| dc.contributor.advisor | Ramakrishan, S | |
| dc.contributor.author | K B R Prasad | |
| dc.date.accessioned | 2026-03-09T11:58:38Z | |
| dc.date.available | 2026-03-09T11:58:38Z | |
| dc.date.submitted | 1981 | |
| dc.identifier.uri | https://etd.iisc.ac.in/handle/2005/8778 | |
| dc.description.abstract | PhD | |
| dc.language.iso | Doctoral | |
| dc.relation.ispartofseries | T01849 | |
| dc.rights | en_US | |
| dc.subject | This thesis comprises analytical investigations of temperature variations in the 21–60 km altitude region related to solar and geomagnetic activity.
The analyses have been carried out using Meteorological Rocket Network data on stratospheric temperatures obtained during the period from 1969 through 1975 at four selected rocket stations—Port Churchill, Wallops Island, Cape Kennedy, and Fort Sherman—chosen to cover the range of latitudes from high to equatorial. These stations lie in a narrow band of longitudes on the American continent.
The analytical work consists of correlation and linear regression analyses of stratospheric temperatures with solar and geomagnetic indices, and of stratopause height and temperature variations with season, latitude, and solar activity.
The analysis with the sunspot number Rz, the solar 2800 MHz radio flux index F10.7, and the 2000–3100 Å ultraviolet flux at all four Northern Hemisphere stations considered shows a short?term heating effect of solar activity on stratospheric temperatures. This is attributed to enhancements in 2000–3100 Å ultraviolet fluxes during solar activity and absorption of these fluxes by ozone, thereby causing an increase in stratospheric temperatures. This effect is more predominant at the high?latitude station and at high stratospheric altitudes above 45 km.
The analysis using the daily planetary index of geomagnetic activity Ap in relation to the stratospheric temperatures at the four stations indicated two important features. The first is a heating effect on the same day (D?day), whose pattern of latitudinal and altitudinal variations indicates that it is due to the same mechanism of solar UV flux enhancements absorbed by ozone, reflected here through the correlation between geomagnetic and solar indices.
The second feature is a heating effect with a time lag of 4 to 5 days after a day of Ap enhancement at all four stations. This is attributed to long?term circulation disturbances causing a heating effect in the stratosphere. The time lag for the effect is 4 days at the high and mid?latitudes and 5 days at the low and equatorial latitudes.
The analysis of stratopause temperature and height variations shows that the temperatures are highest in summer at the high latitudes and minimum in winter at the high latitudes, while at the equatorial station this pattern is reversed. The stratopause heights are maximum in winter at high latitudes and minimum in summer at the equatorial latitudes.
The analysis with the sunspot number Rz indicates that there is an increase in stratopause temperature with sunspot enhancements, within 24 hours, observed at all four stations. The effect is maximum at the high?latitude station.
The stratopause altitude does not show significant correlation with sunspot number. This can be explained by the inverse temperature dependence of ozone concentration at altitudes above 50 km.
The fact that short?term (of the order of a day) heating effects occur in the stratosphere due to solar activity is an important result obtained in these investigations, which does not appear to have been brought out earlier. This effect should be studied in greater detail. | |
| dc.subject | Stratospheric temperature variations | |
| dc.subject | Solar activity | |
| dc.subject.classification | Indian Institute of Science | |
| dc.title | Effects of solar and geomagnetic activity on stratospheric temperatures | |
| dc.type | Geomagnetic activity | |
| dc.degree.level | Thesis | |
| dc.degree.grantor | I grant Indian Institute of Science the right to archive and to make available my thesis or dissertation in whole or in part in all forms of media, now hereafter known. I retain all proprietary rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation | |
| dc.degree.discipline | Engineering | |
