First high-resolution tropospheric NO2observations from the Ultraviolet Visible Hyperspectral Imaging Spectrometer (UVHIS)

Abstract

We present a novel airborne imaging differential optical absorption spectroscopy (DOAS) instrument: the Ultraviolet Visible Hyperspectral Imaging Spectrometer (UVHIS), which is developed for trace gas monitoring and pollution mapping. Within a broad spectral range of 200 to 500 double low line nm and operating in three channels, the spectral resolution of UVHIS is better than 0.5 double low line nm. The optical design of each channel comprises a fore-optics with a field of view (FOV) of 40 double low line g, an Offner imaging spectrometer and a charge-coupled device (CCD) array detector of double low line 1032×1072 pixels. A first demonstration flight using UVHIS was conducted on 23 June 2018, above an area of approximately 600 double low line km2 in Feicheng, China, with a spatial resolution of about double low line 25 m×22 double low line m . Measurements of nadir backscattered solar radiation of channel 3 are used to retrieve tropospheric vertical column densities (VCDs) of double low line NO2with a mean total error of double low line 3.0×1015 double low line molec cm-2. The UVHIS instrument clearly detected several emission plumes transporting from south to north, with a peak value of double low line 3×1016 double low line molec cm-2 in the dominant one. The UVHIS double low line NO2vertical columns are consistent with the ground-based mobile DOAS observations, with a correlation coefficient of 0.65 for all co-located measurements, a correlation coefficient of 0.86 for the co-located measurements that only circled the steel factory and a slight underestimation for the polluted observations. This study demonstrates the capability of UVHIS for double low line NO2local emission and transmission monitoring.