scholarly journals Radiative–Convective Equilibrium over a Land Surface

2014 ◽  
Vol 27 (23) ◽  
pp. 8611-8629 ◽  
Author(s):  
Nicolas Rochetin ◽  
Benjamin R. Lintner ◽  
Kirsten L. Findell ◽  
Adam H. Sobel ◽  
Pierre Gentine
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Multiple Equilibria ◽  
Circulation Model ◽  
Internal Variability ◽  
Necessary Condition ◽  
Surface Model ◽  
Total System ◽  
Vertical Temperature Profile ◽  
Surface Precipitation

Abstract Radiative–convective equilibrium (RCE) describes an idealized state of the atmosphere in which the vertical temperature profile is determined by a balance between radiative and convective fluxes. While RCE has been applied extensively over oceans, its application over the land surface has been limited. The present study explores the properties of RCE over land using an atmospheric single-column model (SCM) from the Laboratoire de Météorologie Dynamique–Zoom, version 5B (LMDZ5B) general circulation model coupled in temperature and moisture to a land surface model using a simplified bucket model with finite moisture capacity. Given the presence of a large-amplitude diurnal heat flux cycle, the resultant RCE exhibits multiple equilibria when conditions are neither strictly water nor energy limited. By varying top-of-atmosphere insolation (through changes in latitude), total system water content, and initial temperature conditions the sensitivity of the land RCE states is assessed, with particular emphasis on the role of clouds. Based on this analysis, it appears that a necessary condition for the model to exhibit multiple equilibria is the presence of low-level clouds coupled to the diurnal cycle of radiation. In addition the simulated surface precipitation rate varies nonmonotonically with latitude as a result of a tradeoff between in-cloud rain rate and subcloud rain reevaporation, thus underscoring the importance of subcloud layer processes and unsaturated downdrafts. It is shown that clouds, especially at low levels, are key elements of the internal variability of the coupled land–atmosphere system through their feedback on radiation.

scholarly journals TransEBM v. 1.0: description, tuning, and validation of a transient model of the Earth's energy balance in two dimensions

2021 ◽  
Vol 14 (5) ◽  
pp. 2843-2866
Author(s):  
Elisa Ziegler ◽  
Kira Rehfeld
Keyword(s):  
Energy Balance ◽  
Land Surface ◽  
General Circulation ◽  
Circulation Model ◽  
Internal Variability ◽  
Two Dimensions ◽  
Balance Model ◽  
Seasonal Temperature ◽  
Transient Model

Abstract. Modeling the long-term transient evolution of climate remains a technical and scientific challenge. However, understanding and improving modeling of the long-term behavior of the climate system increases confidence in projected changes in the mid- to long-term future. Energy balance models (EBMs) provide simplified and computationally efficient descriptions of long timescales and allow large ensemble runs by parameterizing energy fluxes. In this way, they can be used to pinpoint periods and phenomena of interest. Here, we present TransEBM, an extended version of the two-dimensional energy balance model by Zhuang et al. (2017a). Transient CO2, solar insolation, orbital configuration, fixed ice coverage, and land–sea distribution are implemented as effective radiative forcings at the land surface. We show that the model is most sensitive to changes in CO2 and ice distribution, but the obliquity and land–sea mask have significant influence on modeled temperatures as well. We tune TransEBM to reproduce the 1960–1989 CE global mean temperature and the Equator-to-pole and seasonal temperature gradients of ERA-20CM reanalysis (Hersbach et al., 2015). The resulting latitudinal and seasonal temperature distributions agree well with reanalysis and the general circulation model (GCM) HadCM3 for a simulation of the past millennium (Bühler et al., 2020). TransEBM does not represent the internal variability of the ocean–atmosphere system, but non-deterministic elements and nonlinearity can be introduced through model restarts and randomized forcing. As the model facilitates long transient simulations, we envisage its use in exploratory studies of stochastic forcing and perturbed parameterizations, thus complementing studies with comprehensive GCMs.

scholarly journals Effect of Human-Induced Land Disturbance on Subseasonal Predictability of Near-Surface Variables Using an Atmospheric General Circulation Model

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 725
Author(s):  
Tomohito J. Yamada ◽  
Yadu Pokhrel
Keyword(s):  
General Circulation Model ◽  
Land Surface ◽  
General Circulation ◽  
Atmospheric General Circulation Model ◽  
Circulation Model ◽  
Weather Forecast ◽  
Surface Model ◽  
Near Surface ◽  
Land Disturbance ◽  
Atmospheric General Circulation

