ALBERT

Description: MicroHH 1.0: a computational fluid dynamics code for direct numerical simulation and large-eddy simulation of atmospheric boundary layer flows Chiel C. van Heerwaarden, Bart J. H. van Stratum, Thijs Heus, Jeremy A. Gibbs, Evgeni Fedorovich, and Juan-Pedro Mellado Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-41,2017 Manuscript under review for GMD (discussion: open, 0 comments) MicroHH ( ww.microhh.org ) is a new and open source computational fluid dynamics code for the simulation of turbulent flows in the atmosphere. It is made the simulate atmospheric flows up to the finest detail levels at very high resolution. It has been designed from scratch in order to use a modern design that allows the code to run on more than 10.000 cores, as well as on a Graphical Processing Unit.

Description: Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emission Data System (CEDS) Rachel M. Hoesly, Steven J. Smith, Leyang Feng, Zbigniew Klimont, Greet Janssens-Maenhout, Tyler Pitkanen, Jonathan J. Seibert, Linh Vu, Robert J. Andres, Ryan M. Bolt, Tami C. Bond, Laura Dawidowski, Nazar Kholod, Jun-ichi Kurokawa, Meng Li, Liang Liu, Zifeng Lu, Maria Cecilia P. Moura, Patrick R. O'Rourke, and Qiang Zhang Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-43,2017 Manuscript under review for GMD (discussion: open, 0 comments) Historical emission trends are key inputs to earth systems and atmospheric chemistry models. We present a new data set of historical (1750–2014) anthropogenic gases (CO, CH 4 , NH 3 , NO X , SO 2 , NMVOC, BC, OC, and CO 2 ) developed with the Community Emissions Database System (CEDS). This improves on existing inventories as it uses consistent methods and data across emissions species, has annual resolution for a longer and more recent time series, and is designed to be transparent and reproducible.

Description: Evaluating the effect of alternative carbon allocation schemes in a land surface model (CLM4.5) on carbon fluxes, pools and turnover in temperate forests Francesc Montané, Andrew M. Fox, Avelino F. Arellano, Natasha MacBean, M. Ross Alexander, Alex Dye, Daniel A. Bishop, Valerie Trouet, Flurin Babst, Amy E. Hessl, Neil Pederson, Peter D. Blanken, Gil Bohrer, Christopher M. Gough, Marcy E. Litvak, Kimberly A. Novick, Richard P. Phillips, Jeffrey D. Wood, and David J. P. Moore Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-74,2017 Manuscript under review for GMD (discussion: open, 0 comments) How carbon is allocated to different plant tissues (leaves, stem, and roots) determines carbon residence time and thus remains a central challenge for understanding the global carbon cycle. In this paper, we used a state-of-the-art land surface model (CLM4.5) with its standard carbon allocation scheme, and we implemented alternative carbon allocation schemes based on published papers. One of the alternative allocation schemes improved aboveground biomass estimates in most of our sites.

Description: The Fire Modeling Intercomparison Project (FireMIP), phase 1: experimental and analytical protocols with detailed model descriptions Sam S. Rabin, Joe R. Melton, Gitta Lasslop, Dominique Bachelet, Matthew Forrest, Stijn Hantson, Jed O. Kaplan, Fang Li, Stéphane Mangeon, Daniel S. Ward, Chao Yue, Vivek K. Arora, Thomas Hickler, Silvia Kloster, Wolfgang Knorr, Lars Nieradzik, Allan Spessa, Gerd A. Folberth, Tim Sheehan, Apostolos Voulgarakis, Douglas I. Kelley, I. Colin Prentice, Stephen Sitch, Sandy Harrison, and Almut Arneth Geosci. Model Dev., 10, 1175-1197, doi:10.5194/gmd-10-1175-2017, 2017 Global vegetation models are important tools for understanding how the Earth system will change in the future, and fire is a critical process to include. A number of different methods have been developed to represent vegetation burning. This paper describes the protocol for the first systematic comparison of global fire models, which will allow the community to explore various drivers and evaluate what mechanisms are important for improving performance. It also includes equations for all models.

Description: A Bayesian posterior predictive framework for weighting ensemble regional climate models Yanan Fan, Roman Olson, and Jason P. Evans Geosci. Model Dev., 10, 2321-2332, https://doi.org/10.5194/gmd-10-2321-2017, 2017 We develop a novel and principled Bayesian statistical approach to computing model weights in climate change projection ensembles of regional climate models. The approach accounts for uncertainty in model bias, trend and internal variability. The weights are easily interpretable and the ensemble weighted models are shown to provide the correct coverage and improve upon existing methods in terms of providing narrower confidence intervals for climate change projections.

Description: Sea-ice evaluation of NEMO-Nordic 1.0: a NEMO–LIM3.6 based ocean–sea ice model setup for the North Sea and Baltic Sea Per Pemberton, Ulrike Löptien, Robinson Hordoir, Anders Höglund, Semjon Schimanke, Lars Axell, and Jari Haapala Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-10,2017 Manuscript under review for GMD (discussion: open, 0 comments) The Baltic Sea is seasonally ice covered with intense wintertime ship traffic and a sensitive ecosystem. Understanding the sea-ice pack is important for climate effect studies and forecasting. Our work introduces a new model setup for the North Sea/Baltic Sea and a new method to handle ice in the coastal zone, an important feature in the Baltic Sea. We evaluate different sea ice parameters and overall finds that the model agrees well with the observation and is well suited for further studies.

Description: Implementation of methane cycling for deep time, global warming simulations with the DCESS Earth System Model (Version 1.2) Gary Shaffer, Esteban Fernández Villanueva, Roberto Rondanelli, Jens Olaf Pepke Pedersen, Steffen Malskær Olsen, and Matthew Huber Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-23,2017 Manuscript under review for GMD (discussion: open, 0 comments) We include methane cycling in the simplified but well-tested Danish Center for Earth System Science model. We now can deal with very large methane inputs to the Earth System that can lead to much methane in the atmosphere, extreme warming and ocean dead zones. We now can study ancient global warming events, probably forced by methane inputs. Some such events were accompanied by mass extinctions. We wish to understand such events, both for learning about the past and for looking into the future.

Description: Exploring new topography-based subgrid spatial structures for improving land surface modeling Teklu K. Tesfa and Lai-Yung Ruby Leung Geosci. Model Dev., 10, 873-888, doi:10.5194/gmd-10-873-2017, 2017 Motivated by the significant topographic influence on land surface processes, this study explored two methods to discretize watersheds into two types of subgrid structures to capture spatial heterogeneity for land surface models. Adopting geomorphologic concepts in watershed discretization yields improved capability in capturing subgrid topographic heterogeneity, which also allowed climatic and land cover variability to be better represented with a nominal increase in computational requirements.

Description: Efficiently modelling urban heat storage: an interface conduction scheme in an urban land surface model (aTEB v2.0) Mathew J. Lipson, Melissa A. Hart, and Marcus Thatcher Geosci. Model Dev., 10, 991-1007, doi:10.5194/gmd-10-991-2017, 2017 City-scale models describing the surface energy balance have difficulties representing heat storage in urban materials. This paper proposes an alternative method to discretise heat conduction through urban materials. We compare the new method with an approach commonly used in urban models and find the new method better matches exact solutions to heat transfer for a wide variety of urban material compositions. We also find the new method improves the bulk energy flux response of an urban model.

Description: Influence of bulk microphysics schemes upon Weather Research and Forecasting (WRF) version 3.6.1 nor'easter simulations Stephen D. Nicholls, Steven G. Decker, Wei-Kuo Tao, Stephen E. Lang, Jainn J. Shi, and Karen I. Mohr Geosci. Model Dev., 10, 1033-1049, doi:10.5194/gmd-10-1033-2017, 2017 This study evaluated the impact of five hydrometeor species physics schemes during seven intense winter storm events in the northeastern United States. Model simulations were evaluated against gridded analysis data, precipitation, and weather radar derived products. Results show minor differences in simulated precipitation and large-scale regional patterns, yet simulated weather radar fields were more accurate in physics schemes with less ice pellet content above the melting layer.

Description: Explicit and parametrised representation of under ice shelf seas in a z * coordinate ocean model Pierre Mathiot, Adrian Jenkins, Christopher Harris, and Gurvan Madec Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-37,2017 Manuscript under review for GMD (discussion: open, 0 comments) Ice shelf/ocean interactions are a major source of fresh water on the Antarctic continental shelf and have a strong impact on ocean properties, ocean circulation and sea ice. However, climate models based on the ocean/sea ice model NEMO currently do not include these interactions in any detail. The capability of explicitly simulating the circulation beneath ice shelves is introduced in the non-linear free surface model NEMO. Its implementation into the NEMO framework and its assessment in an idealised and realistic circum-Antarctic configuration is described in this study. Compared with the current prescription of ice shelf melting (i.e. at the surface) inclusion of open sub-ice-shelf leads to a decrease sea ice thickness along the coast, a weakening of the ocean stratification on the shelf, a decrease in salinity of HSSW on the Ross and Weddell Sea shelves and an increase in the strength of the gyres that circulate within the over-deepened basins on the West Antarctic continental shelf. Mimicking the under ice shelf seas overturning circulation by introducing the meltwater over the depth range of the ice shelf base, rather than at the surface is also tested. It yields similar improvements in the simulated ocean properties and circulation over the Antarctic continental shelf than the explicit ice shelf cavity representation. With the ice shelf cavities opened, the widely-used “3 equations” ice shelf melting formulation enables an interactive computation of melting that has been assessed. Comparison with observational estimates of ice shelf melting indicates realistic results for most ice shelves. However, melting rates for Amery, Getz and George VI ice shelves are considerably overestimated.

