scholarly journals Changes in Frequency of Large Precipitation Accumulations over Land in a Warming Climate from the CESM Large Ensemble: The Roles of Moisture, Circulation, and Duration

2019 ◽  
Vol 32 (17) ◽  
pp. 5397-5416 ◽  
Author(s):  
Jesse Norris ◽  
Gang Chen ◽  
J. David Neelin
Keyword(s):  
First Century ◽  
Minor Effect ◽  
Large Ensemble ◽  
Almost Everywhere ◽  
Community Earth System Model ◽  
Twenty First Century ◽  
Projected Changes ◽  
The Tropics ◽  
The Given ◽  
Local Average

ABSTRACT Projected changes in the frequency of major precipitation accumulations (hundreds of millimeters), integrated over rainfall events, over land in the late twenty-first century are analyzed in the Community Earth System Model (CESM) Large Ensemble, based on the RCP8.5 scenario. Accumulation sizes are sorted by the local average recurrence interval (ARI), ranging from 0.1 to 100 years, for the current and projected late-twenty-first-century climates separately. For all ARIs, the frequency of exceedance of the given accumulation size increases in the future climate almost everywhere, especially for the largest accumulations, with the 100-yr accumulation becoming about 3 times more frequent, averaged over the global land area. The moisture budget allows the impacts of individual factors—moisture, circulation, and event duration—to be isolated. In the tropics, both moisture and circulation cause large future increases, enhancing the 100-yr accumulation by 23% and 13% (average over tropical land), and are individually responsible for making the current-climate 100-yr accumulation 2.7 times and 1.8 times more frequent, but effects of shorter durations slightly offset these effects. In the midlatitudes, large accumulations become about 5% longer in duration, but are predominantly controlled by enhanced moisture, with the 100-yr accumulation (land average) becoming 2.4 times more frequent, and 2.2 times more frequent due to moisture increases alone. In some monsoon-affected regions, the 100-yr accumulation becomes more than 5 times as frequent, where circulation changes are the most impactful factor. These projections indicate that changing duration of events is a relatively minor effect on changing accumulations, their future enhancement being dominated by enhanced intensity (the combination of moisture and circulation).

scholarly journals Projected Changes in Climate Extremes Using CMIP6 Simulations Over SREX Regions

2021 ◽  
Vol 5 (3) ◽  
pp. 481-497
Author(s):  
Mansour Almazroui ◽  
Fahad Saeed ◽  
Sajjad Saeed ◽  
Muhammad Ismail ◽  
Muhammad Azhar Ehsan ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Extreme Events ◽  
First Century ◽  
Maximum Temperature ◽  
Annual Maximum ◽  
Temperature And Precipitation ◽  
Projected Change ◽  
Twenty First Century ◽  
Projected Changes ◽  
The Tropics

AbstractThis paper presents projected changes in extreme temperature and precipitation events by using Coupled Model Intercomparison Project phase 6 (CMIP6) data for mid-century (2036–2065) and end-century (2070–2099) periods with respect to the reference period (1985–2014). Four indices namely, Annual maximum of maximum temperature (TXx), Extreme heat wave days frequency (HWFI), Annual maximum consecutive 5-day precipitation (RX5day), and Consecutive Dry Days (CDD) were investigated under four socioeconomic scenarios (SSP1-2.6; SSP2-4.5; SSP3-7.0; SSP5-8.5) over the entire globe and its 26 Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) regions. The projections show an increase in intensity and frequency of hot temperature and precipitation extremes over land. The intensity of the hottest days (as measured by TXx) is projected to increase more in extratropical regions than in the tropics, while the frequency of extremely hot days (as measured by HWFI) is projected to increase more in the tropics. Drought frequency (as measured by CDD) is projected to increase more over Brazil, the Mediterranean, South Africa, and Australia. Meanwhile, the Asian monsoon regions (i.e., South Asia, East Asia, and Southeast Asia) become more prone to extreme flash flooding events later in the twenty-first century as shown by the higher RX5day index projections. The projected changes in extremes reveal large spatial variability within each SREX region. The spatial variability of the studied extreme events increases with increasing greenhouse gas concentration (GHG) and is higher at the end of the twenty-first century. The projected change in the extremes and the pattern of their spatial variability is minimum under the low-emission scenario SSP1-2.6. Our results indicate that an increased concentration of GHG leads to substantial increases in the extremes and their intensities. Hence, limiting CO2 emissions could substantially limit the risks associated with increases in extreme events in the twenty-first century.

