edu.ucar.opensky::articles:16570 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T03:16:17.421783 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7jw8g1b Ground-based direct-sun DOAS and airborne MAX-DOAS measurements of the collision-induced oxygen complex, O₂O₂, absorption with significant pressure and temperature differences 2015-02-15T00:00:00Z publication https://n2t.org/ark:/85065/d7jw8g1b https://doi.org/10.5194/amt-8-793-2015 Spinei, E. author Cede, A. author Herman, J. author Mount, G. author Eloranta, E. author Morley, Bruce McIntyre author Baidar, S. author Dix, B. author Ortega, I. author Koenig, T. author Volkamer, R. author UCAR/NCAR - Library publisher The collision-induced O₂ complex, O₂O₂, is a very important trace gas for understanding remote sensing measurements of aerosols, cloud properties and atmospheric trace gases. Many ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements of the O₂O₂ optical depth require correction factors of 0.75 ± 0.1 to reproduce radiative transfer modeling (RTM) results for a nearly pure Rayleigh atmosphere. One of the potential causes of this discrepancy is uncertainty in laboratory-measured O₂O₂ absorption cross section temperature and pressure dependencies due to difficulties in replicating atmospheric conditions in the laboratory environment. This paper presents ground-based direct-sun (DS) and airborne multi-axis (AMAX) DOAS measurements of O₂O₂ absorption optical depths under actual atmospheric conditions in two wavelength regions (335--390 and 435--490 nm). DS irradiance measurements were made by the Washington State University research-grade Multi-Function Differential Spectroscopy Instrument instrument from 2007 to 2014 at seven sites with significant pressure (778 to 1013 hPa) and O₂O₂ profile-weighted temperature (247 to 275 K) differences. Aircraft MAX-DOAS measurements were conducted by the University of Colorado (CU) AMAX-DOAS instrument on 29 January 2012 over the Southern Hemispheric subtropical Pacific Ocean. Scattered solar radiance spectra were collected at altitudes between 9 and 13.2 km, with O₂O₂ profile-weighted temperatures of 231 to 244 K and nearly pure Rayleigh scattering conditions. Due to the well-defined DS air-mass factors during ground-based measurements and extensively characterized atmospheric conditions during the aircraft AMAX-DOAS measurements, O₂O₂ "pseudo" absorption cross sections, σ, are derived from the observed optical depths and estimated O₂O₂ column densities. Vertical O₂O₂ columns are calculated from the atmospheric sounding temperature, pressure and specific humidity profiles. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright Author(s) 2015. This work is distributed under the Creative Commons Attribution 3.0 License5 None eng geoscientificInformation