Belikov, D. A. and Maksyutov, S. and Sherlock, V. and Aoki, S. and Deutscher, N. M. and Dohe, S. and Griffith, D. and Kyro, E. and Morino, I. and Nakazawa, T. and Notholt, J. and Rettinger, M. and Schneider, M. and Sussmann, R. and Toon, G. C. and Wennberg, P. O. and Wunch, D. (2013) Simulations of column-averaged CO_2 and CH_4 using the NIES TM with a hybrid sigma-isentropic (σ-θ) vertical coordinate. Atmospheric Chemistry and Physics, 13 (4). pp. 1713-1732. ISSN 1680-7316. http://resolver.caltech.edu/CaltechAUTHORS:20130410-071421073
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We have developed an improved version of the National Institute for Environmental Studies (NIES) three-dimensional chemical transport model (TM) designed for accurate tracer transport simulations in the stratosphere, using a hybrid sigma-isentropic (σ-θ) vertical coordinate that employs both terrain-following and isentropic parts switched smoothly around the tropopause. The air-ascending rate was derived from the effective heating rate and was used to simulate vertical motion in the isentropic part of the grid (above level 350 K), which was adjusted to fit to the observed age of the air in the stratosphere. Multi-annual simulations were conducted using the NIES TM to evaluate vertical profiles and dry-air column-averaged mole fractions of CO_2 and CH_4. Comparisons with balloon-borne observations over Sanriku (Japan) in 2000–2007 revealed that the tracer transport simulations in the upper troposphere and lower stratosphere are performed with accuracies of ~5% for CH_4 and SF_6, and ~1% for CO_2 compared with the observed volume-mixing ratios. The simulated column-averaged dry air mole fractions of atmospheric carbon dioxide (XCO_2) and methane (XCH_4) were evaluated against daily ground-based high-resolution Fourier Transform Spectrometer (FTS) observations measured at twelve sites of the Total Carbon Column Observing Network (TCCON) (Bialystok, Bremen, Darwin, Garmisch, Izaña, Lamont, Lauder, Orleans, Park Falls, Sodankylä, Tsukuba, and Wollongong) between January 2009 and January 2011. The comparison shows the model's ability to reproduce the site-dependent seasonal cycles as observed by TCCON, with correlation coefficients typically on the order 0.8–0.9 and 0.4–0.8 for XCO_2 and XCH_4, respectively, and mean model biases of ±0.2% and ±0.5%, excluding Sodankylä, where strong biases are found. The ability of the model to capture the tracer total column mole fractions is strongly dependent on the model's ability to reproduce seasonal variations in tracer concentrations in the planetary boundary layer (PBL). We found a marked difference in the model's ability to reproduce near-surface concentrations at sites located some distance from multiple emission sources and where high emissions play a notable role in the tracer's budget. Comparisons with aircraft observations over Surgut (West Siberia), in an area with high emissions of methane from wetlands, show contrasting model performance in the PBL and in the free troposphere. Thus, the PBL is another critical region for simulating the tracer total column mole fractions.
|Additional Information:||© 2013 Author(s). Published by Copernicus Publications on behalf of the European Geosciences Union. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 15 November 2011. Published in Atmos. Chem. Phys. Discuss.: 23 March 2012. Revised: 5 January 2013. Accepted: 18 January 2013. Published: 15 February 2013. We thank T. Machida for aircraft observations of CH4 over Surgut (Russia); and A. E. Andrews, T. M. Hall, and D. W. Waugh for providing observation data of the mean age of air in the stratosphere. We also thank P. K. Patra and the TransCom-CH4 and CONTRAIL TMI communities for model setups, initial profiles, and emission fluxes used in the tracer transport simulation. We also thank S. Oshchepkov for insightful discussions and suggestions regarding the manuscript. The meteorological datasets used for this study were provided by the cooperative research project of the JRA-25/JCDAS long-term reanalysis by the Japan Meteorological Agency (JMA) and the Central Research Institute of Electric Power Industry (CRIEPI). We also thank GLOBALVIEWCO2/CH4 authors. For calculations, we used the computational resources of the NIES supercomputer system (NEC SX-8R/128M16). TCCON data were obtained from the TCCON Data Archive, operated by the California Institute of Technology from the website at http://tccon.ipac.caltech.edu/. US funding for TCCON comes from NASA’s Terrestrial Ecology Program, grant number NNX11AG01G, the Orbiting Carbon Observatory Program, the Atmospheric CO2 Observations from Space (ACOS) Program and the DOE/ARM Program. The Darwin TCCON site was built at Caltech with funding from the OCO project, and is operated by the University of Wollongong, with travel funds for maintenance and equipment costs funded by the OCO-2 project. We acknowledge funding to support Darwin and Wollongong from the Australian Research Council, Projects LE0669470, DP0879468, DP110103118 and LP0562346. Lauder TCCON measurements are funded by New Zealand Foundation of Research Science and Technology contracts C01X0204 and CO1X0406. We acknowledge financial support of the Bialystok and Orleans TCCON sites from the Senate of Bremen and EU projects IMECC and GEOmon, as well as maintenance and logistical work provided by AeroMeteo Service (Bialystok) and the RAMCES team at LSCE (Gif-sur-Yvette, France) and additional operational funding from the National Institute for Environmental Studies (NIES, Japan). Edited by: P. Monks|
|Official Citation:||Belikov, D. A., Maksyutov, S., Sherlock, V., Aoki, S., Deutscher, N. M., Dohe, S., Griffith, D., Kyro, E., Morino, I., Nakazawa, T., Notholt, J., Rettinger, M., Schneider, M., Sussmann, R., Toon, G. C., Wennberg, P. O., and Wunch, D.: Simulations of column-averaged CO2 and CH4 using the NIES TM with a hybrid sigma-isentropic (σ-θ) vertical coordinate, Atmos. Chem. Phys., 13, 1713-1732, doi:10.5194/acp-13-1713-2013, 2013.|
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|Deposited By:||Ruth Sustaita|
|Deposited On:||10 Apr 2013 14:54|
|Last Modified:||10 Apr 2013 16:20|
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