Speleothem record from Pentadactylos cave (Cyprus): high-resolution insight into climatic variations during MIS 6 and MIS 5

2020 ◽  
Author(s):  
Carole Nehme ◽  
Sophie Verheyden ◽  
Tobias Kluge ◽  
Therese Weissbach ◽  
Fadi Nader ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fluid Inclusions ◽  
Climate Models ◽  
Temperature Shift ◽  
Clumped Isotopes ◽  
East Mediterranean ◽  
Climate Conditions ◽  
Climatic Variations ◽  
Stable Conditions ◽  
Mis 5E

<p>An improved understanding of medium and short-term changes in temperature and rainfall in the East Mediterranean is necessary for a comprehensive description of the regional climate regime. In particular, it can help advancing current climate models and predictions. A new paleoclimate record from Cyprus gives new insights into climatic variations during MIS 6 and 5 for this region. A 66 cm long speleothem from Pentadactylos cave in the Kyrenia range (800 m asl) was extensively dated with the U/Th method and investigated for petrography, fluid inclusions, stable and clumped isotopes. The stalagmite grew from 174.6 ± 0.7 to 112.2 ± 0.5 ka BP. The growth rate varies from 31 to 5 mm/ka during the early-MIS6 and evolving from 123 to 18 mm/ka at the end-MIS6. The onset of MIS5e is marked by a high growth rate (125 mm/ka) until growth decreased drastically after 122 ka. Growth rate and stalagmite diameter as well as δ<sup>18</sup>O and δ<sup>13</sup>C curves are positively correlated. We interpret the δ<sup>18</sup>Oc signal as being controlled by effective infiltration and thus rainfall amount. Climate conditions during early-MIS6 were highly variable (δ<sup>18</sup>O<sub>c</sub>) on a millennial-scale with several short-lived wet episodes during sapropel 6. From 141 to 132 ka, δ<sup>18</sup>O<sub>c</sub> suggests general dry/cold conditions with low bio-pedological activity, followed by a growth stop during H11. The δ<sup>18</sup>O values during the Eemian wet period in Cyprus are driven by the source effect (sapropel 5). Stable conditions during MIS 5e were rather short: ~2 ka, as shown in the δ<sup>13</sup>C signal. After 122 ka, a slow deterioration of the soil cover coupled with low rainfall amounts during the glacial inception period show rather a regional decoupling phase. Fluid inclusions show a clear shift (4-5‰) in δ<sup>18</sup>O<sub>w</sub> between end-MIS 6 and MIS 5e. Clumped isotopes measurements indicate kinetic effects between calcite and water of up to ~1‰. After correction for kinetics using Δ<sub>47</sub>, an estimate for the MIS6-5 temperature shift in the East-Mediterranean is >10°C.</p>

scholarly journals Paleoclimate in continental northwestern Europe during the Eemian and early Weichselian (125–97 ka): insights from a Belgian speleothem

2016 ◽  
Vol 12 (7) ◽  
pp. 1445-1458 ◽  
Author(s):  
Stef Vansteenberge ◽  
Sophie Verheyden ◽  
Hai Cheng ◽  
R. Lawrence Edwards ◽  
Eddy Keppens ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Regional Climate ◽  
Time Interval ◽  
Last Interglacial ◽  
High Resolution Data ◽  
Climate Conditions ◽  
Spatial Coverage ◽  
Stable Conditions ◽  
Mis 5E ◽  
Δ13c And Δ18o

Abstract. The last interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of last interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alps, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European last interglacial continental records is essential, and speleothems, because of their ability to obtain excellent chronologies, can provide a major contribution. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse Cave in Belgium. Han-9 formed between 125.3 and  ∼  97 ka, with interruptions of growth occurring at 117.3–112.9 and 106.6–103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) composition. The speleothem started growing relatively late within the last interglacial, at 125.3 ka, as other European continental archives suggest that Eemian optimum conditions were already present during that time. It appears that the initiation of Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka; however, at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the Marine Isotope Stage (MIS) 5e–5d transition. At 117.5 ka, drastic vegetation changes are recorded by Han-9 δ13C immediately followed by a cessation of speleothem growth at 117.3 ka, suggesting a transition to significantly dryer conditions. The Han-9 record covering the early Weichselian displays larger amplitudes in both isotope proxies and changes in stalagmite morphology, evidencing increased variability compared to the Eemian. Stadials that appear to be analogous to those in Greenland are recognized in Han-9, and the chronology is consistent with other European (speleothem) records. Greenland Stadial 25 is reflected as a cold/dry period within Han-9 stable isotope proxies, and the second interruption in speleothem growth occurs simultaneously with Greenland Stadial 24.

