed. electrons, 0.5 MeV, Februory 11, 2004 : 17.36 UT 12.40 UT 18