Implementing irrigation techniques in CESM2

2020 ◽  
Author(s):  
Yi Yao ◽  
Sean Swenson ◽  
Dave Lawrence ◽  
Wim Thiery
Keyword(s):  
Land Surface ◽  
Surface Fluxes ◽  
System Model ◽  
Earth System ◽  
Irrigation Scheme ◽  
Irrigation Systems ◽  
Community Land Model ◽  
Community Earth System Model ◽  
Induced Changes ◽  
Earth System Models

<p>Several recent studies have highlighted the importance of irrigation-induced changes in climate. Earth system models are a common tool to address this question, and to this end, irrigation is increasingly being represented in their land surface modules. Despite this evolution, currently, none of them considers different irrigation techniques. Here we develop and test a new parameterization that represents irrigation activities in the Community Land Model version 5 (CLM5) and considers three main irrigation techniques (surface, sprinkler and drip irrigation). Using global maps of the areas equipped by different irrigation systems, we will employ version 2 of the Community Earth System Model (CESM2) and its improved irrigation representation to detect the impacts of irrigation on climate. Two control experiments are designed, one with the new irrigation scheme and another with the original one. We will conduct an evaluation by comparing the simulated results against observed surface fluxes and meteorological variables. Subsequently, the differences between the experiments will be analyzed to quantify the impacts of irrigation on climate. We anticipate that our results will uncover whether considering different irrigation schemes is of value for exploring irrigate-induced impacts on climate.</p>

Evolution of the monsoon system over the past 250 million years

2021 ◽  
Author(s):  
Yongyun Hu ◽  
Jiaqi Guo ◽  
Xiang Li ◽  
Jiaenjing Lan ◽  
Qifan Lin ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Land Surface ◽  
System Model ◽  
Earth System ◽  
Global Monsoon ◽  
The Past ◽  
Climate Simulations ◽  
Monsoon System ◽  
Community Earth System Model ◽  
Carbon Dioxide Co2

<p>The evolution of continents over the past 250 million year is remarked by the breakup of the Pangea supercontinent. The changes of continents must have important influences on regional and global monsoon systems because monsoons are primarily a result of land-sea thermal contrast.</p><p>To study how the monsoon system had been evolved with continent changes over the past 250 million years, we carried out a series of climate simulations, using the Community Earth System Model (CESM). Changes in continents, mountain building, solar radiation, and carbon dioxide (CO2) are all considered in the simulations. In the present talk, we will present our preliminary simulation results of how the mega-monsoon associated with the supercontinent Pangea evolved into the six regional monsoons at the present over the past 250 million years. We will also demonstrate ocean circulation changes with different continent distributions, such as ENSO, and its influences on regional monsoons. Monsoon impacts on land-surface processes and the associated carbon-cycle will be also presented.</p>

scholarly journals Snowpack and firn densification in the Energy Exascale Earth System Model (E3SM) (version 1.2)

2020 ◽  
Author(s):  
Adam M. Schneider ◽  
Charles S. Zender ◽  
Stephen F. Price
Keyword(s):  
Empirical Model ◽  
Land Surface ◽  
Large Fraction ◽  
Ice Sheets ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Community Land Model ◽  
Semi Empirical ◽  
The Antarctic

Abstract. Earth's largest island, Greenland, and the Antarctic continent are both covered by massive ice sheets. A large fraction of their surfaces consist of multi-year snow, known as firn, which has undergone a process of densification since falling from the atmosphere. Until now this firn densification has not been fully accounted for in the U.S. Department of Energy's Energy Exascale Earth System Model (E3SM). Here, we expand the E3SM Land Model (ELM) snowpack from 1 m to up to 60 m to enable more accurate simulation of snowpack evolution. We test four densification models in a series of century-scale land surface simulations forced by atmospheric re-analyses, and evaluate these parameterizations against empirical density-versus-depth data. To tailor candidate densification models for use across the ice sheets' dry-snow zones, we optimize parameters using a regularized least squares algorithm applied to two distinct stages of densification. We find that a dynamic implementation of a semi-empirical compaction model, originally calibrated to measurements from the Antarctic peninsula, gives results more consistent with ice core measurements from the cold, dry snow zones of Greenland and Antarctica, compared to when using the original ELM snow compaction physics. In its latest release, the Community Land Model (CLM) (version 5) provides updated snow compaction physics that we test in ELM, resulting in top 10 m firn densities that are in better agreement with observations than densities simulated with the semi-empirical model. Below 10 m, however, the semi-empirical model gives results that more closely match observations, while the current CLM(v5) compaction physics predict firn densities that increase too slowly with depth and are thus unable to simulate pore close off (a phenomenon of particular interest to paleoclimate studies). Because snow and firn density play roles in snowpack albedo, liquid water storage, and ice sheet surface mass balance, these improvements will contribute to broader E3SM efforts to simulate the response of land ice to atmospheric forcing and the resulting impacts on global sea level.

