|Published online: December 22, 2015||$US5.00|
In order to understand the dynamics of climate change and to adopt mitigation technique against it, it is necessary to know its impact on rainfall, one of the worst affected meteorological elements. Weather radars and satellites—proven to be the most effective instruments to estimate rainfall—need to explore high frequencies, namely the millimeter wave frequency range, because of its higher rate of data transmission, and also due to overcrowding at the lower frequency region. However, with an increase in frequency, the attenuation of the signal by rainfall increases. Above 10 GHz, the attenuation can be so severe that the link transmission may be significantly interrupted. Moreover, modern satellites adopting frequency reuse technique to increase the channel capacity suffer from unwanted cross polarization, which is attributed to the oblate shape of rain drops. Knowledge of co-polar attenuation is necessary to estimate cross polarization. Thus, the study of attenuation is of immense importance for an accurate estimation of rainfall. In this paper, the authors aim to study the attenuation at the Tropical Microwave Imager (TMI) channels, viz. 10.65, 19.35, 21.3, 37, and 85.5 GHz onboard the Tropical Rainfall Measuring Mission (TRMM) satellite over Salem, India by using the International Telecommunication Union (ITU-R) model. The TMI uses four of its channels in dual polarization mode, except the 21.3 GHz. The ITU-R model to estimate rainfall attenuation needs a one-minute rainfall interval. However, rainfall values are mostly available on hourly basis. This paper aims to seek a conversion formula between the two, if any, over Salem.
|Keywords:||Attenuation, Rainfall, TRMM, Tropics|
International Journal of Climate Change: Impacts and Responses, Volume 8, Issue 1, March 2016, pp.33-49. Article: Print (Spiral Bound). Published online: December 22, 2015 (Article: Electronic (PDF File; 1.341MB)).
Head, CRRP and Professor, Physics, Physics, Centre for Study on Rainfall and Radio wave Propagation, Sona College of Technology, Salem, Tamil Nadu, India
4th-year BE Electronics and Communication Engineering Student, Electronics and Communication Engineering, Sona College of Technology, Salem, Tamil Nadu, India
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