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Ketelitian Model Kinematik untuk Memprediksi Karakteristik Longsor (Studi Kasus : Zona Longsor di Ciloto-Puncak, Jawa Barat) Sadarviana, Vera; Z. Abidin, Hasanuddin; Kahar, Joenil; Santoso, Djoko; K, Wedyanto
Indonesian Journal of Geospatial Vol 1, No 1 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (604.185 KB)

Abstract. The geodetic approach based on extraterrestrial survey measurements can be used to study phenomenon, especially to monitoring of material movement characteristic. Landslide is one of prominent catastrophe that continuously affecting in Indonesia, especially in rainy season. In mountainous terrain and areas of steep slope of Indonesia, landslides are frequent, especially where land cover has been removed. Landslides destroy not only environment and property, but usually also cause deaths. Landslide mitigation is therefore very crucial and should be done properly. The velocity and acceleration of several monitored point covering the landslide zone area can be estimated using the geodetic approach. Knowing the relation among these three variables in spatial and temporal domain will be useful for identifying the characteristics of landslide. This information can then be used for better strategy of landslide hazard mitigation. Accuracy of the use of kinematic models for prediction of avalanche characteristics need to be validated so that mitigation will be done correctly. Validation is done by doing a comparison between model predictions and the size of the data and statistical tests for the feasibility of prediction of each point of the GPS monitor. Validation is known that the predicted results at some GPS monitor point is not suitable for use. With the vector of the movement of materials, we know the direction and scalar, velocity and acceleration of material displacement. The movement of landslide materials at Ciloto Zone dominated north-west to south-easterly direction and speed to slow very slow (creep).Â Keywords: accuracy, characteristics, kinematic model, landslide.

Temporal Variation Analysis From Troposphere Delay Using GPS (Study: Bandung, Indonesia) Pradipta, Dhota; Kuntjoro, Wedyanto; Prijatna, Kosasih
Indonesian Journal of Geospatial Vol 1, No 1 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (973.783 KB)

Abstract.Tropospheric delay is the amount of distortion caused by the deceleration of satelliteâs signal propagation due to the influence of troposphere. The value of this delay is certain effect of elevation angle that is called the slant delay. In the processing of GPS signals correction, the value of slant delay will be converted using a mapping function to the measured value of the zenith delay which became known as the Zenith Total Delya (ZTD). Zenith value is an accumulated value of the tropospheric delay along the signalâs path at the zenith direction.Â The value of ZTD can be determined by GPS technique. In Geodesy, ZTD is a nuisance parameter, but for meteorology, it is a parameter of interest, which causes from variability of the atmospheric constituens. The section of ZTD, i.e. Zenith Wet Delay (ZWD), could be derived by substracting Zenith hydrostatic Delay (ZHD) component from ZTD. By surface temperature readings at the GPS receiver, the retrieved ZWD can then be transformed with additional uncertainty into an estimate of the Precipitable Water Vapor (PWV).Â The aim of this research is to study temporal behavior of PWV at ITB campus, as it is revealed from GPS measurements. According to the research that has been conducted, we obtained some results, i.e. The data quality and strategy which were used in processing could affect the result, In particular, we found that, within 20 minutes, maximum and minimum PWV values could reach 85.2 mmand 6.4 mm, respectively. It may indicate that the atmosphere above the studied are varies highly. Temporal condition in observation point that appears in result such as at 12.00 â 18.00 WIB often shows significant irregular anomalies of PWV that influenced local area observation.Â Keywords: GPS, PWV, temporal analysis, ZTD.Â

Determination of ZNHD based on GPS Data, Radiosonde, and Numerical Weather Model Susilo, Susilo; D. Wijaya, Dudy; Kuntjoro, Wedyanto; Efendi, Joni
Indonesian Journal of Geospatial Vol 1, No 2 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2728.084 KB)

