Analisis Dinamika Atmosfer di Bagian Utara Ekuator Sumatera Pada Saat Peristiwa El-Nino dan Dipole Mode Positif Terjadi Bersamaan  

Oleh:

Harijono, Sri Woro B.

Jenis: Article from Journal - ilmiah nasional
Dalam koleksi: Jurnal Sains Dirgantara vol. 5 no. 2 (Jun. 2008), page 130-148.
Topik: ENSO; Indian Ocean Dipole Mode (IODM); Sirkulasi Walker; Sirkulasi Hadley; PW; Tutupan Awan

Ketersediaan

Perpustakaan Pusat (Semanggi) Nomor Panggil: SS49.1 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

Analysis of persisten normal to above normal of rainfall characteristic in north part of Sumatera during period of June-July-August (JJA) at the El Nino and positive phase of Dipole Mode (DM+) events occure simultaneously have conducted using several atmospheric parameters, namely precipitable water, cloud cover, and Outgoing Longwave Radiation (OLR). The East-West and North-South circulation which is the mode of water vapour transport to the these region is depicted as the zonal and meridional circulation map. When the DM+ and El Nino events occured simultaneously (1963, 1973, 1982 and 1997), they will causes shifting the circulations away from Indonesia region to the central Pacific Ocean as the impact of El Nino and to the west part of India Ocean as the impact of DM(+). The dynamic of water vapour mass flow processes experience an anomaly hence the rainfall in the most south part of Indonesia decrease. But in the north part of Sumatra Island (Aceh-Medan-Lhokseumawe-Meulaboh), during JJA period the rainfall characteristics is high than average. This matter because of there is still available of water vapor around research region identified from parameter of OLR, precipitable water, cloud cover as well as the existence of water vapor mass transport mechanism to the region identified as the India Monsoon. More detailed result of rainfall analysis indicates that the rainfall characteristic in Medan and Lhokseumawe does not significant compared to Aceh and Meulaboh. This is caused by local factor like geography position and of local circulation which playing an important role in lifting of air mass/convection and in function of forming mechanism of rainfall in the tropical zone. The geographical position of Medan and of Lhokseumawe residing behind the Bukit Barisan mountain become leeward during period of JJA. So that the rainfall although is high than average but it is not significant, whereas Aceh and Meulaboh which located in the front of the Bukit Barisan mountain become area of windward at this period and has a significant of above normal rainfall.

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