Judul: Aerosol Spatial Variation and Its  Relationship with Extreme Rainfall in Indonesia
Abstrak: Curah hujan merupakan salah satu unsur iklim yang terpengaruh oleh perubahan iklim seperti perubahan pola curah hujan, peningkatan intensitas curah hujan, dan peningkatan frekuensi kejadian ekstrem. Salah satu faktor penyebab terjadinya curah hujan adalah aerosol. Aerosol memiliki peran penting dalam iklim global melalui dua mekanisme, yaitu langsung dan tidak langsung. Penelitian ini bertujuan menganalisis korelasi spasial dan pengaruh variasi aerosol terhadap curah hujan di wilayah Indonesia tahun 1990-2019 dan mengetahui tren tahunan aerosol dengan curah hujan ekstrem. Data yang digunakan, yaitu curah hujan bulanan dan harian CHIRPS, serta data reanalisis aerosol black carbon, organic carbon, dan sulfat MERRA-2 tahun 1990-2019. Terdapat 4 indeks curah hujan ekstrem yang digunakan dari ETCCDMI (Expert Team for Climate Change Detection Monitoring and Indices), yaitu RX5day (max 5-day precipitation amount), R95P (very wet days), R10mm (number of heavy precipitation days), dan CWD (consecutive wet days). Hasil penelitian menunjukkan distribusi korelasi signifikan antara aerosol dengan curah hujan dengan tingkat kepercayaan 80% terdapat di semua pulau di Indonesia dengan nilai korelasi maksimum 0,6 dan -0,6. Distribusi korelasi tertinggi terdapat di pulau Papua dan terendah di pulau Jawa, hal ini dikarenakan terdapat banyak faktor penyebab curah hujan. Tren tahunan curah hujan ekstrem dengan aerosol di Pulau Papua dan Pulau Jawa menunjukkan tren positif yaitu seiring bertambahnya tahun, nilai aerosol mengalami peningkatan yang diikuti peningkatan fluktuasi indeks curah hujan ekstrem yang menunjukkan kenaikan nilai aerosol menyebabkan kenaikan fluktuasi curah hujan ekstrem di kedua Pulau tersebut dengan nilai aerosol Pulau Jawa yang lebih tinggi dibandingkan Pulau Papua., Rainfall is one of the climate elements that is affected by climate change, such as changes in rainfall patterns, increased rainfall intensity, and increased frequency of extreme events. One of the factors causing rainfall is aerosols. Aerosols have an essential role in the global climate through two mechanisms, namely, direct and indirect. This study aims to analyze the spatial correlation and the effect of aerosol variations on rainfall in the Indonesian region from 1990-2019 and determine the annual trend of aerosols with extreme rainfall. The data used are CHIRPS monthly and daily rainfall, MERRA-2 black carbon, organic carbon, and sulfate aerosol reanalysis data for 1990-2019. There are four extreme rainfall indices used from ETCCDMI (Expert Team for Climate Change Detection Monitoring and Indices), namely RX5day (max 5-day precipitation amount), R95P (very wet days), R10mm (number of heavy precipitation days), and CWD (consecutive wet days). The results showed the distribution of a significant correlation between aerosols and rainfall, with a confidence level of 80% found in all Indonesian islands with a maximum correlation value of 0.6 and -0.6. The highest correlation distribution is on the island of Papua and the lowest is on the island of Java. This is because many factors cause rainfall. The annual trend of extreme rainfall with aerosols on the Papua and Java Islands shows a positive trend. That means as the years increased, the aerosol value increased, followed by an increase in extreme rainfall index fluctuations. This shows that an increase in aerosol value causes an increase in extreme rainfall fluctuations on the two islands, with a value of aerosols on
Keyword: Aerosol, extreme rainfall, Jawa island, Papua island, spatial  correlation

Judul: Spatial Analysis of Aerosol Optical Depth (AOD) Based on Precipitation and Wind Variation Over Western Region of Java