Abstract. Water vapor is a principal element in the thermodynamics of the atmosphere and plays an important role in clouds condensation, which eventually can affect the radiative energy balance. Water vapor cobservation is essential for monitoring global/regional scale of weather and climate changes. However, high variation of water vapor concentrations makes it difficult to observe accurately using the conventional meteorogical observation technique (radiosonde), which is limited in both space and time. Nowadays, accurate observation of water vapor can be accomplished by the Global Positioning System (GPS). In this research, we use 14 continuous GPS stations from Bakosurtanal to observe temporal characteristic of water vapor concentration over West Java region.Keywords: GPS, NCEP, radiosonde, topographic, ZNHD

STUDI KONSTANTA TM (MEAN WEIGHT TEMPERATURE) UNTUK PENENTUAN KANDUNGAN UAP AIR DARI DATA GPS DI INDONESIA Susilo, Susilo; Koentjoro, Wedyanto; Efendi, Joni
MAJALAH ILMIAH GLOBE Vol 14, No 2 (2012)
Publisher : Badan Informasi Geospasial

Uap air adalah elemen utama proses termodinamika atmosfer dan mempunyai peranan yang penting dalam proses kondensasi dan pembentukkan awan, yang akhirnya dapat mempengaruhi keseimbangan energi radiasi. Pengamatan uap air sangat penting untuk memantau cuaca dan perubahan iklim dalam skala global/regional. Namun, variasi konsentrasi uap air cukup tinggi sehingga sulit untuk diamati secara akurat dengan menggunakan teknik pengamatan meteorologi konvensional (radiosonde), yang terbatas dalam ruang dan waktu. Saat ini, Global Positioning System (GPS) dapat digunakan untuk pengamatan uap air secara akurat. Penelitian ini, menggunakan data 14 stasiun kontinu GPS Bakosurtanal untuk mengamati karakteristik temporal uap air di atas wilayah Jawa Barat. Delay pengamatan GPS dari setiap stasiun diestimasi dengan interval 1 (satu) jam dalam periode 2008 - 2010. Dengan menggunakan data pengamatan meteorologi di permukaan, delay GPS dikonversi menjadi parameter kandungan uap air (Precipitable Water Vapor/PWV). Konversi dari delay GPS menjadi PWV sangat bergantung dari nilai yang merupakan fungsi dari Tm. Hasil penelitian menunjukkan perbedaan nilai Tm dari radiosonde dan NCEP tidak berpengaruh terhadap nilai , hal ini ditunjukkan dengan nilai rerata bias dari PWV radiosonde dan NCEP terhadap PWV GPS < 1 mm dengan koefisien korelasi > 95%.Kata Kunci: GPS, Kandungan Uap Air, Konstanta TmÂ ABSTRACTWater vapour is a principal element in thermodynamics of atmosphere and plays an important role in clouds condensation, which eventually can affect the radiation energy balance. Water vapor observation is essential for monitoring global/regional scale of weather and climate changes. However, high variation of water vapor concentrations make it difficult to observe accurately using the conventional meteorological observation technique (radiosonde), which is limited in both space and time. Nowadays, accurate observation of water vapor can be accomplished by using Global Positioning System (GPS). This research, used 14 continuous GPS stations from Bakosurtanal to observe temporal characteristic of water vapor concentrations over West Java region. In this research, site-specific zenith tropospheric delays were hourly estimated during three years of GPS measurement period (2008-2010). By using the surface meteorological measurements, those delays were then converted into Precipitable Water Vapour (PWV) parameters. The results show that the value of P did not affected by the variation of Tmas indicated by the mean of the bias of the PWV radiosonde and NCEP to PWV GPS which was less than 1 mm with coefficient of correlation greater than 95%.Keywords: GPS, Precipitable Water Vapor, Tm constant

PENCITRAAN DISTRIBUSI VERTIKAL UAP AIR DI KAWASAN BANDUNG MENGGUNAKAN TEKNIK GPS TOMOGRAFI 1D Sholihah, Suhartawati; Kuntjoro, Wedyanto; Wijaya, Dudy D
Jurnal Meteorologi Klimatologi dan Geofisika Vol 5 No 1 (2018): Jurnal Meteorologi Klimatologi dan Geofisika
Publisher : Unit Penelitian dan Pengabdian Masyarakat Sekolah Tinggi Meteorologi Klimatologi dan Geofisika