Description: Online dynamical downscaling of temperature and precipitation within the iLOVECLIM model (version 1.1) Aurélien Quiquet, Didier M. Roche, Christophe Dumas, and Didier Paillard Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-116,2017 Manuscript under review for GMD (discussion: open, 0 comments) Earth system models of intermediate complexity have generally a simplified model physics and a coarse model resolution. In this work we present the inclusion of an online dynamical downscaling of temperature and precipitation in such a model. This downscaling explicitly takes into account sub-grid topography. With this new model functionality we are able to simulate temperature and precipitation on a 40 km grid for the whole Northern Hemisphere from the native model resolution.

Description: Evaluation of five dry particle deposition parameterizations for incorporation into atmospheric transport models Tanvir R. Khan and Judith A. Perlinger Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-93,2017 Manuscript under review for GMD (discussion: open, 0 comments) Despite considerable effort to develop mechanistic dry particle deposition parameterizations for atmospheric transport models, current knowledge has been inadequate to propose quantitative measures of the relative performance of available parameterizations. In this study, we evaluated the performance of five dry particle deposition parameterizations developed by Zhang et al. (2001) ( Z01 ), Petroff and Zhang (2010) ( PZ10 ), Kouznetsov and Sofiev (2012) ( KS12 ), Zhang and He (2014) ( ZH14 ), and Zhang and Sao (2014) ( ZS14 ), respectively. The evaluation was performed in three dimensions: model ability to reproduce observed deposition velocities, V d (accuracy), the influence of imprecision in input parameter values on the modeled V d (uncertainty), and identification of the most influential parameter(s) (sensitivity). The accuracy of the modeled V d was evaluated using observations obtained from five land use categories (LUCs): grass, coniferous and deciduous forests, natural water, and ice/snow. To ascertain the uncertainty in modeled V d , and quantify the influence of imprecision in key model input parameters, a Monte Carlo uncertainty analysis was performed. The Sobol' sensitivity analysis was conducted with the objective to determine the parameter ranking, from the most to the least influential. Comparing the normalized mean bias factors (indicator of accuracy), we find that the ZH14 parameterization is the most accurate for all LUCs except for coniferous forest, for which it is second most accurate (B NMBF  = −2.31). From Monte Carlo simulations, the estimated mean normalized uncertainties in the modeled Vd obtained for seven particle sizes (ranging from 0.005 to 2.5 μm) for the five LUCs are 17 %, 12 %, 13 %, 16 %, and 27 % for the Z01 , PZ10 , KS12 , ZH14 , and ZS14 parameterizations, respectively. From the Sobol' sensitivity results, we suggest that the parameter rankings vary by particle size and LUC for a given parameterization. Overall, for d p  = 0.001 to 1.0 μm, friction velocity was one of the three most influential parameters in all parameterizations. For giant particles ( d p  = 10 μm), relative humidity was the most influential parameter. Because it is the least complex of the five parameterizations, and it has the greatest accuracy and least uncertainty, we propose that the ZH14 parameterization is currently superior for incorporation into atmospheric transport models.

Description: The UKC2 regional coupled environmental prediction system Huw W. Lewis, Juan Manuel Castillo Sanchez, Jennifer Graham, Andrew Saulter, Jorge Bornemann, Alex Arnold, Joachim Fallmann, Chris Harris, David Pearson, Steven Ramsdale, Alberto Martínez de la Torre, Lucy Bricheno, Eleanor Blyth, Vicky Bell, Helen Davies, Toby R. Marthews, Clare O'Neill, Heather Rumbold, Enda O'Dea, Ashley Brereton, Karen Guihou, Adrian Hines, Momme Butenschon, Simon J. Dadson, Tamzin Palmer, Jason Holt, Nick Reynard, Martin Best, John Edwards, and John Siddorn Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-110,2017 Manuscript under review for GMD (discussion: open, 0 comments) In the real world the atmosphere, oceans and land surface are closely interconnected, and yet prediction systems tend to treat them in isolation. Those feedbacks are often illustrated in natural hazards, such as when strong winds lead to large waves and coastal damage, or when prolonged rainfall leads to saturated ground and high flowing rivers. For the first time, we have attempted to represent some of the feedbacks between sky, sea and land within a high resolution forecast system for the UK.

Description: A multi-species data assimilation system to retrieve information on land-atmosphere exchange processes Ivar R. van der Velde, John B. Miller, Michiel K. van der Molen, Pieter P. Tans, Bruce H. Vaughn, James W.C. White, Kevin Schaefer, and Wouter Peters Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-84,2017 Manuscript under review for GMD (discussion: open, 0 comments) We explored an inverse modeling technique to interpret global atmospheric measurements of CO 2 and the ratio of its stable carbon isotopes (δ 13 C). We detected the possible underestimation of drought stress in biosphere models after applying combined atmospheric CO 2 and δ 13 C constraints. This study highlights the importance to improve the representation of the biosphere in carbon-climate models, especially in a world where droughts become more extreme and more frequent.

Description: Correct boundary conditions for DNS models of nonlinear acoustic-gravity waves forced by atmospheric pressure variations Yuliya Kurdyaeva, Sergey Kshevetskii, Nikolay Gavrilov, and Sergey Kulichkov Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-76,2017 Manuscript under review for GMD (discussion: open, 0 comments) Various meteorological phenomena generate acoustic-gravity waves in the atmosphere and cause wave variations of atmospheric pressure. There are networks of microbarographs, which record pressure variations on the Earth's surface. The hydrodynamic problem of propagation of waves in the atmosphere from pressure variations on the Earth's surface is formulated. The problem wellposedness is proved. A supercomputer program for simulation of waves from pressure variations is developed and applied.

Description: Soil Methanotrophy Model (MeMo v1.0): a process-based model to quantify global uptake of atmospheric methane by soil Fabiola Murguia-Flores, Sandra Arndt, Anita L. Ganesan, Guillermo N. Murray-Tortarolo, and Edward R. C. Hornibrook Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-124,2017 Manuscript under review for GMD (discussion: open, 0 comments) Soil bacteria known as methanotrophs are the only biological sink for atmospheric methane (CH 4 ). Their activity depends on climatic and edaphic conditions, thus varies spatially and temporarily. Based on this, we developed a model (MeMo v1.0) to assess the global CH 4 consumption by soils.The global CH 4 uptake was 34.3 Tg CH 4  yr −1 for the period 1990–2009, with an increasing trend of 0.1 Tg CH 4  yr −2 . The regional analysis proved that warm and semiarid regions represent the most efficient CH 4 sink.

Description: High Performance Software Framework for the Calculation of Satellite-to-Satellite Data Matchups (MMS version 1.2) Thomas Block, Sabine Embacher, Christopher J. Merchant, and Craig Donlon Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-54,2017 Manuscript under review for GMD (discussion: open, 0 comments) For calibration and validation purposes it is nesessary to detect simultaneous data acquisitions from different space borne platforms. We present an algorithm and a software system which implements a general approach to resolve this problem. The Multisensor Matchup System (MMS) can detect simultaneous acquisitions in a large dataset (〉 100 TB) and extract data for matching locations for further analysis. The MMS implements a flexible software infrastructure and allows for high parallelisation.

Description: Carbon–nitrogen interactions in idealized simulations with JSBACH (version 3.10) Daniel S. Goll, Alexander J. Winkler, Thomas Raddatz, Ning Dong, Ian Colin Prentice, Philippe Ciais, and Victor Brovkin Geosci. Model Dev., 10, 2009-2030, https://doi.org/10.5194/gmd-10-2009-2017, 2017 The response of soil organic carbon decomposition to warming and the interactions between nitrogen and carbon cycling affect the feedbacks between the land carbon cycle and the climate. In the model JSBACH carbon–nitrogen interactions have only a small effect on the feedbacks, whereas modifications of soil organic carbon decomposition have a large effect. The carbon cycle in the improved model is more resilient to climatic changes than in previous version of the model.

Description: A non-linear Granger-causality framework to investigate climate–vegetation dynamics Christina Papagiannopoulou, Diego G. Miralles, Stijn Decubber, Matthias Demuzere, Niko E. C. Verhoest, Wouter A. Dorigo, and Willem Waegeman Geosci. Model Dev., 10, 1945-1960, https://doi.org/10.5194/gmd-10-1945-2017, 2017 Global satellite observations provide a means to unravel the influence of climate on vegetation. Common statistical methods used to study the relationships between climate and vegetation are often too simplistic to capture the complexity of these relationships. Here, we present a novel causality framework that includes data fusion from various databases, time series decomposition, and machine learning techniques. Results highlight the highly non-linear nature of climate–vegetation interactions.

Description: Variational assimilation of IASI SO 2 plume height and total column retrievals in the 2010 eruption of Eyjafjallajökull using the SILAM v5.3 chemistry transport model Julius Vira, Elisa Carboni, Roy G. Grainger, and Mikhail Sofiev Geosci. Model Dev., 10, 1985-2008, https://doi.org/10.5194/gmd-10-1985-2017, 2017 The vertical and temporal distributions of sulfur dioxide emissions during the 2010 eruption of Eyjafjallajökull were reconstructed by combining data from the IASI satellite instrument with a dispersion model. Unlike in previous studies, both column density (the total amount above a given point) and the plume height were derived from the satellite data. This resulted in more accurate simulated vertical distributions for the times when the emission was not constrained by the column densities.

Description: GLEAM v3: satellite-based land evaporation and root-zone soil moisture Brecht Martens, Diego G. Miralles, Hans Lievens, Robin van der Schalie, Richard A. M. de Jeu, Diego Fernández-Prieto, Hylke E. Beck, Wouter A. Dorigo, and Niko E. C. Verhoest Geosci. Model Dev., 10, 1903-1925, https://doi.org/10.5194/gmd-10-1903-2017, 2017 Terrestrial evaporation is a key component of the hydrological cycle and reliable data sets of this variable are of major importance. The Global Land Evaporation Amsterdam Model (GLEAM, www.GLEAM.eu ) is a set of algorithms which estimates evaporation based on satellite observations. The third version of GLEAM, presented in this study, includes an improved parameterization of different model components. As a result, the accuracy of the GLEAM data sets has been improved upon previous versions.

