IDENTIFIKASI GELOMBANG KELVIN DI LAPISAN TROPOPAUSE INDONESIA BAGIAN BARAT DENGAN MENGGUNAKAN DATA SOUNDING NOAA
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Abstract
Gelombang Kelvin, Tropopause, Angin zonal. Gelombang Kelvin yang sebelumnya teramati pada lapisan stratosfer bawah berada di wilayah India dan Pasifik barat. Posisi Indonesia yang berada diantara dua wilayah tersebut memungkinkan terjadinya gelombang Kelvin di wilayah Indonesia. Namun, karakter yang teramati belum tentu sama. Pada bulan JJAS, gelombang Kelvin yang teramati memiliki periode 10-20 harian sedangkan pada bulan DJFM memiliki periode 20 harian. Gelombang Kelvin tersebut merambat ke timur. Adanya aktivitas konvektif yang besar di wilayah Indonesia mampu mengganggu perambatan gelombang Kelvin. Awan-awan konvektif tersebut ditunjukkan dengan menggunakan data OLR. Pada periode JJAS, gangguan tersebut kuat pada bagian bumi utara sedangkan pada periode DJFM pada ekuator. Adanya gangguan tersebut dapat meningkatkan angin timuran sehingga meningkatkan amplitudo gelombang di bagian bumi utara pada JJAS dan bagian bumi selatan pada DJFM. Dari analisis pada lapisan 500-150 mb, terlihat adanya osilasi 20 harian (JJAS) dan 10-20 harian (DJFM) dengan perambatan ke atas. Kondisi ini menunjukkan bahwa gelombang Kelvin yang teramati pada lapisan tropopause dibangkitkan dari bawah. Gelombang Kelvin yang teramati dekat dengan sumber pembangkitnya.
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Kelvin waves that previously observed in the lower stratosphere in the Indian and western Pacific region. Indonesia’s position is between the two areas allowing the Kelvin wave in parts of Indonesia. However, the observed character is not necessarily the same. In JJAS period, the observed Kelvin waves have a period of 10-20 days meanwhile in DJFM period Kelvin waves detected on a period of 20 day. The Kelvin wave propagates eastward. The existence of a large convective activity in the territory of Indonesia is able to disrupt the Kelvin wave propagation. Convective clouds is shown by using the OLR data. In JJAS period, the strong disturbance in the earth’s north while in the DJFM period in equator. The existence of such disorders can increase the wind easterlies thus increasing the amplitude of the wave in the northern parts of the earth on the JJAS and southern parts of the earth on DJFM. From the analysis of the 500-150 mb layer, visible presence of 20 days oscillations (JJAS) and 10-20 days (DJFM) with upward propagation. This condition indicates that the Kelvin wave observed at the tropopause layer raised from the bottom. Kelvin waves are observed close to the sourcegenerator.
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