Winter crop CO2 uptake inferred from CONTRAIL measurements over Delhi, India
- 著者
- Umezawa T., Niwa Y., Sawa Y., Machida T., Matsueda H.
- 雑誌名
- Geophys. Res. Lett., 43
- DOI
- 10.1002/2016GL070939
- 概要
-
Recent studies have shown the impact of expanding agricultural activities on atmospheric CO2 variations and the global carbon cycle. In this study, we show clear evidence of the measureable impact of Indian wintertime crops (mainly wheat) on the regional carbon budget using high-frequency atmospheric CO2 measurements by Comprehensive Observation Network for Trace gases by Airliners (CONTRAIL) over Delhi; this phenomenon is not detected by the existing network of surface CO2 sites. While a general increase in the vertical profiles of CO2 toward the ground in the boundary layer was observed throughout December–April, we frequently observed sharp decreases below 2 km during January–March. Seasonal circulations during these 3 months indicated influences from neighboring croplands (with patchy urban areas) located upwind. We conclude that the observed CO2 decrease is attributable to active uptake by the crops grown in winter and that the uptake exceeds in magnitude the urban CO2 emissions from the Delhi metropolitan area.