89th American Meteorological Society Annual Meeting

Monday, 12 January 2009: 1:30 PM
Resolution dependency of tropical convection in Goddard Cumulus Ensemble model
Room 129A (Phoenix Convention Center)
Ildae Choi, Seoul National University, Seoul, South Korea; and W. K. Tao and I. S. Kang
Using a 2-dimensional or 3-dimensional atmospheric model that is capable of explicitly resolving cloud process (i.e., Cloud Resolving Model), this study explores the propagation phenomena of tropical storms in large domain. The Goddard Cumulus Ensemble (GCE) model is simulated in 1km, 5km and 20km horizontal resolution with prescribed sea surface temperature, and constant radiative cooling effect. The TOGA COARE sounding data from GCSS WG4 is used to the initial condition in this study.

Many previous CRM studies showed that the tropical individual storm propagate westward and the cloud clusters move eastward in large domain cases. The results were implemented generally in the radiative-convective equilibrium simulation. This study basically follows the main concept of former studies. Aside from this, when we change the horizontal resolution of GCE model, we will expect the difference of phase speed in each tropical storm making specific propagating patterns. That result is proved in the research when we increase the horizontal domain in CRM, the precipitation time is delayed.

The propagation pattern of 5km resolution result in 10000km domain is similar to the previous studies though this result has coarser resolution than common CRM. The CRM resolves realistic clouds well, but this model is used generally in regional model because of its big simulation time. So when we understand the difference of characteristics at the coarser resolution case, we can apply this good performance of CRM physics to global climate model (GCM) more easily. This new type of GCM will be expected to have good performance in tropical convection or other cases.

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