Simultaneous calculation of atmospheric processes is faster than calculating processes one at a time. This type of parallelism is beneficial or perhaps even necessary to provide good performance on modern supercomputers, which achieve faster performance through increased processor count rather than improved clock speed. The scalability of the E3SM Atmosphere Model (EAM) is limited by the fluid dynamics

This study presents the global climate model IPSL‐CM6A‐LR developed at IPSL to study natural climate variability and climate response to natural and anthropogenic forcings as part of the 6th phase of the Coupled Model Intercomparison Project (CMIP6). This article describes the different model components, their coupling, and the simulated climate in comparison to previous model versions. We focus here

One‐dimensional radiative transfer solvers are computationally much more efficient than full three‐dimensional radiative transfer solvers, but do not account for the horizontal propagation of radiation and thus produce unrealistic surface irradiance fields in models that resolve clouds. Here, we study the impact of using a 3D radiative transfer solver on the direct and diffuse solar irradiance beneath

The Earth’s climate is rapidly changing. Over the past centuries, aerosols, via their ability to absorb or scatter solar radiation and alter clouds, played an important role in counterbalancing some of the greenhouse gas (GHG) caused global warming. The multi‐century anthropogenic aerosol cooling effect prevented present‐day climate from reaching even higher surface air temperatures and subsequent

This study examines the role of soil moisture in modulating convective cold pool properties in an idealized modeling framework that uses a cloud‐resolving model coupled to an interactive land surface model. Five high‐resolution simulations of tropical continental convection are conducted in which the initial soil moisture is varied. The hundreds of cold pools forming within each simulation are identified

Previous work has established that warming is associated with an increase in dry static stability, a weakening of the tropical circulation, and a decrease in the convective mass flux. Using a set of idealized simulations with specified surface warming and super‐parameterized convection, we find support for these previous conclusions. We use an energy and mass balance framework to develop a simple diagnostic

Vegetation leaf phenology, often reflected by the dynamics in leaf area index (LAI), influences a variety of land surface processes. Robust models of vegetation phenology are pivot components in both land surface models and dynamic global vegetation models but remain challenging in terms of the model accuracy. This study develops a semi‐prognostic phenology model that is suitable for simulating time

Quantifying contributions of errors in model structure and parameters to biases in a land surface model (LSM) is critical for model improvement. This paper investigated the uncertainties in parameterizations and parameters in the Noah with multiparameterization (Noah‐MP) LSM with dynamic vegetation using eddy flux data. Firstly, we conducted full factorial experiments of eight land subprocesses, followed

No abstract is available for this article.

The characterization of uncertainties in geophysical quantities is an important task with widespread applications for time series prediction, numerical modeling, and data assimilation. In this context, machine learning is a powerful tool for estimating complex patterns and their evolution through time. Here, we utilize a supervised machine learning approach to dynamically predict the spatiotemporal

We describe and evaluate historical simulations which use the HadGEM3‐GC3.1 model, and which form part of the UK's contribution to the sixth Coupled Model Intercomparison Project, CMIP6. These simulations, run at two resolutions, respond to historically evolving forcings such as greenhouse gases, aerosols, solar irradiance, volcanic aerosols, land‐use, and ozone concentrations. We assess the response

Although fundamental to the planetary radiative balance, aerosol impacts are highly uncertain in climate simulations because of the uneven distribution of aerosol sources and the complex interactions with radiation and clouds that are difficult to represent in climate models. This study proposes that aquaplanet configurations represent an idealized framework to investigate aerosol effects. As a simple

A survey of intraseasonal, seasonal, and interannual precipitation and 850hPa winds for various monsoon regimes around the world is presented for the Community Earth System Model version 2 (CESM2) compared to observations and the previous generation CESM1. In CESM2 the south Asian monsoon has a reduction of excessive precipitation in the western Indian Ocean and an increase of precipitation in the

In the atmosphere, microphysics refers to the microscale processes that affect cloud and precipitation particles and is a key linkage among the various components of Earth's atmospheric water and energy cycles. The representation of microphysical processes in models continues to pose a major challenge leading to uncertainty in numerical weather forecasts and climate simulations. In this paper, the

To increase our capability to predict Arctic sea ice and climate, we have developed a coupled atmosphere‐sea ice‐ocean model configured for the pan‐Arctic with sufficient flexibility. The Los Alamos Sea Ice Model is coupled with the Weather Research and Forecasting Model and the Regional Ocean Modeling System in the Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport modeling system. It is well known

Deep convective clouds reach the upper troposphere (8–15 km height). In addition to moisture and aerosol particles, they can bring aerosol precursor gases and other reactive trace gases from the planetary boundary layer to the cloud top. In this paper, we present a method to estimate trace gas transport based on the analysis of individual air parcel trajectories. Large eddy simulation of an idealized

