Air pollution trends measured from Terra: CO and AOD over industrial, fire-prone, and background regions

Rebecca R. Buchholz (1) , Helen M. Worden (1) , Mijeong Park (1) , Gene Francis (1) , Merritt N. Deeter (1) , David P. Edwards (1) , Louisa K. Emmons (1) , Benjamin Gaubert (1) , John Gille (1) , Sara Martínez-Alonso (1) , Wenfu Tang (1) , Rajesh Kumar (2) , James Drummond (3, 4) , Cathy Clerbaux (5, 6) , Maya George (6) , Pierre-François Coheur (5) , Daniel Hurtmans (5) , Kevin W. Bowman (7, 8) , Ming Luo (7) , Vivienne H. Payne (7) , John R. Worden (7) , Mian Chin (9) , Robert Levy (9) , Juying Warner (10) , Zigang Wei (11) , Susan Kulawik (12)

1 ACOML - Atmospheric Chemistry Observations and Modeling Laboratory
2 RAL - Research Applications Laboratory [Boulder]
3 University of Toronto
4 Dalhousie University [Halifax]
5 SQUARES - Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing
6 TROPO - LATMOS
7 JPL - Jet Propulsion Laboratory
8 JIFRESSE - UCLA Joint Institute for Regional Earth System Science and Engineering
9 GSFC - NASA Goddard Space Flight Center
10 AOSC - Department of Atmospheric and Oceanic Science [College Park]
11 NESDIS - NOAA National Environmental Satellite, Data, and Information Service
12 ARC - NASA Ames Research Center

Following past studies to quantify decadal trends in global carbon monoxide (CO) using satellite observations, we update estimates and find a CO trend in column amounts of about −0.50 % per year between 2002 to 2018, which is a deceleration compared to analyses performed on shorter records that found −1 % per year. Aerosols are co-emitted with CO from both fires and anthropogenic sources but with a shorter lifetime than CO. A combined trend analysis of CO and aerosol optical depth (AOD) measurements from space helps to diagnose the drivers of regional differences in the CO trend. We use the long-term records of CO from the Measurements of Pollution in the Troposphere (MOPITT) and AOD from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. Other satellite instruments measuring CO in the thermal infrared, AIRS, TES, IASI, and CrIS, show consistent hemispheric CO variability and corroborate results from the trend analysis performed with MOPITT CO. Trends are examined by hemisphere and in regions for 2002 to 2018, with uncertainties quantified. The CO and AOD records are split into two sub-periods (2002 to 2010 and 2010 to 2018) in order to assess trend changes over the 16 years. We focus on four major population centers: Northeast China, North India, Europe, and Eastern USA, as well as fire-prone regions in both hemispheres. In general, CO declines faster in the first half of the record compared to the second half, while AOD trends show more variability across regions. We find evidence of the atmospheric impact of air quality management policies. The large decline in CO found over Northeast China is initially associated with an improvement in combustion efficiency, with subsequent additional air quality improvements from 2010 onwards. Industrial regions with minimal emission control measures such as North India become more globally relevant as the global CO trend weakens. We also examine the CO trends in monthly percentile values to understand seasonal implications and find that local changes in biomass burning are sufficiently strong to counteract the global downward trend in atmospheric CO, particularly in late summer.

Mots clés: Carbon monoxide; AOD; NASA/Terra satellite; Trend; Interannual variability

Domaines: Sciences de l'environnement

Rebecca R. Buchholz, Helen M. Worden, Mijeong Park, Gene Francis, Merritt N. Deeter, et al.. Air pollution trends measured from Terra: CO and AOD over industrial, fire-prone, and background regions. Remote Sensing of Environment, 2021, 256 (April), pp.112275. ⟨10.1016/j.rse.2020.112275⟩. ⟨insu-03121805⟩