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Abstract: Melting layer height, which is normally assumed to be the limits of rain region, is an important parameter to consider the performance of earth space communication link above 10GHz. In this paper, the variation of melting layer observed by a vertically looking Micro Rain Radar (MRR) for 3years has been presented for two different climatic locations in Indian tropical region — Shillong (25°34′ N, 91°53′ E, 1050m) and Trivandrum (8°29′ N, 76°57′ E, 4m). The analyses show that the variation is quite significant for different months in Shillong but not for Trivandrum. The height of melting layer shows a strong correlation with ground temperature of these locations. The results agree well with the long term Tropical Rainfall Measuring Mission (TRMM) measurements of melting layer indicating suitability of using TRMM data for such study. A comparison of MRR with the nearest Radiosonde measurement indicates that MRR can have potential application in the study of zero degree isotherm height in rainy conditions. Results also clearly indicate that the assumption of constant rain height is not a valid one for all tropical locations. [Copyright &y& Elsevier]

• Signal attenuation due to orographic rain is analyzed at 20.2 GHz over hills. • Measured attenuation statistics are compared with ITU-R and Changsheng Model. • Ka band signal attenuation prediction model over hill region is Proposed and validated. Experimental measurement of satellite signal at 20.2 GHz using GSAT-14 satellite beacon has been carried out over the hilly tropical location Umiam, Shillong during 2017–2019. Collocated rainfall measurements have been done using a laser precipitation monitor for the same duration. The data have been analyzed to understand the signature of orographic rainfall on the Ka-band signal and to achieve the highest possible reliability of signal reception for a high rainfall tropical location. Complementary cumulative distribution of experimentally obtained rain attenuation is compared with that of conventional ITU-R model calculated rain attenuation and recently developed Chang Sheng model predicted rain attenuation values. The result shows severe overestimation of the actual measurement by both the ITU-R model and Chang Sheng model. The Chang Sheng model is further modified with the orographic adjustment factor for predicting orographic rain attenuation. The model was developed based on the data of 2017–18 and validated using the measured attenuation of the year 2019. The performance of the proposed model is evaluated in terms of RMSE and correlation coefficient. The value of the correlation coefficient has been found to be 0.988, and the RMSE value has been found to be around 3.0986, which indicates the acceptable performance of the proposed model. The proposed model is further optimized for operational elevation angle range, rain rate range, and frequency range. The proposed model will help in optimizing the power utilization in the Uplink Power Control technique for rain attenuation mitigation over high rainfall hilly regions. [ABSTRACT FROM AUTHOR]