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ANALISIS DATA BLR DAN EAR DALAM MENGKAJI FENOMENA MJO DAN KETERKAITANNYA DENGAN CURAH HUJAN DI ATAS KOTOTABANG DAN SEKITARNYA Eddy Hermawan; Arief Suryantoro; Mega Puspawardhany; Tri Wahyu Hadi; Udjianna S. Pasaribu; Findy Renggono
Jurnal Sains Dirgantara Vol 4, No.1 Desember (2006)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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This 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 (0.6˚LS; 100.22˚BT), BMG-Padangpanjang station (0.5˚LS; 100.41˚BT) and Statsiun Pengamat Dirgantara (SPD) LAPAN Kototabang (0.2˚LS; 100.32˚BT). 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.

ESTIMASI PARAMETER TURBULENSI UNTUK JASA PENERBANGAN BERBASIS HASIL ANALISIS BEBERAPA DATA RADIOSONDE DI KAWASAN BARAT INDONESIA Eddy Hermawan; Zainal Abidin
Jurnal Sains Dirgantara Vol 3, No.2 Juni (2006)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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The one of an important thing related to the aviation is the correct information of aviation meteorology, especially about bad weather condition such as turbulence that often disturb the plane during their flight. There are many parameters to estimate the turbulence parameter. One of them is called the Richardson Number (Ri) such as already investigated by Waco (1970). We continued hos study by applying the radiosonde data distributed at five stations in the Western part of Indonesia region, especially during the Coupling Processes Equatorial Atmoephere I (CPEA I) Campaign started from April 10 to May 10, 2004. We defined the turbulence when Ri less more 0.25 as described by Killer (1981). We found initial turbulence occurrence indication, even though we have found significant indication yet, related with less of locations and data observations which is only one month observation. Turbulance in the plane is described as the changes of vertical gravitation in the plane and observed by vertical accelerometer which is installed in the plane. After making some validations with the vertical accelerometer data, we found only a few good correlation between Ri and turbulence. We suspect it caused by the less of data observation. But initial indication based on data analysis shows that light turbulence occurrence a long Eastern Coast of Malacca Peninsula on 19th April 2004.

THE POSSIBILITY OF UTILIZATION OF THE EQUATORIAL ATMOSPHERE RADAR (EAR) ON STUDY THE EFFECT OF GRAVITY WAVES ON A CORRUGATED STRUCTURE OF REFLECTION SURFACE Eddy Hermawan
Jurnal Sains Dirgantara Vol 2, No.2 Juni (2005)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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We 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.

ANALISIS VARIABILITAS CURAH HUJAN DI SUMATERA BARAT DAN SELATAN DIKAITKAN GENGAN KEJADIAN DIPOLE MODE Eddy Hermawan; Sopia Lestari
Jurnal Sains Dirgantara Vol 4, No 2 (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

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The rainfall variability over the Western and Southern part of Sumatera Island related to te Dipole Mode (DM) event for period of twenty years (1980-1999) based on the monhly mean of rainfall, Dipole Mode Index (DMI), Sea Surface Temparature (SST), and Outgoing Longwave Radiation (OLR) data analysis have already investigated. By applying the spectral analysis technique Fast Fourier Transform (FFT), the most predominant peak ascillation of rainfall and DMI data has been identified. They are Semi Annual Oscillation (SAO) for Bukit Tinggi, Maninjau, and Sicincin sation, and Annual Oscillation (AO) for Padang-panjang, Padang, Batu Sangkar, Solok, Tabing, Bengkulu, Kotabumi, Jambi, and Palembang station, respectively. While the other predominant peak oscallation in period of 1.5 to 3 years are also found , especially on the DMI data analysis. It indicates that the rainfall variability over these areas could be related to the DM event, especially during DM (+) when the high pressure covers most of Indonesia region. When DM (+) occured, especially on JJA (June-July-August) and SON (September-October-November), the rainfall intensity over those area become less intil below normal condition. Conversely, when DM (-) occured, the amount of rainfall intensity is more than normal condition. Compared to DM (-), DM(+) looks more giving a significant influence to the rainfall in both areas.

HUBUNGAN AIR TERKANDUNG DENGAN REFLEKTIFITAS RADAR Eddy Hermawan; Yuanita Handayati
Jurnal Sains Dirgantara Vol 5, No.1 Desember (2007)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

This paper is mainly concentrated to the correlation between Total Precipitable Water (TPW) on one single column of the vertical air mass and radar reflectivity (Z) over Kototabang (0.2˚S; 100.32˚E), Bukittinggi, West Sumatera based on to the analysis of Radio Acoustic Sounding System (RASS) and Boundary Layer Radar (BLR) data during the Coupling Processes of Equatorial Atmosphere (CPEA) Campaign I from April 10 to May 9, 2004 was going on. wWe firstly reviewed yhe basic concept of TPW using the Weisner method ti estimate the TPW value from the radiosonde data. We reviewed the basic concpt of RASS and BLR system also, especially on the Z data analysis. By arranging the mean value of RASS data every 10 minutes and 150 meter in height, respectively, we estimated the TPW values from the RASS data. By analysing the Cross Cirrelation Function (CCF) of both values taken from SPSS software version 13, we found a good agreement between TPW and Z parameter, especially on 5 May 2004. The correlation values are 0.05, and 0.61 at around 2.7 and 2.25 km, repectively. Although, the maximum correlation value in only 0.61, but this is still good enough to describe the correlation between TPW and Z.

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