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

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.

Download Full-text

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

Geoscientific Model Development Discussions ◽

10.5194/gmdd-6-2699-2013 ◽

2013 ◽

Vol 6 (2) ◽

pp. 2699-2730 ◽

Cited By ~ 5

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.

Download Full-text

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

10.5194/gmd-2020-247 ◽

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.

Download Full-text

The Canadian Earth System Model version 5 (CanESM5.0.3)

Geoscientific Model Development ◽

10.5194/gmd-12-4823-2019 ◽

2019 ◽

Vol 12 (11) ◽

pp. 4823-4873 ◽

Cited By ~ 58

Author(s):

Neil C. Swart ◽

Jason N. S. Cole ◽

Viatcheslav V. Kharin ◽

Mike Lazare ◽

John F. Scinocca ◽

...

Keyword(s):

Land Surface ◽

General Circulation ◽

Large Scale ◽

General Circulation Models ◽

Earth System Model ◽

System Model ◽

Historical Period ◽

Earth System ◽

Historical Climate ◽

Model Version

Abstract. The Canadian Earth System Model version 5 (CanESM5) is a global model developed to simulate historical climate change and variability, to make centennial-scale projections of future climate, and to produce initialized seasonal and decadal predictions. This paper describes the model components and their coupling, as well as various aspects of model development, including tuning, optimization, and a reproducibility strategy. We also document the stability of the model using a long control simulation, quantify the model's ability to reproduce large-scale features of the historical climate, and evaluate the response of the model to external forcing. CanESM5 is comprised of three-dimensional atmosphere (T63 spectral resolution equivalent roughly to 2.8∘) and ocean (nominally 1∘) general circulation models, a sea-ice model, a land surface scheme, and explicit land and ocean carbon cycle models. The model features relatively coarse resolution and high throughput, which facilitates the production of large ensembles. CanESM5 has a notably higher equilibrium climate sensitivity (5.6 K) than its predecessor, CanESM2 (3.7 K), which we briefly discuss, along with simulated changes over the historical period. CanESM5 simulations contribute to the Coupled Model Intercomparison Project phase 6 (CMIP6) and will be employed for climate science and service applications in Canada.

Download Full-text

The role of land surface dynamics in glacial inception: a study with the UVic Earth System Model

Climate Dynamics ◽

10.1007/s00382-003-0352-2 ◽

2003 ◽

Vol 21 (7-8) ◽

pp. 515-537 ◽

Cited By ~ 243

Author(s):

K. J. Meissner ◽

A. J. Weaver ◽

H. D. Matthews ◽

P. M. Cox

Keyword(s):

Land Surface ◽

Earth System Model ◽

System Model ◽

Earth System ◽

Surface Dynamics

Download Full-text

Separation of the Effects of Land and Climate Model Errors on Simulated Contemporary Land Carbon Cycle Trends in the MPI Earth System Model version 1*

Journal of Climate ◽

10.1175/jcli-d-13-00593.1 ◽

2014 ◽

Vol 28 (1) ◽

pp. 272-291 ◽

Cited By ~ 14

Author(s):

Daniela Dalmonech ◽

Sönke Zaehle ◽

Gregor J. Schürmann ◽

Victor Brovkin ◽

Christian Reick ◽

...

Keyword(s):

Land Surface ◽

Climate Model ◽

Earth System Model ◽

System Model ◽

Surface Model ◽

Earth System ◽

Model Errors ◽

Max Planck ◽

C Cycle ◽

C Stocks

Abstract The capacity of earth system models (ESMs) to make reliable projections of future atmospheric CO2 and climate is strongly dependent on the ability of the land surface model to adequately simulate the land carbon (C) cycle. Defining “adequate” performance of the land model requires an understanding of the contributions of climate model and land model errors to the land C cycle. Here, a benchmarking framework is applied based on significant, observed characteristics of the land C cycle for the contemporary period, for which sufficient evaluation data are available, to test the ability of the JSBACH land surface component of the Max Planck Institute Earth System Model (MPI-ESM) to simulate land C trends. Particular attention is given to the role of potential effects caused by climate biases, and therefore investigation is made of the results of model configurations in which JSBACH is interactively “coupled” to atmosphere and ocean components and of an “uncoupled” configuration, where JSBACH is driven by reconstructed meteorology. The ability of JSBACH to simulate the observed phase of phenology and seasonal C fluxes is not strongly affected by climate biases. Contrarily, noticeable differences in the simulated gross primary productivity and land C stocks emerge between coupled and uncoupled configurations, leading to significant differences in the decadal terrestrial C balance and its sensitivity to climate. These differences are strongly controlled by climate biases of the MPI-ESM, in particular those affecting soil moisture. To effectively characterize model performance, the potential effects of climate biases on the land C dynamics need to be considered during the development and calibration of land surface models.