scholarly journals Paleoclimate in continental northwestern Europe during the Eemian and Early-Weichselian (125–97 ka): insights from a Belgian speleothem

2016 ◽  
Author(s):  
Stef Vansteenberge ◽  
Sophie Verheyden ◽  
Hai Cheng ◽  
Lawrence R. Edwards ◽  
Eddy Keppens ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Regional Climate ◽  
Time Interval ◽  
Last Interglacial ◽  
High Resolution Data ◽  
Climate Conditions ◽  
Spatial Coverage ◽  
Stable Conditions ◽  
Mis 5E ◽  
Δ13c And Δ18o

Abstract. The Last Interglacial serves as an excellent time interval for studying climate dynamics during past warm periods. Speleothems have been successfully used for reconstructing the paleoclimate of Last Interglacial continental Europe. However, all previously investigated speleothems are restricted to southern Europe or the Alpine region, leaving large parts of northwestern Europe undocumented. To better understand regional climate changes over the past, a larger spatial coverage of European Last Interglacial speleothems is essential. Here, we present new, high-resolution data from a stalagmite (Han-9) obtained from the Han-sur-Lesse cave in Belgium. The Han-9 formed between 125.3 and ~97 ka, with interruptions of growth occurring at 117.3–112.9 ka and 106.6–103.6 ka. The speleothem was investigated for its growth, morphology and stable isotope (δ13C and δ18O) content. Speleothem formation within the Last Interglacial started relatively late in Belgium, as this is the oldest sample of that time period found so far, dated at 125.3 ka. Other European continental archives suggest that Eemian optimum conditions were already present during that time, therefore it appears that the initiation of the Han-9 growth is caused by an increase in moisture availability, linked to wetter conditions around 125.3 ka. The δ13C and δ18O proxies indicate a period of relatively stable conditions after 125.3 ka, however at 120 ka the speleothem δ18O registered the first signs of regionally changing climate conditions, being a modification of ocean source δ18O linked to an increase in ice volume towards the MIS 5e-5d transition. The end of the Eemian is marked by drastic vegetation changes recorded in the speleothem δ13C at 117.5 ka, immediately followed by a stop in speleothem growth at 117.3 ka, suggesting that climate became significantly dryer. The Han-9 record covering the Early-Weichselian displays larger amplitudes in both the isotope proxies and the stalagmite morphology, evidencing increased variability compared to the Eemian. Greenland Stadials are recognized in the Han-9 and the chronology is consistent with other European (speleothem) records. Greenland Stadial 25 is reflected as a cold/dry period within the stable isotope proxies and the second interruption in speleothem growth occurs simultaneously with Greenland Stadial 24.

scholarly journals Transferability Intercomparison: An Opportunity for New Insight on the Global Water Cycle and Energy Budget

2007 ◽  
Vol 88 (3) ◽  
pp. 375-384 ◽  
Author(s):  
E. S. Takle ◽  
J. Roads ◽  
B. Rockel ◽  
W. J. Gutowski ◽  
R. W. Arritt ◽  
...  
Keyword(s):  
Energy Budget ◽  
Climate Models ◽  
Climate Model ◽  
Water Cycle ◽  
Regional Climate ◽  
Climate Conditions ◽  
Continental Scale ◽  
Global Water Cycle ◽  
Wide Range ◽  
Global Water

