scholarly journals Reservoir Computing as a Tool for Climate Predictability Studies

2021 ◽  
Author(s):  
Balasubramanya Nadiga
Keyword(s):  
Dynamical Behavior ◽  
Earth System Model ◽  
System Model ◽  
Reference Trajectory ◽  
Reservoir Computing ◽  
Earth System ◽  
Full System ◽  
Climate Predictability ◽  
The North ◽  
Predictive Skill

<p>  Reduced-order dynamical models play a central role in developing our<br>  understanding of predictability of climate irrespective of whether<br>  we are dealing with the actual climate system or surrogate climate<br>  models. In this context, the Linear Inverse Modeling (LIM) approach,<br>  by helping capture a few essential interactions between dynamical<br>  components of the full system, has proven valuable in being able to<br>  provide insights into the dynamical behavior of the full system.</p><p>  We demonstrate that Reservoir Computing (RC), a form of machine<br>  learning suited for learning in the context of chaotic dynamics,<br>  provides an alternative nonlinear approach that improves on the LIM<br>  approach. We do this in the example setting of predicting sea<br>  surface temperature in the North Atlantic in the pre-industrial<br>  control simulation of a popular earth system model, the Community<br>  Earth System Model version 2 (CESM2) so that we can compare the<br>  performance of the new RC based approach with the traditional LIM<br>  approach both when learning data is plentiful and when such data is<br>  more limited. The useful predictive skill of the RC approach over a<br>  wider range of conditions---larger number of retained EOF<br>  coefficients, extending well into the limited data regime,<br>  etc.---suggests that this machine learning approach may have a use<br>  in climate predictability studies. While the possibility of<br>  developing a climate emulator---the ability to continue the<br>  evolution of the system on the attractor long after failing to be<br>  able to track the reference trajectory---is demonstrated in context<br>  of the Lorenz-63 system, it is suggested that further development of<br>  the RC approach may permit such uses of the new approach in settings<br>  of relevance to realistic predictability studies.</p>

scholarly journals Simulations of the mid-Pliocene Warm Period using two versions of the NASA/GISS ModelE2-R Coupled Model

2013 ◽  
Vol 6 (2) ◽  
pp. 517-531 ◽  
Author(s):  
M. A. Chandler ◽  
L. E. Sohl ◽  
J. A. Jonas ◽  
H. J. Dowsett ◽  
M. Kelley
Keyword(s):  
North Atlantic ◽  
Earth System Model ◽  
Warm Period ◽  
System Model ◽  
Earth System ◽  
Climate Control ◽  
Substantial Impact ◽  
The North ◽  
Future Global Warming ◽  
The North Atlantic

Abstract. The mid-Pliocene Warm Period (mPWP) bears many similarities to aspects of future global warming as projected by the Intergovernmental Panel on Climate Change (IPCC, 2007). Both marine and terrestrial data point to high-latitude temperature amplification, including large decreases in sea ice and land ice, as well as expansion of warmer climate biomes into higher latitudes. Here we present our most recent simulations of the mid-Pliocene climate using the CMIP5 version of the NASA/GISS Earth System Model (ModelE2-R). We describe the substantial impact associated with a recent correction made in the implementation of the Gent-McWilliams ocean mixing scheme (GM), which has a large effect on the simulation of ocean surface temperatures, particularly in the North Atlantic Ocean. The effect of this correction on the Pliocene climate results would not have been easily determined from examining its impact on the preindustrial runs alone, a useful demonstration of how the consequences of code improvements as seen in modern climate control runs do not necessarily portend the impacts in extreme climates. Both the GM-corrected and GM-uncorrected simulations were contributed to the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Many findings presented here corroborate results from other PlioMIP multi-model ensemble papers, but we also emphasise features in the ModelE2-R simulations that are unlike the ensemble means. The corrected version yields results that more closely resemble the ocean core data as well as the PRISM3D reconstructions of the mid-Pliocene, especially the dramatic warming in the North Atlantic and Greenland-Iceland-Norwegian Sea, which in the new simulation appears to be far more realistic than previously found with older versions of the GISS model. Our belief is that continued development of key physical routines in the atmospheric model, along with higher resolution and recent corrections to mixing parameterisations in the ocean model, have led to an Earth System Model that will produce more accurate projections of future climate.

