Keith Oleson

Keith Oleson
National Center for Atmospheric Research · Climate & Global Dynamics Laboratory

Ph.D. University of Colorado

About

110
Publications
69,084
Reads
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25,805
Citations
Additional affiliations
January 1995 - May 1998
University of Colorado Boulder
Position
  • Research Assistant
Education
January 1995 - August 1998
University of Colorado Boulder
Field of study
  • Aerospace Engineering
September 1993 - December 1994
University of Colorado Boulder
Field of study
  • Aerospace Engineering
September 1976 - May 1981
University of Colorado Boulder
Field of study
  • Aerospace Engineering

Publications

Publications (110)
Article
Prediction systems to enable Earth system predictability research on the subseasonal time scale have been developed with the Community Earth System Model, version 2 (CESM2) using two configurations that differ in their atmospheric components. One system uses the Community Atmosphere Model, version 6 (CAM6) with its top near 40 km, referred to as CE...
Article
Full-text available
Eastern China has experienced rapid urbanization during the past four decades, and it is necessary to understand the impacts of the urbanization on the regional climate. Previous simulations with either regional climate models (RCMs) or general circulation models have produced inconsistent and statistically non-significant urbanization effects on p...
Article
Full-text available
More than half of the solar energy absorbed by land surfaces is currently used to evaporate water 1. Climate change is expected to intensify the hydrological cycle 2 and to alter evapotranspiration, with implications for ecosystem services and feedback to regional and global climate. Evapotranspiration changes may already be under way, but direct o...
Article
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Urban heat waves (UHWs) are strongly associated with socioeconomic impacts. Here, we use an urban climate emulator combined with large ensemble global climate simulations to show that, at the urban scale a large proportion of the variability results from the model structural uncertainty in projecting UHWs in the coming decades under climate change....
Article
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Effective urban planning for climate-driven risks relies on robust climate projections specific to built landscapes. Such projections are absent because of a near-universal lack of urban representation in global-scale Earth system models. Here, we combine climate modelling and data-driven approaches to provide global multi-model projections of urba...
Article
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Agricultural expansion and management have greatly increased global food production and altered Earth's climate by changing physical and biogeochemical properties of terrestrial ecosystems. Few Earth system models represent agricultural management practices due to the complexity of the interactions between human decisions and biological processes o...
Preprint
Urban heat waves (UHWs) are strongly associated with socioeconomic impacts. Reliable projections of these extremes are pressingly needed for local actions in the context of extreme event preparedness and mitigation. Such information, however, is not available because current multi-model projections largely lack a representation of urban areas. Here...
Article
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Abstract The Community Land Model Urban (CLMU) is an urban parameterization developed to simulate urban climate within a global Earth System Model framework. This paper describes and evaluates parameterization and surface data improvements, and new capabilities that have been implemented since the initial release of CLMU in 2010 as part of version...
Article
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An overview of the Community Earth System Model Version 2 (CESM2) is provided, including a discussion of the challenges encountered during its development and how they were addressed. In addition, an evaluation of a pair of CESM2 long preindustrial control and historical ensemble simulations is presented. These simulations were performed using the...
Article
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The Community Land Model (CLM) is the land component of the Community Earth System Model (CESM) and is used in several global and regional modeling systems. In this paper, we introduce model developments included in CLM version 5 (CLM5), which is the default land component for CESM2. We assess an ensemble of simulations, including prescribed and pr...
Article
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The divergence among Earth system models in the terrestrial carbon cycle has prompted interest in how to reduce uncertainty. Previous studies have identified model structural uncertainty arising from process parameterizations and parameter values. The current study highlights the importance of climate forcing in generating carbon cycle uncertainty....
Article
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Land models are often used to simulate terrestrial responses to future environmental changes, but these models are not commonly evaluated with data from experimental manipulations. Results from experimental manipulations can identify and evaluate model assumptions that are consistent with appropriate ecosystem responses to future environmental chan...
Article
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Abstract Future projections of land carbon uptake in Earth System Models are affected by land surface model responses to both CO2 and nitrogen fertilization. The Community Land Model, Version 5 (CLM5), contains a suite of modifications to carbon and nitrogen cycle representation. Globally, the CLM5 has a larger CO2 response and smaller nitrogen res...
Article
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Version 5 of the Community Land Model (CLM5) introduces the plant hydraulic stress (PHS) configuration of vegetation water use, which is described and compared with the corresponding parameterization from CLM4.5. PHS updates vegetation water stress and root water uptake to better reflect plant hydraulic theory, advancing the physical basis of the m...
Technical Report
Full-text available
http://www.cesm.ucar.edu/models/cesm2/land/CLM50_Tech_Note.pdf
Article
