scholarly journals Projected Changes in the Southern Indian Ocean Cyclone Activity Assessed from High-Resolution Experiments and CMIP5 Models

2020 ◽  
Vol 33 (12) ◽  
pp. 4975-4991
Author(s):  
Julien Cattiaux ◽  
Fabrice Chauvin ◽  
Olivier Bousquet ◽  
Sylvie Malardel ◽  
Chia-Lun Tsai
Keyword(s):  
High Resolution ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Large Scale ◽  
Climate Model ◽  
Southern Indian Ocean ◽  
Cmip5 Models ◽  
Climate Projections ◽  
Cyclone Activity ◽  
Projected Changes

AbstractThe evolution of tropical cyclone activity under climate change remains a crucial scientific issue. Physical theory of cyclogenesis is limited, observational datasets suffer from heterogeneities in space and time, and state-of-the-art climate models used for future projections are still too coarse (~100 km of resolution) to simulate realistic systems. Two approaches can nevertheless be considered: 1) perform dedicated high-resolution (typically <50 km) experiments in which tropical cyclones can be tracked and 2) assess cyclone activity from existing low-resolution multimodel climate projections using large-scale indices as proxies. Here we explore these two approaches with a particular focus on the southern Indian Ocean. We first compute high-resolution experiments using the rotated-stretched configuration of our climate model (CNRM-CM6-1), which is able to simulate realistic tropical cyclones. In a 2-K warmer world, the model projects a 20% decrease in the frequency of tropical cyclones, together with an increase in their maximum lifetime intensity, a slight poleward shift of their trajectories, and a substantial delay (about 1 month) in the cyclone season onset. Large-scale indices applied to these high-resolution experiments fail to capture the overall decrease in cyclone frequency, but are able to partially represent projected changes in the spatiotemporal distribution of cyclone activity. Last, we apply large-scale indices to multimodel CMIP5 projections and find that the seasonal redistribution of cyclone activity is consistent across models.

Projected changes in tropical cyclone activity under future warming scenarios using a high-resolution climate model

2016 ◽  
Vol 146 (3-4) ◽  
pp. 547-560 ◽  
Author(s):  
Julio T. Bacmeister ◽  
Kevin A. Reed ◽  
Cecile Hannay ◽  
Peter Lawrence ◽  
Susan Bates ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
Climate Model ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity ◽  
Future Warming ◽  
Projected Changes

Potential Underestimation of Future Mei-Yu Rainfall with Coarse-Resolution Climate Models

2018 ◽  
Vol 31 (17) ◽  
pp. 6711-6727 ◽  
Author(s):  
Xiaolong Chen ◽  
Peili Wu ◽  
Malcolm J. Roberts ◽  
Tianjun Zhou
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Climate Models ◽  
Climate Model ◽  
Summer Rainfall ◽  
Climate Projections ◽  
Model Resolution ◽  
Low Resolution ◽  
Resolution Model ◽  
High Resolution Model

The amount of rainfall during June and July along the mei-yu front contributes about 45% to the total summer precipitation over the Yangtze River valley. How it will change under global warming is of great concern to the people of China because of its particular socioeconomic importance, but climate model projections from phase 5 of the Coupled Model Intercomparison Project (CMIP5) show large uncertainties. This paper examines model resolution sensitivity and reports large differences in projected future summer rainfall along the mei-yu front between a low-resolution (Gaussian N96 grid, ~1.5° latitude–longitude) and a high-resolution (N216, ~0.7°) version of the Hadley Centre’s latest climate model, the HadGEM3 Global Coupled Configuration 2.0 (HadGEM3-GC2). The high-resolution model projects large increases of summer rainfall under two representative concentration pathway scenarios (RCP8.5 and RCP4.5) whereas the low-resolution model shows a decrease. A larger increase of projected mei-yu rainfall in higher-resolution models is also observed across the CMIP5 ensemble. These differences can be explained in terms of enhanced moist static energy advection and moisture convergence by stationary eddies in the high-resolution model. A large-scale manifestation of the anomalous stationary eddies is the contrasting response to the same warming scenario by the western North Pacific subtropical high, which is almost unchanged in N216 but retreats evidently eastward in N96, reducing the southwesterly flow and consequently moisture supply to the mei-yu front. Further increases in model resolution to resolve parameterized processes and detailed orographic features will hopefully reduce the spread in future climate projections.

