• Issue
    Volume 13, Issue 10
    October 2021

Research Article

Open Access

Role of Microphysics and Convective Autoconversion for the Better Simulation of Tropical Intraseasonal Oscillations (MISO and MJO)

  • First Published: 26 August 2021
Key Points

  • Importance of proper “autoconversion” coefficients in Coupled Global Climate Model's convective and microphysical schemes for Monsoon Intraseasonal Oscillation (MISO) and Madden Julian Oscillation (MJO)

  • The study has unveiled the linkage between mean Indian summer monsoon rainfall (ISMR) and the sub-seasonal variability, proper convection modulated by “áutoconversion”

  • High fidelity in the simulation of MISO and MJO with better high cloud and stratiform rain fraction leads to the improved mean ISMR

Open Access

Description of Dust Emission Parameterization in CAS-ESM2 and Its Simulation of Global Dust Cycle and East Asian Dust Events

  • First Published: 12 September 2021
Key Points

  • Chinese Academy of Sciences Earth System Model version 2 (CAS-ESM2) with a physically based dust emission scheme provides a new and promising solution to simulate global dust emissions

  • CAS-ESM2 captures the main global dust emission regions and reproduces observed dust depositions and surface dust concentrations

  • The weaker dust events are compensated by overestimated dust event frequency and duration to produce reasonable means in East Asia

Open Access

Enhancing Understanding of the Hydrological Cycle via Pairing of Process-Oriented and Isotope Ratio Tracers

  • First Published: 20 September 2021
Key Points

  • Process-based tracers in iCAM6 allow for expanded hypothesis testing of water cycle change and more informed use of water isotope ratios

  • The degree of parcel rainout is a primary control on both δ18O and d-excess, consistent with Rayleigh theory

  • Water vapor residence time does not strongly influence precipitation δ18O, but evaporative conditions influence precipitation d-excess

Open Access

Machine Learning-Based Modeling of Vegetation Leaf Area Index and Gross Primary Productivity Across North America and Comparison With a Process-Based Model

  • First Published: 08 October 2021
Key Points

  • We developed an interpretable machine learning scheme to simulate leaf area index (LAI) and gross primary productivity (GPP) via only meteorological variables

  • The results demonstrated that the machine learning models perform well on simulating the time series of both LAI and GPP

  • The machine learning models provide benchmarking accuracies for future developments of the process-based models

Open Access

Representing Microphysical Uncertainty in Convective-Scale Data Assimilation Using Additive Noise

  • First Published: 04 October 2021
Key Points

  • Model simulations with two microphysical schemes are used to represent uncertainty in clouds and precipitation during data assimilation

  • In data assimilation, including the combination of microphysical and large-scale uncertainty improves the performance

  • The improvement is also significant for short-term ensemble forecasts of radar reflectivity and hourly precipitation

Open Access

Lagrangian Data Assimilation and Parameter Estimation of an Idealized Sea Ice Discrete Element Model

  • First Published: 30 August 2021
Key Points

  • An efficient Lagrangian data assimilation method is developed based on an idealized discrete element sea ice model

  • The method is highly accurate in recovering the unobserved balanced part of the ocean flow with large practical observational timestep

  • An expectation-maximization algorithm is developed to estimate individual floe thicknesses based on the assimilated floe velocities

Open Access

From Sugar to Flowers: A Transition of Shallow Cumulus Organization During ATOMIC

  • First Published: 16 September 2021
Key Points

  • Lagrangian large eddy simulation can reproduce the transition of shallow cumulus organization from sugar to flowers observed on February 2–3, 2020 during Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign

  • While large-scale upward vertical wind deepens the cloud layer, mesoscale wind renders moist areas moister assisting cloud organization

  • Stronger large-scale upward motion strengthens the mesoscale circulation and accelerates the sugar-to-flowers transition process

Open Access

An Improved Parameterization of Wind-Driven Turbulent Vertical Mixing Based on an Eddy-Resolving Climate Model

  • First Published: 08 October 2021
Key Points

  • A modified finescale parameterization (MFP) scheme is applied to an eddy-resolving Community Earth System Model (CESM)

  • The parameterized wind-driven vertical mixing in the CESM is validated against observations

