Jurnal Sains Dirgantara
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KETIDAKTERATURAN LAPISAN IONOSFER DAN KAITANNYA DENGAN PROSES-PROSES KOPLING ATMOSFER-IONOSFER INDONESIA [IONOSPHERIC IRREGULARITIES AND ITS RELATION TO COUPLING PROCESS OF ATMOSPHERE-IONOSPHERE OVER INDONESIA]
Full text linkKetidakteraturan ataupun ketidakstabilan plasma di lapisan ionosfer perlu dijelaskan mekanismenya sehingga akan bermanfaat dalam pembangunan maupun pengembangan model lapisan ionosfer. Dengan memanfaatkan teknologi penginderaan jauh, dalam hal ini adalah radar MF, Radar Atmosfer Ekuator (EAR), dan GNU Radio Beacon Receiver, sinyal-sinyal keluarannya diolah untuk mendapatkan parameter dinamika atmosfer-ionosfer. Hubungan antara ketidakteraturan lapisan ionosfer berupa Equatorial Spread F (ESF) dengan proses dinamis yang terjadi di lapisan atmosfer bawah dapat dijelaskan melalui mekanisme penjalaran gelombang gravitas dari atmosfer bawah ke atmosfer atas. Selain itu ditemukan juga adanya proses kopling antara lapisan E dan lapisan F yang berperan dalam terbentuknya ketidakteraturan lapisan ionosfer tersebut. Hasil lainnya menunjukkan adanya keterkaitan antara aktivitas matahari dengan ketidakteraturan di lapisan ionosfer dengan munculnya Equatorial Spread F (ESF) malam hari di wilayah ekuator Indonesia. Kata Kunci: Equatorial Spread F (ESF), Kopling lapisan E dan
AWAN MAGNET PADA FASE MINIMUM AKTIVITAS MATAHARI DAN KAITANNYA DENGAN GANGGUAN GEOMAGNET
Full text link Interplanetary structures are important for the development of geomagnetic disturbance. The structures include intense north-southward Interplanetary Magnetic Field, the shock, solar wind density and velocity, and probably the magnetic cloud. We studied five events of magnetic clouds which occurred in the minimum phase of solar activity in order to understand solar wind-magnetosphere coupling. The correlations between storm intensity and the different solar wind parameters will also be presented as well. By analyzing five magnetic clouds occurred in 2006 and the associated geomagnetic enhancement, we found that not all magnetic clouds lead to geomagnetic disturbances. Keywords:Magnetic cloud, Interplanetary magnetic field, Geomagnetic disturbanc
ANALISIS ASOSIASI SEMBURAN RADIO MATAHARI TIPE III DENGAN FLARE SINAR-X DAN FREKUENSI MINIMUM IONOSFER
Full text link The type III solar radio bursts is an indicator of solar X-ray flare phenomena. The effect of solar X-ray flares to the ionospheric layer is the increasing of minimum frequency (fmin) which indicates the absorption of incoming high frequency (HF) radio wave. Further impact is a disturbance of high frequency radio communications. The number and flux density of type III bursts and X-ray flare can used as an information of ionospheric disturbance possibility. The correlation analysis shows that the number of X-ray flare is related to the number of ionospheric absorption and the time duration of these absorption. The serial event of type III bursts and solar X-ray flare occures during February 6th to 12th, 2010 are an example cases of the early warning of possibility of radio communications disturbances. Key Words:Solar radio bursts, X-ray flare, Radio communication disturbanc
POTENSI KEJADIAN BADAI GUNTUR BERDASARKAN PARAMETER KELEMBAPAN, LABILITAS UDARA, DAN MEKANISME PENGANGKATAN (STUDI KASUS: DI BANDAR UDARA FRANS KAISIEPO BIAK)
Full text link Thunderstorms is a weather condition that is harmful to the flight activities. The potential thunderstorms (especially thermal thunderstorms) assesment for Indonesia in particular Biak area needs to be done to reduce the risk of bad thunderstorms to flight activity at airports Frans Kaisiepo Biak. The thunderstorms is affected by the existence of water vapor in the atmosphere. The content of water vapor in the atmosphere can be estimated from the value of precipitable water, while atmospheric instability conditions can be identified from the Convective Available Potential Energy (CAPE), assuming an air parcel at the surface is heated until it reaches the temperature of the convective (TC) so that air parcels can be lifted up to convective condensation level (CCL) and it condensate. Logistic regression is one of mathematical models approach that can be used to describe the relationship between the independent variables with response variables that are bound dikotomik (event and non-event). By using observation data of surface and upper air in 2006-2009 analysis of air instability and its relation to the probability of thunderstorm occurrence is carried out. Results show that precipitable water between surface and 300 hPa height has correlation and directly proportional to the probability of thunderstorm occurrence, and convective temperature (TC) has correlation and inversely proportional to the probability of thunderstorm occurrence. While CAPE at CCL to 300 hPa height has not correlation to the probability occurrence of thunderstorms. Thunderstorm probability model has 58.8% of accuracy. Keywords:Thunderstorms, Precipitable water, Convective temperature, CAPE, Logistic regressio
PENGARUH SOLAR PROTON EVENT JANUARI 2005 TERHADAP PENIPISAN OZON STRATOSFER DI INDONESIA
Full text linkOzone data from Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) Aura satellite were used to investigate the impacts of the very intense Solar Proton Events (SPE) 15-25 January 2005 on the stratospheric ozone in Indonesia. From the ozone vertical profiles along the SPEs period, the decreasing of ozone concentration was observed after the peak of the SPEs. This ozone decrease was associated with the increase of NO2 and HO2 concentration which was produced due to the ionization by the energetic protons. The ozone decrease was also identified by analyzing the spatial column amount ozone in Indonesia. The ozone decrease after the SPEs was about 8 percent from the average of daily column amount ozone before the SPEs. The very high energetic protons from the SPEs were suspected to be responsible for the possibility of the proton precipitation into the low latitude regions. Keywords: Solar Proton Event, Stratospheric ozone depletion, Low latitude proton precipitationÂ
