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EFEK PARAMETERISASI LAPISAN BATAS ATMOSFER TERHADAP PEMBENTUKAN GELOMBANG GRAVITAS DI SUMATERA BARAT [THE EFFECT OF ATMOSPHERIC BOUNDARY LAYER PARAMETERIZATION TO THE GENERATION OF GRAVITY WAVES OVER WEST SUMATERA] Dyah Ayu Putriningrum; Nurjanna Joko Trilaksono; - Noersomadi
Jurnal Sains Dirgantara Vol 12, No 1 (2014)
Publisher : Lembaga Penerbangan dan Antariksa Nasional

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1148.083 KB)

Gelombang gravitas berperan dalam sirkulasi dinamika atmosfer dan mempengaruhi proses-proses di Lapisan Batas Atmosfer (LBA). Gelombang gravitas telah diidentifikasi dengan simulasi temperatur potensial dan kecepatan angin menggunakan model Weather Research and Forecasting–Advance Research WRF (WRF-ARW) dengan kondisi inisial dan kondisi batas model dari data final analyses (FNL) tanggal 16–17 Maret 2008. Simulasi dilakukan dalam tiga domain nested (bersarang) dengan resolusi horizontal paling tinggi sebesar 3 km. Metode simulasi dilakukan dengan membandingkan dua skema parameterisasi LBA yang berbeda yakni Medium Range Forecast (MRF) dan Yonsei University (YSU). Metode analisis menggunakan transformasi Fourier dan wavelet. Dari hasil simulasi, gelombang gravitas berhasil diidentifikasi dengan baik menggunakan skema MRF di atas Sumatera Barat saat aktivitas konveksi sedang terjadi dengan nilai Cloud Water Mixing Ratio (CWMR) sekitar 0,1-2,1 g/kg. Ciri-ciri gelombang gravitas yang terdeteksi merupakan gelombang gravitas berperiode singkat (~2 jam) dengan panjang gelombang horizontalnya 5–50 km. Perbedaan karakter gelombang gravitas yang dihasilkan simulasi, berhubungan dengan sensitivitas skema parameterisasi LBA dan resolusi grid horizontal. Gelombang gravitas dapat disimulasikan oleh skema MRF dengan resolusi horizontal 3 km yang dapat menghasilkan panjang gelombang yang lebih pendek.Kata kunci: Gelombang gravitas, Lapisan Batas Atmosfer, WRF-ARW, Parameterisasi

KAITAN EFEK BLOCKING PEGUNUNGAN TENGAH PAPUA BAGIAN SELATAN DENGAN DISTRIBUSI PRESIPITASI Dian Mayangwulan; Nurjanna Joko Trilaksono
Jurnal Meteorologi dan Geofisika Vol 20, No 1 (2019)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Pegunungan tengah Papua yang membentang lebih dari 500 km dengan ketinggian diatas 2000 m, khususnya wilayah kaki pegunungan bagian selatan menerima presipitasi tinggi, terutama pada periode musim dingin Australia (Mei-September). Penelitian ini membahas: a) variasi tahunan efek blocking ditinjau dari nilai Froude number (Fr) pada periode Januari 2000 – Desember 2014, dan b) variasi harian moisture flux convergence (MFC) pada studi kasus simulasi menggunakan model skala-meso Weather Research and Forecasting – Enviromental Modeling System (WRF-EMS) untuk periode Juli 2008, dan pengaruhnya terhadap presipitasi di wilayah tersebut. Metode singular value decomposition (SVD) digunakan untuk mengetahui hubungan spasial-temporal Fr dengan presipitasi, sedangkan hubungan variasi harian Fr dan MFC hasil simulasi terhadap variasi presipitasi menggunakan analisis cross-correlation. Analisis Fr selama periode penelitian menunjukkan aliran selalu terbendung, dan pola SVD mode pertama menunjukkan aliran dari tenggara sefase dengan distribusi spasial presipitasi di selatan pegunungan namun memiliki korelasi lemah (≤0,4). Simulasi dilakukan pada bulan Juli 2008 saat kecepatan angin meridional mencapai maksimum untuk mengetahui variasi MFC dan kaitannya dengan presipitasi pada wilayah kajian. Analisis cross-correlation antara presipitasi dan MFC menunjukkan korelasi maksimum (0,52) terjadi pada lag +6jam. MFC relatif lebih kuat hubungannnya terhadap curah hujan maksimum harian dibanding dengan Fr. Hari kering pada area selatan pegunungan (