Description: Evaluation of high-resolution GRAMM/GRAL NO x simulations over the city of Zurich, Switzerland Antoine Berchet, Katrin Zink, Dietmar Oettl, Jürg Brunner, Lukas Emmenegger, and Dominik Brunner Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-102,2017 Manuscript under review for GMD (discussion: open, 0 comments) Hourly NO x concentrations were simulated for the city of Zurich, Switzerland, at 10 m resolution for the years 2013–2014. The simulations were generated with the nested mesoscale meteorology and microscale dispersion model system GRAMM/GRAL (versions v15.12/v14.8) by applying a catalogue-based approach. This approach was specifically designed to enable long-term city-wide building-resolving simulations with affordable computation costs. It relies on a discrete set of possible weather situations and corresponding steady-state flow and dispersion patterns that are pre-computed and then matched hourly with actual meteorological observations. The modelling system was comprehensively evaluated using eight sites continuously monitoring NO x concentrations and 65 passive samplers measuring NO 2 concentrations on a 2-weekly basis all over the city. The system was demonstrated to fulfil the European Commission standards for air pollution modelling at nearly all sites. The average spatial distribution was very well represented, despite a general tendency to overestimating the observed concentrations, possibly due to a crude representation of traffic-induced turbulence. The temporal variability of concentrations explained by varying emissions and weather situations was accurately reproduced on different time scales. The seasonal cycle of concentrations, mostly driven by stronger vertical dispersion in summer than in winter, was very well captured in the two year simulation period. Short-term events, such as episodes of particularly high and low concentrations, were detected in most cases by the system, although some unrealistic pollution peaks were occasionally generated, pointing at some limitations of the steady-state approximation. The different patterns of the diurnal cycle of concentrations observed in the city were generally well captured as well. The evaluation confirmed the adequacy of the catalogue-based approach in the context of city scale air pollution modelling. The ability to reproduce not only the spatial gradients but also the hourly temporal variability over multiple years makes the model system particularly suitable for investigating individualized air pollution exposure in the city.

Description: Exploring precipitation pattern scaling methodologies and robustness among CMIP5 models Ben Kravitz, Cary Lynch, Corinne Hartin, and Ben Bond-Lamberty Geosci. Model Dev., 10, 1889-1902, https://doi.org/10.5194/gmd-10-1889-2017, 2017 Pattern scaling is a way of approximating regional changes without needing to run a full, complex global climate model. We compare two methods of pattern scaling for precipitation and evaluate which methods is better in particular circumstances. We also decompose precipitation into a CO 2 portion and a non-CO 2 portion. The methodologies discussed in this paper can help provide precipitation fields for other models for a wide variety of scenarios of future climate change.

Description: Studying the Impact of Radioactive Charging on the Microphysical Evolution and Transport of Radioactive Aerosols with the TOMAS-RC v1 framework Petros Vasilakos, Yong-Ηa Kim, Jeffrey R. Pierce, Sotira Yiacoumi, Costas Tsouris, and Athanasios Nenes Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-96,2017 Manuscript under review for GMD (discussion: open, 2 comments) Radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. We extend a well-established model that simulates the evolution of atmospheric particulate matter to account for radioactive charging effects in an accurate and computationally efficient way. It is shown that radioactivity can strongly impact the deposition patterns of aerosol.

Description: The operational eEMEP model version 10.4 for volcanic SO 2 and ash forecasting Birthe M. Steensen, Michael Schulz, Peter Wind, Álvaro M. Valdebenito, and Hilde Fagerli Geosci. Model Dev., 10, 1927-1943, https://doi.org/10.5194/gmd-10-1927-2017, 2017 The operational emergency version of the EMEP MSC-W model for dispersion calculations of volcanic SO 2 and ash is described. Additions and changes to the standard EMEP MSC-W are presented. Grid resolution dependencies for meteorological data and numerical diffusion are studied by investigating model results driven by ensemble meteorological data for volcanic SO 2 emissions. The vertical ash layer sensitivity on gravitational settling is evaluated by comparing model results to lidar observations.

Description: Evaluation of the wind farm parameterization in the Weather Research and Forecasting model (version 3.8.1) with meteorological and turbine power data Joseph C. Y. Lee and Julie K. Lundquist Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-128,2017 Manuscript under review for GMD (discussion: open, 2 comments) We evaluate the the wind farm parameterization (WFP) in the Weather Research and Forecasting (WRF) model, a powerful tool to simulate wind farms and their meteorological impacts numerically. In our case study, the WFP-simulations with fine vertical grid resolution are skillful in matching the winds and the power production to the observations. Moreover, the WFP tends to underestimate power in windy conditions. We also illustrate the modeled wind speed is the critical factor influencing the WFP.

Description: A prognostic pollen emissions model for climate models (PECM1.0) Matthew C. Wozniak and Allison Steiner Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-105,2017 Manuscript under review for GMD (discussion: open, 0 comments) A new parameterization, Pollen Emissions for Climate Models (PECM), has been developed for use in climate models. New developments include 1) a new climate-sensitive, observation-based phenological model, 2) inclusion of the 13 highest-pollinating taxa in the United States, and 3) an option to compute pollen emissions by plant functional type (PFT). It can be used to address topics like impacts of climate change (e.g. on allergen exposure, on plant ecology) or pollen as an atmospheric aerosol.

Description: Evaluation of Integrated Assessment Model hindcast experiments: A case study of the GCAM 3.0 land use module Abigail C. Snyder, Robert P. Link, and Katherine V. Calvin Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-97,2017 Manuscript under review for GMD (discussion: open, 0 comments) Experiments conducting a model forecast for a period in which observational data is available are rarely undertaken in the Integrated Assessment Model (IAM) community. When undertaken, results are often evaluated using global aggregates that mask deficiencies. Comparing land allocation simulations in GCAM with FAO observational data from 1990–2010, we find quantitative evidence that global aggregates alone are not sufficient for evaluating IAMs with global supply constraints similar to GCAM.

Description: CITRATE 1.0: Phytoplankton continuous trait-distribution model with one-dimensional physical transport applied to the Northwest Pacific Bingzhang Chen and S. Lan Smith Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-104,2017 Manuscript under review for GMD (discussion: open, 0 comments) Marine phytoplankton accounts for half of global primary production. Phytoplankton size is an important trait affecting its fitness and ecosystem functioning. We have developed a plankton model with continuous size distribution for phytoplankton and applied it in the North Pacific. This model is able to capture the general patterns of phytoplankton size distribution in the real ocean and can be used for understanding the mechanisms controlling phytoplankton size structure and diversity.

Description: SedFoam-2.0: a 3D two-phase flow numerical model for sediment transport Julien Chauchat, Zhen Cheng, Tim Nagel, Cyrille Bonamy, and Tian-Jian Hsu Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-101,2017 Manuscript under review for GMD (discussion: open, 0 comments) This manuscript presents the development and validation of a community two-phase flow Eulerian-Eulerian model based on openFoam for sediment transport applications. The mathematical and numerical models are described in details. Two simple validation test cases, sedimentation and a pressure driven sediment transport in the laminar flow regime, are presented. Finally, the model is applied to two reallistic sediment transport configurations, intense bed-load transport and scour at an apron.

Description: Biogeochemical protocols and diagnostics for the CMIP6 Ocean Model Intercomparison Project (OMIP) James C. Orr, Raymond G. Najjar, Olivier Aumont, Laurent Bopp, John L. Bullister, Gokhan Danabasoglu, Scott C. Doney, John P. Dunne, Jean-Claude Dutay, Heather Graven, Stephen M. Griffies, Jasmin G. John, Fortunat Joos, Ingeborg Levin, Keith Lindsay, Richard J. Matear, Galen A. McKinley, Anne Mouchet, Andreas Oschlies, Anastasia Romanou, Reiner Schlitzer, Alessandro Tagliabue, Toste Tanhua, and Andrew Yool Geosci. Model Dev., 10, 2169-2199, https://doi.org/10.5194/gmd-10-2169-2017, 2017 The Ocean Model Intercomparison Project (OMIP) is a model comparison effort under Phase 6 of the Coupled Model Intercomparison Project (CMIP6). Its physical component is described elsewhere in this special issue. Here we describe its ocean biogeochemical component (OMIP-BGC), detailing simulation protocols and analysis diagnostics. Simulations focus on ocean carbon, other biogeochemical tracers, air-sea exchange of CO2 and related gases, and chemical tracers used to evaluate modeled circulation.

Description: Historical greenhouse gas concentrations for climate modelling (CMIP6) Malte Meinshausen, Elisabeth Vogel, Alexander Nauels, Katja Lorbacher, Nicolai Meinshausen, David M. Etheridge, Paul J. Fraser, Stephen A. Montzka, Peter J. Rayner, Cathy M. Trudinger, Paul B. Krummel, Urs Beyerle, Josep G. Canadell, John S. Daniel, Ian G. Enting, Rachel M. Law, Chris R. Lunder, Simon O'Doherty, Ron G. Prinn, Stefan Reimann, Mauro Rubino, Guus J. M. Velders, Martin K. Vollmer, Ray H. J. Wang, and Ray Weiss Geosci. Model Dev., 10, 2057-2116, https://doi.org/10.5194/gmd-10-2057-2017, 2017 Climate change is primarily driven by human-induced increases of greenhouse gas (GHG) concentrations. Based on ongoing community efforts (e.g. AGAGE and NOAA networks, ice cores), this study presents historical concentrations of CO 2 , CH 4 , N 2 O and 40 other GHGs from year 0 to year 2014. The data is recommended as input for climate models for pre-industrial, historical runs under CMIP6. Global means, but also latitudinal by monthly surface concentration fields are provided.

