A global ensemble-based comparison of the last two glacial inceptions with LCice 2.0

2020 ◽  
Author(s):  
Marilena Geng ◽  
Lev Tarasov ◽  
Taimaz Bahadory
Keyword(s):  
Climate Model ◽  
Ice Sheet ◽  
Test Case ◽  
Glacial Cycles ◽  
Systems Model ◽  
External Forcings ◽  
Transient Simulations ◽  
Spatio Temporal ◽  
Global Mean Sea Level ◽  
Fully Coupled

<p>What determines the character of glacial inceptions? Does the spatio-temporal pattern of ice nucleation and expansion vary much between Late Pleistocene glacial inceptions? According to various benthic del18O stacks, the MIS 7 interglacial was the most anomalous in character of the last 4 interglacials. Key differences include a weaker interglacial state and an initial fast inception interrupted by a return to a similar and extended interglacial state. These anomalies of MIS 7 along with temporal proximity arguably make the last two glacial inceptions the best test case for addressing our opening questions. As part of a larger project to generate and analyze a data-constrained ensemble of fully coupled ice/climate transient simulations for the last two complete glacial cycles, herein we present initial results comparing the last two glacial inceptions (MIS 7 and 5d). We are using a new version of the fully coupled ice/climate model LCice. LCice now simulates all 4 paleo ice sheet complexes with hybrid shallow-shelf and shallow-ice physics. It has already been shown to capture northern hemispheric ice sheet growth and subsequent retreat consistent with inferences from global mean sea level proxies (Bahadory et al, 2019). Orbital and greenhouse gas changes are the only external forcings applied to the model. A 300 member ensemble probes parametric uncertainties in both the 3D Glacial Systems Model and LoveClim (Atmosphere/Ocean/Vegetation) components of LCice. Our presentation will compare the evolution and relative phasing of all 4 paleo ice sheets, and associated changes in the rest of the modelled climate system.</p>

Using Clustered Climate Regimes to Analyze and Compare Predictions from Fully Coupled General Circulation Models

2005 ◽  
Vol 9 (10) ◽  
pp. 1-27 ◽  
Author(s):  
Forrest M. Hoffman ◽  
William W. Hargrove ◽  
David J. Erickson ◽  
Robert J. Oglesby
Keyword(s):  
Time Series ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Terrestrial Ecosystems ◽  
General Circulation Models ◽  
Transient Simulations ◽  
Spatio Temporal ◽  
Earth’S Climate ◽  
Fully Coupled

Abstract Changes in Earth’s climate in response to atmospheric greenhouse gas buildup impact the health of terrestrial ecosystems and the hydrologic cycle. The environmental conditions influential to plant and animal life are often mapped as ecoregions, which are land areas having similar combinations of environmental characteristics. This idea is extended to establish regions of similarity with respect to climatic characteristics that evolve through time using a quantitative statistical clustering technique called Multivariate Spatio-Temporal Clustering (MSTC). MSTC was applied to the monthly time series output from a fully coupled general circulation model (GCM) called the Parallel Climate Model (PCM). Results from an ensemble of five 99-yr Business-As-Usual (BAU) transient simulations from 2000 to 2098 were analyzed. MSTC establishes an exhaustive set of recurring climate regimes that form a “skeleton” through the “observations” (model output) throughout the occupied portion of the climate phase space formed by the characteristics being considered. MSTC facilitates direct comparison of ensemble members and ensemble and temporal averages since the derived climate regimes provide a basis for comparison. Moreover, by mapping all land cells to discrete climate states, the dynamic behavior of any part of the system can be studied by its time-varying sequence of climate state occupancy. MSTC is a powerful tool for model developers and environmental decision makers who wish to understand long, complex time series predictions of models. Strong predicted interannual trends were revealed in this analysis, including an increase in global desertification; a decrease in the cold, dry high-latitude conditions typical of North American and Asian winters; and significant warming in Antarctica and western Greenland.

scholarly journals PARASO, a circum-Antarctic fully-coupled ice-sheet - ocean - sea-ice - atmosphere - land model involving f.ETISh1.7, NEMO3.6, LIM3.6, COSMO5.0 and CLM4.5

2021 ◽  
Author(s):  
Charles Pelletier ◽  
Thierry Fichefet ◽  
Hugues Goosse ◽  
Konstanze Haubner ◽  
Samuel Helsen ◽  
...  
Keyword(s):  
Sea Ice ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Sheet ◽  
Horizontal Resolution ◽  
Fine Tuning ◽  
Polar Regions ◽  
Surface Mass ◽  
The Impact ◽  
Fully Coupled

