scholarly journals North Pacific zonal wind response to sea ice loss in the Polar Amplification Model Intercomparison Project and its downstream implications

2020 ◽  
Vol 55 (7-8) ◽  
pp. 1779-1792
Author(s):  
Bryn Ronalds ◽  
Elizabeth A. Barnes ◽  
Rosie Eade ◽  
Yannick Peings ◽  
Michael Sigmond
Keyword(s):  
Sea Ice ◽  
Zonal Wind ◽  
North Pacific ◽  
Model Intercomparison ◽  
Polar Amplification ◽  
Wind Response ◽  
Intercomparison Project

scholarly journals Response of Northern Hemisphere weather and climate to Arctic sea ice decline: Resolution independence in Polar Amplification Model Intercomparison Project (PAMIP) simulations

2021 ◽  
pp. 1-39
Author(s):  
Jan Streffing ◽  
Tido Semmler ◽  
Lorenzo Zampieri ◽  
Thomas Jung
Keyword(s):  
Sea Ice ◽  
Horizontal Resolution ◽  
Arctic Sea Ice ◽  
Model Intercomparison ◽  
Polar Amplification ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
Weather And Climate ◽  
Intercomparison Project ◽  
The Impact

AbstractThe impact of Arctic sea ice decline on the weather and climate in mid-latitudes is still much debated, with observation suggesting a strong and models a much weaker link. In this study, we use the atmospheric model OpenIFS, in a set of model experiments following the protocol outlined in the Polar Amplification Model Intercomparison Project (PAMIP), to investigate whether the simulated atmospheric response to future changes in Arctic sea ice fundamentally depends on model resolution. More specifically, we increase the horizontal resolution of the model from 125km to 39km with 91 vertical levels; in a second step resolution is further increased to 16km with 137 levels in the vertical. The model does produce a response to sea ice decline with a weaker mid latitude Atlantic jet and increased blocking in the high latitude Atlantic, but no sensitivity to resolution can be detected with 100 members. Furthermore we find that the ensemble convergence toward the mean is not impacted by the model resolutions considered here.

Response of Northern Hemisphere weather and climate to Arctic sea ice decline: The role of resolution in Polar Amplification Model Intercomparison Project (PAMIP) simulations

2021 ◽  
Author(s):  
Jan Streffing ◽  
Tido Semmler ◽  
Lorenzo Zampieri ◽  
Thomas Jung
Keyword(s):  
Sea Ice ◽  
Arctic Sea Ice ◽  
Atmospheric Response ◽  
Model Intercomparison ◽  
Polar Amplification ◽  
Sea Ice Decline ◽  
Arctic Sea ◽  
Weather And Climate ◽  
Intercomparison Project ◽  
The Mean

<p>The impact of Arctic sea ice decline on the weather and climate in mid-latitudes is still much debated, with observation suggesting a strong and models a much weaker link. In this study, we use the atmospheric model OpenIFS, in a set of model experiments following the protocol outlined in the Polar Amplification Model Intercomparison Project (PAMIP), to investigate whether the simulated atmospheric response to future changes in Arctic sea ice fundamentally depends on model resolution. More specifically, we increase the horizontal resolution of the model from 125km to 39km with 91 vertical levels; in a second step resolution is further increased to 16km with 137 levels in the vertical. We find that neither the mean atmospheric response nor the ensemble convergence toward the mean are strongly impacted by the model resolutions considered here.</p>

scholarly journals The Polar Amplification Model Intercomparison Project (PAMIP) contribution to CMIP6: investigating the causes and consequences of polar amplification

2018 ◽  
Author(s):  
Doug M. Smith ◽  
James A. Screen ◽  
Clara Deser ◽  
Judah Cohen ◽  
John C. Fyfe ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Sea Surface ◽  
Model Intercomparison ◽  
Physical Processes ◽  
Polar Amplification ◽  
Arctic Sea ◽  
Intercomparison Project

Abstract. Polar amplification – the phenomenon that external radiative forcing produces a larger change in surface temperature at high latitudes than the global average – is a key aspect of anthropogenic climate change, but its causes and consequences are not fully understood. The Polar Amplification Model Intercomparison Project (PAMIP) contribution to the Sixth Coupled Model Intercomparison Project (CMIP6, Eyring et al. 2016) seeks to improve our understanding of this phenomenon through a coordinated set of numerical model experiments documented here. In particular, PAMIP will address the following primary questions: 1. What are the relative roles of local sea ice and remote sea surface temperature changes in driving polar amplification? 2. How does the global climate system respond to changes in Arctic and Antarctic sea ice? These issues will be addressed with multi-model simulations that are forced with different combinations of sea ice and/or sea surface temperatures representing present day, pre-industrial and future conditions. The use of three time periods allows the signals of interest to be diagnosed in multiple ways. Lower priority tier experiments are proposed to investigate additional aspects and provide further understanding of the physical processes. These experiments will address the following specific questions: What role does ocean-atmosphere coupling play in the response to sea ice? How and why does the atmospheric response to Arctic sea ice depend on the pattern of sea ice forcing? How and why does the atmospheric response to Arctic sea ice depend on the model background state? What are the roles of local sea ice and remote sea surface temperature in polar amplification, and the response to sea ice, over the recent period since 1979? How does the response to sea ice evolve on decadal and longer timescales? A key goal of PAMIP is to determine the real world situation using imperfect climate models. Although the experiments proposed here form a coordinated set, we anticipate a large spread across models. However, this spread will be exploited by seeking emergent constraints in which model uncertainty may be reduced by using an observable quantity that physically explains the inter-model spread. In summary, PAMIP will improve our understanding of the physical processes that drive polar amplification and its global climate impacts, thereby reducing the uncertainties in future projections and predictions of climate change and variability.

