Statistical morphology of cloud occurrences and cloud attenuation over Hyderabad, India

Abstract

Attenuation due to clouds in millimeter wave and microwave frequency bands lead to degradation in the performance of radio communication, especially for low noise systems. Frequent presence of cloud causes some amount of link degradation for significant percentage of time over the tropical Indian subcontinent. The cloud morphology particularly in relation to radio wave propagation over different geographical region of India is very essential and important. In view of this, systematic studies on cloud occurrence morphology over different geographical locations in India have been undertaken. Based on low level cloud coverage observations, frequency of cloud occurrences over Hyderabad (17.27°N,

78.28°E), situated in Indian tropical southern region in different months during daytime and nighttime has been deduced and presented in this paper. The low-level cloud over Hyderabad has been found to occur for many days and nights and particularly in the months of June-September. The low level cloud occurrences are minimum in winter months. The specific attenuation of radiowave due to clouds at various frequencies -10, 20, 30, 40, 50, 75 and 100 GHz for summer and monsoon seasons has also been deduced. The specific attenuation of radio wave due to cloud at 30 GHz for liquid water content ~1 g/m³ is found to be 0.88 dB/km, while at 75 GHz the specific attenuation is ~5.55 dB/km.