Ocean Response to a Climate Change Heat-Flux Perturbation in an Ocean Model and Its Corresponding Coupled Model

An ensemble of regional climate change scenarios for the North Sea is validated and analyzed. Five Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Models (GCMs) using three different Representative Concentration Pathways (RCPs) have been downscaled with the coupled atmosphere–ice–ocean model RCA4-NEMO. Validation of sea surface temperature (SST) against different datasets suggests that the model results are well within the spread of observational datasets. The ensemble mean SST with a bias of less than 1 ∘ C is the solution that fits the observations best and underlines the importance of ensemble modeling. The exchange of momentum, heat, and freshwater between atmosphere and ocean in the regional, coupled model compares well with available datasets. The climatological seasonal cycles of these fluxes are within the 95% confidence limits of the datasets. Towards the end of the 21st century the projected North Sea SST increases by 1.5 ∘ C (RCP 2.6), 2 ∘ C (RCP 4.5), and 4 ∘ C (RCP 8.5), respectively. Under this change the North Sea develops a specific pattern of the climate change signal for the air–sea temperature difference and latent heat flux in the RCP 4.5 and 8.5 scenarios. In the RCP 8.5 scenario the amplitude of the spatial heat flux anomaly increases to 5 W/m 2 at the end of the century. Different hypotheses are discussed that could contribute to the spatially non-uniform change in air–sea interaction. The most likely cause for an increased latent heat loss in the central western North Sea is a drier atmosphere towards the end of the century. Drier air in the lee of the British Isles affects the balance of the surface heat budget of the North Sea. This effect is an example of how regional characteristics modulate global climate change. For climate change projections on regional scales it is important to resolve processes and feedbacks at regional scales.

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Response of sea-ice models to perturbations in surface heat flux

Annals of Glaciology ◽

10.3189/s0260305500014026 ◽

1997 ◽

Vol 25 ◽

pp. 193-197 ◽

Cited By ~ 5

Author(s):

T. E. Arbetter ◽

J. A. Curry ◽

M. M. Holland ◽

J. A. Maslanik

Keyword(s):

Climate Change ◽

Heat Flux ◽

Sea Ice ◽

Surface Heat ◽

Heat Fluxes ◽

Ice Dynamics ◽

Surface Heat Fluxes ◽

Climate Simulations ◽

Sensitivity Studies ◽

Flux Perturbation

There are currently a variety of one- and two-dimensional sea-ice models being used for climate simulations and sensitivity studies. Though all the models can be timed to simulate current-day conditions to some degree of accuracy, the responses of each model to perturbations in forcing from the atmosphere or ocean are different. Thus, climate-change prediction depends on the choice of sea-ice model. In this study, the sensitivities of various sea-ice models to external heat-flux perturbations are examined in a systematic manner. Starting from similar baseline annual thicknesses, each model is subjected to an applied heat-flux perturbation to assess icemelt. Separate experiments are conducted to compare the response of each model to heat fluxes applied at the atmospheric and the oceanic interfaces. It is found that the magnitude of the heat-flux perturbation required to melt ice varies greatly among different models, with the largest difference arising between models that include ice dynamics vs those that do not. Most models show an asymmetry in the response to heat-flux perturbations applied at the top and bottom surfaces of the ice. This study has implications for the choice of sea-ice models used for climate-change simulations. It also gives insight to the accuracy required for observations and model simulations of the surface heat fluxes.

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The impact of perturbations to ocean-model parameters on climate and climate change in a coupled model

Climate Dynamics ◽

10.1007/s00382-008-0486-3 ◽

2008 ◽

Vol 34 (2-3) ◽

pp. 325-343 ◽

Cited By ~ 30

Author(s):

Chris M. Brierley ◽

Matthew Collins ◽

Alan J. Thorpe

Keyword(s):

Climate Change ◽

Coupled Model ◽

Ocean Model ◽

Model Parameters ◽

The Impact

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A Study of Response of the Equatorial Pacific SST to Doubled-CO2 Forcing in the Coupled CAM–1.5-Layer Reduced-Gravity Ocean Model

Journal of Physical Oceanography ◽

10.1175/jpo-d-12-0144.1 ◽

2013 ◽

Vol 43 (7) ◽

pp. 1288-1300 ◽

Cited By ~ 9

Author(s):

Fan Jia ◽

Lixin Wu

Keyword(s):