Irrigation can affect climate and weather patterns from regional to global scales through the alteration of surface water and energy balances. Here, we couple a land-surface model (LSM) that includes various human land-water management activities including irrigation with an atmospheric general circulation model (AGCM) to examine the impacts of irrigation-induced land disturbance on the subseasonal predictability of near-surface variables. Results indicate that the simulated global irrigation and groundwater withdrawals (circa 2000) are ~3600 and ~370 km3/year, respectively, which are in good agreement with previous estimates from country statistics and offline–LSMs. Subseasonal predictions for boreal summers during the 1986–1995 period suggest that the spread among ensemble simulations of air temperature can be substantially reduced by using realistic land initializations considering irrigation-induced changes in soil moisture. Additionally, it is found that the subseasonal forecast skill for near-surface temperature and sea level pressure significantly improves when human-induced land disturbance is accounted for in the AGCM. These results underscore the need to incorporate irrigation into weather forecast models, such as the global forecast system.

scholarly journals Multi-variable evaluation of land surface processes in forced and coupled modes reveals new error sources to the simulated water cycle in the IPSL climate model

2020 ◽  
Author(s):  
Hiroki Mizuochi ◽  
Agnes Ducharne ◽  
Frédérique Cheruy ◽  
Josefine Ghattas ◽  
Amen Al-Yaari ◽  
...  
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Climate Model ◽  
Water Cycle ◽  
Circulation Model ◽  
Surface Model ◽  
Coupled Modes ◽  
Error Sources ◽  
Area Index ◽  
Coupled Mode

Abstract. Evaluating land surface models (LSMs) using available observations is important to understand the potential and limitations of current Earth system models in simulating water- and carbon-related variables. To reveal the error sources of a land surface model (LSM), four essential climate variables have been evaluated in this paper (i.e., surface soil moisture, evapotranspiration, leaf area index, and surface albedo) via simulations with IPSL LSM ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems), particularly focusing on the difference between (i) forced simulations with atmospheric forcing data (WATCH-Forcing-DATA-ERA-Interim: WFDEI) and (ii) coupled simulations with the IPSL atmospheric general circulation model. Results from statistical evaluation using satellite- and ground-based reference data show that ORCHIDEE is well equipped to represent spatiotemporal patterns of all variables in general. However, further analysis against various landscape/meteorological factors (e.g., plant functional type, slope, precipitation, and irrigation) suggests potential uncertainty relating to freezing/snowmelt, temperate plant phenology, irrigation, as well as contrasted responses between forced and coupled mode simulations. The biases in the simulated variables are amplified in coupled mode via surface–atmosphere interactions, indicating a strong link between irrigation–precipitation and a relatively complex link between precipitation–evapotranspiration that reflects the hydrometeorological regime of the region (energy-limited or water-limited) and snow-albedo feedback in mountainous and boreal regions. The different results between forced and coupled modes imply the importance of model evaluation under both modes to isolate potential sources of uncertainty in the model.

scholarly journals On the impact of recent developments of the LMDz atmospheric general circulation model on the simulation of CO<sub>2</sub> transport

2018 ◽  
Vol 11 (11) ◽  
pp. 4489-4513 ◽  
Author(s):  
Marine Remaud ◽  
Frédéric Chevallier ◽  
Anne Cozic ◽  
Xin Lin ◽  
Philippe Bousquet
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Circulation Model ◽  
Surface Model ◽  
Strong Impact ◽  
Vertical Resolution ◽  
Atmospheric General Circulation ◽  
Inverse Systems ◽  
The Impact ◽  
Physical Parameterizations

Abstract. The quality of the representation of greenhouse gas (GHG) transport in atmospheric general circulation models (GCMs) drives the potential of inverse systems to retrieve GHG surface fluxes to a large extent. In this work, the transport of CO2 is evaluated in the latest version of the Laboratoire de Météorologie Dynamique (LMDz) GCM, developed for the Climate Model Intercomparison Project 6 (CMIP6) relative to the LMDz version developed for CMIP5. Several key changes have been implemented between the two versions, which include a more elaborate radiative scheme, new subgrid-scale parameterizations of convective and boundary layer processes and a refined vertical resolution. We performed a set of simulations of LMDz with different physical parameterizations, two different horizontal resolutions and different land surface schemes, in order to test the impact of those different configurations on the overall transport simulation. By modulating the intensity of vertical mixing, the physical parameterizations control the interhemispheric gradient and the amplitude of the seasonal cycle in the Northern Hemisphere, as emphasized by the comparison with observations at surface sites. However, the effect of the new parameterizations depends on the region considered, with a strong impact over South America (Brazil, Amazonian forest) but a smaller impact over Europe, East Asia and North America. A finer horizontal resolution reduces the representation errors at observation sites near emission hotspots or along the coastlines. In comparison, the sensitivities to the land surface model and to the increased vertical resolution are marginal.

scholarly journals On the impact of recent developments of an atmospheric general circulation model on the simulation of CO<sub>2</sub> transport

