Winter crop CO2 uptake inferred from CONTRAIL CO2 measurements over Delhi, India
Abstract
CONTRAIL is an ongoing project that measures atmospheric trace gases onboard aircraft of Japan Airlines. Atmospheric CO2 concentration is analyzed using Continuous CO2 Measuring Equipment (CME) during intercontinental flights. Since 2005, we have obtained >7 millions of data points of CO2 concentration along level-flight and ascent/descent tracks of >12 thousands flights with extensive coverage of the Asia-Pacific region. In this study, we analyze 787 vertical profiles of CO2 over Delhi, India. The surrounding area is mainly covered by irrigated croplands with patchy urban areas. We observed a general increase of CO2 toward the ground in the boundary layer throughout December-April due to urban CO2 emissions from the Delhi metropolitan area. In January-March, however, we frequently observed sharp decreases of CO2 below 2 km, indicating the existence of local CO2 sinks in this season. We calculated enhancement/depletion of CO2 amount in the boundary layer, and found clear depletion in February-March, coincident with the growing season of the winter crops (mainly wheat) in the region. It is also inferred that the crop uptake may exceed in magnitude the urban anthropogenic emissions from the Delhi area, indicating significance of agricultural CO2 fluxes in the regional carbon budget. Due to the winter crop uptake, CO2 concentration over Delhi shows no increasing/decreasing temporal trends during January-March when that at baseline stations at similar latitudes in the northern hemisphere increases steadily. This suggests that the CONTRAIL measurements capture local to regional flux signals that are not well resolved by the existing observation network.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.B33C0608U
- Keywords:
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- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSESDE: 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0469 Nitrogen cycling;
- BIOGEOSCIENCES