scholarly journals Statistical–Dynamical Downscaling Projections of Tropical Cyclone Activity in a Warming Climate: Two Diverging Genesis Scenarios

2020 ◽  
Vol 33 (11) ◽  
pp. 4815-4834 ◽  
Author(s):  
Chia-Ying Lee ◽  
Suzana J. Camargo ◽  
Adam H. Sobel ◽  
Michael K. Tippett
Keyword(s):  
Tropical Cyclone ◽  
Environmental Conditions ◽  
Dynamical Downscaling ◽  
Coupled Model ◽  
Historical Period ◽  
Future Scenario ◽  
Warming Climate ◽  
Increasing Trend ◽  
The Future ◽  
Intercomparison Project

AbstractTropical cyclone (TC) activity is examined using the Columbia Hazard model (CHAZ), a statistical–dynamical downscaling system, with environmental conditions taken from simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) for both the historical period and a future scenario under the representative concentration pathway 8.5. Projections of individual global and basin TC frequency depend sensitively on the choice of moisture variable used in the tropical genesis cyclone index (TCGI) component of CHAZ. Simulations using column relative humidity show an increasing trend in the future, while those using saturation deficit show a decreasing trend, although both give similar results in the historical period. While the projected annual TC frequency is also sensitive to the choice of model used to provide the environmental conditions, the choice of humidity variable in the TCGI is more important. Changes in TC frequency directly affect the projected TCs’ tracks and the frequencies of strong storms on both basin and regional scales. This leads to large uncertainty in assessing regional and local storm hazards. The uncertainty here is fundamental and epistemic in nature. Increases in the fraction of major TCs, rapid intensification rate, and decreases in forward speed are insensitive to TC frequency, however. The present results are also consistent with prior studies in indicating that those TC events that do occur will, on average, be more destructive in the future because of the robustly projected increases in intensity.

scholarly journals Past and future changes of streamflow in Poyang Lake Basin, Southeastern China

2012 ◽  
Vol 16 (7) ◽  
pp. 2005-2020 ◽  
Author(s):  
S. L. Sun ◽  
H. S. Chen ◽  
W. M. Ju ◽  
J. Song ◽  
J. J. Li ◽  
...  
Keyword(s):  
Poyang Lake ◽  
Water Cycle ◽  
Coupled Model ◽  
Soil Water Storage ◽  
Future Climate Change ◽  
Lake Basin ◽  
Poyang Lake Basin ◽  
The Future ◽  
Intercomparison Project ◽  
Meteorological Observations

Abstract. To understand the causes of the past water cycle variations and the influence of climate variability on the streamflow, lake storage, and flood potential, we analyze the changes in streamflow and the underlying drivers in four typical watersheds (Gaosha, Meigang, Saitang, and Xiashan) within the Poyang Lake Basin, based on the meteorological observations at 79 weather stations, and datasets of streamflow and river level at four hydrological stations for the period of 1961-2000. The contribution of different climate factors to the change in streamflow in each watershed is estimated quantitatively using the water balance equations. Results show that in each watershed, the annual streamflow exhibits an increasing trend from 1961–2000. The increases in streamflow by 4.80 m3 s−1 yr−1 and 1.29 m3 s−1 yr−1 at Meigang and Gaosha, respectively, are statistically significant at the 5% level. The increase in precipitation is the biggest contributor to the streamflow increment in Meigang (3.79 m3 s−1 yr−1), Gaosha (1.12 m3 s−1 yr−1), and Xiashan (1.34 m3 s−1 yr−1), while the decrease in evapotranspiration is the major factor controlling the streamflow increment in Saitang (0.19 m3 s−1 yr−1). In addition, radiation and wind contribute more than actual vapor pressure and mean temperature to the changes in evapotranspiration and streamflow for the four watersheds. For revealing the possible change of streamflow due to the future climate change, we also investigate the projected precipitation and evapotranspiration from of the Coupled Model Intercomparison Project phase 3 (CMIP3) under three greenhouse gases emission scenarios (SRESA1B, SRESA2 and SRESB1) for the period of 2061–2100. When the future changes in the soil water storage changes are assumed ignorable, the streamflow shows an uptrend with the projected increases in both precipitation and evapotranspiration (except for the SRESB1 scenario in Xiashan watershed) relative to the observed mean during 1961–2000. Furthermore, the largest increase in the streamflow is found at Meigang (+4.31%) and Xiashan (+3.84%) under the SRESA1B scenario, while the increases will occur at Saitang (+6.87%) and Gaosha (+5.15%) under the SRESB1 scenario.

