Judul: Characteristic of Overshooting Top (OT) Based on  Himawari  8  Satellite  as  a  Convective  Cloud  Feature  that  Generates  Extreme Weather in the Java Island Region
Abstrak: Overshooting Top (OT) is a feature at the top of a convective cloud that is associated with extreme weather. Research on OT in tropical Indonesia is still very limited. The existence of geostationary satellites with wide area coverage and fast frequency observations is useful for observing the fast dynamics of the OT life cycle. Therefore, this study intends to analyze the relationship between OT and extreme weather, updraft and thermodynamic conditions of OT when extreme weather occurs, the best objective method for detecting OT in the day time and night time, and the spatiotemporal distribution of OT in the tropical region of Java Island during the 2018-2021 period. Based on visual analysis using visible channel and Himawari 8 sandwich products, 87% of extreme weather events in Java were accompanied by the appearance of OT. It indicates that the presence of the OT pattern is a convection cloud pattern or feature that is closely related to extreme weather events for the Java Island region. The existence of a time lag between the appearance of OT and extreme weather events on Java Island indicates that the OT of convection cloud can be used as a precursor or nowcasting for the appearance of extreme weather. Most of the convective cloud OT features during extreme weather events on Java Island have altitude that were only able to exceed the altitude of the equilibrium level and few were able to exceed the tropopause level of 9 km – 16 km. The difference in atmospheric conditions during extreme weather events on Java Island, which is in the tropics and subtropics, is a strong and unstable convective energy condition characterized by a larger CAPE, as well as unstable KI, LI, SI and TTI values. It is offset by kinematic factors in the form of a weak vertical wind shear (bulk wind shear 0-6 km) and a higher freezing point height. The difference between extreme weather events in the Java Island region and other tropical regions compared to subtropical regions is the strong updraft speed of convection clouds. The IRW Texture COMB algorithm based on the IRW-Texture Gradient modification and the COMB algorithm shows a significant increase in quality for detecting OT and non-OT pixels in Java. Rainy days with rainfall > 50 mm/day are very common in areas with an altitude of > 500 m. On the other hand, the level of convection activity which is indicated by the presence of OT and lightning is significantly reduced in this area. OT of convective clouds appear more frequently during the DJF season and less frequently during the JJA season. OT often appears during the day time and rarely at night time. Most OTs appear in the central part, away from the south and north coasts of Java Island during the day, while OTs that appear near the south and north coasts of Java Island can appear in the morning or afternoon.
Keyword: convective clouds, extreme weather, Overshooting Tops, Himawari 8 Satellite

Judul: Identification of Cross-Equatorial Northerly Surge and Indian Ocean Dipole Phenomenon in Rain Events in West Part of Java
Abstrak: Aliran massa udara yang berasal dari Laut Cina Selatan (LCS) melewati equator dan merambah ke Laut Jawa dan Pulau Jawa bagian Barat dapat menyebabkan peningkatan curah hujan yang dilewatinya, aliran tersebut dapat disebut Cross Equatorial Northerly Surge (CENS). Fenomena CENS bukan satu-satunya penyebab peningkatan atau penurunan curah hujan di Pulau Jawa. Indian Ocean Dipole (IOD) juga dapat menyebabkan perubahan curah hujan di Pulau Jawa. Penelitian ini bertujuan untuk menganalisis pola curah hujan selama kejadian CENS, IOD, dan secara bersamaan. Data yang digunakan pada penelitian ini yaitu data curah hujan lima stasiun pengamatan serta data angin permukaan, Suhu Permukaan Laut (SPL), anomali SPL dan transport kelembaban. Hasil penelitian menunjukkan bahwa peningkatan pola curah hujan yang tinggi di empat stasiun pengamatan selama CENS pada tahun 2004-05, kecuali di Stasiun Geofisika Cemara Bandung. Sementara selama CENS dengan IOD negatif pada tahun 2004 05, peningkatan pola curah hujan terjadi di Stasiun Klimatologi Dramaga Bogor, Meteorologi Kemayoran, dan Meteorologi Kertajati. CENS dengan IOD positif pada tahun 2019 menyebabkan rendahnya curah hujan di lima stasiun pengamatan dibandingkan selama kejadian CENS dan CENS dengan IOD negatif. Meskipun demikian, peran signifikan CENS dalam membawa massa udara lembab dapat mengakibatkan hujan., The airflow originating from the South China Sea (LCS) crosses the equator and extends to the Java Sea and Western Java Island, potentially causing increased rainfall along its path. This flow is referred to as the Cross-Equatorial Northerly Surge (CENS). However, the CENS phenomenon is not the sole factor influencing rainfall variability on Java Island. The Indian Ocean Dipole (IOD) also contributes to changes in rainfall patterns on Java. This study aims to analyze rainfall patterns during occurrences of CENS, IOD, and their combined effects. The data used in this research includes rainfall data from five observation stations, as well as surface wind data, Sea Surface Temperature (SST), SST anomalies, and moisture transport. The results show significant increases in rainfall patterns at four observation stations during CENS in 2004-05, except at the Geophysics Station Cemara Bandung. Meanwhile, during CENS with negative IOD in 2004-05, increased rainfall patterns were observed at the Climatology Station Dramaga Bogor, Meteorology Kemayoran, and Meteorology Kertajati. CENS with positive IOD in 2019 resulted in lower rainfall across the five observation stations compared to the periods of CENS and CENS with negative IOD. Nevertheless, the significant role of CENS in transporting moist air can lead to rainfall.
Keyword: CENS, IOD, Moisture Transport, Rainfall, SST

Judul: Proses fermentasi Fed-Batch untuk produksi dekstranase dari isolat bakteri Streptococcus sp. B7
Abstrak: Penelitian ini bertujuan untuk mengembangkan teknik fermentasi pada produksi enzim dekstranase dari isolat bakteri Streptococcus sp B7 dengan mempergunakan sistem fermentasi fed-batch. Fermentasi fed-batch produksi dekstranase dilakukan pada fermentor kapasitas 2 liter dengan laju penambahan substrat 19 ml/jam dengan waktu fermentasi 3 kali 24 jam. Perlakuan yang dilakukan pada penelitian ini adalah pH dan kecepatan putaran. Perlakuan pH dilakukan pada pH 7 dan pH 8, sedangkan kecepatan putaran yang digunakan adalah 300 dan 500 rpm. Aktivitas relatif tertinggi dari semua perlakuan dicapai pada fermentasi dengan kecepatan putaran 500 rpm pada pH 8 yang mencapai 920 U/ml. Hasil terbaik ditinjau dari parameter kinetik terten- tu adalah sebagai berikut: produksi 920 U/ml, produktivi- tas 16.43 U/ml/jam, aktivitas spesifik 17.78 U/mg pro- tein, Yp/x 696.97 U/g sel dan produktivitas spesifik 12.45 U/g sel/jam.
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