scholarly journals Full-field initialized decadal predictions with the MPI earth system model: an initial shock in the North Atlantic

2017 ◽  
Vol 51 (7-8) ◽  
pp. 2593-2608 ◽  
Author(s):  
Jürgen Kröger ◽  
Holger Pohlmann ◽  
Frank Sienz ◽  
Jochem Marotzke ◽  
Johanna Baehr ◽  
...  
Keyword(s):  
North Atlantic ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Full Field ◽  
The North ◽  
Initial Shock ◽  
The North Atlantic ◽  
Decadal Predictions

scholarly journals Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity

2009 ◽  
Vol 5 (4) ◽  
pp. 2019-2051 ◽  
Author(s):  
T. Friedrich ◽  
A. Timmermann ◽  
O. Timm ◽  
A. Mouchet ◽  
D. M. Roche
Keyword(s):  
North Atlantic ◽  
Earth System Model ◽  
System Model ◽  
Hudson Bay ◽  
Earth System ◽  
Overturning Circulation ◽  
Intermediate Complexity ◽  
The North ◽  
The North Atlantic ◽  
Millennial Scale

Abstract. The effect of orbital variations on simulated millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) is studied using the earth system model of intermediate complexity LOVECLIM. It is found that for present-day topographic boundary conditions low obliquity values (~22.1°) favor the triggering of internally generated millennial-scale variability in the North Atlantic region. Reducing the obliquity leads to changes of the pause-pulse ratio of the corresponding AMOC oscillations. Stochastic excitations of the density-driven overturning circulation in the Nordic Seas can create regional sea-ice anomalies and a subsequent reorganization of the atmospheric circulation. The resulting remote atmospheric anomalies over the Hudson Bay can release freshwater pulses into the Labrador Sea leading to a subsequent reduction of convective activity. The millennial-scale AMOC oscillations disappear if LGM bathymetry (with closed Hudson Bay) is prescribed. Furthermore, our study documents the marine and terrestrial carbon cycle response to millennial-scale AMOC variability. Our model results support the notion that stadial regimes in the North Atlantic are accompanied by relatively high levels of oxygen in thermocline and intermediate waters off California – in agreement with paleo-proxy data.

scholarly journals The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years

2019 ◽  
Author(s):  
Anne Dallmeyer ◽  
Martin Claussen ◽  
Stephan J. Lorenz ◽  
Timothy Shanahan
Keyword(s):  
Summer Monsoon ◽  
Model Simulation ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Mean Flow ◽  
Western Sahara ◽  
The North ◽  
The Impact ◽  
Humid Period

Abstract. Enhanced summer insolation during the early and mid-Holocene drove increased precipitation and widespread expansion of vegetation across the Sahara during the African Humid Period (AHP). While changes in atmospheric dynamics during this time have been a major focus of palaeoclimate modelling efforts, the transient nature of the shift back to the modern desert state at the end of this period is less well understood. Reconstructions reveal a spatially and temporally complex end of the AHP, with an earlier end in the north than in the south and in the east than in the west. Some records suggest a rather abrupt end, whereas others indicate a gradual decline in moisture availability. Here we investigate the end of the AHP based on a transient simulation of the last 7850 years with the comprehensive Earth System Model MPI-ESM1.2. The model largely reproduces the time-transgressive end of the AHP evident in proxy data, and indicates that it is due to the regionally varying dynamical controls on precipitation. The impact of the main rain-bringing systems, i.e. the summer monsoon and extratropical troughs, varies spatially, leading to heterogeneous seasonal rainfall cycles that impose regionally different responses to the Holocene insolation decrease. An increase in extratropical troughs that interact with the tropical mean flow and transport moisture to the Western Sahara during mid-Holocene delays the end of the AHP in that region. Along the coast, this interaction maintains humid conditions for a longer time than further inland. Drying in this area occurs when this interaction becomes too weak to sustain precipitation. In the lower latitudes of West Africa, where the rainfall is only influenced by the summer monsoon dynamics, the end of the AHP coincides with the retreat of the monsoonal rainbelt. The model results clearly demonstrate that non-monsoonal dynamics can also play an important role in forming the precipitation signal and should therefore not be neglected in analyses of North African rainfall trends.