This paper introduces the Flexible Global Ocean–Atmosphere–Land System Model: Grid‐Point Version 3 (FGOALS‐g3) and evaluates its basic performance based on some of its participation in the sixth phase of the Coupled Model Intercomparison Project (CMIP6) experiments. Our results show that many significant improvements have been achieved by FGOALS‐g3 in terms of climatological mean states, variabilities

This paper documents development of a multiple‐Graphics Processing Unit (GPU) version of FUNWAVE‐Total Variation Diminishing (TVD), an open‐source model for solving the fully nonlinear Boussinesq wave equations using a high‐order TVD solver. The numerical schemes of FUNWAVE‐TVD, including Cartesian and spherical coordinates, are rewritten using CUDA Fortran, with inter‐GPU communication facilitated

This work introduces a methodology for optimizing neural network models using a combination of continuous and categorical binary indices in the context of precipitation forecasting. Probability of detection and false alarm rate are popular metrics used in the verification of precipitation models. However, machine learning models trained using gradient descent cannot be optimized based on these metrics

In a modeled environment of rotating radiative‐convective equilibrium (RCE), convective self‐aggregation may take the form of spontaneous tropical cyclogenesis. We investigate the processes leading to tropical cyclogenesis in idealized simulations with a three‐dimensional cloud‐permitting model configured in rotating RCE, in which the background planetary vorticity is varied across f‐plane cases to

Cloud computing platforms can facilitate the use of Earth science models by providing immediate access to fully configured software, massive computing power, and large input data sets. However, slow internode communication performance has previously discouraged the use of cloud platforms for massively parallel simulations. Here we show that recent advances in the network performance on the Amazon Web

The National Aeronautics and Space Administration‐Japan Aerospace Exploration Agency Global Precipitation Measurement (GPM) mission consists of a multisatellite constellation that provides real‐time or near‐real‐time global observations of rain and snow. In this study, GPM Level 3 Integrated Multi‐satellitE Retrievals for GPM (IMERG) and Level 2 GPM Microwave Imager Goddard Profiling rainfall products

The gust fronts of convective cold pools (CPs) are increasingly recognized as loci of enhanced triggering for subsequent convective cells. It has so far been difficult to track these gust fronts in high‐resolution data, such as large eddy simulations (LES)—rendering mechanistic analysis of CP interaction incomplete. Here, a simple tracking method is defined, tested, and applied, which uses horizontal

A climate model's ability to reproduce observed historical warming is sometimes viewed as a measure of quality. Yet, for practical reasons it cannot be considered a purely empirical result of the modeling efforts because the desired result is known in advance and so is a potential target of tuning. Here we report how the latest edition of the Max Planck Institute for Meteorology Earth System Models

The explicit coupling at metre and second scales of vegetation's responses to the atmospheric‐boundary layer dynamics drives a dynamic heterogeneity that influences canopy‐top fluxes and cloud formation. Focusing on a representative day during the Amazonian dry season, we investigate the diurnal cycle of energy, moisture and carbon dioxide at the canopy top, and the transition from clear to cloudy

A mountain watershed network model is presented for use in decadal to centurial estimation of source‐to‐sink sediment dynamics. The model requires limited input parameters and can be effectively applied over spatial scales relevant to management of reservoirs, lakes, streams, and watersheds (1–100 km2). The model operates over a connected stream network of Strahler‐ordered segments. The model is driven

In China, irrigation is widespread in 40.7% cropland to sustain crop yields. By its action on water cycle, irrigation affects water resources and local climate. In this study, a new irrigation module, including flood and paddy irrigation technologies, was developed in the ORCHIDEE‐CROP land surface model which describes crop phenology and growth in order to estimate irrigation demands over China from

No abstract is available for this article.

This paper describes and evaluates the assimilation component of a seamless sea ice prediction system, which is developed based on the fully coupled Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research Climate Model (AWI‐CM, v1.1). Its ocean/ice component with unstructured‐mesh discretization and smoothly varying spatial resolution enables seamless sea ice prediction across a wide

Ecosystem function (particularly CO2 fluxes and the subsequent atmospheric transport), synoptic‐scale weather (e.g., midlatitude cyclones), and interactions between ecosystems and the atmosphere can be investigated using a weather‐biosphere‐online‐coupled model. The Vegetation Photosynthesis and Respiration Model (VPRM) was coupled with the Weather Research and Forecasting (WRF) model in 2008 to simulate

During spring 2011, an extreme flood occurred along the Richelieu River located in southern Quebec, Canada. The Richelieu River is the last section of the complex Richelieu basin, which is composed of the large Lake Champlain located in a valley between two large mountains. Previous attempts in reproducing the Richelieu River flow relied on the use of simplified lumped models and showed mixed results

