scholarly journals Storylines of the 2018 Northern Hemisphere heat wave at pre-industrial and higher global warming levels

2020 ◽  
Author(s):  
Kathrin Wehrli ◽  
Mathias Hauser ◽  
Sonia I. Seneviratne
Keyword(s):  
Global Warming ◽  
Northern Hemisphere ◽  
Large Scale ◽  
Heat Waves ◽  
Circulation Pattern ◽  
Community Earth System Model ◽  
Anomalous Atmospheric Circulation ◽  
Simultaneous Heat ◽  
Different Levels

<p>The 2018 summer was unusually hot in large areas of the Northern Hemisphere and simultaneous heat waves on three continents led to major impacts to agriculture and society. The event was driven by the anomalous atmospheric circulation pattern during that summer and it was only possible in a climate with global warming. There are indications that in a future, warmer climate similar events might occur regularly, affecting major ‘breadbasket’ regions of the Northern Hemisphere.</p><p>This study aims to understand the role of climate change for driving the intensity of the 2018 summer and to explore the sensitivity to changing warming levels. Model simulations are performed using the Community Earth System Model to investigate storylines for the extreme 2018 summer given the observed atmospheric large-scale circulation but different levels of background global warming: no human imprint, the 2018 conditions, and different mean global warming levels (1.5°C, 2°C, 3°C, and 4°C). The storylines explore the consequences of the event in an alternative warmer or colder world and thus help to increase our understanding of the drivers involved. The results reveal a strong contribution by the present-day level of global warming and provide an outlook to similar events in a possible future climate.</p>

Six-fold increase in historical Northern Hemisphere concurrent large heatwaves driven by warming and changing atmospheric circulations

2021 ◽  
pp. 1-39
Author(s):  
Cassandra D.W. Rogers ◽  
Kai Kornhuber ◽  
Sarah E. Perkins-Kirkpatrick ◽  
Paul C. Loikith ◽  
Deepti Singh
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Warm Season ◽  
Fold Increase ◽  
Circulation Pattern ◽  
Positive Influence ◽  
Climate Risks ◽  
Circulation Patterns ◽  
Multiple Regions ◽  
Barents And Kara Seas

AbstractSimultaneous heatwaves affecting multiple regions (referred to as concurrent heatwaves), pose compounding threats to various natural and societal systems, including global food chains, emergency response systems, and reinsurance industries. While anthropogenic climate change is increasing heatwave risks across most regions, the interactions between warming and circulation changes that yield concurrent heatwaves remain understudied. Here, we quantify historical (1979-2019) trends in concurrent heatwaves during the warm-season (May-September, MJJAS) across the Northern Hemisphere mid- to high-latitudes. We find a significant increase of ~46% in the mean spatial extent of concurrent heatwaves, ~17% increase in their maximum intensity, and ~6-fold increase in their frequency. Using Self-Organising Maps, we identify large-scale circulation patterns (300 hPa) associated with specific concurrent heatwave configurations across Northern Hemisphere regions. We show that observed changes in the frequency of specific circulation patterns preferentially increase the risk of concurrent heatwaves across particular regions. Patterns linking concurrent heatwaves across eastern North America, eastern and northern Europe, parts of Asia, and the Barents and Kara Seas, show the largest increases in frequency (~5.9 additional days per decade). We also quantify the relative contributions of circulation pattern changes and warming to overall observed concurrent heatwave day frequency trends. While warming has a predominant and positive influence on increasing concurrent heatwaves, circulation pattern changes have a varying influence and account for up to 0.8 additional concurrent heatwave days per decade. Identifying regions with an elevated risk of concurrent heatwaves and understanding their drivers is indispensable for evaluating projected climate risks on interconnected societal systems and fostering regional preparedness in a changing climate.

