Islet: interpolation semi-Lagrangian element-based transport

Bradley, Andrew M.; Bosler, Peter Andrew; Guba, Oksana

doi:10.5194/gmd-15-6285-2022

Cited by 13 publications

(8 citation statements)

References 33 publications

(34 reference statements)

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“…Because the model code was frozen before the Islet bases were finalized, the formulation of the n p = 4 stable basis set is slightly different than reported in Bradley et al. (2021), but this difference has essentially no impact. To achieve global mass conservation, shape preservation, and mass‐tracer consistency, Islet uses element‐local and global versions of the communication‐efficient density reconstructor (CEDR) described in Algorithm 3.1 of Bradley et al.…”

Section: Model Descriptionmentioning

confidence: 98%

“…The dynamical core's passive tracer transport method is a new interpolation semi‐Lagrangian (ISL) scheme called Islet (Bradley et al., 2021). A high‐order ISL method using the natural Gauss‐Lobatto‐Legendre element‐local interpolant is unstable; thus, Islet provides modified element‐local interpolation basis functions that obey a necessary condition for stability.…”

Section: Model Descriptionmentioning

confidence: 99%

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The DOE E3SM Model Version 2: Overview of the Physical Model and Initial Model Evaluation

Golaz

Roekel

Zheng

et al. 2022

J Adv Model Earth Syst

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This work documents version two of the Department of Energy's Energy Exascale Earth SystemModel (E3SM). E3SMv2 is a significant evolution from its predecessor E3SMv1, resulting in a model that is nearly twice as fast and with a simulated climate that is improved in many metrics. We describe the physical climate model in its lower horizontal resolution configuration consisting of 110 km atmosphere, 165 km land, 0.5° river routing model, and an ocean and sea ice with mesh spacing varying between 60 km in the mid-latitudes and 30 km at the equator and poles. The model performance is evaluated with Coupled Model Intercomparison Project Phase 6 Diagnosis, Evaluation, and Characterization of Klima simulations augmented with historical simulations as well as simulations to evaluate impacts of different forcing agents. The simulated climate has many realistic features of the climate system, with notable improvements in clouds and precipitation compared to E3SMv1. E3SMv1 suffered from an excessively high equilibrium climate sensitivity (ECS) of 5.3 K. In E3SMv2, ECS is reduced to 4.0 K which is now within the plausible range based on a recent World Climate Research Program assessment. However, a number of important biases remain including a weak Atlantic Meridional Overturning Circulation, deficiencies in the characteristics and spectral distribution of tropical atmospheric variability, and a significant underestimation of the observed warming in the second half of the historical period. An analysis of single-forcing simulations indicates that correcting the historical temperature bias would require a substantial reduction in the magnitude of the aerosol-related forcing.

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Section: Model Descriptionmentioning

confidence: 98%

Section: Model Descriptionmentioning

confidence: 99%

The DOE E3SM Model Version 2: Overview of the Physical Model and Initial Model Evaluation

Golaz

Roekel

Zheng

et al. 2022

J Adv Model Earth Syst

Self Cite

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show abstract

“…The average horizontal grid spacing is ∼110 km for the dynamic grid and ∼165 km for the physics grid. This new physics grid has little impact on modeled climate, but it is one of the two main factors (the other being a new semi‐Lagrangian passive tracer transport (Bradley et al., 2021)) that makes EAMv2 approximately two times faster than EAMv1.…”

Section: Models and Model Experimentsmentioning

confidence: 99%

Cloud Phase Simulation at High Latitudes in EAMv2: Evaluation Using CALIPSO Observations and Comparison With EAMv1