2018 ◽  
Author(s):  
Marine Remaud ◽  
Frédéric Chevallier ◽  
Anne Cozic ◽  
Xin Lin ◽  
Philippe Bousquet
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Circulation Model ◽  
Surface Model ◽  
Strong Impact ◽  
Vertical Resolution ◽  
Atmospheric General Circulation ◽  
Inverse Systems ◽  
The Impact ◽  
Physical Parameterizations

Abstract. The quality of the representation of greenhouse gas (GHG) transport in atmospheric General Circulation Models (GCMs) drives the potential of inverse systems to retrieve GHG surface fluxes to a large extent. In this work, the transport of CO2 is evaluated in the latest version of the LMDz GCM, developed for the Climate Model Intercomparison Project 6 (CMIP6) relative to the LMDz version developed for CMIP4. Several key changes have been implemented between the two versions; those include a more elaborate radiative scheme, new sub-grid scale parameterizations of convective and boundary layer processes, and a refined vertical resolution. We performed a set of simulations of LMDz with the different physical parameterizations, two different horizontal resolutions and different land surface schemes, in order to test the impact of those different configurations on the overall transport simulation. By modulating the intensity of vertical mixing, the physical parameterizations control the interhemispheric gradient and the amplitude of the seasonal cycle in the summer northern hemisphere, as emphasized by the comparison with observations at surface sites. However, the effect of the new parameterizations depends on the region considered, with a strong impact over South America (Brazil, Amazonian forest) but a smaller impact over Europe, Eastern Asia and North America. A finer horizontal resolution reduces the representation errors at observation sites near emission-hot spots or along the coastlines. In comparison, the sensitivities to the land surface model and to the increased vertical resolution are marginal.

scholarly journals A comprehensive set of benchmark tests for a land surface model of simultaneous fluxes of water and carbon at both the global and seasonal scale

2011 ◽  
Vol 4 (2) ◽  
pp. 255-269 ◽  
Author(s):  
E. Blyth ◽  
D. B. Clark ◽  
R. Ellis ◽  
C. Huntingford ◽  
S. Los ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Land Surface ◽  
General Circulation ◽  
River Flow ◽  
Land Surface Model ◽  
Circulation Model ◽  
Global Network ◽  
Surface Model ◽  
Model Errors ◽  
Benchmark Tests

Abstract. Evaluating the models we use in prediction is important as it allows us to identify uncertainties in prediction as well as guiding the priorities for model development. This paper describes a set of benchmark tests that is designed to quantify the performance of the land surface model that is used in the UK Hadley Centre General Circulation Model (JULES: Joint UK Land Environment Simulator). The tests are designed to assess the ability of the model to reproduce the observed fluxes of water and carbon at the global and regional spatial scale, and on a seasonal basis. Five datasets are used to test the model: water and carbon dioxide fluxes from ten FLUXNET sites covering the major global biomes, atmospheric carbon dioxide concentrations at four representative stations from the global network, river flow from seven catchments, the seasonal mean NDVI over the seven catchments and the potential land cover of the globe (after the estimated anthropogenic changes have been removed). The model is run in various configurations and results are compared with the data. A few examples are chosen to demonstrate the importance of using combined use of observations of carbon and water fluxes in essential in order to understand the causes of model errors. The benchmarking approach is suitable for application to other global models.

scholarly journals A comprehensive set of benchmark tests for a land surface model of simultaneous fluxes of water and carbon at both the global and seasonal scale

2010 ◽  
Vol 3 (4) ◽  
pp. 1829-1859 ◽  
Author(s):  
E. Blyth ◽  
D. B. Clark ◽  
R. Ellis ◽  
C. Huntingford ◽  
S. Los ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Land Surface ◽  
General Circulation ◽  
River Flow ◽  
Land Surface Model ◽  
Circulation Model ◽  
Global Network ◽  
Surface Model ◽  
Model Errors ◽  
Benchmark Tests

Abstract. This paper describes a set of benchmark tests that is designed to quantify the performance of the land surface model that is used in the UK Hadley Centre General Circulation Model (JULES: Joint UK Land Environment Simulator). The tests are designed to assess the ability of the model to reproduce the observed fluxes of water and carbon at the global and regional spatial scale, and on a seasonal basis. Five datasets are used to test the model: water and carbon dioxide fluxes from ten FLUXNET sites covering the major global biomes, atmospheric carbon dioxide concentrations at four representative stations from the global network, river flow from seven catchments, the seasonal mean NDVI over the seven catchments and the potential land cover of the globe (after the estimated anthropogenic changes have been removed). The model is run in various configurations and results are compared with the data. The results show that combined use of observations of carbon and water fluxes is essential in order to understand the causes of model errors. The benchmarking approach is suitable for application to other global models.