Turbulence analysis on the flight of Etihad airways in Bangka Island using the WRF case study May 4, 2016 Bayu Retna Tri Andari; Nurjanna Joko Trilaksono; Muhammad Arif Munandar
Jurnal Meteorologi dan Geofisika Vol 23, No 3 (2022): Special Issue
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v23i3.912

Accurate weather forecasts should support the increase in safety of aviation operations in Indonesia. This weather forecast is needed, especially in detecting turbulence, considering that geographically Indonesia has effective solar radiation resulting in convective cloud formation. Convective clouds can trigger turbulence then produce disruption and even accidents on flights. This research uses a case study on the Etihad Airways flight on Bangka Island on May 4, 2016. At the time of the incident, there was turbulence at 39,000 feet altitude, and the aircraft did not enter the cloudy area. The Weather Research and Forecasting (WRF) model is used to simulate the turbulence in this study, which is downscaled up to 3 km with a microphysics parameterization of WRF Single Moment 6 Class (WSM6). The results were then verified using correlation and linear regression for temperature, wind direction, wind speed, and pattern resemblance between cloud fraction and the convective nuclei distribution. The turbulence is analyzed from the south-north and west-east vertical airflow. The turbulence spotted at 06.40 UTC when there is a quite strong updraft which can cause turbulence. The turbulence parameters used, such as the eddy dissipation rate (EDR) parameter, which has a value of 0.05 , Richardson number with a value of less than 0.25, and turbulence index (TI 1) with a maximum value of 4 x 10-7 s-2 found that turbulence was in a strong category. The turbulence that occurs in this study is identified as near cloud turbulence (NCT) event due to cloud formation observed in the west of the turbulence and intense updraft activity at the location of turbulence.

Generating himawari-8 time series data for meteorological application Ahmad Luthfi Hadiyanto; Ketut Wikantika; Ary Setijadi Prihatmanto; Nurjanna Joko Trilaksono; Dedi Irawadi
Indonesian Journal of Electrical Engineering and Computer Science Vol 29, No 2: February 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v29.i2.pp780-787

Optical remote sensing images have been widely used for temporal monitoring. The data is acquired by sensors on satellites with better spatial resolution compared to in-situ measurements by meteorological stations. The problem with utilizing optical images is the cloud, which blocks the ground and near-ground information collected by satellites. To overcome this problem, especially when dealing with thermal bands, we propose a procedure including aggregation and spatial interpolation methods to obtain time series data over a region. There is still no reference to selecting the data period to calculate the aggregate value and apply spatial interpolation. An assessment is proposed by applying Yamane’s formula in the time domain and thresholding the number of pixels in the spatial domain. Himawari-8 data was utilized and collected on an hourly basis over Java Island. This algorithm is applied to a sequence of periodic datasets to obtain a time series of aggregate data for meteorological applications. The result of this study is a recommendation to use three-month periods of data over the eastern part of Java.