Decomposition of Future Moisture Flux Changes over the Tibetan Plateau Projected by Global and Regional Climate Models

2019 ◽  
Vol 32 (20) ◽  
pp. 7037-7053
Author(s):  
Hongwen Zhang ◽  
Yanhong Gao ◽  
Jianwei Xu ◽  
Yu Xu ◽  
Yingsha Jiang
Keyword(s):  
Tibetan Plateau ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Moisture Flux ◽  
Historical Period ◽  
The Tibetan Plateau ◽  
Dynamic Component ◽  
Coarse Resolution ◽  
The Future

Abstract To meet the requirement of high-resolution datasets for many applications, a dynamical downscaling approach using a regional climate model (the WRF Model) driven by a global climate model (CCSM4) has been adopted. This study focuses on projections of future moisture flux changes over the Tibetan Plateau (TP). First, the downscaling results for the historical period (1980–2005) are evaluated for precipitation P, evaporation E, and precipitation minus evaporation P − E against Global Land Data Assimilation System (GLDAS) data. The mechanism of P − E changes is analyzed by decomposition into dynamic, thermodynamic, and transient eddy components. Whether the historical period changes and mechanisms continue into the future (2010–2100) is investigated using the WRF and CCSM model projections under the RCP4.5 and RCP8.5 scenarios. Compared with coarse-resolution forcing, downscaling was found to better reproduce the historical spatial patterns and seasonal mean of annual average P, E, and P − E over the TP. WRF projects a diverse spatial variation of P − E changes, with an increase in the northern TP and a decrease in the southern TP, compared with the uniform increase in CCSM. The dynamic component dominates P − E changes for the historical period in both the CCSM and WRF projections. In the future, however, the thermodynamic component in CCSM dominates P − E changes under RCP4.5 and RCP8.5 from the near-term (2010–39) to the long-term (2070–99) future. Unlike the CCSM projections, the WRF projections reproduce the mechanism seen in the historical period—that is, the dynamic component dominates P − E changes. Furthermore, future P − E changes in the dynamical downscaling are less sensitive to warming than its coarse-resolution forcing.

scholarly journals AerChemMIP: quantifying the effects of chemistry and aerosols in CMIP6

2017 ◽  
Vol 10 (2) ◽  
pp. 585-607 ◽  
Author(s):  
William J. Collins ◽  
Jean-François Lamarque ◽  
Michael Schulz ◽  
Olivier Boucher ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Air Quality ◽  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Climate Models ◽  
Coupled Model ◽  
Climate Impacts ◽  
Atmospheric Composition ◽  
Historical Period ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract. The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) is endorsed by the Coupled-Model Intercomparison Project 6 (CMIP6) and is designed to quantify the climate and air quality impacts of aerosols and chemically reactive gases. These are specifically near-term climate forcers (NTCFs: methane, tropospheric ozone and aerosols, and their precursors), nitrous oxide and ozone-depleting halocarbons. The aim of AerChemMIP is to answer four scientific questions. 1. How have anthropogenic emissions contributed to global radiative forcing and affected regional climate over the historical period? 2. How might future policies (on climate, air quality and land use) affect the abundances of NTCFs and their climate impacts? 3.How do uncertainties in historical NTCF emissions affect radiative forcing estimates? 4. How important are climate feedbacks to natural NTCF emissions, atmospheric composition, and radiative effects? These questions will be addressed through targeted simulations with CMIP6 climate models that include an interactive representation of tropospheric aerosols and atmospheric chemistry. These simulations build on the CMIP6 Diagnostic, Evaluation and Characterization of Klima (DECK) experiments, the CMIP6 historical simulations, and future projections performed elsewhere in CMIP6, allowing the contributions from aerosols and/or chemistry to be quantified. Specific diagnostics are requested as part of the CMIP6 data request to highlight the chemical composition of the atmosphere, to evaluate the performance of the models, and to understand differences in behaviour between them.

scholarly journals Dynamical Downscaling Projections of Twenty-First-Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-Based Scenarios

