Specified dynamics scheme impacts on wave-mean flow dynamics, convection, and tracer transport in CESM2 (WACCM6)

Abstract. Specified dynamics schemes are ubiquitous modeling tools for isolating the roles of dynamics and transport on chemical weather and climate. They typically constrain the circulation of a chemistry–climate model to the circulation in a reanalysis product through linear relaxation. However, recent studies suggest that these schemes create a divergence in chemical climate and the meridional circulation between models and do not accurately reproduce trends in the circulation. In this study we perform a systematic assessment of the specified dynamics scheme in the Community Earth System Model version 2, Whole Atmosphere Community Climate Model version 6 (CESM2 (WACCM6)), which proactively nudges the circulation toward the reference meteorology. Specified dynamics experiments are performed over a wide range of nudging timescales and reference meteorology frequencies, with the model's circulation nudged to its own free-running output – a clean test of the specified dynamics scheme. Errors in the circulation scale robustly and inversely with meteorology frequency and have little dependence on the nudging timescale. However, the circulation strength and errors in tracers, tracer transport, and convective mass flux scale robustly and inversely with the nudging timescale. A 12 to 24 h nudging timescale at the highest possible reference meteorology frequency minimizes errors in tracers, clouds, and the circulation, even up to the practical limit of one reference meteorology update every time step. The residual circulation and eddy mixing integrate tracer errors and accumulate them at the end of their characteristic transport pathways, leading to elevated error in the upper troposphere and lower stratosphere and in the polar stratosphere. Even in the most ideal case, there are non-negligible errors in tracers introduced by the nudging scheme. Future development of more sophisticated nudging schemes may be necessary for further progress.

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Specified dynamics scheme impacts on wave-mean ﬂow dynamics, convection, and tracer transport in CESM2 (WACCM6)

10.5194/acp-2021-169 ◽

2021 ◽

Author(s):

Nicholas A. Davis ◽

Patrick Callaghan ◽

Isla R. Simpson ◽

Simone Tilmes

Keyword(s):

Climate Model ◽

Tracer Transport ◽

Residual Circulation ◽

Mean Flow ◽

Modeling Tools ◽

Transport Pathways ◽

Systematic Assessment ◽

Model Version ◽

Wide Range ◽

Chemical Climate

Abstract. Specified dynamics schemes are ubiquitous modeling tools for isolating the role of dynamics and transport on chemical weather and climate. They typically constrain the circulation of a chemistry-climate model to the circulation in a reanalysis product through linear relaxation. However, recent studies suggest that these schemes create a divergence in chemical climate and the meridional circulation between models and do not accurately reproduce trends in the circulation. In this study we perform a systematic assessment of the specified dynamics scheme in the Community Earth System Model version 2, Whole Atmosphere Community Climate Model version 6 (CESM2 (WACCM6)), which proactively nudges the circulation toward the reference meteorology. Specified dynamics experiments are performed over a wide range of nudging timescales and reference meteorology frequencies, with the model's circulation nudged to its own free-running output - a clean test of the specified dynamics scheme. Errors in the circulation scale robustly and inversely with meteorology frequency, and have little dependence on nudging timescale. However, the circulation strength and errors in tracers, tracer transport, and convective mass flux scale robustly and inversely with nudging timescale. A 12 to 24 hour nudging timescale at the highest possible reference meteorology frequency minimizes errors in tracers, clouds, and the circulation, even up to the practical limit of one reference meteorology update every timestep. The residual circulation and eddy mixing integrate tracer errors and accumulate them at the end of their characteristic transport pathways, leading to elevated error in the upper troposphere/lower stratosphere and in the polar stratosphere. Even in the most ideal case, there are non-negligible errors in tracers introduced by the nudging scheme. Future development of more sophisticated nudging schemes may be necessary for further progress.

