Plant functional type classification for Earth System Models: results from the European Space Agency's Land Cover Climate Change Initiative
Summary: Land cover is an essential variable in earth system models and determines conditions driving biogeochemical, energy, and water exchange between ecosystems and the atmosphere. A methodology is presented for mapping plant functional types used in global vegetation models from a updated land cover classification system and open-source conversion tool, resulting from a consultative process among map producers and modelers engaged in the European Space Agency’s Land Cover Climate Change Initiative.
B. Poulter, N. MacBean, A. Hartley, I. Khlystova, O. Arino, R. Betts, S. Bontemps, M. Boettcher, C. Brockmann, P. Defourny, S. Hagemann, M. Herold, G. Kirches, C. Lamarche, D. Lederer, C. Ottlé, M. Peters, and P. Peylin Geosci. Model Dev. Discuss., 8, 429-462, 2015 AbstractDiscussion Paper (PDF, 2172 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for GMD
21 Jan 2015
The integrated Earth System Model (iESM): formulation and functionality
Summary: The integrated Earth System Model (iESM) has been developed as a
new tool for projecting the joint human/climate system. The
iESM is based upon coupling an Integrated assessment model (IAM)
and an Earth system model (ESM) into a common modeling
infrastructure. By introducing heretofore-omitted
feedbacks between natural and societal drivers in iESM, we can improve
scientific understanding of the human-Earth system
W. D. Collins, A. P. Craig, J. E. Truesdale, A. V. Di Vittorio, A. D. Jones, B. Bond-Lamberty, K. V. Calvin, J. A. Edmonds, S. H. Kim, A. M. Thomson, P. Patel, Y. Zhou, J. Mao, X. Shi, P. E. Thornton, L. P. Chini, and G. C. Hurtt Geosci. Model Dev. Discuss., 8, 381-427, 2015 AbstractDiscussion Paper (PDF, 1447 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for GMD
21 Jan 2015
The software architecture of climate models: a graphical comparison of CMIP5 and EMICAR5 configurations
Summary: This paper describes an analysis of the software architecture of global climate models. The analysis provides a visualization of structure of these models, and reveals interesting differences between the models developed at different research labs.
ESP v2.0: enhanced method for exploring emission impacts of future scenarios in the United States – addressing spatial allocation
Summary: We present and demonstrate Version 2.0 of the Emission Scenario Projection (ESP) method. This method produces multi-decadal air pollutant emission projections suitable for air quality modeling. The method focuses on energy-related emissions, including those from the electric sector, buildings, industry and transportation. ESP v2.0 enhances ESP v1.0 by taking into population growth and migration and land use change into consideration.
A two-layer canopy with thermal inertia for an improved modelling of the sub-canopy snowpack energy-balance
Summary: We improve the canopy module of a very detailed snow model, Snowpack, with a view of a more consistant representation of the sub-canopy energy balance, of interest for the snowpack.
We show that adding a formulation of (i) the canopy heat capacity and (ii) a lowermost canopy layer (alike trunk + solar shaded leaves) yields significant improvement in the representation of sub-canopy incoming longwave radiations, especially at nighttime. This energy is a contributor to snowmelt.
CH4 parameter estimation in CLM4.5bgc using surrogate global optimization
Summary: We tune the CH4-related parameters of the Community Land Model (CLM) using surrogate global optimization in order to reduce the discrepancies between the CLM predictions and observed CH4 emissions. This is the first application of a surrogate optimization method to calibrate a global climate model. We found that the observation data drives the model to predict more CH4 emissions in the northern latitudes and less in the tropics.