A new approach, called transferability intercomparisons, is described for advancing both understanding and modeling of the global water cycle and energy budget. Under this approach, individual regional climate models perform simulations with all modeling parameters and parameterizations held constant over a specific period on several prescribed domains representing different climatic regions. The transferability framework goes beyond previous regional climate model intercomparisons to provide a global method for testing and improving model parameterizations by constraining the simulations within analyzed boundaries for several domains. Transferability intercomparisons expose the limits of our current regional modeling capacity by examining model accuracy on a wide range of climate conditions and realizations. Intercomparison of these individual model experiments provides a means for evaluating strengths and weaknesses of models outside their “home domains” (domain of development and testing). Reference sites that are conducting coordinated measurements under the continental-scale experiments under the Global Energy and Water Cycle Experiment (GEWEX) Hydrometeorology Panel provide data for evaluation of model abilities to simulate specific features of the water and energy cycles. A systematic intercomparison across models and domains more clearly exposes collective biases in the modeling process. By isolating particular regions and processes, regional model transferability intercomparisons can more effectively explore the spatial and temporal heterogeneity of predictability. A general improvement of model ability to simulate diverse climates will provide more confidence that models used for future climate scenarios might be able to simulate conditions on a particular domain that are beyond the range of previously observed climates.

scholarly journals Qualitative Analysis of the Effect of Weeds Removal in Paddy Ecosystems in Fallow Season

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Leru Zhou ◽  
Zhigang Liu ◽  
Tiejun Zhou
Keyword(s):  
Growth Rate ◽  
Equilibrium State ◽  
Excretion Rate ◽  
Critical Value ◽  
Inorganic Fertilizer ◽  
Paddy Fields ◽  
Asymptotically Stable ◽  
Intrinsic Growth Rate ◽  
Stable Conditions ◽  
Coexistence Equilibrium

In the paper, we introduce a differential equations model of paddy ecosystems in the fallow season to study the effect of weeds removal from the paddy fields. We found that there is an unstable equilibrium of the extinction of weeds and herbivores in the system. When the intensity of weeds removal meets certain conditions and the intrinsic growth rate of herbivores is higher than their excretion rate, there is a coexistence equilibrium state in the system. By linearizing the system and using the Routh–Hurwitz criterion, we obtained the local asymptotically stable conditions of the coexistence equilibrium state. The critical value formula of the Hopf bifurcation is presented too. The model demonstrates that weeds removal from paddy fields could largely reduce the weeds biomass in the equilibrium state, but it also decreases the herbivore biomass, which probably reduces the content of inorganic fertilizer in the soil. We found a particular intensity of weeds removal that could result in the minimum content of inorganic fertilizer, suggesting weeds removal should be kept away from this intensity.

scholarly journals The Future of Midlatitude Cyclones

2019 ◽  
Vol 5 (4) ◽  
pp. 407-420 ◽  
Author(s):  
Jennifer L. Catto ◽  
Duncan Ackerley ◽  
James F. Booth ◽  
Adrian J. Champion ◽  
Brian A. Colle ◽  
...  
Keyword(s):  
Vertical Structure ◽  
Climate Models ◽  
Future Research ◽  
Extratropical Cyclones ◽  
Latent Heating ◽  
Climate Conditions ◽  
Structure Characteristics ◽  
Regional Impacts ◽  
Climate Simulations ◽  
The Future

Abstract Purpose of Review This review brings together recent research on the structure, characteristics, dynamics, and impacts of extratropical cyclones in the future. It draws on research using idealized models and complex climate simulations, to evaluate what is known and unknown about these future changes. Recent Findings There are interacting processes that contribute to the uncertainties in future extratropical cyclone changes, e.g., changes in the horizontal and vertical structure of the atmosphere and increasing moisture content due to rising temperatures. Summary While precipitation intensity will most likely increase, along with associated increased latent heating, it is unclear to what extent and for which particular climate conditions this will feedback to increase the intensity of the cyclones. Future research could focus on bridging the gap between idealized models and complex climate models, as well as better understanding of the regional impacts of future changes in extratropical cyclones.

scholarly journals Significance of Fracture-Filling Rose-Like Calcite Crystal Clusters in the SE Pyrenees

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 522
Author(s):  
David Cruset ◽  
Jordi Ibáñez-Insa ◽  
Irene Cantarero ◽  
Cédric M. John ◽  
Anna Travé
Keyword(s):  
Fluid Inclusions ◽  
Aromatic Hydrocarbons ◽  
Major Elements ◽  
Clumped Isotopes ◽  
X Ray Diffraction ◽  
Calcite Crystal ◽  
Fresh Groundwater ◽  
Raman Analysis ◽  
X Ray ◽  
Co2 Release

