scholarly journals Influence of XBT Temperature Bias on Decadal Climate Prediction with a Coupled Climate Model

2011 ◽  
Vol 24 (20) ◽  
pp. 5303-5308 ◽  
Author(s):  
Sayaka Yasunaka ◽  
Masayoshi Ishii ◽  
Masahide Kimoto ◽  
Takashi Mochizuki ◽  
Hideo Shiogama
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Initial Conditions ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Prediction ◽  
Temperature Bias ◽  
Subsurface Ocean ◽  
Decadal Climate ◽  
Decadal Climate Prediction

Abstract The influence of the expendable bathythermograph (XBT) depth bias correction on decadal climate prediction is presented by using a coupled atmosphere–ocean general circulation model called the Model for Interdisciplinary Research on Climate 3 (MIROC3). The global mean subsurface ocean temperatures that were simulated by the model with the prescribed anthropogenic and natural forcing are consistent with bias-corrected observations from the mid-1960s onward, but not with uncorrected observations. The latter is reflected by biases in subsurface ocean temperatures, particularly along thermoclines in the tropics and subtropics. When the correction is not applied to XBT observations, these biases are retained in data assimilation results for the model’s initial conditions. Hindcasting past Pacific decadal oscillations (PDOs) is more successful in the experiment with the bias-corrected observations than that without the correction. Improvement of skill in predicting 5-yr mean vertically average ocean subsurface temperature is also seen in the tropical and the central North Pacific where PDO-related signals appear large.

scholarly journals Modelling the impacts of climate change on tropospheric ozone over three centuries

2011 ◽  
Vol 11 (2) ◽  
pp. 6805-6843 ◽  
Author(s):  
G. B. Hedegaard ◽  
A. Gross ◽  
J. H. Christensen ◽  
W. May ◽  
H. Skov ◽  
...  
Keyword(s):  
Climate Change ◽  
Ozone Concentration ◽  
General Circulation ◽  
Climate Model ◽  
Transport Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
The Arctic

Abstract. The ozone chemistry over three centuries has been simulated based on climate prediction from a global climate model and constant anthropogenic emissions in order to separate out the effects on air pollution from climate change. Four decades in different centuries has been simulated using the chemistry version of the atmospheric long-range transport model; the Danish Eulerian Hemispheric Model (DEHM) forced with meteorology predicted by the ECHAM5/MPI-OM coupled Atmosphere-Ocean General Circulation Model. The largest changes in both meteorology, ozone and its precursors is found in the 21st century, however, also significant changes are found in the 22nd century. At surface level the ozone concentration is predicted to increase due to climate change in the areas where substantial amounts of ozone precursors are emitted. Elsewhere a significant decrease is predicted at the surface. In the free troposphere a general increase is found in the entire Northern Hemisphere except in the tropics, where the ozone concentration is decreasing. In the Arctic the ozone concentration will increase in the entire air column, which most likely is due to changes in transport. The change in temperature, humidity and the naturally emitted Volatile Organic Compounds (VOCs) are governing with respect to changes in ozone both in the past, present and future century.

scholarly journals Mid-Pliocene global climate simulation with MRI-CGCM2.3: set-up and initial results of PlioMIP Experiments 1 and 2

2012 ◽  
Vol 5 (3) ◽  
pp. 793-808 ◽  
Author(s):  
Y. Kamae ◽  
H. Ueda
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Climate Simulation ◽  
Polar Regions ◽  
The North ◽  
Set Up

Abstract. The mid-Pliocene (3.3 to 3.0 million yr ago), a globally warm period before the Quaternary, is recently attracting attention as a new target for paleoclimate modelling and data-model synthesis. This paper reports set-ups and results of experiments proposed in Pliocene Model Intercomparison Project (PlioMIP) using a global climate model, MRI-CGCM2.3. We conducted pre-industrial and mid-Pliocene runs by using the coupled atmosphere-ocean general circulation model (AOGCM) and its atmospheric component (AGCM) for the PlioMIP Experiments 2 and 1, respectively. In addition, we conducted two types of integrations in AOGCM simulation, with and without flux adjustments on sea surface. General characteristics of differences in the simulated mid-Pliocene climate relative to the pre-industrial in the three integrations are compared. In addition, patterns of predicted mid-Pliocene biomes resulting from the three climate simulations are compared in this study. Generally, difference of simulated surface climate between AGCM and AOGCM is larger than that between the two AOGCM runs, with and without flux adjustments. The simulated climate shows different pattern between AGCM and AOGCM particularly over low latitude oceans, subtropical land regions and high latitude oceans. The AOGCM simulations do not reproduce wetter environment in the subtropics relative to the present-day, which is suggested by terrestrial proxy data. The differences between the two types of AOGCM runs are small over the land, but evident over the ocean particularly in the North Atlantic and polar regions.