scholarly journals Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0)

2017 ◽  
Author(s):  
Daniel J. Milroy ◽  
Allison H. Baker ◽  
Dorit M. Hammerling ◽  
Elizabeth R. Jessup
Keyword(s):  
Atmospheric Model ◽  
Earth System Model ◽  
System Model ◽  
Small Scale ◽  
Earth System ◽  
Consistency Test ◽  
Robust Test ◽  
Community Land Model ◽  
Community Earth System Model ◽  
Statistical Consistency

Abstract. The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. This objective test provides a statistical measurement of consistency between an accepted ensemble created by small initial temperature perturbations and a test set of CESM simulations. In this work, we extend the CESM-ECT suite by the addition of an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model (CAM) output after only nine model time steps. We demonstrate that adequate ensemble variability is achieved with instantaneous variable values at the ninth step, despite rapid perturbation growth and heterogeneous variable spread. We refer to this new test as the Ultra-Fast CAM Ensemble Consistency Test (UF-CAM-ECT) and demonstrate its effectiveness in practice, including its ability to detect small-scale events and its applicability to the Community Land Model (CLM). The new ultra-fast test facilitates CESM development, porting, and optimization efforts, particularly when used to complement information from the original CESM-ECT suite of tools.

scholarly journals Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0)

2018 ◽  
Vol 11 (2) ◽  
pp. 697-711 ◽  
Author(s):  
Daniel J. Milroy ◽  
Allison H. Baker ◽  
Dorit M. Hammerling ◽  
Elizabeth R. Jessup
Keyword(s):  
Atmospheric Model ◽  
Earth System Model ◽  
System Model ◽  
Small Scale ◽  
Earth System ◽  
Consistency Test ◽  
Robust Test ◽  
Community Land Model ◽  
Community Earth System Model ◽  
Statistical Consistency

Abstract. The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. This objective test provides a statistical measurement of consistency between an accepted ensemble created by small initial temperature perturbations and a test set of CESM simulations. In this work, we extend the CESM-ECT suite with an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model (CAM) output after only nine model time steps. We demonstrate that adequate ensemble variability is achieved with instantaneous variable values at the ninth step, despite rapid perturbation growth and heterogeneous variable spread. We refer to this new test as the Ultra-Fast CAM Ensemble Consistency Test (UF-CAM-ECT) and demonstrate its effectiveness in practice, including its ability to detect small-scale events and its applicability to the Community Land Model (CLM). The new ultra-fast test facilitates CESM development, porting, and optimization efforts, particularly when used to complement information from the original CESM-ECT suite of tools.

scholarly journals A subbasin-based framework to represent land surface processes in an Earth system model

2014 ◽  
Vol 7 (3) ◽  
pp. 947-963 ◽  
Author(s):  
T. K. Tesfa ◽  
H.-Y. Li ◽  
L. R. Leung ◽  
M. Huang ◽  
Y. Ke ◽  
...  
Keyword(s):  
Land Surface ◽  
Traditional Approach ◽  
Earth System Model ◽  
System Model ◽  
Surface Processes ◽  
Earth System ◽  
Modeling Framework ◽  
Land Surface Processes ◽  
Community Land Model ◽  
Grid Based

Abstract. Realistically representing spatial heterogeneity and lateral land surface processes within and between modeling units in Earth system models is important because of their implications to surface energy and water exchanges. The traditional approach of using regular grids as computational units in land surface models may lead to inadequate representation of subgrid heterogeneity and lateral movements of water, energy and carbon fluxes. Here a subbasin-based framework is introduced in the Community Land Model (CLM), which is the land component of the Community Earth System Model (CESM). Local processes are represented in each subbasin on a pseudo-grid matrix with no significant modifications to the existing CLM modeling structure. Lateral routing of water within and between subbasins is simulated with the subbasin version of a recently developed physically based routing model, Model for Scale Adaptive River Transport (MOSART). The framework is implemented in two topographically and climatically contrasting regions of the US: the Pacific Northwest and the Midwest. The relative merits of this modeling framework, with greater emphasis on scalability (i.e., ability to perform consistently across spatial resolutions) in streamflow simulation compared to the grid-based modeling framework are investigated by performing simulations at 0.125°, 0.25°, 0.5°, and 1° spatial resolutions. Comparison of the two frameworks at the finest spatial resolution showed that a small difference between the averaged forcing could lead to a larger difference in the simulated runoff and streamflow because of nonlinear processes. More systematic comparisons conducted using statistical metrics calculated between each coarse resolution and the corresponding 0.125°-resolution simulations showed superior scalability in simulating both peak and mean streamflow for the subbasin based over the grid-based modeling framework. Scalability advantages are driven by a combination of improved consistency in runoff generation and the routing processes across spatial resolutions.