scholarly journals The Polar Amplification Model Intercomparison Project (PAMIP) contribution to CMIP6: investigating the causes and consequences of polar amplification

2019 ◽  
Vol 12 (3) ◽  
pp. 1139-1164 ◽  
Author(s):  
Doug M. Smith ◽  
James A. Screen ◽  
Clara Deser ◽  
Judah Cohen ◽  
John C. Fyfe ◽  
...  
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Global Climate ◽  
Arctic Sea Ice ◽  
Sea Surface ◽  
Model Intercomparison ◽  
Physical Processes ◽  
Polar Amplification ◽  
Arctic Sea ◽  
Intercomparison Project

Abstract. Polar amplification – the phenomenon where external radiative forcing produces a larger change in surface temperature at high latitudes than the global average – is a key aspect of anthropogenic climate change, but its causes and consequences are not fully understood. The Polar Amplification Model Intercomparison Project (PAMIP) contribution to the sixth Coupled Model Intercomparison Project (CMIP6; Eyring et al., 2016) seeks to improve our understanding of this phenomenon through a coordinated set of numerical model experiments documented here. In particular, PAMIP will address the following primary questions: (1) what are the relative roles of local sea ice and remote sea surface temperature changes in driving polar amplification? (2) How does the global climate system respond to changes in Arctic and Antarctic sea ice? These issues will be addressed with multi-model simulations that are forced with different combinations of sea ice and/or sea surface temperatures representing present-day, pre-industrial and future conditions. The use of three time periods allows the signals of interest to be diagnosed in multiple ways. Lower-priority tier experiments are proposed to investigate additional aspects and provide further understanding of the physical processes. These experiments will address the following specific questions: what role does ocean–atmosphere coupling play in the response to sea ice? How and why does the atmospheric response to Arctic sea ice depend on the pattern of sea ice forcing? How and why does the atmospheric response to Arctic sea ice depend on the model background state? What have been the roles of local sea ice and remote sea surface temperature in polar amplification, and the response to sea ice, over the recent period since 1979? How does the response to sea ice evolve on decadal and longer timescales? A key goal of PAMIP is to determine the real-world situation using imperfect climate models. Although the experiments proposed here form a coordinated set, we anticipate a large spread across models. However, this spread will be exploited by seeking “emergent constraints” in which model uncertainty may be reduced by using an observable quantity that physically explains the intermodel spread. In summary, PAMIP will improve our understanding of the physical processes that drive polar amplification and its global climate impacts, thereby reducing the uncertainties in future projections and predictions of climate change and variability.

scholarly journals CAS FGOALS-f3-L Large-ensemble Simulations for the CMIP6 Polar Amplification Model Intercomparison Project

2021 ◽  
Author(s):  
Bian He ◽  
Xiaoqi Zhang ◽  
Anmin Duan ◽  
Qing Bao ◽  
Yimin Liu ◽  
...  
Keyword(s):  
Time Lag ◽  
The Arctic ◽  
Global Ocean ◽  
Arctic Amplification ◽  
Model Intercomparison ◽  
Large Ensemble ◽  
Sea Ice Concentration ◽  
Ensemble Simulations ◽  
Polar Amplification ◽  
Intercomparison Project

AbstractLarge-ensemble simulations of the atmosphere-only time-slice experiments for the Polar Amplification Model Intercomparison Project (PAMIP) were carried out by the model group of the Chinese Academy of Sciences (CAS) Flexible Global Ocean-Atmosphere-Land System (FGOALS-f3-L). Eight groups of experiments forced by different combinations of the sea surface temperature (SST) and sea ice concentration (SIC) for pre-industrial, present-day, and future conditions were performed and published. The time-lag method was used to generate the 100 ensemble members, with each member integrating from 1 April 2000 to 30 June 2001 and the first two months as the spin-up period. The basic model responses of the surface air temperature (SAT) and precipitation were documented. The results indicate that Arctic amplification is mainly caused by Arctic SIC forcing changes. The SAT responses to the Arctic SIC decrease alone show an obvious increase over high latitudes, which is similar to the results from the combined forcing of SST and SIC. However, the change in global precipitation is dominated by the changes in the global SST rather than SIC, partly because tropical precipitation is mainly driven by local SST changes. The uncertainty of the model responses was also investigated through the analysis of the large-ensemble members. The relative roles of SST and SIC, together with their combined influence on Arctic amplification, are also discussed. All of these model datasets will contribute to PAMIP multi-model analysis and improve the understanding of polar amplification.