scholarly journals A Framework for Interpreting Regularized State Estimation

2014 ◽  
Vol 142 (1) ◽  
pp. 386-400 ◽  
Author(s):  
Nozomi Sugiura ◽  
Shuhei Masuda ◽  
Yosuke Fujii ◽  
Masafumi Kamachi ◽  
Yoichi Ishikawa ◽  
...  
Keyword(s):  
State Estimation ◽  
General Circulation ◽  
Optimization Problem ◽  
Chaotic Systems ◽  
Initial Conditions ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Vertical Diffusion ◽  
Reference Time

Abstract Four-dimensional variational data assimilation (4D-Var) on a seasonal-to-interdecadal time scale under the existence of unstable modes can be viewed as an optimization problem of synchronized, coupled chaotic systems. The problem is tackled by adjusting initial conditions to bring all stable modes closer to observations and by using a continuous guide to direct unstable modes toward a reference time series. This interpretation provides a consistent and effective procedure for solving problems of long-term state estimation. By applying this approach to an ocean general circulation model with a parameterized vertical diffusion procedure, it is demonstrated that tangent linear and adjoint models in this framework should have no unstable modes and hence be suitable for tracking persistent signals. This methodology is widely applicable to extend the assimilation period in 4D-Var.

scholarly journals FORTE 2.0: a fast, parallel and flexible coupled climate model

2021 ◽  
Vol 14 (1) ◽  
pp. 275-293
Author(s):  
Adam T. Blaker ◽  
Manoj Joshi ◽  
Bablu Sinha ◽  
David P. Stevens ◽  
Robin S. Smith ◽  
...  
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Ocean Model ◽  
Coupled Climate Model ◽  
Layer Depth ◽  
Ocean General Circulation ◽  
Modular Ocean Model

Abstract. FORTE 2.0 is an intermediate-resolution coupled atmosphere–ocean general circulation model (AOGCM) consisting of the Intermediate General Circulation Model 4 (IGCM4), a T42 spectral atmosphere with 35σ layers, coupled to Modular Ocean Model – Array (MOMA), a 2∘ × 2∘ ocean with 15 z-layer depth levels. Sea ice is represented by a simple flux barrier. Both the atmosphere and ocean components are coded in Fortran. It is capable of producing a stable climate for long integrations without the need for flux adjustments. One flexibility afforded by the IGCM4 atmosphere is the ability to configure the atmosphere with either 35σ layers (troposphere and stratosphere) or 20σ layers (troposphere only). This enables experimental designs for exploring the roles of the troposphere and stratosphere, and the faster integration of the 20σ layer configuration enables longer duration studies on modest hardware. A description of FORTE 2.0 is given, followed by the analysis of two 2000-year control integrations, one using the 35σ configuration of IGCM4 and one using the 20σ configuration.

scholarly journals Large-basin hydrological response to climate model outputs: uncertainty caused by the internal atmospheric variability

2015 ◽  
Vol 12 (2) ◽  
pp. 2305-2348 ◽  
Author(s):  
A. Gelfan ◽  
V. A. Semenov ◽  
E. Gusev ◽  
Y. Motovilov ◽  
O. Nasonova ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Initial Conditions ◽  
Lower Boundary ◽  
Circulation Model ◽  
The Arctic ◽  
Hydrological Models ◽  
Atmospheric Variability ◽  
Ensemble Simulations ◽  
The Mean

Abstract. An approach is proposed to assess hydrological simulation uncertainty originating from internal atmospheric variability. The latter is one of three major factors contributing to the uncertainty of simulated climate change projections (along with so-called "forcing" and "climate model" uncertainties). Importantly, the role of the internal atmospheric variability is the most visible over the spatial–temporal scales of water management in large river basins. The internal atmospheric variability is represented by large ensemble simulations (45 members) with the ECHAM5 atmospheric general circulation model. The ensemble simulations are performed using identical prescribed lower boundary conditions (observed sea surface temperature, SST, and sea ice concentration, SIC, for 1979–2012) and constant external forcing parameters but different initial conditions of the atmosphere. The ensemble of the bias-corrected ECHAM5-outputs as well as ensemble averaged ECHAM5-output are used as the distributed input for ECOMAG and SWAP hydrological models. The corresponding ensembles of runoff hydrographs are calculated for two large rivers of the Arctic basin: the Lena and the Northern Dvina rivers. A number of runoff statistics including the mean and the SD of the annual, monthly and daily runoff, as well as the annual runoff trend are assessed. The uncertainties of runoff statistics caused by the internal atmospheric variability are estimated. It is found that the uncertainty of the mean and SD of the runoff has a distinguished seasonal dependence with maximum during the periods of spring-summer snowmelt and summer-autumn rainfall floods. A noticeable non-linearity of the hydrological models' response to the ensemble ECHAM5 output is found most strongly expressed for the Northern Dvine River basin. It is shown that the averaging over ensemble members effectively filters stochastic term related to internal atmospheric variability. The simulated trends are close to normally distributed around ensemble mean value that indicates that a considerable portion of the observed trend can be externally driven.