J. Müller, R. Paudel, C. A. Shoemaker, J. Woodbury, Y. Wang, and N. Mahowald Geosci. Model Dev. Discuss., 8, 141-207, 2015 AbstractDiscussion Paper (PDF, 4264 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for GMD
06 Jan 2015
EMPOWER-1.0: an Efficient Model of Planktonic ecOsystems WrittEn in R
Summary: Ecosystem models provide a powerful tool for simulating ocean biology. Care must be exercised when selecting appropriate equations and parameter values to represent chosen marine ecosystems. Here, we present an efficient plankton model testbed, using simplified physics and coded in the freely available language R. Multiple runs can be undertaken for different ocean sites, permitting thorough evaluation of ecosystem model performance. The testbed also serves as an excellent resource for teaching.
A high-resolution ocean and sea-ice modelling system for the Arctic and North Atlantic Oceans
Summary: 1/12th degree resolution runs of Arctic-Atlantic were compared for the period 2003-2009. We found:
-accurate representation of sea surface height and of its statistics.
-model temperature and salinity in general agreement with in-situ measurements, but upper ocean properties in Beaufort Sea are challenging.
-distribution of concentration and volume of sea ice is improved when slowing down the ice.
-further improvements require better initial conditions and modifications to mixing.
Accelerating the spin-up of the coupled carbon and nitrogen cycle model in CLM4
Summary: 1. A gradient projection method was used to reduce the computation time of carbon/nitrogen spin-up process in CLM4.
2. Point scale simulations showed that the cyclic stability of total carbon for some cases differs from that of the periodic atmospheric forcing, and some cases even showed instability.
3. The instability issue is resolved after the hydrology scheme in CLM4 is replaced with a flow model for variably saturated porous media.
Path-integral method for the source apportionment of photochemical pollutants
Summary: A new method is presented for allocating the anthropogenic part of a pollutant concentration to the sources responsible. The method requires integrating sensitivity coefficients over a range of emissions defined by an emission-control strategy. A simplified photochemical model is used to evaluate options for the numerical integration and the dependence of the source contributions on the control strategy. Results are presented for ozone, formaldehyde, nitrogen dioxide, and nitric acid.
On the wind stress formulation over shallow waters in atmospheric models
Summary: In spite of the substantial observational evidence supporting a higher drag over shallow waters than over the open ocean, regional and global models widely use a single formulation valid for the open ocean. Results of this work indicate that adding the extra drag is necessary to reconcile model results with long term observations of the wind profile within the first 100 m of the atmosphere, being the first modeling evidence supporting the reported added drag over shallow waters.
Modelling the role of fires in the terrestrial carbon balance by incorporating SPITFIRE into the global vegetation model ORCHIDEE – Part 2: Carbon emissions and the role of fires in the global carbon balance
Summary: We conducted parallel simulations using a global land surface model, with and without fires being included, respectively. When the anthropogenic land cover change fire is excluded, we find that natural wildfires have reduced the global land carbon uptake by 0.3 Pg C per year over the 1901-2012. This is equivalent to 20% of the land carbon uptake in a world without fire. This fire-induced reduction in carbon uptake could be partly explained by climate variability, in particular the ENSO events.
Description and evaluation of tropospheric chemistry and aerosols in the Community Earth System Model (CESM1.2)
Summary: The Community Atmosphere Model (CAM), version 5, is now coupled to extensive tropospheric and stratospheric chemistry, called CAM5-chem, and is available in addition to CAM4-chem in the Community Earth System Model (CESM) version 1.2. Both configurations are well suited as tools for atmospheric chemistry modeling studies in the troposphere and lower stratosphere.
S. Tilmes, J.-F. Lamarque, L. K. Emmons, D. E. Kinnison, P.-L. Ma, X. Liu, S. Ghan, C. Bardeen, S. Arnold, M. Deeter, F. Vitt, T. Ryerson, J. W. Elkins, F. Moore, and R. Spackman Geosci. Model Dev. Discuss., 7, 8875-8940, 2014 AbstractDiscussion Paper (PDF, 8374 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMD
12 Dec 2014
Normal-mode function representation of global 3-D datasets: an open-access software for atmospheric research community
The terminator "toy"-chemistry test: a simple tool to assess errors in transport schemes
Summary: This test extends the evaluation of transport schemes from prescribed advection of inert scalars to reactive species. It consists of transporting two reacting chlorine-like species in an idealized flow field, The sources/sinks are given by a simple, but non-linear, `toy' chemistry that mimics photolysis-driven processes near the solar terminator. As a result, strong gradients in the spatial distribution of the species develop near the edge of the terminator.
