Cover Early detection system of drought in East Asia using NDVI from NOAA/AVHRR data

1. Introduction Drought causes damage to agricultural production and affects the balance of food supply and demand. As Obasi (1994) mentioned, droughts had affected 50% of 2.8 billion people who suffered from weather-related disasters. Moreover, 1.3 million people have died due to the direct and indirect cause of drought during 1967–91. East and South East Asia has the largest population in the world, and it is also one of the largest agriculture-producing regions in the world. If drought occurs in this area, it will affect the balance of food supply and demand all over world. On the other hand, according to Gol'dsberg (1972) using information of vulnerability of major agricultural areas to drought based on the difference between annual precipitation and annual potential evaporation, the negative difference (210 to 2500 mm annually) areas are listed as the frequent intensive drought area. East Asia, especially China, is also one of the largest regions where the drought occurs easily in the world. It is very important to mitigate the damage caused by the drought. Since timely information of drought about its extent and intensity can help