High-Frequency Nitrogen Dioxide Observations over Snow-Covered Surfaces from TEMPO and Ground-Based Measurements

In this presentation TEMPO NO2 observations are evaluated with a focus on snow-covered surfaces. Its ability to capture sharp spatial and temporal gradients in NO2 vertical column densities (VCDs) and surface concentrations are assessed, which are key parameters for assessing air quality and public health impacts. Data from the 2024 Study of Winter Air Pollution in Toronto (SWAPIT), including in situ and mobile MAX-DOAS measurements, are used to assess TEMPO’s precision and accuracy. Additional evaluations are performed at Pandora sites across North America to examine wintertime performance. Comparisons show strong correlations between TEMPO and surface observations, with significant improvements in bias after applying corrections to air mass factors, cloud fraction, and surface albedo (from -32% to -9% over snow).