Research on Method of Analyzing Weather Satellite Image Data by 3D Display

- Image Analysis of Tornados on Hokkaido Terrain -

Abstract

This paper relates to the feasibility of prediction of tornados. It discusses the environment and features of occurrence of tornados by Rawinsonde observation and Doppler radar observation. Here, we attempt analysis using infrared images of weather data showing cumulonimbus clouds etc. including terrain conditions. The 3D terrain of Hokkaido is displayed using digital data of elevation. In this case, the display of the terrain becomes clearer and the time for image display becomes faster by excluding ocean and lake areas. Here, the elevation of the 3D display of terrain is plotted on the Z-axis. Similarly, the brightness values of the image data of the weather satellite Himawari are plotted on the Z-axis. These are overlaid on the terrain to display an image in three dimensions. At that time, the low brightness values of the image are deleted. Due to this, display of high brightness, thick clouds is attained. Moreover, in the same region of terrain and weather data, compared with terrain data, weather data has fewer pixels and is coarser, so the data is linearly interpolated and a Fast Fourier Transform is used to prepare a Fourier series approximation curve to thereby increase the resolution of the image 3-fold. Here, the weather data on the terrain of Hokkaido on November 7, 2006, between 12:00 noon and 2:00 pm when a tornado occurred in Saroma-cho is analyzed and the change of the image on the terrain is considered.