Site Latitude	89° 58' 48.00" S (-89.98000 °N)	Go to interactive map
Site Longitude	24° 48' 0.00" W (-24.80000 °E)
Site Elevation	2810.0 masl
Site code	SPO
Dataset	c13_SPO_ch4_surface_event_NOAA
Assimilated	Yes
Data provider	Sylvia Englund Michel
Laboratory	NOAA Global Monitoring Laboratory

(a) Time series of δ¹³C-CH₄, both observed and simulated, at this CarbonTracker-CH4 observation site. The The measured stable carbon isotope ratio values relative to ratio values of standard (Pee Dee Belemnite, 0.0112372) (black circles) are plotted along with CarbonTracker-CH4 simulated values with prior fluxes (dark green circles) and posterior fluxes (blue circles).

(b) The time series of model residuals, the difference between the measured and simulated δ¹³C-CH4, for simulation with prior fluxes (dark green circles) and posterior fluxes (blue circles).

(c) Summary statistics for model residuals from to . Residuals are defined as observed values minus simulated values. "Bias" is the mean of the residuals; "std. dev." is the standard deviation, and RMSE is root-mean-square error. All quantities are in permil (‰) of δ¹³C-CH₄. The time period over which these quantities are computed is set by the graphs (a) and (b).