Quantifying daily NO x and CO 2 emissions from Wuhan using satellite observations from TROPOMI and OCO-2

[摘要] Quantification and control of NO x and CO 2 emissions are essential across the world to limit adverse climate change and improve air quality. We present a new top-down method, an improvedsuperposition column model to estimate day-to-day NO x and CO 2 emissions from the large city of Wuhan, China, located in a polluted background. The latest released version 2.3.1 TROPOMI (TROPOspheric Monitoring Instrument) NO 2 columns and version 10r of the Orbiting Carbon Observatory-2  (OCO-2)-observed CO 2 mixing ratio are employed. We quantified daily NO x and CO 2 emissions from Wuhan between September 2019 and October 2020 with an uncertainty of 31 % and 43 %, compared to 39 % and 49 % with the earlier v1.3 TROPOMI data, respectively. Our estimated NO x and CO 2 emissions are verified against bottom-up inventories with minor deviations ( <3  % for the 2019 mean, ranging from −20  % to 48 % on a daily basis). Based on the estimated CO 2 emissions, we also predicted daily CO 2 column mixing ratio enhancements, which match well with OCO-2 observations( <5  % bias, within ±0.3  ppm). We capture the day-to-day variation of NO x and CO 2 emissions from Wuhan in 2019–2020, which does not reveal a substantial “weekend reduction” but does show a clear “holiday reduction” in the NO x and CO 2 emissions. Our method also quantifies the abrupt decrease and slow NO x and CO 2 emissions rebound due to the Wuhan lockdown in early 2020. This work demonstrates the improved superposition model to be a promising new tool for the quantification of city NO x and CO 2 emissions, allowing policymakers to gain real-time information on spatial–temporal emissionpatterns and the effectiveness of carbon and nitrogen regulation in urbanenvironments.

[学科分类] 医学（综合）