scholarly journals Late Twenty-First-Century Changes in the Midlatitude Atmospheric Circulation in the CESM Large Ensemble

2017 ◽  
Vol 30 (15) ◽  
pp. 5943-5960 ◽  
Author(s):  
Y. Peings ◽  
J. Cattiaux ◽  
S. Vavrus ◽  
Gudrun Magnusdottir
Keyword(s):  
Atmospheric Circulation ◽  
Extreme Temperature ◽  
Internal Variability ◽  
First Century ◽  
The Arctic ◽  
Arctic Amplification ◽  
Large Ensemble ◽  
Longitudinal Sector ◽  
Twenty First Century ◽  
Projected Changes

Projected changes in the midlatitude atmospheric circulation at the end of the twenty-first century are investigated using coupled ocean–atmosphere simulations from the Community Earth System Model Large Ensemble (CESM-LENS). Different metrics are used to describe the response of the midlatitude atmospheric dynamics in 40 ensemble members covering the 1920–2100 period. Contrasted responses are identified depending on the season and longitudinal sector that are considered. In winter, a slowdown of the zonal flow and an increase in waviness is found over North America, while the European sector exhibits a reinforced westerly flow and decreased waviness. Extreme temperature events in midlatitudes are more sensitive to thermodynamical than dynamical changes, and a general decrease in the intensity of wintertime cold spells is found. Analyses of individual ensemble members reveal a large spread in circulation changes due to internal variability. Causes for this spread are found to be tied to the Arctic amplification in the Pacific–North American sector and to the polar stratosphere in the North Atlantic. A competition mechanism is also discussed between the midlatitude response to polar versus tropical changes. While the upper-tropospheric tropical warming pushes the jet stream poleward, in winter, Arctic amplification and the weaker polar vortex exert an opposite effect. This competition results in a narrowing of the jet path in the midlatitudes, leading to decreased/unchanged waviness/blockings. This interpretation somewhat reconciles conflicting results between the hypothesized effect of Arctic amplification and projected changes in midlatitude flow characteristics. This study also illustrates that further understanding of regional processes is critical for anticipating changes in the midlatitude dynamics.

scholarly journals El Niño–Induced Tropical Droughts in Climate Change Projections

2009 ◽  
Vol 22 (23) ◽  
pp. 6456-6476 ◽  
Author(s):  
Caio A. S. Coelho ◽  
Lisa Goddard
Keyword(s):  
Climate Change ◽  
Twentieth Century ◽  
El Niño ◽  
El Nino ◽  
First Century ◽  
Spatial Extent ◽  
Drought Risk ◽  
Twenty First Century ◽  
Projected Changes ◽  
The Tropics