  • Eddy-resolving CESM with MFP shows good skills in representing the wind-driven vertical mixing in the thermocline

Open Access

Learning Variational Data Assimilation Models and Solvers

  • First Published: 04 October 2021
Key Points

  • We develop a end-to-end neural architecture to design variational data assimilation models and solvers

  • We may jointly calibrate all the trainable components of the proposed scheme to optimize a data assimilation performance criterion

  • Applied to Lorenz-63 and Lorenz-96 case-studies, the proposed approach may improve and speed up the reconstruction performance

Open Access

Improved Weather Forecasting Using Neural Network Emulation for Radiation Parameterization

  • First Published: 04 October 2021
Key Points

  • A neural network emulator for radiation parameterization in a numerical weather prediction model was developed

  • It enabled the computational speed of radiation process by 60 or thousands (along with its infrequent use) times

  • It's accuracy was similar to the use of original scheme, compared with surface precipitation and temperature observations

Open Access

Conceptualizing Biogeochemical Reactions With an Ohm's Law Analogy

  • First Published: 05 October 2021
Key Points

  • Ohm's law is proposed to formulate biogeochemical reactions

  • Ohm's law successfully represents multiple-nutrient-colimited growth

  • Ohm's law may help improve and unify biogeochemical models

Open Access

Semi-Coupling of a Field-Scale Resolving Land-Surface Model and WRF-LES to Investigate the Influence of Land-Surface Heterogeneity on Cloud Development

  • First Published: 12 September 2021
Key Points

  • Large-eddy simulation is used to study fine-scale heterogeneity in land-atmosphere coupling

  • Spatial patterns from rainfall increase cloud production via mesoscale circulations

  • Sub-grid scale heterogeneity should ideally be included in global model parameterizations

Open Access

Simulated Spatial and Temporal Distribution of Freezing and Thawing Fronts in CAS-FGOALS-g3

  • First Published: 04 October 2021
Key Points

  • A new frozen soil algorithm, including freezing and thawing fronts, is implemented in the climate model CAS-FGOALS-g3

  • The updated model can capture changes of freezing and thawing fronts, which affects soil moisture and soil temperature

  • The active layer thickness shows increasing trends, while the maximum freeze depth shows decreasing trends

Open Access

Learning to Correct Climate Projection Biases

  • First Published: 04 October 2021
Key Points

  • Identify and correct climate projection biases using unpaired climate simulation and observation data

  • Regularize the data-driven bias corrector using statistical and dynamical constraints

  • Significant improvement of daily precipitation estimation regarding a broad range of spatiotemporal statistics

Open Access

Coupling the U.K. Earth System Model to Dynamic Models of the Greenland and Antarctic Ice Sheets

  • First Published: 28 September 2021
Key Points

  • A CMIP6 Earth System Model has been coupled to interactive models of both the Greenland and Antarctic ice sheets for the first time

  • Substantial technical challenges have been overcome, our solutions and their limitations are described

  • Our system simulates climate and ice sheet physics reasonably well, and is computationally stable when subject to extreme ice sheet retreat

Open Access

AMOC Variability and Watermass Transformations in the AWI Climate Model

  • First Published: 21 September 2021
Key Points

  • Patterns of sinking and diapycnal transformation across depth levels and isopycnals, respectively, can be used to study AMOC variability

  • The AMOC subpolar maximum is largely driven by internal transformations

  • The density framework illustrates the interplay between surface buoyancy flux and interior-mixing

Open Access

Impact of Assimilating High-Resolution Atmospheric Motion Vectors on Convective Scale Short-Term Forecasts: 1. Observing System Simulation Experiment (OSSE)

  • First Published: 27 September 2021
Key Points

  • GOES-R derived Atmospheric Motion Vector (AMV) product has the potential to benefit convective scale data assimilation and forecasts

  • The assimilation of GOES-R derived AMVs is performed through observing system simulation experiments of a supercell storm

  • The short-term forecast of the simulated severe weather event is improved when assimilating the AMV data

Open Access

A Joint Soil-Vegetation-Atmospheric Modeling Procedure of Water Isotopologues: Implementation and Application to Different Climate Zones With WRF-Hydro-Iso

  • First Published: 21 September 2021
Key Points

  • A new coupled atmospheric-hydrological regional modeling system of water isotopologues is presented

