Supporting data for "Direct observation of changing NOx lifetime in North American cities"
Laughner, Joshua; Cohen, Ronald (2019), Supporting data for "Direct observation of changing NOx lifetime in North American cities", Dryad, Dataset, https://doi.org/10.6078/D1RQ4V
NOx lifetime can be directly observed from space, and has a nonlinear relationship with its own concentration. At high NOx concentrations, NOx lifetime decreases with decreasing concentration, but at intermediate concentrations, the reverse is true. Here we show that urban NOx lifetime in North America has changed between 2005 and 2014. The shape of these changes is qualitatively consistent with a steady-state model of NOx lifetime with decreasing NOx emissions. The pattern of change suggests that NOx-limited chemistry now controls urban NOx 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.
National Aeronautics and Space Administration, Award: NNX14AK89H
National Aeronautics and Space Administration, Award: NNX15AE37G
Smithsonian Astrophysical Observatory, Award: SV3-83019