Download Full-text

Sensitivity Study of Four Land Surface Schemes in the WRF Model

Advances in Meteorology ◽

10.1155/2010/167436 ◽

2010 ◽

Vol 2010 ◽

pp. 1-11 ◽

Cited By ~ 64

Author(s):

Jiming Jin ◽

Norman L. Miller ◽

Nicole Schlegel

Keyword(s):

Land Surface ◽

Wrf Model ◽

Sensitivity Study ◽

Surface Processes ◽

Maximum Temperature ◽

Weather Research And Forecasting ◽

Land Surface Processes ◽

Community Land Model ◽

Model Version ◽

Close Relationship

The Weather Research and Forecasting (WRF) model version 3.0 developed by the National Center for Atmospheric Research (NCAR) includes three land surface schemes: the simple soil thermal diffusion (STD) scheme, the Noah scheme, and the Rapid Update Cycle (RUC) scheme. We have recently coupled the sophisticated NCAR Community Land Model version 3 (CLM3) into WRF to better characterize land surface processes. Among these four land surface schemes, the STD scheme is the simplest in both structure and process physics. The Noah and RUC schemes are at the intermediate level of complexity. CLM3 includes the most sophisticated snow, soil, and vegetation physics among these land surface schemes. WRF simulations with all four land surface schemes over the western United States (WUS) were carried out for the 1 October 1995 through 30 September 1996. The results show that land surface processes strongly affect temperature simulations over the (WUS). As compared to observations, WRF-CLM3 with the highest complexity level significantly improves temperature simulations, except for the wintertime maximum temperature. Precipitation is dramatically overestimated by WRF with all four land surface schemes over the (WUS) analyzed in this study and does not show a close relationship with land surface processes.

Download Full-text

The Canadian Earth System Model version 5 (CanESM5.0.3)

10.5194/gmd-2019-177 ◽

2019 ◽

Cited By ~ 5

Author(s):

Neil C. Swart ◽

Jason N. S. Cole ◽

Viatcheslav V. Kharin ◽

Mike Lazare ◽

John F. Scinocca ◽

...

Keyword(s):

Land Surface ◽

General Circulation ◽

Large Scale ◽

General Circulation Models ◽

Earth System Model ◽

System Model ◽

Historical Period ◽

Earth System ◽

Historical Climate ◽

Model Version

Abstract. The Canadian Earth System Model version 5 (CanESM5) is a global model developed to simulate historical climate change and variability, to make centennial scale projections of future climate, and to produce initialized seasonal and decadal predictions. This paper describes the model components and their coupling, as well as various aspects of model development, including tuning, optimization and a reproducibility strategy. We also document the stability of the model using a long control simulation, quantify the model's ability to reproduce large scale features of the historical climate, and evaluate the response of the model to external forcing. CanESM5 is comprised of three dimensional atmosphere (T63 spectral resolution/2.8°) and ocean (nominally 1°) general circulation models, a sea ice model, a land surface scheme, and explicit land and ocean carbon cycle models. The model features relatively coarse resolution and high throughput, which facilitates the production of large ensembles. CanESM5 has a notably higher equilibrium climate sensitivity (5.7 K) than its predecessor CanESM2 (3.8 K), which we briefly discuss, along with simulated changes over the historical period. CanESM5 simulations are contributing to the Coupled Model Intercomparison Project Phase 6 (CMIP6), and will be employed for climate science and service applications in Canada.

