EVALUASI SKEMA PARAMETERISASI MODEL WRF UNTUK PENGAMATAN KEMUNCULAN AWAN DARI SATELIT HIMAWARI-8 DI ATAS INDONESIA

Berbagai kombinasi skema parameterisasi kumulus dan mikrofisika telah diimplementasikan pada model WRF untuk menemukan skema terbaik kemunculan awan saat siang hari di atas Indonesia. Parameterisasi dilakukan dengan melakukan simulasi model ensemble resolusi tinggi selama sebulan menggunakan delapan skema kumulus dan empat skema mikrofisika. Selanjutnya hasil simulasi dibandingkan dengan data awan yang diturunkan satelit Himawari-8 pada tiga level ketinggian. Hasil perbandingan menunjukkan bahwa kombinasi skema kumulus Kain-Fritsch dan skema tanpa kumulus/eksplisit, serta skema mikrofisika WSM3 menghasilkan korelasi yang cukup tinggi untuk kemunculan awan berdasarkan perhitungan nilai skill (score skill) dan analisa spasial. Secara umum, korelasi kemunculan awan luaran WRF dan Himawari-8 lebih baik pada awan tinggi daripada awan menengah atau rendah, dan hasil model cenderung overestimate di semua level ketinggian

Measurement and characterization of infrasound waves from the March 25, 2023 thunderstorm at the near equatorial

Thunderstorm activity on March 25, 2023 provided a unique opportunity to study the mechanism of lightning events on changes in air pressure. In particular, this event made it possible to study changes in air pressure during thunderstorms using various instruments. This paper presented comprehensive results of infrasound, satellite data, weather radar and weather measurements at the ground during the storm. Observations of lightning events were confirmed using observational data from the International Space Station's Lightning Imaging Sensor (ISS LIS). This work estimated three spectral percentile values on infrasonic sensor data, time series interpolation of standard meteorology profiles, weather radar reflectivity and total radiant energy of lightning from ISS LIS observations during the day and night periods. As a result, during the investigation, it was seen that the recorded infrasound signal in the 0.6–0.8 Hertz (Hz) range was contaminated by background environmental noise, but in the 1–3 Hz band range it was consistent with the appearance of storms that produce high energy blows. Infrasound detection and electromagnetic lightning detection show good correlation up to a distance of 100 km from the infrasonic station. During a thunderstorm, the ISS LIS flight directly above the observation site detected more than 2,000 lightning events. In addition, the application of lightning detection from several independent instruments can provide a complete picture of the observed event

Detection of Equatorial Atmospheric Wave Signal on COSMIC-GPS Radio Occulation Data Using Empirical Orthogonal Function

Hal. 23-2

PENENTUAN ONSET MONSUN DI WILAYAH INDO-AUSTRALIA BERDASARKAN LOMPATAN ITCZ

Inter-Tropical Convergence Zone (ITCZ) is one of the factors affecting weather and climate in the Indonesia Maritime-Continent Region together with El-Niño Southern Oscillation (ENSO), Indian Ocean Dipole Mode (IODM), Madden Julian Oscillation (MJO), Tropical Cyclone (TC), and Monsoon. ITCZ influence weather and climate in the Indonesia region. Therefore, monitoring and understanding ITCZ behaviour become important as an alternative method to predict variability, anomaly, and extreme atmospheric conditions in Indonesia region. Research has been conducted to study the behaviour of ITCZ in the Indonesia maritime-continent region using Multi-Functional Transport Satellite (MTSAT) data from year 2006 to 2009. Identification of ITCZ and its movement was carried out based on minimum cloud top temperature observed by MTSAT satellite. Meridional movement of ITCZ were then compared to the Indo-Australia Monsoon Indices and rainfall from Tropical Rainfall Measuring Mission (TRMM) satellite. The results showed that ITCZ positions tend to exist at certain locations and experienced jumps to mid-latitude during seasonal change to dry and wet seasons. The results can be used to predict monsoon onset in the Indo-Australia region based on ITCZ jumps, and also to verify rainfall prediction models which in turn can be applied to hydrological models, environtmental models, and rainfall-related disaster early warning systems. Keywords: ITCZ, Monsoon, Onset, Satellite, Indonesi