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Incorporation of the C-GOLDSTEIN efficient climate model into the GENIE framework: "eb_go_gs" configurations of GENIE

Geoscientific Model Development ◽

10.5194/gmd-4-957-2011 ◽

2011 ◽

Vol 4 (4) ◽

pp. 957-992 ◽

Cited By ~ 28

Author(s):

R. Marsh ◽

S. A. Müller ◽

A. Yool ◽

N. R. Edwards

Keyword(s):

Sea Ice ◽

Climate Model ◽

Horizontal Resolution ◽

Wind Forcing ◽

The Arctic ◽

System Modelling ◽

State Variables ◽

Time Step ◽

Transport Pathways ◽

Ocean Atmosphere

Abstract. A computationally efficient, intermediate complexity ocean-atmosphere-sea ice model (C-GOLDSTEIN) has been incorporated into the Grid ENabled Integrated Earth system modelling (GENIE) framework. This involved decoupling of the three component modules that were re-coupled in a modular way, to allow replacement with alternatives and coupling of further components within the framework. The climate model described here (referred to as "eb_go_gs" for short) is the most basic version of GENIE in which atmosphere, ocean and sea ice all play an active role. Among improvements on the original C-GOLDSTEIN model, latitudinal grid resolution is generalized to allow a wider range of surface grids to be used. The ocean, atmosphere and sea-ice components of the "eb_go_gs" configuration of GENIE are individually described, along with details of their coupling. The setup and results from simulations using four different meshes are presented. The four alternative meshes comprise the widely-used 36 × 36 equal-area-partitioning of the Earth surface with 16 depth layers in the ocean, a version in which horizontal and vertical resolution are doubled, a setup matching the horizontal resolution of the dynamic atmospheric component available in the GENIE framework, and a setup with enhanced resolution in high-latitude areas. Results are presented for a spin-up experiment with a baseline parameter set and wind forcing typically used for current studies in which "eb_go_gs" is coupled with the ocean biogeochemistry module of GENIE, as well as for an experiment with a modified parameter set, revised wind forcing, and additional cross-basin transport pathways (Indonesian and Bering Strait throughflows). The latter experiment is repeated with the four mesh variants, with common parameter settings throughout, except for time-step length. Selected state variables and diagnostics are compared in two regards: (i) between simulations at lowest resolution that are obtained with the baseline and modified configurations, predominantly in order to evaluate the revision of the wind forcing, the modification of some key parameters, and the effect of additional transport pathways across the Arctic Ocean and the Indonesian Archipelago; (ii) between simulations with the four meshes, in order to explore various effects of mesh choice.

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Parameterizing gravity waves in the DYNAMICO-Saturn Global Climate Model to understand Saturn's equatorial oscillation

10.5194/epsc2020-601 ◽

2020 ◽

Author(s):

Deborah Bardet ◽

Aymeric Spiga ◽

Sandrine Guerlet ◽

Ehouarn Millour ◽

François Lott

Keyword(s):

