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Báo cáo hóa học: " Short range tracking of rainy clouds by multiimage flow processing of X-band radar data"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Short range tracking of rainy clouds by multiimage flow processing of X-band radar data | Mesin EURASIP Journal on Advances in Signal Processing 2011 2011 67 http asp.eurasipjournals.eom content 2011 1 67 o EURASIP Journal on Advances in Signal Processing a SpringerOpen Journal RESEARCH Open Access Short range tracking of rainy clouds by multiimage flow processing of X-band radar data Luca Mesin Abstract Two innovative algorithms for motion tracking and monitoring of rainy clouds from radar images are proposed. The methods are generalizations of classical optical flow techniques including a production term modelling formation growth or depletion of clouds in the model to be fit to the data. Multiple images are processed and different smoothness constraints are introduced. When applied to simulated maps including additive noise up to 10 dB of SNR showing formation and propagation of objects with different directions and velocities the algorithms identified correctly the production and the flow and were stable to noise when the number of images was sufficiently high about 10 . The average error was about 0.06 pixels px per sampling interval AT in identifying the modulus of the flow velocities between 0.25 and 2 px AT were simulated and about 1 in detecting its direction varying between 0 and 90 . An example of application to X-band radar rainfall rate images detected during a stratiform rainfall is shown. Different directions of the flow were detected when investigating short 10 min or long time ranges 8 h in line with the chaotic behaviour of the weather condition. The algorithms can be applied to investigate the local stability of meteorological conditions with potential future applications in nowcasting. Keywords X-band radar optical flow nowcasting 1. Introduction Quantitative precipitation monitoring and forecast is an important issue in water management in flood forecasting and in predicting hazardous conditions. Specific problems are the distinction of rain from snow 1 the monitoring of basins subject to floods or of areas prone to landslides 2 and