scholarly journals Dynamical landscape and multistability of a climate model

2021 ◽  
Vol 477 (2250) ◽  
pp. 20210019
Author(s):  
Georgios Margazoglou ◽  
Tobias Grafke ◽  
Alessandro Laio ◽  
Valerio Lucarini
Keyword(s):  
Data Science ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Stable State ◽  
Snowball Earth ◽  
Ocean Heat Transport ◽  
Earth’S Climate ◽  
Transition Times ◽  
Basin Boundaries ◽  
Remarkable Agreement

We apply two independent data analysis methodologies to locate stable climate states in an intermediate complexity climate model and analyse their interplay. First, drawing from the theory of quasi-potentials, and viewing the state space as an energy landscape with valleys and mountain ridges, we infer the relative likelihood of the identified multistable climate states and investigate the most likely transition trajectories as well as the expected transition times between them. Second, harnessing techniques from data science, and specifically manifold learning, we characterize the data landscape of the simulation output to find climate states and basin boundaries within a fully agnostic and unsupervised framework. Both approaches show remarkable agreement, and reveal, apart from the well known warm and snowball earth states, a third intermediate stable state in one of the two versions of PLASIM, the climate model used in this study. The combination of our approaches allows to identify how the negative feedback of ocean heat transport and entropy production via the hydrological cycle drastically change the topography of the dynamical landscape of Earth’s climate.

scholarly journals Dynamical Landscape and Multistability of a Climate Model

2021 ◽  
Author(s):  
Georgios Margazoglou ◽  
Valerio Lucarini ◽  
Tobias Grafke ◽  
Alessandro Laio
Keyword(s):  
Data Science ◽  
Climate Models ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Stable State ◽  
Snowball Earth ◽  
Earth’S Climate ◽  
Transition Times ◽  
Basin Boundaries ◽  
Remarkable Agreement

<p>We apply two independent data analysis methodologies to locate stable climate states in an intermediate complexity climate model and analyze their interplay. First, drawing from the theory of quasipotentials, and viewing the state space as an energy landscape with valleys and mountain ridges, we infer the relative likelihood of the identified multistable climate states, and investigate the most likely transition trajectories as well as the expected transition times between them. Second, harnessing techniques from data science, specifically manifold learning, we characterize  the data landscape of the simulation output to find climate states and basin boundaries within a fully agnostic and unsupervised framework. Both approaches show remarkable agreement, and reveal, apart from the well known warm and snowball earth states, a third intermediate stable state in one of the two climate models we consider. The combination of our approaches allows to identify how the negative feedback of ocean heat transport and entropy production via the hydrological cycle drastically change the topography of the dynamical landscape of Earth's climate.</p>

scholarly journals Climate Determinism Revisited: Multiple Equilibria in a Complex Climate Model

2011 ◽  
Vol 24 (4) ◽  
pp. 992-1012 ◽  
Author(s):  
David Ferreira ◽  
John Marshall ◽  
Brian Rose
Keyword(s):  
Energy Balance ◽  
Sea Ice ◽  
Heat Transport ◽  
Ocean Circulation ◽  
General Circulation ◽  
Multiple Equilibria ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Ocean Heat Transport ◽  
Ice Cap

Abstract Multiple equilibria in a coupled ocean–atmosphere–sea ice general circulation model (GCM) of an aquaplanet with many degrees of freedom are studied. Three different stable states are found for exactly the same set of parameters and external forcings: a cold state in which a polar sea ice cap extends into the midlatitudes; a warm state, which is ice free; and a completely sea ice–covered “snowball” state. Although low-order energy balance models of the climate are known to exhibit intransitivity (i.e., more than one climate state for a given set of governing equations), the results reported here are the first to demonstrate that this is a property of a complex coupled climate model with a consistent set of equations representing the 3D dynamics of the ocean and atmosphere. The coupled model notably includes atmospheric synoptic systems, large-scale circulation of the ocean, a fully active hydrological cycle, sea ice, and a seasonal cycle. There are no flux adjustments, with the system being solely forced by incoming solar radiation at the top of the atmosphere. It is demonstrated that the multiple equilibria owe their existence to the presence of meridional structure in ocean heat transport: namely, a large heat transport out of the tropics and a relatively weak high-latitude transport. The associated large midlatitude convergence of ocean heat transport leads to a preferred latitude at which the sea ice edge can rest. The mechanism operates in two very different ocean circulation regimes, suggesting that the stabilization of the large ice cap could be a robust feature of the climate system. Finally, the role of ocean heat convergence in permitting multiple equilibria is further explored in simpler models: an atmospheric GCM coupled to a slab mixed layer ocean and an energy balance model.

