Direct measurements of the seasonality of emission factors from savanna fires in northern Australia

TY - JOUR

T1 - Direct measurements of the seasonality of emission factors from savanna fires in northern Australia

AU - Meyer, C. P.

AU - Cook, G. D.

AU - Reisen, F.

AU - Smith, Thomas

AU - Tattaris, M.

AU - Russell-Smith, J.

AU - Maier, S. W.

AU - Yates, C. P.

AU - Wooster, M. J.

PY - 2012/10/27

Y1 - 2012/10/27

N2 - Current good practice guidelines for national greenhouse gas inventories requires that seasonal variation in emission factors from savanna fires be considered when compiling national accounts. African studies concluded that the emission factor for methane decreases during the dry season principally due to curing of the fuels. However, available data from Australian tropical savannas shows no effect of seasonality on emission factors, consistent with observations that the fine fuels appear to cure fully soon after the start of the fire season. To test whether the seasonality in greenhouse gas emission factors reported for Africa also occurs in Australia, methane and nitrous oxide emission factors were measured in early and in late dry season fires in Western Arnhem Land, a region typical of much of the northern Australia savanna zone. We found no significant seasonality in methane emission factors, but there was substantial variation in emission factors associated with inter-fire differences in vegetation and fuel. This variation could be explained almost completely by combustion efficiency. Nitrous oxide emission factors were not related to combustion efficiency but showed some variation across vegetation and fuel size class. Both methane and nitrous oxide emission factors were consistent with previous work in northern Australia and with some published values from Africa. The absence of a significant seasonal trend in emission factors indicates that savanna fire emissions in northern Australia can be managed by strategic prescribed burning.

AB - Current good practice guidelines for national greenhouse gas inventories requires that seasonal variation in emission factors from savanna fires be considered when compiling national accounts. African studies concluded that the emission factor for methane decreases during the dry season principally due to curing of the fuels. However, available data from Australian tropical savannas shows no effect of seasonality on emission factors, consistent with observations that the fine fuels appear to cure fully soon after the start of the fire season. To test whether the seasonality in greenhouse gas emission factors reported for Africa also occurs in Australia, methane and nitrous oxide emission factors were measured in early and in late dry season fires in Western Arnhem Land, a region typical of much of the northern Australia savanna zone. We found no significant seasonality in methane emission factors, but there was substantial variation in emission factors associated with inter-fire differences in vegetation and fuel. This variation could be explained almost completely by combustion efficiency. Nitrous oxide emission factors were not related to combustion efficiency but showed some variation across vegetation and fuel size class. Both methane and nitrous oxide emission factors were consistent with previous work in northern Australia and with some published values from Africa. The absence of a significant seasonal trend in emission factors indicates that savanna fire emissions in northern Australia can be managed by strategic prescribed burning.

KW - SENSITIVITY-ANALYSIS

KW - CARBON

KW - STRAW

KW - BURNING EMISSIONS

KW - COMBUSTION

KW - PATTERNS

KW - N2O

KW - SOUTHERN AFRICA

KW - WHEAT

KW - TRACE GASES

U2 - 10.1029/2012JD017671

DO - 10.1029/2012JD017671

M3 - Article

SN - 0148-0227

VL - 117

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

IS - D20

M1 - D20305

ER -