Trends in global tropospheric ozone inferred from a composite record of TOMS/OMI/MLS/OMPS satellite measurements and the MERRA-2 GMI simulation
2018
Abstract. Past studies have suggested that ozone in the troposphere has
increased globally throughout much of the 20th century due to increases in
anthropogenic emissions and transport. We show, by combining satellite
measurements with a chemical transport model, that during the last four
decades tropospheric ozone does indeed indicate increases that are global in
nature, yet still highly regional. Satellite ozone measurements from
Nimbus-7 and Earth Probe Total Ozone Mapping Spectrometer (TOMS) are merged
with ozone measurements from the Aura Ozone Monitoring Instrument/Microwave Limb
Sounder (OMI/MLS) to determine trends in tropospheric ozone for 1979–2016.
Both TOMS (1979–2005) and OMI/MLS (2005–2016) depict large increases in
tropospheric ozone from the Near East to India and East Asia and further
eastward over the Pacific Ocean. The 38-year merged satellite record shows
total net change over this region of about +6 to +7 Dobson units (DU)
(i.e., ∼15 %–20 % of average background ozone), with the
largest increase ( ∼4 DU) occurring during the 2005–2016 Aura
period. The Global Modeling Initiative (GMI) chemical transport model with
time-varying emissions is used to aid in the interpretation of tropospheric
ozone trends for 1980–2016. The GMI simulation for the combined record also
depicts the greatest increases of +6 to +7 DU over India and East Asia, very
similar to the satellite measurements. In regions of significant increases
in tropospheric column ozone (TCO) the trends are a factor of 2–2.5 larger
for the Aura record when compared to the earlier TOMS record; for India and East Asia the trends in TCO for both GMI and satellite measurements are
∼ + 3 DU decade −1 or greater during 2005–2016 compared
to about +1.2 to +1.4 DU decade −1 for 1979–2005. The GMI simulation
and satellite data also reveal a tropospheric ozone increases in
∼ + 4 to +5 DU for the 38-year record over central Africa
and the tropical Atlantic Ocean. Both the GMI simulation and
satellite-measured tropospheric ozone during the latter Aura time period
show increases of ∼ + 3 DU decade −1 over the N Atlantic
and NE Pacific.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
46
References
49
Citations
NaN
KQI