This thesis analyzes the effectiveness of spatially averaged Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements at regular azimuth angle intervals on an hourly basis to validate satellite based DOAS measurements. Off-Axis MAX-DOAS Measurements taken in Blacksburg, Virginia, between November 2021 and April 2022 with an evenly distributed set of measurements were averaged every hour and compared to Direct Sun measurements, also averaged every hour. Comparisons of the difference in average measurement from both measuring strategies, as well as the distribution standard deviations of hourly measurements suggests that the NO₂ distribution around Blacksburg is homogeneous. In order to test the effectiveness of this sampling strategy,in an inhomogeneous location, the LOTOS-EUROS high resolution (1kmx1km) chemical transport model was used to simulate profiles and vertical column densities of real measurements taken during the TROLIX'19 Field Campaign. The LOTOs-EUROS model was used to simulate vertical profiles as well as Vertical Column Densities based on real MAX-DOAS measurements as well as TROPOMI viewing geometry. While the individual ground measurements were not equal to the TROPOMI profile, the TROPOMI profile is approximately the average of the profiles of measurements made within the hour of TROPOMI overpass. / M.S. / This thesis analyzes the effectiveness of spatially averaged Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements at regular intervals of angles offset from due North on an hourly basis to validate satellite based DOAS measurements. MAX-DOAS Measurements taken relative to the position of the sun in Blacksburg, Virginia, a low NO₂ location, between November 2021 and April 2022 to determine the effectiveness of a generalized measuring strategy for satellite validation in low pollution environments. An evenly distributed set of measurements were averaged every hour and compared to measurements taken in the direction of the sun, also averaged every hour, to determine if the variability of NO₂ around Blacksburg is high enough to require a generalized sampling strategy, or if the NO₂ distribution is homogeneous enough to be accurately validated with Direct Sun measurements only.. Comparisons of the difference in average measurement from both measuring strategies, as well as the distribution of standard deviations of hourly measurements suggests that the NO₂ distribution around Blacksburg is low. In order to test the effectiveness of this sampling strategy in a higher pollution location with many sources and sinks of NO₂, the data from the LOTOS-EUROS high resolution (1kmx1km) chemical transport model run by the Royal Dutch Meteorological Institute for the TROLIX'19 Field Campaign was used to simulate vertical distributions of NO₂ and vertical column densities of measurements taken during the field campaign. The LOTOS-EUROS model was used to simulate vertical distributions of NO₂ as well as Vertical Column Densities based on real MAX-DOAS measurements as well as viewing geometry seen by the TROPOspheric Monitoring Instrument (TROPOMI) satellite-based instrument. While the individual ground measurements were not equal to the vertical distribution seen by TROPOMI, the TROPOMI vertical distribution is approximately the average of the vertical distributions of measurements made within an hour of TROPOMI passing over Rotterdam.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/110863 |
| Date | 21 June 2022 |
| Creators | Earley, Jeffrey D. |
| Contributors | Electrical and Computer Engineering, Lind, Elena, Foroutan, Hosein, Zhu, Yizheng |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/pdf |
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