Boreal forest fires in 1997 and 1998: a seasonal comparison using transport model simulations and measurement data

[摘要] Forest fire emissions have a strong impact on the concentrations of trace gases andaerosols in the atmosphere.In order to quantifythe influence ofboreal forest fire emissions on theatmospheric composition, the fire seasons of 1997and 1998 are compared in this paper. Fire activity in 1998 wasvery strong, especially over Canada and Eastern Siberia, whereas itwas much weaker in 1997. According to burned area estimates the burning in 1998 was more than six timesas intense as in 1997. Based on hot spot locations derived from ATSR (Along TrackScanning Radiometer) data and official burned area data, fireemissions were estimated and their transport was simulated witha Lagrangian tracer transport model. Siberian and Canadian forest firetracers were distinguished to investigate the transport of bothseparately. The fire emissions were transported even overintercontinental distances. Due to the El Niño inducedmeteorological situation, transport from Siberia to Canada was enhanced in 1998.Siberian fire emissions were transported towards Canada andcontributed concentrations more than twice as high as those due toCanada's own CO emissions by fires. In 1998 both tracers arrive at higherlatitudes over Europe, which is due to a higher North AtlanticOscillation (NAO) index in 1998.The simulated emission plumes are compared to CMDL (Climate Monitoringand Diagnostics Laboratory) CO₂ and COdata, Total Ozone Mapping Spectrometer (TOMS) aerosol index (AI) data andGlobal Ozone Monitoring Experiment (GOME) tropospheric NO₂ andHCHO columns.All the data show clearly enhanced signals during the burning seasonof 1998 compared to 1997.The results of the model simulation are ingood agreement with ground-based as well as satellite-based measurements.

[学科分类] 大气科学