Abraham, Subil, Ryan Prout, Thomas E Robinson, Chris Blanton, and Matthew Davis, May 2024: Evaluating integration and performance of containerized climate applications on a Hewlett Packard Enterprise Cray system. Concurrency and Computation: Practice and Experience, DOI:10.1002/cpe.7966. Abstract
Containers have taken over large swaths of cloud computing as the most convenient way of packaging and deploying applications. The features that containers offer for packaging and deploying applications translate to high performance computing (HPC) as well. At The National Oceanic and Atmospheric Administration, containers provide an easy way to build and distribute complex HPC applications, allowing faster collaboration, portability, and experiment computer environment reproducibility amongst the scientific community. The challenge arises when applications rely on message passing interface (MPI). This necessitates investigation into how to properly run these applications with their own unique requirements and produce performance on par with native runs. We investigate the MPI performance for benchmarks and containerized climate models for various containers covering selection of compiler and MPI library combinations from the Cray provided programming environments on the Cray XC supercomputer GAEA. Performance from the benchmarks and the climate models shows that for the most part containerized applications perform on par with the natively built applications when the system optimized Cray MPICH libraries are bound into the container, and the hybrid model containers have poor performance in comparison. We also describe several challenges and our solutions in running these containers, particularly challenges with heterogeneous jobs for the containerized model runs.
Worthen, Denise, Jun Wang, Raffaele Montuoro, Dom Heinzeller, Bin Li, G Theurich, Ufuk Turuncoglu, Dan Rosen, Dusan Jovic, Brian Curtis, Rahul Mahajan, Hang Lei, Alexander Richert, Arun Chawla, Jiande Wang, Jessica Meixner, Ali Abdolali, Matthew Masarik, Li Pan, Michael Barlage, Bin Liu, M Vertenstein, Tony Craig, Rusty Benson, and Thomas E Robinson, et al., June 2024: Coupling Infrastructure Capability in UFS Weather Model, College Park, MD: NOAA Technical Memorandum NWS NCEP, 519, DOI:10.25923/dvv2-3g03 115pp. Abstract
The Unified Forecast System (UFS) is an end-to-end forecast system for the next generation of the National Centers for Environmental Prediction (NCEP) production suite. The UFS weather-model (UWM) comprises the model component of the UFS. It consists of atmosphere, which currently includes the Finite Volume Cubed Sphere (FV3) dynamical core and the Common Community Physics Package, CCPP; ocean, sea ice, wave, land, aerosol, chemistry, and data model components with a central mediator component to couple the components together. The coupling strategy among the components uses the common Earth System Prediction Suite (ESPS) architecture, an Earth System Modeling Framework (ESMF) and National Unified Operational Prediction Capability (NUOPC) based coupling infrastructure framework. The NUOPC interfaces, also called caps, allow each model component to be an independent ESMF grid component. The coupling communication uses either generic UOPC
connectors or the NUOPC compliant Community Mediator for Earth Prediction Systems (CMEPS). This technical note provides details on the coupling capability available in the latest UWM. The model component NUOPC caps and component coupling strategies are documented. The coupled configurations, computational performance, and features that improve the computation performance are also illustrated.
We performed a series of aquaplanet simulations at the horizontal resolution from 50 to 6 km with identical parameterization settings using the Geophysical Fluid Dynamics Laboratory's Atmosphere Model version 4 implemented with the two-moment Morrison-Gettelman cloud microphysics with prognostic precipitation (GFDL AM4-MG2). At the finer resolution, the global mean resolved-scale precipitation increases and that from cumulus parameterization decreases. The model also simulates less/thinner clouds over the low latitudes and more/thicker clouds over the high latitudes as the resolution increases. The precipitation over the deep tropics is investigated in detail. We find little resolution sensitivity in the daily mean precipitation extremes. Changes of the equatorial resolved precipitation with resolution cannot be fully explained by the resolution dependence in the vertical velocity amplitude. We report a robust sensitivity in the convective organization over the deep tropics to the model resolution. In simulations of finer resolution, the localized convection is suppressed, and the organized convective system associated with large-scale circulations becomes more prominent.
Silvers, Levi G., and Thomas E Robinson, February 2021: Clouds and radiation in a mock-Walker circulation. Journal of Advances in Modeling Earth Systems, 13(2), DOI:10.1029/2020MS002196. Abstract
The Walker circulation connects the regions with deep atmospheric convection in the western tropical Pacific to the shallow-convection, tropospheric subsidence, and stratocumulus cloud decks of the eastern Pacific. The purpose of this study is to better understand the multi-scale interactions between the Walker circulation, cloud systems, and interactive radiation. To do this we simulate a mock-Walker Circulation with a full-physics general circulation model using idealized boundary conditions. Our experiments use a doubly-periodic domain with grid-spacing of 1, 2, 25, and 100 km. We thus span the range from General Circulation Models (GCMs) to Cloud-system Resolving Models (CRMs). Our model is derived from the Geophysical Fluid Dynamics Laboratory atmospheric GCM (AM4.0). We find substantial differences in the mock-Walker circulation simulated by our GCM-like and CRM-like experiments. The CRM-like experiments have more upper level clouds, stronger overturning circulations, and less precipitation. The GCM-like experiments have a low-level cloud fraction that is up to 20% larger. These differences leads to opposite atmospheric responses to changes in the longwave cloud radiative effect (LWCRE). Active LWCRE leads to increased precipitation for our GCMs, but decreased precipitation for our CRMs. The LWCRE leads to a narrower rising branch of the circulation and substantially increases the fraction of precipitation from the large-scale cloud parameterization. This work demonstrates that a mock-Walker circulation is a useful generalization of radiative convective equilibrium that includes a large-scale circulation.
