Niwot Ridge, Colorado, United States
|Site Latitude||40° 3' 11.16" N (40.05310 °N)|
|Site Longitude||105° 35' 11.04" W (-105.58640 °E)|
|Site Elevation||3523.0 masl|
|Dataset||co2_nwr_surface-insitu_3_nonlocal (GLOBALVIEW identifier NWR_03C0)|
|Assimilated||Yes Switch to unassimilated subset|
|Selection scheme||Non-locally influenced hourly values determined when CO2 variability is low and vertical gradients are small|
|Data provider||Britton Stephens, National Center for Atmospheric Research, 3090 Center Green Drive, Boulder, CO 80301, United States|
|Partner(s)||No partner information available.|
|Download these data via ObsPack.|
(a) Time series of CO2 mole fractions, both simulated and observed, at this CarbonTracker observation site. In the top panel, measured mole fractions (open black circles) are plotted along with CarbonTracker simulated values (filled light blue circles). Any observations that CarbonTracker can not assimilate successfully are shown as filled red circles.
(b) The time series of model residuals--the difference between the simulated and measured mole fractions--shown with dark green filled circles. These residuals should be uncorrelated in time, unbiased (i.e., have a mean of zero), and distributed normally. Also shown in the lower panel is the imposed model-data mismatch ("MDM", orange lines), which in part defines the rejection criterion (see documentation). Any model first guess value which is more than three times the MDM away from zero, after accounting for potential adjustments to the simulated value due to optimizing fluxes, is rejected by the optimization system. Rejected values, if there are any, are shown with filled red circles.
(c) Summary statistics for model residuals from to . Residuals are defined as simluated values minus observed 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 ppm of CO2. The time period over which these quantities are computed is set by the graphs (a) and (b).
(d) Seasonal histograms of residuals