Abstract El Niño brings widespread drought (i.e., precipitation deficit) to the tropics. Stronger or more frequent El Niño events in the future and/or their intersection with local changes in the mean climate toward a future with reduced precipitation would exacerbate drought risk in highly vulnerable tropical areas. Projected changes in El Niño characteristics and associated teleconnections are investigated between the twentieth and twenty-first centuries. For climate change models that reproduce realistic oceanic variability of the El Niño–Southern Oscillation (ENSO) phenomenon, results suggest no robust changes in the strength or frequency of El Niño events. These models exhibit realistic patterns, magnitude, and spatial extent of El Niño–induced drought patterns in the twentieth century, and the teleconnections are not projected to change in the twenty-first century, although a possible slight reduction in the spatial extent of droughts is indicated over the tropics as a whole. All model groups investigated show similar changes in mean precipitation for the end of the twenty-first century, with increased precipitation projected between 10°S and 10°N, independent of the ability of the models to replicate ENSO variability. These results suggest separability between climate change and ENSO-like climate variability in the tropics. As El Niño–induced precipitation drought patterns are not projected to change, the observed twentieth-century variability is used in combination with model-projected changes in mean precipitation for assessing year-to-year drought risk in the twenty-first century. Results suggest more locally consistent changes in regional drought risk among models with good fidelity in reproducing ENSO variability.

scholarly journals Ice-supersaturation and the potential for contrail formation in a changing climate

2015 ◽  
Vol 6 (1) ◽  
pp. 317-349 ◽  
Author(s):  
E. A. Irvine ◽  
K. P. Shine
Keyword(s):  
Northern Hemisphere ◽  
Air Traffic ◽  
First Century ◽  
Cmip5 Models ◽  
Polar Regions ◽  
Upper Troposphere ◽  
Twenty First Century ◽  
Using Data ◽  
Projected Changes ◽  
The Tropics

Abstract. Ice-supersaturation (ISS) in the upper-troposphere and lower stratosphere is important for the formation of cirrus cloud and long-lived contrails. We analyse projected changes to 250 hPa ISS distribution and frequency over the twenty-first century using data from the RCP8.5 simulations of a selection of CMIP5 models. The models show a global-mean annual-mean decrease in ISS frequency of 4% by the end of the twenty-first century, relative to the present-day period 1979–2005. Changes are analysed in further detail for three sub-regions where air traffic is already high and increasing (Northern Hemisphere mid-latitudes) or expected to increase (tropics and Northern Hemisphere polar regions). The largest change is seen in the tropics, where a reduction of around 9% in ISS frequency by the end of the century is driven by the strong warming of the upper troposphere. In the Northern Hemisphere mid-latitudes the multi-model mean change is an increase in ISS frequency of 1%; however the sign of the change is not only model-dependent but also has a strong latitudinal and seasonal dependence. In the Northern Hemisphere polar regions there is an increase in ISS frequency of 5% in the annual-mean. These results suggest that over the 21st century climate change may have large impacts on the potential for contrail formation; actual changes to contrail cover will also depend on changes to the volume of air traffic, aircraft technology and flight routing.

scholarly journals Atmospheric Carbon Dioxide Variability in the Community Earth System Model: Evaluation and Transient Dynamics during the Twentieth and Twenty-First Centuries

2013 ◽  
Vol 26 (13) ◽  
pp. 4447-4475 ◽  
Author(s):  
Gretchen Keppel-Aleks ◽  
James T. Randerson ◽  
Keith Lindsay ◽  
Britton B. Stephens ◽  
J. Keith Moore ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Fossil Fuel ◽  
First Century ◽  
Atmospheric Co2 ◽  
System Model ◽  
Historical Period ◽  
Community Earth System Model ◽  
The Mean ◽  
Twenty First Century ◽  
Fossil Fuel Emissions