PEMISAHAN AWAN KONVEKTIF DAN STRATIFORM DALAM MENGKAJI SIKLUS DIURNAL DAN MIGRASINYA DI PEGUNUNGAN BAWAKARAENG SULAWESI SELATAN BERDASARKAN DATA RADAR CUACA Syamsul Bahri; Nurjanna Joko Trilaksono
Jurnal Meteorologi dan Geofisika Vol 20, No 2 (2019)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v20i2.424

Aktivitas konvektif diurnal merupakan mode paling dominan di Benua Maritim Indonesia (BMI). Namun kajian yang telah dilakukan sebelumnya tidak memisahkan periode analisis berdasarkan musim sekaligus pemisahan awan konvektif dan stratiform. Selain itu, data yang digunakan terbatas baik resolusi temporal maupun horizontalnya. Adapun tujuan dari kajian ini untuk mengetahui siklus dan migrasi diurnal awan konvektif dan stratiform pada musim berbeda. Kajian migrasi sistem awan hujan dilakukan dengan menggunakan radar cuaca C-Band polarisasi tunggal yang berlokasi di Maros (4.997733o LS, 119.572014o BT) dan terletak pada bagian barat Pegunungan Bawakaraeng (PB) Sulawesi Selatan. Metode Steiner dkk., digunakan untuk mengklasifikasikan awan hujan menjadi dua yaitu awan konvektif dan stratiform. Pada bulan Desember-Januri-Februari (DJF) terdapat aktifitas awan hujan yang bermigrasi secara zonal (timur-barat) yaitu awan konvektif di laut yang bergerak ke darat mulai pagi hari hingga siang dan awan stratiform di darat (gunung) bergerak menuju laut. Selain itu awan hujan juga tampak bermigrasi secara meridional (utara-selatan) yang didominasi oleh awan konvektif. Hasil analisis temporal siklus diurnal menunjukkan bahwa awan stratiform terjadi setelah satu jam puncak awan konvektif. Pada bulan Maret-April-Mei (MAM) aktifitas awan konvektif hanya terdapat di darat (gunung) dan tidak tampak adanya migrasi, berbeda halnya dengan awan stratiform yang tampak bermigrasi ke laut yang sangat jelas terlihat pada wilayah PB bagian utara. Adapun siklus diurnal awan konvektif di pesisir dan gunung maksimum terjadi pada sore hari berbeda dengan awan stratiform yang terjadi dua kali yaitu pada sore hari dan awal pagi. Puncak siklus awan stratiform terjadi setelah dua jam puncak awan konvektif

PEMISAHAN AWAN KONVEKTIF DAN STRATIFORM DALAM MENGKAJI SIKLUS DIURNAL DAN MIGRASINYA DI PEGUNUNGAN BAWAKARAENG SULAWESI SELATAN BERDASARKAN DATA RADAR CUACA Syamsul Bahri; Nurjanna Joko Trilaksono
Jurnal Meteorologi dan Geofisika Vol. 20 No. 2 (2019)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v20i2.424

Aktivitas konvektif diurnal merupakan mode paling dominan di Benua Maritim Indonesia (BMI). Namun kajian yang telah dilakukan sebelumnya tidak memisahkan periode analisis berdasarkan musim sekaligus pemisahan awan konvektif dan stratiform. Selain itu, data yang digunakan terbatas baik resolusi temporal maupun horizontalnya. Adapun tujuan dari kajian ini untuk mengetahui siklus dan migrasi diurnal awan konvektif dan stratiform pada musim berbeda. Kajian migrasi sistem awan hujan dilakukan dengan menggunakan radar cuaca C-Band polarisasi tunggal yang berlokasi di Maros (4.997733o LS, 119.572014o BT) dan terletak pada bagian barat Pegunungan Bawakaraeng (PB) Sulawesi Selatan. Metode Steiner dkk., digunakan untuk mengklasifikasikan awan hujan menjadi dua yaitu awan konvektif dan stratiform. Pada bulan Desember-Januri-Februari (DJF) terdapat aktifitas awan hujan yang bermigrasi secara zonal (timur-barat) yaitu awan konvektif di laut yang bergerak ke darat mulai pagi hari hingga siang dan awan stratiform di darat (gunung) bergerak menuju laut. Selain itu awan hujan juga tampak bermigrasi secara meridional (utara-selatan) yang didominasi oleh awan konvektif. Hasil analisis temporal siklus diurnal menunjukkan bahwa awan stratiform terjadi setelah satu jam puncak awan konvektif. Pada bulan Maret-April-Mei (MAM) aktifitas awan konvektif hanya terdapat di darat (gunung) dan tidak tampak adanya migrasi, berbeda halnya dengan awan stratiform yang tampak bermigrasi ke laut yang sangat jelas terlihat pada wilayah PB bagian utara. Adapun siklus diurnal awan konvektif di pesisir dan gunung maksimum terjadi pada sore hari berbeda dengan awan stratiform yang terjadi dua kali yaitu pada sore hari dan awal pagi. Puncak siklus awan stratiform terjadi setelah dua jam puncak awan konvektif

