Climatology Of Thin Cirrus Clouds at Gadanki (13.5°N, 79.2°E) Using Ground Based Lidar And Satellite Based Measurements
Other literature type
Motty, G. S.
Jayeshlal, G. S.
(issn: 2194-9034, eissn: 2194-9034)
High altitude cirrus clouds play a significant role in the radiative balance of Earth atmosphere system. Information on cirrus
occurrences and their optical properties is essential for climate modeling studies. The influence of high altitude thin cirrus clouds
on the climate is important due to their optical and thermodynamic properties. In order to quantify their effect on atmosphere, the
vertical structure and optical properties of these thin cirrus clouds are to be characterized. The Lidar technique has become a
unique tool for detecting and characterizing cirrus clouds for their optical properties. Ground based LIDAR system offers an
excellent way to obtain characteristic values on the cirrus formations, although the microphysical and optical properties of thin
cirrus clouds can also obtained on global scale by the observations from Earth-orbiting Satellites .The ground-based lidar
observations could provide more intensive measurements on continuous basis, compared to satellite observations. Utilising
observations from both, the statistical characteristics, physical and optical properties of thin cirrus clouds can be retrieved more
precisely. The present study is based on the ground based lidar measurements using the pulsed monostatic LIDAR system at the
National Atmospheric Research Laboratory [NARL], Gadanki (13.5° N, 79.2° E), Andhra Pradesh, India. The data obtained in the
altitude range of 8−20 km are used for this study. Cirrus observations made using CALIPSO and MODIS satellites are compared
with the ground based lidar data for systematic statistical study of cirrus climatology. Optically thin cirrus clouds (τ < 0.3) observed
during 2009 are selected and their microphysical and geometrical properties are studied. The microphysical properties such as
optical depth, lidar ratio and depolarisation ratio for cirrus clouds were obtained. It is observed that the variability in optical depth
depends on the composition and thickness of the clouds. The relationships between various quantities were also processed. The
study shows that the thin cirrus generally was present in higher altitudes and the optical properties show correlation with the
height and the temperature.