Characterization of Ka-band Radar Observations for Different Rain Types over Akure, Nigeria

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Joseph S. Ojo
Babatunde A. Alabi
Moses O. Ajewole


Radar is a unique tool that can measure precipitation parameters over a large aerial coverage. Its application spans over study of climate change and radiowave propagation. Inter-relation between the rain parameters can also be derived with the height of radar especially on vertical profiling or aloft ground level. Hence effect of precipitation parameters can be assessed along the satellite propagation path with the help of space-borne radar. Satellite communication links operating at frequencies above 10 GHz are usually affected by hydrometeors especially rainfall. These effects are expected to be quite severe in the tropical region like Akure due to the nature of precipitation which is mainly convective and stratiform rain type. Therefore, information on vertical rain structure is important for precise quantitative estimation of precipitation. Thus, the focus of this work is to characterize the vertical profile of rain structures using vertically-pointing Ka-band Micro Rain Radar (MRR) at Akure, Nigeria. This has been achieved by using 2-year (2013 and 2014) data of rain parameters namely: rain rate, reflectivity, liquid water content and fall velocity obtained from MRR to determine the bright band heights under different rain types and its implications on satellite and radio waves propagation in this region. Rain rate in this region has been categorized into four groups namely: 0.02- 0.2 mm/h, 0.2- 2 mm/h, 2-40 mm/h, and 40 - 200 mm/h. The very low rain rate group is related to the stratiform rain types whereas highest rain rate groups are for the convective rain type. Study shows that parameters that are much associated with rain attained peak value at different height depending on the period of the year. The vertical profile of Z shows peak around 3 to 4.2 km height. The peak region is associated with the bright band height and contribution to the melting layer. This study revealed that the occurrence of bright band heights varies with rain types. The overall results will be useful for determining rain height needed for the prediction of rain attenuation in this region.

Ka-band, radar, micro rain radar, precipitation, bright band height, stratiform, convective

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How to Cite
Ojo, J. S., Alabi, B. A., & Ajewole, M. O. (2020). Characterization of Ka-band Radar Observations for Different Rain Types over Akure, Nigeria. Physical Science International Journal, 24(3), 9-19.
Review Article


Ojo JS, Olurotimi EO. Tropical rainfall structure characterization over two stations in Southwestern Nigeria for radiowave propagation purposes. Journal of Emerging Trends in Engineering and Applied Sciences. 2014;5(2):116–122.

Chebil J, Rahman TA. Development of 1 min rain rate contour maps for microwave applications in Malaysia Peninsula. Electronics Letts. 1999;35:1712–1774.

Crane RK. Prediction of the effects of rain on satellite communication system. Proceedings of the IEEE. 1977;65:456–474.

Moupfounma F. Rainfall-rate distribution for radio system design. IEE Proceedings. 1997;134:527-537, Pt. H, No. 6.

Ojo JS, Ajewole MO, Sarkar SK. Rain rate and rain attenuation prediction for satellite communication in Ku and Ka bands over Nigeria. Prog Electromagn Res B (Hong Kong). 2008;207-223.

Marzuki, Hashiguchi H, Kozu T, Shimomai T, Shibagaki Y, Takahashi Y. Precipitation microstructure in different Madden-Julian Oscillation phases over Sumatra. Atmos. Res. 2016;168:121–138.

Ojo JS, Tomiwa AC, Ajewole MO. Characterization of vertical profile of rain microstructure using micro rain radar in a tropical part of Nigeria. Physical Science International Journal. 2018;18(1):1-12. Article no.PSIJ.36981.

Tridon F, Baelen JV, Pointin Y. Aliasing in micro rain radar data due to strong vertical winds. Geophys. Res. Lett. 2011;38: L02804.
DOI: 201110.1029/2010GL046018

Peters G, Fischer B, Clemens M. Rain attenuation of radar echoes considering finite-range resolution and using drop size distributions. J. Atmos. Ocean. Technol. 2010;27:829–842.

Peters G, Fischer B, Münster H, Clemens M, Wagner A. Profiles of raindrop size distributions as retrieved by micro rain radars. J. Appl. Meteorol. 2005;44:1930–1949.

Gerhard P, Fischer B, Münster H, Clemens M, Wagner A. Profiles of raindrop size distributions as retrieved by micro rain radars. Journal of Applied Meteorology. 2005;44:1930–1949.

Ajayi GO, Barbaliscia F. Prediction of attenuation due to rain: Characteristics of the 0°C isotherm in temperate and tropical climates. Int. J. of Sat. Comm. 1990;8:187-196.

Oluwadare EJ, Tomiwa AC, Ajewole MO. Investigation of Radiowave propagtion impairment at super high frequency due to Rain in Akure. American International Journal of Contemporary Research 2012;2(10):122. Rainfall estimates in stratiform rain. Weather Forecast. 23;1085–1101.

Das S, Shukla AK, Maitra A. Investigation of vertical profile of rain microstructure at Ahmedabad in Indian tropical region. Adv. Space Res. 2010;45(10):1235-1243.

Thurai M, Deguchi E, Okamoto K, Salonen E. Rain height variability in the tropics. IEE Proc. Microw. Antennas Propag. 2012;152(1):17-23.

Steiner M, Houze Jr. RA, Yuter SE. Climatological characterization of three-dimensional storm structure from operational radar and rain gauge data. J. Appl. Meteor. 1995;34:1978–2007.
DOI: 10.1175/1520-0450(1995)034,1978: CCOTDS.2.0.CO;2.

Awaka J, Iguchi T, Okamoto K. Early results on rain type classification by the tropical rainfall measuring mission (TRMM) precipitation radar. Proc. 8th URSI Commission F. Open Symp. Aveiro, Portugal. 1998;143-146.

Williams CR, Ecklund WL, Gage KS. Classification of precipitating clouds in the tropics using 915–MHz wind profilers. J. Atmos. Ocean. Tech. 1995;12:996–1012.