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All Journal Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Jurnal Fisika Unand Jurnal Ilmu Fisika
Shimomai, Toyoshi
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Astronomy Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Materials Science & Nanotechnology Physics

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Differences in Mechanisms of Orographic Rainfall over West Sumatra (Case Study: 10 April and 23 April 2004) Harjupa, Wendi; Shimomai, Toyoshi; Hashiguchi, Hiroyuki; Fujiyoshi, Yasushi; Kawashima, Masayuki
Jurnal Ilmu Fisika Vol 13, No 1 (2021): Published in March 2021
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jif.13.1.8-17.2021

Abstract

Two different mechanisms of orographic rainfall enhancement  in West Sumatra were investigated utilizing observed data during the Coupling Processes in the Equatorial Atmosphere (CPEA)-I campaign. The variation of the atmospheric conditions during the campaign was shown by rainfall, surface wind, humidity, and stability index. An X-band Doppler radar captured the atmospheric conditions related to the enhancement of orographic rainfall mechanisms. The dry and less stable atmospheric conditions resulted in the convective type of rainfall. In contrast, the humid and stable atmospheric conditions brought the large-scale rainfall in the mountainous region where the events took place coincided with the inactive and active MJO phases..
Comparison of Bright Band Radar from GPM and MRR Observation in West Sumatera Ramadhan, Ravidho; Marzuki, Marzuki; Vonnisa, Mutya; Harmadi, Harmadi; Hashiguchi, Hiroyuki; Shimomai, Toyoshi
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) 2021: Articles in Press
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v11n1.p%p

Abstract

AbstractThe Bright band (BB) measurement from NS scan on Global Precipitation Measurement (GPM) had been compared with Micro Rain Radar (MRR) which is installed in Kototabang, West Sumatera (0.23o S; 100.32oE; 865 m above sea level). The GPM data were collected from December 2014 to June 2018 and compared with MRR observation from January 2012 to August 2016. The BB values from these instruments were also compared with the values recommended by the International Telecommunication Union Recommendation (ITU-R) P.839. The BB from GPM and MRR shown slightly diurnal and seasonal variations. BB observations from GPM and MRR show good agreement with slightly difference in diurnal and seasonal variations. BB observations are more similar when the intensity of solar radiation is lower, ie at night (18.00-24.00 LT) until dawn (00.00-06.00 LT). Furthermore, MRR determined a slight bimodal pattern in the seasonal variation while GPM did not, it cause variation in observation of both instrument quite significant in seasonal variation. The largest different from the seasonal variation was observed in the summer season (Juni-August(JJA)). Moreover the measurement of the mean BB is still below the Freezing Height Level (FHL) value from ITU-R model, the measurement of both instruments obtained a high number than FHL considerably (>36 %). It showed the constant value for FHL in West Sumatera that would cause the attenuation estimation of microwaves to be less accurate.
Struktur Vertikal Distribusi Butiran Hujan di Kototabang Berdasarkan Pengamatan Micro Rain Radar (MRR) Rahayu, Indah; Marzuki, Marzuki; Hashiguchi, Hiroyuki; Shimomai, Toyoshi
Jurnal Fisika Unand Vol 5 No 4 (2016)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.5.4.287-296.2016

Abstract

Distribusi ukuran butiran hujan atau raindrop size distribution (RDSD) arah vertikal dari ketinggian 0,15 km hingga 4,65 km di Kototabang, Sumatera Barat, telah diteliti melalui pengamatan Micro Rain Radar (MRR) selama Januari-Desember 2012. Intensitas curah hujan (rainfall rate) dari Optical Rain Gauge (ORG) dan RDSD dari Parsivel digunakan untuk menguji kinerja MRR. Pengujian memperlihatkan bahwa MRR berfungsi dengan baik dimana intensitas curah hujan dari ORG berkorelasi dengan baik dengan MRR (r = 0,98) dan RDSD dari MRR secara umum juga memperlihatkan pola dan nilai yang sama dengan yang didapatkan Parsivel.  Selanjutnya, RDSD dari MRR dimodelkan dengan distribusi gamma dan parameternya didapatkan menggunakan metode momen.  Terlihat bahwa pertumbuhan RDSD di Kototabang dari ketinggian 4,65 km hingga 0,15 km sangat kuat yang kemungkinan disebabkan oleh proses tumbukan-penggabungan.  Hal ini ditandai dengan peningkatan konsentrasi butiran berukuran besar dengan penurunan ketinggian.  Peningkatan konsentrasi butiran hujan berukuran besar terhadap penurunan ketinggian berpengaruh kepada parameter-parameter hujan seperti radar reflectivity (Z) dan rainfall rate (R) yang menyebabkan peningkatan koefisien A (Z= ARb) terhadap penurunan ketinggian.  Dengan demikian, penggunaan persamaan Z-R yang konstan untuk setiap ketinggian bagi radar meteorologi di kawasan tropis khususnya Sumatera Barat tidak  tepat.Kata kunci: raindrop size distribution, MRR, Kototabang, distribusi gamma.
Perbandingan Karakteristik Distribusi Butiran Hujan yang Berasal dari Awan Laut dan Awan Darat di Kototabang Fadillah, Nur; Marzuki, Marzuki; Harjupa, Wendi; Shimomai, Toyoshi; Hashiguchi, Hiroyuki
Jurnal Fisika Unand Vol 5 No 3 (2016)
Publisher : Universitas Andalas

