270 A Revised Convective Eddy Diffusion Scheme in the Korea Integrated Model

Wednesday, 11 July 2018
Regency A/B/C (Hyatt Regency Vancouver)
Seung-Bu Park, Korea Institute of Atmospheric Prediction Systems, SEOUL, Korea, Republic of (South)

The shallow convection scheme in the Korea Integrated Model (KIM), based on a turbulent eddy diffusion approach, is revised and tested. While subcloud-layer heat and moisture are diffused upward through the whole grid in the previous scheme, convective eddy diffusion is allowed only through narrow cloudy fraction in the revised scheme. The cloudy fraction of each grid is estimated using a function of grid-mean-vertical-velocity and other variables. The eddy diffusivity is now calculated using the instability length scale and the velocity scale representing latent heat release. The cloudy-fraction-function and eddy diffusivity are being evaluated using large-eddy simulation data. The upward-diffused heat and moisture change temperature and humidity profiles, respectively, but only in the narrow cloudy fraction. While the upward-diffused moisture does not easily condense and subgrid condensates at 850 hPa are underestimated in the previous scheme, more moisture in the updated temperature and humidity environment are condensed and the bias of liquid water mixing ratio decreases after implementing the revised scheme. More details of the revised scheme and results will be presented at the conference.
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