Seven years of continuous methane observations at a remote boreal site in Ontario, Canada

Abstract

Abstract. A 7-year record (1990)(1991)(1992)(1993)(1994)(1995)(1996) of continuous atmospheric methane (CH4) measurements is presented from a remote midcontinental monitoring station at Fraserdale, Ontario (49ø53'N, 81ø34'W). Ninety-six air samples per day were measured with a fully automated gas chromatograph with flame ionization detection. Five-day Lagrangian back trajectories over the 7-year period were used to establish a climatology in the region of the station. The site is predominantly influenced by air flow from northern and high-latitude regions and therefore uniquely positioned to monitor wetland emissions. During winter, CH 4 concentration time series from Fraserdale often match the short-term variability observed at the high Arctic monitoring station at Alert, Northwest Territories (82ø27'N, 61ø31'W). During summer, due to diurnal changes of vertical mixing in the boundary layer, large diurnal cycles in CH 4 mixing ratio up to 150 ppb are observed. The data selected for the afternoon, when the boundary layer is well-mixed, are representative of a larger spatial scale. The mean annual cycle of CH 4 at Fraserdale determined using these selected data is significantly different from annual cycles at other mid-and highnorthern latitude sites thus providing key information for global atmospheric CH 4 models. In late summer the annual cycle at Fraserdale shows a distinct secondary maximum in CH 4. This is the result of advection of air with enhanced CH 4 due to emissions from the extensive wetland areas to the north and northwest. The average growth rate (using selected data) for the period was 5.6 ppb yr -• with a growth rate pattern that is slightly different and out of phase with growth rate changes observed at other high-latitude observing sites by 2 to 6 months. 15,995

The role of scavenging in the seasonal transport of black carbon and sulfate to the Arctic

“…Semi-continuous measurements of CO at BRW are made using gas chromatography with hot mercuric reduction detection [Novelli et al, 1992]. At ALT, a nickel catalyst is used to oxidize CO to CO 2 , which is then measured with gas chromatography using a flame ionization detector [Worthy et al, 1998]. Meteorological measurements are described by Herbert et al [1986].…”

Magnitude and seasonality of wetland methane emissions from the Hudson Bay Lowlands (Canada)

“…For Fraserdale we sample the daily data averaged over the 1700-1900 local time window, when the surface measurements are most representative of a relatively deep mixed layer (Worthy et al, 1998), and further select for surface winds from the northern quadrants, when direct influence from the HBL can be expected (Fig. 1).…”

“…To further investigate the magnitude and seasonal onset of HBL emissions we used 2004-2008 surface data at Fraserdale and Alert collected by Environment Canada, with Alert serving as an Arctic background site against which the HBL influence at the Fraserdale downwind site can be referenced (Worthy et al, 1998). For Fraserdale we sample the daily data averaged over the 1700-1900 local time window, when the surface measurements are most representative of a relatively deep mixed layer (Worthy et al, 1998), and further select for surface winds from the northern quadrants, when direct influence from the HBL can be expected (Fig.…”

Application of stable isotope analysis for improved understanding of the methane budget: comparison of TROICA measurements with TM3 model simulations

“…Western Siberia accounts for about 20% of the global wetland emissions (Aselmann and Crutzen 1989;Kuhlmann et al 1998;Worthy et al 1999;Bohn et al 2007).…”