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

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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Dynamic Downscaling of the Impact of Climate Change on the Ocean Circulation in the Galápagos Archipelago

Advances in Meteorology ◽

10.1155/2013/837432 ◽

2013 ◽

Vol 2013 ◽

pp. 1-18 ◽

Cited By ~ 7

Author(s):

Yanyun Liu ◽

Lian Xie ◽

John M. Morrison ◽

Daniel Kamykowski

Keyword(s):

Climate Change ◽

Ocean Circulation ◽

Global Climate Change ◽

Climate Model ◽

Global Climate ◽

Ocean Model ◽

Reanalysis Dataset ◽

Equatorial Undercurrent ◽

Galapagos Archipelago ◽

The Impact

The regional impact of global climate change on the ocean circulation around the Galápagos Archipelago is studied using the Hybrid Coordinate Ocean Model (HYCOM) configured for a four-level nested domain system. The modeling system is validated and calibrated using daily atmospheric forcing derived from the NCEP/NCAR reanalysis dataset from 1951 to 2007. The potential impact of future anthropogenic global warming (AGW) in the Galápagos region is examined using the calibrated HYCOM with forcing derived from the IPCC-AR4 climate model. Results show that although the oceanic variability in the entire Galápagos region is significantly affected by global climate change, the degree of such effects is inhomogeneous across the region. The upwelling region to the west of the Isabella Island shows relatively slower warming trends compared to the eastern Galápagos region. Diagnostic analysis suggests that the variability in the western Galápagos upwelling region is affected mainly by equatorial undercurrent (EUC) and Panama currents, while the central/east Galápagos is predominantly affected by both Peru and EUC currents. The inhomogeneous responses in different regions of the Galápagos Archipelago to future AGW can be explained by the incoherent changes of the various current systems in the Galápagos region as a result of global climate change.

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Impact of Resolution on the Tropical Pacific Circulation in a Matrix of Coupled Models

Journal of Climate ◽

10.1175/2008jcli2537.1 ◽

2009 ◽

Vol 22 (10) ◽

pp. 2541-2556 ◽

Cited By ~ 69

Author(s):

Malcolm J. Roberts ◽

A. Clayton ◽

M.-E. Demory ◽

J. Donners ◽

P. L. Vidale ◽

...

Keyword(s):

Coupled Model ◽

Walker Circulation ◽

Ocean Model ◽

Tropical Pacific ◽

Coupled Models ◽

Model Stability ◽

The Mean ◽

The Impact ◽

Mean State ◽

The Tropical Pacific

Abstract Results are presented from a matrix of coupled model integrations, using atmosphere resolutions of 135 and 90 km, and ocean resolutions of 1° and 1/3°, to study the impact of resolution on simulated climate. The mean state of the tropical Pacific is found to be improved in the models with a higher ocean resolution. Such an improved mean state arises from the development of tropical instability waves, which are poorly resolved at low resolution; these waves reduce the equatorial cold tongue bias. The improved ocean state also allows for a better simulation of the atmospheric Walker circulation. Several sensitivity studies have been performed to further understand the processes involved in the different component models. Significantly decreasing the horizontal momentum dissipation in the coupled model with the lower-resolution ocean has benefits for the mean tropical Pacific climate, but decreases model stability. Increasing the momentum dissipation in the coupled model with the higher-resolution ocean degrades the simulation toward that of the lower-resolution ocean. These results suggest that enhanced ocean model resolution can have important benefits for the climatology of both the atmosphere and ocean components of the coupled model, and that some of these benefits may be achievable at lower ocean resolution, if the model formulation allows.

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Influence of Ocean and Atmosphere Components on Simulated Climate Sensitivities

Journal of Climate ◽

10.1175/jcli-d-12-00121.1 ◽

2013 ◽

Vol 26 (1) ◽

pp. 231-245 ◽

Cited By ~ 27

Author(s):

Michael Winton ◽

Alistair Adcroft ◽

Stephen M. Griffies ◽

Robert W. Hallberg ◽

Larry W. Horowitz ◽

...

Keyword(s):

