Papers in plan and/or references, including information on who is proposing them, title, abstract, and the research topics and model output addressed.
____________________________________________________
(1) Assessing and Understanding the Impact of Stratospheric Dynamics and Variability on the Earth System
Gerber et al., Bulletin of the American Meteorological Society 2012
Recent advances in weather and climate research have demonstrated the role of the stratosphere in the Earth system across a wide range of time and spatial scales. Stratospheric ozone loss has been identified as a key driver of Southern Hemisphere tropospheric circulation trends, affecting ocean currents and carbon uptake, sea ice, and possibly even the Antarctic ice sheets. Likewise, stratospheric variability has been shown to have the potential to affect seasonal forecasts, connecting the tropics and midlatitudes and guiding storm track dynamics. The two-way interactions between the stratosphere and Earth system have inspired a multidisciplinary research forum, DynVar, to assess and understand the impact of stratospheric dynamics and variability on climate, and shaped two international modeling efforts. DynVar is an activity of the World Climate Research Program's (WRCP) Stratospheric Processes and Their Role in Climate (SPARC) project. It is anticipated that about 10 models of the Coupled Model Intercomparison Project 5 will include well resolved stratospheres, providing the first multimodel assessment of the Earth system coupled from stratopause to sea floor. The Stratosphere Historic Forecasting Project of WCRP’s Climate Variability and predictability (CLIVAR) project, will provide a multimodel set of seasonal hindcasts with stratosphere resolving models, revealing the impact of both stratospheric initial conditions and dynamics on intraseasonal prediction. These new data sets will provide an unprecedented opportunity to understand the role of the stratosphere in the natural and forced variability of the Earth system and determine whether incorporating knowledge of the upper atmosphere improves seasonal forecasts and climate prediction.
____________________________________________________
(2) Multi-model comparison of stratospheric climate, variability and change
Charlton-Perez et al
It is now widely accepted that changes in stratospheric climate can have important influences on the troposphere. The CMIP5 project will, for the first time, include a large number of fully coupled climate models with a high model top, which fully resolve the stratosphere. This will allow the community to understand and quantify the impact of the stratospheric climate change on the troposphere in unprecedented detail. A key step is to assess the performance of the new high-top models in the stratosphere and compare them to standard low-top climate models. This study provides a first overview of the performance of the high-top models. Process-based diagnostics, previously used to characterize the stratosphere in multi-model ensembles are applied to the CMIP5 model set and a comparison of the performance of the high and low-top subsets of models is made. Finally, a broad scale assessment of the models reproduction of past climate change in the stratosphere is made and compared to their predictions for future climate.
Research Topic(s): Sudden Stratospheric Warming Events; Extratropical Wave Coupling; QBO and Tropical Waves; Annular Modes and Stratospheric Memory;
Model-outputs: CMIP5
____________________________________________________
(3) Surface Climate, Variability and Change in the CMIP5 simulations: Role of Stratospheric Variability
Manzini, Scaife, Charlton-Perez et al
There is mounting and multiple evidence from modeling works and observational analyses that dynamical variability in the stratosphere has an important impact on tropospheric climate. The aim is to systematically evaluate the impact of a dynamical stratosphere on surface climate, variability and change by comparing standard diagnostics computed from the high top (model lid above the stratopause) and low top (model lid in the mid-stratosphere) multi-model ensembles available within WCRP’s CMIP5. This multi-model approach is made possible for the fist time due to the large number of the CMIP5 simulations which will be carried out with “high top” climate models (e.g., 3-D coupled atmosphere ocean sea-ice models, specifically designed to simulate stratospheric dynamics, it is expected about 10 of such models within the CMIP5 set). The focus is on middle-high latitude surface climate, intra-seasonal and inter-annual variability diagnosed by meteorological quantities including MSLP, 2m-T, precipitation and measures of storm track activity. The change in climate and variability will be analyzed by comparing the last decades of the 20th and 21st centuries. It is expected that detailed analysis will be carried out elsewhere; the aim here is a synthesis of the robustness of coupling between the stratosphere and troposphere evident in the latest generation of coupled climate models. For the interpretation of the high / low top model inter-comparison, it will be crucial to have information on the performance of the high top and low top models in the stratosphere. This part will refer and make use of the results of the synthesis paper aimed at evaluating the model performance in stratospheric climate and variability. Here, a crucial point will be to find if there is a relationship between the model performance in the stratosphere and the impact of stratospheric variability on future-past tropspheric climate changes.
Research Topic(s): Surface Climate, Variability and Change; Sudden Stratospheric Warming; Extratropical Wave Coupling; Annular Modes and Stratospheric Memory
Model-outputs: CMIP5
____________________________________________________