scholarly journals Assessment of Snow Cover and Surface Albedo in the ECHAM5 General Circulation Model

2006 ◽  
Vol 19 (16) ◽  
pp. 3828-3843 ◽  
Author(s):  
Andreas Roesch ◽  
Erich Roeckner
Keyword(s):  
Snow Cover ◽  
Land Surface ◽  
General Circulation ◽  
Surface Albedo ◽  
Climate Model ◽  
Circulation Model ◽  
Masking Effect ◽  
Second Phase ◽  
Snow Cover Area ◽  
Highly Nonlinear

Abstract Land surface albedo, snow cover fraction (SCF), and snow depth (SD) from two versions of the ECHAM climate model are compared to available ground-based and remote-sensed climatologies. ECHAM5 accurately reproduces the annual cycle of SD and correctly captures the timing of the snowmelt. ECHAM4, in contrast, simulates an excessive Eurasian snow mass in spring due to a delayed snowmelt. Annual cycles of continental snow cover area (SCA) are captured fairly well in both ECHAM4 and ECHAM5. The negative SCA trend observed during the last two decades of the twentieth century is evident also in the ECHAM5 simulation but less pronounced. ECHAM5 captures the interannual variability of SCA reasonably well, which is in contrast with results that were reported earlier for second-phase Atmospheric Model Intercomparison Project (AMIP II) models. An error analysis revealed that, for studies on SCA, it is essential to test the data records for their homogeneity and trends. The second part of the paper compares simulated surface albedos with remote-sensed climatologies derived from PINKER and the Moderate Resolution Imaging Spectroradiometer (MODIS). ECHAM5 is in better agreement with observations in the Himalayan–Tibetan area than ECHAM4. In contrast, the positive surface albedo bias over boreal forests under snow conditions in ECHAM4 is even more pronounced in ECHAM5. This deficiency is mainly due to the neglect of the snow-masking effect of stems and branches after trees have lost their foliage. The analysis demonstrates that positive biases in the SCA are not necessarily related to positive albedo biases. Furthermore, an overestimation of the area-averaged SD is not always related to positive SCF anomalies since the relationship between SD and SCF is highly nonlinear.

scholarly journals Background albedo dynamics improve simulated precipitation variability in the Sahel region

2013 ◽  
Vol 4 (2) ◽  
pp. 595-626
Author(s):  
F. S. E. Vamborg ◽  
V. Brovkin ◽  
M. Claussen
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Surface Albedo ◽  
Rainfall Variability ◽  
Circulation Model ◽  
Dynamic Background ◽  
Simulated Precipitation ◽  
Sst Forcing ◽  
Rainfall Anomalies ◽  
Sahel Region

Abstract. Using the general circulation model ECHAM5-JSBACH forced by observed sea surface temperatures (SSTs) for the 20th century, we investigate the role of vegetation and land surface albedo dynamics in shaping rainfall variability in the Sahel. We use two different land surface albedo schemes, one in which the albedo of the canopy is varying and one in which additionally the albedo changes of the surface below the canopy are taken into account. The SST-forcing provides the background for simulating the observed decadal signal in Sahelian rainfall, though the respone to SST-forcing only is not strong enough to fully capture the observed signal. The introduction of dynamic vegetation leads to an increase in inter-annual variability of the rainfall, and gives rise to an increased number of high amplitude rainfall anomaly events. The dynamic background albedo leads to an increased persistence of the rainfall anomalies. The increase in persistence means that the difference between the dry and the wet decades is increased compared to the other simulations, and thus more closely matching the observed absolute change between these two periods. These results highlight the need for a consistent representation of land surface albedo dynamics for capturing the full extent of rainfall anomalies in the Sahel.

scholarly journals PlioMIP2 simulations using the MIROC4m climate model

2020 ◽  
Author(s):  
Wing-Le Chan ◽  
Ayako Abe-Ouchi
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
Meridional Overturning Circulation ◽  
The Arctic ◽  
Second Phase ◽  
Climate Modelling ◽  
Model Intercomparison ◽  
Model Data