Sea Ice ◽

Climate Models ◽

Climate Model ◽

Model Simulation ◽

Coupled Model ◽

Ocean Model ◽

Historical Simulation ◽

Model Version ◽

Salinity Response ◽

The Impact

Abstract The influence of alternative ocean and atmosphere subcomponents on climate model simulation of transient sensitivities is examined by comparing three GFDL climate models used for phase 5 of the Coupled Model Intercomparison Project (CMIP5). The base model ESM2M is closely related to GFDL’s CMIP3 climate model version 2.1 (CM2.1), and makes use of a depth coordinate ocean component. The second model, ESM2G, is identical to ESM2M but makes use of an isopycnal coordinate ocean model. The authors compare the impact of this “ocean swap” with an “atmosphere swap” that produces the GFDL Climate Model version 3 (CM3) by replacing the AM2 atmospheric component with AM3 while retaining a depth coordinate ocean model. The atmosphere swap is found to have much larger influence on sensitivities of global surface temperature and Northern Hemisphere sea ice cover. The atmosphere swap also introduces a multidecadal response time scale through its indirect influence on heat uptake. Despite significant differences in their interior ocean mean states, the ESM2M and ESM2G simulations of these metrics of climate change are very similar, except for an enhanced high-latitude salinity response accompanied by temporarily advancing sea ice in ESM2G. In the ESM2G historical simulation this behavior results in the establishment of a strong halocline in the subpolar North Atlantic during the early twentieth century and an associated cooling, which are counter to observations in that region. The Atlantic meridional overturning declines comparably in all three models.

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The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

Geoscientific Model Development ◽

10.5194/gmd-9-3655-2016 ◽

2016 ◽

Vol 9 (10) ◽

pp. 3655-3670 ◽

Cited By ~ 33

Author(s):

Helene T. Hewitt ◽

Malcolm J. Roberts ◽

Pat Hyder ◽

Tim Graham ◽

Jamie Rae ◽

...

Keyword(s):

High Resolution ◽

Coupled Model ◽

Ocean Model ◽

The Body ◽

Western Boundary ◽

Coupled Models ◽

Technical Developments ◽

Enhanced Resolution ◽

Circumpolar Current ◽

The Impact

Abstract. There is mounting evidence that resolving mesoscale eddies and western boundary currents as well as topographically controlled flows can play an important role in air–sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4 to 1/12° (28 to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling period reduced from 3 hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20-year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced sea surface temperature (SST) biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high-frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

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The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

10.5194/gmd-2016-87 ◽

2016 ◽

Cited By ~ 2

Author(s):

Helene T. Hewitt ◽

Malcolm J. Roberts ◽

Pat Hyder ◽

Tim Graham ◽

Jamie Rae ◽

...

Keyword(s):

High Resolution ◽

Coupled Model ◽

Ocean Model ◽

The Body ◽

Coupled Models ◽

Surface Ocean ◽

Technical Developments ◽

Enhanced Resolution ◽

Circumpolar Current ◽

The Impact

Abstract. There is mounting evidence that resolving mesoscale eddies and boundary currents in the surface ocean field can play an important role in air-sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4° to 1/12° (28 km to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling frequency increased from 3-hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20 year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced Sea Surface Temperature biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

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Introduction to A Regional Coupled Forecasting System

10.5194/egusphere-egu2020-12626 ◽

2020 ◽

Author(s):

Mingkui Li ◽

Shaoqing Zhang

Keyword(s):

National Laboratory ◽

Coupled Model ◽

Ocean Model ◽

Asia Pacific ◽

Model Resolution ◽

Coupled Models ◽

Regional Ocean Model System ◽

Extended Range ◽

Coupled Data Assimilation ◽

The Impact

A regional coupled prediction system for the Asia-Pacific area (AP-RCP) has been established. The AP-RCP system consists of WRF-ROMS (Weather Research and Forecast and Regional Ocean Model System) coupled models combined with local observing information through dynamically downscaling coupled data assimilation. The system generates 18-day atmospheric and oceanic environment forecasts on a daily quasi-operational schedule at Qingdao Pilot National Laboratory for Marine Science and Technology (QNLM). The AP-RCP system mainly includes 2 different coupled model resolutions: 27km WRF coupled with 9km ROMS, and 9km WRF coupled with 3km ROMS. This study evaluates the impact of enhancing coupled model resolution on the extended-range forecasts, focusing on forecasts of typhoon onset, and improved precipitation and typhoon intensity forecasts. Results show that enhancing coupled model resolution is a necessary step to realize the extended-range predictability of the atmosphere and ocean environmental conditions that include a plenty of local details. The next challenges include improving the planetary boundary physics and the representation of air-sea and air-land interactions when the model can resolve the kilometer or sub-kilometer processes.

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Impact of biogeochemistry feedbacks on the projected climate change signal over the Indian Continent

10.5194/egusphere-egu2020-19402 ◽

2020 ◽

Author(s):

Dmitry Sein ◽

William Cabos ◽

Pankaj Kumar ◽

Vladimir Ryabchenko ◽

Stanislav Martyanov ◽

...

