Abstract
We improved the measurement apparatus for convective velocity of ponded water in paddy fields, proposed by Fujimaki et al. (2000). Since the effect of air bubbles accumulated along the sensor on the measurement values was observed, we developed a new equipment to prevent air bubbles from accumulating along the sensor. Another improvement was that the power sources of all measurement devices in the apparatus were exchanged from AC power supplies to DC power supplies. This improvement allowed us to measure convective velocity of ponded water in paddy fields without AC power supplies. The good performance of the improved apparatus was verified by the measurement of convective velocity of ponded water in a paddy field.
