Judul: Analysis Evapotranspiration In The Wet Tropic: South Lampung and North Jakarta In 1998-2017
Abstrak: Analisis Evapotranspirasi di Daerah Tropika Basah: Lampung Selatan dan Jakarta Utara Tahun 1998-2017. Evapotranspirasi (ETo) merupakan gabungan dari proses evaporasi dari permukaan tanah dan tanaman, serta proses transpirasi melalui kanopi tanaman. Evapotranspirasi merupakan komponen penting dalam memengaruhi keseimbangan hidrologi di suatu wilayah, karena nilainya menduduki porsi fase air yang cukup besar. Penelitian ini bertujuan untuk mendapatkan gambaran perubahan nilai evapotranspirasi selama 20 tahun di Jakarta Utara dan Lampung Selatan. Metode penelitian ini dilakukan dengan menggunakan analisis tren iklim historis dan evapotranspirasi. Nilai evapotranspirasi diperoleh dengan menggunakan metode Penman-MonteithMetode ini merupakan metode paling baik untuk menghitung nilai evapotranspirasi. Hal tersebut dikarenakan nilai korelasi (r) dari hasil penghitungan evapotranspirasi metode Penman-Monteith dengan pengukuran menggunakan lisimeter lebih dari 97 % untuk seluruh bulan. Selain itu, nilai standard error dari metode ini juga menunjukkan angka terkecil yakni 32 % dibanding dengan metode lain.. Evapotranspirasi tahunan di Lampung Selatan dan Jakarta Utara menunjukkan garis tren naik dalam 20 tahun terakhir, dengan kemiringan garis tren yang lebih besar di wilayah Jakarta Utara dibandingkan dengan di wilayah Lampung Selatan. Dalam kurun waktu 20 tahun nilai evapotranspirasi pada periode musiman di wilayah Lampung Selatan dan Jakarta Utara memiliki nilai evapotranspirasi tertinggi pada periode SON (September-Oktober-November) dan nilai terendah ada pada periode JJA (Juni-Juli-Agustus)., Analysis of Evapotranspiration in Wet Tropics: South Lampung and North Jakarta 1998-2017. Evapotranspiration (ETo) is a combination of the evaporation process from the soil surface and plants, as well as the transpiration process through the plant canopy. Evapotranspiration is an important component in influencing the hydrological balance in an area, because its value occupies a fairly large portion of the water phase. This study aims to obtain an overview of changes in the value of evapotranspiration for 20 years in North Jakarta and South Lampung. This research method is carried out using historical climate trend analysis and evapotranspiration. The evapotranspiration value was obtained using the Penman-Monteith method. This method is the best method for calculating the evapotranspiration value. This is because the correlation value (r) from the calculation of evapotranspiration using the Penman-Monteith method with measurements using a lysimeter is more than 97% for the entire month. In addition, the standard error value of this method also shows the smallest number, which is 32% compared to other methods. Annual evapotranspiration in South Lampung and North Jakarta shows an upward trend line in the last 20 years, with a greater slope of the trend line in the North Jakarta area. compared to the South Lampung region. In a period of 20 years, the evapotranspiration value in the seasonal period in South Lampung and North Jakarta has the highest evapotranspiration value in the SON period (September-October-November) and the lowest value is in the JJA period (June-July-August).
Keyword: ETo, evapotranspiration, South Lampung, North Jakarta, temperature, trend

Judul: Analysis of 144 Years of Rainfall and Air Temperature Conditions and their Association with Climate Variability in Central Jakarta
Abstrak: Penelitian ini bertujuan mengidentifikasi perubahan tren suhu udara dan pola curah hujan, serta mengkaji pengaruh variabilitas iklim terhadap fluktuasi curah hujan dan suhu udara di wilayah Jakarta Pusat selama 144 tahun (1876-2019). Data ini dianalisis menggunakan metode analisis tren, analisis distribusi probabilitas, analisis spektral, dan korelasi curah hujan dan suhu udara dengan indeks El-Nino Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), dan Pacific Decadal Oscillation (PDO). Curah hujan, suhu minimum, suhu rata-rata, dan suhu maksimum mengalami kenaikan dengan laju kenaikan masing-masing sebesar 1,7747 mm/tahun, 0,0161oC/tahun atau 2,4oC, 0,0179oC/tahun atau 2,6oC, dan 0,0208oC/tahun atau 3,0oC selama 144 tahun. Analisis spektral menunjukkan bahwa variabilitas tertinggi curah hujan musim panas berada pada periode 17 bulan, sedangkan musim dingin berada pada periode 22 bulan. Suhu rata-rata dan suhu maksimum musim panas variabilitas tertinggi berada pada periode 83 bulan, sedangkan musim dingin, pada periode 31 bulan dan 83 bulan. ENSO dan curah hujan berkorelasi positif, sedangkan ENSO dan suhu udara berkorelasi negatif. IOD dan curah hujan berkorelasi positif hanya pada musim dingin, sedangkan IOD dengan suhu udara berkorelasi positif pada setiap musim. PDO tidak memiliki hubungan signifikan dengan curah hujan dan suhu udara hampir pada setiap musimnya. Penelitian ini menunjukkan bahwa terjadi peningkatan tren curah hujan dan suhu udara selama 144 tahun (1876-2019)., This study aims to identify changes in air temperature trends and rainfall patterns, and to examine the influence of climate variability on fluctuations in rainfall and air temperature in the Central Jakarta area for 144 years (1876-2019). This data was analyzed using the methods of trend analysis, probability distribution analysis, spectral analysis, and correlation in rainfall and air temperature with the El-Nino Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), and Pacific Decadal Oscillation (PDO) indices. Rainfall, minimum temperature, average temperature, and maximum temperature increased with an increased rate of 1,7747 mm/year, 0,0161oC/year or 2,4oC, 0,0179oC/year or 2,6oC, and 0,0208oC/year or 3,0oC over 144 years, respectively. Spectral analysis shows that the highest variability of summer rainfall is in the 17 months period, while winter is in the 22 months period. The highest variability of summer mean and maximum temperatures are in the 83 months, while the winter is in the 31-month and 83-month periods. ENSO and rainfall are positively correlated, while ENSO and air temperature are negatively correlated. IOD and rainfall are positively correlated only in winter, while IOD and air temperature are positively correlated every season. PDO has no significant relationship with rainfall and air temperature almost every season. This study shows an increasing precipitation and air temperature trend over 144 years (1876-2019).
Keyword: Air Temperature, ENSO, IOD, PDO, Rainfall

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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