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VARIASI SPASIAL DAN TEMPORAL HUJAN KONVEKTIF DI PULAU JAWA BERDASARKAN CITRA SATELIT(SPATIAL AND TEMPORAL VARIATION OF CONVECTIVE RAIN IN JAVA ISLAND BASED ON CITRA IMAGES) Kusumawati, Yetti; Effendy, Sobri; Aldrian, Edvin
Jurnal Agromet Indonesia Vol 22, No 1 (2008): June 2008
Publisher : PERHIMPI (Indonesian Association of Agricultural Meteorology)

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Abstract

Convective rain is one of precipitation types that usually occur in Indonesia, result by convective process. This convective rain brings heavy rainfall in short period and could reach a higher intensity than common monsoon rain. Convective process may have a variation with time and location. This research have determined spatial and temporal variation of convective rain in Java island by using the black body temperature (TBB) gradient method based on the GMS-6 (MTSAT-1R) images. As a result, the seasonal convective rain generally occurred in similar period i.e. in the morning from 07.00 to 11.00 LT (local time) and in the evening from 18.00 LT until 05.00 LT. The maximum event occurred from 18.00 LT until mid night. There were different locations between the seasonal convective event. In the seasonal convective rain, there were two spatial patterns. In wet season (DJF) and transitional season from wet to dry (MAM) convective rain spread from east to west Java. While in dry season (JJA) and transitional season from dry to wet (SON), convective rain mostly occurred only in west Java.
Long Term Rainfall Trend of The Brantas Catchment Area, East Java Aldrian, Edvin; Djamil, Yudha Setiawan
Indonesian Journal of Geography Vol 38, No 1 (2006): Indonesian Journal of Geography
Publisher : Faculty of Geography, Universitas Gadjah Mada

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Spatial and temporal rainfall analyses of the Brantas Catchment Area from 1955 to 2002 based on 40 daily rainfall stations has been performed. To identify the climate pattern for the last five decades, we used the Empirical Orthogonal Function (EOF) followed by the Fast Fourier Transform. By using EOF, we found the monsoonal pattern as the most dominant, which explains about 72% of all variances. The interannual pattern shows a negative trend of the monsoonal strength. From the monthly isohyets for each decade, the rainfall amount appears to decrease significantly during the last five decades, indicated by wider low rainfall amount areas and the orographic effect is detected, indicated by always greater amount in highlands. From rainfall data in mountain and coastal areas, dry periods had been increasing, mainly in lowlands. Thus, the continued imbalance of the dry and wet period is one cause of the monsoonal strength decrease during the last five decades.
SPATIOTEMPORAL CHARACTERISTICS OF EXTREME RAINFALL EVENTS OVER JAVA ISLAND, INDONESIA ., Supari; ., Sudibyakto; Ettema, Janneke; Aldrian, Edvin
Indonesian Journal of Geography Vol 44, No 1 (2012): Indonesian Journal of Geography
Publisher : Faculty of Geography, Universitas Gadjah Mada

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Abstract

The patterns and trends of extreme daily rainfall within period of 1981 – 2010 have beenanalyzed for Java Island, Indonesia particularly East Java Province. A set of extreme indicesrecommended by WMO were calculated using high quality data from 84 rain stations toexpress the frequency and intensity of those events. The spatial patterns was identified bymapping climatological mean of indices while temporal trends was assessed using the nonparametricMann-Kendal test. The study found that the spatial pattern of extreme rainfallevents over East Java Province is generally characterized by low frequency and intensity inthe coastal area, and high frequency and intensity in the mountainous area. The dominantfinding from trend assessment is not-significant trend. However, the consistently significanttrend was observed in some districts. Rain stations in District of Ponorogo, Ngawi,Bojonegoro, Gresik and Sumenep showed significant negative trend for almost all indiceswhereas significant positive trend was found in District of Surabaya and Pasuruan.
Ocean-atmosphere analysis of Super Typhoon Songda 2011 over Western North Pacific Ocean Ilhamsyah, Yopi; Bey, Ahmad; Aldrian, Edvin; Affan, Junaidi M.
Proceedings of The Annual International Conference, Syiah Kuala University - Life Sciences & Engineering Chapter Vol 3, No 3 (2013): Addendum
Publisher : Syiah Kuala University