scholarly journals The Effect of Regional Climate Model Domain Choice on the Simulation of Tropical Cyclone–Like Vortices in the Southwestern Indian Ocean

2005 ◽  
Vol 18 (8) ◽  
pp. 1263-1274 ◽  
Author(s):  
Willem A. Landman ◽  
Anji Seth ◽  
Suzana J. Camargo
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Regional Climate Model ◽  
Tropical Cyclones ◽  
Large Scale ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Model ◽  
Model Domain ◽  
Southwestern Indian Ocean

Abstract A regional climate model is tested for several domain configurations over the southwestern Indian Ocean to examine the ability of the model to reproduce observed cyclones and their landfalling tracks. The interaction between large-scale and local terrain forcing of tropical storms approaching and transiting the island landmass of Madagascar makes the southwestern Indian Ocean a unique and interesting study area. In addition, tropical cyclones across the southern Indian Ocean are likely to be significantly affected by the large-scale zonal flow. Therefore, the effects of model domain size and the positioning of its lateral boundaries on the simulation of tropical cyclone–like vortices and their tracks on a seasonal time scale are investigated. Four tropical cyclones, which occurred over the southwestern Indian Ocean in January of the years 1995–97, are studied, and four domains are tested. The regional climate model is driven by atmospheric lateral boundary conditions that are derived from large-scale meteorological analyses. The use of analyzed boundary forcing enables comparison with observed cyclones in these tests. Simulations are performed using a 60-km horizontal resolution and for an extended time integration of about 6 weeks. Results show that the positioning of the eastern boundary of the regional model domain is of major importance in the life cycle of simulated tropical cyclone–like vortices: a vortex entering through the eastern boundary of the regional model is generally well simulated. The size of the domain also has a bearing on the ability of the regional model to simulate vortices in the Mozambique Channel, and the island landmass of Madagascar additionally influences storm tracks. These results show that the regional model can produce cyclonelike vortices and their tracks (with some deficiencies) given analyzed lateral boundary forcing. Statistical analyses of GCM-driven nested model ensemble integrations are now required to further address predictive skill of cyclones in the southwestern Indian Ocean and to test if the model can realistically simulate tropical storm genesis as opposed to advecting existing tropical disturbances entering through the model boundaries.

scholarly journals Effect of Upper-Ocean Evolution on Projected Trends in Tropical Cyclone Activity

2015 ◽  
Vol 28 (20) ◽  
pp. 8165-8170 ◽  
Author(s):  
Kerry Emanuel
Keyword(s):  
Tropical Cyclone ◽  
Climate Models ◽  
Climate Model ◽  
Thermal Structure ◽  
Tropical Cyclone Activity ◽  
Cmip5 Models ◽  
Upper Ocean ◽  
Cyclone Activity ◽  
Climate Model Simulations ◽  
Projected Changes

Abstract Recent work has highlighted the possible importance of changing upper-ocean thermal and density stratification on observed and projected changes in tropical cyclone activity. Here seven CMIP phase 5 (CMIP5)-generation climate model simulations are downscaled under IPCC representative concentration pathway 8.5 using a coupled atmosphere–ocean tropical cyclone model, generating 100 events per year in the western North Pacific from 2006 to 2100. A control downscaling in which the upper-ocean thermal structure is fixed at its monthly values in the year 2006 is compared to one in which the upper ocean is allowed to evolve, as derived from the CMIP5 models. As found in earlier work, the thermal stratification generally increases as the climate warms, leading to increased ocean mixing–induced negative feedback on tropical cyclone intensity. While trends in the frequency of storms are unaffected, the increasing stratification of the upper ocean leads to a 13% reduction in the increase of tropical cyclone power dissipation over the twenty-first century, averaged across the seven climate models. Much of this reduction is associated with a moderation of the increase in the frequency of category-5 storms.