Results from An Ensemble Reanalysis with the Community Earth System Model 2.1

2020 ◽  
Author(s):  
Kevin Raeder ◽  
Jeffrey Anderson ◽  
TImothy Hoar ◽  
Nancy Collins ◽  
Moha El Gharamti
Keyword(s):  
Sea Ice ◽  
Land Surface ◽  
Land Surface Model ◽  
Atmospheric Model ◽  
Earth System Model ◽  
System Model ◽  
Surface Model ◽  
Earth System ◽  
Atmospheric Forcing ◽  
Community Earth System Model

<p>The National Center for Atmospheric Research (NCAR) has recently released version 2.1 of the Community Earth System Model (CESM 2.1). A twenty-year, 80-member ensemble atmospheric reanalysis with 1-degree resolution in the CAM6 atmospheric model is being produced using NCAR’s Data Assimilation Research Testbed (DART) to support a variety of climate research goals. A standard configuration of CAM and the CLM5 land surface model will be coupled to a prescribed ocean and sea ice. Eventually, the reanalyisis will generate a final product that extends from 1999 to the present. Observations being assimilated include in situ observations used in the operational NCEP CFSR reanalysis along with GPS occultation observations and remote sensing temperature retrievals. The primary goal is to provide an ensemble of atmospheric forcing that can be used to generate additional ensemble reanalyses for other components of CESM including CLM, the POP and MOM6 ocean models, and the CICE sea ice model. Highlights of results from the first 10-years of the reanalysis will be presented. Results will include evaluation of short-term forecasts in observation space for root mean square error, ensemble spread, and ensemble consistency. In addition, key aspects of the atmospheric forcing files for other components of the climate system will be discussed. </p>

Leveraging clustering and geostatistics to improve the modeling of sub-grid land-atmosphere interactions in Earth system models

2021 ◽  
Author(s):  
Nathaniel Chaney ◽  
Laura Torres-Rojas ◽  
Jason Simon
Keyword(s):  
Correlation Length ◽  
Land Surface ◽  
Spatial Organization ◽  
Sensible Heat Flux ◽  
Surface Fluxes ◽  
Surface Model ◽  
Earth System ◽  
Time Step ◽  
System Models ◽  
Earth System Models

<p>Multi-scale spatial heterogeneity over the land surface (meter to km scales) can play a pivotal role in the development of clouds and precipitation. To model this process within Earth system models (ESMs; ~100 km spatial resolution), sub-grid reduced-order modeling approaches are used. More specifically, state-of-the-art ESMs sub-divide the land surface of each grid cell into representative clusters (e.g., forest, lakes, and grasslands) that are learned a-priori from available high-resolution satellite remote sensing data (e.g., STRM, Landsat and Sentinel-2) via clustering. However, until recently, these clusters have remained spatially agnostic making it infeasible to infer spatial statistics of the modeled sub-grid heterogeneity over land that are required by the atmospheric model to ensure proper development of simulated convection (e.g., spatial correlation length of surface evaporation). This presentation will introduce an approach that leverages the precomputed cluster positions in space to construct an effective and efficient approach to assemble the experimental semivariogram from the sub-grid clusters within ESMs. As a proof of concept, we will show results by applying the novel method on sub-grid model output from the HydroBlocks land surface model over a 100 km domain centered at the Southern Great Plains site in Oklahoma, United States. Furthermore, to illustrate the added-value that the experimental semivariograms will have towards improving the modeling of land-atmosphere interactions, we will illustrate the results from large-eddy simulations over the domain that show how differences in correlation length of surface fluxes can have, at times, a dramatic impact on the development of clouds and convection in the atmosphere. When implemented in ESMs, this new approach will make it possible to infer the modeled sub-grid spatial organization of the surface fluxes (e.g., sensible heat flux) per time step with negligible increases in computation expense.</p>

scholarly journals When Less Is More: Opening the Door to Simpler Climate Models

Eos ◽  
2017 ◽  
Author(s):  
L. Polvani ◽  
A. Clement ◽  
B. Medeiros ◽  
J. Benedict ◽  
I. Simpson
Keyword(s):  
Climate Models ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Less Is More ◽  
System Models ◽  
Model Project ◽  
Community Earth System Model ◽  
Earth System Models