Gravity Waves ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Life Cycles ◽

Small Scale ◽

Mean Flow ◽

Time Step ◽

Maximum Value ◽

The Mean

To address questions about the driving mechanisms of Saturn's equatorial oscillation, our team at the Laboratoire de M&#233;t&#233;orologie Dynamique built the DYNAMICO-Saturn Global Climate Model to study tropospheric dynamics, tropospheric waves activity (Spiga et al. 2020) and equatorial stratospheric dynamics (Bardet et al. 2020) of Saturn. Previous studies (Guerlet et al. 2014, Spiga et al. 2020, Cabanes et al. 2020) have shown that our model produces consistent thermal structure and seasonal variability compared to Cassini CIRS measurements, mid-latitude eddy-driven tropospheric eastward and westward jets commensurate to those observed and following the zonostrophic regime, and planetary-scale waves such as Rossby-gravity (Yanai), Rossby and Kelvin waves in the tropical channel. Extending the model top toward the upper stratosphere allowed our model to produce an almost semi-annual equatorial oscillation with opposite eastward and westward phases. Associated temperature anomalies have a similar behavior than the Cassini/CIRS observations, but the amplitude of the temperature oscillation is twice smaller than the observed one. The absence of sub-grid-scale waves in the model produces an imbalance in eastward- and westward-wave forcing on the mean flow and could be an explanation to the irregularity in both the oscillating period and the downward rate propagation of the resolved Saturn equatorial oscillation. To explore the impact of those small-scale waves on the spontaneous equatorial oscillation emerging in the DYNAMICO-Saturn GCM (Bardet et al. 2020), we add a sub-grid-scale non-orographic gravity waves drag parameterization in our model. This parameterization is directly adapted from the stochastic terrestrial model of Lott et al. (2012). This formalism represents a broadband gravity wave spectrum, using the superposition of a large statistical set of monochromatic waves. As the time scale of the life cycles of gravity waves is much longer than the time step of our GCM, our parametrization can launch a few waves whose characteristics are randomly chosen at each time step. This stochastic gravity waves drag parameterization is applied in DYNAMICO-Saturn on all points of the horizontal grid. A key parameter used in the non-orographic gravity waves drag parameterization is the maximum value of the Eliassen-Palm flux. The Eliassen Palm flux represents the momentum carried by waves that could be transferred to the mean flow. This value has never been measured in Saturn's atmosphere and it represents an important degree of freedom in the parameterization of gravity waves. We performed several test simulations, lasting two Saturn years whose initial state is derived from Bardet et al (2020), with an horizontal resolution of 1/2&#176; in longitude/latitude and a vertical resolution ranging between 3 bar to 1 &#956;bar. For these test simulations, the maximum value of the Eliassen-Palm fulx is set to 10-6, 10-5, 10-4 and 10-3 kg m-1 s-2.&#160; Preliminary results show that the appropriate value of our main parameter is between 10-5 and 10-4 kg m-1 s-2. Eliassen-Palm flux value of 10-3 kg m-1 s-2 demonstrates a too large impact: the equatorial oscillation is entirely vanished is this configuration. The simulation using the value of 10-6 kg m-1 s-2 is equivalent to the control simulation without the gravity waves drag parameterization. &#160; The next step is to test other parameters, as phase velocity of the gravity waves, horizontal wavenumber, to understand how gravity waves impact the equatorial oscillation.

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Significant improvement of cloud representation in the global climate model MRI-ESM2

Geoscientific Model Development ◽

10.5194/gmd-12-2875-2019 ◽

2019 ◽

Vol 12 (7) ◽

pp. 2875-2897 ◽

Cited By ~ 8

Author(s):

Hideaki Kawai ◽

Seiji Yukimoto ◽

Tsuyoshi Koshiro ◽

Naga Oshima ◽

Taichu Tanaka ◽

...

Keyword(s):

Southern Ocean ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Cloud Microphysics ◽

Time Step ◽

Model Version ◽

Meteorological Research Institute ◽

Cloud Ice ◽

Research Institute

Abstract. The development of the climate model MRI-ESM2 (Meteorological Research Institute Earth System Model version 2), which is planned for use in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) simulations, involved significant improvements to the representation of clouds from the previous version MRI-CGCM3 (Meteorological Research Institute Coupled Global Climate Model version 3), which was used in the CMIP5 simulations. In particular, the serious lack of reflection of solar radiation over the Southern Ocean in MRI-CGCM3 was drastically improved in MRI-ESM2. The score of the spatial pattern of radiative fluxes at the top of the atmosphere for MRI-ESM2 is better than for any CMIP5 model. In this paper, we set out comprehensively the various modifications related to clouds that contribute to the improved cloud representation and the main impacts on the climate of each modification. The modifications cover various schemes and processes including the cloud scheme, turbulence scheme, cloud microphysics processes, interaction between cloud and convection schemes, resolution issues, cloud radiation processes, interaction with the aerosol model, and numerics. In addition, the new stratocumulus parameterization, which contributes considerably to increased low-cloud cover and reduced radiation bias over the Southern Ocean, and the improved cloud ice fall scheme, which alleviates the time-step dependency of cloud ice content, are described in detail.

