Deteksi pengaruh gelombang Kelvin pada fluktuasi uap air di tropopause menggunakan model inversi

• Main Authors: Dita Fatria Andarini, Noersomadi Noersomadi
• Format: Article
• Language: Indonesian
• Published: Universitas Gadjah Mada 2020-09-01
• Series: Majalah Geografi Indonesia
• Subjects: uap air; gelombang kelvin; tropopause; model inversi
• Online Access: https://jurnal.ugm.ac.id/mgi/article/view/54759

Analisis pengaruh gelombang ekuatorial Kelvin terhadap fluktuasi uap air (H2O) di lapisan tropopause (paras tekanan udara 100 hPa), dilakukan dengan  memanfaatkan data Microwave Limb Sounder (MLS) Aura versi 4.2 dan angin zonal NCEP DOE Reanalysis II sepanjang tahun 2017. Model inversi gelombang melalui pendekatan Newtonian diterapkan untuk mencari parameter amplitudo (A) dan fasa (φ) gelombang dominan pada variasi anomali H2O (H2O*). Hasil penyelarasan model inversi menunjukkan perambatan H2O* positif ke arah timur bersesuaian dengan angin zonal (U) positif (angin baratan) yang identik dengan pergerakan gelombang Kelvin. Perambatan ini didominasi oleh bilangan gelombang k1 dengan A1 dan φ1 berturut–turut sebesar 0,44 dan 21,1°.  Penulis menemukan bahwa variasi uap air dipengaruhi oleh perubahan angin baratan menjadi angin timuran dan konvergensi sebesar 0,15 × 10–5 s–1. Analisis komposit diagram relatif terhadap nilai maksimum H2O* menunjukkan adanya pengaruh gelombang ekuatorial Kelvin terhadap distribusi uap air di tropopause. Penelitian terkait pengembangan model kopel troposfer dan stratosfer perlu mempertimbangkan proses dinamika gelombang Kelvin dan proses radiatif dari konsentrasi uap air di tropopause.   Analysis on the influence of equatorial Kelvin wave on the fluctuations in water vapor (H2O) at tropopause (100 hPa air pressure level) has been done utilizing Microwave Limb Sounder (MLS) Aura version 4.2 and zonal wind (U) from NCEP DOE Reanalysis II data throughout the year of 2017. The inverse wave model using Newtonian approximation has been applied to determine the dominant of both wave amplitude (A) and phase (φ) parameters on the H2O anomaly (H2O*). The fitting of inverse modeling result showed an eastward propagation of positive H2O* associated with positive U (westerly wind) which is identical as Kelvin wave movement. The propagation is dominated by wavenumber k1 where A1 and φ1 is 0.44 and is 21.1°, respectively.  The authors found that water vapor variations were influenced by the reversal of zonal wind from easterly to easterly and the convergence as large as 0,15 × 10–5 s–1. The composite analysis relative to the maximum value H2O* showed the influence of equatorial Kelvin wave in the water vapor distribution at tropopause. The research on the development of the troposphere –stratosphere coupling model may need to consider the dynamical process of the equatorial Kelvin wave and radiative process of water vapor concentration in the tropopause.