2013 ◽  
Vol 26 (17) ◽  
pp. 6591-6617 ◽  
Author(s):  
Thomas R. Knutson ◽  
Joseph J. Sirutis ◽  
Gabriel A. Vecchi ◽  
Stephen Garner ◽  
Ming Zhao ◽  
...  
Keyword(s):  
Inner Core ◽  
Dynamical Downscaling ◽  
Coupled Model ◽  
First Century ◽  
Cmip5 Models ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Hurricane Activity ◽  
Twenty First Century

Abstract Twenty-first-century projections of Atlantic climate change are downscaled to explore the robustness of potential changes in hurricane activity. Multimodel ensembles using the phase 3 of the Coupled Model Intercomparison Project (CMIP3)/Special Report on Emissions Scenarios A1B (SRES A1B; late-twenty-first century) and phase 5 of the Coupled Model Intercomparison Project (CMIP5)/representative concentration pathway 4.5 (RCP4.5; early- and late-twenty-first century) scenarios are examined. Ten individual CMIP3 models are downscaled to assess the spread of results among the CMIP3 (but not the CMIP5) models. Downscaling simulations are compared for 18-km grid regional and 50-km grid global models. Storm cases from the regional model are further downscaled into the Geophysical Fluid Dynamics Laboratory (GFDL) hurricane model (9-km inner grid spacing, with ocean coupling) to simulate intense hurricanes at a finer resolution. A significant reduction in tropical storm frequency is projected for the CMIP3 (−27%), CMIP5-early (−20%) and CMIP5-late (−23%) ensembles and for 5 of the 10 individual CMIP3 models. Lifetime maximum hurricane intensity increases significantly in the high-resolution experiments—by 4%–6% for CMIP3 and CMIP5 ensembles. A significant increase (+87%) in the frequency of very intense (categories 4 and 5) hurricanes (winds ≥ 59 m s−1) is projected using CMIP3, but smaller, only marginally significant increases are projected (+45% and +39%) for the CMIP5-early and CMIP5-late scenarios. Hurricane rainfall rates increase robustly for the CMIP3 and CMIP5 scenarios. For the late-twenty-first century, this increase amounts to +20% to +30% in the model hurricane’s inner core, with a smaller increase (~10%) for averaging radii of 200 km or larger. The fractional increase in precipitation at large radii (200–400 km) approximates that expected from environmental water vapor content scaling, while increases for the inner core exceed this level.

scholarly journals The GRISLI-LSCE contribution to the Ice Sheet Model Intercomparison Project for phase 6 of the Coupled Model Intercomparison Project (ISMIP6) – Part 1: Projections of the Greenland ice sheet evolution by the end of the 21st century

2021 ◽  
Vol 15 (2) ◽  
pp. 1015-1030 ◽  
Author(s):  
Aurélien Quiquet ◽  
Christophe Dumas
Keyword(s):  
Mass Loss ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Coupled Model ◽  
Greenland Ice Sheet ◽  
Model Intercomparison ◽  
The Future ◽  
Intercomparison Project ◽  
Global Sea Level

Abstract. Polar amplification will result in amplified temperature changes in the Arctic with respect to the rest of the globe, making the Greenland ice sheet particularly vulnerable to global warming. While the ice sheet has been showing an increased mass loss in the past decades, its contribution to global sea level rise in the future is of primary importance since it is at present the largest single-source contribution after the thermosteric contribution. The question of the fate of the Greenland and Antarctic ice sheets for the next century has recently gathered various ice sheet models in a common framework within the Ice Sheet Model Intercomparison Project for the Coupled Model Intercomparison Project – phase 6 (ISMIP6). While in a companion paper we present the GRISLI-LSCE (Grenoble Ice Sheet and Land Ice model of the Laboratoire des Sciences du Climat et de l'Environnement) contribution to ISMIP6-Antarctica, we present here the GRISLI-LSCE contribution to ISMIP6-Greenland. We show an important spread in the simulated Greenland ice loss in the future depending on the climate forcing used. The contribution of the ice sheet to global sea level rise in 2100 can thus be from as low as 20 mm sea level equivalent (SLE) to as high as 160 mm SLE. Amongst the models tested in ISMIP6, the Coupled Model Intercomparison Project – phase 6 (CMIP6) models produce larger ice sheet retreat than their CMIP5 counterparts. Low-emission scenarios in the future drastically reduce the ice mass loss. The oceanic forcing contributes to about 10 mm SLE in 2100 in our simulations. In addition, the dynamical contribution to ice thickness change is small compared to the impact of surface mass balance. This suggests that mass loss is mostly driven by atmospheric warming and associated ablation at the ice sheet margin. With additional sensitivity experiments we also show that the spread in mass loss is only weakly affected by the choice of the ice sheet model mechanical parameters.

