scholarly journals Modelling a tropical-like cyclone in the Mediterranean Sea under present and warmer climate

2021 ◽  
Vol 21 (1) ◽  
pp. 53-71
Author(s):  
Shunya Koseki ◽  
Priscilla A. Mooney ◽  
William Cabos ◽  
Miguel Ángel Gaertner ◽  
Alba de la Vara ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Water Vapour ◽  
Surface Wind ◽  
Sea Surface ◽  
Future Climate Change ◽  
Cumulus Convection ◽  
Present Climate ◽  
Prognostic Variables ◽  
Warm Core

Abstract. This study focuses on a single Mediterranean hurricane (hereafter medicane), to investigate its response to global warming during the middle of the 21st century and assesses the effects of a warmer ocean and a warmer atmosphere on its development. Our investigation uses the state-of-the-art regional climate model WRF to produce the six-member, multi-physics ensembles. Results show that our model setup simulates a realistic cyclone track and the transition from an initial disturbance to a tropical-like cyclone with a deep warm core. However, the simulated transition occurs earlier than for the observed medicane. The response of the medicane to future climate change is investigated with a pseudo global warming (PGW) approach. This is the first application of the PGW framework to medicanes. The PGW approach adds a climate change delta (defined as difference between future and present climate) to WRF's boundary conditions which is obtained for all prognostic variables using the mean change in an ensemble of CMIP5 simulations. A PGW simulation where the climate change delta is added to all prognostic variables (PGWALL) shows that most of the medicane characteristics moderately intensify, e.g. surface wind speed, uptake of water vapour, and precipitation. However, the minimum sea level pressure (SLP) is almost identical to that under present climate conditions. Two additional PGW simulations were undertaken; One simulation adds the projected change in sea surface and skin temperature only (PGWSST) while the second simulation adds the PGW changes to only atmospheric variables (PGWATMS); i.e. we use present-day sea surface temperatures. These simulations show opposing responses of the medicane. In PGWSST, the medicane is more intense than PGWALL as indicated by lower SLP values, the stronger surface wind, and the more intense evaporation and precipitation. In contrast, the medicane in PGWATMS still transitions into a tropical-like cyclone with a deep warm core, but the PGWATMS medicane weakens considerably (SLP, surface wind, and rainfall decrease). This difference can be explained by an increase in water vapour driven by the warmer ocean surface (favourable for cumulus convection). The warmer and drier atmosphere in PGWATMS tends to inhibit condensation (unfavourable for cumulus convection). The warmer ocean and warmer atmosphere have counteracting effects which leads to only a modest enhancement of the medicane by global warming. The novel approach in this study provides new insights into the different roles of warming of the ocean and atmosphere in medicane development.

scholarly journals Modelling a tropical-like cyclone in the Mediterranean Sea under present and warmer climate

2020 ◽  
Author(s):  
Shunya Koseki ◽  
Priscilla A. Mooney ◽  
William Cabos ◽  
Miguel Ángel Gaertner ◽  
Alba de la Vara ◽  
...  
Keyword(s):  
Global Warming ◽  
Regional Climate Model ◽  
Water Vapour ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Wind ◽  
Sea Surface ◽  
Cumulus Convection ◽  
Warm Core ◽  
Projected Change