PENENTUAN ONSET MONSUN DI WILAYAH INDO-AUSTRALIA BERDASARKAN LOMPATAN ITCZ

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Konsistensi Angin Zonal Terhadap Posisi ITCZ Untuk Menentukan Onset Monsun

Consistency of zonal pattern to the ITCZ over southern Indonesia Maritim Continent (IMC) (2-10oS, 105-150oE) have investigated using NCEP/NCAR Reanalysis data of NOAA Satellite and MTSAT Satellite data from 2008 to 2011. Results described zonal wind over 850 milibar consist to ITCZ position based on minimum temperature black body of MTSAT Satellite cloud cover. Strong westerly was identified while ITCZ on nothern equator. On the other hand, strong easterly was identified while ITCZ on southern equator. While ITCZ jump from northern (southern) equator to southern (northern), zonal wind also migrate from easterly (westerly) to westerly (easterly). Hereafter, the times periode could be used to identify onset monsoon date over southern IMC. Zonal wind characteristic for explaine monsoon onset date should have significant intensity (>3 m.s) and persistent (> 10-day). Synoptic scale disturbance in Pacific Ocean influence to zonal wind stability in transition season periods. La Nina phase relate to intensify westerly over southern IMC, such as occured on transition season (from rainy to dry) of 2008 and 2011. On the contrary, El Nino influence to minimize easterly so that westerly tend to persist, such as on 2010 of transition season periods.Hal. 80-8

Interaction Between Cens-Mjo Transition Phase Affect To Diurnal Anomaly Of The Rainfall Over West Java

Cross-Equatorial Northerly Surge (CENS) mostly occurs in wet season period over West Java with the effect of developing convective activity and increase rainfall over northern West Java. Madden Julian Oscillation (MJO) in a transition period from the wet to the dry phase that affects probably the decrease of cloud cluster from Indian Ocean to West Java. The interaction between the CENS and Madden Julian Oscillation (MJO) in the transition phase was researched using 3 hourly rainfall of TRMM Satellite 3B42 for 10 years, from 2002 to 2013. The results of the average of 11 events showed that daily rainfall was concentrated over Java Sea in the morning until late afternoon. In the afternoon, high rainfall seemed to be identified in the southeastern part of West Java. In addition, rainfall anomaly data illustrates that in the early morning (01-04 LT), anomaliesof positive rainfall occured over the northern land and negative anomalies was over the Java Sea. Conversely, during noon (13-16 LT), the positive anomalies occured over the Java Sea while negative anomalies occured over the land. At night, the maximum positive anomalies occur over almost all parts of West Java.Hal. 14-2

The ITCZ Characteristics Based On MTSAT Satellite

This research presents profile of the Intertropical Convergence Zone (ITCZ) based on MTSAT Satellite dataset from 2004 to 2009. The dataset uses both of visible and infrared channels (IR1) to observe global cloud covers (50oN-50oS, 70oE-150oW) with 0.25 of spatial degrees resolution and GPCP precipitation data. The ITCZ profile in January showed that ITCZ line existed on equator. Over Indonesia Maritime Continent, ITCZ line across over southern Sumatera, southern Kalimantan, and southern Sulawesi. However, in July, the ITCZ appeared in northern equator and did not across over Indonesia Maritime Continent (around Malaysia Peninsula). In April and October, the ITCZ line persistent in near equator and across over Indonesia Maritime Continent. Over Pacific Ocean, the ITCZ occurred clearly except second of 10-daily in April. Furthermore,time series profile of the ITCZ explained that line of the ITCZ jumped from 7o S to 3o N in the first 10-daily of April which confirmed to monsoon onset of dry season in southern Indonesia Maritime Continent (Indo-Australia). It was also occurred in the first 10-daily of December which consistent to rainy season.Hal. 144-14

Monthly Rainfall Characteristics In Indonesia In Connection With The Meridional Movement Of Intertropical Convergence Zone

Hal. 103-11