Description: Continuous high-resolution midlatitude-belt simulations for July–August 2013 with WRF Thomas Schwitalla, Hans-Stefan Bauer, Volker Wulfmeyer, and Kirsten Warrach-Sagi Geosci. Model Dev., 10, 2031-2055, https://doi.org/10.5194/gmd-10-2031-2017, 2017 Due to computational constraints, extended-range forecasts on the convection-permitting (CP) scale are often performed using a limited-area model. To overcome disturbances by lateral boundary conditions, a CP latitude belt simulation in the Northern Hemisphere was performed for July and August 2013. This approach allows for the study of resolution and parameterization impacts. The results demonstrate an improved representation of the general circulation and precipitation patterns.

Description: Sequential assimilation of satellite-derived vegetation and soil moisture products using SURFEX_v8.0: LDAS-Monde assessment over the Euro-Mediterranean area Clément Albergel, Simon Munier, Delphine Jennifer Leroux, Hélène Dewaele, David Fairbairn, Alina Lavinia Barbu, Emiliano Gelati, Wouter Dorigo, Stéphanie Faroux, Catherine Meurey, Patrick Le Moigne, Bertrand Decharme, Jean-Francois Mahfouf, and Jean-Christophe Calvet Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-121,2017 Manuscript under review for GMD (discussion: open, 0 comments) LDAS-Monde, A global Land Data Assimilation system, is tested over Europe and the Mediterranean basin to increase monitoring accuracy for land surface variables. It is able to ingest information from satellite-derived Surface Soil Moisture (SSM) and Leaf Area Index (LAI) observations to constrain the ISBA land surface model coupled with the CTRIP continental hydrological system. Assimilation of SSM and LAI leads to a better representation of evapotranspiration and gross primary production.

Description: Vorticity-divergence semi-Lagrangian global atmospheric model SL-AV20: dynamical core Mikhail Tolstykh, Vladimir Shashkin, Rostislav Fadeev, and Gordey Goyman Geosci. Model Dev., 10, 1961-1983, https://doi.org/10.5194/gmd-10-1961-2017, 2017 We present the hydrostatic dynamical core of the SL-AV20 global atmosphere model used for operational numerical weather prediction in Russia. The article describes model design, particularly vorticity-divergence formulation combined with the use of an unstaggerred grid. The model has an option to use a reduced latitude-longitude grid. The results for standard tests agree well with reference solutions.

Description: A global wetland methane emissions and uncertainty dataset for atmospheric chemical transport models (WetCHARTs version 1.0) A. Anthony Bloom, Kevin W. Bowman, Meemong Lee, Alexander J. Turner, Ronny Schroeder, John R. Worden, Richard Weidner, Kyle C. McDonald, and Daniel J. Jacob Geosci. Model Dev., 10, 2141-2156, https://doi.org/10.5194/gmd-10-2141-2017, 2017 Wetland emissions are a principal source of uncertainty in the global atmospheric methane budget due to poor knowledge of wetland processes. We construct a wetland methane emission and uncertainty dataset for use in global atmospheric methane models. Our wetland model ensemble is based on static wetland maps, satellite-derived inundation and carbon cycle models. The ensemble performs favourably against regional flux estimates and atmospheric methane measurements relative to previous studies.

Description: JIGSAW-GEO (1.0): locally orthogonal staggered unstructured grid generation for general circulation modelling on the sphere Darren Engwirda Geosci. Model Dev., 10, 2117-2140, https://doi.org/10.5194/gmd-10-2117-2017, 2017 A new algorithm for the generation of very high-quality staggered unstructured grids for multi-resolution ocean and atmospheric modelling is described. Through use of unstructured triangulation and grid-optimisation techniques, it is shown that meshes satisfying a number of important a priori grid-quality constraints can be constructed. This new algorithm is expected to be of interest to both developers and users of unstructured general circulation models.

Description: Sensitivity Analysis of a Coupled Hydrodynamic-Vegetation Model Using the Effectively Subsampled Quadratures Method Tarandeep S. Kalra, Alfredo Aretxabaleta, Pranay Seshadri, Neil K. Ganju, and Alexis Beudin Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-107,2017 Manuscript under review for GMD (discussion: open, 0 comments) The manuscript details the sensitivity of vegetation properties that are input to a 3D submerged aquatic vegetation model within a coupled hydrodynamics and wave model. It describes a novel strategy to perform sensitivity analysis efficiently by using a combination of Effective Quadratures method and Sobol' indices. This method reduces the number of simulations to understand the sensitivity patterns and also quantifies the amount of sensitivity.

Description: Impacts of microtopographic snow-redistribution and lateral subsurface processes on hydrologic and thermal states in an Arctic polygonal ground ecosystem Gautam Bisht, William J. Riley, Haruko M. Wainwright, Baptiste Dafflon, Yuan Fengming, and Vladimir E. Romanovsky Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-71,2017 Manuscript under review for GMD (discussion: open, 0 comments) The land model integrated in the ACME Earth System Model (ESM) was extended to include snow redistribution (SR) and lateral subsurface hydrologic and thermal processes. Simulation results at a polygonal tundra site near Barrow, Alaska showed inclusion of SR resulted in a better agreement with observations. Excluding lateral subsurface processes had a small impact on mean states but a large overestimation of spatial variability in soil moisture and temperature.

Description: A single-column particle-resolved model for simulating the vertical distribution of aerosol mixing state: WRF-PartMC-MOSAIC-SCM v1.0 Jeffrey H. Curtis, Nicole Riemer, and Matthew West Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-112,2017 Manuscript under review for GMD (discussion: open, 0 comments) Traditional aerosol representations rely on simplifying assumptions regarding aerosol composition in order to reduce computational cost. This affects the estimate of macroscale properties of the atmosphere. In contrast, the WRF-PartMC-MOSAIC-SCM model, presented here, uses a particle-resolved aerosol representation. It is made feasible by the development of efficient numerical methods, and allows for the capturing of complex aerosol mixing states with altitude.

Description: DCMIP2016: A Review of Non-hydrostatic Dynamical Core Design and Intercomparison of Participating Models Paul A. Ullrich, Christiane Jablonowski, James Kent, Peter H. Lauritzen, Ramachandran Nair, Kevin A. Reed, Colin M. Zarzycki, David M. Hall, Don Dazlich, Ross Heikes, Celal Konor, David Randall, Thomas Dubos, Yann Meurdesoif, Xi Chen, Lucas Harris, Christian Kühnlein, Vivian Lee, Abdessamad Qaddouri, Claude Girard, Marco Giorgetta, Daniel Reinert, Joseph Klemp, Sang-Hun Park, William Skamarock, Hiroaki Miura, Tomoki Ohno, Ryuji Yoshida, Robert Walko, Alex Reinecke, and Kevin Viner Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-108,2017 Manuscript under review for GMD (discussion: open, 0 comments) Atmospheric dynamical cores are a fundamental component of global atmospheric modeling systems, and are responsible for capturing the dynamical behavior of the Earth's atmosphere. To better understand modern dynamical cores, this paper aims to provide a comprehensive review of eleven dynamical cores, drawn from modeling centers and groups that participated in the 2016 Dynamical Core Model Intercomparison Project (DCMIP) workshop and summer school.

Description: Plume-SPH 1.0: A three-dimensional, dusty-gas volcanic plume model based on smoothed particle hydrodynamics Zhixuan Cao, Abani Patra, Marcus Bursik, E. Bruce Pitman, and Matthew Jones Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-119,2017 Manuscript under review for GMD (discussion: open, 0 comments) Plume-SPH provides the first particle based simulation of volcanic plumes. Smooth particle hydrodynamics used here has several advantages over mesh based methods for multiphase free boundary flows like volcanic plumes. This tool will provide more accurate eruption source terms to users of Volcanic ash transport and dispersion models greatly improving volcanic ash forecasts.The Plume-SPH code incorporates several newly developed techniques in SPH needed multiphase compressible turbulent flow.

Description: Defining metrics of the Quasi-Biennial Oscillation in global climate models Verena Schenzinger, Scott Osprey, Lesley Gray, and Neal Butchart Geosci. Model Dev., 10, 2157-2168, https://doi.org/10.5194/gmd-10-2157-2017, 2017 The Quasi-Biennial Oscillation (QBO) is a pattern of winds in the equatorial stratosphere that has been observed for the past 60 years. It is thought to have long-range influences, e.g. on the Northern Hemisphere winter polar vortex and therefore Europe's winter weather. Since its period is about 2 years, being able to predict the QBO might also improve weather forecasting. Using a set of characteristic metrics, this paper examines how reliable current climate models are in simulating the QBO.

Description: A 4D-Var inversion system based on the icosahedral grid model (NICAM-TM 4D-Var v1.0) – Part 2: Optimization scheme and identical twin experiment of atmospheric CO 2 inversion Yosuke Niwa, Yosuke Fujii, Yousuke Sawa, Yosuke Iida, Akihiko Ito, Masaki Satoh, Ryoichi Imasu, Kazuhiro Tsuboi, Hidekazu Matsueda, and Nobuko Saigusa Geosci. Model Dev., 10, 2201-2219, https://doi.org/10.5194/gmd-10-2201-2017, 2017 A new 4D-Var inversion system based on the icosahedral grid model, NICAM, is introduced and tested. Adding to the offline forward and adjoint models, this study has introduced the optimization method of POpULar; it does not require difficult decomposition of a matrix that establishes the correlation among the prior flux errors. In identical twin experiments of atmospheric CO 2 inversion, the system successfully reproduces the spatiotemporal variations of the surface fluxes.

Description: rpe v5: an emulator for reduced floating-point precision in large numerical simulations Andrew Dawson and Peter D. Düben Geosci. Model Dev., 10, 2221-2230, https://doi.org/10.5194/gmd-10-2221-2017, 2017 Weather and climate models must become more efficient if they continue growing in complexity. One option for reducing computational cost is to reduce numerical precision. We present a tool that allows users to study how models perform with reduced numerical precision. The tool is applied to a geophysical use case where precision is heavily reduced while maintaining suitable accuracy. The tool can be applied to other models to determine whether they can be made more computationally efficient.

