Abstract
Abstract. Cloud vertical structure, including top and base altitudes, thickness of cloud layers, and the vertical distribution of multilayer clouds, affects large-scale atmosphere circulation by altering gradients in the total diabatic heating and cooling and latent heat release. In this study, long-term (11 years) observations of high-vertical-resolution radiosondes are used to obtain the cloud vertical structure over a tropical station at Gadanki (13.5∘ N, 79.2∘ E), India. The detected cloud layers are verified with independent observations using cloud particle sensor (CPS) sonde launched from the same station. High-level clouds account for 69.05 %, 58.49 %, 55.5 %, and 58.6 % of all clouds during the pre-monsoon, monsoon, post-monsoon, and winter seasons, respectively. The average cloud base (cloud top) altitudes for low-level, middle-level, high-level, and deep convective clouds are 1.74 km (3.16 km), 3.59 km (5.55 km), 8.79 km (10.49 km), and 1.22 km (11.45 km), respectively. Single-layer, two-layer, and three-layer clouds account for 40.80 %, 30.71 %, and 19.68 % of all cloud configurations, respectively. Multilayer clouds occurred more frequently during the monsoon with 34.58 %. Maximum cloud top altitude and cloud thickness occurred during the monsoon season for single-layer clouds and the uppermost layer of multiple-layer cloud configurations. In multilayer cloud configurations, diurnal variations in the thickness of upper-layer clouds are larger than those of lower-layer clouds. Heating and cooling in the troposphere and lower stratosphere due to these cloud layers are also investigated and peak cooling (peak warming) is found below (above) the cold-point tropopause (CPT) altitude. The magnitude of cooling (warming) increases from single-layer to four- or more-layer cloud occurrence. Further, the vertical structure of clouds is also studied with respect to the arrival date of the Indian summer monsoon over Gadanki.
Highlights
Clouds are vital in driving the climate system as they play an important role in radiation budget, general circulation, and the hydrological cycle (Ramanathan et al, 1989; Rossow and Lacis, 1990; Wielicki et al, 1995; Li et al, 1995; Stephens, 2005; Yang et al, 2010; Huang, 2013)
Passive-sensor satellite data, such as from ISCCP and MODIS, have some limitations in using the analyses presented in this study
Cloud layers during April 2006– May 2017 are averaged to obtain the composite picture of cloud vertical structure (CVS)
Summary
Clouds are vital in driving the climate system as they play an important role in radiation budget, general circulation, and the hydrological cycle (Ramanathan et al, 1989; Rossow and Lacis, 1990; Wielicki et al, 1995; Li et al, 1995; Stephens, 2005; Yang et al, 2010; Huang, 2013) By interacting with both shortwave and longwave radiation, clouds play a crucial role in the radiative budget at the surface, within, and at the top of the atmosphere (Li et al, 2011; Ravi Kiran et al, 2015; George et al, 2018). The National Atmospheric Research Laboratory (NARL) at Gadanki is located about 120 km north-west of Chennai (Madras) on the east coast of the southern Indian peninsula. This station is surrounded by hills with a maximum altitude www.atmos-chem-phys.net/18/11709/2018/. About 66 % of total rainfall is convective in nature, while the remaining rain is widespread stratiform in character (Rao et al, 2008a)
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