SIMULASI KESEIMBANGAN ENERGI PERMUKAAN DI JAKARTA DAN SEKITARNYA MENGGUNAKAN MODEL NUMERIK MM5

Abstract

Studi simulasi keseimbangan energi permukaan di Jakarta dan daerah sekitarnya menggunakan model numerik Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) telah dilakukan. Empat domain dengan resolusi spasial 9 km yang menggambarkan daerah Jakarta dan sekitarnya disimulasikan selama 5 hari pada tanggal 04-08 Agustus 2004 untuk memperoleh hubungan radiasi dan keseimbangan energi di wilayah tersebut. Hasil menunjukkan bahwa keseimbangan energi lebih tinggi pada siang hari terjadi di perkotaan dibandingkan daerah lainnya. Sementara itu, komponen energi seperti fluks bahang terindera dan laten di permukaan masing-masing menunjukkan bahwa wilayah laut dan perkotaan lebih tinggi daripada daerah lainnya. Sebaliknya, fluks bahang tanah menunjukkan daerah rural di bagian timur Jakarta lebih tinggi dibandingkan daerah lainnya. Secara umum, keseimbangan radiasi dan energi pada siang hari lebih tinggi daripada malam hari di seluruh daerah. Rasio Bowen di wilayah kota yang mencerminkan kawasan bangunan dan perkotaan lebih tinggi daripada di daerah rural yang didominasi oleh lahan pertanian beririgasi. Hal ini sesuai dengan perubahan sifat fisik tutupan lahan seperti albedo, kelembaban tanah dan karakteristik bahang.

A study of surface energy balance simulation in Jakarta and surrounding areas by using Fifth-Generation Penn State/NCAR Mesoscale Model (MM5) numerical model was done. Four domains that presented the outermost and the innermost of Jakarta and surrounding areas were utilized. All domains have spatial resolutions of 9 km. The model was simulated for 5 days on August 4-8, 2004. The relation of radiation and energy balance at the surface was derived from the model output. The result showed that the energy balance was higher in the city during the daytime. Meanwhile, the energy component, i.e., surface sensible and latent heat flux showed that sea and city were higher than others, respectively. Moreover, ground flux showed the eastern rural area was higher than others. In general, radiation and energy balance was higher during daytime and lower in the nighttime for all areas. The calculation of the Bowen ratio was also higher in the city that reflected the urban and built-upland. Meanwhile, the Bowen ratio in the rural area dominated by irrigated cropland was lower than the city. It is consistent with changes in land cover properties, i.e., albedo, soil moisture, and thermal characteristics.