Abstract
This study investigated the effect of local wa-ter flow around the constantan (Co) line of a sensor caused by heating the line on the measured convective velocity of ponded water in a paddy field. Then, a method of cali-brating the sensor, considering this effect, was examined. The output voltages of the sensor at a water temperature of 20◦C were 6 % larger than those at 30◦C when the en-ergy supplied to the Co line was 0.52 W m−2, indicating that an increase in water temperature accelerated the local water flow. Based on this, a method of calibrating the sen-sor while supplying the Co line with 0.13 W m−2 energy was developed. This calibration, which was expressed by a linear function, had a significant correlation (r2 = 0.97) between the sensor output and convective velocities in the 0.0 to 1.25 mm s−1 range.
