Reduced tropical cyclone densities and ocean effects due to anthropogenic greenhouse warming

Tropical cyclones (TCs) are extreme storms that form over warm tropical oceans. Along their tracks, TCs mix up cold water, which can further affect their intensity. Because of the adoption of lower-resolution ocean models, previous modeling studies on the TC response to greenhouse warming underestimated such oceanic feedbacks. To address the robustness of TC projections in the presence of mesoscale air-sea interactions and complex coastal topography, we conduct greenhouse warming experiments using an ultrahigh-resolution Earth System Model. We find that a projected weakening of the rising branches of the summer Hadley cells suppresses future TC genesis and TC-generated ocean cooling. The forced response is similar to recent observational trends, indicating a possible emergence of the anthropogenic signal beyond natural variability levels. In the greenhouse warming simulations, landfalling TCs intensify, both in terms of wind speed and associated rainfall. Our modeling results provide relevant information for climate change adaptation efforts.

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Sea-state dependency of air-sea fluxes for high winds in ECMWF Earth System Model

10.5194/egusphere-egu2020-6074 ◽

2020 ◽

Author(s):

Jean Bidlot

Keyword(s):

Drag Coefficient ◽

Tropical Cyclones ◽

Coupled System ◽

Wave Model ◽

Earth System Model ◽

System Model ◽

Earth System ◽

Sea State ◽

Medium Range ◽

Fully Coupled

The global analyses and medium range forecasts from the European Centre for Medium range Weather Forecasts rely on a state-of-the-art Numerical Weather Prediction (NWP) system. To best represent the air-sea exchanges, it is tightly coupled to an ocean wave model.&#160; As part of ECMWF approach to Earth System Model, it is also coupled to a global ocean model for all its forecasting systems from the medium range up to the seasonal time scale.Because the feedback from and to the ocean can be significant, it is only in the fully coupled system that parameterisation for air-sea processes should be revisited. For instance, it is now accepted that the drag coefficient should generally attained maximum values for storm winds but should level or even decrease for very strong winds, namely in tropical cyclones or intense mid-latitude wind storms.A modification of the wind input source was tested, whereby the Charnock coefficient estimated by the wave model and therefore the drag coefficient sharply reduce for large winds (> 30 m/s). As a consequence, ECMWF tendency to under predict strong tropical cyclones was sharply alleviated, in better agreement with observational evidence. This change is now planned for operational implementation with the next model cycle (CY47R1, June 2020).Experimental evidences also point to a sea state/wind dependency of the heat and moisture fluxes.&#160; Following an extension of the wind wave generation theory, a sea state dependent parameterisation for the roughness length scales for heat and humidity has been tested. Again, a proper assessment of the different parameterisations warrants the fully coupled system. Experimentations so far indicate the benefit of such change. Ongoing work aims at future operational implementation.

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Weak Equatorial Superrotation During the Past 250 Million years

10.5194/egusphere-egu21-1503 ◽

2021 ◽

Author(s):

Jiawenjing Lan ◽

Jun Yang ◽

Yongyun Hu

Keyword(s):

Climatic Factors ◽

Co2 Concentration ◽

System Model ◽

Latent Heating ◽

Earth System ◽

Solar Constant ◽

Upper Troposphere ◽

The Past ◽

Hadley Cells ◽

The Waves

For modern Earth, the annual-mean equatorial atmosphere is flowing from east to west or called easterly winds. This is mainly due to the deceleration effect of the seasonal cross-equatorial flows of the Hadley cells, against the acceleration effect of equatorial Rossby and Kelvin waves excited from tropical convection and latent heating release. In this work, we examine the evolution of equatorial winds during the past 250 million years (Ma) using the global Earth system model CESM1.2.2. Three climatic factors different from the modern Earth, solar constant, atmospheric CO2 concentration, and land-sea configuration, are considered in the simulations. We find that the equatorial winds in the upper troposphere change the sign to westerly flows or called atmospheric superrotation in certain eras. The strength of the superrotation is comparable to the magnitude of the present easterly winds, several meters per second, not strong. This phenomenon occurs when the waves are relatively stronger and/or the Hadley cells are relatively weaker, which in turn are due to the changes in the three factors.

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Response of the Greenland and Antarctic Ice Sheets to Multi-Millennial Greenhouse Warming in the Earth System Model of Intermediate Complexity LOVECLIM

The Earth's Cryosphere and Sea Level Change - Space Sciences Series of ISSI ◽

10.1007/978-94-007-2063-3_7 ◽

2011 ◽

pp. 397-416 ◽

Cited By ~ 14

Author(s):

P. Huybrechts ◽

H. Goelzer ◽

I. Janssens ◽

E. Driesschaert ◽

T. Fichefet ◽

...