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Abstract

The purpose of the research is to understand the influences of ocean and atmosphere to the formation of Super Typhoon Songda 2011. Daily SST from NOAA AVHRR with spatial resolution of 0.5° in latitude and longitude was used to study upper oceanic response to the formation of Typhoon Songda. Meanwhile, 3-hourly meteorological data from ARP model with spatial coverage of 0.5° Latitude x 0.5° Longitude cover 201 x 101 points from 25° N - 20° S and 70.0° E – 170.0° E as well as 13 levels of atmospheric columns was also used in the study. The study was also supported by  MT-SAT satellite images. The result showed that from early disturbances until reaching mature stage of Typhoon Songda, SST over WNP reached averages temperature of 30˚C. Warm ocean waters continuously produce heat and moisture to the air that are necessary to fuel the genesis, development, formation and intensification of Typhoon Songda. The study also proved that light vertical wind shear (850 – 200 hPa) at about 0 – 5 knot was observed in the early development of Songda at 1800 UTC on May 19th. For the time being, weak vertical wind shear extended to the northwestern of Pacific Ocean. Thus, it made the system to moved toward northwest and reached category Super Typhoon few days later on May 26th. The study also showed the present of Monsoon trough. Monsoon trough occurred where easterly wind met the reversal southerly wind. The region was stretched from southeast to northwest part of WNP Ocean and designated by an extended low pressure area at the surface as well as extended bands of thunderstorms as observed by satellite imagery. On the other hand, potential vorticity shown in the present paper is useful to obtain an understanding of atmospheric motions and development of the upper-level disturbance. Potential vorticity maximum characterize strong vorticity and upward motion. Conversely, weak vorticity with downward motion is demonstrated by mininum potential vorticity.
ANALISIS PEMBANGUNAN RENDAH KARBON STUDI KASUS PROPINSI LAMPUNG Adi, Seno; aldrian, edvin; nuraini, dian; saroja, damayanti; tejakusuma, iwan G
Jurnal Sains dan Teknologi Indonesia Vol 13, No 2 (2011)
Publisher : Jurnal Sains dan Teknologi Indonesia

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Abstract

The increasing trend of CO2 emission globally, has been creating climate change in some areas in the world. The impact of climate change could cause disaster for human life such as drought and flood, health deseases, etc. Currently many programs and schemes are introduced to reduce CO2 emission. The low carbon development is one of those programs which is the economic development has to take into acount the CO2 emission reduction. This study found 90 % of the CO2 emision came from forestry sector, especially deforestation and fires. The recent CO2 emission was 70,3 MtCO2e in 2005 and estimated 79 MtCO2e in 2020, then finally will be 93,5 MtCO2e. Therefore mitigation actions should be focused on the forestry sector, these are reforestation & afforestation, REDD, mangrove rehabilitation, agroforestry development, and fire protection. These action programs potentially could reduce the CO2 emission as high as 76,8% in 2030.
AN INDICATION OF SEA-AIR INTERACTION THAT AFFECTS THE CLIMATE PATTERN OVER THE MOLUCCAN SEA Aldrian, Edvin
Jurnal Sains & Teknologi Modifikasi Cuaca Vol 3, No 2 (2002): December 2002
Publisher : BPPT

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Abstract

Starting with the regional annual cycle of rainfall over Molucca, which follow the sun eclipse movement instead of the common Inter Tropical Convergence Zone (ITCZ) movement, a suspicion of the sea-air interaction driven climate pattern comes up. The empirical study on rainfall – sea surface temperature (SST) relationship clarifies a function of rainfall accumulation to SST. A strong evident on the interaction comes from the result of Ocean General Circulation Model (OGCM). The model shows a surface water intrusion that comes from west Pacific into the north Molucca Sea before it enter the mainstream of the Indonesian throughflow in the north end of the Makasar strait. Most of the throughflow, as shown by the model, come from north Pacific, enter the Makasar strait southward and go into the Indian ocean through the Lombok strait (mostly) and a strait between Flores and Timor island. The intrusion of surface water in north Molucca conserves the warm sea surface temperature and keep a high convective area.Diawali dengan pembagian region berdasarkan pola hujan tahunan di Maluku, yangmengikuti pergerakan tahunan matahari dan bukannya yang biasa yaitu Inter TropicalConvergence Zone (ITCZ), kecurigaan akan adanya interaksi laut udara yang mendorong pola iklim timbul. Studi empiris mengenai hubungan hujan dan suhu permukaan laut menjelaskan fungsi akumulasi hujan terhadap suhu laut. Indikasi kuat adanya interaksi berasal dari keluaran model global sirkulasi laut. Model menunjukkan adanya intrusi arus permukaan dari pasifik barat ke Maluku utara sebelum masuk ke alur utama dari arus lintas Indonesia di ujung utara selat makasar. Sebagian besar arus lintas, sebagaimana dituntukkan oleh model, berasal dari utara, memasuki selat Makasar ke selatan dan menuju ke samudra Indonesia kebanyakan melalui selat Lombok dan sebagian kecil melalui selat antara pulau Flores dan Timor. Intrusi arus permukaan di utara Maluku menjaga kehangatan suhu muka laut dan menjaga daerah konvektif aktif.
PEMBAGIAN IKLIM INDONESIA BERDASARKAN POLA CURAH HUJAN DENGAN METODA “DOUBLE CORRELATION” Aldrian, Edvin
Jurnal Sains & Teknologi Modifikasi Cuaca Vol 2, No 1 (2001): June 2001
Publisher : BPPT

