Lidar observations of cirrus cloud near the tropical tropopause: general features

Semitransparent cirrus clouds in the tropical tropopause layer during two contrasting seasons

“…In general, the frequency of occurrence of STC within the TTL (14-17 km) is found to be quite large compared to that in the region outside. Sunilkumar et al (2003) studied the general features of tropical cirrus from long-term lidar data at Gadanki and showed that the most favorable altitude for the occurrence of cirrus is around 14-16 km (the TTL region). They observed that the frequency of occurrence of cirrus in the altitude region 14-17 km (TTL cirrus) is greater than 70% while that below 14 km (non-TTL cirrus) is less than 30%.…”

Rayleigh lidar observations of quasi‐sinusoidal waves in the tropical middle atmosphere

“…Statistical error due to signal variance, in general, is small (∼1 K) at lower altitudes (30–50 km), which increases with increase in altitude (∼2.5 K at 65 km). Above ∼25 km, the contribution to the lidar backscattered signal from aerosol scattering is insignificant [ Sunil Kumar et al , 2003]. Though the temperatures are derived up to 80 km, to minimize the uncertainty due to the various errors discussed above, data in altitude region of the 27 to 60 km alone is used in the present study.…”

Latitudinal dependence of the seasonal variation of particulate extinction in the UTLS over the Indian longitude sector during volcanically quiescent period based on lidar and SAGE-II observations

“…The signal-to-noise ratio of the raw data was always42 for all altitudes below 45 km all through the observation period. More details regarding the lidar system and retrieval of backscatter coefficient are detailed in earlier publications (Sunilkumar et al, 2003(Sunilkumar et al, , 2008.…”

“…(for cross-polarized) and volume depolarization ratio (VDR), d¼b? (h)/b:(h) (Sunilkumar et al, 2003). Incorporating the lidar ratio (extinction to backscatter ratio for particulates), S 1 , Eq.…”

“…Properties of suspended particulates in the UTLS region at a tropical station Gadanki (13.51N,79.21E) were studied in detail by quite a few investigators (Sunilkumar et al, 2003;Kulkarni et al, 2008) using the ground based lidar system. The recent study by Thampi et al (2009) on the characteristics of particulate matter in the UTLS region during the volcanic quiescent period of 1998-2003 revealed a pronounced summer-winter contrast of the particulate backscatter in the LS region with relatively high values during winter and low values during summer.…”