Climate on Abnormal Occurrence of Wildfires around Eurasia and Northern America

A great many wildfires sometimes occurred around Eurasia and Northern America: especially, Siberia and Mongolia in summer of 1998 and 2002. Generally speaking, the wildfires are caused by extreme hot and dry conditions. We could see what was happened in 1998 (Kimura et al., 2002, 2003). Now we can analyze the climatic conditions in 2002. Then we found that the climatic conditions in 1998 and 2002 from Siberia to Northern America. Indeed, in 1998 summer it was high temperature and little precipitation, and it was hotter and drier than that of 2002 summer. We can see the pressure distribution at Sea Level and 500hPa in summer. The ridge or blocking high pressure at 500hPa level is seen over the western Siberia. It corresponds to the high pressure area at Sea Level in Siberia. And also the waves at the 500hPa meander effect to the climate of North America. Next, seasonal change in summer is picked up, as wildfire had seasonal change. Sometimes it rains, but sometimes no precipitation continued more than 2 weeks in Siberia. During this period, the SLP had been high level, and southern component of wind continued to blow. This phenomenon means hot and dry condition was kept. The low relative humidity air mass moved eastward gradually, but sometimes it covered for many days. While this climatic condition continues, many wildfires occurred. In addition, a olt of wildfires were occuered in Alaska in 2004 summer. We are analizing about it.