An updated tropospheric chemistry reanalysis and emission estimates, TCR-2, for 2005–2018

Abstract

Abstract. This study presents the results from the Tropospheric Chemistry Reanalysis version 2 (TCR-2) for the period 2005–2018 at 1.1° horizontal resolution obtained from the assimilation of multiple updated satellite measurements of ozone, CO, NO2, HNO3, and SO2 from the OMI, SCIAMACHY, GOME-2, TES, MLS, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model MIROC-CHASER and an ensemble Kalman filter technique that optimizes both chemical concentrations of various species and emissions of several precursors, which was efficient for the correction of the entire tropospheric profile of various species and its year-to-year variations. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the reanalysis fields for numerous key species on regional and global scales, as well as for seasonal, yearly, and decadal scales, from the surface to the lower stratosphere. The multi-constituent data assimilation brought the model vertical profiles and inter-hemispheric gradient of OH closer to observational estimates, which played an important role in improving the description of the oxidation capacity of the atmosphere and thus vertical profiles of various species. The evaluation results demonstrate the capability of the reanalysis products to improve understanding of the processes controlling variations in atmospheric composition, including long-term changes in near-surface air quality and emissions. The estimated emissions can be employed for the elucidation of detailed distributions of the anthropogenic and biomass-burning emissions of co-emitted species (NOx, CO, SO2) in all major regions, as well as their seasonal, and decadal variabilities. The datasets are available at: https://doi.org/10.25966/9qgv-fe81 (Miyazaki et al., 2019a).

Air Quality Response in China Linked to the 2019 Novel Coronavirus (COVID‐19) Lockdown

“…Chinese emissions are typically low from January to February as a consequence of CNY. Climatological variations referenced to CNY in Figure 1 are derived from our 16‐year (2005–2020) emission time series (Miyazaki, Bowman, Sekiya, et al, 2020). These reductions start about 20 days beforehand and reach their nadir after CNY before recovering about a month later.…”

“…An extended calculation of the Tropospheric Chemistry Reanalysis Version 2 (TCR‐2) (Miyazaki, Bowman, Sekiya, et al, 2020) is used to evaluate emission and concentration changes (Texts S1 and S2 in the supporting information). The data products used in this study have been obtained from the assimilation of multiple satellite measurements of ozone, CO, NO 2 , HNO 3 , and SO 2 from the OMI, TROPOMI, MLS, and MOPITT satellite instruments (Text S3).…”

“…Consequently, health impacts, which we compute based upon population and exposure‐response relationships (Liang et al, 2018), account for the effect of both local and nonlocal emissions changes. For these estimates, we use a multiconstituent satellite data assimilation system (Miyazaki, Bowman, Sekiya, et al, 2020), which simultaneously optimizes concentrations and emissions of various species while taking their complex chemical interactions into account.…”

Evaluation of tropospheric ozone reanalyses with independent ozonesonde observations in East Asia

“…The tropospheric ozone from TCR-2 (Miyazaki et al 2019(Miyazaki et al , 2020; JAMSTEC 2019) is produced by assimilating a set of satellites of diverse atmospheric compositions into a global chemical model of the troposphere, named CHemical AGCM for Study of atmospheric Environment and Radiative forcing (CHASER). This model calculates 88 chemical and 25 photolytic reactions with 47 chemical species (Sudo et al 2002).…”

NOx Emissions Reduction and Rebound in China Due to the COVID‐19 Crisis

“…Bottom‐up inventories are usually updated with few years delay due to the complexity of gathering all statistic information on source sector, land‐use, and sector‐specific emission factors. A top‐down approach using satellite observations has been demonstrated to be able to accurately and quickly provide emission estimates (Miyazaki et al, 2020; Stavrakou et al, 2013). Here we derived the NO x emissions by using the satellite observations and a chemistry‐transport model (CTM).…”