scholarly journals Compiled records of carbon isotopes in atmospheric CO<sub>2</sub> for historical simulations in CMIP6

2017 ◽  
Author(s):  
Heather Graven ◽  
Colin E. Allison ◽  
David M. Etheridge ◽  
Samuel Hammer ◽  
Ralph F. Keeling ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Carbon Isotopes ◽  
Coupled Model ◽  
Atmospheric Co2 ◽  
Historical Period ◽  
Terrestrial Biosphere ◽  
Climate Simulations ◽  
Intercomparison Project ◽  
Natural Carbon ◽  
Carbon Cycle Modelling

Abstract. The isotopic composition of carbon (Δ14C and δ13C) in atmospheric CO2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14C and 13C in the ocean and terrestrial components of Earth System Models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of Δ14C and δ13C in atmospheric CO2 for the historical period 1850–2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in their ocean or terrestrial biosphere models. The data may also be useful for other carbon cycle modelling activities.

scholarly journals On the Mechanisms of Pacific Decadal Oscillation Modulation in a Warming Climate

2019 ◽  
Vol 32 (5) ◽  
pp. 1443-1459 ◽  
Author(s):  
Tao Geng ◽  
Yun Yang ◽  
Lixin Wu
Keyword(s):  
Growth Rate ◽  
Global Warming ◽  
Pacific Decadal Oscillation ◽  
Decadal Variability ◽  
Coupled Model ◽  
Growth Time ◽  
Coupled Mode ◽  
Warming Climate ◽  
The Pacific ◽  
Intercomparison Project

Abstract Changes of the Pacific decadal oscillation (PDO) under global warming are investigated by using outputs from phase 5 of the Coupled Model Intercomparison Project (CMIP5) and a theoretical midlatitude air–sea coupled model. In a warming climate, the decadal variability of the PDO is found to be significantly suppressed, with the amplitude reduced and the decadal cycle shifted toward a higher-frequency band. We used the theoretical model put forward by Goodman and Marshall (herein the GM model) to underpin the potential mechanisms. The GM model exhibits a growing coupled mode that resembles the simulated PDO. It is found that the suppression of the PDO appears to be associated with the acceleration of Rossby waves due to the enhanced oceanic stratification under global warming. This shortens the PDO period and reduces PDO amplitude by limiting the growth time of the coupled mode. The GM model also suggests that the increase of growth rate due to strengthening of oceanic stratification tends to magnify the PDO amplitude, counteracting the Rossby wave effect. This growth rate influence, however, plays a secondary role.

Simulation of wind damages associated with the PRIMAVERA European windstorm event set

2021 ◽  
Author(s):  
Tristan Perotin
Keyword(s):  
Climate Models ◽  
Dynamical Downscaling ◽  
Insurance Industry ◽  
Coupled Model ◽  
Correction Method ◽  
Weather Data ◽  
Cmip5 Models ◽  
Model Intercomparison ◽  
Insurance Sector ◽  
Intercomparison Project

&lt;p&gt;Winter windstorms are one of the major natural hazards affecting Europe, potentially causing large damages. The study of windstorm risks is therefore particularly important for the insurance industry. Physical natural catastrophe models for the insurance industry appeared in the 1980s and enable a fine analysis of the risk by taking into account all of its components (hazard, vulnerability and exposure). One main aspect of this catastrophe modeling is the production and validation of extreme hazard scenarios. As observational weather data is very sparse before the 1980s, estimates of extreme windstorm risks are usually based on climate models, despite the limited resolution of these models. Even though this limitation can be partially corrected by statistical or dynamical downscaling and calibration techniques, new generations of climate models can bring new understanding of windstorm risks.&lt;/p&gt;&lt;p&gt;In that context, PRIMAVERA, a European Union Horizon2020 project, made available a windstorm event set based on 21 tier 1 (1950-2014) highresSST-present simulations of the High Resolution Model Intercomparison Project (HighResMIP) component of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The events were identified with a storm tracking algorithm, footprints were defined for each event as maximum gusts over a 72 hour period, and the footprints were re-gridded to the ERA5 grid and calibrated with a quantile mapping correction method. The native resolution of these simulations ranges from 150km (typical resolution of the CMIP5 models) to 25km.&lt;/p&gt;&lt;p&gt;We have studied the applicability of the PRIMAVERA European windstorm event set for the modeling of European windstorm risks for the insurance sector. Preliminary results show that losses simulated from the event set appear to be consistent with historical data for all of the included simulations. The event set enables a better representation of attritional events and storm clustering than other existing event sets. An alternative calibration technique for extreme gusts and potential future developments of the event set will be proposed.&lt;/p&gt;

