• HITOSHI MUKAI

      Articles written in Journal of Earth System Science

    • Assessment of spatio-temporal distribution of $\rm{CO}_{2}$ over greater Asia using the $\rm{WRF–CO}_{2}$ model

      SRABANTI BALLAV MANISH NAJA PRABIR K PATRA TOSHINOBU MACHIDA HITOSHI MUKAI

      More Details Abstract Fulltext PDF

      In-depth knowledge of global and regional carbon budget is required for effective policymaking to mitigate the global climate change. However, Asian carbon budget shows large uncertainty due to both lack of sufficient observations and detailed understanding of the existing $\rm{CO}_{2}$ observations. A regional air quality model ($\rm{WRF–CO}_{2}$) is set up for simulating atmospheric $\rm{CO}_{2}$ variations over the greater Asia region ($68–124^{0}\rm{E}$, $2^{0}\rm{S}–45^{0}\rm{N}$) for the period 2010–2012. The $\rm{WRF–CO}_{2}$ simulations are compared with observations from nine sites and a global Atmospheric Chemistry Transport Model (ACTM). The comparisons suggest $\rm{WRF–CO}_{2}$ simulation is able to capture large scale features in the observed variabilities, with varied ability at fine scales depending on representation of surface fluxes and meteorology around the observation sites. Analysis of $\rm{CO}_{2}$ signals from individual flux components suggests that ocean flux has least contribution to the $\rm{CO}_{2}$ variation (<10%). Four sites (Mt.Waliguan, Nainital, Cape Rama and Lulin) show dominance of biospheric flux over fossil flux to the $\rm{CO}_{2}$ variation (>80%). $\rm{CO}_{2}$ mixing ratios are found to be maximum in northern hemisphere (NH) winter over East Asia, while they are maximum in NH spring over Indian subcontinent. Observed peak-to-trough seasonal amplitude is lowest (4.5 ppm) for the site Bukit Koto Tabang, Indonesia and highest (29.5 ppm) for Shangdianzi in China. Statistical analysis from monthly mean $\rm{CO}_{2}$ time series shows that correlation coefficient and normalised standard deviation with observations, are generally equal or better for the $\rm{WRF–CO}_{2}$ than the coarser resolution ACTM. Study of synoptic scale $\rm{CO}_{2}$ variations shows that the $\rm{WRF–CO}_{2}$ is able to better resolve daytime signatures than those in the night. Year-to-year $\rm{CO}_{2}$ variations of seasonal cycle amplitude is highest ($\sim 5 \rm{ppm}$) at Nainital, India compared to all other sites.

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