Global Positioning System (GPS) tidak hanya berguna untuk keperluan navigasi dan penentuan posisi. GPS juga dapat dimanfaatkan untuk keperluan meteorologi seperti pemantauan kondisi atmosfer Bumi. Sinyal GPS yang ditransmisikan dari satelit ke receiver mengalami perlambatan dan pembelokan akibat adanya partikel-partikel pada lapisan troposfer. Salah satu partikel yang memiliki peranan penting terhadap berlangsungnya siklus hidrologi di Bumi adalah uap air. Uap air tersebut bersifat sangat dinamis baik secara spasial maupun temporal. Perbedaan kandungan uap air pada setiap tempat dan ketinggian menyebabkan besarnya refraktivitas pada lapisan troposfer juga bervariasi. Pemantauan uap air dengan ketelitian tinggi masih menjadi tantangan di Indonesia. Informasi yang akurat mengenai uap air tentunya bermanfaat dalam melakukan prediksi cuaca lokal maupun mempelajari iklim global. Salah satu produk dari pengolahan data GPS adalah informasi mengenai estimasi besarnya bias troposfer pada arah zenith atau disebut sebagai Zenith Tropospheric Delay (ZTD). Besarnya hasil estimasi tersebut kemudian dapat dipisahkan menjadi komponen kering atau Zenith Hydrostatic Delay (ZHD) dan uap air atau Zenith Wet Delay (ZWD). Untuk mengetahui besarnya kandungan uap air pada setiap lintasan sinyal, maka ZWD harus dikonversi menjadi Slant Wet Delay (SWD) dengan mengalikan ZWD dan mapping function. Nilai SWD kemudian digunakan untuk melakukan rekonstruksi distribusi vertikal uap air pada troposfer dengan teknik tomografi. Pada penelitian ini digunakan data pengamatan GPS dari stasiun GPS kontinu (CGPS) ITB  selama satu hari. Hasil yang didapatkan menyatakan bahwa Multiplicative Algebraic Reconstruction Technique (MART) berhasil diterapkan untuk menyelesaikan persamaan linear dalam menentukan refraktivitas komponen basah dengan GPS tomografi 1D. Penelitian lebih lanjut dengan memanfaatkan jaringan stasiun CGPS dan pengembangan metode numerik dapat memberikan hasil yang lebih optimal dan akurat.

Ketelitian Model Kinematik untuk Memprediksi Karakteristik Longsor (Studi Kasus : Zona Longsor di Ciloto-Puncak, Jawa Barat) Vera Sadarviana; Hasanuddin Z. Abidin; Joenil Kahar; Djoko Santoso; Wedyanto K
Indonesian Journal of Geospatial Vol 1 No 1 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract. The geodetic approach based on extraterrestrial survey measurements can be used to study phenomenon, especially to monitoring of material movement characteristic. Landslide is one of prominent catastrophe that continuously affecting in Indonesia, especially in rainy season. In mountainous terrain and areas of steep slope of Indonesia, landslides are frequent, especially where land cover has been removed. Landslides destroy not only environment and property, but usually also cause deaths. Landslide mitigation is therefore very crucial and should be done properly. The velocity and acceleration of several monitored point covering the landslide zone area can be estimated using the geodetic approach. Knowing the relation among these three variables in spatial and temporal domain will be useful for identifying the characteristics of landslide. This information can then be used for better strategy of landslide hazard mitigation. Accuracy of the use of kinematic models for prediction of avalanche characteristics need to be validated so that mitigation will be done correctly. Validation is done by doing a comparison between model predictions and the size of the data and statistical tests for the feasibility of prediction of each point of the GPS monitor. Validation is known that the predicted results at some GPS monitor point is not suitable for use. With the vector of the movement of materials, we know the direction and scalar, velocity and acceleration of material displacement. The movement of landslide materials at Ciloto Zone dominated north-west to south-easterly direction and speed to slow very slow (creep). Keywords: accuracy, characteristics, kinematic model, landslide.

