FTIR measurements of biomass burning species in the Arctic

Abstract:

We present time series of the total column amounts of carbon monoxide (CO), hydrogen cyanide
(HCN), acetylene (C2H2), ethane (C2H6), formaldehyde (H2CO), formic acid (HCOOH) and methanol
(CH3OH) obtained by Fourier Transform Infrared (FTIR) spectrometer measurements at three Arctic
sites. Two are located in the high Arctic at Eureka, Nunavut (80.02°N, 86.42°W) and Thule, Greenland
(76.53°N , 68.74°W), and the third is at Poker Flat, Alaska (65.11°N, 147.42°W).

Total column amounts of each target species are obtained using the SFIT4 retrieval algorithm based on
the optimal estimation method, along with spectral line parameters from the HITRAN 2008
spectroscopic database.

The total column time series allow for biomass burning events to be identified at all three sites by
enhancements of the total columns above ambient levels. HYSPLIT back-trajectories and MODIS fire
hot spot data are used to determine the burning source regions and the travel time durations of the
plumes. The seasonal variabilities of the longer-lived species of CO, HCN, C2H2 and C2H6 are primarily
determined by reactions with OH and long-range transport, while those of the shorter-lived species of
H2CO, HCOOH, CH3OH are most influenced by biogenic emissions and short-range transport. The
varying lifetimes of these species and the independent measurements at the three sites allow for the
transport pathways to be investigated. By accounting for the effect of the aging of the smoke plumes,
the measured FTIR enhancement ratios are corrected to obtain emission ratios and emission factors,
which are needed to improve the simulation of fire emissions in chemical transport models.