scholarly journals The Brazilian Earth System Model ocean–atmosphere (BESM-OA) version 2.5: evaluation of its CMIP5 historical simulation

2019 ◽  
Vol 12 (4) ◽  
pp. 1613-1642 ◽  
Author(s):  
Sandro F. Veiga ◽  
Paulo Nobre ◽  
Emanuel Giarolla ◽  
Vinicius Capistrano ◽  
Manoel Baptista Jr. ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Earth System Model ◽  
Meridional Overturning Circulation ◽  
System Model ◽  
Historical Period ◽  
Earth System ◽  
Historical Simulation ◽  
The North ◽  
Ocean Atmosphere

Abstract. The performance of the coupled ocean–atmosphere component of the Brazilian Earth System Model version 2.5 (BESM-OA2.5) was evaluated in simulating the historical period 1850–2005. After a climate model validation procedure in which the main atmospheric and oceanic variabilities were evaluated against observed and reanalysis datasets, the evaluation specifically focused on the mean climate state and the most important large-scale climate variability patterns simulated in the historical run, which was forced by the observed greenhouse gas concentration. The most significant upgrades in the model's components are also briefly presented here. BESM-OA2.5 could reproduce the most important large-scale variabilities, particularly over the Atlantic Ocean (e.g., the North Atlantic Oscillation, the Atlantic Meridional Mode, and the Atlantic Meridional Overturning Circulation), and the extratropical modes that occur in both hemispheres. The model's ability to simulate such large-scale variabilities supports its usefulness for seasonal climate prediction and in climate change studies.

scholarly journals The Modeling of the North Equatorial Countercurrent in the Community Earth System Model and its Oceanic Component

2019 ◽  
Vol 11 (2) ◽  
pp. 531-544 ◽  
Author(s):  
Zhikuo Sun ◽  
Hailong Liu ◽  
Pengfei Lin ◽  
Yu‐heng Tseng ◽  
Justin Small ◽  
...  
Keyword(s):  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
The North ◽  
Community Earth System Model

scholarly journals The end of the African humid period as seen by a transient comprehensive Earth system model simulation of the last 8000 years

2020 ◽  
Vol 16 (1) ◽  
pp. 117-140 ◽  
Author(s):  
Anne Dallmeyer ◽  
Martin Claussen ◽  
Stephan J. Lorenz ◽  
Timothy Shanahan
Keyword(s):  
Summer Monsoon ◽  
Model Simulation ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Mean Flow ◽  
Western Sahara ◽  
The North ◽  
The Impact ◽  
Humid Period