Forecast error covariance structure in coupled atmosphere–chemistry data assimilation
Summary: The structure of an ensemble-based coupled atmosphere-chemistry forecast error covariance is examined using the WRF-Chem, a coupled atmosphere-chemistry model. It is found that the coupled error covariance has important cross-variable components that allow a physically meaningful adjustment of all control variables. Additional benefit of the coupled error covariance is that a cross-component impact is allowed, e.g., atmospheric observations can exert impact on chemistry analysis, and vice versa.
Modelling atmospheric dry deposition in urban areas using an urban canopy approach
Summary: Atmospheric dry deposition is classically modelled using an average roughness
length. This approach cannot account for the spatial variability of dry deposition in urban areas. We extend here the urban canyon concept, previously introduced to parametrise momentum and heat transfer, to mass transfer. This approach provides spatially-distributed dry deposition fluxes that depend on surfaces (streets, walls, roofs) and flow regimes (recirculation and ventilation) within the urban area.
A multi-layer land surface energy budget model for implicit coupling with global atmospheric simulations
J. Ryder, J. Polcher, P. Peylin, C. Ottlé, Y. Chen, E. van Gorsel, V. Haverd, M. J. McGrath, K. Naudts, J. Otto, A. Valade, and S. Luyssaert Geosci. Model Dev. Discuss., 7, 8649-8701, 2014 AbstractDiscussion Paper (PDF, 2998 KB)Supplement (1696 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for GMD
08 Dec 2014
A vertically discretised canopy description for ORCHIDEE (SVN r2290) and the modifications to the energy, water and carbon fluxes
Summary: Despite the potential of forest management to mitigate climate change, none of today's predictions of future climate account for the impact of forest management. To address this gap in modelling capability we developed and parametrized a land surface model to simulate biogeochemical and biophysical effects of forest management. Comparison of model output against data showed an increased model performance in reproducing large-scale spatial patterns and inter-annual variability over Europe.
K. Naudts, J. Ryder, M. J. McGrath, J. Otto, Y. Chen, A. Valade, V. Bellasen, G. Berhongaray, G. Bönisch, M. Campioli, J. Ghattas, T. De Groote, V. Haverd, J. Kattge, N. MacBean, F. Maignan, P. Merilä, J. Penuelas, P. Peylin, B. Pinty, H. Pretzsch, E. D. Schulze, D. Solyga, N. Vuichard, Y. Yan, and S. Luyssaert Geosci. Model Dev. Discuss., 7, 8565-8647, 2014 AbstractDiscussion Paper (PDF, 1482 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for GMD
05 Dec 2014
A dynamic marine iron cycle module coupled to the University of Victoria Earth System Model: the Kiel Marine Biogeochemical Model 2 (KMBM2) for UVic 2.9
Summary: In this paper we find that including the marine cycle of the phytoplankton nutrient iron in a global climate model improves the agreement between observed and simulated nutrient concentrations in the ocean and that a better description of the source of iron from the sediment to the ocean is more important than of iron-containing dust deposition. Finally, we find that the response of the iron cycle to climate warming affects the phytoplankton growth and nutrient cycles.
Twelve-month, 12 km resolution North American WRF-Chem v3.4 air quality simulation: performance evaluation
Summary: We evaluate the predictive performance of a 12-month, 12-km horizontal resolution WRF-Chem air quality model simulation for the contiguous United States. Model performance is comparable to other contemporary models used for regulatory and health-effects analysis, with 12% bias for daytime ozone and -1% bias for fine particulate matter (PM2.5). Performance for PM2.5 is worse in winter and in the western U.S. than in other seasons and regions, suggesting opportunities for future model development.