Keyword(s):

Ice Sheets ◽

Earth System Model ◽

System Model ◽

Greenhouse Warming ◽

Earth System ◽

Intermediate Complexity ◽

The Earth ◽

Antarctic Ice Sheets

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Altimeter-era emergence of the patterns of forced sea-level rise in climate models and implications for the future

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1813233115 ◽

2018 ◽

Vol 115 (51) ◽

pp. 12944-12949 ◽

Cited By ~ 15

Author(s):

John T. Fasullo ◽

R. Steven Nerem

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Climate Models ◽

Internal Variability ◽

Forced Response ◽

Earth System Model ◽

System Model ◽

Earth System ◽

Community Earth System Model

The satellite altimeter record has provided an unprecedented database for understanding sea-level rise and has recently reached a major milestone at 25 years in length. A challenge now exists in understanding its broader significance and its consequences for sea-level rise in the coming decades and beyond. A key question is whether the pattern of altimeter-era change is representative of longer-term trends driven by anthropogenic forcing. In this work, two multimember climate ensembles, the Community Earth System Model (CESM) and the Earth System Model Version 2M (ESM2M), are used to estimate patterns of forced change [also known as the forced response (FR)] and their magnitudes relative to internal variability. It is found that the spatial patterns of 1993–2018 trends in the ensembles correlate significantly with the contemporaneous FRs (0.55 ± 0.10 in the CESM and 0.61 ± 0.09 in the ESM2M) and the 1950–2100 FRs (0.43 ± 0.10 in the CESM and 0.51 ± 0.11 in the ESM2M). Unforced runs for each model show such correlations to be extremely unlikely to have arisen by chance, indicating an emergence of both the altimeter-era and long-term FRs and suggesting a similar emergence in nature. Projected patterns of the FR over the coming decades resemble those simulated during the altimeter era, suggesting a continuation of the forced pattern of change in nature in the coming decades. Notably, elevated rates of rise are projected to continue in regions that are susceptible to tropical cyclones, exacerbating associated impacts in a warming climate.

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Characterizing Tropical Cyclones in the Energy Exascale Earth System Model Version 1

Journal of Advances in Modeling Earth Systems ◽

10.1029/2019ms002024 ◽

2020 ◽

Vol 12 (8) ◽

Cited By ~ 1

Author(s):

Karthik Balaguru ◽

L. Ruby Leung ◽

Luke P. Van Roekel ◽

Jean‐Christophe Golaz ◽

Paul A. Ullrich ◽

...

Keyword(s):

Tropical Cyclones ◽

Earth System Model ◽

System Model ◽

Earth System ◽

Model Version

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Response of the Greenland and Antarctic Ice Sheets to Multi-Millennial Greenhouse Warming in the Earth System Model of Intermediate Complexity LOVECLIM

Surveys in Geophysics ◽

10.1007/s10712-011-9131-5 ◽

2011 ◽

Vol 32 (4-5) ◽

pp. 397-416 ◽

Cited By ~ 64

Author(s):

P. Huybrechts ◽

H. Goelzer ◽

I. Janssens ◽

E. Driesschaert ◽

T. Fichefet ◽

...

Keyword(s):

Ice Sheets ◽

Earth System Model ◽

System Model ◽

Greenhouse Warming ◽

Earth System ◽

Intermediate Complexity ◽

The Earth ◽

Antarctic Ice Sheets

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The forced response of the El Niño–Southern Oscillation-Indian monsoon teleconnection in ensembles of Earth System Models

10.5194/egusphere-egu2020-12061 ◽

2020 ◽

Author(s):

Tamas Bodai ◽

Gabor Drotos ◽

Matyas Herein ◽

Frank Lunkeit ◽

Valerio Lucarini

Keyword(s):

Southern Oscillation ◽

Correlation Coefficients ◽

Temporal Correlation ◽

Forced Response ◽

Earth System Model ◽

Turn Of The Century ◽

System Model ◽

Strong Increase ◽

Earth System ◽

Max Planck

We study the teleconnection between the El Ni&#241;o&#8211;Southern Oscillation (ENSO) and the Indian summer monsoon (IM) in large ensemble simulations, the Max Planck Institute Earth System Model (MPI-ESM) and the Community Earth System Model (CESM1). We characterize ENSO by the JJA Ni&#241;o 3 box-average SST and the IM by the JJAS average precipitation over India, and define their teleconnection in a changing climate as an ensemble-wise correlation. To test robustness, we also consider somewhat different variables that can characterize ENSO and the IM. We utilize ensembles converged to the system&#8217;s snapshot attractor for analyzing possible&#160;changes in the teleconnection. Our main finding is that the teleconnection strength is typically increasing on the long term in view of appropriately revised ensemble-wise indices. Indices involving a more western part of the Pacific reveal, furthermore, a short-term but rather strong increase in strength followed by some decrease at the turn of the century. Using the station-based SOI as opposed to area-based indices leads to the identification of somewhat more erratic trends, but the turn-of-the-century &#8220;bump&#8221; is well-detectable with it. All this is in contrast, if not in contradiction, with the discussion in the literature of a weakening teleconnection in the late 20th&#160;century. We show here that this discrepancy can be due to any of three reasons: ensemble-wise and temporal correlation coefficients used in the literature are different quantities; the temporal moving correlation has a high statistical variability but possibly also persistence; MPI-ESM does not represent the Earth system faithfully.

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