AN ENHANCEMENT TO THE QUANTITATIVE PRECIPITATION ESTIMATION USING RADAR-GAUGE MERGING

Quantitative Precipitation Estimation (QPE) is quite important information for the hydrology fields and has many advantages for many purposes. Its dense spatial and temporal resolution can be combined with the surface observation to enhance the accuracy of the estimation. This paper presents an enhancement to the QPE product from BMKG weather radar network at Surabaya by adjusting the estimation value form radar to the real data observation from rain gauge. A total of 58 rain gauge is used. The Mean Field Bias (MFB) method used to determine the correction factor through the difference between radar estimation and rain gauge observation value. The correction factor obtained at each gauge points are interpolated to the entire radar grid in a multiplicative adjustment. Radar-gauge merging results a significant improvement revealed by the decreasing of mean absolute error (MAE) about 40% and false alarm ratio (FAR) as well an increasing of possibility of detection (POD) more than 50% at any rain categories (light rain, moderate rain, heavy rain, and very heavy rain). This performance improvement is very beneficial for operational used in BMKG and other hydrological needs

IDENTIFIKASI ARAH SEBARAN DAN KETINGGIAN ERUPSI GUNUNG BERAPI MENGGUNAKAN CITRA RADAR CUACA Studi Kasus Erupsi Gunung Agung, 28 Juni 2018 Studi Kasus Erupsi Gunung Agung, 28 Juni 2018: (Identification of Volcanic Ash Propagation and Height Using Weather Radar Imagery, Case study: Mt. Agung Eruption, June 28, 2018)

Erupsi vulkanik pada waktu yang lama dapat membahayakan keselamatan masyarakat dan aktivitas penerbangan. Radar cuaca dapat dimanfaatkan untuk monitoring dan identifikasi sebaran debu vulkanik secara real time. Penelitian ini memanfaatkan radar Gematronik dengan produk yang digunakan antara lain: CMAX, VCUT, dan CAPPI sehingga dapat menganalisis debu vulkanik yang dihasilkan oleh erupsi gunung berapi. Dalam kasus kejadian erupsi Gunung Agung tanggal 28 Juni 2018 didapatkan nilai reflektivitas maksimum mencapai 30-35 dBZ, sedangkan pada produk VCUT didapatkan ketinggian kolom debu vulkanik mencapai 7.5 km. Jenis material erupsi dapat diketahui dengan produk VCUT. Produk CAPPI V yang telah ditentukan batasnya yaitu 3 km, 5 km, dan 7 km menggambarkan arah gerakan debu vulkanik berdasarkan lapisannya. Arah sebaran debu vulkanik dominan ke barat dan barat daya. Dilihat secara horizontal maupun vertikal, debu vulkanik mempunyai karakteristik yang khas yaitu nilai echo reflektivitas menurun seiring menjauhi pusat erupsi.&nbsp

AERONET Remotely Sensed Measurements and Retrievals of Biomass Burning Aerosol Optical Properties During the 2015 Indonesian Burning Season

An extreme biomass burning event occurred in Indonesia from September through October 2015 due to severe drought conditions, partially caused by a major El Niño event, thereby allowing for significant burning of peatland that had been previously drained. This event had the highest sustained aerosol optical depths (AODs) ever monitored by the global Aerosol Robotic Network (AERONET). The newly developed AERONET Version 3 algorithms retain high AOD at the longer wavelengths when associated with high Ångström exponents (AEs), which thereby allowed for measurements of AOD at 675 nm as high as approximately 7, the upper limit of Sun photometry. Measured AEs at the highest monitored AOD levels were subsequently utilized to estimate instantaneous values of AOD at 550 nm in the range of 11 to 13, well beyond the upper measurement limit. Additionally, retrievals of complex refractive indices, size distributions, and single scattering albedos (SSAs) were obtained at much higher AOD levels than possible from almucantar scans due to the ability to perform retrievals at smaller solar zenith angles with new hybrid sky radiance scans. For retrievals made at the highest AOD levels the fine‐mode volume median radii were ~0.25–0.30 micron, which are very large particles for biomass burning. Very high SSA values (~0.975 from 440 to 1,020 nm) are consistent with the domination by smoldering combustion of peat burning. Estimates of the percentage peat contribution to total biomass burning aerosol based on retrieved SSA and laboratory measured peat SSA were ~80–85%, in excellent agreement with independent estimates