Download Full-text

Advancement toward coupling of the VAMPER permafrost model within the Earth system model <I>i</I>LOVECLIM (version 1.0): description and validation

Geoscientific Model Development ◽

10.5194/gmd-8-1445-2015 ◽

2015 ◽

Vol 8 (5) ◽

pp. 1445-1460 ◽

Cited By ~ 5

Author(s):

D. C. Kitover ◽

R. van Balen ◽

D. M. Roche ◽

J. Vandenberghe ◽

H. Renssen

Keyword(s):

Heat Flux ◽

Land Surface ◽

Organic Soil ◽

Earth System Model ◽

System Model ◽

Earth System ◽

Geothermal Heat ◽

Land Surface Temperatures ◽

Spatially Varying ◽

Snow Thickness

Abstract. The VU Amsterdam Permafrost (VAMPER) permafrost model has been enhanced with snow thickness and active layer calculations in preparation for coupling within the iLOVECLIM Earth system model of intermediate complexity (EMIC). In addition, maps of basal heat flux and lithology were developed within ECBilt, the atmosphere component of iLOVECLIM, so that VAMPER may use spatially varying parameters of geothermal heat flux and porosity values. The enhanced VAMPER model is validated by comparing the simulated modern-day extent of permafrost thickness with observations. To perform the simulations, the VAMPER model is forced by iLOVECLIM land surface temperatures. Results show that the simulation which did not include the snow cover option overestimated the present permafrost extent. However, when the snow component is included, the simulated permafrost extent is reduced too much. In analyzing simulated permafrost depths, it was found that most of the modeled thickness values and subsurface temperatures fall within a reasonable range of the corresponding observed values. Discrepancies between simulated and observed permafrost depth distribution are due to lack of captured effects from features such as topography and organic soil layers. In addition, some discrepancy is also due to disequilibrium with the current climate, meaning that some observed permafrost is a result of colder states and therefore cannot be reproduced accurately with constant iLOVECLIM preindustrial forcings.

Download Full-text

A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model

Geoscientific Model Development Discussions ◽

10.5194/gmdd-7-4931-2014 ◽

2014 ◽

Vol 7 (4) ◽

pp. 4931-4992

Author(s):

K. A. Crichton ◽

D. M. Roche ◽

G. Krinner ◽

J. Chappellaz

Keyword(s):

Soil Carbon ◽

Land Surface ◽

Measurement Data ◽

Grid Cell ◽

Earth System Model ◽

Carbon Pool ◽

System Model ◽

Earth System ◽

Carbon Release ◽

Surface Scheme

Abstract. We present the development and validation of a simplified permafrost-carbon mechanism for use with the land surface scheme operating in the CLIMBER-2 earth system model. The simplified model estimates the permafrost fraction of each grid cell according to the balance between modelled cold (below 0 °C) and warm (above 0 °C) days in a year. Areas diagnosed as permafrost are assigned a reduction in soil decay, thus creating a slow accumulating soil carbon pool. In warming climates, permafrost extent reduces and soil decay increases, resulting in soil carbon release to the atmosphere. Four accumulation/decay rate settings are retained for experiments within the CLIMBER-2(P) model, which are tuned to agree with estimates of total land carbon stocks today and at the last glacial maximum. The distribution of this permafrost-carbon pool is in broad agreement with measurement data for soil carbon concentration per climate condition. The level of complexity of the permafrost-carbon model is comparable to other components in the CLIMBER-2 earth system model.

Download Full-text

A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model

Geoscientific Model Development ◽

10.5194/gmd-7-3111-2014 ◽

2014 ◽

Vol 7 (6) ◽

pp. 3111-3134 ◽

Cited By ~ 6

Author(s):

K. A. Crichton ◽

D. M. Roche ◽

G. Krinner ◽

J. Chappellaz

Keyword(s):

Soil Carbon ◽

Decomposition Rate ◽

Land Surface ◽

Measurement Data ◽

Grid Cell ◽

Earth System Model ◽

Carbon Pool ◽

System Model ◽

Earth System ◽

Soil Carbon Content

Abstract. We present the development and validation of a simplified permafrost-carbon mechanism for use with the land surface scheme operating in the CLIMBER-2 earth system model. The simplified model estimates the permafrost fraction of each grid cell according to the balance between modelled cold (below 0 °C) and warm (above 0 °C) days in a year. Areas diagnosed as permafrost are assigned a reduction in soil decomposition rate, thus creating a slow accumulating soil carbon pool. In warming climates, permafrost extent reduces and soil decomposition rates increase, resulting in soil carbon release to the atmosphere. Four accumulation/decomposition rate settings are retained for experiments within the CLIMBER-2(P) model, which are tuned to agree with estimates of total land carbon stocks today and at the last glacial maximum. The distribution of this permafrost-carbon pool is in broad agreement with measurement data for soil carbon content. The level of complexity of the permafrost-carbon model is comparable to other components in the CLIMBER-2 earth system model.

Download Full-text