Free tropospheric nitrogen dioxide concentrations from cloud-slicing TROPOMI

Seasonal multiyear mean nitrogen dioxide (NO₂) mixing ratios in the free troposphere (300-700 hPa) obtained by applying cloud-slicing to total column densities of NO₂ from the TROPOspheric Monitoring Instrument (TROPOMI). Years averaged over are given in the filenames. Data are global coverage on a 1 degree horizontal grid. The cloud-slicing technique is mostly consistent with the approach detailed in the open access, peer-reviewed Horner et al. (2024) paper, except that the target pressure range is 300-700 hPa to cover the full extent of the free troposphere and filtering to remove cloud-sliced NO₂ data that fall statistically below zero is relaxed from (slope_error + slope) to (2*slope_error + slope), where the slope is the Theil-Sen regression slope obtained from regressing cloud top heights and total NO₂ columns above optically thick clouds. These methodological adjustments are made for comparison to cloud-sliced NO₂ obtained from the geostationary Tropospheric Emissions: Monitoring of Pollution (TEMPO) that has a limited viewing domain covering North America.