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Abstract

Pembagian wilayah atau region iklim Indonesia berdasarkan pola curah hujan tahunandibahas disini. Sebuah metoda yang dinamakan metoda “double correlation” diperkenalkan untuk tujuan di atas. Dengan metoda regionalisasi yang dipakai dihasilkan tiga region iklim berdasarkan pola curah hujan tahunan. Region pertama adalah region A yang terletak di wilayah selatan Indonesia yang disebut region monsun Australia karena region ini lebih banyak dipengaruhi oleh monsun Australia. Region kedua adalah region B di wilayah barat laut Indonesia, yang disebut sebagai region monsun passat tenggara karena dipengaruhi oleh monsun ini. Region terakhir adalah region C atau region arus lintas laut Indonesia (arlindo) karena terletak pada daerah aliran arlindo. Pola hasil dari regionalisasi ini dibandingkan dengan pola pada region yang sama pada keluaran model reanalisa ECMWF dan ECHAM.A regionalization of Indonesian climate based on its annual rainfall patterns has been done. A new method called the “double correlation method” was introduced and used for such purpose. With this regionalization method there are three climate regions based on their annual rainfall patterns. The first region or region A lies in south Indonesia and is called the Australian monsoon region because it is much affected by the Australian monsoon. The second region or region B lies in northwest Indonesia, which is called as the NE Passat region because it is much affected by that monsoon. The last region or region C lies over the Indonesian Throughflow and is called as the Indonesian Throughflow region. Patterns resulted from this regionalization method are compared to those of their corresponding regions from the output of ECMWF reanalysis and a Global Circulation Model ECHAM.
THE SIMULATION OF CO- AND CROSS-POLAR CHARACTERS OF RAINFALL DROPLETS AND CHAFF Aldrian, Edvin
Jurnal Sains & Teknologi Modifikasi Cuaca Vol 3, No 2 (2002): December 2002
Publisher : BPPT

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Abstract

The error analyses and simulations of the co- and cross-polar characters of chaff andrainfall have been done. Error analyses include the ZDR distribution, numbers ofscaterers, the orientation and shape dependence, the system DC bias, the channel gainimbalance and the quantification errors. There is no effect of number of scatterers on the noise. The orientation and shape dependence study indicates wider frequency distribution of ZDR from chaff is because of the chaffs needle shape. The orientation of chaff contributes insignificantly to noises The noises has been reduced considerably after eliminating system DC bias and gaining more channel balance. Further possible source of error is the quantification error in data analyses. LDR is more useful than ZDR when both chaff and rain are present. The result suggests a possibility of using chaff’s LDR in tracing air movement.Analisa error dan simulasi sifat co- dan cross-polar dari chaff dan butir -butir hujan telahdilakukan. Analisa error termasuk penyebaran ZDR, jumlah chaff atau bidang pemantul(scatterers), orientasi dan bentuk dari chaff, factor kesalahan DC, keseimbangan keduakanal pada radar dan factor kesalahan kuantitatif unit. Tidak ada sumbangan kesalahandari jumlah scatterers pada noise. Penelitian orientasi dan bentuk menunjukkan lebarnya penyebaran ZDR pada chaff karena bentuknya. Orientasi dari chaff tidak menyumbang factor kesalahan yang berarti. Noise telah dapat dikurangi hingga minimal setelah menghilangkan factor kesalahan system DC dan menyeimbangkan kedua kanal. Faktor kesalahan lainnya yang mungkin adalah kesalahan kuantitatif unit pada analisis data. LDR lebih berguna dari ZDR ketika kedua duanya yaitu chaff dan butir hujan berada. Hasil tersebut menyarankan kegunaan chaff LDR untuk pemantauan pergerakan udara.
THE SPECTRUM THRESHOLD FILTER METHOD FOR CHAFF AND RAIN Aldrian, Edvin
Jurnal Sains & Teknologi Modifikasi Cuaca Vol 3, No 1 (2002): June 2002
Publisher : BPPT