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The role of the winter residual circulation in the summer mesopause regions in WACCM

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-4217-2018 ◽

2018 ◽

Vol 18 (6) ◽

pp. 4217-4228 ◽

Cited By ~ 1

Author(s):

Maartje Sanne Kuilman ◽

Bodil Karlsson

Keyword(s):

Planetary Wave ◽

Climate Model ◽

Zonal Flow ◽

Global Scale ◽

Wave Activity ◽

Latitudinal Gradients ◽

Residual Circulation ◽

Mean Flow ◽

Vertically Propagating

Abstract. High winter planetary wave activity warms the summer polar mesopause via a link between the two hemispheres. Complex wave–mean-flow interactions take place on a global scale, involving sharpening and weakening of the summer zonal flow. Changes in the wind shear occasionally generate flow instabilities. Additionally, an altering zonal wind modifies the breaking of vertically propagating gravity waves. A crucial component for changes in the summer zonal flow is the equatorial temperature, as it modifies latitudinal gradients. Since several mechanisms drive variability in the summer zonal flow, it can be hard to distinguish which one is dominant. In the mechanism coined interhemispheric coupling, the mesospheric zonal flow is suggested to be a key player for how the summer polar mesosphere responds to planetary wave activity in the winter hemisphere. We here use the Whole Atmosphere Community Climate Model (WACCM) to investigate the role of the summer stratosphere in shaping the conditions of the summer polar mesosphere. Using composite analyses, we show that in the absence of an anomalous summer mesospheric temperature gradient between the equator and the polar region, weak planetary wave forcing in the winter would lead to a warming of the summer mesosphere region instead of a cooling, and vice versa. This is opposing the temperature signal of the interhemispheric coupling that takes place in the mesosphere, in which a cold and calm winter stratosphere goes together with a cold summer mesopause. We hereby strengthen the evidence that the variability in the summer mesopause region is mainly driven by changes in the summer mesosphere rather than in the summer stratosphere.

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Multi-Iteration Approach to Studying Tracer Spreading Using Drifter Data

Journal of Physical Oceanography ◽

10.1175/jpo-d-16-0165.1 ◽

2017 ◽

Vol 47 (2) ◽

pp. 339-351 ◽

Cited By ~ 5

Author(s):

Irina I. Rypina ◽

David Fertitta ◽

Alison Macdonald ◽

Sachiko Yoshida ◽

Steven Jayne

Keyword(s):

North Atlantic ◽

North Atlantic Ocean ◽

Irish Sea ◽

Travel Times ◽

Tracer Transport ◽

Mean Flow ◽

Transport Pathways ◽

The North ◽

Geographical Regions ◽

Eastern North Atlantic

AbstractA novel multi-iteration statistical method for studying tracer spreading using drifter data is introduced. The approach allows for the best use of the available drifter data by making use of a simple iterative procedure, which results in the statistically probable map showing the likelihood that a tracer released at some source location would visit different geographical regions, along with the associated arrival travel times. The technique is tested using real drifter data in the North Atlantic. Two examples are considered corresponding to sources in the western and eastern North Atlantic Ocean, that is, Massachusetts Bay–like and Irish Sea–like sources, respectively. In both examples, the method worked well in estimating the statistics of the tracer transport pathways and travel times throughout the entire North Atlantic. The role of eddies versus mean flow is quantified using the same technique, and eddies are shown to significantly broaden the spread of a tracer. The sensitivity of the results to the size of the source domain is investigated and causes for this sensitivity are discussed.