scholarly journals Response of Global Tropical Cyclone Activity to Increasing CO2: Results from Downscaling CMIP6 Models

2021 ◽  
Vol 34 (1) ◽  
pp. 57-70 ◽  
Author(s):  
Kerry Emanuel
Keyword(s):  
Tropical Cyclone ◽  
Greenhouse Gases ◽  
Tropical Cyclones ◽  
Climate Models ◽  
Climate Model ◽  
Tropical Cyclone Activity ◽  
Cmip5 Models ◽  
Cyclone Activity ◽  
The North ◽  
Sixth Generation

AbstractGlobal models comprising the sixth-generation Coupled Climate Model Intercomparison Project (CMIP6) are downscaled using a very high-resolution but simplified coupled atmosphere–ocean tropical cyclone model, as a means of estimating the response of global tropical cyclone activity to increasing greenhouse gases. As with a previous downscaling of CMIP5 models, the results show an increase in both the frequency and severity of tropical cyclones, robust across the models downscaled, in response to increasing greenhouse gases. The increase is strongly weighted to the Northern Hemisphere, and especially noteworthy is a large increase in the higher latitudes of the North Atlantic. Changes are insignificant in the South Pacific across metrics. Although the largest increases in track density are far from land, substantial increases in global landfalling power dissipation are indicated. The incidence of rapid intensification increases rapidly with warming, as predicted by existing theory. Measures of robustness across downscaled climate models are presented, and comparisons to tropical cyclones explicitly simulated in climate models are discussed.

scholarly journals Response of Tropical Cyclones to Idealized Climate Change Experiments in a Global High-Resolution Coupled General Circulation Model

2013 ◽  
Vol 26 (20) ◽  
pp. 7966-7980 ◽  
Author(s):  
Ray Bell ◽  
Jane Strachan ◽  
Pier Luigi Vidale ◽  
Kevin Hodges ◽  
Malcolm Roberts
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
General Circulation ◽  
Large Scale ◽  
Vertical Wind Shear ◽  
Circulation Model ◽  
Walker Circulation ◽  
Tropical Cyclone Activity ◽  
Cyclone Activity

Abstract The authors present an assessment of how tropical cyclone activity might change owing to the influence of increased atmospheric carbon dioxide concentrations, using the U.K. High-Resolution Global Environment Model (HiGEM) with N144 resolution (~90 km in the atmosphere and ~40 km in the ocean). Tropical cyclones are identified using a feature-tracking algorithm applied to model output. Tropical cyclones from idealized 30-yr 2×CO2 (2CO2) and 4×CO2 (4CO2) simulations are compared to those identified in a 150-yr present-day simulation that is separated into a five-member ensemble of 30-yr integrations. Tropical cyclones are shown to decrease in frequency globally by 9% in the 2CO2 and 26% in the 4CO2. Tropical cyclones only become more intense in the 4CO2; however, uncoupled time slice experiments reveal an increase in intensity in the 2CO2. An investigation into the large-scale environmental conditions, known to influence tropical cyclone activity in the main development regions, is used to determine the response of tropical cyclone activity to increased atmospheric CO2. A weaker Walker circulation and a reduction in zonally averaged regions of updrafts lead to a shift in the location of tropical cyclones in the Northern Hemisphere. A decrease in mean ascent at 500 hPa contributes to the reduction of tropical cyclones in the 2CO2 in most basins. The larger reduction of tropical cyclones in the 4CO2 arises from further reduction of the mean ascent at 500 hPa and a large enhancement of vertical wind shear, especially in the Southern Hemisphere, North Atlantic, and northeast Pacific.

scholarly journals Comparison of regional characteristics of land precipitation climatology projected by an MRI-AGCM multi-cumulus scheme and multi-SST ensemble with CMIP5 multi-model ensemble projections

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Rui Ito ◽  
Tosiyuki Nakaegawa ◽  
Izuru Takayabu
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
General Circulation ◽  
Annual Precipitation ◽  
Cmip5 Models ◽  
Climate Projections ◽  
The Tibetan Plateau ◽  
Model Ensemble ◽  
Uncertainty Range ◽  
High Performing

