Multi-scale predictability with a new coupled non-hydrostatic global model over the Arctic
Abstract
We propose to extend our atmospheric tests of a new atmospheric nonhydrostatic dy- namical core from the Model for Prediction Across Scales (MPAS) to a framework where MPAS is embedded within the Community Atmosphere Model (CAM) of the Community Earth System Model (CESM), on medium to long range weather prediction (week - months) focusing on the Arctic region. We subsequently refer to this fully- coupled atmosphere-ocean- land-sea ice modeling system as MPAS-CESM. MPAS is a fully compressible, nonhydrostatic, global model that allows for local re nement of the horizontal grid such that there is a smooth transition in resolution from the relatively coarse global mesh to ner mesh in regions of primary interest. Our preliminary results indicate that having a smooth transition in horizontal resolution reduce complications that typically arise from traditional downscaling and nesting approaches. Additionally, since MPAS does not employ a latitude-longitude grid, it does not require the use of polar ltering and will therefore exhibit uniform performance over polar regions. Given these new capabilities available with MPAS, and the earth- system couplings of CESM, MPAS-CESM is expected to make considerable improvements in numerical predictions at weekly to monthly time scales. We have implemented meshes for the atmospheric component that are locally re ned over the Arctic region which will be used for multi-scale CESM simulations in this study. We will use MPAS and the coupled MPAS-CESM to examine the evolution, dynamics and predictability of summer season Arctic surface pressure anomalies that we conjecture are associated with the dynamics of tropopause polar vortices (TPVs). The surface pressure anomalies correlate with the phase of the Arctic oscillation (AO) and the ow anomalies have a signi cant impact on sea ice movement and extent in the summer season. We have tested the ability of the atmospheric component of MPAS to simulate the evolution of TPVs in the summers of 2006 and 2007 that evinced anticyclonic and cyclonic sea-level pressure anomalies, respectively, for a variety of mesh con gurations and physical parameterizations. Our results emphasize the importance of resolving TPVs over the Arctic at ner scales and their dynamical linkages to to processes associated with developing surface cyclones at synoptic and sub-synoptic scales. We propose to examine the dynamics of these linkages and the ability of MPAS and MPAS-CESM to simulate the evolution of the coupled system. Speci cally, we will examine sensitivities in the evolution of the Arctic environment for the summers of 2006 and 2007 that evinced anticyclonic and cyclonic sea-level pressure anomalies, respectively. We will address questions that will include: How well can MPAS predict the evolution of the 2006 TPV in free-forecasting mode? Does sea ice evolve as with the physical expectations outlined above? Do we observe the appropriate AO signature in the MPAS-CESM simulations. We anticipate that the existing MPAS and CESM atmospheric physics may not be su cient, and we will test modi cations to model physics used in the Weather Research and Forecast (WRF) model.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512220
Entities
People
- Steven Cavallo
Organizations
- Office of Naval Research
- United States Navy
- University of Oklahoma