KAITAN EFEK BLOCKING PEGUNUNGAN TENGAH PAPUA BAGIAN SELATAN DENGAN DISTRIBUSI PRESIPITASI Dian Mayangwulan; Nurjanna Joko Trilaksono
Jurnal Meteorologi dan Geofisika Vol. 20 No. 1 (2019)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v20i1.431

Pegunungan tengah Papua yang membentang lebih dari 500 km dengan ketinggian diatas 2000 m, khususnya wilayah kaki pegunungan bagian selatan menerima presipitasi tinggi, terutama pada periode musim dingin Australia (Mei-September). Penelitian ini membahas: a) variasi tahunan efek blocking ditinjau dari nilai Froude number (Fr) pada periode Januari 2000 – Desember 2014, dan b) variasi harian moisture flux convergence (MFC) pada studi kasus simulasi menggunakan model skala-meso Weather Research and Forecasting – Enviromental Modeling System (WRF-EMS) untuk periode Juli 2008, dan pengaruhnya terhadap presipitasi di wilayah tersebut. Metode singular value decomposition (SVD) digunakan untuk mengetahui hubungan spasial-temporal Fr dengan presipitasi, sedangkan hubungan variasi harian Fr dan MFC hasil simulasi terhadap variasi presipitasi menggunakan analisis cross-correlation. Analisis Fr selama periode penelitian menunjukkan aliran selalu terbendung, dan pola SVD mode pertama menunjukkan aliran dari tenggara sefase dengan distribusi spasial presipitasi di selatan pegunungan namun memiliki korelasi lemah (≤0,4). Simulasi dilakukan pada bulan Juli 2008 saat kecepatan angin meridional mencapai maksimum untuk mengetahui variasi MFC dan kaitannya dengan presipitasi pada wilayah kajian. Analisis cross-correlation antara presipitasi dan MFC menunjukkan korelasi maksimum (0,52) terjadi pada lag +6jam. MFC relatif lebih kuat hubungannnya terhadap curah hujan maksimum harian dibanding dengan Fr. Hari kering pada area selatan pegunungan (

Turbulence analysis on the flight of Etihad airways in Bangka Island using the WRF case study May 4, 2016 Bayu Retna Tri Andari; Nurjanna Joko Trilaksono; Muhammad Arif Munandar
Jurnal Meteorologi dan Geofisika Vol. 23 No. 3 (2022): Special Issue
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v23i3.912

Accurate weather forecasts should support the increase in safety of aviation operations in Indonesia. This weather forecast is needed, especially in detecting turbulence, considering that geographically Indonesia has effective solar radiation resulting in convective cloud formation. Convective clouds can trigger turbulence then produce disruption and even accidents on flights. This research uses a case study on the Etihad Airways flight on Bangka Island on May 4, 2016. At the time of the incident, there was turbulence at 39,000 feet altitude, and the aircraft did not enter the cloudy area. The Weather Research and Forecasting (WRF) model is used to simulate the turbulence in this study, which is downscaled up to 3 km with a microphysics parameterization of WRF Single Moment 6 Class (WSM6). The results were then verified using correlation and linear regression for temperature, wind direction, wind speed, and pattern resemblance between cloud fraction and the convective nuclei distribution. The turbulence is analyzed from the south-north and west-east vertical airflow. The turbulence spotted at 06.40 UTC when there is a quite strong updraft which can cause turbulence. The turbulence parameters used, such as the eddy dissipation rate (EDR) parameter, which has a value of 0.05 , Richardson number with a value of less than 0.25, and turbulence index (TI 1) with a maximum value of 4 x 10-7 s-2 found that turbulence was in a strong category. The turbulence that occurs in this study is identified as near cloud turbulence (NCT) event due to cloud formation observed in the west of the turbulence and intense updraft activity at the location of turbulence.