Abstract. We introduce PARASO, a novel five-component fully-coupled regional climate model over an Antarctic circumpolar domain covering the full Southern Ocean. The state-of-the-art models used are f.ETISh1.7 (ice sheet), NEMO3.6 (ocean), LIM3.6 (sea ice), COSMO5.0 (atmosphere) and CLM4.5 (land), which are here run at an horizontal resolution close to 1/4°. One key-feature of this tool resides in a novel two-way coupling interface for representing ocean – ice-sheet interactions, through explicitly resolved ice-shelf cavities. The impact of atmospheric processes on the Antarctic ice sheet is also conveyed through computed COSMO-CLM – f.ETISh surface mass exchanges. In this technical paper, we briefly introduce each model's configuration and document the developments that were carried out in order to establish PARASO. The new offline-based NEMO – f.ETISh coupling interface is thoroughly described. Our developments also include a new surface tiling approach to combine open-ocean and sea-ice covered cells within COSMO, which was required to make this model relevant in the context of coupled simulations in polar regions. We present results from a 2000–2001 coupled two-year experiment. PARASO is numerically stable and fully operational. The 2-year simulation conducted without fine tuning of the model reproduced the main expected features, although remaining systematic biases provide perspectives for further adjustment and development.

scholarly journals A seasonal energy-balance climate model for coupling to ice-sheet models

1996 ◽  
Vol 23 ◽  
pp. 174-180 ◽  
Author(s):  
André Paul
Keyword(s):  
Energy Balance ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Water Flux ◽  
Computational Cost ◽  
Ice Sheet ◽  
Test Case ◽  
Conservation Of Energy ◽  
Independent Variables ◽  
Fresh Water Flux

An energy-balance climate model designed for coupling to ice-sheet models is presented. Its independent variables are longitude, latitude and time of the year. The model is based on the vertically integrated equations of conservation of energy and humidity. It can predict the vertically averaged temperature. Since it includes a hydrological cycle, it can also diagnose the net fresh-water flux and hence the annual snow budget at the atmosphere–ice-sheet interface. To this end, the model does not require observed precipitation rates. The computational cost is reduced by using an analytically computed Fourier–Legendre representation of daily insolation. For a highly idealized test-case configuration, two simple sensitivity experiments are carried out.

OBLIMAP parallelization and optimization toward high resolution climate model - ice sheet model coupler

2021 ◽  
Author(s):  
Erwan Raffin ◽  
David Guibert ◽  
Thomas Reerink
Keyword(s):  
High Resolution ◽  
Shared Memory ◽  
Large Scale ◽  
Climate Model ◽  
Climate Modeling ◽  
Parallel Implementation ◽  
Ice Sheet ◽  
Adaptive Mesh ◽  
Test Case ◽  
Single Node

<p>Within the ESiWACE2 project we parallelized and optimized OBLIMAP. OBLIMAP is a climate model - ice sheet model coupler that can be used for offline and online coupling with embeddable mapping routines. In order to anticipate future demand concerning higher resolution and/or adaptive mesh applications, a parallel implementation of OBLIMAP's fortran code with MPI has been developed. The data intense nature of this mapping task, required a shared memory approach across the processors per compute node in order to prevent that the node memory is the limiting bottleneck. Besides, the current parallel implementation allows multi node scaling and includes parallel netcdf IO in addition with loop optimizations. Results show that the new parallel implementation offers better performance and scales well. On a single node, the shared memory approach allows now to use all the available cores, up to 128 cores in our experiments on Antarctica 20x20km test case where the original code was limited to 64 cores on this high-end node and it was even limited to 8 cores on moderate platforms. The multi node parallelization offers on Greenland 2x2km test case a speedup of 4.4x on 4 high-end compute nodes equipped with 128 cores each compared to the original code which was able to run only on 1 node. This paves the way to the establishment of OBLIMAP as an candidate ice sheet coupling library candidate for large-scale, high-resolution climate modeling.</p>

A Gaussian process emulator for simulating ice sheet-climate interactions on a multi-million year timescale

2020 ◽  
Author(s):  
Jonas Van Breedam ◽  
Philippe Huybrechts ◽  
Michel Crucifix
Keyword(s):  
Gaussian Process ◽  
Climate Model ◽  
Ice Sheet ◽  
Climate System ◽  
Lapse Rate ◽  
Coupled Models ◽  
Climate Interactions ◽  
Coupling Time ◽  
Fully Coupled ◽  
Gaussian Process Emulator