Tuning and assessment of the HYCOM-NORWECOM V2.1 modeling system
Summary: Biogeochemical models are increasingly used in forecasting systems. They provide parameter fields such as nutrients, chlorophyll and oxygen for scientific use and for marine management. This paper describes a model currently used for forecasting the North Atlantic and Arctic on a weekly basis and the evaluation of this model against observations. The model provides reliable fields of nutrients, while the predicted phytoplankton fields are still connected
til large uncertainties.
Development of efficient GPU parallelization of WRF Yonsei University planetary boundary layer scheme
Summary: To expedite weather research and prediction, we have put tremendous effort into developing an accelerated implementation of the entire WRF model using GPU massive parallel computing architecture. This paper presents our efficient GPU-based design on WRF YSU PBL scheme. Using one NVIDIA Tesla K40 GPU, the GPU-based YSU PBL scheme achieves a speedup of 193x with respect to its runtime on one CPU core. We can even boost the speedup to 360x with respect to one CPU core as two K40 GPUs are applied.
M. Huang, J. Mielikainen, B. Huang, H. Chen, H.-L. A. Huang, and M. D. Goldberg Geosci. Model Dev. Discuss., 7, 8031-8077, 2014 AbstractDiscussion Paper (PDF, 2612 KB)Interactive Discussion (Open, 0 Comments)Manuscript under review for GMD
21 Nov 2014
Modelling climate change responses in tropical forests: similar productivity estimates across five models, but different mechanisms and responses
Summary: This study evaluates the capability of five vegetation models to simulate the response of forest productivity to changes in temperature and drought, using data collected from an Amazonian forest. This study concludes that model consistencies in the responses of net canopy carbon production to temperature and precipitation change were the result of inconsistent modelled leaf scale process responses and substantial variation in modelled leaf area responses.
L. Rowland, A. Harper, B. O. Christoffersen, D. R. Galbraith, H. M. A. Imbuzeiro, T. L. Powell, C. Doughty, N. M. Levine, Y. Malhi, S. R. Saleska, P. R. Moorcroft, P. Meir, and M. Williams Geosci. Model Dev. Discuss., 7, 7823-7859, 2014 AbstractDiscussion Paper (PDF, 1556 KB)Supplement (1042 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMD
19 Nov 2014
Verifications of the nonlinear numerical model and polarization relations of atmospheric acoustic-gravity waves
Summary: We performed high-resolution numerical simulations of nonlinear acoustic-gravity waves (AGWs) at altitudes 0 – 500 km and compared them with analytical polarization relations of linear AGW theory. After some transition time, t > te, the numbers of numerically simulated and analytical pairs of AGW parameters, which are equal with confidence 95%, are larger at altitudes 30 - 60 km and are smaller at t < te. The differences reveal circumstances, when numerical simulations of waves are required.
Summary: This paper provides a full GPU accelerated solution of mpiPOM. We design and implement several optimizing methods:
(i) computation optimization in a single GPU
(ii) communication optimization among multiple GPUs
(iii) I/O optimization between a hybrid GPU and CPU.
Our experimental results indicate that the performance of the gpuPOM on a workstation containing 4 GPUs is comparable to a powerful cluster with 408 CPU cores and it reduces the energy consumption by 6.8 times.
Thermo-hydro-mechanical processes in fractured rock formations during glacial advance
Summary: The paper examines the coupled thermo-hydro-mechanical (THM) processes that develop in a fractured rock region within a fluid-saturated rock mass due to loads imposed by an advancing glacier. This scenario needs to be examined in order to assess the suitability of potential sites for the location of deep geologic repositories for the storage of high-level nuclear waste. The THM processes are examined using a computational multiphysics approach.