Identifikasi Kejadian Siklon Tropis di Perairan Sekitar Indonesia dari Observasi Satelit TRMM (Tropical Rainfall Measuring Mission) dan Kaitannya dengan Curah Hujan
Study of Identification a Tropical Cyclone Phenomenon at Indonesia Surrounding from TRMM (Tropical Rainfall Measuring Mission) Satellite Observation and Its Relation with The Rainfall.
Abstract
Tropical cyclone is a cloudy circular system which occurs an extreme wind and rainfall through its atmosphere area. Commonly, it is formed both tropic's area and 4 degree scale latitude above sea atmosphere. Although it is rarely formed in Indonesian surroundings, but its impact often affects the several area of Indonesia one of them like, the rainfall cycles occur significantly. This main goal of this research is to identify a frequency appearance of its cyclone of the surrounding nearest area with Indonesian such as; West Pacific Ocean, South Indian and Bay of Bengal during six years start from 2006 to 2011. It's also including an observe the characteristics of the potential rainfall, and it's affected spatially (horizontal) and temporally on it systems. The observation was done by using the observation satellite data of TRMM (Tropical Rainfall Measuring Mission). The rainfall is observed from the result of analysis 3B42 data, with 0,25ox0,25o spatial resolution and three hourly temporal resolution. The result has shown that totally of tropical cyclone frequency for that time It most occurred in 2007 and 2008, mainly; it has occurred at West Pacific. It is often existed during the summer in each related area that following ITCZ (InterTropical Convergence Zone). More than 50% of them are formed in the 10 – 20 degrees of North/South Latitute, the area which is coriolis force and the sea-surface temperature optimum for it formed. If it had more intents, both rainfall and spatial would be increasing more regularly. The highest potency of rainfall is occurred when the cyclone be adult, and it will be decreased if the cyclone is too low. Commonly, all the cyclones have a spatial rainfall distribution which is decreased gradually from the cyclone to its outer wall even though, it sometimes doesn't well-run on depression rainfall stage. The effect of the rainfall usually occurs a tale of its cyclone or cloudy separation dispersion at the beginning of cyclone formation. Siklon tropis merupakan sistem perawanan sirkuler yang menimbulkan angin dan curah hujan ekstrem pada daerah yang dilaluinya. Umumnya terbentuk di wilayah tropis dan di atas lautan hangat dalam skala luas di atas lintang 4o. Meskipun siklon tropis jarang terbentuk tepat di wilayah Indonesia, namun dampaknya seringkali mempengaruhi sebagian wilayah Indonesia salah satunya menyebabkan perubahan curah hujan yang cukup signifikan. Penelitian ini bertujuan untuk mengidentifikasi frekuensi kemunculan siklon tropis di wilayah perairan paling dekat dengan Kepulauan Indonesia yaitu perairan Pasifik Barat, Hindia Selatan, dan Teluk Benggala selama selang waktu 6 tahun dari tahun 2006-2011 serta mengamati karakteristik sebaran potensi curah hujan secara spasial (horizontal) dan temporal pada sistem siklon tropis dan dampaknya di wilayah Indonesia. Pengamatan kemunculan siklon dan curah hujan dilakukan dengan menggunakan data hasil observasi satelit TRMM (Tropical Rainfall Measuring Mission). Sebaran curah hujan diamati dari hasil pengolahan data 3B42 dengan resolusi spasial 0,25ox0,25o dan resolusi temporal 3 jam-an. Hasil pengamatan menunjukkan bahwa frekuensi siklon tropis total selama selang waktu tersebut paling banyak terjadi di tahun 2007 dan 2008 sebagian besar terjadi di Pasifik Barat. Siklon tropis kebanyakan muncul pada saat summer di masing-masing wilayah kajian mengikuti pola ITCZ (InterTropical Convergence Zone). Lebih dari 50% kejadiannya terbentuk di lintang 10-20 derajat Utara/Selatan, wilayah dimana gaya coriolis dan suhu muka laut paling optimum untuk pembentukan siklon tropis. Semakin kuat siklon tropis maka potensi curah hujannya semakin tinggi dan distribusi spasialnya semakin teratur. Potensi curah hujan paling tinggi terjadi saat siklon dewasa dan akan menurun jika siklon melemah. Secara umum semua tahapan siklon memiliki distribusi spasial curah hujan yang menurun secara bertahap dari pusat siklon ke arah dinding terluar siklon, meskipun kadang pada tahapan depresi sebaran hujan cenderung tidak teratur. Curah hujan yang terjadi di wilayah Indonesia pada saat kejadian siklon biasanya akibat dampak dari ekor siklon atau pemencaran awan pada tahap awal pembentukan siklon.