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, 0 Comments)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, 0 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, 0 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.
Simulations and parameterisation of shallow volcanic plumes of Piton de la Fournaise, La Réunion Island using Méso-NH version 4-9-3
Summary: A subgrid shallow convection scheme is adapted such that the size and intensity of the ground heat source provided by an eruption is initialised for modelling the sub-grid updraft.This parameterisation is tested on a 1D single column model with a 1 km resolution for an eruption observed at PdF in January 2010. The modelled plume agrees well with the SO2 concentrations found with LES and the adapted scheme emphasizes the sensitivity of the parameterisation to entrainment at the plume base.
libcloudph++ 0.2: single-moment bulk, double-moment bulk, and particle-based warm-rain microphysics library in C++
Summary: This paper introduces a free and open-source C++ library of algorithms for representing cloud microphysics in numerical models. In the current release, the library covers three warm-rain schemes: the single- and double-moment bulk schemes, and the particle-based scheme with Monte-Carlo coalescence. The three schemes are intended for modelling frameworks of different dimensionality and complexity ranging from parcel models to multi-dimensional cloud-resolving (e.g. large-eddy) simulations.
Albany/FELIX: a parallel, scalable and robust, finite element, first-order Stokes approximation ice sheet solver built for advanced analysis
Summary: In this manuscript, we discuss the development and validation of a new momentum balance solver for modeling the flow of glaciers and ice sheets based on the 1st order Stokes equations. We demonstrate the numerical convergence of our solver (with respect to computational mesh spacing), its flexibility (with respect to both the choice of mesh and finite element type), and its computational performance (robustness and scalability when applied to both idealized and realistic ice sheet simulations).
I. Kalashnikova, M. Perego, A. G. Salinger, R. S. Tuminaro, and S. F. Price Geosci. Model Dev. Discuss., 7, 8079-8149, 2014 AbstractDiscussion Paper (PDF, 3849 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for GMD
24 Nov 2014
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
Coupling of the VAMPER permafrost model within the earth system model iLOVECLIM (version 1.0): description and validation
A size-composition resolved aerosol model for simulating the dynamics of externally mixed particles: SCRAM (v 1.0)
Summary: This article presents a Size-Composition Resolved Aerosol Model (SCRAM) for simulating the dynamics of externally-mixed atmospheric particles. The model is first validated by comparison with a reference solution and with results of simulations using internally-mixed particles. Then, the importance of representing the mixing state when modeling atmospheric aerosol concentrations is investigated in a box model simulation using data representative of air pollution in Greater Paris.
A simulation model to assess groundwater recharge over Europe's karst regions
Summary: We present a new approach to assess groundwater recharge over Europe's karst regions.
We use cluster analysis to subdivide Europe's karst regions into four typical karst landscapes.
We apply a new large-scale simulation model for karst recharge.
We estimate its parameters by a combination of a priori information and observations of soil moisture and evapotranspiration.
We show by independent observations of recharge that present large-scale models significantly under-estimate karst recharge.
A. Hartmann, T. Gleeson, R. Rosolem, F. Pianosi, Y. Wada, and T. Wagener Geosci. Model Dev. Discuss., 7, 7887-7935, 2014 AbstractDiscussion Paper (PDF, 5589 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMD
19 Nov 2014
An observation-constrained multi-physics RCM ensemble for simulating European mega-heatwaves
Summary: Climate models are often not evaluated against observations of past climate extremes, resulting in poor performance during for instance heatwave conditions. We use a regional climate model with different atmospheric physics schemes to simulate the heatwave events of 2003 in Western Europe and 2010 in Russia. The five best performing and diverse physics scheme combinations may be used in the future to perform heatwave analysis and to investigate the impact of climate change in summer in Europe.
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, 0 Comments)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.
Tropospheric chemistry in the integrated forecasting system of ECMWF
Summary: We describe modules for atmospheric chemistry, wet and dry deposition and lightning NO production, which have been newly introduced in ECMWFs weather forecasting model. With that model we want to forecast global air pollution as part of the European Copernicus Atmosphere Monitoring Service. We show that the new model results compare as good or better with in-situ and satellite observations of ozone, CO, NO2, SO2 and formaldehyde than the previous model.