scholarly journals Snowfall-albedo feedbacks could have led to deglaciation of snowball Earth starting from mid-latitudes

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Philipp de Vrese ◽  
Tobias Stacke ◽  
Jeremy Caves Rugenstein ◽  
Jason Goodman ◽  
Victor Brovkin
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Hydrological Cycle ◽  
High Surface ◽  
Dust Deposition ◽  
Carbon Dioxide Concentrations ◽  
Maximum Temperatures ◽  
Carbon Dioxide Levels ◽  
Earth’S Climate

AbstractSimple and complex climate models suggest a hard snowball – a completely ice-covered planet – is one of the steady-states of Earth’s climate. However, a seemingly insurmountable challenge to the hard-snowball hypothesis lies in the difficulty in explaining how the planet could have exited the glaciated state within a realistic range of atmospheric carbon dioxide concentrations. Here, we use simulations with the Earth system model MPI-ESM to demonstrate that terminal deglaciation could have been triggered by high dust deposition fluxes. In these simulations, deglaciation is not initiated in the tropics, where a strong hydrological cycle constantly regenerates fresh snow at the surface, which limits the dust accumulation and snow aging, resulting in a high surface albedo. Instead, comparatively low precipitation rates in the mid-latitudes in combination with high maximum temperatures facilitate lower albedos and snow dynamics that – for extreme dust fluxes – trigger deglaciation even at present-day carbon dioxide levels.

Implications of aerosol-induced snow darkening on regional hydroclimate over the Himalayas

2021 ◽  
Author(s):  
Vijayakumar Sivadasan Nair ◽  
Usha Keshav Hasyagar ◽  
Surendran Nair Suresh Babu
Keyword(s):  
South Asia ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Monsoon Season ◽  
Radiation Balance ◽  
Western Himalayas ◽  
Radiative Effect ◽  
Anthropogenic Aerosols ◽  
Snow Albedo ◽  
Snow Cover Extent

<p>The snow-covered mountains of Himalayas are known to play a crucial role in the hydrology of South Asia and are known as the “Asian water tower”. Despite the high elevations, the transport of anthropogenic aerosols from south Asia and desert dust from west Asia plays a significant role in directly and indirectly perturbing the radiation balance and hydrological cycle over the region. Absorbing aerosols like black carbon (BC) and dust deposited on the snow surface reduces the albedo of the Himalayan snow significantly (snow darkening or snow albedo effect). Using a Regional Climate Model (RegCM-4.6.0) coupled with SNow, ICe and Aerosol Radiation (SNICAR) module, the implications of aerosol-induced snow darkening on the regional hydroclimate of the Himalayas are investigated in this study. The aerosols deposited on snow shows a distinct regional heterogeneity. The albedo reduction due to aerosols shows a west to east gradient during pre-monsoon season and this results in the positive radiative effect of about 29 Wm<sup>-2</sup>, 17 Wm<sup>-2</sup> and 5 Wm<sup>-2</sup> over western, central and eastern Himalayas respectively. The reduction in the snow albedo also results in the sign reversal of the aerosol direct radiative effect i.e., from warming to cooling at the top of the atmosphere during pre-monsoon season. The excess solar energy trapped at the surface due to snow darkening warms the surface (0.66-1.9 K) and thus decreases the snow cover extent significantly. This results in the reduction of the number of snow-covered days by more than a month over the western Himalayas and about 10 – 15 days over the central Himalayas. The early snowmelt due to aerosol-induced snow darkening results in the increase of runoff throughout the melting season. Therefore, the present study highlights the heterogeneous response of aerosol induced snow albedo feedbacks over the Himalayan region and its impact on the snowpack and hydrology, which has further implications on the freshwater availability over the region.</p>

scholarly journals Simulation of the isotopic composition of stratospheric water vapour – Part 1: Description and evaluation of the EMAC model

2015 ◽  
Vol 15 (10) ◽  
pp. 5537-5555 ◽  
Author(s):  
R. Eichinger ◽  
P. Jöckel ◽  
S. Brinkop ◽  
M. Werner ◽  
S. Lossow
Keyword(s):  
Isotopic Composition ◽  
Water Vapour ◽  
General Circulation ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Isotope Ratios ◽  
Physical Fractionation ◽  
Water Isotopologues ◽  
Stratospheric Water Vapour

Abstract. This modelling study aims at an improved understanding of the processes that determine the water vapour budget in the stratosphere by means of the investigation of water isotope ratios. An additional (and separate from the actual) hydrological cycle has been introduced into the chemistry–climate model EMAC, including the water isotopologues HDO and H218O and their physical fractionation processes. Additionally an explicit computation of the contribution of methane oxidation to H2O and HDO has been incorporated. The model expansions allow detailed analyses of water vapour and its isotope ratio with respect to deuterium throughout the stratosphere and in the transition region to the troposphere. In order to assure the correct representation of the water isotopologues in the model's hydrological cycle, the expanded system has been evaluated in several steps. The physical fractionation effects have been evaluated by comparison of the simulated isotopic composition of precipitation with measurements from a ground-based network (GNIP) and with the results from the isotopologue-enabled general circulation model ECHAM5-wiso. The model's representation of the chemical HDO precursor CH3D in the stratosphere has been confirmed by a comparison with chemical transport models (1-D, CHEM2D) and measurements from radiosonde flights. Finally, the simulated stratospheric HDO and the isotopic composition of water vapour have been evaluated, with respect to retrievals from three different satellite instruments (MIPAS, ACE-FTS, SMR). Discrepancies in stratospheric water vapour isotope ratios between two of the three satellite retrievals can now partly be explained.

scholarly journals IMPACTS OF LAND COVER AND GREENHOUSE GAS (GHG) CONCENTRATION CHANGES ON THE HYDROLOGICAL CYCLE IN AMAZON BASIN: A REGIONAL CLIMATE MODEL STUDY

2015 ◽  
Vol 15 ◽  
Author(s):  
Vinícius Machado Rocha ◽  
Francis Wagner Silva Correia ◽  
Prakki Satyamurty ◽  
Saulo Ribeiro De Freitas ◽  
Demerval Soares Moreira ◽  
...  
Keyword(s):  
Land Cover ◽  
Regional Climate Model ◽  
Greenhouse Gas ◽  
Amazon Basin ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Regional Climate ◽  
Model Study ◽  
Concentration Changes

scholarly journals Human-caused Indo-Pacific warm pool expansion

2016 ◽  
Vol 2 (7) ◽  
pp. e1501719 ◽  
Author(s):  
Evan Weller ◽  
Seung-Ki Min ◽  
Wenju Cai ◽  
Francis W. Zwiers ◽  
Yeon-Hee Kim ◽  
...  
Keyword(s):  
Climate Model ◽  
Hydrological Cycle ◽  
Heat Content ◽  
Warm Pool ◽  
Small Island ◽  
Past Century ◽  
The Pacific ◽  
Pacific Warm Pool ◽  
Basin Scale ◽  
Climate Model Simulations

