NO_x lifetime can be directly observed from space, and has a nonlinear relationship with its own concentration. At high NO_x concentrations, NO_x lifetime decreases with decreasing concentration, but at intermediate concentrations, the reverse is true. Here we show that urban NO_x lifetime in North America has changed between 2005 and 2014. The shape of these changes is qualitatively consistent with a steady-state model of NO_x lifetime with decreasing NO_x emissions. The pattern of change suggests that NO_x-limited chemistry now controls urban NO_x lifetime.

This dataset was produced by doi: 10.5281/zenodo.2629580

Briefly, NO2 column densities from the Berkeley High Resolution (BEHR) NO2 product, v3.0B (daily) were aligned according to wind direction and integrated in the across-wind direction to product line densities. These line densities were fit with exponentially modified Gaussian functions, and NOx lifetimes derived from the characteristic distance of the exponential and the average wind speed.

This dataset consists of both the native Matlab .mat files and netCDF versions of those files that contain the line densities and EMG fitting results for 49 cities in North America.  The analysis code at doi: 10.5281/zenodo.2629580 uses the .mat files; the netCDF files are provided for users without access to Matlab.