et al. 2022

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Clouds play an essential role in global climate through interactions with radiation and hydrological cycle. The extensive coverage and strong radiative effects make clouds an important modulator of the energy budget at the surface and top of the atmosphere. Cloud radiative effects are controlled by cloud optical depth and other optical properties that are closely related to cloud microphysical properties such as amount, size, shape, and thermodynamic phase of cloud hydrometeors (Curry & Ebert, 1992;Curry et al., 1996;Shupe & Intrieri, 2004). Cloud albedo is more sensitive to variations in cloud liquid water than cloud ice water. The shortwave radiative cooling effect due to liquid water usually dominates the net cloud radiative effect in mixed-phase clouds, highlighting the importance of cloud thermodynamic phase on cloud radiative forcing (Sun & Shine, 1994). In addition, differences in microphysical properties between liquid and ice are critical for global precipitation. Satellite observations have demonstrated that most of the Earth's precipitation originates from the ice phase and mixed-phase cloud processes, while warm rain mechanisms are more critical for precipitation over tropical and subtropical oceans (Field & Heymsfield, 2015;Heymsfield et al., 2020;Mülmenstädt et al., 2015). The distinct roles of cloud liquid and cloud ice on precipitation formation make cloud phase one of the key factors influencing the hydrological cycle in the Earth system. Moreover, the cloud liquid and ice microphysical properties in the present-day climate can also have a significant impact on the Arctic amplification (Middlemas et al., 2020) and future global climate change (Bjordal et al., 2020;Lohmann & Neubauer, 2018;Tsushima et al., 2006). For example, it has been found that the predicted Arctic amplification strength is highly sensitive to the ice particle size and number concentration of ice nucleating particles in the present-day environment (Tan & Storelvmo, 2019;Tan et al., 2022). Across the globe, if clouds in the present-day climate have a lower ice water amount, the phase transition from ice to liquid would be less significant in a future warmer climate, which would result in a weaker

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“…In the E3SMv2 atmosphere model (EAMv2), the dynamical core uses the High Order Method Modeling Environment (HOMME) package (Dennis et al, 2005(Dennis et al, , 2011Evans et al, 2013) on the spectral element grid (Taylor and Fournier, 2010). HOMME has been updated to use a potential temperature formulation of the equations with a more accurate pressure gradient (Taylor et al, 2020;Herrington et al, 2022) and a new interpolation semi-Lagrangian scheme (Islet) for passive tracer transport (Bradley et al, 2022). The physics operates on a separate finite volume grid (Hannah et al, 2021), which has 4/9 as many columns as the corresponding spectral element grid (see Table 1) and hence runs about 2x faster than it would on the spectral element grid.…”

Section: Model Descriptionmentioning

confidence: 99%

The Fully Coupled Regionally Refined Model of E3SM Version 2: Overview of the Atmosphere, Land, and River

Tang

Golaz

Roekel

et al. 2022

Preprint

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Abstract. This paper provides an overview of the United States (US) Department of Energy's (DOE's) Energy Exascale Earth System Model version 2 (E3SMv2) fully coupled Regionally Refined Model (RRM) and documents the overall atmosphere, land, and river results from the Coupled Model Intercomparison Project 6 (CMIP6) DECK (Diagnosis, Evaluation, and Characterization of Klima) and historical simulations – a first-of-kind set of climate production simulations using RRM. The North American (NA) RRM (NARRM) is developed as the high-resolution configuration of E3SMv2 with the primary goal of more explicitly addressing DOE's mission needs regarding impacts to the US energy sector facing Earth system changes. The NARRM features finer horizontal resolution grids centered over NA, consisting of 25→100 km atmosphere and land, 0.125° river routing model, and 14→60 km ocean and sea ice. By design, the computational cost of NARRM is ∼3x of the uniform low-resolution (LR) model at 100 km but only ∼10–20 % of a globally uniform high-resolution model at 25 km. A novel hybrid timestep strategy for the atmosphere is key for NARRM to achieve improved climate simulation fidelity within the high-resolution patch without sacrificing the overall global performance. The global climate, including climatology, time series, sensitivity, and feedback, is confirmed to be largely identical between NARRM and LR as quantified with typical climate metrics. Over the refined NA area, NARRM is generally superior to LR, including for precipitation and clouds over the contiguous US (CONUS), summertime marine stratocumulus clouds off the coast of California, liquid and ice phase clouds near the North polar region, extratropical cyclones, and spatial variability in land hydrological processes. The improvements over land are related to the better resolved topography in NARRM, whereas those over ocean are attributable to the improved air-sea interactions with finer grids for both atmosphere and ocean/sea ice. Some features appear insensitive to the resolution change analyzed here, for instance the diurnal propagation of organized mesoscale convective systems over CONUS, and the warm-season land-atmosphere coupling at the Southern Great Plains. In summary, our study presents a realistically efficient approach to leverage the RRM framework for a standard Earth system model release and high-resolution climate production simulations.

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Islet: interpolation semi-Lagrangian element-based transport

Cited by 13 publications

References 33 publications

The DOE E3SM Model Version 2: Overview of the Physical Model and Initial Model Evaluation

The DOE E3SM Model Version 2: Overview of the Physical Model and Initial Model Evaluation

Cloud Phase Simulation at High Latitudes in EAMv2: Evaluation Using CALIPSO Observations and Comparison With EAMv1

The Fully Coupled Regionally Refined Model of E3SM Version 2: Overview of the Atmosphere, Land, and River

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