Jurnal Sains Dirgantara
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VARIASI KANDUNAGN UAP AIR DI ATAS KOTOTABANG, SUMATERA BARAT HASIL ANALISIS DATA RADIO ACOUSTIC SOUNDING SYSTEM (RASS) SELAMA KEGIATAN CPEA-CAMPAIGN 2004
Get PDFAs we know since June 2001, the National Institute of Aeronautics and Space (LAPAN) and Research Institute for Sustainable Humanosphere (RISH) of Kyoto University, Japan has already stared to make a joint research at LAPAN-Kototabang under the Coupling Processes Equatorial Atmosphere (CPEA) project. There are many research activities have already been dano by both institutes. One of them is the estimation of Total Precipitable Water (TPW) in the lower troposphere at Kototabang, West Sumatera (0.2ËšS; 100.32ËšE) during the CPEA I Campaign stared from April 10 to May 9, 2004 using many instruments. The main purpose of this paper is we would like to show how the TPW parameter can be estimated from the Radio Acoustic Sounding System (RASS) and radiometer and their correlation with the surface rainfall data. We applied the Wiesner (1970) technique when we estimated the TPW with specific humidity and air density taken from RASS and radiomater, respectively. Then, we analyzed the Cross-Correlation Function (CCF) when we compared the TPW and Optical Rain Gauge (ORG) data. In the same time, we analyzed the Boundary Layer Radar (BLR) data also to investigate the updraft and downdraft air mass activities from surface up to 5 km. We can see here the consistency of BLR, RASS and radiomater data when we investigated the vertical profile of water vapor over Kototabang. We found also a time variation of TPW, especially on April 24 and May 5, 2005 are about 0.43 and 0.35, respectively. Although both values look small relatively, but they are inough significant statistically
DINAMIKA ORBIT ASTEROID YANG ANALOG DENGAN ORBIT BUMI
Get PDFA set of asteroids that belong to Atens and Apollos groups which orbits are crossing the Earth at 1 AU is known as Earth-like-Orbit Asteroids. As of 1 July 2009, there were 19 Earth-like-Orbit Asteroids listed at the JPL (Jet Propulsion Laboratory – NASA) Small-Body Database. Orbital dynamics of five new asteroids among them (2008 EV5, 2008 JE, 2008 KT, 2008 UA202, and 2008 UC202) have not been studied yet. This study is important because they are asteroids belonging to potentially hazardous objects. High accuracy orbital integrations for a time-span of –1000 to +1000 yr have been conducted to figure out their evolutionary tracks. Our results show that high inclination Earth-like-Orbit Asteroids of more than ~5 degrees tend to be more dynamically stable than those of lower orbital inclination which often switch over from Atens to Apollos and vice versa. Four new Earth-like-Orbit Asteroids are found to have potential collisions with Earth because they will encounter the Earth at minimum distances of less than 0.01 AU. Keywords: Asteroids, Orbit dynamics, Hazardous object
PULAU PANAS PERKOTAAN AKIBAT PERUBAHAN TATA GUNA DAN PENUTUP LAHAN DI BANDUNG DAN BOGOR
Get PDFUrban development can affect climate element change, especially in downtown which is different from the surrounding, known as "Urban Heat Island (UHI)" phenomena. In this research we investigate air temperature changes on the land use and land cover by using case study in Bandung and Bogor on 1994 and 2001. We use the LANDSAT data of TM5 and ETM7 with spatial resolution of 30m x 30m, climate data from 1970-2003, and land use data from 1994-2003. The results shows that land cover causing the increase of temperature, i.e. residence, industry, and open land, were spreading. Consequently, UHI spreading over those area. Percentage of land use for residential area in Bogol was 11.3%, large than in Bandung (5.39%). Contrarily, larid cover causing the decrease of air temperature, i.e. high vagetation area (forest), seasonal plant, plantation, water badies, were decreasing. From the both investigated area, forest is decreasing, in Bogor the decrease 32.37% and Bandung 26.64%. Along with the changes of land use andland cover, so do air temperature changes. The increase of area related with air temperature in Bogor was 29.56% for temperature range (24-28)℃, while in Bandung was 21.79% for temperature range (24-29)℃. Area in Bandung having highest air temperature that increase was those with air temperature (28-29)℃, while in Bogor was those with air temperature (27-28)℃
KARAKTERISTIK INDIAN OCEAN DIPOLE MODE DI SAMUDERA HINDIA HUBUNGAN-NYA DENGAN PERILAKU CURAH HUJAN DI KAWASAN SUMATERA BARAT BERBASIS ANALISIS MOTHER WAVELET
