Satellite validation strategy assessments based on the AROMAT campaigns

[摘要] The Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaigns took place in Romania in September 2014 and August 2015. They focused on two sites: the Bucharest urban area and large power plants in the Jiu Valley. The main objectives of the campaigns were to test recently developed airborne observation systems dedicated to air quality studies and to verify their applicability for the validation of space-borne atmospheric missions such as the TROPOspheric Monitoring Instrument (TROPOMI)/Sentinel-5 Precursor (S5P). We present the AROMAT campaigns from the perspective of findings related to the validation of tropospheric NO 2 , SO 2 , and H 2 CO . We also quantify the emissions of NO x and SO 2 at both measurement sites. We show that tropospheric NO 2 vertical column density (VCD) measurements using airborne mapping instruments are well suited for satellite validation in principle. The signal-to-noise ratio of the airborne NO 2 measurements is an order of magnitude higher than its space-borne counterpart when the airborne measurements are averaged at the TROPOMI pixel scale. However, we show that the temporal variation of the NO 2 VCDs during a flight might be a significant source of comparison error. Considering the random error of the TROPOMI tropospheric NO 2 VCD ( σ ), the dynamic range of the NO 2 VCDs field extends from detection limit up to 37 σ ( 2.6×10 16  molec. cm −2 ) and 29 σ (2 ×10 16  molec. cm −2 ) for Bucharest and the Jiu Valley, respectively. For both areas, we simulate validation exercises applied to the TROPOMI tropospheric NO 2 product. These simulations indicate that a comparison error budget closely matching the TROPOMI optimal target accuracy of 25 % can be obtained by adding NO 2 and aerosol profile information to the airborne mapping observations, which constrains the investigated accuracy to within 28 %. In addition to NO 2 , our study also addresses the measurements of SO 2 emissions from power plants in the Jiu Valley and an urban hotspot of H 2 CO in the centre of Bucharest. For these two species, we conclude that the best validation strategy would consist of deploying ground-based measurement systems at well-identified locations.

[学科分类] 内科医学