This pair of images compares preliminary estimates of column-averaged volume mixing ratios of carbon dioxide, or XCO2, from OCO-2 glint observations over the ocean to those generated by the NASA Goddard Earth Observing System Model, Version 5 (GEOS-5). The large scale features are quite similar, but there are subtle differences that are being studied to determine whether they indicate biases in these early OCO-2 XCO2 estimates or limitations of the model. Over time, these comparisons are expected to substantially improve the accuracy and reliability of both the measurements and the models.