Description: Modeling regional air quality and climate: improving organic aerosol and aerosol activation processes in WRF/Chem version 3.7.1 Khairunnisa Yahya, Timothy Glotfelty, Kai Wang, Yang Zhang, and Athanasios Nenes Geosci. Model Dev., 10, 2333-2363, https://doi.org/10.5194/gmd-10-2333-2017, 2017 Air quality and climate influence each other through the uncertain processes of aerosol formation and cloud droplet activation. In this study, both processes are improved in the Weather, Research and Forecasting model with Chemistry (WRF/Chem) version 3.7.1. The existing Volatility Basis Set (VBS) treatments for organic aerosol (OA) formation in WRF/Chem are improved by considering the following: the secondary OA (SOA) formation from semi-volatile primary organic aerosol (POA), a semi-empirical formulation for the enthalpy of vaporization of SOA, and functionalization and fragmentation reactions for multiple generations of products from the oxidation of VOCs. Over the continental US, 2-month-long simulations (May to June 2010) are conducted and results are evaluated against surface and aircraft observations during the Nexus of Air Quality and Climate Change (CalNex) campaign. Among all the configurations considered, the best performance is found for the simulation with the 2005 Carbon Bond mechanism (CB05) and the VBS SOA module with semivolatile POA treatment, 25 % fragmentation, and the emissions of semi-volatile and intermediate volatile organic compounds being 3 times the original POA emissions. Among the three gas-phase mechanisms (CB05, CB6, and SAPRC07) used, CB05 gives the best performance for surface ozone and PM 2. 5 concentrations. Differences in SOA predictions are larger for the simulations with different VBS treatments (e.g., nonvolatile POA versus semivolatile POA) compared to the simulations with different gas-phase mechanisms. Compared to the simulation with CB05 and the default SOA module, the simulations with the VBS treatment improve cloud droplet number concentration (CDNC) predictions (normalized mean biases from −40.8 % to a range of −34.6 to −27.7 %), with large differences between CB05–CB6 and SAPRC07 due to large differences in their OH and HO 2 predictions. An advanced aerosol activation parameterization based on the Fountoukis and Nenes (2005) series reduces the large negative CDNC bias associated with the default Abdul Razzak and Ghan (2000) parameterization from −35.4 % to a range of −0.8 to 7.1 %. However, it increases the errors due to overpredictions of CDNC, mainly over the northeastern US. This work indicates a need to improve other aerosol–cloud–radiation processes in the model, such as the spatial distribution of aerosol optical depth and cloud condensation nuclei, in order to further improve CDNC predictions.

Description: STRAPS v1.0: evaluating a methodology for predicting electron impact ionisation mass spectra for the aerosol mass spectrometer David O. Topping, James Allan, M. Rami Alfarra, and Bernard Aumont Geosci. Model Dev., 10, 2365-2377, https://doi.org/10.5194/gmd-10-2365-2017, 2017 Our ability to model the chemical and thermodynamic processes that lead to secondary organic aerosol (SOA) formation is thought to be hampered by the complexity of the system. In this proof of concept study, the ability to train supervised methods to predict electron impact ionisation (EI) mass spectra for the AMS is evaluated to facilitate improved model evaluation. The study demonstrates the use of a methodology that would be improved with more training data and data from simple mixed systems.

Description: Source-receptor matrix calculation for deposited mass with the Lagrangian particle dispersion model FLEXPART v10.2 in backward mode Sabine Eckhardt, Massimo Cassiani, Nikolaos Evangeliou, Espen Sollum, Ignacio Pisso, and Andreas Stohl Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-131,2017 Manuscript under review for GMD (discussion: open, 0 comments) We extend the backward modelling technique in an existing model (FLEXPART), to substances deposited at the Earth's surface by wet scavenging and dry deposition. This means that for existing measurements of a substance in snow, ice cores or rain samples the source regions can be determined. This will help the interpretation of the measurement as well as gaining information of emission strength at the source of the deposited substance.

Description: Synthesizing long-term sea level rise projections – the MAGICC sea level model v2.0 Alexander Nauels, Malte Meinshausen, Matthias Mengel, Katja Lorbacher, and Tom M. L. Wigley Geosci. Model Dev., 10, 2495-2524, https://doi.org/10.5194/gmd-10-2495-2017, 2017 The MAGICC sea level model projects global sea level rise by emulating process-based estimates for all major sea level drivers and applying them to available climate scenarios and their extensions to 2300. The MAGICC sea level projections are well within the ranges of the fifth IPCC assessment report. Due to its efficient structure, this emulator is a powerful tool for exploring sea level uncertainties and investigating sea level responses for a wide range of climate mitigation pathways.

Description: A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5 Juno Hsu, Michael J. Prather, Philip Cameron-Smith, Alex Veidenbaum, and Alex Nicolau Geosci. Model Dev., 10, 2525-2545, https://doi.org/10.5194/gmd-10-2525-2017, 2017 Solar-J is a high-fidelity solar radiative transfer Fortran 90 code. It has been developed for consistently calculating both the photolysis rates of important chemical species and the heating rates of the atmosphere and the Earth's surface. Its spectral range spans from 177 nm to 12 microns. It can be easily dropped in as a module in global climate–chemistry models.

Description: The carbon cycle in the Australian Community Climate and Earth System Simulator (ACCESS-ESM1) – Part 1: Model description and pre-industrial simulation Rachel M. Law, Tilo Ziehn, Richard J. Matear, Andrew Lenton, Matthew A. Chamberlain, Lauren E. Stevens, Ying-Ping Wang, Jhan Srbinovsky, Daohua Bi, Hailin Yan, and Peter F. Vohralik Geosci. Model Dev., 10, 2567-2590, https://doi.org/10.5194/gmd-10-2567-2017, 2017 The paper describes a version of the Australian Community Climate and Earth System Simulator that has been enabled to simulate the carbon cycle, which is designated ACCESS-ESM1. The model performance for pre-industrial conditions is assessed and land and ocean carbon fluxes are found to be simulated realistically.

Description: A multi-diagnostic approach to cloud evaluation Keith D. Williams and Alejandro Bodas-Salcedo Geosci. Model Dev., 10, 2547-2566, https://doi.org/10.5194/gmd-10-2547-2017, 2017 The simulation of cloud is problematic for general circulation models. As clouds come in differing types, areal coverage, altitude and reflectivity, it is possible for a model to appear to perform well against a particular observational dataset through a compensation of errors. Here we evaluate a model's cloud simulation against a range of observational datasets, globally and across weather–climate timescales, in order to provide a comprehensive assessment.

Description: Development of an inorganic and organic aerosol model (Chimere2017 β v1.0): seasonal and spatial evaluation over Europe Florian Couvidat, Bertrand Bessagnet, Marta Garcia-Vivanco, Elsa Real, Laurent Menut, and Augustin Colette Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-120,2017 Manuscript under review for GMD (discussion: open, 0 comments) This paper includes the development of a new aerosol module in the air quality model Chimere to improve Particulate Matter (PM) simulation. The results of the model are compared to numerous measurements over Europe to evaluate the strengths and weaknesses of the model.

Description: AMM15: A new high resolution NEMO configuration for operational simulation of the European North West Shelf Jennifer A. Graham, Enda O’Dea, Jason Holt, Jeff Polton, Helene T. Hewitt, Rachel Furner, Karen Guihou, Ashley Brereton, Alex Arnold, Sarah Wakelin, Juan Manuel Castillo Sanchez, and C. Gabriela Mayorga Adame Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-127,2017 Manuscript under review for GMD (discussion: open, 0 comments) This paper describes the next generation ocean forecast model for the European NW Shelf, AMM15 (Atlantic Margin Model, 1.5 km resolution). The current forecast system has a resolution of 7 km. While this is sufficient to represent large-scale circulation, many dynamical features (such as eddies, frontal-jets and internal tides) can only begin to be resolved at O(1 km) resolution. Here we introduce AMM15, and demonstrate its ability to represent the mean state and variability of the region.

Description: Source apportionment and sensitivity analysis: two methodologies with two different purposes Alain Clappier, Claudio A. Belis, Denise Pernigotti, and Philippe Thunis Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-161,2017 Manuscript under review for GMD (discussion: open, 0 comments) This work demonstrates that when the relationship between emissions and concentrations is non-linear, sensitivity approaches, generally used for air quality planning are not suitable to retrieve source contributions and source apportionment methods are not appropriate to evaluate the impact of abatement strategies on air quality. A simple theoretical example is used highlighting differences and potential implications for policy.

Description: On the Predictability of Land Surface Fluxes from Meteorological Variables Ned Haughton, Gab Abramowitz, and Andy J. Pitman Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-153,2017 Manuscript under review for GMD (discussion: open, 0 comments) Previous studies indicate that fluxes of heat, water, and carbon between the land surface and atmosphere are substantially more predictable than the performance of the current crop of land surface models would indicate. This study uses simple empirical models to estimate the amount of useful information in meteorological forcings that is available for predicting land surface fluxes. These models can be used as benchmarks for land surface models, and may help identify areas ripe for improvement.

Description: A parameterisation for the co-condensation of semi-volatile organics into multiple aerosol particle modes Matthew Crooks, Paul Connolly, and Gordon McFiggans Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-123,2017 Manuscript under review for GMD (discussion: open, 0 comments) Clouds form when water condenses onto particles in the atmosphere and the size and chemical composition of these particles can have a large influence over how much water condenses and the subsequent formation of cloud. Additional gases exist in the atmosphere that can condense onto the aerosol particles and change their composition. We present a fast and efficient method of calculating the effect of atmospheric gases on the formation of cloud that can be used in climate and weather models.