J. Flemming, V. Huijnen, J. Arteta, P. Bechtold, A. Beljaars, A.-M. Blechschmidt, B. Josse, M. Diamantakis, R. J. Engelen, A. Gaudel, A. Inness, L. Jones, E. Katragkou, V. Marecal, V.-H. Peuch, A. Richter, M. G. Schultz, O. Stein, and A. Tsikerdekis Geosci. Model Dev. Discuss., 7, 7733-7803, 2014 AbstractDiscussion Paper (PDF, 8171 KB)Supplement (95 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMDSpecial Issue
18 Nov 2014
Aerosol specification in single-column CAM5
Summary: In this study we explore the problem in running default CAM5-SCM, which initializes the aerosol to zero, and test three potential fixes in four different cloud regimes: DYCOMSRF02, MPACE-B, RICO, and ARM95. Stratiform cloud cases (DYCOMS RF02 and MPACE-B) were found to have a strong dependence on aerosol concentration, while convective cases (RICO and ARM95) were relatively insensitive to aerosol specification.
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.
Development and evaluation of the Screening Trajectory Ozone Prediction System (STOPS, version 1.0)
Summary: This paper presents development and evaluation a hybrid Lagrangian-Eulerian modeling tool. In this tool, a small sub-domain follows a trajectory defined by the mean mixed-layer wind. The advantage of this tool compared to other Lagrangian models is its capability of utilizing realistic boundary conditions that change with space and time as well as a detailed treatment of chemical reactions.
Reduction of predictive uncertainty in estimating irrigation water requirement through multi-model ensembles and ensemble averaging
Summary: Irrigation agriculture is required to sustain yields that allow feeding the world population. A robust assessment of irrigation requirement (IRR) relies on a sound quantification of evapotranspiration (ET). We prepared a multi-model ensemble considering several ET methods and investigate uncertainties in simulating IRR. More generally, we provide an example of the value of investigating the uncertainty in models that may be used to inform policy-making and to elaborate best management practices.
S. Multsch, J.-F. Exbrayat, M. Kirby, N. R. Viney, H.-G. Frede, and L. Breuer Geosci. Model Dev. Discuss., 7, 7525-7558, 2014 AbstractDiscussion Paper (PDF, 1366 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for GMD
10 Nov 2014
Development of a grid-independent GEOS-chem chemical transport model as an atmospheric chemistry module for Earth System Models
Summary: This paper presents results from the modularization of the GEOS-Chem Chemical Transport Model, and its coupling as the chemical operator within the NASA-GMAO GEOS-5 Earth System Model (ESM). The key findings are that chemistry within the modular GEOS-Chem system shows consistent, high strong-scaling properties across the range of distributed processors, transport is the limiting component prohibiting efficient scalability, and GEOS-Chem is able to generate suitable chemical results in an ESM.
M. S. Long, R. Yantosca, J. E. Nielsen, C. A. Keller, A. da Silva, M. P. Sulprizio, S. Pawson, and D. J. Jacob Geosci. Model Dev. Discuss., 7, 7505-7524, 2014 AbstractDiscussion Paper (PDF, 2955 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for GMD
10 Nov 2014
Carbon isotopes in the ocean model of the Community Earth System Model (CESM1)
Summary: Carbon isotopes have been added to the ocean model of the Community Earth System Model version 1 (CESM1). This paper describes the details of how the abiotic 14C tracer and the biotic 13C and 14C tracers were added to the existing ocean model of the CESM. In addition, it shows first results of the new model features compared to observational data for the 1990s.
A. Jahn, K. Lindsay, X. Giraud, N. Gruber, B. L. Otto-Bliesner, Z. Liu, and E. C. Brady Geosci. Model Dev. Discuss., 7, 7461-7503, 2014 AbstractDiscussion Paper (PDF, 4005 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMD
06 Nov 2014
An approach to enhance pnetCDF performance in environmental modeling applications
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.
