Analysis of plasma bubbles observed in night airglow emission line OI 630.0 nm from Kolhapur using all sky imager

Abstract

All-sky imager (ASI) located at Kolhapur (16.8º N, 74.2º E), India is used to observe OI 630.0 nm night airglow emission (at an altitude 250 km) during clear moonless nights. To study the characteristics of night airglow variations we have taken one month (February 2012) imager data of OI 630.0 nm emission line. The plasma bubbles have their own internal space-time dynamics [13] therefore result shows temporal variability in plasma motion. Due to change in the shape and size of plasma bubble some errors may occur in determination of the plasma velocity. So the reference of the western, eastern and middle wall/edge of the plasma bubble had been taken into account for calculating its velocity. The OI 630.0 nm emission having north–south aligned intensity depletion bands propagated from west to east with average velocity ~ 140 m/s. We found that the initially the plasma velocity is high and it decreases with time.