Specifying a zonally asymmetric ozone field in a dynamically-consistent manner: An inexpensive tool for studying interactions between chemistry and dynamics.
Abstract
A prescription for specifying zonally asymmetric ozone climatologies is developed for use as a forcing in climate model integrations. The prescription scales existing model tracers or active diagnostics to match certain zonal properties, which are specified in an ozone ancillary. The field is decomposed into a zonal mean and zonal anomaly, which are then scaled to match a specified zonal mean and zonal variance. The implementation of this into the Meteorological Office's Unified Model (version 8.4) is quicker than running full UKCA interactive chemistry by a factor of four. This tool can replicate historical ozone climatologies in free-running transient climate model integrations, and attempts to eliminate (and identify) biases introduced from zonally averaged specified ozone. This tool is used here to assess the influence of wintertime stratospheric ozone anomalies on climate by allowing imposed ozone anomalies to align with the stratospheric polar vortex, particularly in the Northern Hemisphere where the polar vortex may be largely azonal in nature. When Ertel's Potential Vorticity is used as the scaled tracer for the ozone field, ozone (and its zonal anomalies) can be synchronized with the polar vortex, creating a computationally-inexpensive alternative to specification onto equivalent latitude. Two ensembles are constructed, specifying various zonal ozone climatologies, both with and without the inclusion of zonal asymmetries. Without zonal asymmetries, the stratospheric ozone anomalies fail to have a significant influence on surface climate in the Northern Hemisphere. The difference in stratospheric state is characterized when zonal asymmetries are included, and it is determined if this dynamical coupling to the vortex is strong enough to allow for the polar stratospheric ozone anomalies to influence the troposphere and surface.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.A23I0341R
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 3337 Global climate models;
- ATMOSPHERIC PROCESSESDE: 3362 Stratosphere/troposphere interactions;
- ATMOSPHERIC PROCESSESDE: 3363 Stratospheric dynamics;
- ATMOSPHERIC PROCESSES