<p>Fully coupled state-of-the-art Atmosphere-Ocean General Circulation Models are the best tool to investigate feedbacks between the different components of the climate system on a decadal to centennial timescale. On millennial to multi-millennial timescales, Earth System Models of Intermediate Complexity are used to explore the feedbacks in the climate system between the ice sheets, the atmosphere and the ocean. Those fully coupled models, even at coarser resolution, are computationally very expensive and other techniques have been proposed to simulate ice sheet-climate interactions on a million-year timescale. The asynchronous coupling technique proposes to run a climate model for a few decades and subsequently an ice sheet model for a few millennia. Another, more efficient method is the use of a matrix look-up table where climate model runs are performed for end-members and intermediate climatic states are linearly interpolated.</p><p>In this study, a novel coupling approach is presented where a Gaussian Process emulator applied to the climate model HadSM3 is coupled to the ice sheet model AISMPALEO. We have tested the sensitivity of the formulation of the ice sheet parameter and of the coupling time to the evolution of the ice sheet over time. Additionally, we used different lapse rate adjustments between the relatively coarse climate model and the much finer ice sheet model topography. It is shown that the ice sheet evolution over a million year timescale is strongly sensitive to the choice of the coupling time and to the implementation of the lapse rate adjustment. With the new coupling procedure, we provide a more realistic and computationally efficient framework for ice sheet-climate interactions on a multi-million year timescale.</p><p> </p>

scholarly journals Coupling the Glacial Systems Model (GSM) to LOVECLIM: description, sensitivities, and validation

2018 ◽  
Author(s):  
Taimaz Bahadory ◽  
Lev Tarasov
Keyword(s):  
Surface Temperature ◽  
Ice Sheet ◽  
Sheet Thickness ◽  
Coupled Model ◽  
Reanalysis Data ◽  
Glacial Cycles ◽  
Systems Model ◽  
Meltwater Runoff ◽  
Ongoing Work ◽  
Acceptance Range

Abstract. We have coupled an Earth Systems Model of Intermediate Complexity (LOVECLIM) to the Glacial Systems Model (GSM). This coupling includes a number of interactions between ice sheets and climate that are often ignored: dynamic meltwater runoff routing, novel down-scaling for precipitation that corrects orographic forcing to the higher resolution ice sheet grid (advective precipitation), dynamic vertical temperature gradient, and ocean temperatures for sub-shelf melt. The sensitivity of the coupled model with respect to the selected parameterizations and coupling schemes is investigated. Each new coupling feature has a significant impact on ice sheet evolution. An ensemble of runs is used to explore the behaviour of the coupled model over a set of 2000 parameter vectors using Present-Day (PD) initial and boundary conditions. The ensemble of coupled model runs is compared against PD reanalysis data for atmosphere (surface temperature, precipitation, jet-stream and Rossby number of jet), ocean (sea ice, sea surface temperature, and AMOC), and Northern Hemisphere ice sheet thickness and extent. The parameter vectors are then narrowed by rejecting model runs (1700 CE to present) with regional land ice volume changes beyond an acceptance range. The selected sub-set forms the basis for ongoing work to explore the spatial-temporal phase space of the last two glacial cycles.

Simulating Interactive Ice Sheets in the Multi-Resolution AWI-ESM: A case study using the SCOPE Coupler

2021 ◽  
Author(s):  
Paul Gierz ◽  
Lars Ackermann ◽  
Christian Rodehacke ◽  
Uta Krebs-Kanzow ◽  
Christian Stepanek ◽  
...  
Keyword(s):  
Climate Model ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Global Ocean ◽  
Earth System ◽  
Last Interglacial ◽  
Ice Shelf ◽  
Coupled Models ◽  
Fully Coupled ◽  
Paleoclimate Studies

<p>Interactions between the climate and the cryosphere have the potential to induce strong non-linear transitions in the Earth's climate. These interactions influence both the atmospheric circulation, by changing the ice sheet's geometry, as well as the oceanic circulation, by modification of the water mass properties. Furthermore, the waxing and waning of large continental ice sheets influences the global albedo, altering the energy balance of the Earth System and inducing climate-ice sheet feedbacks on a global scale as evident in Pleistocene glacial-interglacial cycles. To date, few fully<br>comprehensive models exist, that do not only contain a coupled atmosphere/land/ocean component, but also consider interactive cryosphere physics. Yet, on glacial-interglacial and tectonic time scales, as well as in the Anthropocene, ice sheets are not in equilibrium with the climate, and prescribed fixed ice sheet representations in the model can principally be only an approximation to reality. Only climate models, that contain interactive ice sheets, can produce simulations of the Earth's climate which include all feedbacks and processes related to atmosphere-land-ocean-ice interactions. Previous fully coupled models were limited either by low spatial resolution or an incomplete representation of ice sheet processes, such as iceberg calving, surface ablation processes, and ocean/ice-shelf interactions. Here, we present the newly developed AWI-Earth System Model (AWI-ESM), which tackles some of these problems. Our modelling toolbox is based on the AWI-climate model, including atmosphere and vegetation components suitable for paleoclimate studies, a multi-resolution global ocean component which can be refined to simulate regions of interest at high resolution, and an ice sheet component suitable for simulating both ice sheet and ice shelf dynamics and thermodynamics. We describe the currently implemented coupling between these components, present first results for the Mid-Holocene and Last Interglacial, and introduce further ideas for scientific applications for both future and past climate states with a focus on the Northern Hemisphere. Finally, we provide an outlook on the potential of such fully coupled Earth System models in improving representation of climate-ice sheet feedbacks in future paleoclimate studies with this model.</p>

