Improvement of interpolation techniques for APHRO_PR, a new gauge-based high-resolution daily precipitation data
In this project, we have collected a huge number of rain-gauge data, most of which have not been available for public use. In addition, we have developed following new interpolation techniques. 1) Modified Shepard type interpolation considering topographical effect. 2) Catch-ratio correction of solid-form precipitation. Owing to the former scheme, precipitation distribution pattern is much improved especially in mountainous area, because of the new method calculates weight function with considering local topographical features to precipitation, while the original Shepard type scheme has no consideration without horizontal distance. In the latter scheme, correct ratio is derived by local wind speed and rain/snow distinction, which are calculated by atmospheric reanalysis data. This method decreases underestimation bias of winter precipitation amount in middle-high latitudes.