Abstract Changes in atmospheric CO2 variability during the twenty-first century may provide insight about ecosystem responses to climate change and have implications for the design of carbon monitoring programs. This paper describes changes in the three-dimensional structure of atmospheric CO2 for several representative concentration pathways (RCPs 4.5 and 8.5) using the Community Earth System Model–Biogeochemistry (CESM1-BGC). CO2 simulated for the historical period was first compared to surface, aircraft, and column observations. In a second step, the evolution of spatial and temporal gradients during the twenty-first century was examined. The mean annual cycle in atmospheric CO2 was underestimated for the historical period throughout the Northern Hemisphere, suggesting that the growing season net flux in the Community Land Model (the land component of CESM) was too weak. Consistent with weak summer drawdown in Northern Hemisphere high latitudes, simulated CO2 showed correspondingly weak north–south and vertical gradients during the summer. In the simulations of the twenty-first century, CESM predicted increases in the mean annual cycle of atmospheric CO2 and larger horizontal gradients. Not only did the mean north–south gradient increase due to fossil fuel emissions, but east–west contrasts in CO2 also strengthened because of changing patterns in fossil fuel emissions and terrestrial carbon exchange. In the RCP8.5 simulation, where CO2 increased to 1150 ppm by 2100, the CESM predicted increases in interannual variability in the Northern Hemisphere midlatitudes of up to 60% relative to present variability for time series filtered with a 2–10-yr bandpass. Such an increase in variability may impact detection of changing surface fluxes from atmospheric observations.

scholarly journals Introduction: Postcolonial Reading Publics

2017 ◽  
Vol 4 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Ankhi Mukherjee
Keyword(s):  
First Century ◽  
The Other ◽  
Special Issue ◽  
British India ◽  
Authorial Intention ◽  
Writing Theory ◽  
History Of ◽  
Twenty First Century ◽  
The Given ◽  
Discursive Context

AbstractIn this introduction to the special issue, “Postcolonial Reading Publics,” Mukherjee charts the history of reception of two texts, one a Bengali novel published in British India, the other a Shakespeare adaptation staged in twenty-first-century Kolkata, to examine the fortuitous ways in which reading publics baffle or exceed authorial intention and the given text’s addressable objects. Offering summaries of and continuities among the four essays that constitute the volume, the introduction ends with an analysis of the salience of this discursive context for postcolonial writing, theory, and critique in a world literary frame.

scholarly journals Greenland Surface Mass Balance as Simulated by the Community Earth System Model. Part II: Twenty-First-Century Changes

2014 ◽  
Vol 27 (1) ◽  
pp. 215-226 ◽  
Author(s):  
Miren Vizcaíno ◽  
William H. Lipscomb ◽  
William J. Sacks ◽  
Michiel van den Broeke
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Earth System Model ◽  
First Century ◽  
System Model ◽  
Surface Mass Balance ◽  
Earth System ◽  
Surface Mass ◽  
Community Earth System Model ◽  
Twenty First Century

Abstract This study presents the first twenty-first-century projections of surface mass balance (SMB) changes for the Greenland Ice Sheet (GIS) with the Community Earth System Model (CESM), which includes a new ice sheet component. For glaciated surfaces, CESM includes a sophisticated calculation of energy fluxes, surface albedo, and snowpack hydrology (melt, percolation, refreezing, etc.). To efficiently resolve the high SMB gradients at the ice sheet margins and provide surface forcing at the scale needed by ice sheet models, the SMB is calculated at multiple elevations and interpolated to a finer 5-km ice sheet grid. During a twenty-first-century simulation driven by representative concentration pathway 8.5 (RCP8.5) forcing, the SMB decreases from 372 ± 100 Gt yr−1 in 1980–99 to −78 ± 143 Gt yr−1 in 2080–99. The 2080–99 near-surface temperatures over the GIS increase by 4.7 K (annual mean) with respect to 1980–99, only 1.3 times the global increase (+3.7 K). Snowfall increases by 18%, while surface melt doubles. The ablation area increases from 9% of the GIS in 1980–99 to 28% in 2080–99. Over the ablation areas, summer downward longwave radiation and turbulent fluxes increase, while incoming shortwave radiation decreases owing to increased cloud cover. The reduction in GIS-averaged July albedo from 0.78 in 1980–99 to 0.75 in 2080–99 increases the absorbed solar radiation in this month by 12%. Summer warming is strongest in the north and east of Greenland owing to reduced sea ice cover. In the ablation area, summer temperature increases are smaller due to frequent periods of surface melt.

scholarly journals Twenty-First Century Projected Changes in Extreme Temperature over Côte d’Ivoire (West Africa)

