[A-AS10] General Meteorology

[AAS10-06] Simulated climatologies of Northern Hemisphere blocking and storm tracks in an AGCM

*Akira Yamazaki¹, Yuya Baba¹, Ayako Yamamoto^2,1, Patrick Martineau¹, Masami Nonaka¹ (1.Application Laboratory, Japan Agency for Marine-Earth Science and Technology, 2.J. F. Oberlin University)

Keywords:blocking, storm tracks, Atmospheric GCM

Climatologies of Northern Hemisphere Pacific blocking (PB) and Atlantic blocking (AB) in relation to storm tracks are examined with a conventional AGCM called AFES (with hydrostatic dynamical core and convection, radiation, gravity wave, turbulent-process, and land-process schemes). The model is prescribed with realistically varying sea surface temperature, i.e., AMIP-type simulations, using 7 different horizontal resolutions ranging from 300-km to 25-km and two different convection schemes. As such, a total of 14 experiments are conducted by combining each convection scheme and resolution, from January 1982 to December 2022. For detection of blocking, the PV anomaly-based method by Schwierz et al. (2004) with a 5-day duration threshold is utilized.
It is found that the PB and AB frequencies and storm track intensities are adequately simulated with a horizontal resolution of around 100-km, which get increasingly overestimated with finer resolution in both winter and summer seasons. This overestimation of PB and AB frequencies are linked to increase in storm track intensities with resolution over both the Pacific and Atlantic.