In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 9 ( 2018-05-16), p. 6867-6885
Abstract:
Abstract. In this study, we describe the recent changes in
the tropospheric ozone (O3) columns measured by the Infrared Atmospheric
Sounding Interferometer (IASI), onboard the Metop satellite, during the first 9
years of operation (January 2008 to May 2017). Using appropriate
multivariate regression methods, we differentiate significant linear trends
from other sources of O3 variations captured by IASI. The geographical
patterns of the adjusted O3 trends are provided and discussed on the
global scale. Given the large contribution of the natural variability in
comparison with that of the trend (25–85 % vs. 15–50 %,
respectively) to the total O3 variations, we estimate that additional
years of IASI measurements are generally required to detect the estimated
O3 trends with high precision. Globally, additional 6 months to
6 years of measurements, depending on the regions and the seasons, are needed
to detect a trend of |5| DU decade−1. An exception is interestingly
found during summer at mid- and high latitudes of the Northern Hemisphere (NH;
∼ 40 to ∼ 75∘ N), where the large absolute fitted trend values
(∼ |0.5| DU yr−1 on average) combined with the small model
residuals (∼ 10 %) allow for detection of a band-like pattern of
significant negative trends. Despite no consensus in terms of
tropospheric O3 trends having been reached from the available
independent datasets (UV or IR satellites, O3 sondes, aircrafts,
ground-based measurements, etc.) for the reasons that are discussed in the
text, this finding is consistent with the reported decrease in O3
precursor emissions in recent years, especially in Europe and USA. The
influence of continental pollution on that latitudinal band is further
investigated and supported by the analysis of the O3–CO relationship
(in terms of correlation coefficient, regression slope and covariance) that
we found to be the strongest at northern midlatitudes in summer.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-6867-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