Fracture-filling rose-like clusters of bladed calcite crystals are found in the northern sector of the Cadí thrust sheet (SE Pyrenees). This unusual calcite crystal morphology has been characterized by using optical and electron microscope, X-ray diffraction, Raman spectroscopy, δ18O, δ13C, 87Sr/86Sr, clumped isotopes, and major and rare earth elements + yttrium (REEs + Y) analysis. Petrographic observations and powder X-ray diffraction measurements indicate that these bladed crystals are mainly made of massive rhombic crystals with the conventional (104) faces, as well as of possibly younger, less abundant, and smaller laminar crystals displaying (108) and/or ( 1 ¯ 08) rhombic faces. Raman analysis of liquid fluid inclusions indicates the presence of aromatic hydrocarbons and occasionally alkanes. Clumped isotopes thermometry reflects that bladed calcite precipitated from meteoric fluids at ~60–65 °C. The 87Sr/86Sr ratios and major elements and REEs content of calcite indicate that these fluids interacted with Eocene marine carbonates. The presence of younger ‘nailhead’ calcite indicates later migration of shallow fresh groundwater. The results reveal that rose-like calcite clusters precipitated, at least in the studied area, due to a CO2 release by boiling of meteoric waters that mixed with benzene and aromatic hydrocarbons. This mixing decreased the boiling temperature at ~60–65 °C. The results also suggest that the high Sr content in calcite, and probably the presence of proteins within hydrocarbons trapped in fluid inclusions, controlled the precipitation of bladed crystals with (104) rhombohedral faces.

scholarly journals Evaluation of a New Statistical Method—TIN-Copula–for the Bias Correction of Climate Models’ Extreme Parameters

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 243 ◽  
Author(s):  
Georgia Lazoglou ◽  
Christina Angnostopoulou ◽  
Konstantia Tolika ◽  
Gräler Benedikt
Keyword(s):  
Statistical Method ◽  
Bias Correction ◽  
Climate Models ◽  
Regional Climate ◽  
Extreme Temperature ◽  
Regional Climate Models ◽  
Climate Conditions ◽  
Copula Theory ◽  
Mean Temperature ◽  
Copula Method

During the last decades, global and regional climate models have been widely used for the estimation of future climate conditions. Unfortunately, the models’ estimated values present important biases relative to the observed values, especially when the estimations refer to extremes. Consequently, several researchers have studied several statistical methods that are able to minimize the biases between climate models and observed values. The present study evaluates a new statistical method for bias correction: The triangular irregular network (TIN)-copula method. This method is a combination of the triangular irregular networks and the copula theory. In the present research, the new method is applied to ten Mediterranean stations and its results are compared with the bias-corrected values of three other widely used methods: The delta, the scaling, and the empirical quantile mapping methods. The analysis was made for maximum mean temperature (TMX) and minimum mean temperature (TMN) as well as for extreme precipitation (R99). According to the results, the TIN-copula method is able to correct extreme temperature and precipitation values, estimated by regional climate models, with high accuracy. Additionally, it is proven that the TIN-copula method is a useful tool for bias correction as it presents several advantages compared with the other methods, and it is recommended for future works.

Front related model evaluation of multi-year simulations from hydrostatic to convection-permitting scales in the greater Alpine region

2020 ◽  
Author(s):  
Heimo Truhetz ◽  
Dom Heinzeller ◽  
Robert Ritter ◽  
Laurin Herbsthofer
Keyword(s):  
Climate Models ◽  
Evaluation Studies ◽  
Weather Prediction ◽  
Detection Algorithm ◽  
Alpine Region ◽  
Model Intercomparison ◽  
Grid Spacing ◽  
Climate Conditions ◽  
Mountainous Regions ◽  
Front Detection

<p>Atmospheric fronts play a major role in day-to-day life and are well known for sharp changes in local weather conditions. In mountainous regions, the interaction between fronts and the orography supports the development of characteristic precipitation patterns and may even cause specific weather phenomena, like thunderstorms, föhn events, and others. It is therefore an interesting question, how such fronts evolve in the next few days or how they will behave under changing climate conditions.</p><p>However, due to the complexity of fronts and limitations in numerical weather prediction or climate models, state-of-the-art automated front detection algorithms are largely restricted to the model they are applied onto. In particular, the outcome of these algorithms depends the discretization scheme of the underlying model (e.g. the grid spacing) and hence they may fail in model intercomparison or evaluation studies when data is given in various different grids.</p><p>In the present work, a diagnostic front detection algorithm, that is designed to overcome such model dependencies, is introduced and its applicability for model intercomparison is demonstrated by means of simple analytic test functions and idealized simulations of a baroclinic wave (i.e. the Jablonowksi and Williamson test) conducted with MPAS (60 km and 15 km grid spacing). Finally, the algorithm is exemplarily applied onto latest WRF evaluation simulations (15 km and 3 km grid spacing) from the CORDEX-FPS Convection initiative and the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF) (~25 km grid spacing) to investigate differences in front statistics in the greater Alpine region of the period 2006 to 2009.</p><p>The study is funded by the Austrian Klima- und Energiefonds through the Austrian Climate Research Programme (ACRP) by means of the project "Research for Climate Protection: Value-adding Convection-Permitting Climate Simulations Austria" (reclip:convex, project id: B769999).</p>