Abstract. The second phase of the Pliocene Model Intercomparison Project (PlioMIP2) has attracted many climate modelling groups in its continuing efforts to better understand the climate of the mid-Piacenzian warm period (mPWP) when atmospheric CO2 was last closest to present day levels. Like the first phase, PlioMIP1, it is an internationally coordinated initiative that allows for a systematic comparison of various models in a similar manner to PMIP. Model intercomparison and model-data comparison now focus specifically on the interglacial at marine isotope stage KM5c (3.205 Ma) and experimental design is not only based on new boundary conditions but includes various sensitivity experiments. In this study, we present results from long-term model integrations using the MIROC4m atmosphere-ocean coupled general circulation model, developed at the institutes CCSR/NIES/FRCGC in Japan. The core experiment, with CO2 levels set to 400 ppm, shows a warming of 3.1 °C compared to the Pre-Industrial, with two-thirds of the warming being contributed by the increase in CO2. Although this level of warming is less than that in the equivalent PlioMIP1 experiment, there is a slightly better agreement with proxy sea surface temperature (SST) data at PRISM3 locations, especially in the northern North Atlantic where there were large model-data discrepancies in PlioMIP1. Similar changes in precipitation and sea ice are seen and the Arctic remains ice-free in the summer. However, unlike PlioMIP1, the Atlantic Meridional Overturning Circulation (AMOC) is now stronger than that of the Pre-Industrial, even though increasing CO2 tends to weaken it. This stronger AMOC is a consequence of a closed Bering Strait in the PlioMIP2 paleogeography. Also, when present day boundary conditions are replaced by those of the Pliocene, the dependency of the AMOC strength on CO2 is significantly weakened. Sensitivity tests show that lower values of CO2 give a global SST which is overall more consistent with the PRISM3 SST field presented in PlioMIP1. Inclusion of dynamical vegetation and the effects of all realistic orbital configurations should be considered in future experiments using MIROC4m for the mPWP.

scholarly journals The BRIDGE HadCM3 family of climate models: HadCM3@Bristol v1.0

2017 ◽  
Vol 10 (10) ◽  
pp. 3715-3743 ◽  
Author(s):  
Paul J. Valdes ◽  
Edward Armstrong ◽  
Marcus P. S. Badger ◽  
Catherine D. Bradshaw ◽  
Fran Bragg ◽  
...  
Keyword(s):  
Climate Change ◽  
Ocean Circulation ◽  
Land Surface ◽  
General Circulation ◽  
Computational Models ◽  
Climate Models ◽  
Climate Model ◽  
Circulation Model ◽  
Good Representation ◽  
Comprehensive Overview

Abstract. Understanding natural and anthropogenic climate change processes involves using computational models that represent the main components of the Earth system: the atmosphere, ocean, sea ice, and land surface. These models have become increasingly computationally expensive as resolution is increased and more complex process representations are included. However, to gain robust insight into how climate may respond to a given forcing, and to meaningfully quantify the associated uncertainty, it is often required to use either or both ensemble approaches and very long integrations. For this reason, more computationally efficient models can be very valuable tools. Here we provide a comprehensive overview of the suite of climate models based around the HadCM3 coupled general circulation model. This model was developed at the UK Met Office and has been heavily used during the last 15 years for a range of future (and past) climate change studies, but has now been largely superseded for many scientific studies by more recently developed models. However, it continues to be extensively used by various institutions, including the BRIDGE (Bristol Research Initiative for the Dynamic Global Environment) research group at the University of Bristol, who have made modest adaptations to the base HadCM3 model over time. These adaptations mean that the original documentation is not entirely representative, and several other relatively undocumented configurations are in use. We therefore describe the key features of a number of configurations of the HadCM3 climate model family, which together make up HadCM3@Bristol version 1.0. In order to differentiate variants that have undergone development at BRIDGE, we have introduced the letter B into the model nomenclature. We include descriptions of the atmosphere-only model (HadAM3B), the coupled model with a low-resolution ocean (HadCM3BL), the high-resolution atmosphere-only model (HadAM3BH), and the regional model (HadRM3B). These also include three versions of the land surface scheme. By comparing with observational datasets, we show that these models produce a good representation of many aspects of the climate system, including the land and sea surface temperatures, precipitation, ocean circulation, and vegetation. This evaluation, combined with the relatively fast computational speed (up to 1000 times faster than some CMIP6 models), motivates continued development and scientific use of the HadCM3B family of coupled climate models, predominantly for quantifying uncertainty and for long multi-millennial-scale simulations.

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 Background albedo dynamics improve simulated precipitation variability in the Sahel region

2014 ◽  
Vol 5 (1) ◽  
pp. 89-101 ◽  
Author(s):  
F. S. E. Vamborg ◽  
V. Brovkin ◽  
M. Claussen
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Surface Albedo ◽  
Rainfall Variability ◽  
Circulation Model ◽  
Dynamic Background ◽  
Simulated Precipitation ◽  
Sst Forcing ◽  
Rainfall Anomalies ◽  
Sahel Region

