Webinar 9 "The Upper Atmosphere"
1. Ionosphere- Introduction and formation 21-01-2019 PPT & VIDEO
2. Ionospheric.... .Variations and Phenomena 22-01-2019 PPT & VIDEO
2. Ionospheric.... .Variations and Phenomena 22-01-2019 PPT & VIDEO
About
the speaker (Prof K N Iyer) Prof. K.N.Iyer did his M.Sc (Physics) and
Ph. D. in 1969 and 1976 from Kerala University and Physical Research Laboratory
(PRL), India respectively. In 1979, he joined Physics Department of Saurashtra
University Rajkot as Reader and later became Professor/Head of the department. His research interests are Ionosphere, Geomagnetism,
Equatorial Electrojet, Equatorial Anomaly, Ionospheric Scintillation, Space
Weather etc. During his academic career of more than 3 decades, he guided 20
Ph.D. and 8 M. Phil students. During 1999-2004 he was in the Editorial Board of
Indian Journal of Radio and Space Physics. He is a reviewer for several International
Journals. He was a visiting scientist at several Space Research Laboratories
e.g. Appleton Lab., UK; ENEA, Rome; and INPE, Brazil. He published more than
100 research papers. He is an elected Fellow of Gujarat Science Academy and
Indian Geophysical Union. Currently he is a visiting faculty of the UN course
on Space and Atmospheric Science (CSSTEAP).
Summary
of each talk is given below:
Talk 1:
Ionosphere- Introduction and formation; 21st January 2019
The classification of the Atmosphere based
on Temperature, Composition and Processes is introduced and the two major
components of the Upper Atmosphere- Thermosphere and Ionosphere - are defined.
Inference about existence of Ionosphere from historic Geomagnetic field
measurements and classical Radio propagation experiments are described and
relevance of Ionosphere for Radio communication emphasized. Chapman’s theory of
Ionospheric production by Photoionization is outlined. Other possible source of
ionization are energetic charged particles. Photochemical Loss processes leading to α –
and β- Chapman layers and resulting electron density in them are also
described.
Talk 2:
Ionospheric Structure Variations and Phenomena; 22nd January 2019
The vertical structure of electron density
leading to the classification of D, E and F regions of the ionosphere and major
positive ions in different regions are described. The ionizing sources for
these regions are shown. Diurnal, seasonal and solar cycle variations of
ionospheric TEC and its day-to- day variability are presented. Interesting
ionospheric phenomena at low and equatorial latitudes are discussed.
Talk 3:
Ionospheric Measurements and Phenomena; 23rd January 2019
Basic concepts of Radio wave propagation
through ionospheric plasma, which form the principles of ionospheric
measurement techniques, are explained. The techniques- Ionosonde, Incoherent Scatter
Radar etc. are outlined and typical results shown. The effects of Phenomena
such as solar flares, and solar eclipse on Ionospheric electron density
profiles are described. More Ionospheric phenomena at equatorial and mid
latitudes are discussed. Examples of peculiar features observed on equatorial
ionograms such as spread-F and sporadic –E are described.
Talk 4:
Ionospheric Coupling with regions above and below; 24th January 2019
The behaviour of
ionosphere is influenced by coupling with neutral atmosphere and driving forces
from below such as gravity waves, tides and drivers from above such as solar
radiations, solar wind, particle precipitation, Magnetospheric electric fields
etc. The associated phenomena such as Ionospheric storms, space weather
effects, Midnight Temperature Maximum, Traveling Ionospheric disturbances are
briefly described. The importance of Electrodynamic Coupling between high and
low latitude ionosphere is also pointed out.