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Land surface models used in climate models neglect the roughness sublayer and parameterize within-canopy turbulence in an ad hoc manner. We implemented a roughness sublayer turbulence parameterization in a multilayer canopy model (CLM-ml v0) to test if this theory provides a tractable parameterization extending from the ground through the canopy an...
Article
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Previous studies examining future changes in heat/cold waves using climate model ensembles have been limited to grid cell-average quantities. Here, we make use of an urban parameterization in the Community Earth System Model (CESM) that represents the urban heat island effect, which can exacerbate extreme heat but may ameliorate extreme cold in urb...
Article
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There is growing evidence that the role internal variability plays in our confidence in future climate projections has been under-appreciated in past assessments of model projections for the coming decades. In light of this, a 15 member ensemble has been produced to complement the existing 30 member “Large Ensemble” conducted with the Community Ear...
Article
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Some rare heatwaves have extreme daily mortality impacts; moderate heatwaves have lower daily impacts but occur much more frequently at present and so account for large aggregated impacts. We applied health-based models to project trends in high-mortality heatwaves, including proportion of all heatwaves expected to be high-mortality, using the defi...
Article
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Heatwaves are divided between moderate, more common heatwaves and rare “high-mortality” heatwaves that have extremely large health effects per day, which we define as heatwaves with a 20 % or higher increase in mortality risk. Better projections of the expected frequency of and exposure to these separate types of heatwaves could help communities op...
Article
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Understanding how impacts may differ across alternative levels of future climate change is necessary to inform mitigation and adaptation measures. The Benefits of Reduced Anthropogenic Climate changE (BRACE) project assesses the differences in impacts between two specific climate futures: a higher emissions future with global average temperature in...
Article
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Heat waves are among the most dangerous climate-related hazards, and they are projected to increase in frequency and intensity over the coming century. Exposure to heat waves is a function of the spatial distribution of physical events and the corresponding population distribution, and future exposure will be impacted by changes in both distributio...
Article
Full-text available
Land surface models used in climate models neglect the roughness sublayer and parameterize within-canopy turbulence in an ad hoc manner. We implemented a roughness sublayer turbulence parameterization in a multi-layer canopy model (CLM-ml v0) test if this theory provides a tractable parameterization extending from the ground through the canopy and...
Article
Full-text available
To date, existing urban land surface models (ULSMs) have been mostly evaluated and optimised for mid- and high-latitude cities. For the first time, we provide a comparative evaluation of four ULSMs for a tropical residential neighbourhood in Singapore using directly measured energy balance components. The simulations are performed offline, for an 1...
Article
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Regardless of the harmful effects of burning fossil fuels on global climate, other energy sources will become more important in the future because fossil fuels could run out by the early twenty-second century given the present rate of consumption. This implies that sooner or later humanity will rely heavily on renewable energy sources. Here we mode...
Article
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While internal climate variability is known to affect climate projections, its influence is often underappreciated and confused with model error. Why? In general, modeling centers contribute a small number of realizations to international climate model assessments (e.g., Coupled Model Intercomparison Project 5 (CMIP5)). As a result, model error and...
Article
The performance of three urban land surface models, run in offline mode, with their default external parameters, is evaluated for two distinctly different sites in Helsinki: Torni and Kumpula. The former is a dense city centre site with 22% vegetation, while the latter is a suburban site with over 50% vegetation. At both locations the models are co...
Article
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We implement and analyze 13 different metrics (4 moist thermodynamic quantities and 9 heat stress metrics) in the Community Land Model (CLM4.5), the land surface component of the Community Earth System Model (CESM). We call these routines the HumanIndexMod. These heat stress metrics embody three philosophical approaches: comfort, physiology, and em...
Article
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The Ball-Berry stomatal conductance model is commonly used in earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (g(s)) on vapor pressure deficit (D-s) and soil moisture must be empirically parameterized. We evaluated the Ball-Berry model used in the Community Land Model version...
Article
Full-text available
We implement and analyze 13 different metrics (4 moist thermodynamic quantities and 9 heat stress metrics) in the Community Land Model (CLM4.5), the land surface component of the Community Earth System Model (CESM). We call these routines the HumanIndexMod. These heat stress metrics embody three philosophical approaches: comfort, physiology, and em...
Article
Full-text available
The urban heat island (UHI), a common phenomenon in which surface temperatures are higher in urban areas than in surrounding rural areas, represents one of the most significant human-induced changes to Earth's surface climate. Even though they are localized hotspots in the landscape, UHIs have a profound impact on the lives of urban residents, who...
Article
Full-text available
The empirical Ball–Berry stomatal conductance model is commonly used in Earth system models to simulate biotic regulation of evapotranspiration. However, the dependence of stomatal conductance (gs) on vapor pressure deficit (Ds) and soil moisture must both be empirically parameterized. We evaluated the Ball–Berry model used in the Community Land Mo...
