Urban application of the AOTF-based NO2 camera
- 1Department of Solar Radiation in Atmospheres, Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, 1180, Belgium
- 2Serco, Frascati, 00044, Italy
- 3Department of Physics, Sapienza University, Roma, 00185, Italy
- 4Faculty of Aerospace Engineering, Technische Universiteit Delft, Delft, 2629, The Netherlands
To date, efforts to map ground-level NO2 distribution have primarily utilized visible-light scanning grating spectrometers, such as MAX-DOAS and Pandora. Although these instruments boast high retrieval accuracy, their spatiotemporal resolution remains relatively low, limiting the detection of dynamic features and strong spatial gradients.
In recent years, a novel passive remote sensing instrument called the NO2 camera was developed at the Royal Belgian Institute for Space Aeronomy (BIRA-IASB). This instrument aims to measure 2D distributions of NO2 slant column densities (SCDs) with enhanced spatiotemporal resolution over both extensive areas and in point-source plumes. Central to this instrument is the acousto-optical tunable filter (AOTF), providing both sufficient spectral resolution (~0.7nm) for resolving NO2 absorption cross-section structures and tunability across a broad spectral range.
The measurement approach involves sequential acquisitions of monochromatic images of a scene. A hypercube is constructed by tuning the AOTF to specific wavelengths within the 440-450nm range. This hypercube is a 3D array with two spatial dimensions and one spectral axis.
Conventional methods, such as DOAS, process the acquired light spectrum for each pixel's field of view to retrieve NO2 SCD. The hypercube resulting from a measurement with this AOTF-based NO2 camera is a 512x512 array of NO2 SCD values, taken at approximately 50 different wavelengths collected in around 1 minute, achieving a spatial sampling of less than 1 m, from distance of 1 km. Due to this high spatial resolution of the NO2 camera, the pixels that will be processed can be selected very carefully.
Under the QA4EO IDEAS+ framework, the NO2 camera has been selected for further development. At EGU, we will present the results from the associated measurement campaign, performed in spring 2024 on the rooftop of the Sapienza University in Rome.
This work is partially supported by the QA4EO contract QA4EO/SER/SUB/33.
How to cite: Busschots, C., Gramme, P., Baker, N. C., Dekemper, E., Casadio, S., Iannarelli, A. M., Di Bernardino, A., and Vanhamel, J.: Urban application of the AOTF-based NO2 camera , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15754, https://doi.org/10.5194/egusphere-egu24-15754, 2024.