Heat Flux ◽

El Niño ◽

General Circulation ◽

El Nino ◽

Heat Budget ◽

Coupled Model ◽

Ocean Model ◽

Equatorial Pacific ◽

Shortwave Radiation ◽

Reduced Gravity

Abstract The response of the equatorial Pacific SST under CO2 doubling is investigated using Community Atmosphere Model, version 3.1 (CAM3.1)–1.5-layer reduced-gravity ocean (RGO) coupled model. A robust El Niño–like warming pattern is found in the equatorial Pacific. The surface heat budget analyses suggest the El Niño–like pattern results from a weakening of the Walker circulation. In the western equatorial Pacific, all the heat flux components are important to warm the ocean, with the vast majority canceled by entraiment cooling related to increased stratification. In the central-eastern Pacific, the oceanic horizontal advections along with longwave radiation and latent heat flux act to warm the ocean, with entrainment, shortwave radiation, and horizontal diffusion acting as damping terms. An enhanced annual cycle of SST in the equatorial Pacific is also found, which is driven by the ocean dynamical adjustments to changing winds in the eastern ocean. Although the ocean model used here is a simple reduced-gravity model, the El Niño–like response supports the results of some full ocean–atmosphere general circulation models (GCMs) performed for the World Climate Research Programme (WCRP) Coupled Model Intercomparison Project (CMIP) phase-5, indicating that the CAM3.1–RGO model can be taken as a useful and efficient tool to study equatorial Pacific response under changing climate.

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Response of sea-ice models to perturbations in surface heat flux

Annals of Glaciology ◽

10.1017/s0260305500014026 ◽

1997 ◽

Vol 25 ◽

pp. 193-197 ◽

Cited By ~ 3

Author(s):

T. E. Arbetter ◽

J. A. Curry ◽

M. M. Holland ◽

J. A. Maslanik

Keyword(s):

Climate Change ◽

Heat Flux ◽

Sea Ice ◽

Surface Heat ◽

Heat Fluxes ◽

Ice Dynamics ◽

Surface Heat Fluxes ◽

Climate Simulations ◽

Sensitivity Studies ◽

Flux Perturbation

There are currently a variety of one- and two-dimensional sea-ice models being used for climate simulations and sensitivity studies. Though all the models can be timed to simulate current-day conditions to some degree of accuracy, the responses of each model to perturbations in forcing from the atmosphere or ocean are different. Thus, climate-change prediction depends on the choice of sea-ice model. In this study, the sensitivities of various sea-ice models to external heat-flux perturbations are examined in a systematic manner. Starting from similar baseline annual thicknesses, each model is subjected to an applied heat-flux perturbation to assess icemelt. Separate experiments are conducted to compare the response of each model to heat fluxes applied at the atmospheric and the oceanic interfaces. It is found that the magnitude of the heat-flux perturbation required to melt ice varies greatly among different models, with the largest difference arising between models that include ice dynamics vs those that do not. Most models show an asymmetry in the response to heat-flux perturbations applied at the top and bottom surfaces of the ice. This study has implications for the choice of sea-ice models used for climate-change simulations. It also gives insight to the accuracy required for observations and model simulations of the surface heat fluxes.

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Evaluation and Sensitivity Analysis of an Ocean Model Response to Hurricane Ivan

Monthly Weather Review ◽

10.1175/2010mwr3104.1 ◽

2011 ◽

Vol 139 (3) ◽

pp. 921-945 ◽

Cited By ~ 41

Author(s):

G. R. Halliwell ◽

L. K. Shay ◽

J. K. Brewster ◽

W. J. Teague

Keyword(s):

Heat Flux ◽

Surface Heat Flux ◽

Vertical Mixing ◽

Ocean Model ◽

Surface Heat ◽

Wind Speeds ◽

Hurricane Ivan ◽

Sst Cooling ◽

Ocean Response ◽

Model Response

Abstract An ocean model response to Hurricane Ivan (2004) over the northwest Caribbean Sea and Gulf of Mexico is evaluated to guide strategies for improving performance during strong forcing events in a region with energetic ocean features with the ultimate goal of improving coupled tropical cyclone forecasts. Based on prior experience, a control experiment is performed using quasi-optimal choices of initial ocean fields, atmospheric forcing fields, air–sea flux parameterizations, vertical mixing parameterizations, and both horizontal and vertical resolutions. Alternate experiments are conducted by altering one single model attribute and comparing the results to SST analyses and moored ADCP current measurements to quantify the sensitivity to that attribute and identify where to concentrate model improvement efforts. Atmospheric forcing that does not resolve the eye and eyewall of the storm (scales >10 km) substantially degrades the ocean response. Ordering other model attributes from greatest to least sensitivity, ocean model initialization with regard to the accuracy of upper-ocean temperature–salinity profiles along with accurate location of ocean currents and eddies is the most important factor for ensuring good ocean model performance. Ocean dynamics ranks second in this energetic ocean region because a one-dimensional ocean model fails to capture important physical processes that affect SST cooling. Wind stress drag coefficient parameterizations that yield values exceeding 2.5 × 10−3 at high wind speeds or that remain <2.0 × 10−3 over all wind speeds reduce the realism of wind-driven current profiles and have a large impact on both SST cooling and the heat flux from ocean to atmosphere. Turbulent heat flux drag coefficient parameterizations substantially impact the surface heat flux while having little impact on SST cooling, which is primarily controlled by entrainment at the mixed layer base. Vertical mixing parameterizations have a moderate impact on SST cooling but a comparatively larger impact on surface heat flux. The impacts of altering the horizontal and vertical resolutions are small, with horizontal resolution of ≈10 km and vertical resolution of ≈10 m in the mixed layer being adequate. Optimal choices of all attributes for simulating the ocean response to Ivan are identified.

