31 Mar 2022
31 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Estimating global ammonia (NH3) emissions based on IASI observations from 2008 to 2018

Zhenqi Luo1,2, Yuzhong Zhang1,2, Wei Chen1,2, Martin Van Damme3,4, Pierre-François Coheur3, and Lieven Clarisse3 Zhenqi Luo et al.
  • 1Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, Zhejiang Province, 310024, China
  • 2Institute of Advanced Technology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang Province, 310024, China
  • 3Université libre de Bruxelles (ULB), Spectroscopy, Quantum Chemistry and Atmospheric Remote Sensing (SQUARES), Brussels, Belgium
  • 4BIRA-IASB - Belgian Institute for Space Aeronomy, Brussels, Belgium

Abstract. Emissions of ammonia (NH3) to the atmosphere impact human health, climate, and ecosystems through their critical contributions to secondary aerosol formation. Estimation of NH3 emissions is associated with large uncertainties because of inadequate knowledge about agricultural sources. Here, we use satellite observations from the Infrared Atmospheric Sounding Interferometer (IASI) and simulations from the GEOS-Chem model to constrain global NH3 emissions over the period of 2008–2018. We update the prior NH3 emission fluxes with the ratio between biases in simulated NH3 concentrations and effective NH3 lifetimes against the loss of the NHx family. In contrast to about a factor of two discrepancies between top-down and bottom-up emissions found in previous studies, our method results in a global land NH3 emission of 79 (71–96) Tg a-1, ~30 % higher than the bottom-up estimates. Regionally, we find that the bottom-up inventory underestimates NH3 emissions over the South America and tropical Africa by 60–70 %, indicating under-representation of agricultural sources in these regions. We find a good agreement within 10 % between bottom-up and top-down estimates over the U.S., Europe and eastern China. Our results also show significant increases in NH3 emissions over India (13 % decade-1), tropical Africa (33 % decade-1), and South America (18 % decade-1) during our study period, consistent with the intensifying agricultural activities in these regions in the past decade. We find that inclusion of SO2 column observed by satellite is crucial for more accurate inference of NH3 emission trends over important source regions such as India and China where SO2 emissions have changed rapidly in recent years.

Zhenqi Luo et al.

Status: open (until 03 Jun 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-216', Anonymous Referee #1, 04 May 2022 reply
  • RC2: 'Comment on acp-2022-216', Anonymous Referee #2, 16 May 2022 reply

Zhenqi Luo et al.


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Short summary
We quantify global ammonia (NH3) emissions over the period of 2008–2018 through an improved fast top-down method that incorporates IASI satellite observations and GEOS-Chem atmospheric chemical simulations. The top-down analysis finds a global total NH3 emission that is 30 % higher than the bottom-up estimate, largely reconciling a large discrepancy of more than a factor of two found in previous top-down studies using the same satellite data.