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Assi L. M. Yapo ◽  
Adama Diawara ◽  
Fidèle Yoroba ◽  
Benjamin K. Kouassi ◽  
Mouhamadou B. Sylla ◽  
...  
Keyword(s):  
Cote D'ivoire ◽  
Côte D’Ivoire ◽  
Extreme Temperature ◽  
First Century ◽  
Cote D’Ivoire ◽  
Côte D'ivoire ◽  
Frequency Index ◽  
The Future ◽  
Twenty First Century ◽  
Projected Changes

The projection of the future climate changes is of paramount importance inasmuch as it contributes to provide useful information for adaptation planning worldwide to local scales. This study investigated the future changes using four temperature related indices based on an ensemble of 14 CORDEX-Africa simulations at 0.44° × 0.44° of resolution under the RCP4.5 and RCP8.5 scenarios. These indices indicate moderate extremes over Côte d’Ivoire. The results show an increase in the warm extreme indices such as the warm spell days index (HWFI), very warm days frequency index (TX90P), and the warm nights frequency index (TN90P) over the entire country under both emission scenarios. The increase in these indices was higher under RCP8.5 and reached 85, 72, and 90% for HWFI, TX90P, and TN90P respectively. In addition, the magnitude of the changes is relevant along the coastal areas in the 2031–2060 and 2071–2100 periods. Moreover, the intra period extreme temperature range (ETR) shows future decrease following a south-north gradient with values in the range [−0.5; 1.5°C] over the country during January–March (JFM) and October–December (OND) seasons whereas an increase (~0.5°C) is projected for April–June (AMJ) and July–September (JAS) seasons, particularly in the central and northern parts. The minimum temperature increases faster than the maximum, except in AMJ and JAS in the central and northern regions. On the other hand, the changes in the indices based on the mean values of the reference period (1976–2005) are in concordance to the expected warming at the end of the twenty-first century with important trends. The projected changes are, however, subject to uncertainties, which are higher under RCP8.5 than under RCP4.5 scenarios. Overall, these changes are meaningful as all the 14 CORDEX-Africa simulations agree to an increase of warm extreme temperature.

Romantic Portraits and Contemporary Audiences: Report from an Exhibition on the History of Emotions

2018 ◽  
Vol 7 (2) ◽  
pp. 145-166
Author(s):  
Anna Schram Vejlby
Keyword(s):  
First Century ◽  
Emotional Communication ◽  
History Of Emotions ◽  
The People ◽  
History Of ◽  
Complex Emotion ◽  
Twenty First Century ◽  
Historical Methods ◽  
The Given ◽  
Emotional Landscape

This article combines two issues: the actual emotional landscape of Danish portraiture from the first half of the nineteenth century and twenty-first-century audiences' response to these portraits. My research is based on written sources, art historical methods of the interpretation of visual material, and surveys among the audiences of the Hirschsprung Collection in Copenhagen, where the exhibition Keeping up Appearances. Portraits and emotions in the Golden Age takes place in the autumn of 2017. The exhibition is based on previous research that I have conducted into emotion in Danish portraiture and will be an occasion to reevaluate earlier surveys in order to present new conclusions in this article. The article explores the psychological and emotional circumstances that surround examples of some of the finest Danish portraits of the 1800s and how the modern individual can attain a more profound understanding of these images and the range of emotions they embody. The portraits' historical public had no doubts as to the deep and complex emotion embedded in them, but today they often prove more difficult to interpret since a prior understanding of the given period is required in order to fully grasp the people depicted and the different things they may have felt. When audiences see a portrait in the twenty-first century they are often compelled to interpret it in the same way that they would interpret living people. This creates a set of challenges in our relation to and understanding of a person in a portrait through a given time and space. I will use Lisa Feldman Barrett's research on emotional communication in my analyses of the encounter between the portrait and the modern viewer.

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