Abstract. This study focuses on a single Mediterranean hurricane (hearafter medicane), to investigate the medicane response to global warming during the middle of the 21st century and assess the contradictory effects of a warmer ocean and a warmer atmosphere on its development. Our investigation uses the state-of-the-art regional climate model WRF with the optimum combination of physical parameterizations based on a sensitivity assessment study. Results show that our model setup can reproduce a realistic cyclone track and the transition from initial disturbance to tropical-like cyclone with a deep warm core although the transition is earlier than for the observed medicane. To investigate the response of the medicane to future climate change, a pseudo global warming (PGW) approach has been used. This approach adds the projected change of atmospheric and ocean variables obtained by an ensemble of CMIP5 models to the boundary conditions for the regional climate model. A PGW simulation where all variables (PGWALL) are incremented shows that most of the medicane characteristics moderately intensify, e.g., surface wind speed, uptake of water vapour and precipitation. However the maximum depression of sea level pressure (SLP) is almost identical with that under present climate conditions. Two additional PGW simulations were undertaken; One simulation adds the projected change in sea surface and skin temperature only (PGWSST) while the second simulation adds the PGW changes to only atmospheric variables (PGWATMS) i.e. we use present time sea surface temperatures. These simulations show opposite effects on the medicane. In PGWSST, the medicane is reinforced more vigorously than PGWALL: much deeper SLP depression, stronger surface wind, and more intense evaporation and precipitation. In contrast, the medicane in PGWATMS weakens considerably (SLP, surface wind and rainfall decrease) still converts into a tropical-like cyclone with a deep warm core. This difference can be explained by an increased water vapour driven by the warmer ocean surface (favourable for cumulus convection) and the warmer and drier atmosphere in PGWATMS tends to inhibit condensation (unfavourable for cumulus convection). As a result of these counteracting effects of warmer ocean and atmosphere, the medicane is enhanced only modestly by global warming.

Methodology of Climate Change Impact Assessment on Forests

2019 ◽  
pp. 200-219
Author(s):  
Mostafa Jafari
Keyword(s):  
Climate Change ◽  
Time Series ◽  
Global Warming ◽  
Human Life ◽  
Future Climate Change ◽  
Present Climate ◽  
Climate Data ◽  
Empirical Observation ◽  
Climate Change Impact Assessment ◽  
Change Impact

Climate change is one of the challenging issues in various countries. Climate change and climate variability and global warming and its effects on natural resources, plants, animals, and on human life are among the subjects that received the attention of scientists and politicians in recent years. Climate change challenges need to be considered in various dimensions. To both understand the present climate and to predict future climate change, it is necessary to have both theory and empirical observation. Any study of climate change involves the construction (or reconstruction) of time series of climate data. How these climate data vary across time provides a measure (either quantitative or qualitative) of climate change. Types of climate data include temperature, precipitation (rainfall), wind, humidity, evapotranspiration, pressure, and solar irradiance. This chapter explores a methodology of measuring climate change's impact on forests.

scholarly journals Robust increase of Indian monsoon rainfall and its variability under future warming in CMIP-6 models

2020 ◽  
Author(s):  
Anja Katzenberger ◽  
Jacob Schewe ◽  
Julia Pongratz ◽  
Anders Levermann
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Climate Models ◽  
Monsoon Rainfall ◽  
Global Climate ◽  
Coupled Model ◽  
Global Climate Models ◽  
Future Climate Change ◽  
Global Mean Temperature ◽  
Almost All

Abstract. The Indian summer monsoon is an integral part of the global climate system. As its seasonal rainfall plays a crucial role in India's agriculture and shapes many other aspects of life, it affects the livelihood of a fifth of the world's population. It is therefore highly relevant to assess its change under potential future climate change. Global climate models within the Coupled Model Intercomparison Project Phase 5 (CMIP-5) indicated a consistent increase in monsoon rainfall and its variability under global warming. Since the range of the results of CMIP-5 was still large and the confidence in the models was limited due to partly poor representation of observed rainfall, the updates within the latest generation of climate models in CMIP-6 are of interest. Here, we analyse 32 models of the latest CMIP-6 exercise with regard to their annual mean monsoon rainfall and its variability. All of these models show a substantial increase in June-to-September (JJAS) mean rainfall under unabated climate change (SSP5-8.5) and most do also for the other three Shared Socioeconomic Pathways analyzed (SSP1-2.6, SSP2-4.5, SSP3-7.0). Moreover, the simulation ensemble indicates a linear dependence of rainfall on global mean temperature with high agreement between the models and independent of the SSP; the multi-model mean for JJAS projects an increase of 0.33 mm/day and 5.3 % per degree of global warming. This is significantly higher than in the CMIP-5 projections. Most models project that the increase will contribute to the precipitation especially in the Himalaya region and to the northeast of the Bay of Bengal, as well as the west coast of India. Interannual variability is found to be increasing in the higher-warming scenarios by almost all models. The CMIP-6 simulations largely confirm the findings from CMIP-5 models, but show an increased robustness across models with reduced uncertainties and updated magnitudes towards a stronger increase in monsoon rainfall.

