近赤外レーザを利用した降水粒子観測プローブの開発

Abstract

A polarimetric radar is used forecast of rain. The advantage of this radar is able to observe cloud on a real-time in wide area. But rain–rate estimated by radar includes an error. The radar reflectivity factor is depend on hydrometeor shape (raindrop, snowflake, etc…) and Drop Size Distribute (DSD) in sensing area. Currently, advance of precise estimation algorithm by direct observation (Balloon observation, aircraft observation) in radar beam is becoming important. This study develops a laser hydrometeor imaging probe with capability of DSD measurement (Laser Probe) for balloon observation. Laser Probe is consists Laser Diode(LD), Line Photo Diode (LPD) and circuits for data processing. The horizontal resolution is 0.125 mm and line-rate is 30 kHz. A accuracy experiment and a rainfall observation by using the probe are carried out. From accuracy experiment with grass ball, measurement error is within 1 pixel (0.125 mm). The next, rain observation was performed using laser probe with impact type disdrometer RD69 and DSD from observation result is compared. The probe DSD shape is similar to RD69 DSD, however the number of density by Laser Probe is less than that by RD69.