Title: Evaluation of tropical channel refinement using MPAS‐A aquaplanet simulations

Abstract

Climate models with variable-resolution grids offer a computationally less expensive way to provide more detailed information at regional scales and increased accuracy for processes that cannot be resolved by a coarser grid. This study uses the Model for Prediction Across Scales–Atmosphere (MPAS22A), consisting of a nonhydrostatic dynamical core and a subset of Advanced Research Weather Research and Forecasting (ARW-WRF) model atmospheric physics that have been modified to include the Community Atmosphere Model version 5 (CAM5) cloud fraction parameterization, to investigate the potential benefits of using increased resolution in an tropical channel. The simulations are performed with an idealized aquaplanet configuration using two quasi-uniform grids, with 30 km and 240 km grid spacing, and two variable-resolution grids spanning the same grid spacing range; one with a narrow (20°S–20°N) and one with a wide (30°S–30°N) tropical channel refinement. Results show that increasing resolution in the tropics impacts both the tropical and extratropical circulation. Compared to the quasi-uniform coarse grid, the narrow-channel simulation exhibits stronger updrafts in the Ferrel cell as well as in the middle of the upward branch of the Hadley cell. The wider tropical channel has a closer correspondence to the 30 km quasi-uniform simulation. However, the total atmospheric polewardmore » energy transports are similar in all simulations. The largest differences are in the low-level cloudiness. The refined channel simulations show improved tropical and extratropical precipitation relative to the global 240 km simulation when compared to the global 30 km simulation. All simulations have a single ITCZ. Furthermore, the relatively small differences in mean global and tropical precipitation rates among the simulations are a promising result, and the evidence points to the tropical channel being an effective method for avoiding the extraneous numerical artifacts seen in earlier studies that only refined portion of the tropics.« less

Authors:

Martini, Matus N. ^[1]; Gustafson, Jr., William I. ^[2]; O'Brien, Travis A. ^[3]; Ma, Po‐Lun ^[2]

---

+ Show Author Affiliations

1. Atmospheric Sciences and Global Change Division Pacific Northwest National Laboratory Richland Washington USA, Now at Naval Research Laboratory Monterey California USA
2. Atmospheric Sciences and Global Change Division Pacific Northwest National Laboratory Richland Washington USA
3. Lawrence Berkeley National Laboratory Berkeley California USA

Publication Date:

Sun Sep 13 00:00:00 EDT 2015

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1214753

Alternate Identifier(s):

OSTI ID: 1229973; OSTI ID: 1785816

Report Number(s):

PNNL-SA-109622
Journal ID: ISSN 1942-2466

Grant/Contract Number:  

AC02-05CH11231; AC05-76RL01830

Resource Type:

Published Article

Journal Name:

Journal of Advances in Modeling Earth Systems

Additional Journal Information:

Journal Name: Journal of Advances in Modeling Earth Systems Journal Volume: 7 Journal Issue: 3; Journal ID: ISSN 1942-2466

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; tropical; MPAS-A; aquaplanet; simulations; climate models