Description: The iFlow modelling framework v2.4: a modular idealized process-based model for flow and transport in estuaries Yoeri M. Dijkstra, Ronald L. Brouwer, Henk M. Schuttelaars, and George P. Schramkowski Geosci. Model Dev., 10, 2691-2713, https://doi.org/10.5194/gmd-10-2691-2017, 2017 The iFlow modelling framework is a width-averaged model for the systematic analysis of the water motion and sediment transport processes in estuaries and tidal rivers. The distinctive solution method, a mathematical perturbation method, used in the model allows for identification of the effect of individual physical processes on the water motion and sediment transport and study of the sensitivity of these processes to model parameters. This distinction between processes provides a unique tool for interpreting and explaining hydrodynamic interactions and sediment trapping. iFlow also includes a large number of options to configure the model geometry and multiple choices of turbulence and salinity models. Additionally, the model contains auxiliary components, including one that facilitates easy and fast sensitivity studies. iFlow has a modular structure, which makes it easy to include, exclude or change individual model components, called modules. Depending on the required functionality for the application at hand, modules can be selected to construct anything from very simple quasi-linear models to rather complex models involving multiple non-linear interactions. This way, the model complexity can be adjusted to the application. Once the modules containing the required functionality are selected, the underlying model structure automatically ensures modules are called in the correct order. The model inserts iteration loops over groups of modules that are mutually dependent. iFlow also ensures a smooth coupling of modules using analytical and numerical solution methods. This way the model combines the speed and accuracy of analytical solutions with the versatility of numerical solution methods. In this paper we present the modular structure, solution method and two examples of the use of iFlow. In the examples we present two case studies, of the Yangtze and Scheldt rivers, demonstrating how iFlow facilitates the analysis of model results, the understanding of the underlying physics and the testing of parameter sensitivity. A comparison of the model results to measurements shows a good qualitative agreement. iFlow is written in Python and is available as open source code under the LGPL license.

Description: BRICK v0.2, a simple, accessible, and transparent model framework for climate and regional sea-level projections Tony E. Wong, Alexander M. R. Bakker, Kelsey Ruckert, Patrick Applegate, Aimée B. A. Slangen, and Klaus Keller Geosci. Model Dev., 10, 2741-2760, https://doi.org/10.5194/gmd-10-2741-2017, 2017 We present the Building blocks for Relevant Ice and Climate Knowledge (BRICK) model v0.2. BRICK is a model for hindcasting past and projecting future surface temperature and sea-level rise, resolving the sea-level contributions from glaciers and ice caps, the Greenland and Antarctic ice sheets, and thermal expansion. BRICK is specifically designed to support decision analyses through its transparency, and includes functionality to scale global sea-level estimates to regional projections.

Description: Coastal Modelling Environment version 1.0: a framework for integrating landform-specific component models in order to simulate decadal to centennial morphological changes on complex coasts Andrés Payo, David Favis-Mortlock, Mark Dickson, Jim W. Hall, Martin D. Hurst, Mike J. A. Walkden, Ian Townend, Matthew C. Ives, Robert J. Nicholls, and Michael A. Ellis Geosci. Model Dev., 10, 2715-2740, https://doi.org/10.5194/gmd-10-2715-2017, 2017 CoastalME is a generic modelling environment to simulate coastal landscape evolution on spatial scales of kms to tens of kms, over decadal to centennial timescales. The novelty is that it simulates coastal morphology evolution as a set of dynamically linked raster and geometrical objects. Geometrical objects are derived from the raster structure providing a library of coastal elements (e.g. shoreline) that are conventionally used for modelling coastal behaviour on the timescales of interest.

Description: Tiling soil textures for terrestrial ecosystem modelling via clustering analysis: a case study with CLASS-CTEM (version 2.1) Joe R. Melton, Reinel Sospedra-Alfonso, and Kelly E. McCusker Geosci. Model Dev., 10, 2761-2783, https://doi.org/10.5194/gmd-10-2761-2017, 2017 Climate models have large grid cells due to the computational cost of running these complex models. Within grid cells like these, the land surface can vary dramatically impacting the exchange of water, carbon, and energy between the atmosphere and land. We use a technique to determine natural clusters of high-resolution soil texture within large grid cells and use them as inputs to our model. We find relatively low sensitivity to soil texture changes except in very dry regions and peatlands.

Description: Revised mineral dust emissions in the atmospheric chemistry-climate model EMAC (based on MESSy 2.52) Klaus Klingmüller, Swen Metzger, Mohamed Abdelkader, Vlassis A. Karydis, Georgiy L. Stenchikov, Andrea Pozzer, and Jos Lelieveld Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-160,2017 Manuscript under review for GMD (discussion: open, 0 comments) More than one billion tons of mineral dust particles are raised into the atmosphere every year, which has a significant impact on climate, society and ecosystems. The location, time and amount of dust emissions depends on surface and wind conditions. In the atmospheric chemistry-climate model EMAC we have updated the relevant surface data and equations. Our validation shows that the updates substantially improve the agreement of model results and observations.

Description: Representing anthropogenic gross land use change, wood harvest and forest age dynamics in a global vegetation model ORCHIDEE-MICT (r4259) Chao Yue, Philippe Ciais, Sebastiaan Luyssaert, Wei Li, Matthew J. McGrath, Jinfeng Chang, and Shushi Peng Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-118,2017 Manuscript under review for GMD (discussion: open, 0 comments) Human alteration of land cover has caused CO 2 that's stored in forest biomass and soil to release to the atmosphere and thus contributed to global warming. Global vegetation models that are used to quantify such carbon emissions from land use change traditionally rarely include shifting cultivation and secondary forest age dynamics. In this study, we expanded one vegetation model to include these features. We found that carbon emissions from land use change are estimated to be smaller.

Description: Particle Swarm Optimization for Surface complexation with the PHREEQC geochemical model Ramadan Abdelaziz, Broder J. Merkel, Mauricio Zambrano-Bigiarini, and Sreejesh Nair Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-38,2017 Manuscript under review for GMD (discussion: open, 0 comments) The paper claims to presents a robust tool to estimate thermodynamic surface complexation parameter for the sorption of U(VI) onto quartz surface. The optimization package hydroPSO R is coupled with the geochemical speciation code PHREEQC. hydroPSO is used m parameter estimation tool for geochemical modeling with PHREEQC. Coupled hydroPSO with PHREEQC proved to be a robust tool to estimate surface complexation constants for uranium (VI) species on quartz.

Description: The method ADAMONT v1.0 for statistical adjustment of climate projections applicable to energy balance land surface models Deborah Verfaillie, Michel Déqué, Samuel Morin, and Matthieu Lafaysse Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-135,2017 Manuscript under review for GMD (discussion: open, 0 comments) We introduce the method ADAMONT v1.0 to adjust and disaggregate daily climate projections from a regional climate model against an observational dataset at hourly time resolution. The method uses a refined quantile mapping approach for statistical adjustment and an analogous method for sub-daily disaggregation. The method produces ultimately adjusted hourly time series of temperature, precipitation, wind speed, humidity, and short- and longwave radiation, which can in turn be used to force any energy balance land surface model. While the method is generic and can be employed on any appropriate observation time series, here we focus on the description and evaluation of the method in the French mountainous regions. The observational dataset used here is the SAFRAN meteorological reanalysis, which covers the entire French Alps split into 23 massifs, within which meteorological conditions are provided for several 300 m elevation bands. In order to evaluate the skills of the method itself, it is applied to the ALADIN-Climate v5 RCM using the ERA-Interim reanalysis as boundary conditions, for the time period from 1980 to 2010. Results of the ADAMONT method are compared to the SAFRAN reanalysis itself. Various evaluation criteria are used for temperature, precipitation, but also snow depth, which is computed by the SURFEX/ISBA-Crocus model using the meteorological driving data from either the adjusted RCM data, or the SAFRAN reanalysis itself. The evaluation addresses in particular the time transferability of the method (using various learning/application time periods), the impact of the RCM grid point selection procedure for each massif/altitude band configuration, and the inter-variable consistency of the adjusted meteorological data generated by the method. Results show that the performance of the method is satisfactory, with similar or even better evaluation metrics than alternative methods. However, results for air temperature are generally better than for precipitation. Results in terms of snow depth are satisfactory, which can be viewed as indicating a reasonably good inter-variable consistency of the meteorological data produced by the method. In terms of temporal transferability (evaluated over time periods of 15 years only), results depend on the learning period. In terms of RCM grid point selection technique, the use of a complex RCM grid points selection technique, taking into account horizontal but also altitudinal proximity to SAFRAN massif centre points/altitude couples, generally degrades evaluation metrics for high altitudes, compared to a simpler grid point selection method based on horizontal distance.

Description: The CarbonTracker Data Assimilation Shell (CTDAS) v1.0: implementation and global carbon balance 2001–2015 Ingrid T. van der Laan-Luijkx, Ivar R. van der Velde, Emma van der Veen, Aki Tsuruta, Karolina Stanislawska, Arne Babenhauserheide, Hui Fang Zhang, Yu Liu, Wei He, Huilin Chen, Kenneth A. Masarie, Maarten C. Krol, and Wouter Peters Geosci. Model Dev., 10, 2785-2800, https://doi.org/10.5194/gmd-10-2785-2017, 2017 The CarbonTracker Data Assimilation Shell (CTDAS) is the new modular implementation of the CarbonTracker Europe (CTE) data assimilation system. We present and document CTDAS and demonstrate its ability to estimate global carbon sources and sinks. We present the latest CTE results including the distribution of the carbon sinks over the hemispheres and between the land biosphere and the oceans. We show the versatility of CTDAS with an overview of the wide range of other applications.

