PC base education system for global change monitoring
This system introduces the magneto optical disk ( MO DISK) which is a erasable optical disk, in order to avoid the storage capacity of the personal computer. Although the 130MB hard disk drive is also available and enough to store this database, the advantage of MO DISK is the portable feature like 3.5" floppy disk.
Since the user friendly is needed. A displayed image used the easy understanding color. Therefore. The limitation of this system is that the graphic has to support the 16 colors display.
Data
A database of this system consists of :
- Monthly maximum value of GVI from January 1984 to December 1985. The original GVI data which indicates the weekly density and vigor of green vegetation is the resampling data of the NVI (Normalized Vegetation Index) for the whole earth ( except parts more than 75N and 55S).
- Monthly average value of temperature and rainfall from January 1984 to December 1985, provided by the Japanese Meteorological Agency, detected at 2344 observation stations all over the world.
- Global Vegetation Map which is classified using the seasonal GVI change pattern from 1983 to 1987 [2].
- World elevation data on the mesh size of 5 minute
- Maximum, minimum and average temperature and rainfall at 2344 observation stations all over the world of the record from January 1930 to December 1960.
The reason to select the information of 1984 and 1985 as sample data in this system is that the latter half of 1982 till 1984, Africa was damaged by the drought which was estimated to be the worst in this century and this drought calmed down 1985. Therefore, the difference can be clearly seen from both weather and GVI data.
Since the personal computer a limitation of data storage and data accessing time, a data compression technology is involved. Concerning the displayed image had been classified to 7 categories, it is easy to apply the " run-length" data compression method [2]. Run- length is the most simple data compression method and does not need a big amount of computing time.
Software Functions
The software which drives this system was developed under C language, NEC-DOS environment. The functions of the system are as follows:
All the selective is invoked through a mouse on the screen menu. Fig.3 shows the first menu for selecting the interested area. The size of the area is freely assigned by the user. Fig. 4 shows the second menu after the area was selected. This displayed image composes of vegetation map, boundary line and the location of the observation stations.
Conclusion
In this paper, we have presented the implementation of a software package for global change monitoring based on personal computer. The development of the software is ongoing task to become a GIS for evaluating of the potential productivity of vegetation at the final goal.
Reference
- William K. Pratt, Digital Image Processing , A wiley - interescience, pp. 631 - 635.
- Yoshiaki HONDA and Shunji MURAI, " Vegetation Mapping Using Global Vegetation Index and Weather Data", 10th ACRS, Kuala Lumpur , Malaysia, 1988, PP. A-2-4-1 - A-2-4-6.