AbstractEnsembles of climate change projections created by general circulation models (GCMs) with high resolution are increasingly needed to develop adaptation strategies for regional climate change. The Meteorological Research Institute atmospheric GCM version 3.2 (MRI-AGCM3.2), which is listed in the Coupled Model Intercomparison Project phase 5 (CMIP5), has been typically run with resolutions of 60 km and 20 km. Ensembles of MRI-AGCM3.2 consist of members with multiple cumulus convection schemes and different patterns of future sea surface temperature, and are utilized together with their downscaled data; however, the limited size of the high-resolution ensemble may lead to undesirable biases and uncertainty in future climate projections that will limit its appropriateness and effectiveness for studies on climate change and impact assessments. In this study, to develop a comprehensive understanding of the regional precipitation simulated with MRI-AGCM3.2, we investigate how well MRI-AGCM3.2 simulates the present-day regional precipitation around the globe and compare the uncertainty in future precipitation changes and the change projection itself between MRI-AGCM3.2 and the CMIP5 multiple atmosphere–ocean coupled GCM (AOGCM) ensemble. MRI-AGCM3.2 reduces the bias of the regional mean precipitation obtained with the high-performing CMIP5 models, with a reduction of approximately 20% in the bias over the Tibetan Plateau through East Asia and Australia. When 26 global land regions are considered, MRI-AGCM3.2 simulates the spatial pattern and the regional mean realistically in more regions than the individual CMIP5 models. As for the future projections, in 20 of the 26 regions, the sign of annual precipitation change is identical between the 50th percentiles of the MRI-AGCM3.2 ensemble and the CMIP5 multi-model ensemble. In the other six regions around the tropical South Pacific, the differences in modeling with and without atmosphere–ocean coupling may affect the projections. The uncertainty in future changes in annual precipitation from MRI-AGCM3.2 partially overlaps the maximum–minimum uncertainty range from the full ensemble of the CMIP5 models in all regions. Moreover, on average over individual regions, the projections from MRI-AGCM3.2 spread over roughly 0.8 of the uncertainty range from the high-performing CMIP5 models compared to 0.4 of the range of the full ensemble.

scholarly journals Climate SPHINX: evaluating the impact of resolution and stochastic physics parameterisations in the EC-Earth global climate model

2017 ◽  
Vol 10 (3) ◽  
pp. 1383-1402 ◽  
Author(s):  
Paolo Davini ◽  
Jost von Hardenberg ◽  
Susanna Corti ◽  
Hannah M. Christensen ◽  
Stephan Juricke ◽  
...  
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Climate Model ◽  
Global Climate ◽  
Rainfall Variability ◽  
Global Climate Model ◽  
Small Scale ◽  
Low Resolution ◽  
The Impact ◽  
Stochastic Physics

Abstract. The Climate SPHINX (Stochastic Physics HIgh resolutioN eXperiments) project is a comprehensive set of ensemble simulations aimed at evaluating the sensitivity of present and future climate to model resolution and stochastic parameterisation. The EC-Earth Earth system model is used to explore the impact of stochastic physics in a large ensemble of 30-year climate integrations at five different atmospheric horizontal resolutions (from 125 up to 16 km). The project includes more than 120 simulations in both a historical scenario (1979–2008) and a climate change projection (2039–2068), together with coupled transient runs (1850–2100). A total of 20.4 million core hours have been used, made available from a single year grant from PRACE (the Partnership for Advanced Computing in Europe), and close to 1.5 PB of output data have been produced on SuperMUC IBM Petascale System at the Leibniz Supercomputing Centre (LRZ) in Garching, Germany. About 140 TB of post-processed data are stored on the CINECA supercomputing centre archives and are freely accessible to the community thanks to an EUDAT data pilot project. This paper presents the technical and scientific set-up of the experiments, including the details on the forcing used for the simulations performed, defining the SPHINX v1.0 protocol. In addition, an overview of preliminary results is given. An improvement in the simulation of Euro-Atlantic atmospheric blocking following resolution increase is observed. It is also shown that including stochastic parameterisation in the low-resolution runs helps to improve some aspects of the tropical climate – specifically the Madden–Julian Oscillation and the tropical rainfall variability. These findings show the importance of representing the impact of small-scale processes on the large-scale climate variability either explicitly (with high-resolution simulations) or stochastically (in low-resolution simulations).