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.25077/jfu.5.3.273-282.2016

Abstract

Karakteristik distribusi ukuran butiran hujan atau raindrop size distribution (RDSD) dari hujan yang berasal dari awan laut dan awan darat di Kototabang, Sumatera Barat, telah dibandingkan. Asal hujan diamati menggunakan X-band Doppler radar (XDR) selama proyek Coupling Processes in the Equatorial Atmosphere (CPEA)-I (10 April 2004 - 9 Mei 2004). Data RDSD berasal dari pengamatan two-dimensional video disdrometer (2DVD). RDSD dimodelkan dengan distribusi gamma dan parameternya didapatkan menggunakan metode momen. Dari penelitian ini terlihat bahwa intensitas curah hujan yang tinggi lebih banyak pada hujan dari awan darat dibandingkan dengan yang dari awan laut. Selain itu, butiran hujan yang berukuran besar pada awan darat lebih banyak daripada awan laut. Banyaknya butiran hujan dengan ukuran yang besar ini berdampak kepada nilai radar reflectivity (Z) pada awan darat yang lebih besar dibandingkan dengan awan laut untuk intensitas curah hujan yang sama. Hal ini mengakibatkan persamaan Z-R antara awan darat dan awan laut berbeda dimana nilai koefisien A dari persamaan Z-R untuk awan darat lebih besar daripada awan laut. Dengan demikian, perbedaan karaktersitik RDSD antara awan darat dan laut sebaiknya dipertimbangkan dalam pengembangan radar meteorologi di kawasan tropis. Penggunaan Z-R tunggal (Z = 200R1,6) untuk mengkoversi data radar cuaca di Sumatera terutama Sumatera Barat tidak akan akurat terutama untuk hujan dari awan laut.Kata kunci: distribusi butiran hujan (RDSD), awan darat, awan laut, Kototabang
Comparison of Bright Band Radar from GPM and MRR Observation in West Sumatera Ramadhan, Ravidho; Marzuki, Marzuki; Vonnisa, Mutya; Harmadi, Harmadi; Hashiguchi, Hiroyuki; Shimomai, Toyoshi
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Vol. 11 No. 1 (2021)
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v11n1.p50-62

Abstract

The Bright band (BB) observation can be used as an indication of the melting layer height. Measurement of BB from Normal Scan (NS) on Global Precipitation Measurement (GPM) had been compared with Micro Rain Radar (MRR), which is installed in Kototabang, West Sumatera (0.23° S; 100.32°E; 865 m above sea level). The GPM data were collected from December 2014 to June 2018 and compared with MRR observation from January 2012 to August 2016. The BB values from these instruments were compared with those recommended by the International Telecommunication Union Recommendation (ITU-R) P.839. The BB from GPM and MRR showed slightly diurnal and seasonal variations. BB observations from GPM and MRR show good agreement with slight diurnal and seasonal variations differences. BB observations are more similar when the intensity of solar radiation is lower, i.e., at night (18.00-24.00 LT) until early morning (00.00-06.00 LT). Furthermore, MRR showed a slight bimodal pattern in the seasonal variation, while GPM did not. Thus, the seasonal variation in the observation of both instruments is different. The most significant difference from the seasonal variation was observed in the summer season (June-August (JJA)). The mean BB of the two instruments is lower than the Freezing Height Level (FHL) value calculated from the ITU-R model. However, many BB from the two instruments (>36 %) have a BB altitude higher than FHL. Thus, the constant assumption of FHL in West Sumatera for the rain attenuation estimation of microwaves may not be appropriate.
Co-Authors Fujiyoshi, Yasushi Harmadi Harmadi Hiroyuki Hashiguchi, Hiroyuki Kawashima, Masayuki Marzuki Marzuki Marzuki Marzuki Mutya Vonnisa Nur Fadillah, Nur Rahayu, Indah Ramadhan, Ravidho Wendi Harjupa