Atmospheric oxygen concentration: significant factor neglected in fire models

Abstract Wildfires have great impact on the global ecosystem and human society, so the prediction and prevention of wildfires is necessary. This study used the MOD14A2 data, the NCEP/NCAR and ERA5 Reanalysis data, the GFEDv4 data and the Scripps O2 data to analyze the correlations between the area of wildfires and meteorological elements, and used the oxygen concentration to improve the McArthur Forest Fire Danger Index (FFDI). The following results were obtained: 1) During 2001 to 2015, the year of 2002 was the year with the most wildfires in the world, and August was the month with the most wildfires in a year. Northern Africa, Southern Africa and South America are the main wildfires-affected areas, accounting for nearly 80% of the global wildfires area in these 15 years. 2) Globally, the correlation coefficient between temperature and wildfires area is 0.47; for wind speed, it is 0.17; for precipitation, it is -0.41; for relative humidity, it is -0.19; and for oxygen concentration, it is more than 0.6. 3) The improved McArthur Forest Fire Danger Index (FFDInew) constructed by using the original FFDI and oxygen concentration can better reflect the fire risk in Australia. This study emphasized the important impact of changes in oxygen concentration on fires. It is of great significance for the management, prediction and prevention of wildfires.