EDDA: integrated simulation of debris flow erosion, deposition and property changes
Summary: A new numerical model, EDDA, is developed for simulating debris-flow erosion, deposition, and associated changes in debris mass, properties and topography. A variable time step algorithm is adopted to assure both numerical accuracy and computational efficiency. The performance of the model has been verified through four numerical tests and a large-scale case study. EDDA can be a powerful tool for debris-flow risk assessment in a large area and real-time landslide warning.
An integrated user-friendly ArcMAP tool for bivariate statistical modeling in geoscience applications
Summary: The main contributions of this manuscript are:
• A novel an easy to use ArcMap tool is proposed for bivariate statistical analysis model implementation.
• The developed tool facilitated and speed up the BSA modeling process of frequency ratio, weights-of-evidence, and evidential belief function.
• This tool classifies the variables based on the acquired weights automatically.
• All three methods were tested on a study area and landslide susceptibility maps were produced.
Technical challenges and solutions in representing lakes when using WRF in downscaling applications
M. S. Mallard, C. G. Nolte, T. L. Spero, O. R. Bullock, K. Alapaty, J. A. Herwehe, J. Gula, and J. H. Bowden Geosci. Model Dev. Discuss., 7, 7121-7150, 2014 AbstractDiscussion Paper (PDF, 639 KB)Interactive Discussion (Open, 3 Comments)Manuscript under review for GMD
27 Oct 2014
A simple object-oriented and open source model for scientific and policy analyses of the global carbon cycle – Hector v0.1
Summary: Simple climate models play an integral role in policy and scientific communities. Hector v0.1 is an open source, object-oriented, simple global climate carbon-cycle model. It runs essentially instantaneously while still representing the most critical earth system processes. Hector reproduces the global historical trends of atmospheric [CO2] and surface temperatures and simulates all four Representative Concentration Pathways.
C. A. Hartin, P. Patel, A. Schwarber, R. P. Link, and B. P. Bond-Lamberty Geosci. Model Dev. Discuss., 7, 7075-7119, 2014 AbstractDiscussion Paper (PDF, 2188 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMD
24 Oct 2014
Global sensitivity analysis, probabilistic calibration, and predictive assessment for the Data Assimilation Linked Ecosystem Carbon model
Summary: In this paper we propose a probabilistic framework for an uncertainty quantification study of a Carbon cycle model. We study model parameters via Global Sensitivity Analysis and employ a Bayesian approach to
calibrate these parameters using net ecosystem exchange observations at the Harvard Forest site. Overall, this study leads to a 40% improvement in the predictive skill of the Carbon cycle model and highlights the importance of considering parameter correlations as informed by the data.
C. Safta, D. Ricciuto, K. Sargsyan, B. Debusschere, H. N. Najm, M. Williams, and P. Thornton Geosci. Model Dev. Discuss., 7, 6893-6948, 2014 AbstractDiscussion Paper (PDF, 2971 KB)Interactive Discussion (Open, 1 Comment)Manuscript under review for GMD
15 Oct 2014
A test of an optimal stomatal conductance scheme within the CABLE Land Surface Model
Summary: Stomatal conductance (gs) affects the fluxes of carbon, energy and water between the vegetated land surface and the atmosphere. We test an implementation of an optimal stomatal conductance model within the CABLE land surface model (LSM). The new implementation resulted in a large reduction in the annual fluxes of transpiration across evergreen needleleaf, tundra and C4 grass regions. Optimisation theory can yield a simple and tractable approach to predicting gs in LSMs.
M. G. De Kauwe, J. Kala, Y.-S. Lin, A. J. Pitman, B. E. Medlyn, R. A. Duursma, G. Abramowitz, Y.-P. Wang, and D. G. Miralles Geosci. Model Dev. Discuss., 7, 6845-6891, 2014 AbstractDiscussion Paper (PDF, 5076 KB)Interactive Discussion (Open, 2 Comments)Manuscript under review for GMD
NEMOTAM: tangent and adjoint models for the ocean modelling platform NEMO
Summary: This paper presents tha tangent and adjoint models for the NEMO ocean modelling framework. They are useful tools for sensitivity and stability analysis. The implementation choices and the validation of the code is presented as well as a selection of applications.