Description: Compiled records of carbon isotopes in atmospheric CO 2 for historical simulations in CMIP6 Heather Graven, Colin E. Allison, David M. Etheridge, Samuel Hammer, Ralph F. Keeling, Ingeborg Levin, Harro A. J. Meijer, Mauro Rubino, Pieter P. Tans, Cathy M. Trudinger, Bruce H. Vaughn, and James W. C. White Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2017-166,2017 Manuscript under review for GMD (discussion: open, 0 comments) Modelling of carbon isotopes 13 C and 14 C in land and ocean components of Earth System Models provides opportunities for new insights and improved understanding of global carbon cycling, and for model evaluation. We compiled existing historical datasets to define the annual mean carbon isotopic composition of atmospheric CO 2 for 1850–2015 that can be used in CMIP6 and other modelling activities.

Description: Improvements to the WRF-Chem model for quasi-hemispheric simulations of aerosols and ozone in the Arctic Louis Marelle, Jean-Christophe Raut, Kathy S. Law, Larry K. Berg, Jerome D. Fast, Richard C. Easter, Manish Shrivastava, and Jennie L. Thomas Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-89,2017 Manuscript under review for GMD (discussion: open, 0 comments) We develop the WRF-Chem model to improve simulations of aerosols and ozone in the Arctic. Both species are important air pollutants and climate forcers, but models often struggle to reproduce observations in the Arctic. Our developments concern pollutant emissions, mixing, chemistry and removal, including processes related to snow and sea-ice. The effect of these changes are quantitatively validated against observations, showing significant improvements compared to the original model.

Description: The seamless and multi-model coupling between atmosphere, land, hydrology, ocean, waves and sea-ice models based on SURFEX surface model using OASIS3-MCT Aurore Voldoire, Bertrand Decharme, Joris Pianezze, Cindy Lebeaupin Brossier, Florence Sevault, Léo Seyfried, Valérie Garnier, Soline Bielli, Sophie Valcke, Antoinette Alias, Mickael Accensi, Fabrice Ardhuin, Marie-Noëlle Bouin, Véronique Ducrocq, Stéphanie Faroux, Hervé Giordani, Fabien Léger, Patrick Marsaleix, Romain Raynaud, Jean-Luc Redelsperger, Evelyne Richard, and Sébastien Riette Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-91,2017 Manuscript under review for GMD (discussion: open, 0 comments) This study presents the principles of the new coupling interface based on the SURFEX multi-surface model and the OASIS3-MCT coupler. As SURFEX can be plugged into several atmospheric models, it can be used in a wide range of applications, from global and regional coupled climate systems to high-resolution Numerical Weather Prediction systems or very fine scale systems dedicated to process studies. The objective of this development is to build and share a common structure for all these applications for the atmosphere-surface coupling, between atmospheric models and ocean, ice, hydrology, and wave models. The numerical and physical principles of the SURFEX interface between the different component models are described, and the different coupled systems into which the SURFEX OASIS3-MCT-based coupling interface is already applied are presented.

Description: Curriculum Vitae of the LOTOS-EUROS (v2.0) chemistry transport model Astrid M. M. Manders, Peter J. H. Builtjes, Lyana Curier, Hugo A. C. Denier van der Gon, Carlijn Hendriks, Sander Jonkers, Richard Kranenburg, Jeroen Kuenen, Arjo J. Segers, Renske M. A. Timmermans, Antoon Visschedijk, Roy J. Wichink Kruit, W. Addo J. Van Pul, Ferd J. Sauter, Eric van der Swaluw, Daan P. J. Swart, John Douros, Henk Eskes, Erik van Meijgaard, Bert van Ulft, Peter van Velthoven, Sabine Banzhaf, Andrea Mues, Rainer Stern, Guangliang Fu, Sha Lu, Arnold Heemink, Nils van Velzen, and Martijn Schaap Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-88,2017 Manuscript under review for GMD (discussion: open, 0 comments) The regional-scale air quality model LOTOS-EUROS has been developed by a consortium of Dutch institutes. Recently, version 2.0 of the model was released as an open source version. Next to a technical description and model evaluation for 2012, this paper presents the model developments in context of the history of air quality modelling and provides an outlook for future directions. Also key and innovative applications of LOTOS-EUROS are highlighted.

Description: Variational assimilation of IASI SO 2 plume height and total column retrievals in the 2010 eruption of Eyjafjallajökull using the SILAM v5.3 chemistry transport model Julius Vira, Elisa Carboni, Roy G. Grainger, and Mikhail Sofiev Geosci. Model Dev., 10, 1985-2008, doi:10.5194/gmd-10-1985-2017, 2017 The vertical and temporal distributions of sulfur dioxide emissions during the 2010 eruption of Eyjafjallajökull were reconstructed by combining data from the IASI satellite instrument with a dispersion model. Unlike in previous studies, both column density (the total amount above a given point) and the plume height were derived from the satellite data. This resulted in more accurate simulated vertical distributions for the times when the emission was not constrained by the column densities.

Description: Vorticity-divergence semi-Lagrangian global atmospheric model SL-AV20: dynamical core Mikhail Tolstykh, Vladimir Shashkin, Rostislav Fadeev, and Gordey Goyman Geosci. Model Dev., 10, 1961-1983, doi:10.5194/gmd-10-1961-2017, 2017 We present the hydrostatic dynamical core of the SL-AV20 global atmosphere model used for operational numerical weather prediction in Russia. The article describes model design, particularly vorticity-divergence formulation combined with the use of an unstaggerred grid. The model has an option to use a reduced latitude-longitude grid. The results for standard tests agree well with reference solutions.

Description: Correct boundary conditions for DNS models of nonlinear acoustic-gravity waves forced by atmospheric pressure variations Yuliya Kurdyaeva, Sergey Kshevetskii, Nikolay Gavrilov, and Sergey Kulichkov Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-76,2017 Manuscript under review for GMD (discussion: open, 0 comments) Various meteorological phenomena generate acoustic-gravity waves in the atmosphere and cause wave variations of atmospheric pressure. There are networks of microbarographs, which record pressure variations on the Earth's surface. The hydrodynamic problem of propagation of waves in the atmosphere from pressure variations on the Earth's surface is formulated. The problem wellposedness is proved. A supercomputer program for simulation of waves from pressure variations is developed and applied.

Description: Exploring precipitation pattern scaling methodologies and robustness among CMIP5 models Ben Kravitz, Cary Lynch, Corinne Hartin, and Ben Bond-Lamberty Geosci. Model Dev., 10, 1889-1902, doi:10.5194/gmd-10-1889-2017, 2017 Pattern scaling is a way of approximating regional changes without needing to run a full, complex global climate model. We compare two methods of pattern scaling for precipitation and evaluate which methods is better in particular circumstances. We also decompose precipitation into a CO 2 portion and a non-CO 2 portion. The methodologies discussed in this paper can help provide precipitation fields for other models for a wide variety of scenarios of future climate change.

Description: Multivariable Integrated Evaluation of Model Performance with the Vector Field Evaluation Diagram Zhongfeng Xu, Ying Han, and Congbin Fu Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-95,2017 Manuscript under review for GMD (discussion: open, 0 comments) The paper develops a multivariable integrated evaluation (MVIE) method to evaluating the overall performance of a climate model in simulating multiple fields. MVIE takes multiple statistics of multivariable into account and is expected to provide a more accurate and comprehensive evaluation of model performance. Moreover, a multivariable integrated evaluation index (MIEI) is also developed to concisely summarize model performance and facilitate multi-model intercomparison.

Description: Evaluation of high-resolution GRAMM/GRAL NO x simulations over the city of Zurich, Switzerland Antoine Berchet, Katrin Zink, Dietmar Oettl, Jürg Brunner, Lukas Emmenegger, and Dominik Brunner Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-102,2017 Manuscript under review for GMD (discussion: open, 0 comments) Hourly NO x concentrations were simulated for the city of Zurich, Switzerland, at 10 m resolution for the years 2013–2014. The simulations were generated with the nested mesoscale meteorology and microscale dispersion model system GRAMM/GRAL (versions v15.12/v14.8) by applying a catalogue-based approach. This approach was specifically designed to enable long-term city-wide building-resolving simulations with affordable computation costs. It relies on a discrete set of possible weather situations and corresponding steady-state flow and dispersion patterns that are pre-computed and then matched hourly with actual meteorological observations. The modelling system was comprehensively evaluated using eight sites continuously monitoring NO x concentrations and 65 passive samplers measuring NO 2 concentrations on a 2-weekly basis all over the city. The system was demonstrated to fulfil the European Commission standards for air pollution modelling at nearly all sites. The average spatial distribution was very well represented, despite a general tendency to overestimating the observed concentrations, possibly due to a crude representation of traffic-induced turbulence. The temporal variability of concentrations explained by varying emissions and weather situations was accurately reproduced on different time scales. The seasonal cycle of concentrations, mostly driven by stronger vertical dispersion in summer than in winter, was very well captured in the two year simulation period. Short-term events, such as episodes of particularly high and low concentrations, were detected in most cases by the system, although some unrealistic pollution peaks were occasionally generated, pointing at some limitations of the steady-state approximation. The different patterns of the diurnal cycle of concentrations observed in the city were generally well captured as well. The evaluation confirmed the adequacy of the catalogue-based approach in the context of city scale air pollution modelling. The ability to reproduce not only the spatial gradients but also the hourly temporal variability over multiple years makes the model system particularly suitable for investigating individualized air pollution exposure in the city.

Description: Carbon–nitrogen interactions in idealized simulations with JSBACH (version 3.10) Daniel S. Goll, Alexander J. Winkler, Thomas Raddatz, Ning Dong, Ian Colin Prentice, Philippe Ciais, and Victor Brovkin Geosci. Model Dev., 10, 2009-2030, doi:10.5194/gmd-10-2009-2017, 2017 The response of soil organic carbon decomposition to warming and the interactions between nitrogen and carbon cycling affect the feedbacks between the land carbon cycle and the climate. In the model JSBACH carbon–nitrogen interactions have only a small effect on the feedbacks, whereas modifications of soil organic carbon decomposition have a large effect. The carbon cycle in the improved model is more resilient to climatic changes than in previous version of the model.