Propagation Characteristics of Madden Julian Oscillation in the Indonesian Maritime Continent: Case Studies for 2020-2022 Istiqomah, Fadhilatul; Yulihastin, Erma; Wiratmo, Joko; Hermawan, Eddy; Trilaksono, Nurjanna Joko; Irawan, Dasapta Erwin; Yohanes, Kristy Natasha; Ayunina, Amalia Qurrotu
Agromet Vol. 38 No. 1 (2024): JUNE 2024
Publisher : PERHIMPI (Indonesian Association of Agricultural Meteorology)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29244/j.agromet.38.1.1-12

Madden-Julian Oscillation (MJO) can affect weather and climate variability in the Indonesian Maritime Continent. MJO propagation is not always the same, previous research has classified MJO into 4 categories: slow, fast, stand, and jump. The objective of this study is to investigate the differences in MJO propagation and the factors that impact it. Daily data for variables such as Outgoing Longwave Radiation (OLR), zonal wind, and sea surface temperature are utilized in this research. The collected data is processed using composite methods based on the 8 MJO phases, with a specific focus on the years 2020, 2021, and 2022. The research findings suggest that warm sea surface temperatures in the Pacific Ocean and zonal winds dominated by Kelvin waves are favorable for MJO propagation. Conversely, cooling sea surface temperatures in the Pacific Ocean and zonal winds dominated by equatorial Rossby waves can hinder MJO propagation. Future researchers are expected to examine the impact of MJO propagation during extreme rainfall occurrences in several regions of Indonesia, as well as the application of machine learning and deep learning methods to predict MJO propagation in the future.

Improving Short-Term Weather Forecasting using Support Vector Machine Method in North Barito Wulandari, Ayu Vista; Trilaksono, Nurjanna Joko; Ryan, Muhammad
Jurnal Meteorologi dan Geofisika Vol. 25 No. 2 (2024)
Publisher : Pusat Penelitian dan Pengembangan BMKG

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31172/jmg.v25i2.1096

Flooding is a recurring issue in North Barito Regency due to the overflow of the Barito River. Weather forecasts in the region rely mainly on Numerical Weather Prediction (NWP) models, which often fail to capture local details due to their grid-based homogenization. To address this limitation, statistical techniques such as Model Output Statistics (MOS) can enhance NWP outputs by representing local conditions more accurately . MOS establishes statistical relationships between response variables (predictands) and predictor variables derived from NWP outputs, enabling operational applications without the need for advanced instruments. This study utilizes rainfall data from 2021-2022 from the Beringin Meteorological Station in North Barito as the response variable, while data from the Integrating Forecasting System (IFS) model serve as the predictor variables. The Support Vector Machine (SVM) method is employed to identify the relationship between predictor and response variables. By integrating the MOS technique with the SVM method, this research aims to improve the accuracy of weather forecasting, particularly for short-term predictions in North Barito. This approach demonstrates the potential to enhance localized weather predictions by addressing the limitations of conventional NWP models. The results indicate a consistent reduction in RMSE across all experiments conducted. Furthermore, the SVM model showed notable improvements in bias values and exhibited a stronger correlation compared to the original outputs from the IFS model. The percentage improvement (%IM) in rainfall forecasts, following correction using the SVM model, increased by 5.03%. The percentage improvement (%IM) in rainfall forecasts, following correction using the SVM model, increased by 5.03% for use as a predictor variable in the applied SVM method. In contrast, a combination of surface pressure, temperature across various layers, and rainfall proved to be the the most effective input variables for enhancing the accuracy of weather forecasting in North Barito using the SVM model.

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