Get PDFMakalah ini utamanya mengkaji karakteristik Indian Ocean Dipole Mode (IOD) yang ada di Samudera Hindia, khususnya dari parameter Sea Surface Temperature (SST) terhadap anomali curah hujan yang ada di beberapa kawasan yang ada di Sumatera Barat. Data IOD dan curah hujan bulanan yang kami gunakan dalam studi ini antara tahun 1960 hingga 1999 (selama 39 tahun pengamatan). Dengan menggunakan software minitab berbasis Principal Component Analysis (PCA), data curah hujan tadi dikelompokkan menjadi kelompok 1 hingga kelompok 3. Hasilnya menunjukkan bahwa ketiga kelompok curah hujan tadi ternyata memiliki osilasi dominan yang sama dengan data IOD, khususnya parameter SST sekitar 3 tahunan. Hal ini mengindikasikan bahwa kawasan Sumatera Barat yang relatif basah sepanjang tahun, diduga terkait erat dengan anomali SST yang ada di Samudera Hindia. Kata kunci : IOD, Curah hujan, Minitab, dan Analisis wavelet
PENGGUNAAN METODE ASPECT SENSITIVITY DALAM PENENTUAN TINGGI LAPISAN TROPOPAUSE DI SAAT MJO AKTIF MELINTAS KAWASAN KOTOTABANG DAN SEKITARNYA
Get PDFThis paper is mainly concerned to the utilization of aspect sensitivity (Pv/Po) method to define the tropopause height variation over the equatorial Indonesia, nearby Kototabang (0,2ËšS; 100,32ËšE), Bukittinggi, West Sumatera using the Equatorial Atmosphere Radar (EAR), especially during the Coupling Processes Equatorial Atmosphere (CPEA) Campign I in 2004 is already done. It is very important to be done since the tropopause is the buffer layer between troposphere and stratosphere (and also contrary) that usually called as the Stratosphere-Troposphere Exchanged (STE) (Holton, 1996). Validation's results with the radiosonde data shows that (Pv/Po relatively higher that radiosonde data. They are about 712 meter and 961 meter for Cold Point Tropopause (CPT) and Lapse Rate Tropopause (LRT) version, respectively. The mean difference between CPT and LRT itself is about 248 meter. This is enough valid considering to the maximum difference between of them not more 500 meter ( Haynes and Shepherd, 2001). This result then be applied in determining of tropopause height variation over Kototabang especially when the Madden-Julian Oscillation (MJO) passed over this region from November to December 2001. It shown that there are no significant differences between MJO active and no active on the tropopause height determination about 17.98 km and 17.73 km, respectively. The most interest is the tropopause height variation is larger during the MJO active than non active.To get the better understanding of tropopause height variation, especially with good time and spatial height resolution, the utilization of ERA and other instruments Kototabang are very needed
PERKEMBANGAN MODEL PREDIKSI INDEKS K GEOMAGNET
No full textPrediction model of daily K geomagnetic index was reconstructed based on K index pattern of 3-hourly data from Biak geomagnetic station during 1992. K index was observed according time sequence so that it is very complex, fluctuated, and without any pattern, due to stochastic properties. With such data, K index prediction model was analyzed based on the smoothing result by using a moving average of four data in time series analyzsis method through ARIMA (Auto Regressive Integrated Moving Average) model. The obtained prediction model of K index, from moving average of four data from the first 3 hours to the next eighth 3 hour, generally follow the ARIMA (2.0.0), ARIMA (2.0.1) and ARIMA (2.0.2) with very small error, less than 1((σ error than more 1) and the efficiency of 68.27%, 94.10% and 95.16%, respectively, during year 1996
PENETUAN RADIUS BULIR DARI FOTOMETRI ASTRONOMI: PERBANDINGAN TIGA METODE BERBASIS MODEL MIE
No full textThis paper discusses modeling steps of the total extinction coefficients,deduced from the astronomical photometric observations, to estimate aerosol perticulate size in the atmospheric layer. One important step in modeling is the application of Mie theory through Wempe's extinction law for aerosol and introduced by Angstrom (1929), i.e. The factor Qext is derived by elaborating Mie theory, through extinction efficiency factor which has been normalized, and an assumption that particle size is represented by a log-normal distribution. Final result of aerosol radius is deduced by fitting a decomposed observed extinction coefficient with that computed using the three Mie theory developed to estimate the best aerosol particulate's size
PENGARUH OZON TERHADAP HUJAN ASAM DI BANDUNG
