Translation Characteristics of Orographic Precipitation by using the animation of Radar observed Rainfall and Digital Terrain Model.

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The purpose of this study is to understand the effect of orography on translation of storm area or temporal and spatial distribution of rainfall intensity. The 5 min interval radar data observed at 3 sites (Mt Yae, Mt Akagi and Mt Yakushi) and 5km grid Digital Terrain Model are used in this study. The translation characteristics of rainfall area is identified from the animation of radar observed rainfall which is overlaid on the 3-D displayd topography. Based on this analysis, translation pattern of storm area is classified into several cases. In each cases (or each rainfall type), the relationship between the topographic parameters and rainfall intensity is investigated by using the digital terrain model and radar observed rainfall. Elevation, inclination and aspect of a slope, angle between slope aspect and direction of rainfall cloud movement and distance from coastal line are selected as the topographic parameters and correlation between these parameters and time-averaged rainfall intensity, maximum rainfall intensity and total rainfall are examined at each radar cells. The results of this analysis shows that1) angle between slope aspect and direction of rainfall cloud movement and distance from coastal line shows the reasonable correlation between rainfall intensity or time-space distribution.2) orographic effect on translation of storm area or temporal and spatial distribution of rainfall intensity is different in each rainfall type, such as typhoon type, low pressure type, frontal type or thunder storm type.