Jurnal Sains Dirgantara
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TELAH ORBIT SATELIT LAPAN-TUBSAT
No full textThe study of orbit characteristics of LAPAN-TUBSAT can be done by using some microsatellites which identical in the case of mission and its orbit. This knowledge is usefull to reduce the failure of mission. This characteristics can be seen from the change of orbital elements caused by perturbation forces. LAPAN-TUBSAT is placed in Low Earth Orbit (LEO) at altitude about 630 km which has orbit near polar (i≈98˚). At this altitude, the perturbations come from non-gravitation force such as atmospheric drag and gravitation force from earth oblatness. From the simulation can be predicted that in the early years of its operation, the variation in altitude and semi major axis is relatively small. The means that this satellite could have the life time more than 50 years. The effect of earth oblatness will cause the regression of the nodes of about 1˚/day and the rotation of the line of apsides of about -3˚/day. These changes are not too critical for near polar orbit which means that satellite keeps conducted the mission goal such as satellite imaging
PENGARUH AKTIVITAS MATAHARI PADA VARIASI CURAH HUJAN DI INDONESIA
Get PDFAktivitas matahari dapat mempengaruhi parameter iklim jangka panjang. Radiasi ultraviolet, radiasi tampak (visible) dan radiasi panas adalah faktor utama yang mempengaruhi parameter iklim bumi. Radiasi-radiasi ini bervariasi mengikuti variasi aktivitas matahari dengan periode sekitar 11 tahun. Penelitian pengaruh aktivitas matahari pada variabilitas curah hujan di atas Indonesia selama 105 tahun (1900-2005) dilakukan dengan analisis wavelet dan korelasi empirik pada data variasi tahunan curah hujan, musim Jurnal Sains Dirgantara Vol. 5 No. 2 Juni 2008:149-168 150 DJF dan JJA yang telah dikelompokkan dengan metode fuzzy clustering. Melalui kombinasi metode fuzzy clustering, wavelet, dan metode korelasi memperjelas bahwa curah di Indonesia dipengaruhi oleh aktivitas matahari jangka panjang. Kesamaan periodisitas curah hujan dengan aktivitas matahari, terutama periode -11 dan 22-tahun, merupakan indikasi pertama pengaruh aktivitas matahari pada variabilitas iklim Indonesia. Dari hasil analisis keterkaitan antara bilangan sunspot dan curah hujan dengan menggunakan pemulusan rata-rata bergerak 11 tahun dari rata-rata tahunan, curah hujan cenderung mengikuti pola variasi aktivitas matahari jangka panjang walaupun variasi curah hujan ada yang sefasa dan yang mendahului, variasi bilangan sunspot berkisar 15-20 tahun. Sementara itu, hasil analisis menunjukkan bahwa variasi curah hujan di cluster Indonesia Barat mempunyai korelasi yang baik dengan aktivitas matahari jangka panjang dengan indikator panjang siklus matahari sekitar 11 tahun, dan koefisien korelasinya mencapai r = 0,75. Sedangkan variasi curah hujan di cluster Indonesia Timur memiliki korelasi yang baik dengan variasi siklus matahari-11 tahun dan koefisien korelasinya bisa mencapai 0,81. Kata kunci : Variabilitas curah hujan, Aktivitas matahari, Panjang siklus matahari, Fuzzy Clustering
PERUBAHAN KLIMATOLOGIS CURAH HUJAN DI DAERAH ACEH DAN SOLOK
Get PDFThe analysis of rainfall climatologic change of Aceh and Solok area using 103 years (1900-2003) data for wet season (DJF) and dry season (JJA) have been done. The result show that for Aceh area, for wet season (DJF) the maximum rainfall was 664 mm/month in 1926, which was in the normal condition. And for dray season (JJA) the rainfall condition for periods JJA-7. (1961-1990), JJA-8 (1971-2000) and JJA-9 (1981-2003) were under normal condition. For Solok area the maximum rainfall was 1972 mm/mounth in 1972, the rainfall condition for wet season (DJF) and dry season (JJA) are in the normal condition
ANALISIS EVOLUSI GRUP SUNSPOT SPD WATUKASEK UNTUK MEMPEROLEH INDIKATOR KEMUNCULAN FLARE