Get PDFThe monthly of concentration of surface ozone at Dago (north Bandung) from January 2001 to June 2003 of 38.30 μg/m3. This value is higher than other four stations, Cisaranten Wetan and Aria Graha (East Bandung), Batununggal Indah (South Bandung) and Tegallega (Central Bandung) within variations 35.26-36.23 μg/m3. While SO2, NO2 gases, SO42-, NO3-, NH42+ ions, and pH of rainwater are measured at five locations, i.e. Cipedes (West Bandung), Martadinata (East Bandung), Dago (North Bandung), Kopo (South Bandung) and Kebon Kalap (Central Bandung) from August 2000-May 2003. The worst condition of acid rain was found at Cipedes with value of 5.09. This condition means that locations have been affected by acid rain in August 2000 - May 2003, because the value of pH less than 5.60 (the threshold of acid rain). Other locations such as Martadinata, Kebon Kalapa, and Kopo have average value of pH of 5.75, 5.95, and 6.00, respectively. While Dago which represents cleanest region of five locations in Bandung has average of pH of 6.06. The existence of zone have not influenced yet the deposition of acid rain in Bandung in general, especially at Dago, if we see the biggest value of correlation coefficient on that region of 0.64. The influence of ozone is more dominant to SO2 compared to NO2 based on acid deposition formed. The pollutant of SO2, No2 gases, and aerosol from the local source influences on concentration of sulfate and nitrate ions which have the important role on acid rain
IDENTIFIKASI PENGARUH AKTIVITAS MATAHARI PADA FOF2 DI BIAK DAN TEC IONOSFER DI BANDUNG
Get PDFThe identification of solar activity effets on ionospheric layer has been investigated based on data of monthly mean of critical frequency of ionospheric layer F2 (foF2) over Biak during the period 1991-1995, and data Total Electron Content (TEC) over Bandung during the period 1997-2000. Data of daily TEC over Bandung were used for identification of ionospheric storms due to large solar flares that occurred on September 23, 1998 and July 14, 2000 that followed by Coronal Mass Ejection (CME) event. From analysis it was found that solar activities such as sunspot and solar flare influences the ionospheric layer both short-term and long-term. By taking the moving average of 12 months and using linier regression analysis it was found that the variation of ionospheric foF2 and TEC following the variation of solar activity indices; the decreasing of solar activity during the descending phase of solar cycle-22 (1991-1995) is followed by the decreasing of ionospheric foF2 over Biak, with strong correlation coefficient of 0.96; the increasing of solar activity during the ascending phase of solar cycle-23 (1997-2000) is followed by the increasing of ionospheric TEC over Bandung, with strong correlation coefficient of 0.98. From identification of the large solar flares effects that occurred on September 23, 1998 and July 14, 2000 that followed by CME event causes the ionospheric storm about 2-days after solar flare. From identification also it seems that small solar flares no causes ionospheric storm in these period
THE POSSIBILITY OF UTILIZATION OF THE EQUATORIAL ATMOSPHERE RADAR (EAR) ON STUDY THE EFFECT OF GRAVITY WAVES ON A CORRUGATED STRUCTURE OF REFLECTION SURFACE
Get PDFWe have introduced a new Aquatorial Atmosphere Radar (EAR), a collaboration project between Research Institude for Sustainable Humanosphere (RISH), Kyoto University, Japan and the Indonesian Natioanal Institute of Aeronautics and Space (LAPAN) at Kototabang, Bukittinggi, West Sumatera. This radar is mainly concerned to observe winds and turbulence in the troposphere and lower stratosphere with a good time the EAR are still developing. In this paper, one possibility an application of EAR on study effects of gravity waves on a corrugated surface is discussed. For the referance, we investigated the azimuth angle variations of clear air echoes in the troposphere and lower stratosphere by using the MU (Middle and Upper Atmosphere) radar in Shigaraki, Japan (34˚51’N; 136˚06’E). We used a data set collected on November 4-5, 1986 by steering the antenna beam into 12 oblique positions at the same zineth angle of 6˚ and the azimuth angle being changed every 30˚. We have detected considerable amplitudes in the azimuth angle variations of echo power, which was continuous along altitude. We also found time evolution of the azimuth angle variations of echo power. The observed azimuth angle variations of echo power suggest that the reflection surface is affected by propagating gravity wave. As a preminary result, we present characteristics of zonal and meridional wind velocity observed with EAR on May 24-25, 2001 over Kototabang after observations of the variations of meridional wind velocity from September to December 2001 as one of the most important parameter needed to explain the mechanism of gravity waves is also discussed