scholarly journals Arctic Sea Ice’s Amplification as a Complement to Anthropogenic Global Warming

2021 ◽  
Author(s):  
Marco Morando
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Sea Ice ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Future Climate Change ◽  
Number Count ◽  
Anthropogenic Global Warming ◽  
Arctic Sea ◽  
Scientific Subject

Abstract Climate Change is a widely debated scientific subject and Anthropogenic Global Warming is its main cause. Nevertheless, several authors have indicated solar activity and Atlantic Multi-decadal Oscillation variations may also influence Climate Change. This article considers the amplification of solar radiation’s and Atlantic Multi-decadal Oscillation’s variations, via sea ice cover albedo feedbacks in the Arctic regions, providing a conceptual advance in the application of Arctic Amplification for modelling historical climate change. A 1-dimensional physical model, using sunspot number count and Atlantic Multi-decadal Oscillation index as inputs, can simulate the average global temperature’s anomaly and the Arctic Sea Ice Extension for the past eight centuries. This model represents an innovative progress in understanding how existing studies on Arctic sea ice’s albedo feedbacks can help complementing the Anthropogenic Global Warming models, thus helping to define more precise models for future climate change.

When did We Start to Change Things?

2009 ◽  
Author(s):  
Thomas N. Sherratt ◽  
David M. Wilkinson
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Science Fiction ◽  
Early Summer ◽  
Current Evidence ◽  
Future Climate Change ◽  
Worst Case ◽  
History Of ◽  
The Subject ◽  
James Lovelock

As we wrote the first draft of this chapter (during early summer 2007), the potential dangers of ‘global warming’ had moved up the news agenda to a point where most major politicians were starting to take the problem seriously. Our opening quotation comes from a book published in early 2006, which seemed to coincide with the growth of this wider concern with global warming. Lovelock was not alone in trying to raise awareness of the problem; around the same time another book on climate change by the zoologist and palaeontologist Tim Flannery also attracted global attention to this issue, as did the lecture tours (and Oscar-winning film) of Al Gore—the former US presidential candidate and campaigner on the dangers of climate change. Indeed, in his role as a climate campaigner Gore won a share in the 2007 Nobel Peace Prize. It is possible that future historians will see the period 2005–2007 as the start of a crucial wider engagement with these problems. Things may not be as bad as James Lovelock suggests—in his book he deliberately emphasized the most worrying scenarios coming from computer models, and other evidence, in an attempt to draw attention to the critical nature of the problem. However, all these worst case scenarios were drawn from within the range of results that most climate scientists believed could plausibly happen—not extreme cases with little current evidence to support them. That one of the major environmental scientists of the second half of the twentieth century could write such prose as science—rather than science fiction—is clearly a case for concern about future climate change. It also raises another important question, relating to the history of human influence on our planet: when in our history did we start to have major environmental impacts on Earth as a whole? This is clearly an important issue from a historical perspective, but the answers may also have implications for some of our attempts to rectify the damage. Our discussion of this question comes with various caveats. Many of the arguments we consider in this chapter are still the subject of academic disagreement.