STOCHASTIC PROCESS IN THE TIME SERIES MODEL OF PACIFIC DECADAL OSCILLATION (PDO)
Full text linkPacific Decadal Oscillation (PDO) is long-lived El Niño-like pattern of Pacific climate variability generated by coupled ocean-atmosphere interaction in the Northern Pacific Ocean. The best way to acquire a signal of PDO evidence is by determining the index of PDO. In this study, the PDO indexes are accurately modeled with time series methods through exponential smoothing analysis (Single and Holts Double exponential smoothing model) and Box-Jenkins analysis (ARIMA {1,1,1}, {2,1,1}. {3,1,1} and {4,1,1}). Nicholas’s PDO Model (ARMA 9, 7) is also considered as comparative model in order to obtain the level of the reliability models that have been produced. The best selected prediction model that close to the real PDO index is ARIMA (2,1,1) Zt = 1.574* Zt-1 -0.427* Zt-2 -0.147* Zt-3 -0.976* at-1 which means the forecast of PDO in the future depending on three months earlier data and a month earlier error of PDO index. Mean absolute error (MAE) of this model is 0.5283 and with root mean square error (RMSE) 0.6661. The predicted and observed PDO indexes are significantly correlated with r =0.76. Keywords: PDO, Box-Jenkins analysis, Exponential smoothing analysisÂ
KARAKTERISTIK PETIR DARI AWAN KE BUMI DAN HUBUNGANNYA DENGAN CURAH HUJAN
Full text link This paper describes the relationship between CG (Cloud to Ground) lightning and the rainfall of Bandung and surrounding area. CG lightning data obtained by Lightning Detector that is able to track low frequency of radio signals from electrical processes lightning discharge which installed in Bandung Geophysics Station. For better resolution, data is limited within a radius of 10 km square of study area. Daily analysis during the year 2009 showed a strong relationships between CG and rainfall (r = 0,62 for CG+; r = 0,51 for CG- and r = 0,59 for total of CG). The electrification process dominated by CG- and the peak of CG occurs at MAM with the 43,6% total of CG and occurs at 15.00-17.00 LT. The mature stage occured after 13.00 LT. Keywords:Lightning, CG, Rainfall, Relationshi
ANALISIS KONDISI ANTARIKSA DI ORBIT LAPAN A2 MENJELANG PUNCAK AKTIVITAS MATAHARI SIKLUS 24
Full text link LAPAN A2 satellite will be placed at 650 km altitude and inclination of 8 at the beginning of year 2012 based on the initial scenario. This satellite has structure with the size and weight are 60 cm x 60 cm x 80 cm and 65 kg consecutively. Space environment analysis on this satellite using space weather pattern method showed that geomagnetic activity levels, represented by Kp and Dst indices, had range of 2 to 4 and -40 to -9 nT consecutively. It means that the effect of geomagnetic activity will not significantly impact the satellite system. Simulation using SPENVIS also showed small impact of proton and electron on satellite structure. Analyzing on atmospheric drag showed that this satellite has stable orbit. The only possibility of LAPAN A2 satellite experiences charging come from charged particles trapped in South Atlantic Anomaly (SAA) that contain high flux of particles. Keywords:LAPAN A2 Satellite, Geomagnetic, Particl
PENGARUH IONOSFER PADA AKURASI PENENTUAN POSISI ABSOLUT DENGAN GPS SINGLE FREQUENCY PADA SAAT TERJADI BADAI MATAHARI
Full text linkThe effect of the ionosphere on the propagation of signals emitted from GPS satellites at an altitude of about 20,000 km is in the form of code delay or carrier advance of the signal propagation time which depends on the Total Electron Content (TEC) and the GPS signals frequency. Coronal Mass Ejections (CMEs) occurred during October 28 and 29, 2003 solar storms have caused ionosphere disturbances called ionospheric storms. The ionospheric storms have degraded the accuration of single frequency GPS absolute positioning to more than 400%. Mitigation of ionospheric storms effect on the single frequency GPS absolute positioning by using Klobuchar model can not produce a significant increase in accuracy. Hence during the ionospheric storms, the regional ionospheric TEC model is needed for ionospheric correction of single frequency GPS absolute point positioning. Keywords: Solar storm, Ionosphere, Radio wave, Propagation, Positioning, Accuratio
KLASTER CURAH HUJAN TRMM RATA-RATA 3 JAM-AN DAN HUBUNGANNYA DENGAN FENOMENA ATMOSFER
Full text linkThree hourly Tropical Rainfall Measuring Mission (TRMM) rainfall data availability provides an opportunity to study more deeply in short time atmospheric process, as is presented in this paper. Arithmatic mean value of rainfall is used to eliminate micro and local factors. Clustering with annual average data show the number of clusters varies from 6 to 14. The number of the smallest cluster of 6 occurred in 2004, while the number of the highest clusters found in 2010. Identify the relationship of 3-hourly rainfall clusters with an atmospheric phenomenon carried out by evaluating the correlation between the number of clusters with Sea Surface Temperature (SST) anomalies in the Pacific and Indian oceans. The results showed clusters number unrelated to SST anomaly in Indian ocean and linearly related to SST anomaly in the Pacific ocean when SST anomalies in the ocean are changing the three hourly accumulative rainfall. Key words:Three hourly, Rainfall, Cluster, SST anomal