We have investigated properties such as speed, angular width, location, acceleration and occurren... more We have investigated properties such as speed, angular width, location, acceleration and occurrence rate of narrow CMEs (defined as having angular width ≤20°) observed during 1996–2007 by SOHO/LASCO. The results obtained are compared with those of normal CMEs (angular width >20°) from the same time interval to find whether there are any real differences between the two populations. Our study of 3464 narrow CMEs from the online SOHO/LASCO, CME catalogue leads us to conclude that (1) the fraction of narrow CMEs during solar minimum is 38% and during solar maximum 19%, (2) during solar maximum narrow CMEs are generally faster than normal CMEs, (3) the maximum speed of narrow CMEs is much smaller than that of the normal CMEs, (4) during solar maximum narrow CMEs appear at all latitudes similar to normal CMEs, (5) narrow and normal CMEs have unequal deceleration and (6) the occurrence rate of narrow CMEs remain constant after 1998 until the beginning of 2006 while the normal CMEs occurrence rate seems to follow solar cycle variation until 2004. Thus narrow CMEs and normal CMEs have some differences, in disagreement with previous studies.
We have studied properties of the radio-rich coronal mass ejections (CMEs) (observed during 1997–... more We have studied properties of the radio-rich coronal mass ejections (CMEs) (observed during 1997–2006) which produce type II (1–14 MHz) i.e. decametric–hectometric or DH radio burst. These DH CMEs are relatively faster and wider than the normal CMEs. The average speed and apparent width of these CMEs is 1048 km/s and 98°, respectively. Majority (about 54%) of DH CMEs decelerate, but about 21% show positive acceleration. The remaining 25% move with little acceleration. These special characteristics of radio-rich CMEs could be used to identify the population of geoeffective CMEs, which are quite relevant to space weather.
We have investigated properties such as speed, angular width, location, acceleration and occurren... more We have investigated properties such as speed, angular width, location, acceleration and occurrence rate of narrow CMEs (defined as having angular width ≤20°) observed during 1996–2007 by SOHO/LASCO. The results obtained are compared with those of normal CMEs (angular width >20°) from the same time interval to find whether there are any real differences between the two populations. Our study of 3464 narrow CMEs from the online SOHO/LASCO, CME catalogue leads us to conclude that (1) the fraction of narrow CMEs during solar minimum is 38% and during solar maximum 19%, (2) during solar maximum narrow CMEs are generally faster than normal CMEs, (3) the maximum speed of narrow CMEs is much smaller than that of the normal CMEs, (4) during solar maximum narrow CMEs appear at all latitudes similar to normal CMEs, (5) narrow and normal CMEs have unequal deceleration and (6) the occurrence rate of narrow CMEs remain constant after 1998 until the beginning of 2006 while the normal CMEs occurrence rate seems to follow solar cycle variation until 2004. Thus narrow CMEs and normal CMEs have some differences, in disagreement with previous studies.
We have studied properties of the radio-rich coronal mass ejections (CMEs) (observed during 1997–... more We have studied properties of the radio-rich coronal mass ejections (CMEs) (observed during 1997–2006) which produce type II (1–14 MHz) i.e. decametric–hectometric or DH radio burst. These DH CMEs are relatively faster and wider than the normal CMEs. The average speed and apparent width of these CMEs is 1048 km/s and 98°, respectively. Majority (about 54%) of DH CMEs decelerate, but about 21% show positive acceleration. The remaining 25% move with little acceleration. These special characteristics of radio-rich CMEs could be used to identify the population of geoeffective CMEs, which are quite relevant to space weather.
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Papers by Nishant Mittal