Intercomparison of Pandora surface and vertical profile NO2 retrievals with in-situ network measurements and airborne observations across the Eastern USA

Trace gas total and tropospheric/stratospheric column retrievals from the Pandora instruments across the Pandonia Global Network (PGN) have played a key role in satellite validation. With the addition of multi-axis differential optical absorption spectroscopy (MAX-DOAS) retrievals to the latest Pandora processing software (Blick v1.8), the PGN now generates surface and vertically-resolved trace gas measurements that will further aid in future satellite product validation. The MAX-DOAS retrievals developed for the Pandora instrument rely upon simple assumptions and measurements and do not require complex radiative transfer calculations, allowing for the columns to be retrieved at a sub-hourly timescale. In this presentation, we give a brief overview of the theory and measurements behind the Pandora MAX-DOAS retrievals and provide an evaluation of the MAX-DOAS NO2 products. For the evaluation we show an intercomparison of PGN NO2 surface products with co-located surface network measurements taken from the US Environmental Protection Agency Air Quality System (EPA AQS) database.  We also compare Pandora NO2 vertical profiles with profiles collected from both sonde and aircraft measurements in the Eastern United States.