Articles | Volume 25, issue 8
https://doi.org/10.5194/angeo-25-1759-2007
https://doi.org/10.5194/angeo-25-1759-2007
29 Aug 2007
 | 29 Aug 2007

Lidar observations of sporadic Na layers over Gadanki (13.5° N, 79.2° E)

P. Vishnu Prasanth, S. Sridharan, Y. Bhavani Kumar, and D. Narayana Rao

Abstract. We studied the characteristics of sporadic sodium layers (SSLs) observed with the sodium (Na) resonance scattering lidar at Gadanki (13.5° N, 79.2° E). The SSLs were observed on a total of 63 occasions during 464 h of Na lidar observations from January 2005 to February 2006. The observations showed that one SSL event occurred, on average, every 7 h. The most prominent sporadic layer, which formed on 12 February 2005, exhibited a peak density of 60 722 Na atoms/cm³ around 92 km and it was nearly twice the peak density reported from elsewhere using ground-based observations. In general, the SSLs exhibited the following characteristics: (1) they developed at heights between 88 and 98 km with an average height around 94 km; (2) maximum density occurred during the early morning hours between 02:00 and 05:00 IST; (3) the ratio of the maximum peak Na density to the average density was normally around 3 to 5 and it exceeded even 10 in some cases; (4) the events lasted from a few minutes to several hours. The formation period of the SSLs was longer compared to the decay period of the SSLs. Most of the SSL events showed downward motions.