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      https://www.ias.ac.in/article/fulltext/jess/125/01/0047-0064

    • Keywords

       

      WRF-CO2 model; Tsukuba tall tower; model–observation comparison; synoptic variation; diurnal cycle.

    • Abstract

       

      Simulation of carbon dioxide (CO2) at hourly/weekly intervals and fine vertical resolution at the continental or coastal sites is challenging because of coarse horizontal resolution of global transport models. Here the regional Weather Research and Forecasting (WRF) model coupled with atmospheric chemistry is adopted for simulating atmospheric CO2 (hereinafter WRF-CO2) in nonreactive chemical tracer mode. Model results at horizontal resolution of 27 × 27 km and 31 vertical levels are compared with hourly CO2 measurements from Tsukuba, Japan (36.05°N, 140.13°E) at tower heights of 25 and 200 m for the entire year 2002. Using the wind rose analysis, we find that the fossil fuel emission signal from the megacity Tokyo dominates the diurnal, synoptic and seasonal variations observed at Tsukuba. Contribution of terrestrial biosphere fluxes is of secondary importance for CO2 concentration variability. The phase of synoptic scale variability in CO2 at both heights are remarkably well simulated the observed data (correlation coefficient >0.70) for the entire year. The simulations of monthly mean diurnal cycles are in better agreement with the measurements at lower height compared to that at the upper height. The modelled vertical CO2 gradients are generally greater than the observed vertical gradient. Sensitivity studies show that the simulation of observed vertical gradient can be improved by increasing the number of vertical levels from 31 in the model WRF to 37 (4 below 200 m) and using the Mellor–Yamada–Janjic planetary boundary scheme. These results have large implications for improving transport model simulation of CO2 over the continental sites.

    • Author Affiliations

       

      Srabanti Ballav1 2 Prabir K Patra3 Yousuke Sawa4 Hidekazu Matsueda4 Ahoro Adachi4 Shigeru Onogi4 Masayuki Takigawa3 Utpal K De1

      1. School of Environmental Studies, Jadavpur University, Kolkata 700 032, India.
      2. Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263 002, Uttrakhand, India.
      3. Department of Environmental Geochemical Cycle Research, JAMSTEC, Yokohama 236-0001, Japan.
      4. Meteorological Research Institute, Tsukuba, Ibaraki 305-0052, Japan.
    • Dates

       
  • Journal of Earth System Science | News

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