Retrieval of Vertical Structure of Raindrop Size Distribution from Equatorial Atmosphere Radar and Boundary Layer Radar

Mutya Vonnisa, Toyoshi Shimomai, Hiroyuki Hashiguchi, Marzuki Marzuki


This work develops an algorithm to retrieve the vertical structure of the raindrop size distribution (DSD) of rain from simultaneous observations of 47 MHz Equatorial Atmosphere Radar (EAR) and 1.3 GHz Boundary Layer Radar (BLR) at Koto Tabang, West Sumatra, Indonesia (0.20°S, 100.32°E, 865 m above sea level). EAR is sensitive to the detection of turbulence, and BLR is susceptible to identifying precipitation echo. The EAR Doppler spectrum broadening effects due to turbulence and finite radar beam width were reduced using the convolution process. The Gaussian function was used to model the turbulence Doppler spectrum. A non-linear least-squares fitting method was applied to retrieve DSD parameters. Subsequently, the equations to estimate DSD using this dual-frequency algorithm assume the gamma DSD model to retrieve the distribution from the Doppler spectrum of precipitation echo. The precipitation events on April 23, 2004 on the Coupling Processes in the Equatorial Atmosphere (CPEA-I) project have been analyzed. Results show that the precipitation spectrum obtained using the dual-frequency method is higher, more precise, and well-fitted than the single-frequency method, meaning the dual-frequency method has great potential to be used in observing the microphysical process and remote sensing application analysis of DSD in Indonesia, particularly at Koto Tabang. The analyses show various microphysical processes that occur in the rain, such as coalescence, evaporation, break-up, and condensation. Furthermore, for the purpose of easier remote sensing application analysis of profile DSD characteristics, we use a DSD ΔΖMP parameter. ΔΖMP is a rain rate insensitive DSD parameter representing mean drop size. The trend of ΔZMP is not totally uniform with regards to rain rate and reflectivity factors, with ΔZMP higher in the first half of the event and becoming lower toward the end. This suggests that we have to use different Z-R relations within the event.


Doi: 10.28991/ESJ-2022-06-03-02

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Raindrop Size Distribution (DSD); Equatorial Atmosphere Radar (EAR); Boundary Layer Radar (BLR); Dual-Frequency; Koto Tabang.


Tokay, A., & Short, D. A. (1996). Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds. Journal of Applied Meteorology, 35(3), 355–371. doi:10.1175/1520-0450(1996)035<0355:EFTRSO>2.0.CO;2.

Pruppacher, H. R., Klett, J. D., & Wang, P. K. (1998). Microphysics of Clouds and Precipitation. Aerosol Science and Technology, 28(4), 381–382. doi:10.1080/02786829808965531.

Marzuki, M., Kozu, T., Shimomai, T., Randeu, W. L., Hashiguchi, H., & Shibagaki, Y. (2009). Diurnal variation of rain attenuation obtained from measurement of raindrop size distribution in equatorial Indonesia. IEEE Transactions on Antennas and Propagation, 57(4 PART 2), 1191–1196. doi:10.1109/TAP.2009.2015812.

Ulaganathen, K., Rahman, T. A., Rahim, S. K. A., & Islam, R. M. (2013). Review of rain attenuation studies in tropical and equatorial regions in Malaysia: An overview. IEEE Antennas and Propagation Magazine, 55(1), 103–113. doi:10.1109/MAP.2013.6474490.

Caracciolo, C., Napoli, M., Porcù, F., Prodi, F., Dietrich, S., Zanchi, C., & Orlandini, S. (2012). Raindrop Size Distribution and Soil Erosion. Journal of Irrigation and Drainage Engineering, 138(5), 461–469. doi:10.1061/(asce)ir.1943-4774.0000412.

Coppens, D., & Haddad, Z. S. (2000). Effects of raindrop size distribution variations on microwave brightness temperature calculation. Journal of Geophysical Research Atmospheres, 105(D19), 24483–24489. doi:10.1029/2000JD900226.

Kozu, T., & Nakamura, K. (1991). Rainfall parameter estimation from dual-radar measurements combining reflectivity profile and path-integrated attenuation. Journal of Atmospheric and Oceanic Technology, 8(2), 259-270. doi: 10.1175/1520-0426(1991)008<0259:RPEFDR>2.0.CO;2.

Rosenfeld, D., & Ulbrich, C. W. (2003). Cloud Microphysical Properties, Processes, and Rainfall Estimation Opportunities. Meteorological Monographs, 30(52), 237–237. doi:10.1175/0065-9401(2003)030<0237:cmppar>;2.