Get PDFIn their evolution, sunspot groups change in its number, area, shape and its formation. Proper motion of sunspot group show twist and shear movement. Therefore, we measure the central position it preceding and following parts. The difference of angle between the preceding and following part in the evolution on (n + 1) thand n may indicated that in its evolution the sunspot group have changed the area. We suggest some indications for predicting flare using the maesurement of twist and shear of the spot in a group
ANALISIS DATA BLR DAN EAR DALAM MENGKAJI FENOMENA MJO DAN KETERKAITANNYA DENGAN CURAH HUJAN DI ATAS KOTOTABANG DAN SEKITARNYA
Get PDFThis paper is mainly concerned to the analysis of Madden Julian Oscillation (MJO) phenomena crossing over Kototabang, West Sumatere and surrounding areas using Boundary Layer Radar (BLR) and Equatorial Atmosphere Radar (EAR) data taken from September to December 2001 as cintinuing studied by Indriaty (2005). We are interested to continue, especially on the effect of MJO phenomena on the daily rainfall intensity distribution over Kototabang and surrounding area. We divided data into two steps analysis. First is the vertical profile analysi using BLR and EAR data, and the second step is surface analysis using RAINFALL INTENSITY DATA FROM TAKEN FROM THREE METEOROLOGICAL STATIONS IN wEST sUMATERA. tHEY ARE bADAN mETEOROLOGI DAN gEOFISIKA (bmg) Sicicin station (0.6ËšLS; 100.22ËšBT), BMG-Padangpanjang station (0.5ËšLS; 100.41ËšBT) and Statsiun Pengamat Dirgantara (SPD) LAPAN Kototabang (0.2ËšLS; 100.32ËšBT). The vertical profile of zonal-vertical wind vector of EAR data analysis shows that the pre-dominant wind mived to east direction, especially in surface layer, while in the upper troposhere the pre-dominant wind moved to the opposite direction, especially from September to December 2001. This result looks a siminar with the schematic theory of the MJO cross section along equator that described by Matthews (2000). A simiinar result is also shown by the BLR data analysis. Both EAR and BLR data are siminar each other. Since the MJO phenomena is expected passing over Kototabang around mid of November to mid of December 2001, we are interested to analysis the as already mentioned above using the global wavelet spectrum technique. The result shows that their pre-dominant peak ascillation is about 48 days. This result is consistent with the Outgoing Longwave Radiation (OLR) anomaly taken from infra-red sensor of satellite that already been done by Matthews (2000). While, the cross correlation function (CCF) analysis between zonal wind and rainfall data shows unsignificant (very small) value. We suspect that the surface rainfall intensity over Kototabang and surrounding area is not mainly dominanted by MJO phenomena
ANALISIS VARIASI DIURNAL OZON DAN PRECURSORNYA PADA MUSIM KEMARAU DAN MUSIM HUJAN DI BANDUNG
Get PDFATelah dilakukan pengukuran konsentrasi NOX (NO +NO2) dan CO ambien secara kontinyu sejak awal tahun 2008 di Bandung (06º, 54†S,-107º, 35†E, 762 m DPL). Pengukuran ini merupakan bagian dari program pengembangan kapasitas pemantauan kualitas udara ambien, sementara pengukuran konsentrasi ozon ambien telah dilakukan secara kontinyu sejak Jurnal Sains Dirgantara Vol. 7 No. 1 Desember 2009 : 165-175 166 tahun 1985. Analisis data ozon dan prekursornya, NOX (NO +NO2) serta CO tahun 2008 untuk musim kemarau dan musim hujan juga dilakukan. Diperoleh puncak konsentrasi variasi diurnal NOX dan CO terjadi pada pagi hari antara pukul 06.30-07.30 WIB, dan sore hari antara pukul 19.00-21.00 WIB, puncak konsentrasi ini menggambarkan karakter hubungan fotokimia proses pembentukan dan perusakan ozon. Secara berturut-turut diperoleh nilai konsentrasi rata-rata NOX, NO, NO2, CO dan O3, NOX: 19,23 ppbv, NO: 8,89 ppbv, NO2: 10,14 ppbv CO: 930 ppbv dan O3: 20,91 untuk musim kemarau dan NOX: 25,18 ppbv, NO: 11,35 ppbv, NO2: 13,81 ppb CO: 1104 ppbv and O3: 23,67 ppbv untuk musim hujan. Nilai maksimum konsentrasi O3 mencapai 54,65 ppbv pada pukul 12.00 WIB di musim kamarau dan 36,51 ppbv pada pukul 11.00 WIB di musim hujan, sementara nilai minimum konsentrasi terjadi