Reevaluation of Design Waves Off the Western Indian Coast Considering Climate Change

2016 ◽  
Vol 50 (1) ◽  
pp. 88-98 ◽  
Author(s):  
Pentapati Satyavathi ◽  
Makarand C. Deo ◽  
Jyoti Kerkar ◽  
Ponnumony Vethamony
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
General Circulation ◽  
Generalized Pareto Distribution ◽  
Circulation Model ◽  
Offshore Structures ◽  
Future Climate Change ◽  
Extreme Value Analysis ◽  
Value Analysis ◽  
Wave Data

AbstractKnowledge of design waves with long return periods forms an essential input to many engineering applications, including structural design and analysis. Such extreme or long-term waves are conventionally evaluated using observed or hindcast historical wave data. Globally, waves are expected to undergo future changes in magnitude and behavior as a result of climate change induced by global warming. Considering future climate change, this study attempts to reevaluate significant wave height (Hs) as well as average spectral wave period (Tz) with a return period of 100 years for a series of locations along the western Indian coastline. Historical waves are simulated using a numerical wave model forced by wind data extracted from the archives of the National Center for Environmental Prediction and the National Center for Atmospheric Research, while future wave data are generated by a state-of-the-art Canadian general circulation model. A statistical extreme value analysis of past and projected wave data carried out with the help of the generalized Pareto distribution showed an increase in 100-year Hs and Tz along the Indian coastline, pointing out the necessity to reconsider the safety of offshore structures in the light of global warming.

scholarly journals Changes to the tropical circulation in the mid-Pliocene and their implications for future climate

2017 ◽  
Vol 13 (2) ◽  
pp. 135-147 ◽  
Author(s):  
Shawn Corvec ◽  
Christopher G. Fletcher
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Hadley Circulation ◽  
Walker Circulation ◽  
Tropical Indian Ocean ◽  
Future Climate ◽  
Sea Surface ◽  
Future Climate Change ◽  
Overturning Circulation ◽  
Future Projections

Abstract. The two components of the tropical overturning circulation, the meridional Hadley circulation (HC) and the zonal Walker circulation (WC), are key to the re-distribution of moisture, heat and mass in the atmosphere. The mid-Pliocene Warm Period (mPWP; ∼ 3.3–3 Ma) is considered a very rough analogue of near-term future climate change, yet changes to the tropical overturning circulations in the mPWP are poorly understood. Here, climate model simulations from the Pliocene Model Intercomparison Project (PlioMIP) are analyzed to show that the tropical overturning circulations in the mPWP were weaker than preindustrial circulations, just as they are projected to be in future climate change. The weakening HC response is consistent with future projections, and its strength is strongly related to the meridional gradient of sea surface warming between the tropical and subtropical oceans. The weakening of the WC is less robust in PlioMIP than in future projections, largely due to inter-model variations in simulated warming of the tropical Indian Ocean (TIO). When the TIO warms faster (slower) than the tropical mean, local upper tropospheric divergence increases (decreases) and the WC weakens less (more). These results provide strong evidence that changes to the tropical overturning circulation in the mPWP and future climate are primarily controlled by zonal (WC) and meridional (HC) gradients in tropical–subtropical sea surface temperatures.

scholarly journals Simulating climate warming scenarios with intentionally biased bootstrapping and its implications for precipitation

2016 ◽  
Author(s):  
Taesam Lee
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Sampling Technique ◽  
Good Alternative ◽  
Future Climate ◽  
Future Climate Change ◽  
Precipitation Data ◽  
Temperature Variable ◽  
Temperature Scenario ◽  
Hydrological Variables

Abstract. The outputs from GCMs provide useful information about the rate and magnitude of future climate change. The temperature variable is the most reliable of the GCM outputs. However, hydrological variables (e.g., precipitation) from GCM outputs for future climate change possess an uncertainty that is too high for practical use. Therefore, a method, called intentionally biased bootstrapping (IBB), that simulates the increase of the temperature variable by a certain level as ascertained from observed global warming data is proposed. In addition, precipitation data was resampled by employing a block-wise sampling technique associated with the temperature simulation. In summary, a warming temperature scenario is simulated and the corresponding precipitation values whose time indices are the same as the one of the simulated warming temperature scenario. The proposed method was validated with annual precipitation data by truncating the recent years of the record. The proposed model was also employed to assess the future changes in seasonal precipitation in South Korea within a global warming scenario as well as in weekly time scale. The results illustrate that the proposed method is a good alternative for assessing the variation of hydrological variables such as precipitation under the warming condition.