scholarly journals The Atmosphere-Ocean General Circulation Model EMAC-MPIOM

2011 ◽  
Vol 4 (3) ◽  
pp. 771-784 ◽  
Author(s):  
A. Pozzer ◽  
P. Jöckel ◽  
B. Kern ◽  
H. Haak
Keyword(s):  
General Circulation Model ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Coupling Method ◽  
Model Systems ◽  
Time Performance ◽  
Ocean General Circulation ◽  
Run Time

Abstract. The ECHAM/MESSy Atmospheric Chemistry (EMAC) model is coupled to the ocean general circulation model MPIOM using the Modular Earth Submodel System (MESSy) interface. MPIOM is operated as a MESSy submodel, thus the need of an external coupler is avoided. The coupling method is tested for different model configurations, proving to be very flexible in terms of parallel decomposition and very well load balanced. The run-time performance analysis and the simulation results are compared to those of the COSMOS (Community earth System MOdelS) climate model, using the same configurations for the atmosphere and the ocean in both model systems. It is shown that our coupling method shows a comparable run-time performance to the coupling based on the OASIS (Ocean Atmosphere Sea Ice Soil, version 3) coupler. The standard (CMIP3) climate model simulations performed with EMAC-MPIOM show that the results are comparable to those of other Atmosphere-Ocean General Circulation models.

scholarly journals Reproducibility of Seasonal Land Surface Climate

2006 ◽  
Vol 7 (1) ◽  
pp. 114-136 ◽  
Author(s):  
Thomas J. Phillips
Keyword(s):  
Land Surface ◽  
Seasonal Cycle ◽  
General Circulation ◽  
Climate Model ◽  
Initial Conditions ◽  
Southern Oscillation ◽  
Circulation Model ◽  
Seasonal Prediction ◽  
Climate Simulation ◽  
Continental Climate

Abstract In this study, the sensitivity of the continental seasonal climate to initial conditions is estimated from an ensemble of decadal simulations of an atmospheric general circulation model with the same specifications of radiative forcings and monthly ocean boundary conditions, but with different initial states of atmosphere and land. As measures of the “reproducibility” of continental climate for different initial conditions, spatiotemporal correlations are computed across paired realizations of 11 model land surface variables in which the seasonal cycle is either included or excluded—the former case being pertinent to climate simulation and the latter to seasonal prediction. It is found that the land surface variables that include the seasonal cycle are impacted only marginally by changes in initial conditions; moreover, their seasonal climatologies exhibit high spatial reproducibility. In contrast, the reproducibility of a seasonal land surface anomaly is generally low, although it is substantially higher in the Tropics; its spatial reproducibility also markedly fluctuates in tandem with warm and cold phases of the El Niño–Southern Oscillation. However, the overall degree of reproducibility depends on the particular land surface anomaly considered. It is also shown that the predictability of a land surface anomaly implied by its reproducibility statistics is consistent with what is inferred from more conventional predictability metrics. Implications of these results for climate model intercomparison projects and for operational forecasts of seasonal continental climate also are elaborated.

scholarly journals The simulation of Antarctic sea ice in the Hadley Centre Climate Model (HadCM3)

2001 ◽  
Vol 33 ◽  
pp. 585-591 ◽  
Author(s):  
John Turner ◽  
William Connolley ◽  
Doug Cresswell ◽  
Steven Harangozo
Keyword(s):  
Sea Ice ◽  
Satellite Data ◽  
General Circulation ◽  
Climate Model ◽  
Phase Error ◽  
Regional Scale ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Atmospheric Flow ◽  
Antarctic Sea Ice

AbstractAn assessment is presented of the extent and variability of Antarctic sea ice in the non-flux-corrected version of the Hadley Centre’s coupled atmosphere-ocean general circulation model (HadCM3). The results are based on a 100 year segment of a long control run of the model with the sea ice being compared to ice extents and concentrations derived from passive microwave satellite data. Over the year as a whole, the model ice extent (the area with >15% ice concentration) is 91% of that determined from satellite imagery, but, not surprisingly, the regional-scale distribution differs from the observed. Throughout the year there is too much ice near 90° E, which is believed to be present as a result of incorrect ocean currents near Kerguelen. In contrast to the satellite data, there is too little ice to the west of the Antarctic Peninsula as a result of anomalously northerly atmospheric flow, compared to observations. During the winter the sea-ice concentrations in the model are too high, possibly as a result of the simple representation of the sea ice, which does not simulate complex dynamical interactions within the pack. The annual cycle of sea-ice advance/retreat in the model has a phase error, with the winter sea-ice maximum extent being too late by about 1 month.

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