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Abstract

Polarization doppler radar observations of chaff and rain were conducted. At least in thevertical pointing case, the spectrum of chaff is much narrower than that of rain. In dataanalysis a new method of filtering chaff data from noise is used. This filter method, named the spectrum threshold filter method, was also applied for rain data for comparison. Instead of using the average power as in the conventional method this fil ter method utilizes the doppler spectral peak power. Consequently this filter method is able to detect a presence of even a single strong doppler velocity signals. Hence the performance of this filter is better with metallic strips, such as chaff, than raindrops. The variation of the filter’ s threshold will change significantly the filtered rainfall area but not the chaff one. The filter technique is also useful to detect a narrow but strong spectral data.Pengamatan hujan dan chaff dengan memakai radar dengan polarisasi doppler telahdilakukan. Paling tidak pada posisi tegak lurus, spektrum dari chaff lebih sempit daripada pada butir hujan. Dalam melakukan analisa data kita telah mengembangkan sebuah metoda filtering untuk memilah data chaff dari noise sekitarnya. Metoda filter ini, yang disebut metoda filter spectrum threshold, juga diterapkan pada data hujan sebagai perbandingan. Daripada memakai kekuatan rata-rata dengan metoda umumnya, metoda filter ini memakai puncak spektrum. Sehingga metoda filter ini dapat mendeteksi keberadaan dari hanya sebuah puncak kecepatan doppler dalam sinyal. Pada akhirnya kinerja metoda filter ini lebih baik untuk aplikasi pada pita-pita logam seperti chaff daripada butiran hujan. Variasi dari batas ambang (threshold) dari filter ini akan mengubah area hujan yang terfilter secara drastis tetapi tidak pada data chaff. Teknik filter ini juga berguna untuk mendeteksi spektrum doppler yang sempit tetapi kuat.
POLA HUJAN RATA-RATA BULANAN WILAYAH INDONESIA; TINJAUAN HASIL KONTUR DATA PENAKAR DENGAN RESOLUSI ECHAM T -42 Aldrian, Edvin
Jurnal Sains & Teknologi Modifikasi Cuaca Vol 1, No 2 (2000): December 2000
Publisher : BPPT

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Abstract

Kajian temporal dari sifat iklim Indonesia berdasarkan pola curah hujan rata-rata bulanan telah dilakukan dengan mengacu pada beberapa parameter ECMWF seperti angin 850 mb, OLR dan suhu permukaan. Parameter ECMWF tersebut dapat menjelaskan hampir semua pola kecuali daerah yang terdapat pola gangguan lokal. Dengan kajian temporal ini, penulis menemukan ITCZ, daerah siklon di utara Australia dan aktivitas monsun yang dominan pada beberapa bulan. Hasil lainnya menunjukkan adanya perioda transisi pada bulan April dan Oktober yang dapat dimengerti dari pola angin 850 mb dan suhu permukaan. Juga dijelaskan bahwa puncak hujan tahunan di Bali ke Timor lebih banyak dipengaruhi oleh siklon tropis di utara Australia daripada monsun Asia.Temporal assesment of Indonesian climate characteristic based on monthly rainfall pattern was done with several ECMWF (European Center for Medium Range Weather Forecast) parameters; i.e. wind field of 850 mb, Outgoing Longwave Radiation (OLR) and surface temperature. Those ECMWF parameters could explain almost all rainfall pattern with some exceptional areas which are due to their local disturbances. With this temporal assesment, the author found Inter Tropical Continental Zone (ITCZ), cyclonic area in north of Australia and monsoon activities which are dominant in some specific months. One results of this research shows transitional period existence in April and October which are fully understood by analysis of 850 mb wind and surface temperature. It is also explained that peak of rainfall pattern in Bali - Timor area are much characterized by tropical cyclones in north of Australia rather than by Asian monsoon.