Self-Concept Predicts Academic Achievement across Levels of the Achievement Distribution: Domain-Specificity for Math and Reading

2018 ◽  
Author(s):  
Maria Ines Susperreguy ◽  
Pamela Davis-Kean ◽  
Kathryn Duckworth ◽  
Meichu Chen
Keyword(s):  
Large Scale ◽  
Demographic Variables ◽  
Self Concept ◽  
Data Sets ◽  
Regression Analyses ◽  
Achievement Data ◽  
Different Populations ◽  
Robust Evidence ◽  
Different Levels

This study examines whether self-concept of ability in math and reading predicts later math and reading attainment across different levels of achievement. Data from three large-scale longitudinal data sets, the ALSPAC, NICHD-SECCYD, and PSID-CDS, were used to answer this question by employing quantile regression analyses. After controlling for demographic variables, child characteristics, and early ability, the findings indicate that self-concept of ability in math and reading predicts later achievement in each respective domain across all quantile levels of achievement. These results were replicated across the three data sets representing different populations and provide robust evidence for the role of self-concept of ability in understanding achievement from early childhood to adolescence across the spectrum of performance (low to high).

scholarly journals The influence of vegetation on the ITCZ and South Asian monsoon in HadCM3

2012 ◽  
Vol 3 (1) ◽  
pp. 87-96 ◽  
Author(s):  
M. P. McCarthy ◽  
J. Sanjay ◽  
B. B. B. Booth ◽  
K. Krishna Kumar ◽  
R. A. Betts
Keyword(s):  
Land Cover ◽  
Northern Hemisphere ◽  
South Asian ◽  
Vegetation Cover ◽  
Large Scale ◽  
Asian Monsoon ◽  
South Asian Monsoon ◽  
Tropical Circulation ◽  
Global Vegetation

Abstract. The role of global vegetation on the large-scale tropical circulation is examined in the version 3 Hadley Centre climate model (HadCM3). Alternative representations of global vegetation cover from observations and a dynamic global vegetation model (DGVM) were used as the land-cover component for a number of HadCM3 experiments under a nominal present day climate state, and compared to the simulations using the standard land cover map of HadCM3. The alternative vegetation covers result in a large scale cooling of the Northern Hemisphere extra-tropics relative to the HadCM3 standard, resulting in a southward shift in the location of the inter-tropical convergence zone (ITCZ). A significant reduction in Indian monsoon precipitation is also found, which is related to a weakening of the South Asian monsoon circulation, broadly consistent with documented mechanisms relating to temperature and snow perturbations in the Northern Hemisphere extra-tropics in winter and spring, delaying the onset of the monsoon. The role of the Northern Hemisphere extra-tropics on tropical climate is demonstrated, with an additional representation of vegetation cover based on DGVM simulated changes in Northern Hemisphere vegetation from the end of the 21st Century. This experiment shows that through similar processes the simulated extra-tropical vegetation changes in the future contribute to a strengthening of the South Asian monsoon in this model. These findings provide renewed motivation to give careful consideration to the role of global scale vegetation feedbacks when looking at climate change, and its impact on the tropical circulation and South Asian monsoon in the latest generation of Earth System models.

scholarly journals Storylines of the 2018 Northern Hemisphere heat wave at pre-industrial and higher global warming levels

2020 ◽  
Author(s):  
Kathrin Wehrli ◽  
Mathias Hauser ◽  
Sonia I. Seneviratne
Keyword(s):  
Global Warming ◽  
Atmospheric Circulation ◽  
Northern Hemisphere ◽  
System Model ◽  
Boreal Summer ◽  
Extreme Temperatures ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Anomalous Atmospheric Circulation ◽  
Maximum Temperatures

Abstract. Extreme temperatures were experienced over a large part of the Northern Hemisphere during the 2018 boreal summer (hereafter referred to as NH2018 event), leading to major impacts to agriculture and society in the affected countries. Previous studies highlighted both the anomalous atmospheric circulation patterns during the event and the background warming due to human greenhouse gas emissions as main drivers for the event. In this study, we present Earth System Model experiments investigating different storylines of the NH2018 event given the same atmospheric circulation and alternative background global warming for: no human imprint, the 2018 conditions, and different mean global warming levels (1.5 °C, 2 °C, 3 °C, and 4 °C). The results reveal that the human-induced background warming was a strong contributor to the intensity of the NH2018 event, and that resulting extremes under similar atmospheric circulation conditions at higher levels of global warming would reach very dangerous levels. About 32 % (61 %) of the inhabited or agricultural area in the investigated region would reach maximum temperatures over 40 °C under 2 °C (4 °C) of global warming and similar atmospheric circulation conditions.

scholarly journals Spatial and temporal identification of baric systems in low troposphere and midtroposphere

