Open AccessInverse estimation of NOx emissions over China and India 2005–2016: contrasting recent trends and future perspectives
Author(s) -
Syuichi Itahashi,
Keiya Yumimoto,
J. Kurokawa,
Yu Morino,
Tatsuya Nagashima,
Kazuyuki Miyazaki,
T. Mäki,
Toshimasa Ohara
Publication year - 2019
Publication title -
environmental research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.37
H-Index - 124
ISSN - 1748-9326
DOI - 10.1088/1748-9326/ab4d7f
Subject(s) - inversion (geology) , china , environmental science , emission inventory , greenhouse gas , satellite , constraint (computer aided design) , estimation , chemical transport model , atmospheric sciences , meteorology , climatology , geography , mathematics , economics , geology , air quality index , physics , paleontology , oceanography , geometry , archaeology , management , structural basin , astronomy
Bottom-up emission inventories can provide valuable information for understanding emission status and are needed as input datasets to drive chemical transport models. However, this type of inventory has the disadvantage of taking several years to be compiled because it relies on a statistical dataset. Top-down approaches use satellite data as a constraint and overcome this disadvantage. We have developed an immediate inversion system to estimate anthropogenic NO x emissions with NO 2 column density constrained by satellite observations. The proposed method allows quick emission updates and considers model and observation errors by applying linear unbiased optimum estimations. We used this inversion system to estimate the variation of anthropogenic NO x emissions from China and India from 2005 to 2016. On the one hand, NO x emissions from China increased, reaching a peak in 2011 with 29.5 Tg yr −1 , and subsequently decreased to 25.2 Tg yr −1 in 2016. On the other hand, NO x emissions from India showed a continuous increase from 2005 to 2016, reaching 13.9 Tg yr −1 in 2016. These opposing trends from 2011 to 2016 were −0.83 and +0.76 Tg yr −1 over China and India, respectively, and correspond to strictly regulated and unregulated future scenarios. Assuming these trends continue after 2016, we expect NO x emissions from China and India will be similar in 2023, with India becoming the world’s largest NO x emissions source in 2024.