  • Land surface evaporation fractionation increases the isotopic concentrations in the rootzone

  • Lateral terrestrial water flow has a minor effect on isotopic concentrations in the rootzone

Open Access

Attribution of Snowpack Errors to Simulated Temperature and Precipitation in E3SMv1 Over the Contiguous United States

  • First Published: 12 September 2021
Key Points

  • Model snow water equivalent (SWE) errors in the atmosphere-land simulations are more attributed to temperature than precipitation errors

  • Model SWE and temperature trends in the atmosphere-land simulations are largely opposite those of observations in the Western contiguous United States

  • Model SWE trend errors are more sensitive to temperature and precipitation trend errors in the atmosphere-ocean simulations

Open Access

Impact of Assimilating High-Resolution Atmospheric Motion Vectors on Convective Scale Short-Term Forecasts: 2. Assimilation Experiments of GOES-16 Satellite Derived Winds

  • First Published: 26 September 2021
Key Points

  • Geostationary Operational Environmental Satellite-16 (GOES-R) derived atmospheric motion vector (AMV) product has the potential to benefit convective scale data assimilation and forecasts

  • The impact of assimilating GOES-R derived AMVs on short-range severe thunderstorm forecasts is evaluated

  • The short-range forecasts of three severe weather events are improved by AMV DA compared to the control experiment without any observations

Open Access

Modulation of the Bifurcation in Radiative-Convective Equilibrium by Gray-Zone Cloud and Turbulence Parameterizations

  • First Published: 18 September 2021
Key Points

  • Convective self-aggregation in radiative-convective equilibrium exhibits nonlinear dependence on cloud and turbulence parameterizations

  • Its emergence or suppression is governed by a bifurcation of the dynamical system, which is sensitive to subgrid processes in the gray zone

  • Bifurcation mechanisms might be barriers to climate predictability due to inherent uncertainties in cloud and turbulence parameterizations

Open Access

Forcing Convection to Aggregate Using Diabatic Heating Perturbations

  • First Published: 24 September 2021
Key Points

  • Can increase the degree of aggregation by using a shortwave radiative heating perturbation

  • Radiative heating perturbation incites a global thermally driven circulation

  • Shortwave radiative heating perturbation can aggregate convection at lower sea surface temperatures, even without typically crucial longwave feedbacks

Open Access

Weak Temperature Gradient Modeling of Convection in OTREC

  • First Published: 19 August 2021
Key Points

  • A new weak temperature gradient (WTG) convective model includes shear-induced ventilation by dry environmental air

  • WTG modeling of convection produces better agreement with observations when ventilation is turned on

  • Including the effects of ventilation on convection may be needed in weather and climate models

Open Access

On the Damping Time Scale of EVP Sea Ice Dynamics

  • First Published: 04 October 2021
Key Points

  • Elastic Viscous Plastic (EVP) stability can be improved by proper selection of the time scale governing the decay of elastic waves

  • A significant reduction of the required number of EVP sub-cycles can be achieved on high-resolution meshes

  • EVP and the modified EVP simulate very similar sea-ice thickness and concentration

Open Access

A New Open Source Implementation of Lagrangian Filtering: A Method to Identify Internal Waves in High-Resolution Simulations

  • First Published: 07 October 2021
Key Points

  • A new open source parallelized Python package to perform Lagrangian filtering is now available

  • The package implements an improved method for filtering internal waves from high-resolution numerical model output

  • The package may be applied to directly filter output from a number of common ocean models including MITgcm, Regional Ocean Modeling System and MOM5

Open Access

Assimilation of X-Band Phased-Array Radar Data With EnKF for the Analysis and Warning Forecast of a Tornadic Storm

  • First Published: 28 September 2021
Key Points

  • The impact of assimilating China's X-band Phased-Array radar (X-PAR) radar data on the analysis and forecast of a tornadic storm was first investigated using an Ensemble Kalman Filter system

  • The assimilation of X-PAR data helps to produce a more realistic-looking tornadic storm structure, especially at low levels

  • Increasing assimilation frequency of X-PAR data reduces the analysis error and subsequently improves the 8-min tornadic storm forecast

Issue Information

Open Access

Issue Information

  • First Published: 28 September 2021