National Institute for Environmental Studies (NIES) has been implementing a joint monitoring project of greenhouse gases (GHGs) and air pollutants in Indonesia with Bogor Agricultural University (IPB), Agency for the Assessment and Application of Technology (BPPT), and Meteorological, Climatological, and Geophysical Agency (BMKG). To estimate the amount of anthropogenic emissions from Jakarta megacity (Jabodetabek) and compare with city activities, we developed a ground-based comprehensive monitoring system of GHGs and air pollutants and installed it at Bogor (center of Bogor city) in March 2016, Serpong (Jakarta suburb) in August 2016, and Cibeureum (mountainous area, background-like site) in March 2017. The monitoring system consists of data acquisition/control units and the instruments for continuous measurements of CO2, CH4, CO, NOx, SO2, O3, aerosol concentrations (PM2.5, PM10, BC) and the chemical components, and meteorological parameters. Flask sampling of air is also done to analyze N2O, SF6, and carbon isotopes (13C, 14C) in CO2 and to validate the continuous measurement data. The result shows that CO2 mole fractions observed at three sites have clear diurnal variations representing the minimum values from 12 to 15 local time while the values at Bogor and Serpong are 6.8 and 7.1 ppm higher than Cibeureum, respectively.

Sugarcane productivity is naturally affected by climate variables and limited by the water availability. This study simulated a water balance model to estimate sugarcane water requirement and to estimate the best planting time as well based on its optimum productivity in Kediri Regency. Water requirement was estimated by water loss of evapotranspiration following FAO No. 24, while the productivity was based on mid-maturing sugarcane growth and development. Sugarcane rainfed area in Kediri Regency needs approximately 26-128 mm water per month based on its loss by evapotranspiration. The value varied due to the growth phase. More than 60% water was used in vegetative phase for developing buds and stem elongation of about 3-9 months after planting. The highest sugarcane productivity was obtained in July-September as the best planting time shown by simulation. Moreover, water deficiency during mid-season of sugarcane growth could decrease productivity by a significant amount. The work presented here could be used as a tool to help decision makers for irrigation management and select the best planting date.

Penelitian ini bertujuan untuk mendapatkan profil cuaca serta semua komponen yang mempengaruhi neraca energi selama periode kering musim tanam II yang terjadi di areal persawahan Kabupaten Indramayu, dilaksanakan bulan Juni hingga September 2012. Hasil penelitian menunjukkan fluktuasi cuaca harian dan parameter Nisbah Bowen umumnya mengikuti penerimaan radiasi neto sesuai karakter masing-masing seperti suhu, gradien suhu bola kering, kecepatan angin, limpahan bahang tanah dan limpahan bahang laten yang meningkat selama siang hari dan menurun kembali menjelang sore hari. Sebaliknya, gradien suhu bola basah, kelembaban dan tekanan udara, menurun selama siang hari dan kembali meningkat menjelang sore hari. Rata-rata harian unsur cuaca dan parameter bowen antara lain radiasi neto 241 W m-2, suhu udara 28,3 oC, kelembaban relatif 66%, tekanan udara 101 kPa, limpahan bahang tanah 8,1 W m-2, nisbah bowen 0,16, limpahan bahang laten 172,9 W m-2. Radiasi neto yang diterima permukaan selama penelitian relatif konstan antara 183 W m-2 sampai 268 W m-2 dengan rata-rata 231 W m-2, suhu udara rata-rata 29,4 oC. Kelembaban relatif berkisar antara 45% hingga 67% dengan rata-rata 59%, sedangkan tekanan udara rata-rata 101 kPa. Angin bertiup lebih banyak ke arah tenggara (138,4 o) dengan kecepatan rata-rata 0,9 m s-1. Limpahan bahang tanah berkisar antara 4,7 W m-2 sampai 14,6 W m-2 dengan rata-rata 7,9 W m-2 sedangkan Nisbah Bowen berkisar antara 0,02 sampai 0,22 dengan rata-rata 0.10. Limpahan bahang laten berbanding lurus terhadap penerimaan radiasi neto dengan nilai berkisar antara 134,4 W m-2 sampai 226,5 W m-2 dengan rata-rata 184 W m-2. ©2017 dipublikasikan oleh Savana Cendana.

Penelitian ini bertujuan untuk menduga nilai evapotranspirasi dengan metode Nisbah Bowen di lahan sawah. Studi kasus di Kabupaten Indramayu, dilaksanakan bulan Juni hingga September 2012. Komponen cuaca yang diukur dengan sistem Nisbah Bowen adalah radiasi neto, suhu bola basah dan bola kering, gradien suhu bola basah dan bola kering pada ketinggian antara 140 cm dan 160 cm serta pada ketinggian antara 160 cm dan 180 cm dan limpahan bahang tanah. Pengukuran setiap 30 menit mulai pukul 06.00 sampai pukul 18.00 Komponen yang diukur dengan AWS adalah radiasi, suhu, kelembaban, tekanan udara, curah hujan, arah dan kecepatan angin. Perhitungan dengan metode Nisbah Bowen kemudian dibandingkan dengan perhitungan menggunakan metode FAO Penman-Monteith. Hubungan evapotranspirasi harian hasil perhitungan dengan dua metode tersebut dianalisis dengan Korelasi (Pearson Correlation). Hasil penelitian menunjukkan evapotranspirasi harian di areal persawahan Kabupaten Indramayu pada saat periode kekeringan musim tanam II yang diduga menggunakan metode Nisbah Bowen berkisar antara antara 2,4 mm sampai 4,3 mm dengan rata-rata 3,3 mm, sedangkan evapotranspirasi harian yang diduga menggunakan metode FAO Penman-Monteith bervariasi antara 2,4 mm sampai 4,6 mm dengan rata-rata 3,5 mm. Rata-rata hasil estimasi evapotranspirasi harian dari kedua metode secara statistik tidak berbeda nyata. ©2017 dipublikasikan oleh Savana Cendana.

<p>Solar radiation greatly affects the development of plant biomass. The process of plant development is complex. Here, we simplified this complexity through modeling experiment by integrating climate variables. This study aims to determine the dynamics of canopy intercepted solar radiation under soybean (<em>Glycine Max (L.) Merrill</em>). We employed the shierary-rice model to calculate plant biomass. The results showed that intercepted radiation continuosly increased during vegetative phase, whereas the radiation remains constant during generative phase. Our observation confirmed that the pattern of intercepted radiation followed the angular pattern of sunlight. The intercepted radiation was optimum at 10:00 to 14:00 pm, and it was used to form the plant dry matter. We found that the intercepted radiation contributed until 12%. Based on this contribution, we built our crop model of soybean biomass. Our model performed well in simulating dry biomass with high R² (0.9), and as indicated by the plot 1:1 between dry matter of model and field observations. Further, the result of t test between model and observed data confirm this strong corelation (<em>p-value</em> 0.07).</p>