Observationally constrained multi-model atmospheric response to future Arctic sea ice loss 

2021 ◽  
Author(s):  
Doug Smith ◽  
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Arctic Sea Ice ◽  
Model Intercomparison ◽  
Scientific Debate ◽  
Model Response ◽  
Arctic Sea ◽  
Intercomparison Project ◽  
Constrained Model ◽  
Arctic Sea Ice Loss

<p>The possibility that Arctic sea ice loss could weaken mid-latitude westerlies and promote more severe cold winters has sparked more than a decade of scientific debate, with support from observations but inconclusive modelling evidence. Here we analyse a large multi-model ensemble of coordinated experiments from the Polar Amplification Model Intercomparison Project and find that the modelled response is proportional to the simulated eddy momentum feedback, and that this is underestimated in all models. Hence, we derive an observationally constrained model response showing a modest weakening of mid-latitude tropospheric and stratospheric winds, an equatorward shift of the Atlantic and Pacific storm tracks, and a negative North Atlantic Oscillation. Although our constrained response is consistent with observed relationships which have weakened recently, we caution that emergent constraints may only provide a lower bound.</p>

scholarly journals Experimental and diagnostic protocol for the physical component of the CMIP6 Ocean Model Intercomparison Project (OMIP)

2016 ◽  
Author(s):  
Stephen M. Griffies ◽  
Gokhan Danabasoglu ◽  
Paul J. Durack ◽  
Alistair J. Adcroft ◽  
V. Balaji ◽  
...  
Keyword(s):  
Sea Ice ◽  
Global Climate ◽  
Coupled Model ◽  
Companion Paper ◽  
Ocean Model ◽  
Global Ocean ◽  
Model Intercomparison ◽  
Experimental Protocol ◽  
Diagnostic Protocol ◽  
Intercomparison Project

Abstract. The Ocean Model Intercomparison Project (OMIP) aims to provide a framework for evaluating, understanding, and improving the ocean and sea-ice components of global climate and earth system models contributing to the Coupled Model Intercomparison Project Phase 6 (CMIP6). OMIP addresses these aims in two complementary manners: (A) by providing an experimental protocol for global ocean/sea-ice models run with a prescribed atmospheric forcing, (B) by providing a protocol for ocean diagnostics to be saved as part of CMIP6. We focus here on the physical component of OMIP, with a companion paper (Orr et al., 2016) offering details for the inert chemistry and interactive biogeochemistry. The physical portion of the OMIP experimental protocol follows that of the interannual Coordinated Ocean-ice Reference Experiments (CORE-II). Since 2009, CORE-I (Normal Year Forcing) and CORE-II have become the standard method to evaluate global ocean/sea-ice simulations and to examine mechanisms for forced ocean climate variability. The OMIP diagnostic protocol is relevant for any ocean model component of CMIP6, including the DECK (Diagnostic, Evaluation and Characterization of Klima experiments), historical simulations, FAFMIP (Flux Anomaly Forced MIP), C4MIP (Coupled Carbon Cycle Climate MIP), DAMIP (Detection and Attribution MIP), DCPP (Decadal Climate Prediction Project), ScenarioMIP (Scenario MIP), as well as the ocean-sea ice OMIP simulations. The bulk of this paper offers scientific rationale for saving these diagnostics.

A Role for Barotropic Eddy–Mean Flow Feedbacks in the Zonal Wind Response to Sea Ice Loss and Arctic Amplification

2019 ◽  
Vol 32 (21) ◽  
pp. 7469-7481 ◽  
Author(s):  
Bryn Ronalds ◽  
Elizabeth A. Barnes
Keyword(s):  
Sea Ice ◽  
North Atlantic ◽  
Zonal Wind ◽  
Jet Stream ◽  
Arctic Amplification ◽  
Mean Flow ◽  
Jet Streams ◽  
The North ◽  
Wind Response ◽  
The North Pacific

Abstract Previous studies have suggested that, in the zonal mean, the climatological Northern Hemisphere wintertime eddy-driven jet streams will weaken and shift equatorward in response to Arctic amplification and sea ice loss. However, multiple studies have also pointed out that this response has strong regional differences across the two ocean basins, with the North Atlantic jet stream generally weakening across models and the North Pacific jet stream showing signs of strengthening. Based on the zonal wind response with a fully coupled model, this work sets up two case studies using a barotropic model to test a dynamical mechanism that can explain the differences in zonal wind response in the North Pacific versus the North Atlantic. Results indicate that the differences between the two basins are due, at least in part, to differences in the proximity of the jet streams to the sea ice loss, and that in both cases the eddies act to increase the jet speed via changes in wave breaking location and frequency. Thus, while baroclinic arguments may account for an initial reduction in the midlatitude winds through thermal wind balance, eddy–mean flow feedbacks are likely instrumental in determining the final total response and actually act to strengthen the eddy-driven jet stream.

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