pada awal pagi hari sebesar 9,24 ppbv pada pukul 05.00 WIB pagi untuk musim kamarau dan sebesar 11,7 ppbv pada pukul 01.00 WIB untuk musim hujan. Terjadinya peningkatan konsentrasi O3 sepanjang pagi hari bertepatan dengan penurunan konsentrasi NO karena proses fotolisis, sementara penurunan kosentrasi O3 pada sore hari kemungkinan merupakan hasil dari proses deposisi kering bersamaan dengan penurunan lapisan batas dan adanya tritrasi dengan NO, karena melemahnya proses photokimia sepanjang sore hari. Diperoleh nilai background konsentrasi CO terhadap NOX pada musim kemarau sebesar 219,74 ppbv, sementara nilai background konsentrasi CO pada musim hujan sebesar 176,86 ppbv, dengan koefisien korelasi lebih besar dari 90 % untuk kedua musim baik musim kemarau maupun musim hujan. Kata Kunci: Ozon, Precursor ozon, Variasi diurnal, Laju fotolisis, Fotokimia
PENGELOMPOKAN WILAYAH CURAH HUJAN KALIMANTAN BARAT BERBASIS METODE WARD DAN FUZZY CLUSTERING
Get PDFIn order to decrease the climate information gap, the rainfall clustering based on the TRMM data is presented. Then, the rainfall pattern could be determined for all region. Using the principal component analysis as the interface, clustering analysis, namely the Ward and the Fuzzy Clustering methods, the rainfall in West Kalimantan could be grouped in to four clusters according to its homogenity. The first cluster consists of grids that gather in the Karimata strait, Java Sea, and some area in West Kalimantan Lands. The second group was built by grids in the land with homogeneous topography. The third group in the middle of West Kalimantan was a cluster in the land which has different elevation. The fourth group was a cluster in the northern Kalimantan and close to the South China Sea. The West Kalimantan rainfall derived from the TRMM data has the equatorial and monsoonal patterns. The monsoonal pattern was exhibited by the cluster in the ocean (first cluster), and the equatorial pattern was showed by clusters in the land (second, third, and fourth clusters). The equatorial rainfall pattern revealed that the first wet month occuring in April, whereas the second wet month occured in December or January. The month with lowest rainfall is August. Key word: Rainfall pattern, Rainfall cluster, Ward and Fuzzy Clustering method
VARIASI LAPISAN E DAN F IONOSFER DI ATAS KOTOTABANG
Get PDFPengamatan ionosfer di atas Kototabang (0,2ºLS, 100,3ºBT) dilakukan menggunakan ionosonda Frequency Modulated Continous Wave (FMCW) yang dioperasikan sejak Maret 2004. Hasil pengamatan sampai dengan September 2006 diteliti untuk mengetahui variasi ionosfer di daerah tersebut. Hasilnya menunjukkan bahwa secara umum variasi ionosfer di atas Kototabang mengikuti pola karakteristik ionosfer di daerah lainnya di Indonesia. Variasi harian menunjukkan maksimum sekitar tengah hari, variasi tahunan nampak dari penurunan nilai foE, foF1, dan foF2 seiring berkurangnya tingkat aktivitas matahari. Hal ini diperkuat dengan korelasi positif yang diperoleh antara rata-rata median bulanan foE, foF1, dan foF2 pada local noon (pukul 10.00 – 15.00), dengan koefisien korelasi masing-masing 0.64, 0.90, dan 0.80. Variasi musiman nampak dari adanya dua puncak (Maret- April dan September–Oktober), dan dua minimum (Juli-Agustus dan Desember–Januari). Badai magnet yang terjadi pada tanggal 15 Mei 2005 mengakibatkan penurunan foF2 sebesar 5.5 Mhz atau 38% dibandingkan harga median bulanannya, sekitar 5 jam setelah terjadinya badai tersebut. Kata kunci : Ionosfer, Variasi, Lapisan E, Lapisan F
ANALISIS PERGERAKAN BINTIK MATAHARI DI DAERAH AKTIF NOAA 0375
Get PDFThe observation of flaring sunspots group (active region) has been conducted to obtain the characteristic of spot's motion. In active region NOAA 0375 the motion is divided in two periods, 3-8 June 2005, when the group was growing, and 10-12 June 2003 when it was decaying. By comparing the movement plots, we see that the strong flares were most produced when the active region was in the decaying phase