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Abstract. Mixing ratio measurements of atmospheric tracers like CO2 can be used to estimate regional surface-air tracer fluxes using inverse methods, involving a numerical transport model. Currently available transport models are either global but rather coarse, or more accurate but only over a limited spatial and temporal domain. To obtain higher-resolution flux estimates within a region of interest, existing studies use zoomed or coupled models. The two-step scheme developed here uses global and regional models sequentially in separate inversion steps, coupled only via the data vector. This provides a nested atmospheric inversion scheme without the necessity of a direct coupled model implementation. For example, the scheme allows an easy nesting of Lagrangian models with their potential of very high resolution into global inversions based on Eulerian models.
Rödenbeck et al. (Wed,) studied this question.