scholarly journals Biases in Reanalysis Snowfall Found by Comparing the JULES Land Surface Model to GlobSnow

2014 ◽  
Vol 27 (2) ◽  
pp. 624-632 ◽  
Author(s):  
Steven Hancock ◽  
Brian Huntley ◽  
Richard Ellis ◽  
Robert Baxter
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Snow Water Equivalent ◽  
European Space Agency ◽  
Land Surface Model ◽  
Circulation Model ◽  
Reanalysis Data ◽  
Climatic Research Unit ◽  
Surface Model ◽  
Gauge Data

Abstract Snow exerts a strong influence on weather and climate. Accurate representation of snow processes within models is needed to ensure accurate predictions. Snow processes are known to be a weakness of land surface models (LSMs), and studies suggest that more complex snow physics is needed to avoid early melt. In this study the European Space Agency (ESA)’s Global Snow Monitoring for Climate Research (GlobSnow) snow water equivalent and NASA’s “MOD10C1” snow cover products are used to assess the accuracy of snow processes within the Joint U.K. Land Environment Simulator (JULES). JULES is run “offline” from a general circulation model and so is driven by meteorological reanalysis datasets: “Princeton,” Water and Global Change–Global Precipitation Climatology Centre (WATCH–GPCC), and WATCH–Climatic Research Unit (CRU). This reveals that when the model achieves the correct peak accumulation, snow does not melt early. However, generally snow does melt early because peak accumulation is too low. Examination of the meteorological reanalysis data shows that not enough snow falls to achieve observed peak accumulations. Thus, the earlier studies’ conclusions may be as a result of weaknesses in the driving data, rather than in model snow processes. These reanalysis products “bias correct” precipitation using observed gauge data with an undercatch correction, overriding the benefit of any other datasets used in their creation. This paper argues that using gauge data to bias-correct reanalysis data is not appropriate for snow-affected regions during winter and can lead to confusion when evaluating model processes.

scholarly journals The Flexible Ocean and Climate Infrastructure version 1 (FOCI1): mean state and variability

2020 ◽  
Vol 13 (6) ◽  
pp. 2533-2568 ◽  
Author(s):  
Katja Matthes ◽  
Arne Biastoch ◽  
Sebastian Wahl ◽  
Jan Harlaß ◽  
Torge Martin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Land Surface ◽  
General Circulation ◽  
Climate Models ◽  
Weather Prediction ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
Climate System ◽  
Surface Model ◽  
Model Components

Abstract. A new Earth system model, the Flexible Ocean and Climate Infrastructure (FOCI), is introduced. A first version of FOCI consists of a global high-top atmosphere (European Centre Hamburg general circulation model; ECHAM6.3) and an ocean model (Nucleus for European Modelling of the Ocean v3.6; NEMO3.6) as well as sea-ice (Louvain-la-Neuve sea Ice Model version 2; LIM2) and land surface model components (Jena Scheme for Biosphere Atmosphere Coupling in Hamburg; JSBACH), which are coupled through the OASIS3-MCT software package. FOCI includes a number of optional modules which can be activated depending on the scientific question of interest. In the atmosphere, interactive stratospheric chemistry can be used (ECHAM6-HAMMOZ) to study, for example, the effects of the ozone hole on the climate system. In the ocean, a biogeochemistry model (Model of Oceanic Pelagic Stoichiometry; MOPS) is available to study the global carbon cycle. A unique feature of FOCI is the ability to explicitly resolve mesoscale ocean eddies in specific regions. This is realized in the ocean through nesting; first examples for the Agulhas Current and the Gulf Stream systems are described here. FOCI therefore bridges the gap between coarse-resolution climate models and global high-resolution weather prediction and ocean-only models. It allows to study the evolution of the climate system on regional and seasonal to (multi)decadal scales. The development of FOCI resulted from a combination of the long-standing expertise in ocean and climate modeling in several research units and divisions at the Helmholtz Centre for Ocean Research Kiel (GEOMAR). FOCI will thus be used to complement and interpret long-term observations in the Atlantic, enhance the process understanding of the role of mesoscale oceanic eddies for large-scale oceanic and atmospheric circulation patterns, study feedback mechanisms with stratospheric processes, estimate future ocean acidification, and improve the simulation of the Atlantic Meridional Overturning Circulation changes and their influence on climate, ocean chemistry and biology. In this paper, we present both the scientific vision for the development of FOCI as well as some technical details. This includes a first validation of the different model components using several configurations of FOCI. Results show that the model in its basic configuration runs stably under pre-industrial control as well as under historical forcing and produces a mean climate and variability which compares well with observations, reanalysis products and other climate models. The nested configurations reduce some long-standing biases in climate models and are an important step forward to include the atmospheric response in multidecadal eddy-rich configurations.

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