Abstrak: Kualitas udara di wilayah Jawa Bagian Barat dipengaruhi secara dinamis melalui perubahan lingkungan akibat tingginya aktivitas antropogenik. Aerosol sebagai partikulat padat yang mempengaruhi kualitas udara, cuaca, dan iklim, dapat diestimasi melalui parameter Aerosol Optical Depth (AOD) yang menggambarkan beban aerosol dalam kolom atmosfer. Penelitian ini menganalisis karakteristik spasial AOD dan mengeksplorasi keterkaitan curah hujan dan pola angin terhadap distribusi AOD pada musim basah dan musim kering melalui analisis regresi spasial. Hasil penelitian menunjukkan secara statistik, besar kelajuan angin tidak berpengaruh signifikan terhadap nilai AOD. Namun, arah angin terlihat mempunyai pengaruh terhadap distribusi curah hujan dan AOD yang terkait dengan sistem monsun. Analisis regresi spasial pada musim hujan (periode DJF-MAM) menunjukkan bahwa curah hujan tidak berpengaruh signifikan terhadap AOD (p-value > 0,05). Kurangnya pengaruh yang signifikan pada musim hujan disebabkan oleh tingginya intensitas dan curah hujan menyebar luas, yang secara efektif menghilangkan aerosol dari atmosfer. Sebaliknya, saat musim kering terdapat pengaruh signifikan curah hujan terhadap distribusi spasial AOD (p-value < 0,05). Distribusi spasial AOD dapat dijelaskan oleh pola spasial curah hujan dengan R² sebesar 32% pada model Ordinary Least Squares (OLS) dan 84% pada model Spatial Lag Model (SLM). Secara keseluruhan, penelitian ini menekankan interaksi kompleks antara faktor meteorologi dan aerosol dalam konteks musiman yang berbeda., Air quality in the Western Region of Java Island is dynamically influenced by environmental changes resulting from anthropogenic activities. Aerosols, as solid particulates that affect air quality, weather, and climate, can be estimated using the parameter Aerosol Optical Depth (AOD), which represents the aerosol load in the atmospheric column. This study analyzes the spatial characteristics of AOD and explores the influence of rainfall and wind patterns on the AOD distribution based on wet and dry season through spatial regression analysis. The research results show that statistically, wind speed has no significance on the AOD value. However, the wind direction appears to have an influence on the distribution of precipitation and AOD associated with the monsoon system. Spatial regression analysis in the wet season (DJF-MAM period) shows that precipitation does not significantly influence AOD (p-value > 0.05). The significant lack of influence in wet season is due to the high intensity and widespread nature of precipitation, which effectively scavenges aerosols from the atmosphere. In contrast, during the dry season, precipitation significantly influences the spatial pattern of AOD (p-value < 0.05). The spatial distribution of AOD can be explained by the spatial pattern of precipitation with an R² of 32% in the Ordinary Least Squares (OLS) model and 84% in the Spatial Lag Model (SLM). Overall, this research highlight the complex interplay between meteorological factors and aerosol in different seasonal context.
Keyword: precipitation, spatial regression, AOD, wind pattern

Judul: Construction of Strongly Optimal Binary Linear Code with Minimum Distance 9 and 11
Abstrak: A binary linear code of length n over q F is a subspace of n q F . A code has three parameters that attached to it, namely length, dimension, and minimum distance. A code with length n, dimension k and minimum distance d is often called [n, k, d ]-code. Usually, when two parameters are given, then we want to find a code that has the best value for the last parameter. Based on Gilbert- Varshamov bound, if a [n, k, d ]-code exists and can not be expanded, we call it a strongly optimal code. In this paper, we construct strongly optimal code with minimum distance 9 and 11. In constructing the code, we created a theorem and algorithm based on Gilbert-Varshamov bound before we implement the algorithm to MAPLE programming language. Because of computational limitations, the program can only construct up to k = 10 for d = 9 and k = 12 for d = 11.
Keyword: