scholarly journals A Last Glacial Maximum forcing dataset for ocean modelling

2019 ◽  
Author(s):  
Anne L. Morée ◽  
Jörg Schwinger
Keyword(s):  
Last Glacial Maximum ◽  
Computational Cost ◽  
Coupled Model ◽  
Glacial Maximum ◽  
Sea Surface Salinity ◽  
Specific Humidity ◽  
Data Set ◽  
Last Glacial ◽  
Ocean Models ◽  
Fully Coupled

Abstract. Model simulations of the Last Glacial Maximum (LGM, ~ 21 000 years before present) can aid the interpretation of proxy records, help to gain an improved mechanistic understanding of the LGM climate system and are valuable for the evaluation of model performance in a different climate state. Ocean-ice only model configurations forced by prescribed atmospheric data (referred to as “forced ocean models”) drastically reduce the computational cost of paleoclimate modelling as compared to fully coupled model frameworks. While feedbacks between the atmosphere and ocean-sea-ice compartments of the Earth system are not present in such model configurations, many scientific questions can be addressed with models of this type. The data presented here are derived from fully coupled paleoclimate simulations of the Palaeoclimate Modelling Intercomparison Project (PMIP3). The data are publicly accessible at the NIRD Research Data Archive at https://doi.org/10.11582/2019.00011 (Morée and Schwinger, 2019). They consist of 2-D anomaly forcing fields suitable for use in ocean models that employ a bulk forcing approach. The data include specific humidity, downwelling longwave and shortwave radiation, precipitation, wind (v and u components), temperature and sea surface salinity (SSS). All fields are provided as climatological mean anomalies between LGM and pre-industrial times. These anomaly data can therefore be added to any pre-industrial ocean forcing data set in order to obtain forcing fields representative of LGM conditions as simulated by PMIP3 models. These forcing data provide a means to simulate the LGM in a computationally efficient way, while still taking advantage of the complexity of fully coupled model set-ups. Furthermore, the dataset can be easily updated to reflect results from upcoming and future paleo model intercomparison activities.

scholarly journals A Last Glacial Maximum forcing dataset for ocean modelling

2020 ◽  
Vol 12 (4) ◽  
pp. 2971-2985
Author(s):  
Anne L. Morée ◽  
Jörg Schwinger
Keyword(s):  
Last Glacial Maximum ◽  
Coupled Model ◽  
Research Data ◽  
Glacial Maximum ◽  
Specific Humidity ◽  
Wave Radiation ◽  
Last Glacial ◽  
Model Set ◽  
Ocean Models ◽  
Fully Coupled

Abstract. Model simulations of the Last Glacial Maximum (LGM; ∼ 21 000 years before present) can aid the interpretation of proxy records, can help to gain an improved mechanistic understanding of the LGM climate system, and are valuable for the evaluation of model performance in a different climate state. Ocean-ice only model configurations forced by prescribed atmospheric data (referred to as “forced ocean models”) drastically reduce the computational cost of palaeoclimate modelling compared to fully coupled model frameworks. While feedbacks between the atmosphere and ocean and sea-ice compartments of the Earth system are not present in such model configurations, many scientific questions can be addressed with models of this type. Our dataset supports simulations of the LGM in a forced ocean model set-up while still taking advantage of the complexity of fully coupled model set-ups. The data presented here are derived from fully coupled palaeoclimate simulations of the Palaeoclimate Modelling Intercomparison Project phase 3 (PMIP3). The data are publicly accessible at the National Infrastructure for Research Data (NIRD) Research Data Archive at https://doi.org/10.11582/2020.00052 (Morée and Schwinger, 2020). They consist of 2-D anomaly forcing fields suitable for use in ocean models that employ a bulk forcing approach and are optimized for use with CORE forcing fields. The data include specific humidity, downwelling long-wave and short-wave radiation, precipitation, wind (v and u components), temperature, and sea surface salinity (SSS). All fields are provided as climatological mean anomalies between LGM and pre-industrial (PI) simulations. These anomaly data can therefore be added to any pre-industrial ocean forcing dataset in order to obtain forcing fields representative of LGM conditions as simulated by PMIP3 models. Furthermore, the dataset can be easily updated to reflect results from upcoming and future palaeo-model intercomparison activities.

A continental perspective on the timing of the last glacial maximum in Australia - utilising methods for integrating multiple time-uncertain, variable resolution proxy records.

2020 ◽  
Author(s):  
Haidee Cadd ◽  
Lynda Petherick ◽  
Jonathan Tyler ◽  
Annika Herbert ◽  
Timothy Cohen ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Change Point ◽  
Regional Scale ◽  
Glacial Maximum ◽  
Change Point Analysis ◽  
Multiple Time ◽  
Low Resolution ◽  
Data Set ◽  
Last Glacial ◽  
Proxy Records

<p>Many palaeoclimate and palaeoenvironmental records have low sampling resolution, few age constraints, and are based on climate proxies that may reflect an uncertain mixture of local and regional influences. Objective spatial and temporal comparisons of multiple palaeo records and identification of regional scale trends can therefore be difficult.. Low resolution palaeo records are often excluded from regional syntheses due to low dating or sample density, however such records can contribute meaningful information to regional syntheses if their inherent uncertainties are considered. Explicitly incorporating the age uncertainties allows for a more robust interpretation of synchronous periods of change.</p><p>Here we discuss the use of a method for determining the timing of palaeoclimate events using multiple time-uncertain palaeo records. This method allows for the incorporation of a variety of records, regardless of proxy type or sampling resolution. We demonstrate the power of this method using a case study from the SHeMax project (Southern Hemisphere Last Glacial Maximum project), aiming to understanding the nature and timing of the LGM in Australia. Further expansion of our analyses will allow the incorporation of both continuous and discontinuous climate archives, interrogation of spatial and temporal synchronicity and coherency of climate changes across broad regions.</p><p>An extended LGM period, characterised by multiple distinct stages that varied regionally and in its timing and evolution, has been suggested to have occurred in Australia; however this hypothesis has yet to be tested objectively. Comparisons during this time period have been hampered by the limited number, low resolution, and age-uncertainty of terrestrial archives. In order to gain a greater understanding of the spatial and temporal patterns of climate change during MIS2, we have compiled all available proxy records of climate and envrionmental variability from across Australia for the period 35 – 15 ka (n=40). Analysing age-uncertainty in time series requires an approach that treats all data consistently. For each record, a revised age-depth model was developed using the SH13 calibration curve and Bayesian age-depth modelling techniques. Complex records (e.g. pollen records) were reduced to Principal Curves, in order to provide a one-dimensional summary of patterns of change in each data-set. Monte-Carlo change point analysis was then used to identify the timing of major changes within each record, along with the uncertainty around each change point. We assess the spatial heterogeneity of the timing of the major climatic changes during the 35 – 15 ka period and determine the probability of common timing of change across Australia. We find the onset of an extended period of relative aridity in Australia occurred synchronously (within uncertainty) at ca. 28 ka. Dry and cool conditions persisted at most sites until ca. 15 – 18 ka, with the onset of more humid conditions occurring along a latitudinal gradient. The occurrence of a millennial scale episode of increased moisture balance between ca. 25 – 21 ka is evident only in the most highly resolved records.</p>

scholarly journals Last Glacial Maximum world ocean simulations at eddy-permitting and coarse resolutions: do eddies contribute to a better consistency between models and palaeoproxies?

2013 ◽  
Vol 9 (6) ◽  
pp. 2669-2686 ◽  
Author(s):  
M. Ballarotta ◽  
L. Brodeau ◽  
J. Brandefelt ◽  
P. Lundberg ◽  
K. Döös
Keyword(s):  
High Resolution ◽  
Sea Ice ◽  
Last Glacial Maximum ◽  
World Ocean ◽  
Glacial Maximum ◽  
Ocean Dynamics ◽  
Global Ocean ◽  
Western Boundary ◽  
Data Set ◽  
Last Glacial

Abstract. Most state-of-the-art climate models include a coarsely resolved oceanic component, which hardly captures detailed dynamics, whereas eddy-permitting and eddy-resolving simulations are developed to reproduce the observed ocean. In this study, an eddy-permitting and a coarse resolution numerical experiment are conducted to simulate the global ocean state for the period of the Last Glacial Maximum (LGM, ~26 500 to 19 000 yr ago) and to investigate the improvements due to taking into account the smaller spatial scales. The ocean state from each simulation is confronted with a data set from the Multiproxy Approach for the Reconstruction of the Glacial Ocean (MARGO) sea surface temperatures (SSTs), some reconstructions of the palaeo-circulations and a number of sea-ice reconstructions. The western boundary currents and the Southern Ocean dynamics are better resolved in the high-resolution experiment than in the coarse simulation, but, although these more detailed SST structures yield a locally improved consistency between model predictions and proxies, they do not contribute significantly to the global statistical score. The SSTs in the tropical coastal upwelling zones are also not significantly improved by the eddy-permitting regime. The models perform in the mid-latitudes but as in the majority of the Paleoclimate Modelling Intercomparison Project simulations, the modelled sea-ice conditions are inconsistent with the palaeo-reconstructions. The effects of observation locations on the comparison between observed and simulated SST suggest that more sediment cores may be required to draw reliable conclusions about the improvements introduced by the high resolution model for reproducing the global SSTs. One has to be careful with the interpretation of the deep ocean state which has not reached statistical equilibrium in our simulations. However, the results indicate that the meridional overturning circulations are different between the two regimes, suggesting that the model parametrizations might also play a key role for simulating past climate states.

scholarly journals Glacial–interglacial changes in H<sub>2</sub><sup>18</sup>O, HDO and deuterium excess – results from the fully coupled ECHAM5/MPI-OM Earth system model

2016 ◽  
Vol 9 (2) ◽  
pp. 647-670 ◽  
Author(s):  
M. Werner ◽  
B. Haese ◽  
X. Xu ◽  
X. Zhang ◽  
M. Butzin ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Last Glacial Maximum ◽  
Ice Cores ◽  
Glacial Maximum ◽  
The Arctic ◽  
Spatial Gradient ◽  
Deuterium Excess ◽  
Last Glacial ◽  
Simulation Results ◽  
Fully Coupled

Abstract. In this study we present the first results of a new isotope-enabled general circulation model set-up. The model consists of the fully coupled ECHAM5/MPI-OM atmosphere–ocean model, enhanced by the JSBACH interactive land surface scheme and an explicit hydrological discharge scheme to close the global water budget. Stable water isotopes H218O and HDO have been incorporated into all relevant model components. Results of two equilibrium simulations under pre-industrial and Last Glacial Maximum conditions are analysed and compared to observational data and paleoclimate records for evaluating the model's performance in simulating spatial and temporal variations in the isotopic composition of the Earth's water cycle. For the pre-industrial climate, many aspects of the simulation results of meteoric waters are in good to very good agreement with both observations and earlier atmosphere-only simulations. The model is capable of adequately simulating the large spread in the isotopic composition of precipitation between low and high latitudes. A comparison to available ocean data also shows a good model–data agreement; however, a strong bias of overly depleted ocean surface waters is detected for the Arctic region. Simulation results under Last Glacial Maximum boundary conditions also fit to the wealth of available isotope records from polar ice cores, speleothems, as well as marine calcite data. Data–model evaluation of the isotopic composition in precipitation reveals a good match of the model results and indicates that the temporal glacial–interglacial isotope–temperature relation was substantially lower than the present spatial gradient for most mid- to high-latitudinal regions. As compared to older atmosphere-only simulations, a remarkable improvement is achieved for the modelling of the deuterium excess signal in Antarctic ice cores. Our simulation results indicate that cool sub-tropical and mid-latitudinal sea surface temperatures are key for this progress. A recently discussed revised interpretation of the deuterium excess record of Antarctic ice cores in terms of marine relative humidity changes on glacial–interglacial timescales is not supported by our model results.

scholarly journals Global peatlands under future climate – seamless model projections from the Last Glacial Maximum

2021 ◽  
Author(s):  
Jurek Müller ◽  
Fortunat Joos
Keyword(s):  
Last Glacial Maximum ◽  
Climate Model ◽  
Coupled Model ◽  
Glacial Maximum ◽  
Dynamic Global Vegetation Model ◽  
Last Glacial ◽  
The Future ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Peatlands are diverse wetland ecosystems distributed mostly over the northern latitudes and tropics. Globally they store a large portion of the global soil organic carbon and provide important ecosystem services. The future of these systems under continued anthropogenic warming and direct human disturbance has potentially large impacts on atmospheric CO2 and climate. We performed global long term projections of peatland area and carbon over the next 5000 years using a dynamic global vegetation model forced with climate anomalies from ten models of the Coupled Model Intercomparison Project (CMIP6) and three scenarios. These projections are continued from a transient simulation from the Last Glacial Maximum to the present to account for the full transient history. Our results suggest short to long term net losses of global peatland area and carbon, with higher losses under higher emission scenarios. Large parts of today's active northern peatlands are at risk. Conditions for peatlands in the tropics and, in case of mitigation, eastern Asia and western north America improve. Factorial simulations reveal committed historical changes and future rising temperature as the main driver of future peatland loss and increasing precipitations as driver for regional peatland expansion. Additional simulations forced with two CMIP6 scenarios extended transiently beyond 2100, show qualitatively similar results to the standard scenarios, but highlight the importance of extended future scenarios for long term carbon cycle projections. The spread between simulations forced with different climate model anomalies suggests a large uncertainty in projected peatland variables due to uncertain climate forcing. Our study highlights the importance of quantifying the future peatland feedback to the climate system and its inclusion into future earth system model projections.

scholarly journals Widening of the Hadley Cell from Last Glacial Maximum to Future Climate

2017 ◽  
Vol 31 (1) ◽  
pp. 267-281 ◽  
Author(s):  
Seok-Woo Son ◽  
Seo-Yeon Kim ◽  
Seung-Ki Min
Keyword(s):  
Last Glacial Maximum ◽  
Climate Model ◽  
Coupled Model ◽  
Glacial Maximum ◽  
Future Climate ◽  
Hadley Cell ◽  
Zero Crossing ◽  
Model Simulations ◽  
Last Glacial ◽  
Intercomparison Project

Abstract The Hadley cell (HC) change from paleoclimate to future climate is examined by comparing coupled model simulations archived for the Paleoclimate Modeling Intercomparison Project phase 3 (PMIP3) and phase 5 of the Coupled Model Intercomparison Project (CMIP5). Specifically, HC width and strength are evaluated using 100-yr equilibrium simulations for the Last Glacial Maximum (LGM), preindustrial (PI), and extended concentration pathway 4.5 (ECP4.5) conditions. Where available, ECP8.5 simulations are also examined to increase the sample size. All models show a systematic widening of the HC from the LGM to the PI and to the ECP4.5 and ECP8.5 simulations. Such widening, which is found in both hemispheres with more robust change in the Southern Hemisphere (SH) than in the Northern Hemisphere (NH), is significantly correlated with global-mean surface air temperature change and the associated static stability change in the subtropics. Based on the zero-crossing latitude of 500-hPa mass streamfunction, about 4.5° latitude widening of the HC results from global warming of 10°C. HC strength also exhibits a systematic weakening in the NH. However, in the SH, HC strength shows a rather minor change from LGM to ECP4.5 conditions because of the cancellation between HC weakening during the austral summer–fall and its strengthening during the spring. This result, which suggests no systematic relationship between HC width and strength changes, is discussed in the context of quasigeostrophic zonal-mean dynamics. Overall findings are also compared with recent studies that are based on transient climate model simulations.

scholarly journals The PMIP4 contribution to CMIP6 – Part 4: Scientific objectives and experimental design of the PMIP4-CMIP6 Last Glacial Maximum experiments and PMIP4 sensitivity experiments

2017 ◽  
Author(s):  
Masa Kageyama ◽  
Samuel Albani ◽  
Pascale Braconnot ◽  
Sandy P. Harrison ◽  
Peter O. Hopcroft ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Land Surface ◽  
Climate Model ◽  
Model Performance ◽  
Coupled Model ◽  
Glacial Maximum ◽  
Current Phase ◽  
Last Glacial ◽  
Sensitivity Experiments ◽  
Intercomparison Project

Abstract. The Last Glacial Maximum (LGM, 21,000 years ago) is one of the suite of paleoclimate simulations included in the current phase of the Coupled Model Intercomparison Project (CMIP6). It is an interval when insolation was similar to present, but global ice volume was at a maximum, eustatic sea level was at or close to a minimum, greenhouse gas concentrations were lower, atmospheric aerosol loadings were higher than today, and vegetation and land-surface characteristics were different from today. The LGM has been a focus for the Paleoclimate Modelling Intercomparison Project (PMIP) since its inception, and thus many of the problems that might be associated with simulating such a radically different climate are well documented. The LGM state provides an ideal case study for evaluating climate model performance because the changes in forcing and temperature between the LGM and pre-industrial are of the same order of magnitude as those projected for the end of the 21st century. Thus, the CMIP6 LGM experiment could provide additional information that can be used to constrain estimates of climate sensitivity. The design of the Tier 1 LGM experiment (lgm) includes an assessment of uncertainties in boundary conditions, in particular through the use of different reconstructions of the ice sheets and of the change in dust forcing. Additional sensitivity experiments have been designed to quantify feedbacks associated with land-surface changes and aerosol loadings, and to isolate the role of individual forcings. Model analysis and evaluation will capitalise on the relative abundance of palaeoenvironmental observations and quantitative climate reconstructions already available for the LGM.

scholarly journals EVALUATION OF THE DISTRIBUTION MODELS OF "BURITI" AND "PARATUDO", ARBOREAL SPECIES OF THE PANTANAL, WITH DATA OF THE CLIMATE OF THE QUATERNARY AND THE PRESENT

2019 ◽  
Vol 46 (3) ◽  
pp. 101
Author(s):  
Alan Sciamarelli ◽  
Mariele Ramona Torgeski
Keyword(s):  
Last Glacial Maximum ◽  
Potential Distribution ◽  
Glacial Maximum ◽  
Distribution Models ◽  
Data Set ◽  
The Holocene ◽  
Last Glacial ◽  
Climatic Variations ◽  
Environmental Suitability ◽  
Biogeographic History

During the Quaternary, climatic variations caused changes in the size of vegetation formations in the Pantanal, promoting the expansion of seasonal forests at the beginning of the Holocene. Climatic conditions change the patterns of vegetation diversity on continental scales. Mauritia flexuosa L. f., The "Buriti", is a palm tree that explores humid environments with acid soils. While, Tabebuia aurea (Silva Manso) Benth. &Hook.f. ex S.Moore is a species of monodominant occurrence in the Pantanal in extensive areas locally denominated as "paratudal". Data sets of past eras have contributed to the study of plant species biogeography. The models of the potential distribution of these species were generated from the algorithm of the Maxent program with climatic data set of the Last Glacial Maximum (ca 22,000 years AP), Holocene Medium (ca. 6,000 years AP) and present time in two different versions. Potential distribution models with climatic packets from the present in the newer version presented areas of environmental suitability greater than in the older version. In the Holocene Middle and Late Glacial Maximum periods, the areas of environmental suitability were higher than in the newer present version. Many studies on climatic variations on the South American continent confirm the suggestions of the proposed models. The areas of environmental suitability of the species treated in the present are smaller in comparison with Last Glacial Maximum and Average Holocene. The species presented a potential distribution according to the biogeographic history of South America.

scholarly journals Influence of boundary conditions on the Southern Hemisphere atmospheric circulation during the last glacial maximum

2008 ◽  
Vol 23 (4) ◽  
pp. 490-500
Author(s):  
F. Justino ◽  
E. Souza ◽  
M. C. Amorim ◽  
P. L. Silva Dias ◽  
C. F. Lemos
Keyword(s):  
Boundary Conditions ◽  
Southern Hemisphere ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Specific Humidity ◽  
Climate Simulation ◽  
Last Glacial ◽  
Climate Anomalies ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Based upon coupled climate simulations driven by present day and glacial boundary conditions, we demonstrate that although the ice sheet topography modifications during the glacial period are primarily placed in the Northern Hemisphere (NH), a climate simulation that employs the ICE-5G glacial topography delivers significantly enhanced climate anomalies in the Southern Hemisphere (SH) as well. These conditions, in association with climate anomalies produced by the modification of the atmospheric CO² concentration characteristic of the Last Glacial Maximum (LGM) interval, are shown to be the primary forcing of the SH climate during this epoch. Climate anomalies up to -6°C over the Antarctic region and -4°C over South America are predicted to occur in respect to present day conditions. Accompanying the SH cooling in the LGM simulation there exists a remarkable reduction in the specific humidity, which in turn enforces the overall Southern Hemisphere cooling due to the weaker greenhouse capacity of the dry atmosphere.

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