The Indo-Pacific warm pool (IPWP) has warmed and grown substantially during the past century. The IPWP is Earth’s largest region of warm sea surface temperatures (SSTs), has the highest rainfall, and is fundamental to global atmospheric circulation and hydrological cycle. The region has also experienced the world’s highest rates of sea-level rise in recent decades, indicating large increases in ocean heat content and leading to substantial impacts on small island states in the region. Previous studies have considered mechanisms for the basin-scale ocean warming, but not the causes of the observed IPWP expansion, where expansion in the Indian Ocean has far exceeded that in the Pacific Ocean. We identify human and natural contributions to the observed IPWP changes since the 1950s by comparing observations with climate model simulations using an optimal fingerprinting technique. Greenhouse gas forcing is found to be the dominant cause of the observed increases in IPWP intensity and size, whereas natural fluctuations associated with the Pacific Decadal Oscillation have played a smaller yet significant role. Further, we show that the shape and impact of human-induced IPWP growth could be asymmetric between the Indian and Pacific basins, the causes of which remain uncertain. Human-induced changes in the IPWP have important implications for understanding and projecting related changes in monsoonal rainfall, and frequency or intensity of tropical storms, which have profound socioeconomic consequences.

scholarly journals Aerosol–Ice Formation Closure: A Southern Great Plains Field Campaign

2021 ◽  
pp. 1-50
Author(s):  
D. A. Knopf ◽  
K. R. Barry ◽  
T. A. Brubaker ◽  
L. G. Jahl ◽  
K. A., L. Jankowski ◽  
...  
Keyword(s):  
Pilot Study ◽  
Great Plains ◽  
Climate Models ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Ice Formation ◽  
Crystal Formation ◽  
Atmospheric Sciences ◽  
Immersion Freezing ◽  
Mixed Phase Clouds

AbstractPrediction of ice formation in clouds presents one of the grand challenges in the atmospheric sciences. Immersion freezing initiated by ice-nucleating particles (INPs) is the dominant pathway of primary ice crystal formation in mixed-phase clouds, where supercooled water droplets and ice crystals coexist, with important implications for the hydrological cycle and climate. However, derivation of INP number concentrations from an ambient aerosol population in cloud-resolving and climate models remains highly uncertain. We conducted an aerosol-ice formation closure pilot study using a field-observational approach to evaluate the predictive capability of immersion freezing INPs. The closure study relies on co-located measurements of the ambient size-resolved and single-particle composition and INP number concentrations. The acquired particle data serve as input in several immersion freezing parameterizations, that are employed in cloud-resolving and climate models, for prediction of INP number concentrations. We discuss in detail one closure case study in which a front passed through the measurement site, resulting in a change of ambient particle and INP populations. We achieved closure in some circumstances within uncertainties, but we emphasize the need for freezing parameterization of potentially missing INP types and evaluation of the choice of parameterization to be employed. Overall, this closure pilot study aims to assess the level of parameter details and measurement strategies needed to achieve aerosol-ice formation closure. The closure approach is designed to accurately guide immersion freezing schemes in models, and ultimately identify the leading causes for climate model bias in INP predictions.

scholarly journals A Two-Dimensional Coupled Atmosphere-Ice-Sheet-Continent Model Designed for Paleoclimatic Simulations

1990 ◽  
Vol 14 ◽  
pp. 55-57 ◽  
Author(s):  
M.B. Esch ◽  
K. Herterich
Keyword(s):  
Climate Model ◽  
Hydrological Cycle ◽  
Vertical Plane ◽  
Ice Sheet ◽  
Ice Age ◽  
Balance Model ◽  
Two Dimensional ◽  
Geothermal Heat ◽  
The North ◽  
Slow Evolution

We present a two-dimensional climate model to be used for basic dynamic studies on ice-age time scales (103 to 106 years). The model contains an ice sheet, where flow and temperature are calculated in a vertical plane, oriented in the north-south direction. The model ice sheet is forced by a zonally-averaged atmospheric energy-balance model, including a seasonal cycle and a simplified hydrological cycle, which specifies ice temperature and the mass balance at the ice-sheet surface. At the bottom of the ice sheet, the geothermal heat flux is prescribed. In addition, delayed bedrock sinking (or bedrock rising) is assumed.A stationary state is achieved after 200 000 model years. This long time scale is introduced by the slow evolution of the temperature field within the ice sheet. Using reasonable parameter values and presently observed precipitation patterns, modified by ice-sheet orography, the observed thickness to length ratio (4 km/3300 km) of the Laurentide ice sheet can be simulated within a realistic build-up time (40 000 years). Near the ice bottom, temperate regions developed. They may have had an important effect on ice-sheet build-up and ice-sheet decay.

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