Applied Research on Forest Fire Danger Weather Index

Forest fire is one of the main disasters which damage the ecosystem on the earth.Not only vegetation coverage and charcoal storage can be reduced and atmosphere composition can be changed, but also variation of vegetation structure and biological species can be induced and social economy, human health, and even life can be impacted.And the occurrence of forest-fire is very closely related with the meteorological conditions. Until now domestic and foreign meteorologists and forestry experts have developed a lot of forest fire danger weather indices to estimate and predict possibility of ignition, fire intensity and its spread, as well as difficulty of wildfire control. In this study, 5 calculation methods of forest fire danger weather index are chosen, which have been approved universally or used in state-level early warning service in China, using meteorological observation data of 575 national basic meteorological stations from Jan 1, 1971 to May 31, 2005, to conduct contrast analysis and applied research on the practical effects of these indices in China.The purpose of this study is to examine and discover a best method to find forest fire danger weather index which suits Chinese weather and climatic characteristics, and to improve the operational level of Chinese state-level forest fire danger monitoing and early warning.The results indicate that I_FFD, I_NMC, I_N and I_MN index may be promoted and used in China on a large scale (except in middle and lower reaches and nearby regions of Yangtze River), in which the overall application effect of I_FFD index is the best, and I_MN index takes the second place.I_FFD index is the best in these five kinds of indices not only because of its practical application effect, and because it has the highest corresponding relations with number of the forest-fire in Northeast China and Southwest China, which are two large key Chinese meteorological service regions of forest fire protection, but also of its construction method.I_KBD is not suitable for the most areas of China, but when it is brought into I_FFD as a part of drought factor, the practical application effect of I_FFD is improved significantly.The practical application effect of I_MN is proved to be also good.Its value is closer to the fact than I_N, after weighting coefficient is introduced to control the reduction rate of different precipitation to the index.I_NMC also has good instruction function to forest fire risk, but it is not a patch on I_FFD and I_MN as a whole.One of the causes is that I_NMC is insufficient in considering the previous climatic background.In fact, high or extremely high forest fire danger weather rating is related closely to previous precipitation deficit.