Weakening of the equatorial Atlantic SST variability under global warming

2021 ◽  
Author(s):  
Lander R. Crespo ◽  
Arthur Prigent ◽  
Noel Keenlyside ◽  
Ingo Richter ◽  
Emilia Sánchez-Gómez ◽  
...  
Keyword(s):  
Global Warming ◽  
Atlantic Ocean ◽  
Boreal Summer ◽  
Historical Period ◽  
Thermocline Depth ◽  
Equatorial Atlantic ◽  
Future Scenario ◽  
Sst Variability ◽  
Thermocline Feedback ◽  
The Future

&lt;p&gt;The eastern equatorial Atlantic is the region with the largest seasonal and interannual sea surface temperature (SST) variability in the entire tropical Atlantic Ocean. It is characterized by a rapid cooling during the boreal summer season, between June and September, that has large impacts in the regional climate. In this study we explore climate changes related to global warming in the cold tongue region using the CMIP5 and CMIP6 datasets as benchmarks. The historical simulations of both CMIP generations reproduce fairly well the spatial pattern of the observed warming &amp;#8211; although weaker &amp;#8211; in the Angola-Benguela region and most of the equatorial Atlantic band. The largest disagreements between model and observations are localized in the eastern equatorial Atlantic. The future business-as-usual scenario shows an intense and zonally homogeneous warming along the equatorial Atlantic band in CMIP5 and CMIP6. We also find a significant reduction of the June-July-August SST variability of 12% (17%) in the ensemble mean of the CMIP5 (CMIP6), in the future scenario (2050-2099) with respect to the historical period (1950-1999). The thermocline feedback, i.e., the local response of the SST anomalies to the thermocline depth anomalies, is weaker in the future scenario and appears to be the main driver of the change in interannual SST variability. The strong warming of the upper equatorial Atlantic Ocean in the future leads to a higher stratification which could explain the weaker thermocline feedback.&lt;/p&gt;

scholarly journals AerChemMIP: Quantifying the effects of chemistry and aerosols in CMIP6

2016 ◽  
Author(s):  
William J. Collins ◽  
Jean-François Lamarque ◽  
Michael Schulz ◽  
Olivier Boucher ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Air Quality ◽  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Climate Models ◽  
Coupled Model ◽  
Climate Impacts ◽  
Anthropogenic Emissions ◽  
Historical Period ◽  
Model Intercomparison ◽  
Intercomparison Project

Abstract. The Aerosol Chemistry Model Intercomparison Project (AerChemMIP) is endorsed by the Coupled-Model Intercomparison Project 6 (CMIP6) and is designed to quantify the climate and air quality impacts of aerosols and chemically-reactive gases. These are specifically near-term climate forcers (NTCFs: tropospheric ozone and aerosols, and their precursors), methane, nitrous oxide and ozone-depleting halocarbons. The aim of AerChemMIP is to answer four scientific questions: 1. How have anthropogenic emissions contributed to global radiative forcing and affected regional climate over the historical period? 2. How will future policies (on climate, air quality and land use) affect these species and their climate impacts? 3. Can the uncertainties associated with anthropogenic emissions be quantified? 4. Can climate feedbacks occurring through changes in natural emissions be quantified? These questions will be addressed through targeted simulations with CMIP6 climate models that include an interactive representation of tropospheric aerosols and atmospheric chemistry. These simulations build on the CMIP6 Diagnostic, Evaluation and Characterization of Klima (DECK) experiments, the CMIP6 historical simulations, and future projections performed elsewhere in CMIP6, allowing the contributions from aerosols and chemistry to be quantified. Specific diagnostics are requested as part of the CMIP6 data request to evaluate the performance of the models, and to understand any differences in behaviour between them.

Sign in / Sign up

Export Citation Format

Share Document