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Diagnosis of Zonal Mean Relative Humidity Changes in a Warmer Climate

Journal of Climate ◽

10.1175/2010jcli3488.1 ◽

2010 ◽

Vol 23 (17) ◽

pp. 4556-4569 ◽

Cited By ~ 40

Author(s):

Jonathon S. Wright ◽

Adam Sobel ◽

Joseph Galewsky

Keyword(s):

Relative Humidity ◽

Climate Model ◽

Transport Model ◽

Global Climate ◽

Global Climate Model ◽

Lower Troposphere ◽

Hadley Cell ◽

Tracer Transport ◽

Transport Pathways ◽

Extratropical Tropopause

Abstract The zonal mean relative humidity response to a doubling of CO2 in a climate model is examined using a global climate model and an offline tracer transport model. Offline tracer transport model simulations are driven by the output from two configurations of the climate model, one with 1979 concentrations of atmospheric greenhouse gases and one with doubled CO2. A set of last saturation tracers is applied within the tracer transport model to diagnose the dynamics responsible for features in the water vapor field. Two different methods are used to differentiate the effects of circulation and transport shifts from spatially inhomogeneous temperature changes. The first of these uses the tracer transport model and is achieved by decoupling the input temperature and circulation fields; the second uses the reconstruction of humidity from the last saturation tracers and is achieved by decoupling the tracer concentrations from their saturation specific humidities. The responses of the tropical and subtropical relative humidities are found to be largely dependent on circulation and transport changes, particularly a poleward expansion of the Hadley cell, a deepening of the height of convective detrainment, a poleward shift of the extratropical jets, and an increase in the height of the tropopause. The last saturation tracers are used to illustrate the influence of changes in transport pathways within the GCM on the zonal mean relative humidity, particularly in the tropical upper troposphere and subtropical dry zones. Relative humidity changes near the extratropical tropopause and in the lower troposphere are largely dependent on changes in the distribution and gradients of temperature. Increases in relative humidity near the extratropical tropopause in both hemispheres are coincident with increases in the occurrence of local saturation and high cloud cover.

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Structure Guided Molecular Docking Assisted Alignment Dependent 3DQSAR Study on Steroidal Aromatase Inhibitors (SAIs) as Anti-breast Cancer Agents

Letters in Drug Design & Discovery ◽

10.2174/1570180815666181010101024 ◽

2019 ◽

Vol 16 (7) ◽

pp. 808-817 ◽

Cited By ~ 3

Author(s):

Laxmi Banjare ◽

Sant Kumar Verma ◽

Akhlesh Kumar Jain ◽

Suresh Thareja

Keyword(s):

Breast Cancer ◽

Molecular Docking ◽

Aromatase Inhibitors ◽

Direct Synthesis ◽

3D Qsar ◽

Chemotherapeutic Agents ◽

Modeling Tools ◽

Data Set ◽

Wide Range ◽

Steroidal Aromatase Inhibitors

Background: In spite of the availability of various treatment approaches including surgery, radiotherapy, and hormonal therapy, the steroidal aromatase inhibitors (SAIs) play a significant role as chemotherapeutic agents for the treatment of estrogen-dependent breast cancer with the benefit of reduced risk of recurrence. However, due to greater toxicity and side effects associated with currently available anti-breast cancer agents, there is emergent requirement to develop target-specific AIs with safer anti-breast cancer profile. Methods: It is challenging task to design target-specific and less toxic SAIs, though the molecular modeling tools viz. molecular docking simulations and QSAR have been continuing for more than two decades for the fast and efficient designing of novel, selective, potent and safe molecules against various biological targets to fight the number of dreaded diseases/disorders. In order to design novel and selective SAIs, structure guided molecular docking assisted alignment dependent 3D-QSAR studies was performed on a data set comprises of 22 molecules bearing steroidal scaffold with wide range of aromatase inhibitory activity. Results: 3D-QSAR model developed using molecular weighted (MW) extent alignment approach showed good statistical quality and predictive ability when compared to model developed using moments of inertia (MI) alignment approach. Conclusion: The explored binding interactions and generated pharmacophoric features (steric and electrostatic) of steroidal molecules could be exploited for further design, direct synthesis and development of new potential safer SAIs, that can be effective to reduce the mortality and morbidity associated with breast cancer.