Earth system models are resource intensive and complex. To cut through this complexity, the Community Earth System Model project will now be embracing a hierarchy of simpler climate models.

scholarly journals Sensitivities and Responses of Land Surface Temperature to Deforestation-Induced Biophysical Changes in Two Global Earth System Models

2020 ◽  
Vol 33 (19) ◽  
pp. 8381-8399
Author(s):  
Weilin Liao ◽  
Xiaoping Liu ◽  
Elizabeth Burakowski ◽  
Dagang Wang ◽  
Linying Wang ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Surface Resistance ◽  
Aerodynamic Resistance ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Biophysical Changes ◽  
Earth System Models

AbstractWhile the significance of quantifying the biophysical effects of deforestation is rarely disputed, the sensitivities of land surface temperature (LST) to deforestation-induced changes in different biophysical factors (e.g., albedo, aerodynamic resistance, and surface resistance) and the relative importance of those biophysical changes remain elusive. Based on the subgrid-scale outputs from two global Earth system models (ESMs, i.e., the Geophysical Fluid Dynamics Laboratory Earth System Model and the Community Earth System Model) and an improved attribution framework, the sensitivities and responses of LST to deforestation are examined. Both models show that changes in aerodynamic resistance are the most important factor responsible for LST changes, with other factors such as albedo and surface resistance playing secondary but important roles. However, the magnitude of the contributions from different biophysical factors to LST changes is quite different for the two ESMs. We find that the differences between the two models in terms of the sensitivities are smaller than those of the corresponding biophysical changes, indicating that the dissimilarity between the two models in terms of LST responses to deforestation is more related to the magnitude of biophysical changes. It is the first time that the attribution of subgrid surface temperature variability is comprehensively compared based on simulations with two commonly used global ESMs. This study yields new insights into the similarity and dissimilarity in terms of how the biophysical processes are represented in different ESMs and further improves our understanding of how deforestation impacts on the local surface climate.

scholarly journals A subbasin-based framework to represent land surface processes in an Earth System Model

2013 ◽  
Vol 6 (2) ◽  
pp. 2699-2730 ◽  
Author(s):  
H.-Y. Li ◽  
M. Huang ◽  
T. Tesfa ◽  
Y. Ke ◽  
Y. Sun ◽  
...  
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
System Model ◽  
Surface Processes ◽  
Earth System ◽  
Land Surface Models ◽  
Land Surface Processes ◽  
Surface Models ◽  
Earth System Models ◽  
Grid Based

Abstract. Realistically representing spatial heterogeneity and lateral land surface processes within and between modeling units in earth system models is important because of their implications to surface energy and water exchanges. The traditional approach of using regular grids as computational units in land surface models and earth system models may lead to inadequate representation of subgrid heterogeneity and lateral movements of water, energy and carbon fluxes, especially when the grid resolution increases. Here a new subbasin-based framework is introduced in the Community Land Model (CLM), which is the land component of the Community Earth System Model (CESM). Local processes are represented assuming each subbasin as a grid cell on a pseudo grid matrix with no significant modifications to the existing CLM modeling structure. Lateral routing of water within and between subbasins is simulated with the subbasin version of a recently-developed physically based routing model, Model for Scale Adaptive River Routing (MOSART). As an illustration, this new framework is implemented in the topographically diverse region of the US Pacific Northwest. The modeling units (subbasins) are delineated from high-resolution Digital Elevation Models (DEMs) while atmospheric forcing and surface parameters are remapped from the corresponding high resolution datasets. The impacts of this representation on simulating hydrologic processes are explored by comparing it with the default (grid-based) CLM representation. In addition, the effects of DEM resolution on parameterizing topography and the subsequent effects on runoff processes are investigated. Limited model evaluation and comparison showed that small difference between the averaged forcing can lead to more significant difference in the simulated runoff and streamflow because of nonlinear lateral processes. Topographic indices derived from high resolution DEMs may not improve the overall water balance, but affect the partitioning between surface and subsurface runoff. More systematic analyses are needed to determine the relative merits of the subbasin representation compared to the commonly used grid-based representation, especially when land surface models are approaching higher resolutions.

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