Abstract. Using the general circulation model ECHAM5–JSBACH forced by observed sea surface temperatures (SSTs) for the 20th century, we investigate the role of vegetation and land surface albedo dynamics in shaping rainfall variability in the Sahel. We use two different land surface albedo schemes, one in which the albedo of the canopy is varying and one in which the albedo changes of the surface below the canopy are also taken into account. The SST forcing provides the background for simulating the observed decadal signal in Sahelian rainfall, though the response to SST forcing only is not strong enough to fully capture the observed signal. The introduction of dynamic vegetation leads to an increase in interannual variability of the rainfall, and gives rise to an increased number of high-amplitude rainfall anomaly events. The dynamic background albedo leads to an increased persistence of the rainfall anomalies. The increase in persistence means that the difference between the dry and the wet decades is increased compared to the other simulations, and thus more closely matching the observed absolute change between these two periods. These results highlight the need for a consistent representation of land surface albedo dynamics for capturing the full extent of rainfall anomalies in the Sahel.

scholarly journals The direct radiative effect of biomass burning aerosols over southern Africa

2005 ◽  
Vol 5 (7) ◽  
pp. 1999-2018 ◽  
Author(s):  
S. J. Abel ◽  
E. J. Highwood ◽  
J. M. Haywood ◽  
M. A. Stringer
Keyword(s):  
Optical Properties ◽  
Biomass Burning ◽  
Land Surface ◽  
General Circulation ◽  
Surface Albedo ◽  
Circulation Model ◽  
Radiative Effect ◽  
Aerosol Optical Properties ◽  
African Region ◽  
Biomass Smoke

Abstract. A multi-column radiative transfer code is used to assess the direct radiative effect of biomass burning aerosols over the southern African region during September. The horizontal distribution of biomass smoke is estimated from two sources; i) General Circulation Model (GCM) simulations combined with measurements from the Aerosol Robotic Network (AERONET) of Sun photometers; ii) data from the Moderate resolution Imaging Spectrometer (MODIS) satellite. Aircraft and satellite measurements are used to constrain the cloud fields, aerosol optical properties, vertical structure, and land surface albedo included in the model. The net regional direct effect of the biomass smoke is -3.1 to -3.6 Wm-2 at the top of atmosphere, and -14.4 to -17.0 Wm-2 at the surface for the MODIS and GCM distributions of aerosol. The direct radiative effect is shown to be highly sensitive to the prescribed vertical profiles and aerosol optical properties. The diurnal cycle of clouds and the spectral dependency of surface albedo are also shown to play an important role.

scholarly journals Reproducibility of Seasonal Land Surface Climate

2006 ◽  
Vol 7 (1) ◽  
pp. 114-136 ◽  
Author(s):  
Thomas J. Phillips
Keyword(s):  
Land Surface ◽  
Seasonal Cycle ◽  
General Circulation ◽  
Climate Model ◽  
Initial Conditions ◽  
Southern Oscillation ◽  
Circulation Model ◽  
Seasonal Prediction ◽  
Climate Simulation ◽  
Continental Climate

Abstract In this study, the sensitivity of the continental seasonal climate to initial conditions is estimated from an ensemble of decadal simulations of an atmospheric general circulation model with the same specifications of radiative forcings and monthly ocean boundary conditions, but with different initial states of atmosphere and land. As measures of the “reproducibility” of continental climate for different initial conditions, spatiotemporal correlations are computed across paired realizations of 11 model land surface variables in which the seasonal cycle is either included or excluded—the former case being pertinent to climate simulation and the latter to seasonal prediction. It is found that the land surface variables that include the seasonal cycle are impacted only marginally by changes in initial conditions; moreover, their seasonal climatologies exhibit high spatial reproducibility. In contrast, the reproducibility of a seasonal land surface anomaly is generally low, although it is substantially higher in the Tropics; its spatial reproducibility also markedly fluctuates in tandem with warm and cold phases of the El Niño–Southern Oscillation. However, the overall degree of reproducibility depends on the particular land surface anomaly considered. It is also shown that the predictability of a land surface anomaly implied by its reproducibility statistics is consistent with what is inferred from more conventional predictability metrics. Implications of these results for climate model intercomparison projects and for operational forecasts of seasonal continental climate also are elaborated.

scholarly journals Multivariable evaluation of land surface processes in forced and coupled modes reveals new error sources to the simulated water cycle in the IPSL (Institute Pierre Simon Laplace) climate model

2021 ◽  
Vol 25 (4) ◽  
pp. 2199-2221
Author(s):  
Hiroki Mizuochi ◽  
Agnès Ducharne ◽  
Frédérique Cheruy ◽  
Josefine Ghattas ◽  
Amen Al-Yaari ◽  
...  
Keyword(s):  
Land Surface ◽  
General Circulation ◽  
Climate Model ◽  
Water Cycle ◽  
Circulation Model ◽  
Coupled Modes ◽  
Error Sources ◽  
Area Index ◽  
Coupled Mode ◽  
The Difference

