scholarly journals Improved representation of atmospheric dynamics in CMIP6 models removes climate sensitivity dependence on Hadley cell climatological extent

2021 ◽  
Author(s):  
Bithi De ◽  
George Tselioudis ◽  
Lorenzo M. Polvani
Keyword(s):  
Climate Sensitivity ◽  
Atmospheric Dynamics ◽  
Hadley Cell

scholarly journals CMIP5 models' shortwave cloud radiative response and climate sensitivity linked to the climatological Hadley cell extent

2017 ◽  
Vol 44 (11) ◽  
pp. 5739-5748 ◽  
Author(s):  
Bernard R. Lipat ◽  
George Tselioudis ◽  
Kevin M. Grise ◽  
Lorenzo M. Polvani
Keyword(s):  
Climate Sensitivity ◽  
Hadley Cell ◽  
Cmip5 Models

Quantifying the Summertime Response of the Austral Jet Stream and Hadley Cell to Stratospheric Ozone and Greenhouse Gases

2014 ◽  
Vol 27 (14) ◽  
pp. 5538-5559 ◽  
Author(s):  
Edwin P. Gerber ◽  
Seok-Woo Son
Keyword(s):  
Greenhouse Gases ◽  
Climate Sensitivity ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Coupled Model ◽  
Hadley Cell ◽  
Dynamical Response ◽  
Jet Stream ◽  
Temperature Trends ◽  
The Impact

Abstract The impact of anthropogenic forcing on the summertime austral circulation is assessed across three climate model datasets: the Chemistry–Climate Model Validation activity 2 and phases 3 and 5 of the Coupled Model Intercomparison Project. Changes in stratospheric ozone and greenhouse gases impact the Southern Hemisphere in this season, and a simple framework based on temperature trends in the lower polar stratosphere and upper tropical troposphere is developed to separate their effects. It suggests that shifts in the jet stream and Hadley cell are driven by changes in the upper-troposphere–lower-stratosphere temperature gradient. The mean response is comparable in the three datasets; ozone has chiefly caused the poleward shift observed in recent decades, while ozone and greenhouse gases largely offset each other in the future. The multimodel mean perspective, however, masks considerable spread in individual models’ circulation projections. Spread resulting from differences in temperature trends is separated from differences in the circulation response to a given temperature change; both contribute equally to uncertainty in future circulation trends. Spread in temperature trends is most associated with differences in polar stratospheric temperatures, and could be narrowed by reducing uncertainty in future ozone changes. Differences in tropical temperatures are also important, and arise from both uncertainty in future emissions and differences in models’ climate sensitivity. Differences in climate sensitivity, however, only matter significantly in a high emissions future. Even if temperature trends were known, however, differences in the dynamical response to temperature changes must be addressed to substantially narrow spread in circulation projections.

A Test of Emergent Constraints on Cloud Feedback and Climate Sensitivity Using a Calibrated Single-Model Ensemble

2018 ◽  
Vol 31 (18) ◽  
pp. 7515-7532 ◽  
Author(s):  
Benjamin M. Wagman ◽  
Charles S. Jackson
Keyword(s):  
Relative Humidity ◽  
Climate Sensitivity ◽  
Threshold Value ◽  
Cloud Feedback ◽  
Hadley Cell ◽  
Model Ensemble ◽  
Single Model ◽  
Community Atmosphere Model ◽  
Emergent Constraints ◽  
Out Of Sample

A calibrated single-model ensemble (SME) derived from the NCAR Community Atmosphere Model, version 3.1, is used to test two hypothesized emergent constraints on cloud feedback and equilibrium climate sensitivity (ECS). The Fasullo and Trenberth relative humidity (RH) metric and the Sherwood et al. lower-tropospheric mixing (LTMI) metric are computed for the present-day climate of the SME, and the relationships between the metrics, ECS, and cloud and other climate feedbacks are examined. The tropical convergence zone relative humidity (RH M) and the parameterized lower-tropospheric mixing (LTMI S) are positively correlated to ECS, and each is associated with a different spatial pattern of tropical shortwave cloud feedback in the SME. However, neither of those metrics is linked to the type of cloud response hypothesized by its authors. The resolved lower-tropospheric mixing (LTMI D) is positively correlated to ECS for a subset of the SME having LTMI D over a threshold value. LTMI and the RH for the dry, descending branch of the Hadley cell (RH D) narrow and shift upward the posterior estimates of ECS in the SME, but the SME bias in RH D and concerns over poorly understood physical mechanisms suggest the narrowing could be spurious for both constraints. While calibrated SME results may not generalize to multimodel ensembles, they can enhance the process understanding of emergent constraints and serve as out-of-sample tests of robustness.

CLIMATE SENSITIVITY AND GROWTH RESPONSE OF TWO CONIFERS ON HIGH ELEVATION RIDGE AT WOLF KNOB, SHOSHONE FOREST, WY

2020 ◽  
Author(s):  
Laura Dye ◽  
◽  
Cori Butkiewicz ◽  
Zane Cooper ◽  
Bethany Coulthard ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Growth Response ◽  
High Elevation

scholarly journals Modeling vegetation greenness and its climate sensitivity with deep‐learning technology

2021 ◽  
Author(s):  
Zhiting Chen ◽  
Hongyan Liu ◽  
Chongyang Xu ◽  
Xiuchen Wu ◽  
Boyi Liang ◽  
...  
Keyword(s):  
Deep Learning ◽  
Climate Sensitivity ◽  
Learning Technology ◽  
Vegetation Greenness

Observational constraints on low cloud feedback reduce uncertainty of climate sensitivity

2021 ◽  
Author(s):  
Timothy A. Myers ◽  
Ryan C. Scott ◽  
Mark D. Zelinka ◽  
Stephen A. Klein ◽  
Joel R. Norris ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Cloud Feedback ◽  
Observational Constraints ◽  
Low Cloud
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