January 10, 2020
How large-scale atmospheric circulation changes drive fire activity in Equatorial Asia and southeastern Siberia?
김진수 박사 (University of Edinburgh)
2020년 1월 15일 (수) 14:00
Fire activity in Equatorial Asia shows large interannual variability. Teleconnections by El Niño‐Southern Oscillation and Indian Ocean Dipole are linked to drought and fire events; however, we found here that significant role of local Sea Surface Temperature (SST) over the Banda Sea in interannual variability of Equatorial Asian burned area in October even after removing the linear effects of teleconnections. October is the transient period from dry to wet season and strengthened seasonal circulation in October leads to a negative SST anomaly through Wind‐Evaporation‐SST mechanism. This anomalous local air‐sea interaction sustains the dry season into October and stronger fire activity. Moreover, we found that the sensitivity of precipitation to SST is higher in October than in other months, hence fires in Equatorial Asia can be sensitively driven by local SST changes. Identification of this sensitivity will underpin better predictions of fire activity and air quality in Equatorial Asia.
Carbon release through boreal fires could considerably accelerate Arctic warming; however, boreal fire occurrence mechanisms and dynamics remain largely unknown. Here, we analyze fire activity and relevant large-scale atmosphericconditions over southeastern Siberia, which has the largest burned area fraction in the circumboreal and high-level carbon emissions due to high-density peatlands. It is found that the annual burned area increased when a positive Arctic Oscillation (AO) takes place in early months of the year, despite peak fire season occurring 1 to 2 months later. A local high-pressure system linked to the AO drives a high-temperature anomaly in late winter, causing premature snowmelt. This causes earlier ground surface exposure and drier ground in spring due to enhanced evaporation, promoting fire spreading. Recently, southeastern Siberia has experienced warming and snow retreat; therefore, southeastern Siberia requires appropriate fire management strategies to prevent massive carbon release and accelerated global warming.