Thurai, M., Bringi, V., Gatlin, P. N., Petersen, W. A., & Wingo, M. T. (2019). Measurements and modeling of the full rain drop size distribution. Atmosphere, 10(1). doi:10.3390/atmos10010039.

Suzuki, K., Shimizu, K., Ohigashi, T., Tsuboki, K., Oishi, S., Kawamura, S., Nakagawa, K., Yamaguchi, K., & Nakakita, E. (2012). Development of a new videosonde observation system for In-situ precipitation particle measurements. Scientific Online Letters on the Atmosphere, 8(1), 1–4. doi:10.2151/sola.2012-001.

Sheppard, B. E., & Joe, P. I. (2008). Performance of the precipitation occurrence sensor system as a precipitation gauge. Journal of Atmospheric and Oceanic Technology, 25(2), 196–212. doi:10.1175/2007JTECHA957.1.

Ramadhan, R., Marzuki, & Harmadi. (2021). Vertical characteristics of raindrops size distribution over sumatra region from global precipitation measurement observation. Emerging Science Journal, 5(3), 257–268. doi:10.28991/esj-2021-01274.

Sato, T., Teraoka, T., Kimura, I., Hashiguchi, H., & Fukao, S. (n.d.). Simultaneous observation of raindrop size distribution by VHF and L-band Doppler radars. Proceedings of IEEE Antennas and Propagation Society International Symposium and URSI National Radio Science Meeting. Seattle, United State doi:10.1109/aps.1994.408143

Schafer, R., Avery, S., May, P., Rajopadhyaya, D., & Williams, C. (2002). Estimation of rainfall drop size distributions from dual-frequency wind profiler spectra using deconvolution and a nonlinear least squares fitting technique. Journal of Atmospheric and Oceanic Technology, 19(6), 864–874. doi:10.1175/1520-0426(2002)019<0864:EORDSD>2.0.CO;2.

Iwasaki, S., Okamoto, H., Hanado, H., Reddy, K. K., Horie, H., Kuroiwa, H., & Kumagai, H. (2005). Retrieval of raindrop and cloud particle size distributions with 14 GHz and 95 GHz radars. Journal of the Meteorological Society of Japan, 83(5), 771–782. doi:10.2151/jmsj.83.771.

Marzuki, M., Hashiguchi, H., Yamamoto, M. K., Mori, S., & Yamanaka, M. D. (2013). Regional variability of raindrop size distribution over Indonesia. Annales Geophysicae, 31(11), 1941–1948. doi:10.5194/angeo-31-1941-2013.

Murata, F., Yamanaka, M. D., Fujiwara, M., Ogino, S. Y., Hashiguchi, H., Fukao, S., Kudsy, M., Sribimawati, T., Harijono, S. W. B., & Kelana, E. (2002). Relationship between wind and precipitation observed with a UHF radar, GPS rawinsondes and surface meteorological instruments at Kototabang, West Sumatera during September-October 1998. Journal of the Meteorological Society of Japan, 80(3), 347–360. doi:10.2151/jmsj.80.347.

Kozu, T., Shimomai, T., Akramin, Z., Marzuki, Shibagaki, Y., & Hashiguchi, H. (2005). Intraseasonal variation of raindrop size distribution at Koto Tabang, West Sumatra, Indonesia. Geophysical Research Letters, 32(7), 1–4. doi:10.1029/2004GL022340.

Renggono, F., Yamamoto, M. K., Hashiguchi, H., Fukao, S., Shimomai, T., Kawashima, M., & Kudsy, M. (2006). Raindrop size distribution observed with the Equatorial Atmosphere Radar (EAR) during the Coupling Processes in the Equatorial Atmosphere (CPEA-I) observation campaign. Radio Science, 41(5). doi:10.1029/2005RS003333.

Marzuki, F., Kozu, T., Shimomai, T., Hashiguchi, H., Randeu, W. L., & Vonnisa, M. (2010). Raindrop size distributions of convective rain over equatorial Indonesia during the first CPEA campaign. Atmospheric Research, 96(4), 645–655. doi:10.1016/j.atmosres.2010.03.002.

Fukao, S., Hashiguchi, H., Yamamoto, M., Tsuda, T., Nakamura, T., Yamamoto, M. K., Sato, T., Hagio, M., & Yabugaki, Y. (2003). Equatorial atmosphere radar (EAR): System description and first results. Radio Science, 38(3). doi:10.1029/2002RS002767.