2017 ◽  
pp. 41-47
Author(s):  
E. V. Samchuk
Keyword(s):  
Northern Hemisphere ◽  
Large Scale ◽  
Nearest Neighbor ◽  
Ground Level ◽  
Automatic Identification ◽  
Output Data ◽  
Software Application ◽  
Entire Depth ◽  
System Movement ◽  
Different Levels

According to the terms of synoptic meteorology baric systems of low troposphere and midtroposphere are the main objects for research of large-scale circulation processes. Therefore, knowledge of their typical places of origin, their movement and characteristics is extremely critical. The purpose of this publication consists in analyzing existing methods and algorithms used for identification and tracking of baric systems in low troposphere and midtroposphere. This will allow for distinguishing the most output data and methods for further usage. Results. A unified methodology for identification and tracking of baric systems was developed. It is based on a step-by-step identification of isolated clusters of low and high pressure or geopotential height throughout the entire depth of low and middle troposphere from a ground level to a 500 hPa isobaric level. Centers of clusters on different levels over a specific period of time are integrated in a single vertical profile which represents a certain baric system. Tracking of baric system movement is conducted using the method of the nearest neighbor which was improved to ensure more accurate detection of fast-moving and short-living cyclones. A software application for automatic identification of baric systems in the Northern Hemisphere and generation of sets of kinematic maps of natural synoptic periods was developed. A database of baric systems which existed in the Northern hemisphere during 1976-2016 was also created.

Coherent changes in large-scale thermal structure and baroclinic life cycle of synoptic eddies in the Northern Hemisphere under global warming

2020 ◽  
Author(s):  
Pei-Chun Hsu ◽  
Huang-Hsiung Hsu
Keyword(s):  
Global Warming ◽  
Life Cycle ◽  
Temperature Gradient ◽  
Northern Hemisphere ◽  
Large Scale ◽  
Thermal Structure ◽  
Mean Flow ◽  
Upper Troposphere ◽  
The Past ◽  
Synoptic Eddies

<p><strong>There is a growing concern that human-induced climate change has been affecting weather systems. However, robust observational evidences that confirm the links between global warming and synoptic phenomena at the global scale are lacking. Here we reveal robust covarying signals between poleward temperature gradient and baroclinic life cycle of synoptic (1-10 days) eddies under global warming. We note that the changes in temperature structure in Northern Hemisphere winter and summer in the past decades are different. In boreal winter, the tropospheric warming has been larger in tropical upper troposphere and around 30°N than for the midlatitude (30-60°N). This inhomogeneous warming resulted in the enhancement of poleward temperature gradient in the subtropical upper troposphere and in the lower midlatitude (30-45°N). We observed correlated increasing trends in the entire baroclinic life cycle of synoptic eddies</strong><strong> — </strong><strong>including eddy fluxes of heat and momentum, and zonal mean jet</strong><strong> — </strong><strong>associated with steepened poleward temperature gradients in these regions in the winter Northern Hemisphere over the past four decades. By contrast, in the summer Northern Hemisphere, the overall tropospheric warming over the mid- to high-latitude land areas has been accompanied by weakly reduced synoptic eddy activities and zonal mean flow. Our findings suggest that if greenhouse gas–induced warming continue to change the atmospheric thermal structure as projected in a warming climate, extratropical synoptic disturbances and large-scale circulations may change accordingly. </strong></p>

scholarly journals Storylines of the 2018 Northern Hemisphere heatwave at pre-industrial and higher global warming levels

2020 ◽  
Vol 11 (4) ◽  
pp. 855-873
Author(s):  
Kathrin Wehrli ◽  
Mathias Hauser ◽  
Sonia I. Seneviratne
Keyword(s):  
Global Warming ◽  
Atmospheric Circulation ◽  
Northern Hemisphere ◽  
System Model ◽  
Boreal Summer ◽  
Daily Maximum ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Anomalous Atmospheric Circulation ◽  
Maximum Temperatures