Land surface models (LSMs) are a vital tool for understanding, projecting, and predicting the dynamics of the land surface and its role within the Earth system, under global change. Driven by the need to address a set of key questions, LSMs have grown in complexity from simplified representations of land surface biophysics to encompass a broad set of interrelated processes spanning the disciplines

This study evaluates the impact of assimilating moderate resolution imaging spectroradiometer (MODIS) aerosol optical depth (AOD) data using different data assimilation (DA) methods on dust analyses and forecasts over North Africa and tropical North Atlantic. To do so, seven experiments are conducted using the Weather Research and Forecasting dust model and the Gridpoint Statistical Interpolation analysis

The importance of air‐sea coupling in the simulation and prediction of the Madden‐Julian Oscillation (MJO) has been well established. However, it remains unclear how air‐sea coupling modulates the convection and related oceanic features on the subdaily scale. Based on a regional cloud‐permitting coupled model, we evaluated the impact of the air‐sea coupling on the convection during the convectively

Regional climate models (RCMs) are usually initialized and driven through the boundaries of their limited area domain by data provided by global models (GCMs). The mismatch between the low‐resolution GCM initial conditions and RCM's high resolution introduces physical inconsistencies between the various components of the RCM. These inconsistencies can be resolved by running the RCM during a period

Climate engineering (CE) measures are increasingly discussed when dealing with the adverse impacts of climate change. While much research has focused on individual methods, few studies attempt to compare and rank the effectiveness of these measures. Furthermore, model uncertainties are seldom acknowledged and lesser still, estimated when CE scenarios are assessed. In this work, we quantify the variance

The explicit calculation of stratospheric ozone in global climate models still comes at a high computational cost. Here, the usefulness of a linear ozone parameterization in a global climate model is assessed by comparing it to an explicit chemistry scheme and to observations. It is shown that the annual mean total ozone column and the tropical ozone profile agree well for the linear and the explicit

Most general circulation models compute radiation fluxes by assuming that water vapor is uniform within individual grid layers, which leads to an underestimation of satellite‐observed longwave (LW) cloud radiative forcing (LWCF). To fix this problem, we calculated water vapor content separately for clear and cloudy portions and used them to compute LW radiation. The impacts of this modification were

Carbon (C) enters into the terrestrial ecosystems via photosynthesis and cycles through the system together with other essential nutrients (i.e., nitrogen [N] and phosphorus [P]). Such a strong coupling of C, N, and P leads to the theoretical prediction that limited nutrient availability will limit photosynthesis rate, plant growth, and future terrestrial C dynamics. However, the lack of reliable information

Wetlands are one of the most important terrestrial ecosystems for land‐atmosphere CH4 exchange. A new process‐based, biophysical model to quantify CH4 emissions from natural wetlands was developed and integrated into a terrestrial ecosystem model (Integrated Biosphere Simulator). The new model represents a multisubstance system (CH4, O2, CO2, and H2) and describes CH4 production, oxidation, and three

We describe the scientific and technical implementation of two models for a core set of experiments contributing to the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The models used are the physical atmosphere‐land‐ocean‐sea ice model HadGEM3‐GC3.1 and the Earth system model UKESM1 which adds a carbon‐nitrogen cycle and atmospheric chemistry to HadGEM3‐GC3.1. The model results are

Climate models rely on parameterizations of a variety of processes in the atmospheric physics, but a common concern is that the temporal resolution is too coarse to consistently resolve the behavior that individual parameterizations are designed to capture. This study examines timescales numerically derived from the Morrison‐Gettelman (MG2) microphysics as implemented within the Energy Exascale Earth

The configuration of the Met Office Unified Model being submitted to CMIP6 has a high climate sensitivity. Previous studies have suggested that the impact of model changes on initial tendencies in numerical weather prediction (NWP) should be used to guide their suitability for inclusion in climate models. In this study we assess, using NWP experiments, the atmospheric model changes which lead to the

A new weakly coupled data assimilation (CDA) system based on the dimension‐reduced projection four‐dimensional variational data assimilation (DRP‐4DVar) with a simplified off‐line localization technique and a fully coupled model, i.e., the Grid‐point Version 2 of Flexible Global Ocean‐Atmosphere‐Land System Model (FGOALS‐g2), was developed for the initialization of decadal predictions. A 1‐month assimilation

The Community Earth System Model version 2 (CESM2) includes a detailed representation of chemistry throughout the atmosphere in the Community Atmosphere Model with chemistry and Whole Atmosphere Community Climate Model configurations. These model configurations use the Model for Ozone and Related chemical Tracers (MOZART) family of chemical mechanisms, covering the troposphere, stratosphere, mesosphere