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Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models

npj Climate and Atmospheric Science ◽

10.1038/s41612-020-00159-2 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Zhili Wang ◽

Lei Lin ◽

Yangyang Xu ◽

Huizheng Che ◽

Xiaoye Zhang ◽

...

Keyword(s):

Climate Change ◽

Radiative Forcing ◽

Impact Analysis ◽

Climate Model ◽

Regional Climate ◽

Eastern China ◽

Coupled Model ◽

Regional Climate Change ◽

Anthropogenic Aerosol ◽

Wide Range

AbstractAnthropogenic aerosol (AA) forcing has been shown as a critical driver of climate change over Asia since the mid-20th century. Here we show that almost all Coupled Model Intercomparison Project Phase 6 (CMIP6) models fail to capture the observed dipole pattern of aerosol optical depth (AOD) trends over Asia during 2006–2014, last decade of CMIP6 historical simulation, due to an opposite trend over eastern China compared with observations. The incorrect AOD trend over China is attributed to problematic AA emissions adopted by CMIP6. There are obvious differences in simulated regional aerosol radiative forcing and temperature responses over Asia when using two different emissions inventories (one adopted by CMIP6; the other from Peking university, a more trustworthy inventory) to driving a global aerosol-climate model separately. We further show that some widely adopted CMIP6 pathways (after 2015) also significantly underestimate the more recent decline in AA emissions over China. These flaws may bring about errors to the CMIP6-based regional climate attribution over Asia for the last two decades and projection for the next few decades, previously anticipated to inform a wide range of impact analysis.

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Transferability Intercomparison: An Opportunity for New Insight on the Global Water Cycle and Energy Budget

Bulletin of the American Meteorological Society ◽

10.1175/bams-88-3-375 ◽

2007 ◽

Vol 88 (3) ◽

pp. 375-384 ◽

Cited By ~ 39

Author(s):

E. S. Takle ◽

J. Roads ◽

B. Rockel ◽

W. J. Gutowski ◽

R. W. Arritt ◽

...

Keyword(s):

Energy Budget ◽

Climate Models ◽

Climate Model ◽

Water Cycle ◽

Regional Climate ◽

Climate Conditions ◽

Continental Scale ◽

Global Water Cycle ◽

Wide Range ◽

Global Water

A new approach, called transferability intercomparisons, is described for advancing both understanding and modeling of the global water cycle and energy budget. Under this approach, individual regional climate models perform simulations with all modeling parameters and parameterizations held constant over a specific period on several prescribed domains representing different climatic regions. The transferability framework goes beyond previous regional climate model intercomparisons to provide a global method for testing and improving model parameterizations by constraining the simulations within analyzed boundaries for several domains. Transferability intercomparisons expose the limits of our current regional modeling capacity by examining model accuracy on a wide range of climate conditions and realizations. Intercomparison of these individual model experiments provides a means for evaluating strengths and weaknesses of models outside their “home domains” (domain of development and testing). Reference sites that are conducting coordinated measurements under the continental-scale experiments under the Global Energy and Water Cycle Experiment (GEWEX) Hydrometeorology Panel provide data for evaluation of model abilities to simulate specific features of the water and energy cycles. A systematic intercomparison across models and domains more clearly exposes collective biases in the modeling process. By isolating particular regions and processes, regional model transferability intercomparisons can more effectively explore the spatial and temporal heterogeneity of predictability. A general improvement of model ability to simulate diverse climates will provide more confidence that models used for future climate scenarios might be able to simulate conditions on a particular domain that are beyond the range of previously observed climates.

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