Keyword(s):

Climate Change ◽

Marine Ecosystem ◽

Regional Model ◽

Ocean Model ◽

Global Ocean ◽

Future Climate Change ◽

Climate Change Signal ◽

Water Type ◽

Substantial Impact ◽

The Impact

There are few studies dedicated to assessing the impact of biogeochemistry feedbacks on the climate change signal. In this study, we evaluate this impact in a future climate change scenario over the Indian subcontinent with the coupled regional model ROM in the Indian CORDEX area.In ROM a global ocean model (MPIOM) with regionally high horizontal resolution (up to 15 km resolution in the Bay of Bengal) is coupled to an atmospheric regional model (REMO, with 25 km resolution) and global terrestrial hydrology model. The ocean and the atmosphere are interacting within the region covered by the atmospheric domain. Outside this domain, the ocean model is not coupled to the atmosphere, being driven by prescribed atmospheric forcing, thus running in so-called stand-alone mode.To assess the impact of biogeochemical feedbacks on the climate change signal, we compare two simulations with ROM. In both simulations, the model is driven by data from a climate change simulation under the RCP 8.5 scenario with the MPI-ESM global model and differ only in the activation of the biochemistry module of MPIOM. In the first simulation, we use a light attenuation parameterization based on the Jerlov water types, when the attenuation coefficient varies spatially depending on the water type specified but does not vary in time. In the second simulation, we introduce the biochemical feedbacks as implemented in the global ocean biogeochemistry model HAMOCC. &#160;Both simulations capture the main features of the present time atmospheric and oceanic variability in the region and the model with HAMOCC reproduces well the intra-annual dynamics of the marine ecosystem in the northern Indian Ocean.A comparison of the simulated changes in atmospheric variables shows that the feedbacks have a substantial impact on the climate change signal for precipitation and air temperature, especially over the central Indian region.Acknowledgement: The work was supported by the Russian Science Foundation (Project 19-47-02015) and Indian project no. DST/INT/RUS/RSF/P-33/G.

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Investigation of the Climate Change Effects on the Mediterranean Region with the Hypothetical inclusion of the Istanbul Isthmus

10.5194/egusphere-egu2020-22217 ◽

2020 ◽

Author(s):

Elcin Tan

Keyword(s):

Climate Change ◽

Land Surface ◽

Mediterranean Region ◽

Climate Model ◽

Wrf Model ◽

Ocean Model ◽

Atmospheric Conditions ◽

Sea Level Changes ◽

The Mediterranean ◽

The Impact

A debate on the probable Istanbul Isthmus Project that may have catastrophic impacts on our ecosystem has been recently accelerated in public, due to the fact that the approved environmental impact assessment (EIA) report of the hypothetical Istanbul Isthmus (HII) Project has recently been announced. The EIA report indicates that the assessment covers only the current conditions and the conditions that may arise during the construction of the HII. Unfortunately, The EIA report did not evaluate the climate change impact on either the Istanbul Area or Mediterranean Region after the inclusion of the HII, only the current conditions were evaluated. Therefore, the aim of this study is to investigate the impact of HII on the climate of the Mediterranean Region. The climate version of the WRF Model is utilized with 9 km resolution for the Region 12: Mediterranean (CORDEX) for the historical conditions and RCP8.5 scenarios of available climate model results from CMIP5 and CMIP6 projects. Land surface and land use maps are prepared by following the EIA report if the necessary information is included, otherwise, the current conditions are applied. The atmospheric conditions were not coupled to an Ocean Model, only the Sea Surface Temperature (SST) values of the Ocean Models are coupled to the WRF model during both historical and future simulations. The model results are evaluated in terms of temperature, precipitation, and sea-level changes. Consequently, the results indicate that the HII may decrease the resilience of the Mediterranean Region to Climate Change.

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Modeling the Impact of Climate Change on the Dynamics of Rift Valley Fever

Computational and Mathematical Methods in Medicine ◽

10.1155/2014/627586 ◽

2014 ◽

Vol 2014 ◽

pp. 1-12 ◽

Cited By ~ 13

Author(s):

Saul C. Mpeshe ◽

Livingstone S. Luboobi ◽

Yaw Nkansah-Gyekye

Keyword(s):

Climate Change ◽

Rift Valley ◽

Rift Valley Fever ◽

Model Parameters ◽

Climatic Data ◽

Elasticity Analysis ◽

Expected Number ◽

Valley Fever ◽

Temperature And Precipitation ◽

The Impact

A deterministic SEIR model of rift valley fever (RVF) with climate change parameters was considered to compute the basic reproduction numberℛ0and investigate the impact of temperature and precipitation onℛ0. To study the effect of model parameters toℛ0, sensitivity and elasticity analysis ofℛ0were performed. When temperature and precipitation effects are not considered,ℛ0is more sensitive to the expected number of infectedAedesspp. due to one infected livestock and more elastic to the expected number of infected livestock due to one infectedAedesspp. When climatic data are used,ℛ0is found to be more sensitive and elastic to the expected number of infected eggs laid byAedesspp. via transovarial transmission, followed by the expected number of infected livestock due to one infectedAedesspp. and the expected number of infectedAedesspp. due to one infected livestock for both regions Arusha and Dodoma. These results call for attention to parameters regarding incubation period, the adequate contact rate ofAedesspp. and livestock, the infective periods of livestock andAedesspp., and the vertical transmission inAedesspecies.

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