Rain attenuation prediction during rain events in different climatic regions Dalia Das a,n , Animesh Maitra b a Department of Electronics and Telecommunication Engineering, Meghnad Saha Institute of Technology, Techno Complex, Madurdaha, Kolkata 700 150, India b S K Mitra Centre for Research in Space Environment, Institute of Radio Physics and Electronics, University of Calcutta, Kolkata 700 009, India article info Article history: Received 30 July 2014 Received in revised form 4 March 2015 Accepted 5 March 2015 Available online 7 March 2015 Keywords: Rain attenuation Time series prediction Propagation channel Earth-space path abstract A rain attenuation prediction method has been applied to different climatic regions to test the validity of the model. The significant difference in rain rate and attenuation statistics for the tropical and temperate region needs to be considered in developing channel model to predict time series of rain attenuation for earth space communication links. Model parameters obtained for a tropical location has been success- fully applied to predict time series of rain attenuation at other tropical locations. Separate model para- meters are derived from the experimental data obtained at a temperate location and these are used to predict rain attenuation during rain events for other temperate locations showing the effectiveness of the technique. & 2015 Elsevier Ltd. All rights reserved. 1. Introduction Due to the congestion at the lower frequency bands, the sa- tellite communication systems are now operating at the higher frequency Ku or Ka bands (Ku or Ka). However in these bands, mainly above 10 GHz, rain events cause severe attenuation to the propagating signal along earth space communication link. If time series prediction of rain attenuation during rain events is possible, fade countermeasure techniques such as adaptive control of signal power, coding and data rate can be effectively implemented to mitigate this attenuation effect. Channel models in the form of time series generators of rain rate and attenuation have been de- veloped previously (Alassur et al., 2004; Fontan et al., 2007; Heder and Bito, 2008; Carrie et al., 2011; Lemorton et al., 2007). So far, they have not been used to predict rain attenuation or rain rate during rain events at different points of time. There exist various short term rain attenuation prediction methods (Castanet, 2001; Gremont, 1997; Van de Kamp, 2002; Montera et al., 2008; Bolea- Alamanac et al., 2003), all of which predict a single attenuation value a short time before the actual occurrence, but not the time series of attenuation values for the entire rain event. The above mentioned models are validated on long term basis and not on event by event basis. In the present study, a channel model has been developed to predict time series of rain attenuation during the entire rain event. This model is not only tested on long term basis but also event wise. In our earlier paper (Das and Maitra, 2012a, 2012b), the same method has been discussed for rain attenuation and rain rate prediction for experimental data obtained at Kolkata, a tropical location. However, the effectiveness of the methodology needs to be tested for any locations in the globe. In this paper, rain rate and attenuation statistics obtained at tropical and temperate regions are compared. From the measured data set, model parameters are developed separately for tropical and temperate regions which are being used to predict the time series of rain attenuation for both the regions. 2. Comparision between tropical and temperate region Data sets from different sites in tropical region as well as in temperate region are taken to check the validity of our model. The details of the measurement links are given in (Maitra et al., 2007; Chakravarty and Mitra, 2010; Adhikari et al., 2011; Riva, 2004; Propagation data and prediction methods required for the design of Earth-space telecommunication systems, 2009; Sánchez-Lago et al., 2007) and also in Table 1 in a short form. To get proper comparison of attenuation statistics, for Spino d’ Adda and Kolkata measurements are taken at the frequency 11.6 GHz and 11.172GHz respectively. But to test the validity of the model in temperate region, at Spino d’ adda, attenuation measurements are also taken at 18.7 GHz as the other station data are at frequencies very near Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jastp Journal of Atmospheric and Solar-Terrestrial Physics http://dx.doi.org/10.1016/j.jastp.2015.03.003 1364-6826/& 2015 Elsevier Ltd. All rights reserved. n Corresponding author. E-mail addresses: dalia_das311@yahoo.co.uk, animesh.maitra@gmail.com (D. Das). Journal of Atmospheric and Solar-Terrestrial Physics 128 (2015) 1–7