The editors thank the 2019 peer reviewers

A simple parameter nudging procedure is described that systematically reduces near‐analysis time errors in the surface net shortwave flux in the Navy ESPC (Earth System Prediction Capability) system, a global coupled forecast system that is the product of a continuing development effort at the U. S. Naval Research Laboratory. The procedure generates geographically varying perturbations to one of the

For simulations intended to study the influence of anthropogenic forcing on climate, temporal stability of the Earth's natural heat, freshwater and biogeochemical budgets is critical. Achieving such coupled model equilibration is scientifically and computationally challenging. We describe the protocol used to spin‐up the UK Earth system model (UKESM1) with respect to pre‐industrial forcing for use

We present the latest version of the ISBA‐CTRIP land surface system, focusing on the representation of the land carbon cycle. We review the main improvements since the year 2012, mainly added modules for wild fires, carbon leaching through soil and transport of dissolved organic carbon to the ocean, and land cover changes, but also improved representation of photosynthesis, respiration, and plant functional

In this study, we use the Community Land Model version 5 (CLM5) to investigate how irrigation modulates hydrologic and biogeochemical dynamics in the Upper Columbia‐Priest Rapids (UCPR) watershed, a typical semi‐arid watershed located in the north‐western United States dominated by cropland. To our knowledge, this constitutes the first application of CLM5 with landscape heterogeneity fully resolved

To study the influence of convective momentum transport (CMT) on wind, boundary layer and cloud evolution in a marine cold air outbreak (CAO) we use Large‐Eddy Simulations subject to different baroclinicity (wind shear) but similar surface forcing. The simulated domain is large enough to develop typical mesoscale cellular convective structures. We find that a maximum friction induced by momentum transport

Vertical mixing is often regarded as the Achilles' heel of ocean models. In particular, few models include a comprehensive and energy‐constrained parameterization of mixing by internal ocean tides. Here, we present an energy‐conserving mixing scheme which accounts for the local breaking of high‐mode internal tides and the distant dissipation of low‐mode internal tides. The scheme relies on four static

The implementation of boundary conditions is a key aspect of climate simulations. We describe here how the Climate Model Intercomparison Project phase 6 (CMIP6) forcing datasets have been processed and implemented in version 6 of the IPSL climate model (IPSL‐CM6A‐LR) as used for CMIP6. Details peculiar to some of the Model Intercomparison Projects (MIPs) are also described. IPSL‐CM6A‐LR is run without

The authors analyze the global statistics of tropical cyclones (TCs) undergoing extratropical transition (ET) in the Forecast‐oriented Low Ocean Resolution version of CM2.5 with Flux Adjustment (FLOR‐FA). The Cyclone Phase Space (CPS) is used to diagnose ET. A simulation of the recent historical climate is analyzed and compared with data from the Japanese 55‐year Reanalysis (JRA‐55), and then a simulation

Using successive versions of a global climate model, we show how convective transport to the free troposphere of the humidity evaporated at the surface or, reciprocally, entrainment of dry air from the free troposphere into the mixed layer, controls surface evaporative cooling and then sea surface temperature. This control is as important as the radiative effect of boundary layer clouds on radiation

This study presents the version of the LMDZ global atmospheric model used as the atmospheric component of the Institut Pierre Simon Laplace coupled model (IPSL‐CM6A‐LR) to contribute to the 6th phase of the international Coupled Model Intercomparison Project (CMIP6). This LMDZ6A version includes original convective parameterizations that define the LMDZ 'New Physics’: a mass flux parameterization of

Modeling the net carbon balance is challenging due to the knowledge gaps in the variability and processes controlling gross carbon fluxes. Terrestrial carbon cycle modeling is susceptible to several sources of bias, including meteorological uncertainty, model structural uncertainty, and model parametric uncertainty. To determine the impact of these uncertainties, we compare three model‐derived representations

This study extended a method to evaluate rain microphysics in a shallow cumulus regime using space‐borne radar observational data with a forward simulator of satellite measurements. We compared a two‐moment bulk scheme with a two‐moment bin scheme. A dynamic‐kinematic model was used to isolate cloud microphysics processes from their interactions with dynamics. The relationships between horizontally

The Princeton environment‐dependent probabilistic tropical Cyclone (PepC) model is developed for generating synthetic TCs to support TC risk assessment. PepC consists of three components: a hierarchical Poisson genesis model, an analog‐wind track model, and a Markov intensity model. The three model components are dependent on environmental variables that vary with the climate, including potential intensity

Climate model components utilizing unstructured meshes enable variable‐resolution, regionally enhanced simulations within global domains. Here we investigate the relationship between mesh quality and simulation statistics using the JIGSAW unstructured meshing library and the Model for Prediction Across Scales‐Ocean (MPAS‐Ocean) with a focus on Gulf Stream dynamics. In the base configuration, the refined