Abstract
Abstract. A rare occurrence of stratospheric cirrus at 18.6 km height persisting for about 5 days during 3–7 March 2014 is inferred from the ground-based Mie lidar observations over Gadanki (13.5° N, 79.2° E) and spaceborne observations. Due to the vertical transport by large updrafts on 3 March in the troposphere, triggered by a potential vorticity intrusion, the water vapour mixing ratio shows an increase around the height of 18.6 km. Relative humidity with respect to ice is ~ 150%, indicating that the cirrus cloud may be formed though homogeneous nucleation of sulfuric acid. The cirrus cloud persists due to the cold anomaly associated with the presence of a 4-day wave.
Highlights
Cirrus clouds are ubiquitous over the tropics and they significantly influence the radiation budget by reflecting incoming sunlight and regulating outgoing heat radiation from Earth’s surface (Liou, 1986; Boehm et al, 1999; Ramanathan and Collins, 1991; Prabhakara et al, 1993)
As the cold point tropopause heights obtained from the radiosonde temperature observations are found to be 16.8, 17.1, 16.6 km on the days 5–7 March 2014, respectively, with temperatures around 190 K (Fig. 1d), the cirrus clouds appear just above the tropopause in the lower stratosphere
Kulkarni et al (2008) studied the frequency of occurrence of cirrus over Gadanki using Mie lidar observations for the years 2001–2005 and they found that 22 % of cirrus top occurs in the 16–17 km height region, 15 % of cirrus top occurs at 10–12 km, and only less than 5 % of cirrus top www.ann-geophys.net/33/599/2015/
Summary
Cirrus clouds are ubiquitous over the tropics and they significantly influence the radiation budget by reflecting incoming sunlight and regulating outgoing heat radiation from Earth’s surface (Liou, 1986; Boehm et al, 1999; Ramanathan and Collins, 1991; Prabhakara et al, 1993). They play a role in the dehydration in the tropical tropopause layer and on stratospheric humidity (Gettleman et al, 2002; Jensen et al, 1996a, 2001).
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