Abstract. Extreme temperatures were experienced over a large part of the Northern Hemisphere during the 2018 boreal summer (hereafter referred to as “NH2018 event”), leading to major impacts on agriculture and society in the affected countries. Previous studies highlighted both the anomalous atmospheric circulation patterns during the event and the background warming due to human greenhouse gas emissions as main drivers of the event. In this study, we present Earth system model experiments investigating different storylines of the NH2018 event given the same atmospheric circulation and alternative background global warming for no human imprint, the 2018 conditions, and different mean global warming levels 1.5, 2, 3 and 4 ∘C. The results reveal that the human-induced background warming was a strong contributor to the intensity of the NH2018 event, and that resulting extremes under similar atmospheric circulation conditions at higher levels of global warming would reach dangerous levels. Compared to 9 % during the NH2018 event, about 13 % (34 %) of the inhabited or agricultural area in the investigated region would reach daily maximum temperatures over 40 ∘C under 2 ∘C (4 ∘C) of global warming and similar atmospheric circulation conditions.

scholarly journals Potential Vorticity Constraint on the Flow between Two Basins

2007 ◽  
Vol 37 (9) ◽  
pp. 2251-2266 ◽  
Author(s):  
Jiayan Yang ◽  
James F. Price
Keyword(s):  
Potential Vorticity ◽  
Large Scale ◽  
Circulation Pattern ◽  
Viscous Drag ◽  
Frictional Torque ◽  
Boundary Current ◽  
Coriolis Parameter ◽  
Basin Scale ◽  
Straightforward Consequence

Abstract This paper examines the role of potential vorticity (PV) balance in source- and sink-driven flows between two basins. As shown in previous studies, PV advection into a basin, say a positive PV advection, requires a negative frictional torque to maintain a steady PV balance. This sense of torque may be provided by a cyclonic boundary current within the basin. The PV advection through a channel is due almost entirely to advection of planetary PV, f/H, where f is the Coriolis parameter and H is the column thickness. Therefore a localized change of depth, and thus H in the channel, directly affects the PV transport and will result in a basinwide change of the circulation pattern. For example, if the channel depth is made shallower while holding the transport fixed, the PV advection is then increased and the result may be a strong recirculation within the basin, as much as two orders of magnitude greater than the transport through the channel. When the basins are connected by two channels at different latitudes or with different sill depths, the throughflow is found to be divided between the two channels in a way that satisfies the integral constraint for flow around an island. The partition of the flow between two channels appears to be such as to minimize the net frictional torque. In still another set of experiments, the large-scale pressure difference (layer thickness) between the basins is specified and held fixed, while the throughflow is allowed to vary in response to changes in the frictional torque. The interbasin transport is strongly influenced by the length of the boundary or the magnitude of the viscosity in the sense that a greater PV frictional torque allows a greater PV transport and vice versa. This result is counterintuitive, if it is assumed that the throughflow is determined by viscous drag within the channel but is a straightforward consequence of the basin-scale PV balance. Thus, the important frictional effect in these experiments is on the basin-scale flow and not on the channel scale.

scholarly journals Evolving the neuroendocrine physiology of human and primate cooperation and collective action

2015 ◽  
Vol 370 (1683) ◽  
pp. 20150014 ◽  
Author(s):  
Benjamin C. Trumble ◽  
Adrian V. Jaeggi ◽  
Michael Gurven
Keyword(s):  
Collective Action ◽  
Large Scale ◽  
Future Research ◽  
Territorial Defence ◽  
Multiple Components ◽  
Current State ◽  
Wide Range ◽  
Range Of Variation ◽  
Different Levels

While many hormones play vital roles in facilitating or reinforcing cooperative behaviour, the neurohormones underlying competitive and cooperative behaviours are largely conserved across all mammals. This raises the question of how endocrine mechanisms have been shaped by selection to produce different levels of cooperation in different species. Multiple components of endocrine physiology—from baseline hormone concentrations, to binding proteins, to the receptor sensitivity and specificity—can evolve independently and be impacted by current socio-ecological conditions or individual status, thus potentially generating a wide range of variation within and between species. Here, we highlight several neurohormones and variation in hormone receptor genes associated with cooperation, focusing on the role of oxytocin and testosterone in contexts ranging from parenting and pair-bonding to reciprocity and territorial defence. While the studies reviewed herein describe the current state of the literature with regard to hormonal modulators of cooperation and collective action, there is still a paucity of research on hormonal mechanisms that help facilitate large-scale collective action. We end by discussing several potential areas for future research.

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