Abstract. Enhanced summer insolation during the early and mid-Holocene drove increased precipitation and widespread expansion of vegetation across the Sahara during the African humid period (AHP). While changes in atmospheric dynamics during this time have been a major focus of palaeoclimate modelling efforts, the transient nature of the shift back to the modern desert state at the end of this period is less well understood. Reconstructions reveal a spatially and temporally complex end of the AHP, with an earlier end in the north than in the south and in the east than in the west. Some records suggest a rather abrupt end, whereas others indicate a gradual decline in moisture availability. Here we investigate the end of the AHP based on a transient simulation of the last 7850 years with the comprehensive Earth system model MPI-ESM1.2. The model largely reproduces the time-transgressive end of the AHP evident in proxy data, and it indicates that it is due to the regionally varying dynamical controls on precipitation. The impact of the main rain-bringing systems, i.e. the summer monsoon and extratropical troughs, varies spatially, leading to heterogeneous seasonal rainfall cycles that impose regionally different responses to the Holocene insolation decrease. An increase in extratropical troughs that interact with the tropical mean flow and transport moisture to the western Sahara during the mid-Holocene delays the end of the AHP in that region. Along the coast, this interaction maintains humid conditions for a longer time than further inland. Drying in this area occurs when this interaction becomes too weak to sustain precipitation. In the lower latitudes of west Africa, where the rainfall is only influenced by the summer monsoon dynamics, the end of the AHP coincides with the retreat of the monsoonal rain belt. The model results clearly demonstrate that non-monsoonal dynamics can also play an important role in forming the precipitation signal and should therefore not be neglected in analyses of north African rainfall trends.

scholarly journals The Brazilian Earth System Model version 2.5: Evaluation of its CMIP5 historical simulation

2018 ◽  
Author(s):  
Sandro F. Veiga ◽  
Paulo Nobre ◽  
Emanuel Giarolla ◽  
Vinicius Capistrano ◽  
Manoel Baptista Jr. ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Earth System Model ◽  
Meridional Overturning Circulation ◽  
System Model ◽  
Historical Period ◽  
Earth System ◽  
Historical Simulation ◽  
Model Version ◽  
The North

Abstract. The performance of the coupled ocean-atmosphere component of the Brazilian Earth System Model version 2.5 (BESM-OA2.5) simulating the historical period 1850–2005 is evaluated. Following climate model validation procedure, in which the atmospheric and oceanic main variabilities are validated against observation and Reanalysis datasets, the evaluation particularly focuses the mean climate state and the most important large-scale climate variability patterns simulated in the historical run, which is forced by observed greenhouse gas concentration. The most significant upgrades in the model’s components are also presented briefly. BESM-OA2.5 is able to reproduce the most important large-scale variabilities, particularly over the Atlantic (e.g. the North Atlantic Oscillation, the Atlantic Meridional Mode and the Atlantic Meridional Overturning Circulation) and the extratropical modes that occur in both hemispheres. The model's ability in simulating large-scale variabilities indicates its usefulness for seasonal climate prediction and climate change studies.

scholarly journals Internally generated millennial-scale climate variability in an earth system model of intermediate complexity: sensitivity to ocean bathymetry and orbital forcing

2010 ◽  
Vol 3 (1) ◽  
pp. 273-307
Author(s):  
T. Friedrich ◽  
A. Timmermann ◽  
L. Menviel ◽  
O. Timm ◽  
A. Mouchet ◽  
...  
Keyword(s):  
Earth System Model ◽  
Meridional Overturning Circulation ◽  
System Model ◽  
Hudson Bay ◽  
Earth System ◽  
Overturning Circulation ◽  
Intermediate Complexity ◽  
The North ◽  
Stochastic Excitations ◽  
Millennial Scale

Abstract. The effect of orbital variations on simulated millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) is studied using the earth system model of intermediate complexity LOVECLIM. It is found that for present-day topographic boundary conditions low obliquity values (~22.1°) favor the triggering of internally generated millennial-scale variability in the North Atlantic region. Reducing the obliquity leads to changes of the pause-pulse ratio of the corresponding AMOC oscillations. Stochastic excitations of the density-driven overturning circulation in the Nordic Seas can create regional sea-ice anomalies and a subsequent reorganization of the atmospheric circulation. The resulting remote atmospheric anomalies over the Hudson Bay can release freshwater pulses into the Labrador Sea leading to a subsequent reduction of convective activity. The millennial-scale AMOC oscillations disappear if LGM bathymetry (with closed Hudson Bay) or Hudson Bay salinity is prescribed. Furthermore, our study documents the marine and terrestrial carbon cycle response to millennial-scale AMOC variability.

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