We describe the baseline coupled model configuration and simulation characteristics of GFDL's Earth System Model Version 4.1 (ESM4.1), which builds on component and coupled model developments at GFDL over 2013–2018 for coupled carbon‐chemistry‐climate simulation contributing to the sixth phase of the Coupled Model Intercomparison Project. In contrast with GFDL's CM4.0 development effort that focuses on ocean resolution for physical climate, ESM4.1 focuses on comprehensiveness of Earth system interactions. ESM4.1 features doubled horizontal resolution of both atmosphere (2° to 1°) and ocean (1° to 0.5°) relative to GFDL's previous‐generation coupled ESM2‐carbon and CM3‐chemistry models. ESM4.1 brings together key representational advances in CM4.0 dynamics and physics along with those in aerosols and their precursor emissions, land ecosystem vegetation and canopy competition, and multiday fire; ocean ecological and biogeochemical interactions, comprehensive land‐atmosphere‐ocean cycling of CO2, dust and iron, and interactive ocean‐atmosphere nitrogen cycling are described in detail across this volume of JAMES and presented here in terms of the overall coupling and resulting fidelity. ESM4.1 provides much improved fidelity in CO2 and chemistry over ESM2 and CM3, captures most of CM4.0's baseline simulations characteristics, and notably improves on CM4.0 in (1) Southern Ocean mode and intermediate water ventilation, (2) Southern Ocean aerosols, and (3) reduced spurious ocean heat uptake. ESM4.1 has reduced transient and equilibrium climate sensitivity compared to CM4.0. Fidelity concerns include (1) moderate degradation in sea surface temperature biases, (2) degradation in aerosols in some regions, and (3) strong centennial scale climate modulation by Southern Ocean convection.
We describe GFDL's CM4.0 physical climate model, with emphasis on those aspects that may be of particular importance to users of this model and its simulations. The model is built with the AM4.0/LM4.0 atmosphere/land model and OM4.0 ocean model. Topics include the rationale for key choices made in the model formulation, the stability as well as drift of the pre‐industrial control simulation, and comparison of key aspects of the historical simulations with observations from recent decades. Notable achievements include the relatively small biases in seasonal spatial patterns of top‐of‐atmosphere fluxes, surface temperature, and precipitation; reduced double Intertropical Convergence Zone bias; dramatically improved representation of ocean boundary currents; a high quality simulation of climatological Arctic sea ice extent and its recent decline; and excellent simulation of the El Niño‐Southern Oscillation spectrum and structure. Areas of concern include inadequate deep convection in the Nordic Seas; an inaccurate Antarctic sea ice simulation; precipitation and wind composites still affected by the equatorial cold tongue bias; muted variability in the Atlantic Meridional Overturning Circulation; strong 100 year quasi‐periodicity in Southern Ocean ventilation; and a lack of historical warming before 1990 and too rapid warming thereafter due to high climate sensitivity and strong aerosol forcing, in contrast to the observational record. Overall, CM4.0 scores very well in its fidelity against observations compared to the Coupled Model Intercomparison Project Phase 5 generation in terms of both mean state and modes of variability and should prove a valuable new addition for analysis across a broad array of applications.
A new method for modeling the lowest model level vertical motion is described and validated. Instead of smoothing terrain heights, the new method calculates the terrain gradient on a high-resolution grid and averages the gradient values around a gridpoint location. In essence, the method provides a way to achieve some of the impact of very steep terrain on the flow without the computational overhead associated with the very high grid resolution needed to fully resolve complex terrain. The more accurate depiction of the terrain gradient leads to an increase in orographic vertical motion and causes rainfall to occur more often over the windward-facing mountain slopes, consistent with observations. Model results are compared with rain gauge data during the month of January 2016 as well as radar data from a case study on 9 March 2012. When implemented in the Weather Research and Forecasting (WRF) Model over the island of Oahu and compared with the current WRF method, the model precipitation forecast skill is improved. The new method produces more precipitation over the island during January 2016, which is closer to the observed value. On 9 March 2012, the new method clearly focuses the precipitation over the Ko‘olau Mountains, reducing the number of false alarm forecasts by nearly one-half. Although the changes to model precipitation skill were small, they were generally positive.
In this two-part paper, a description is provided of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). This version, with roughly 100km horizontal resolution and 33 levels in the vertical, contains an aerosol model that generates aerosol fields from emissions and a “light” chemistry mechanism designed to support the aerosol model but with prescribed ozone. In Part I, the quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode – with prescribed sea surface temperatures (SSTs) and sea ice distribution – is described and compared with previous GFDL models and with the CMIP5 archive of AMIP simulations. The model's Cess sensitivity (response in the top-of-atmosphere radiative flux to uniform warming of SSTs) and effective radiative forcing are also presented. In Part II, the model formulation is described more fully and key sensitivities to aspects of the model formulation are discussed, along with the approach to model tuning.
In Part II of this two-part paper, documentation is provided of key aspects of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode has been provided in Part I. Part II provides documentation of key components and some sensitivities to choices of model formulation and values of parameters, highlighting the convection parameterization and orographic gravity wave drag. The approach taken to tune the model's clouds to observations is a particular focal point. Care is taken to describe the extent to which aerosol effective forcing and Cess sensitivity have been tuned through the model development process, both of which are relevant to the ability of the model to simulate the evolution of temperatures over the last century when coupled to an ocean model.
