Vertical Resolution

Abstract

We have constructed multiple vertical grids to test the vertical resolution sensitivity of the ACME v0.0 model. Starting from the standard 30-level model (L30), we first create a 60-level model (L60) by doubling the resolution at all altitudes. Based on L60, we created L64a by adding 4 more layers in the PBL, and L64b by lowering the bottom layer so that the lower layer has a layer thickness of 20m. L47 and L50 are created based on L30, with doubling the resolution above/below 5km. Lastly, L72 is created based on L64b, with 8 additional layers on top of the model top of L64b by raising the model top to 0.1hPa. Several atmosphere-only simulations have been performed and the preliminary results suggest resolution sensitivity of model physics. Later in the year we will start testing the vertical resolution sensitivity of the new physics in the updated version of ACME. We will also explore the the validity of the cloud vertical overlap assumption with increasing vertical resolution and incorporate the cloud correlation length scale to adjust the overlap assumption.