Assessment of future climate change impacts on the hydrological regime of selected Greek areas with different climate conditions

2016 ◽  
Vol 48 (5) ◽  
pp. 1327-1342 ◽  
Author(s):  
Spyridon Paparrizos ◽  
Andreas Matzarakis
Keyword(s):  
Climate Change ◽  
Climate Models ◽  
Hydrological Cycle ◽  
Meteorological Data ◽  
Hydrological Regime ◽  
Future Climate ◽  
Future Climate Change ◽  
Water Losses ◽  
Climate Conditions ◽  
The Future

Assessment of future variations of streamflow is essential for research regarding climate and climate change. This study is focused on three agricultural areas widespread in Greece and aims to assess the future response of annual and seasonal streamflow and its impacts on the hydrological regime, in combination with other fundamental aspects of the hydrological cycle in areas with different climate classification. ArcSWAT ArcGIS extension was used to simulate the future responses of streamflow. Future meteorological data were obtained from various regional climate models, and analysed for the periods 2021–2050 and 2071–2100. In all the examined areas, streamflow is expected to be reduced. Areas characterized by continental climate will face minor reductions by the mid-century that will become very intense by the end and thus these areas will become more resistant to future changes. Autumn season will face the strongest reductions. Areas characterized by Mediterranean conditions will be very vulnerable in terms of future climate change and winter runoff will face the most significant decreases. Reduced precipitation is the main reason for decreased streamflow. High values of actual evapotranspiration by the end of the century will act as an inhibitor towards reduced runoff and partly counterbalance the water losses.

scholarly journals The Influence of Atmospheric Blocking on Extreme Winter Minimum Temperatures in North America

2016 ◽  
Vol 29 (12) ◽  
pp. 4361-4381 ◽  
Author(s):  
Kirien Whan ◽  
Francis Zwiers ◽  
Jana Sillmann
Keyword(s):  
United States ◽  
North America ◽  
Extreme Events ◽  
Climate Models ◽  
Primary Source ◽  
The United States ◽  
Climate Projections ◽  
Cold Temperatures ◽  
Climate Conditions ◽  
The Difference

Abstract Regional climate models (RCMs) are the primary source of high-resolution climate projections, and it is of crucial importance to evaluate their ability to simulate extreme events under current climate conditions. Many extreme events are influenced by circulation features that occur outside, or on the edges of, RCM domains. Thus, it is of interest to know whether such dynamically controlled aspects of extremes are well represented by RCMs. This study assesses the relationship between upstream blocking and cold temperature extremes over North America in observations, reanalysis products (ERA-Interim and NARR), and RCMs (CanRCM4, CRCM5, HIRHAM5, and RCA4). Generalized extreme value distributions were fitted to winter minimum temperature (TNn) incorporating blocking frequency (BF) as a covariate, which is shown to have a significant influence on TNn. The magnitude of blocking influence in the RCMs is consistent with observations, but the spatial extent varies. CRCM5 and HIRHAM5 reproduce the pattern of influence best compared to observations. CanRCM4 and RCA4 capture the influence of blocking in British Columbia and the northeastern United States, but the extension of influence that is seen in observations and reanalysis into the southern United States is not evident. The difference in the 20-yr return value (20RV) of TNn between high and low BF in the Pacific Ocean indicates that blocking is associated with a decrease of up to 15°C in the 20RV over the majority of the United States and in western Canada. In northern North America the difference in the 20RV is positive as blocking is associated with warmer extreme cold temperatures. The 20RVs are generally simulated well by the RCMs.

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