scholarly journals Analysis and Comparison of Spatial–Temporal Entropy Variability of Tehran City Microclimate Based on Climate Change Scenarios

Entropy ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 13 ◽  
Author(s):  
Abdolazim Ghanghermeh ◽  
Gholamreza Roshan ◽  
José Orosa ◽  
Ángel Costa
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Shannon Entropy ◽  
Temperature Difference ◽  
Effective Temperature ◽  
Urban Climate ◽  
Temporal Variations ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Local Pressure

Urban microclimate patterns can play a great role for the allocation and management of cooling and heating energy sources, urban design and architecture, and urban heat island control. Therefore, the present study intends to investigate the variability of spatial and temporal entropy of the Effective Temperature index (ET) for the two basic periods (1971–2010) and the future (2011–2050) in Tehran to determine how the variability degree of the entropy values of the abovementioned bioclimatic would be, based on global warming and future climate change. ArcGIS software and geostatistical methods were used to show the Spatial and Temporal variations of the microclimate pattern in Tehran. However, due to global warming the temperature difference between the different areas of the study has declined, which is believed to reduce the abnormalities and more orderly between the data spatially and over time. It is observed that the lowest values of the Shannon entropy occurred in the last two decades, from 2030 to 2040, and the other in 2040–2050. Because, based on global warming, dominant areas have increased temperature, and the difference in temperature is reduced daily and the temperature difference between the zones of different areas is lower. The results of this study show a decrease in the coefficient of the Shannon entropy of effective temperature for future decades in Tehran. This can be due to the reduction of temperature differences between different regions. However, based on the urban-climate perspective, there is no positive view of this process. Because reducing the urban temperature difference means reducing the local pressure difference as well as reducing local winds. This is a factor that can effective, though limited, in the movement of stagnant urban air and reduction of thermal budget and thermal stress of the city.

scholarly journals Changes to the tropical circulation in the mid-Pliocene and their implications for future climate

2016 ◽  
Author(s):  
Shawn Corvec ◽  
Christopher G. Fletcher
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Hadley Circulation ◽  
Walker Circulation ◽  
Tropical Indian Ocean ◽  
Future Climate ◽  
Sea Surface ◽  
Future Climate Change ◽  
Overturning Circulation ◽  
Future Projections

Abstract. The two components of the tropical overturning circulation, the meridional Hadley circulation (HC) and the zonal Walker circulation (WC), are key to the re-distribution of moisture, heat and mass in the atmosphere. The mid-Pliocene Warm Period (mPWP; ∼3–3.3 MY BP) is considered a useful analogue of near-term future climate change, yet changes to the tropical overturning circulations in the mPWP are poorly understood. Here, climate model simulations from the Pliocene Model Intercomparison Project (PlioMIP) are analyzed to show that the tropical overturning circulations in the mPWP were weaker than pre-industrial, just as they are projected to be in future climate change. The weakening HC response is consistent with future projections, and its strength is strongly related to the meridional gradient of sea surface warming between the tropical and subtropical oceans. The weakening of the WC is less robust in PlioMIP than in future projections, largely due to intermodel variations in simulated warming of the tropical Indian Ocean (TIO). When the TIO warms faster (slower) than the tropical mean, local upper tropospheric divergence increases (decreases) and the WC weakens less (more). These results provide strong evidence that changes to the tropical overturning circulation in the mPWP and future climate are primarily controlled by zonal (WC) and meridional (HC) gradients in tropical-subtropical sea surface temperatures.

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