Spatial distributions of <i>X</i><sub>CO<sub>2</sub></sub> seasonal cycle amplitude and phase over northern high-latitude regions

Abstract. Satellite-based observations of atmospheric carbon dioxide (CO2) provide measurements in remote regions, such as the biologically sensitive but undersampled northern high latitudes, and are progressing toward true global data coverage. Recent improvements satellite retrievals total column-averaged dry air mole fractions CO2 (XCO2) from NASA Orbiting Carbon Observatory 2 (OCO-2) have allowed for unprecedented coverage high-latitude while maintaining acceptable accuracy consistency relative to ground-based observations, finally providing sufficient spring autumn analysis satellite-observed XCO2 seasonal cycles across a majority terrestrial regions. Here, we present an calculated OCO-2 temperate, boreal, tundra subdivided into 5? latitude by 20? longitude zones. We quantify cycle amplitudes (SCAs) annual half drawdown day (HDD). SCAs good agreement with at five sites, show very close model estimates Copernicus Atmosphere Monitoring Services (CAMS) inversion-optimized greenhouse gas flux v19r1 CarbonTracker2019 (CT2019B). Model GEOS-Chem simulation version 12.7.2 underlying biospheric fluxes (GC-CT2019) yield larger magnitude spread over range than those CAMS, CT2019B, or OCO-2; however, GC-CT2019 still exhibit similar spatial distribution regions that OCO-2. Zones Asian boreal forest were found exceptionally large SCA early HDD, both distinct longitudinal gradient increasing west east Eurasian continent. In spanning latitudes 47 72? N, gradients HDD least pronounced latitudinal gradients, suggesting role transport patterns defining distributions seasonality these surface contact tracers largest occur areas greatest land surfaces, integrated 15–30 d. The correlation is stronger within each zone. This indicates accumulation during major driver regional variations SCA.