Estimates of water vapour absorption over Calcutta at 22.235 GHz

Abstract

The vertical attenuation rates (dB km Õ 1 ) due to the water vapour monomer model in the atmosphere at 22.235 GHz were estimated. The height distribution of meteorological parameters such as atmospheric pressure, temperature, water vapour pressure and water vapour densities along with attenuation rate were found to be best ® tted exponentially, except for the temperature distribution. Thus, the seasonal variation of estimated attenuation and the brightness temperatures were compared with the experimentally obtained radiometric observations at 22.235 GHz. Correlations between the estimated and observed values were studied. Then, by using the absorption data, water vapour scale height was determined. For this purpose, the inversion algorithm has been developed and results were in agreement with the estimated values. The water vapour scale height over Calcutta varied between 2.0 and 2.5 km.

Ground-based single-frequency microwave radiometric measurement of water vapour

“…This may help us to estimate the water vapour content and its corresponding attenuation in the rainiest month in Brazil (22 • South). One of the authors has made this type of study at Kolkata (22 • North) (Karmakar et al 1999). Although the latitudinal occupancy of both places is the same, the measurement of water over Brazil draws special attention because of entirely different environmental conditions, especially due to the Amazon basin.…”

“…So if we can measure the water Downloaded by [Universitätsbibliothek Bern] at 11:23 26 August 2014 vapour scale height from radiometric measurement it would then be convenient to get the vertical profile of water vapour. For this purpose, we take advantage of the algorithm developed by Karmakar et al (1999), applicable for single-frequency 22.234 GHz, wherein the water vapour scale height, H ρ , was found to be…”