scholarly journals Projected Changes in South Asian Monsoon Low Pressure Systems

2020 ◽  
Vol 33 (17) ◽  
pp. 7275-7287 ◽  
Author(s):  
Wenhao Dong ◽  
Yi Ming ◽  
V. Ramaswamy
Keyword(s):  
South Asian ◽  
Large Scale ◽  
Climate Model ◽  
Asian Summer Monsoon ◽  
Central India ◽  
Low Pressure ◽  
Geophysical Fluid Dynamics Laboratory ◽  
South Asian Summer Monsoon ◽  
Projected Changes ◽  
Low Pressure Systems

AbstractMonsoon low pressure systems (MLPSs) are among the most important synoptic-scale disturbances of the South Asian summer monsoon. Potential changes in their characteristics in a warmer climate would have broad societal impacts. Yet, the findings from a few existing studies are inconclusive. We use the Geophysical Fluid Dynamics Laboratory (GFDL) coupled climate model CM4.0 to examine the projected changes in the simulated MLPS activity under a future emission scenario. It is shown that CM4.0 can skillfully simulate the number, genesis location, intensity, and lifetime of MLPSs. Global warming gives rise to a significant decrease in MLPS activity. An analysis of several large-scale environmental variables, both dynamic and thermodynamic, suggests that the decrease in MLPS activity can be attributed mainly to a reduction in low-level relative vorticity over the core genesis region. The decreased vorticity is consistent with weaker large-scale ascent, which leads to less vorticity production through the stretching term in the vorticity equation. Assuming a fixed radius of influence, the projected reduction in MLPSs would significantly lower the associated precipitation over north-central India, despite an overall increase in mean precipitation.

Response of Tropical Cyclone Potential Intensity to a Global Warming Scenario in the IPCC AR4 CGCMs

2010 ◽  
Vol 23 (6) ◽  
pp. 1354-1373 ◽  
Author(s):  
Jinhua Yu ◽  
Yuqing Wang ◽  
Kevin Hamilton
Keyword(s):  
Global Warming ◽  
Tropical Cyclone ◽  
Large Scale ◽  
Linear Trend ◽  
Relative Effect ◽  
Vertical Shear ◽  
Model Parameters ◽  
Climate Projections ◽  
South Indian ◽  
Projected Changes

Abstract This paper reports on an analysis of the tropical cyclone (TC) potential intensity (PI) and its control parameters in transient global warming simulations. Specifically, the TC PI is calculated for phase 3 of the Coupled Model Intercomparison Project (CMIP3) integrations during the first 70 yr of a transient run forced by a 1% yr−1 CO2 increase. The linear trend over the period is used to project a 70-yr change in relevant model parameters. The results for a 15-model ensemble-mean climate projection show that the thermodynamic potential intensity (THPI) increases on average by 1.0% to ∼3.1% over various TC basins, which is mainly attributed to changes in the disequilibrium in enthalpy between the ocean and atmosphere in the transient response to increasing CO2 concentrations. This modest projected increase in THPI is consistent with that found in other recent studies. In this paper the effects of evolving large-scale dynamical factors on the projected TC PI are also quantified, using an empirical formation that takes into account the effects of vertical shear and translational speed based on a statistical analysis of present-day observations. Including the dynamical efficiency in the formulation of PI leads to larger projected changes in PI relative to that obtained using just THPI in some basins and smaller projected changes in others. The inclusion of the dynamical efficiency has the largest relative effect in the main development region (MDR) of the North Atlantic, where it leads to a 50% reduction in the projected PI change. Results are also presented for the basin-averaged changes in PI for the climate projections from each of the 15 individual models. There is considerable variation among the results for individual model projections, and for some models the projected increase in PI in the eastern Pacific and south Indian Ocean regions exceeds 10%.

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