Rajopadhyaya, D. K., May, P. T., & Vincent, R. A. (1993). A general approach to the retrieval of raindrop size distributions from wind profiler Doppler spectra: modeling results. Journal of Atmospheric & Oceanic Technology, 10(5), 710–717. doi:10.1175/1520-0426(1993)010<0710:AGATTR>2.0.CO;2.

Renggono, F., Hashiguchi, H., Fukao, S., Yamanaka, M. D., Ogino, S. Y., Okamoto, N., Murata, F., Sitorus, B. P., Kudsy, M., Kartasasmita, M., & Ibrahim, G. (2001). Precipitating clouds observed by 1.3-GHz boundary layer radars in equatorial Indonesia. Annales Geophysicae, 19(8), 889–897. doi:10.5194/angeo-19-889-2001.

Hashiguchi, H., Fukao, S., Tsuda, T., Yamanaka, M. D., Tobing, D. L., Sribimawati, T., Harijono, S. W. B., & Wiryosumarto, H. (1995). Observations of the planetary boundary layer over equatorial Indonesia with an L band clear‐air Doppler radar: Initial results. Radio Science, 30(4), 1043–1054. doi:10.1029/95RS00653.

Hashiguchi, H., Fukao, S., Tsuda, T., Yamanaka, M. D., Harijono, S. W. B., & Wiryosumarto, H. (1996). An overview of the planetary boundary layer observations over equatorial Indonesia with an L-band clear-air doppler radar. Contributions to Atmospheric Physics, 69(1), 13–25. doi: 10.1029/95RS00653.

Testud, J., Oury, S., Black, R. A., Amayenc, P., & Dou, X. (2001). The concept of “normalized” distribution to describe raindrop spectra: A tool for cloud physics and cloud remote sensing. Journal of Applied Meteorology, 40(6), 1118–1140. doi:10.1175/1520-0450(2001)040<1118:TCONDT>2.0.CO;2.

Kozu, T., Reddy, K. K., Shimomai, T., Hashiguchi, H., Ohno, Y., & Minami, S. (2003). Estimation of raindrop size distribution profile with atmosphere radars at south India and Sumatera. Japanese URSI-F meeting, 5 - 6 September, 2019, Tokyo, Japan.

Ulbrich, C. W., & Atlas, D. (1977). A method for measuring precipitation parameters using radar reflectivity and optical extinction. Annales Des Télécommunications, 32(11–12), 415–421. doi:10.1007/BF03003488.

Krishna Reddy, K., Kozu, T., Ohno, Y., Jain, A. R., & Narayana Rao, D. (2005). Estimation of vertical profiles of raindrop size distribution from the VHF wind profiler radar Doppler spectra. Indian Journal of Radio and Space Physics, 34(5), 319–327.

Rajopadhyaya, D. K., May, P. T., Cifelli, R. C., Avery, S. K., Willams, C. R., Ecklund, W. L., & Gage, K. S. (1998). The effect of vertical air motions on rain rates and median volume diameter determined from combined UHF and VHF wind profiler measurements and comparisons with rain gauge measurements. Journal of Atmospheric and Oceanic Technology, 15(6), 1306–1319. doi:10.1175/1520-0426(1998)015<1306:TEOVAM>2.0.CO;2.

Williams, C. R. (2002). Simultaneous ambient air motion and raindrop size distributions retrieved from UHF vertical incident profiler observations. Radio Science, 37(2), 8-1-8–16. doi:10.1029/2000rs002603.

Lucas, C., MacKinnon, A. D., Vincent, R. A., & May, P. T. (2004). Raindrop size distribution retrievals from a VHF boundary layer profiler. Journal of Atmospheric and Oceanic Technology, 21(1), 45–60. doi:10.1175/1520-0426(2004)021<0045:RSDRFA>2.0.CO;2.

Kobayashi, K., Shige, S., & Yamamoto, M. K. (2018). Vertical gradient of stratiform radar reflectivity below the bright band from the Tropics to the extratropical latitudes seen by GPM. Quarterly Journal of the Royal Meteorological Society, 144, 165–175. doi:10.1002/qj.3271.

Meneghini, R., & Kozu, T. (1990). Spaceborne weather radar. Artech House Publisher, Norwood, Massachusetts, United States.

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DOI: 10.28991/ESJ-2022-06-03-02


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