scholarly journals Assessing spatio-temporal variability and trends in modelled and measured Greenland Ice Sheet albedo (2000–2013)

2014 ◽  
Vol 8 (6) ◽  
pp. 2293-2312 ◽  
Author(s):  
P. M. Alexander ◽  
M. Tedesco ◽  
X. Fettweis ◽  
R. S. W. van de Wal ◽  
C. J. P. P. Smeets ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Temporal Variability ◽  
Surface Albedo ◽  
Climate Model ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
High Elevation ◽  
In Situ Observations ◽  
Spatio Temporal

Abstract. Accurate measurements and simulations of Greenland Ice Sheet (GrIS) surface albedo are essential, given the role of surface albedo in modulating the amount of absorbed solar radiation and meltwater production. In this study, we assess the spatio-temporal variability of GrIS albedo during June, July, and August (JJA) for the period 2000–2013. We use two remote sensing products derived from data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS), as well as outputs from the Modèle Atmosphérique Régionale (MAR) regional climate model (RCM) and data from in situ automatic weather stations. Our results point to an overall consistency in spatio-temporal variability between remote sensing and RCM albedo, but reveal a difference in mean albedo of up to ~0.08 between the two remote sensing products north of 70° N. At low elevations, albedo values simulated by the RCM are positively biased with respect to remote sensing products by up to ~0.1 and exhibit low variability compared with observations. We infer that these differences are the result of a positive bias in simulated bare ice albedo. MODIS albedo, RCM outputs, and in situ observations consistently indicate a decrease in albedo of −0.03 to −0.06 per decade over the period 2003–2013 for the GrIS ablation area. Nevertheless, satellite products show a decline in JJA albedo of −0.03 to −0.04 per decade for regions within the accumulation area that is not confirmed by either the model or in situ observations. These findings appear to contradict a previous study that found an agreement between in situ and MODIS trends for individual months. The results indicate a need for further evaluation of high elevation albedo trends, a reconciliation of MODIS mean albedo at high latitudes, and the importance of accurately simulating bare ice albedo in RCMs.

scholarly journals Examining the stratospheric response to the solar cycle in a coupled WACCM simulation with an internally generated QBO

2014 ◽  
Vol 14 (10) ◽  
pp. 4843-4856 ◽  
Author(s):  
A. C. Kren ◽  
D. R. Marsh ◽  
A. K. Smith ◽  
P. Pilewskie
Keyword(s):  
Solar Cycle ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Strong Positive Correlation ◽  
Quasi Biennial Oscillation ◽  
External Forcings ◽  
Uv Irradiance ◽  
Transient Simulations ◽  
Uv Response ◽  
Model Components

Abstract. The response of the stratosphere to the combined interaction of the quasi-biennial oscillation (QBO) and the solar cycle in ultraviolet (UV) radiation, and the influence of the solar cycle on the QBO, are investigated using the Whole Atmosphere Community Climate Model (WACCM). Transient simulations were performed beginning in 1850 that included fully interactive ocean and chemistry model components, observed greenhouse gas concentrations, volcanic eruptions, and an internally generated QBO. Over the full length of the simulations we do not find a solar cycle modulation of either the QBO period or amplitude. We also do not find a persistent wintertime UV response in polar stratospheric geopotential heights when stratifying by the QBO phase. Over individual ~40 year periods of the simulation, a statistically significant correlation is sometimes found between the northern polar geopotential heights in February and UV irradiance during the QBO's westerly phase. However, the sign of the correlation varies over the simulation, and is never significant during the QBO's easterly phase. Complementing this is the analysis of four simulations using a QBO prescribed to match observations over the period 1953–2005. Again, no consistent correlation is evident. In contrast, over the same period, meteorological reanalysis shows a strong positive correlation during the QBO westerly phase, although it weakens as the period is extended. The results raise the possibility that the observed polar solar–QBO correlation may have occurred because of the relatively short data record and the presence of additional external forcings rather than a direct solar–QBO interaction.

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