Abstract. Evaluating land surface models (LSMs) using available observations is important for understanding the potential and limitations of current Earth system models in simulating water- and carbon-related variables. To reveal the error sources of a LSM, five essential climate variables have been evaluated in this paper (i.e., surface soil moisture, evapotranspiration, leaf area index, surface albedo, and precipitation) via simulations with the IPSL (Institute Pierre Simon Laplace) LSM ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems) model, 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 and meteorological factors (e.g., plant functional type, slope, precipitation, and irrigation) suggests potential uncertainty relating to freezing and/or snowmelt, temperate plant phenology, irrigation, and contrasted responses between forced and coupled mode simulations. The biases in the simulated variables are amplified in the 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 Assessment of soil moisture fields from imperfect climate models with uncertain satellite observations

2009 ◽  
Vol 6 (2) ◽  
pp. 2733-2750 ◽  
Author(s):  
G. Schumann ◽  
D. J. Lunt ◽  
P. J. Valdes ◽  
R. A. M. de Jeu ◽  
K. Scipal ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Surface ◽  
General Circulation ◽  
Climate Models ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Circulation Model ◽  
Data Uncertainty ◽  
Limited Area

Abstract. We demonstrate that global satellite products can be used to evaluate climate model soil moisture predictions but conclusions should be drawn with care. The quality of a limited area climate model (LAM) was compared to a general circulation model (GCM) using soil moisture data from two different Earth observing satellites within a model validation scheme that copes with the presence of uncertain data. Results showed that in the face of imperfect models and data, it is difficult to investigate the quality of current land surface schemes in simulating hydrology accurately. Nevertheless, a LAM provides, in general, a better representation of spatial patterns and dynamics of soil moisture. However, in months when data uncertainty is higher, particularly in colder months and in periods when vegetation cover and soil moisture are out of phase (e.g. August in the case of Western Europe), it is not possible to draw firm conclusions about model acceptability. Our work indicates that a higher resolution LAM has more benefits to soil moisture prediction than are due to the resolution alone and can be attributed to an overall intensification of the hydrological cycle relative to the GCM.

scholarly journals The BRIDGE HadCM3 family of climate models: HadCM3@Bristol v1.0

2017 ◽  
Author(s):  
Paul J. Valdes ◽  
Edward Armstrong ◽  
Marcus P. S. Badger ◽  
Catherine D. Bradshaw ◽  
Fran Bragg ◽  
...  
Keyword(s):  
Climate Change ◽  
Ocean Circulation ◽  
Land Surface ◽  
General Circulation ◽  
Computational Models ◽  
Climate Models ◽  
Climate Model ◽  
Coupled Model ◽  
Circulation Model ◽  
Good Representation

Abstract. Understanding natural and anthropogenic climate change processes involves using computational models that represent the main components of the Earth system: the atmosphere, ocean, sea-ice and land surface. These models have become increasingly computationally expensive as resolution is increased and more complex process representations are included. However, to gain robust insight into how climate may respond to a given forcing, and to meaningfully quantify the associated uncertainty, it is often required to use either or both of ensemble approaches and very long integrations. For this reason, more computationally efficient models can be very valuable tools. Here we provide a comprehensive overview of the suite of climate models based around the coupled general circulation model HadCM3. This model was originally developed at the UK Met Office and has been heavily used during the last 15 years for a range of future (and past) climate change studies but is now largely being replaced by more recent models. However, it continues to be extensively used by the BRIDGE (Bristol Research Initiative for the Dynamic Global Environment) research group at the University of Bristol and elsewhere. Over time, adaptations have been made to the base HadCM3 model. These adaptations mean that the original documentation is not entirely representative, and several other configurations are in use which now differ from the originally described model versions. We therefore describe the key features of a number of configurations of the HadCM3 climate model family, including the atmosphere-only model (HadAM3), the coupled model with a low resolution ocean (HadCM3L), the high resolution atmosphere only model (HadAM3H), the regional model (HadRM3) and a fast coupled model (FAMOUS), which together make up HadCM3@Bristol version 1.0. These also include three versions of the land surface scheme. By comparing with observational datasets, we show that these models produce a good representation of many aspects of the climate system, including the land and sea surface temperatures, precipitation, ocean circulation and vegetation. This evaluation, combined with the relatively fast computational speed (up to 2000× faster than some CMIP6 models), motivates continued development and scientific use of the HadCM3 family of coupled climate models, particularly for quantifying uncertainty and for long multi-millennial scale simulations.

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