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Impact of air–sea coupling on the climate change signal over the Iberian Peninsula

Climate Dynamics ◽

10.1007/s00382-021-05812-x ◽

2021 ◽

Author(s):

Alba de la Vara ◽

William Cabos ◽

Dmitry V. Sein ◽

Claas Teichmann ◽

Daniela Jacob

Keyword(s):

Climate Change ◽

Iberian Peninsula ◽

Mediterranean Sea ◽

Large Scale ◽

Regional Distribution ◽

Coupled Model ◽

Climate Change Signal ◽

The North ◽

The Mediterranean ◽

The Impact

AbstractIn this work we use a regional atmosphere–ocean coupled model (RAOCM) and its stand-alone atmospheric component to gain insight into the impact of atmosphere–ocean coupling on the climate change signal over the Iberian Peninsula (IP). The IP climate is influenced by both the Atlantic Ocean and the Mediterranean sea. Complex interactions with the orography take place there and high-resolution models are required to realistically reproduce its current and future climate. We find that under the RCP8.5 scenario, the generalized 2-m air temperature (T2M) increase by the end of the twenty-first century (2070–2099) in the atmospheric-only simulation is tempered by the coupling. The impact of coupling is specially seen in summer, when the warming is stronger. Precipitation shows regionally-dependent changes in winter, whilst a drier climate is found in summer. The coupling generally reduces the magnitude of the changes. Differences in T2M and precipitation between the coupled and uncoupled simulations are caused by changes in the Atlantic large-scale circulation and in the Mediterranean Sea. Additionally, the differences in projected changes of T2M and precipitation with the RAOCM under the RCP8.5 and RCP4.5 scenarios are tackled. Results show that in winter and summer T2M increases less and precipitation changes are of a smaller magnitude with the RCP4.5. Whilst in summer changes present a similar regional distribution in both runs, in winter there are some differences in the NW of the IP due to differences in the North Atlantic circulation. The differences in the climate change signal from the RAOCM and the driving Global Coupled Model show that regionalization has an effect in terms of higher resolution over the land and ocean.

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Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models

npj Climate and Atmospheric Science ◽

10.1038/s41612-020-00159-2 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Zhili Wang ◽

Lei Lin ◽

Yangyang Xu ◽

Huizheng Che ◽

Xiaoye Zhang ◽

...

Keyword(s):

Climate Change ◽

Radiative Forcing ◽

Impact Analysis ◽

Climate Model ◽

Regional Climate ◽

Eastern China ◽

Coupled Model ◽

Regional Climate Change ◽

Anthropogenic Aerosol ◽

Wide Range

AbstractAnthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.

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Kuroshio intrusion in the Luzon Strait in an eddy-resolving ocean model and air-sea coupled model

Acta Oceanologica Sinica ◽

10.1007/s13131-020-1670-5 ◽

2020 ◽

Vol 39 (11) ◽

pp. 52-68

Author(s):

Qian Yang ◽

Hailong Liu ◽

Pengfei Lin ◽

Yiwen Li

Keyword(s):

Coupled Model ◽

Ocean Model ◽

Luzon Strait ◽

Kuroshio Intrusion

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Water Budgets of Managed Forests in Northeast Germany under Climate Change—Results from a Model Study on Forest Monitoring Sites

Applied Sciences ◽

10.3390/app11052403 ◽

2021 ◽

Vol 11 (5) ◽

pp. 2403

Author(s):

Daniel Ziche ◽

Winfried Riek ◽

Alexander Russ ◽

Rainer Hentschel ◽

Jan Martin

Keyword(s):

Climate Change ◽

Climate Models ◽

Regional Climate ◽

Coupled Model ◽

Regional Climate Models ◽

Realistic Model ◽

Forest Monitoring ◽

Climate Change Scenarios ◽

Historical Time ◽

Time Period

To develop measures to reduce the vulnerability of forests to drought, it is necessary to estimate specific water balances in sites and to estimate their development with climate change scenarios. We quantified the water balance of seven forest monitoring sites in northeast Germany for the historical time period 1961–2019, and for climate change projections for the time period 2010–2100. We used the LWF-BROOK90 hydrological model forced with historical data, and bias-adjusted data from two models of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) downscaled with regional climate models under the representative concentration pathways (RCPs) 2.6 and 8.5. Site-specific monitoring data were used to give a realistic model input and to calibrate and validate the model. The results revealed significant trends (evapotranspiration, dry days (actual/potential transpiration < 0.7)) toward drier conditions within the historical time period and demonstrate the extreme conditions of 2018 and 2019. Under RCP8.5, both models simulate an increase in evapotranspiration and dry days. The response of precipitation to climate change is ambiguous, with increasing precipitation with one model. Under RCP2.6, both models do not reveal an increase in drought in 2071–2100 compared to 1990–2019. The current temperature increase fits RCP8.5 simulations, suggesting that this scenario is more realistic than RCP2.6.

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