Preprints
https://doi.org/10.5194/acp-2020-1128
https://doi.org/10.5194/acp-2020-1128

  02 Dec 2020

02 Dec 2020

Review status: a revised version of this preprint was accepted for the journal ACP and is expected to appear here in due course.

Analysis of CO2 spatiotemporal variations in China using tower data and a weather-biosphere-online-coupled model, WRF-VPRM

Xinyi Dong1,2, Man Yue1,2, Yujun Jiang3,4, Xiao-Ming Hu5, Qianli Ma4, Jingjiao Pu3, and Guangqiang Zhou6 Xinyi Dong et al.
  • 1School of Atmospheric Science, Nanjing University, Nanjing, 210023, China
  • 2Joint International Research Laboratory of Atmospheric and Earth System Sciences & Institute for Climate and Global Change Research, Nanjing University, Nanjing, 210023, China
  • 3Zhejiang Meteorological Science Institute, Hangzhou 310008, China
  • 4Zhejiang Lin'an Atmospheric Background National Observation and Research Station, Hangzhou 311307, China
  • 5Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma, 73072, USA
  • 6Shanghai Key Laboratory of Health and Meteorology, Shanghai Meteorological Service, Shanghai, 200135, China

Abstract. Dynamics of CO2 has received considerable attention in the literature, yet significant uncertainties remain within the estimates of contribution from terrestrial flux and the influence of atmospheric mixing. In this study we apply the Weather Research and Forecasting model coupled with Vegetation Photosynthesis and Respiration Model (WRF-VPRM) in China to characterize CO2 dynamics with tower data collected at a background site Lin’an (30.30° N, 119.75° E). The online coupled weather-biosphere WRF-VPRM simulations are able to simulate biosphere processes (photosynthetic uptake and ecosystem respiration) and meteorology in one coordinate system. Simulations are conducted for three years (2016–2018) with fine grid resolution (20 km) to detail the spatiotemporal variations of CO2 fluxes and concentrations. This is the first attempt to apply the weather-biosphere model for a multi-year simulation with integrated data from a satellite product, flask samplings, and tower measurements to diagnose the dynamics of CO2 in China. We find that the spatial distribution of CO2 is determined by anthropogenic emissions, while its seasonality (with maximum concentrations in April 15 ppmv higher than minimums in August) is dominated by terrestrial flux and background CO2. Observations and simulations reveal a consistent increasing trend in column-averaged CO2 (XCO2) of 0.6 %/yr resulting from anthropogenic emission growth and biosphere uptake. WRF-VPRM successfully reproduces ground-based measurements of surface CO2 concentration with mean bias of −0.79 ppmv (−0.20 %) and satellite derived XCO2 with mean bias of 0.76 ppmv (0.19 %). The model-simulated seasonality is also consistent with observations, with correlation coefficients of 0.90 and 0.89 for ground-based measurements and Orbiting Carbon Observatory-2 (OCO-2) satellite data, respectively. However, evaluation against Lin'an tower data reveals uncertainty within the model for simulating the intensity and diurnal variation of terrestrial flux, which contributes to overestimation by ~5.35 ppmv (1.26 %). Lin'an tower observations also reveal a strong correlation (−0.85) between vertical CO2 and temperature gradients, suggesting a significant influence of boundary layer thermal structure on the accumulation and depletion of atmospheric CO2.

Xinyi Dong et al.

 
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Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Xinyi Dong et al.

Xinyi Dong et al.

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Short summary
Dynamics of CO2 received considerable attention in the literature yet significant uncertainties remain. We applied an online coupled weather-biosphere model to simulate biosphere processes and meteorology simultaneously to characterize CO2 dynamics in China. We found anthropogenic emission was more influential in upper air and biosphere flux played a more important role on surface CO2, and a significant influence of boundary layer thermal structure on the accumulation and depletion of CO2.
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