Article
Full-text available
A single-layer urban canopy model Community Land Model Urban (CLMU) is evaluated over two contrasting urban environments of Toulouse (France) and Melbourne (Australia). For the latter, three measurement sites are available characterized by a varying amount of vegetation, which supports a detailed assessment of the representation of urban vegetation...
Article
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Heat stress (HS) is a leading cause of weather-related human mortality. As temperatures continue to increase due to climate change, HS is expected to worsen. HS can be magnified in urban areas because of the urban heat island effect. We use an urban canyon model coupled to a land surface model to quantify present-day and projected mid-21st century...
Article
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The Community Land Model version 4 overestimates gross primary production (GPP) compared with estimates from FLUXNET eddy covariance towers. The revised model of Bonan et al. (2011) is consistent with FLUXNET, but values for the leaf-level photosynthetic parameter V-cmax that yield realistic GPP at the canopy-scale are lower than observed in the gl...
Article
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To assess the climate impacts of historical and projected land cover change in the Community Climate System Model, version 4 (CCSM4), new time series of transient Community Land Model, version 4 (CLM4) plant functional type (PFT) and wood harvest parameters have been developed. The new parameters capture the dynamics of the Coupled Model Intercompa...
Article
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This paper reviews developments for the Community Land Model, version 4 (CLM4), examines the land surface climate simulation of the Community Climate System Model, version 4 (CCSM4) compared to CCSM3, and assesses new earth system features of CLM4 within CCSM4. CLM4 incorporates a broad set of improvements including additions of a carbon-nitrogen (...
Article
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Urban climate models provide a useful tool for assessing the impacts of urban land surface modification on urban climates. It provides a mechanism for trialling different scenarios for urban heat island mitigation. Only recently, urban land surfaces have been included in global and regional climate models. Often they represent a trade-off between t...
Article
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Hot temperatures in combination with high humidity cause human discomfort and may increase morbidity and mortality. A global climate model with an embedded urban model is used to explore the urban-rural contrast in the wet-bulb globe temperature, a heat stress index accounting for temperature and humidity. Wet-bulb globe temperatures are calculated...
Article
Implementation of plant community dynamics into global land surface models is in a phase of rapid development. Multiple individual-, cohort- and canopy- based approaches are being deployed and, as a result, many common challenges in the representation of ecological principles in a predictive, global framework are being identifying and confronted. I...
Article
Extreme heat is a leading cause of weather-related human mortality in the United States. As global warming patterns continue, researchers anticipate increases in the severity, frequency and duration of extreme heat events, especially in the southern and western U.S. Many cities in these regions may have amplified vulnerability due to their rapidly...
Article
Full-text available
A parameterization for urban surfaces has been incorporated into the Community Land Model as part of the Community Climate System Model. The parameterization allows global simulation of the urban environment, in particular the temperature of cities and thus the urban heat island. Here, the results from climate simulations for the AR4 A2 emissions s...
Article
Full-text available
The Community Land Model version 4 (CLM4) overestimates gross primary production (GPP) compared with data-driven estimates and other process models. We use global, spatially gridded GPP and latent heat flux upscaled from the FLUXNET network of eddy covariance towers to evaluate and improve canopy processes in CLM4. We investigate differences in GPP...
Article
Full-text available
[1] The Community Land Model is the land component of the Community Climate System Model. Here, we describe a broad set of model improvements and additions that have been provided through the CLM development community to create CLM4. The model is extended with a carbon-nitrogen (CN) biogeochemical model that is prognostic with respect to vegetation...
Article
Urban land surface schemes have been developed to model the distinct features of the urban surface and the associated energy exchange processes. These models have been developed for a range of purposes and make different assumptions related to the inclusion and representation of the relevant processes. Here, the first results of Phase 2 from an int...
Article
Urban land surface schemes have been developed to model the distinct features of the urban surface and the associated energy exchange processes. These models have been developed for a range of purposes and make different assumptions related to the inclusion and representation of the relevant processes. Here, the first results of Phase 2 from an int...
Article
Terrestrial ecosystems influence climate through physical, chemical, and biological processes that affect planetary energetics, the hydrologic cycle, and atmospheric composition. Much of our understanding of how terrestrial ecosystems affect climate comes from numerical models of Earth's climate and their representation of the terrestrial biosphere...
Article
Recent studies have highlighted the need for climate models to account for urban surfaces to more realistically evaluate the impact of climate change on people in the environment where they live. In part, this is because there are significant differences in energy balance and climate between urban surfaces and the vegetated/soil (i.e., ``rural'') s...
Article
The breadth with which models of Earth’s land surface for climate simulation now represent the physics, chemistry, and biology of terrestrial ecosystems (both managed and unmanaged), the responsiveness of ecosystems to and their influence on atmospheric processes, and the pervasive influence of human activity on the biosphere (including also urbani...