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Topics in 2019



Interannual variations of CO in the upper troposphere

We analyzed temporal variations of carbon monoxide (CO) in the upper troposphere from 30°N to 30°S observed using instruments aboard commercial airliner flights between Japan and Australia over the period 1993-2016. Here we focused on the CO variations in the Southern Hemisphere (SH) that showed a unique seasonal cycle with an increased CO around October-November every year. The seasonal CO peaks in the SH showed significant interannual variability (IAV), and are notably enhanced in strong El Niño years, especially 1997. The CO enhancements are proportionally associated with CO emissions from Indonesian fires, when compared to the Global Fire Emissions Database (GFED). The IAV of the CO peak anomalies relative to the mean seasonal cycle was assessed by a statistical regression model that uses a combination of multiple climate indices and their interaction terms. We found that over 80% of the CO IAV observed in the upper troposphere could be explained by the model. The largest anomaly in 1997 showed a different CO-climate relationship than the other periods, which could be due to amplification during synchronized climate modes, or include additional influence from other factors such as human activities.

Temporal variations, 1994 to 2016, of (a) detrended CO (ΔCO) for 3 latitudinal bands of 10°S-15°S, 15°S-20°S, and 20°S-25°S, (b) monthly averages of the ΔCO from the three bands between 10°S and 25°S showing positive ΔCO in black and negative ΔCO in grey with the climatological seasonal cycle (dashed line), (c) monthly CO emissions (Tg CO month-1) for the equatorial Asia (EQAS) region estimated from the Global Fire Emissions Database (GFED4.1s) for the period 1997-2016 (van der Werf et al., 2017).

Temporal variations for 1994-2016, of (a) monthly averaged CO anomalies (10°S-25°S) with MOPITT XCO anomalies, and (b-e) four climate indices, showing positive anomalies in black and negative anomalies in grey. MEI = Multivariate ENSO Index; DMI = Dipole Mode Index; TSA = Tropical South Atlantic; SAM = Southern Annular Mode.

Reference


CONTRAIL Data Release: Trace gas data from ASE/MSE

The CONTRAIL trace gas data measured from ASE/MSE are now available via the Global Environmental Database of Center for Global Environmental Studies, National Institute for Environmental Studies. For data download, visit the GED website for Pacific flights and Eurasia flights.


CONTRAIL team awarded the 1st Japan Open Innovation Prize

The CONTRAIL team awarded the Minister of the Environment Award of the 1st Japan Open Innovation Prize. Our long-term observational achievements by collaboration of different organizations and contributions to international environmental actions were highly evaluated.


A group photo of the CONTRAIL team at the ceremony.


Minister of the Environment met the CONTRAIL team

The CONTRAIL team visited Minister of the Environment Yoshiaki Harada.


A group photo with the Minister of the Environment Yoshiaki Harada (right).