Impact of the Inter-annual Variability in CO2 Growth Rate from Atmospheric Transport and Contribution from Latitudinal Partition
Abstract
A comprehensive analysis was conducted to quantitatively investigate the impact of major CO2 components on the inter-annual variability in the atmospheric CO2, and the contribution of individual latitude bands to the CO2 growth rate as well. A series of numerical experiments were performed with a three-dimensional atmospheric tracer transport model (NIES/FCGCC). Model simulations were driven with NCAR/NCEP reanalysis wind field. Two types of CO2 fluxes were applied to force the model simulations: (1) the first one constitutes the major CO2 reservoirs, including terrestrial biospheric fluxes obtained by Biome BGC model, monthly fossil fuel emission and oceanic fluxes (no inter-annual variation) (2) The second type is global CO2 fluxes deduced using TDI (time-dependent-inverse) analysis from atmospheric measurements (Global View CO2, 2005), which is partitioned into fluxes for five latitude bands. Results indicate that fluxes in the tropical terrestrial biosphere contributes the most to the inter-annual variability in the atmospheric CO2 concentration on global scale (~65%); the atmospheric circulation accounts for partly of the CO2 growth rate in the northern hemisphere and the tropic regions (~30%). The observed low CO2 increase in the early 1990s is suggested to be caused by enhanced CO2 uptake in the northern mid- latitudes and the tropical regions. Additionally, we also found that a fraction of the CO2 growth rate can be ascribed to regional CO2 fluxes, i.e., CO2 fluxes in northern mid and high latitudes account for a large fraction of CO2 fluctuation in northern hemisphere; while fluxes in southern mid-to-high latitudes contribute partly to CO2 variations in the southern hemisphere. We also investigated the relationship between the CO2 anomaly and climate change index, and found that the inter-annual CO2 variability is closely related to climate anomalies like ENSO events,NAO, PNAO and Pacific Decadal Oscillation. The result suggests that accurate and vastly covered observation network are indispensable for improving our quantitative investigation of CO2 fluxes, especially for estimation of changes of regional CO2 sources and sinks.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.U43D..01Z
- Keywords:
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- 0368 Troposphere: constituent transport and chemistry