资源环境科技发展态势分析平台

In this study, the spatial variability in precipitation at a 0.1 degrees scale is investigated using long-term data from the Tropical Rainfall Measuring Mission Precipitation Radar. Marked regional heterogeneities emerged for orographic rainfall on characteristic scales of tens of kilometers, high concentrations of small-scale systems (<10 km) over alpine areas, and sharp declines around mountain summits. In detecting microclimates, an additional concern is suspicious echoes observed around certain geographical areas with relatively low rainfall. A finescale land-river contrast can be extracted in the diurnal behavior of rainfall in medium-scale systems (10-100 km), corresponding to the course of the Amazon River. In addition, rainfall enhancement over small islands (0.1 degrees-1 degrees) was identified in terms of the storm scale. Even 0.1 degrees-scale flat islands experience more rainfall than the adjacent ocean, primarily as a result of localized small or moderate systems. By contrast, compared with small islands, high-impact large-scale systems (>100 km) result in more rainfall over the adjacent ocean. Finescale hourly data represented the abrupt asymmetric fluctuation in rainfall across the coastline in the tropics and subtropics (30 degrees S-30 degrees N). Significant diurnal modulations in the rainfall due to largescale systems are found over tropical offshore regions of vast landmasses but not over small islands or in the midlatitudes between 30 degrees and 36 degrees. Rainfall enhancement over small tropical islands is generated by abundant afternoon rainfall, which results from medium-scale storms that are regulated by the island size and inactivity of rainfall over coastal waters.