Temporal Variation Analysis From Troposphere Delay Using GPS (Study: Bandung, Indonesia) Dhota Pradipta; Wedyanto Kuntjoro; Kosasih Prijatna
Indonesian Journal of Geospatial Vol 1 No 1 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract.Tropospheric delay is the amount of distortion caused by the deceleration of satellite's signal propagation due to the influence of troposphere. The value of this delay is certain effect of elevation angle that is called the slant delay. In the processing of GPS signals correction, the value of slant delay will be converted using a mapping function to the measured value of the zenith delay which became known as the Zenith Total Delya (ZTD). Zenith value is an accumulated value of the tropospheric delay along the signal's path at the zenith direction. The value of ZTD can be determined by GPS technique. In Geodesy, ZTD is a nuisance parameter, but for meteorology, it is a parameter of interest, which causes from variability of the atmospheric constituens. The section of ZTD, i.e. Zenith Wet Delay (ZWD), could be derived by substracting Zenith hydrostatic Delay (ZHD) component from ZTD. By surface temperature readings at the GPS receiver, the retrieved ZWD can then be transformed with additional uncertainty into an estimate of the Precipitable Water Vapor (PWV). The aim of this research is to study temporal behavior of PWV at ITB campus, as it is revealed from GPS measurements. According to the research that has been conducted, we obtained some results, i.e. The data quality and strategy which were used in processing could affect the result, In particular, we found that, within 20 minutes, maximum and minimum PWV values could reach 85.2 mmand 6.4 mm, respectively. It may indicate that the atmosphere above the studied are varies highly. Temporal condition in observation point that appears in result such as at 12.00 "“ 18.00 WIB often shows significant irregular anomalies of PWV that influenced local area observation. Keywords: GPS, PWV, temporal analysis, ZTD.

Determination of ZNHD based on GPS Data, Radiosonde, and Numerical Weather Model Susilo Susilo; Dudy D. Wijaya; Wedyanto Kuntjoro; Joni Efendi
Indonesian Journal of Geospatial Vol 1 No 2 (2012)
Publisher : Indonesian Journal of Geospatial

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract. Water vapor is a principal element in the thermodynamics of the atmosphere and plays an important role in clouds condensation, which eventually can affect the radiative energy balance. Water vapor cobservation is essential for monitoring global/regional scale of weather and climate changes. However, high variation of water vapor concentrations makes it difficult to observe accurately using the conventional meteorogical observation technique (radiosonde), which is limited in both space and time. Nowadays, accurate observation of water vapor can be accomplished by the Global Positioning System (GPS). In this research, we use 14 continuous GPS stations from Bakosurtanal to observe temporal characteristic of water vapor concentration over West Java region.Keywords: GPS, NCEP, radiosonde, topographic, ZNHD

Pemodelan TEC Regional dari Data GPS Stasiun Tetap di Indonesia dan Sekitarnya Buldan Muslim; Hasanuddin Z. Abidin; The Houw Liong; Wedyanto Kuntjoro; Cecep Subarya; Heri Andreas; M. Gamal
Journal of Mathematical and Fundamental Sciences Vol. 38 No. 2 (2006)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/itbj.sci.2006.38.2.6

Ionosphere affect propagation of electromagnetic waves through it by adding a transmission delay time. In GPS positioning and navigation, ionospheric delay is largest source of error after error from Selective Availability (SA) was turned off. For GPS positioning precisely ionospheric effect must be estimated so ionospheric correction can be determinated to eliminate ionospheric effect on GPS observation. In positioning by using GPS single frequency, ionospheric correction can be obtained from GPS dual frequency receiver at reference station or model. This paper describes method of determination and modeling of regional total electron content (TEC) from continuous GPS station in Indonesia and it's around. Spatial model of TEC at certain time is estimated by using polynomial function. Diurnal variation of polynomial model coefficient at certain hour from 00.00 "“ 23.00 UT is estimated with Fourier expansion.

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