Description: A non-linear Granger-causality framework to investigate climate–vegetation dynamics Christina Papagiannopoulou, Diego G. Miralles, Stijn Decubber, Matthias Demuzere, Niko E. C. Verhoest, Wouter A. Dorigo, and Willem Waegeman Geosci. Model Dev., 10, 1945-1960, doi:10.5194/gmd-10-1945-2017, 2017 Global satellite observations provide a means to unravel the influence of climate on vegetation. Common statistical methods used to study the relationships between climate and vegetation are often too simplistic to capture the complexity of these relationships. Here, we present a novel causality framework that includes data fusion from various databases, time series decomposition, and machine learning techniques. Results highlight the highly non-linear nature of climate–vegetation interactions.

Description: Studying the Impact of Radioactive Charging on the Microphysical Evolution and Transport of Radioactive Aerosols with the TOMAS-RC v1 framework Petros Vasilakos, Yong-Ηa Kim, Jeffrey R. Pierce, Sotira Yiacoumi, Costas Tsouris, and Athanasios Nenes Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-96,2017 Manuscript under review for GMD (discussion: open, 0 comments) Radioactive charging can significantly impact the way radioactive aerosols behave, and as a result their lifetime, but such effects are neglected in predictive model studies of radioactive plumes. We extend a well-established model that simulates the evolution of atmospheric particulate matter to account for radioactive charging effects in an accurate and computationally efficient way. It is shown that radioactivity can strongly impact the deposition patterns of aerosol.

Description: GLEAM v3: satellite-based land evaporation and root-zone soil moisture Brecht Martens, Diego G. Miralles, Hans Lievens, Robin van der Schalie, Richard A. M. de Jeu, Diego Fernández-Prieto, Hylke E. Beck, Wouter A. Dorigo, and Niko E. C. Verhoest Geosci. Model Dev., 10, 1903-1925, doi:10.5194/gmd-10-1903-2017, 2017 Terrestrial evaporation is a key component of the hydrological cycle and reliable data sets of this variable are of major importance. The Global Land Evaporation Amsterdam Model (GLEAM, www.GLEAM.eu ) is a set of algorithms which estimates evaporation based on satellite observations. The third version of GLEAM, presented in this study, includes an improved parameterization of different model components. As a result, the accuracy of the GLEAM data sets has been improved upon previous versions.

Description: The operational eEMEP model version 10.4 for volcanic SO 2 and ash forecasting Birthe M. Steensen, Michael Schulz, Peter Wind, Álvaro M. Valdebenito, and Hilde Fagerli Geosci. Model Dev., 10, 1927-1943, doi:10.5194/gmd-10-1927-2017, 2017 The operational emergency version of the EMEP MSC-W model for dispersion calculations of volcanic SO 2 and ash is described. Additions and changes to the standard EMEP MSC-W are presented. Grid resolution dependencies for meteorological data and numerical diffusion are studied by investigating model results driven by ensemble meteorological data for volcanic SO 2 emissions. The vertical ash layer sensitivity on gravitational settling is evaluated by comparing model results to lidar observations.

Description: Calibrating a wetland methane emission model with hierarchical modeling and adaptive MCMC Jouni Susiluoto, Maarit Raivonen, Leif Backman, Marko Laine, Jarmo Mäkelä, Olli Peltola, Timo Vesala, and Tuula Aalto Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-66,2017 Manuscript under review for GMD (discussion: open, 0 comments) Methane is an important greenhouse gas and methane emissions from wetlands contribute to the warming of the climate. Wetland methane emissions are also difficult to estimate. We analyze the functioning and performance of a wetland emission computer model with mathematical algorithms and data from a wetland in Southern Finland. The analysis provides insight into how wetland emission modeling can be improved and how uncertainties in the emission estimates can be reduced in future studies.

Description: Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1 K. Wyat Appel, Sergey L. Napelenok, Kristen M. Foley, Havala O. T. Pye, Christian Hogrefe, Deborah J. Luecken, Jesse O. Bash, Shawn J. Roselle, Jonathan E. Pleim, Hosein Foroutan, William T. Hutzell, George A. Pouliot, Golam Sarwar, Kathleen M. Fahey, Brett Gantt, Robert C. Gilliam, Nicholas K. Heath, Daiwen Kang, Rohit Mathur, Donna B. Schwede, Tanya L. Spero, David C. Wong, and Jeffrey O. Young Geosci. Model Dev., 10, 1703-1732, doi:10.5194/gmd-10-1703-2017, 2017 The Community Multiscale Air Quality (CMAQ) model is a comprehensive multipollutant air quality modeling system. The CMAQ model is used extensively throughout the world to simulate air pollutants for many purposes, including regulatory and air quality forecasting applications. This work describes the scientific updates made to the latest version of the CMAQ modeling system (CMAQv5.1) and presents an evaluation of the new model against observations and results from the previous model version.

Description: The relationship between intraseasonal tropical variability and ENSO simulated by the CMIP5 Tatiana Matveeva and Daria Gushchina Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-92,2017 Manuscript under review for GMD (discussion: open, 0 comments) Predicting El Niño both in current condition and for the next century is a key societal need. Intraseasonal atmosphere disturbances(ITV) plays an important role in triggering of El Niño, El Niño-ITV relationship may change in the future climate. The purpose of this study is to select the models the most skilful in simulation of ITV-El Niño relationship and thus promising for investigation of El Niño mechanism under global warming. CMCC-CM, MIROC5 and INMCM4 models of CMIP5 project were selected.

Description: The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue – metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models Yoko Tsushima, Florent Brient, Stephen A. Klein, Dimitra Konsta, Christine Nam, Xin Qu, Keith D. Williams, Steven C. Sherwood, Kentaroh Suzuki, and Mark D. Zelinka Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-69,2017 Manuscript under review for GMD (discussion: open, 0 comments) Cloud feedback is the largest uncertainty associated with estimates of climate sensitivity. Diagnostics have been developed to evaluate cloud processes in climate models. For this understanding to be reflected in better estimates of cloud feedbacks it is vital to continue to develop such tools and to exploit them fully during the model development process. Code repositories have been created to store and document the programs which will allow climate modellers to compute these diagnostics.

Description: Ellipsoids (v1.0): 3D Magnetic modelling of ellipsoidal bodies Diego Takahashi Tomazella and Vanderlei C. Oliveira Jr. Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-44,2017 Manuscript under review for GMD (discussion: open, 0 comments) Ellipsoids are the only bodies for which the self-demagnetization can be treated analytically. this property is particularly useful for modelling compact orebodies having high susceptibility. Here, we present a review of the magnetic modelling of ellipsoids, propose an alternative way of determining the isotropic susceptibility above which the self-demagnetization must be taken into consideration, as well as provide a set of routines to model the magnetic field produced by ellipsoids.

Description: CHROTRAN 1.0: A mathematical and computational model for in situ heavy metal remediation in heterogeneous aquifers Scott K. Hansen, Sachin Pandey, Satish Karra, and Velimir V. Vesselinov Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-51,2017 Manuscript under review for GMD (discussion: open, 0 comments) Groundwater contamination by heavy metals is a critical environmental problem for which in situ remediation is frequently the only viable treatment option. We developed a computer model for simulating such interventions, which includes custom reaction kinetics equations for the coupled interactions between the metal, the existing microbial population, and a number of possible chemical amendments. We describe installation and usage and present two instructive example simulations.

Description: Description and Validation of the Simple, Efficient, Dynamic, Global, Ecological Simulator (SEDGES v.1.0) Pablo Paiewonsky and Oliver Elison Timm Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-75,2017 Manuscript under review for GMD (discussion: open, 0 comments) This paper presents a simple vegetation model for use as part of a climate or Earth system model. The model equations and their derivations are presented. We evaluate the model's performance offline using near-present-day real-world datasets and deem it to be satisfactory. The model is useful because it is fast, easy to understand, and general in its formulations. It was developed to better simulate climate-vegetation feedbacks for answering paleoclimate research questions.

Description: Tuning without over-tuning: parametric uncertainty quantification for the NEMO ocean model Daniel B. Williamson, Adam T. Blaker, and Bablu Sinha Geosci. Model Dev., 10, 1789-1816, doi:10.5194/gmd-10-1789-2017, 2017 We present a method from the statistical science literature to assist in the tuning of global climate models submitted to CMIP. We apply the method to the NEMO ocean model and find choices of its free parameters that lead to improved representations of depth integrated global mean temperature and salinity. We argue against automatic tuning procedures that involve optimising certain outputs of a model and explain why our method avoids common difficulties with/arguments against automatic tuning.

Description: Nine time steps: ultra-fast statistical consistency testing of the Community Earth System Model (pyCECT v3.0) Daniel J. Milroy, Allison H. Baker, Dorit M. Hammerling, and Elizabeth R. Jessup Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-49,2017 Manuscript under review for GMD (discussion: open, 0 comments) The Community Earth System Model Ensemble Consistency Test (CESM-ECT) suite was developed as an alternative to requiring bitwise identical output for quality assurance. We extend the CESM-ECT suite with an inexpensive and robust test for ensemble consistency that is applied to Community Atmospheric Model output after only nine model time steps. The new ultra-fast test facilitates CESM development, porting, and optimization efforts, and complements the original suite of tools.

Description: Improved method for linear carbon monoxide simulation and source attribution in atmospheric chemistry models illustrated using GEOS-Chem v9 Jenny A. Fisher, Lee T. Murray, Dylan B. A. Jones, and Nicholas M. Deutscher Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-94,2017 Manuscript under review for GMD (discussion: open, 0 comments) Carbon monoxide (CO) simulation in atmospheric chemistry models is used for source-receptor analysis, emission inversion, and interpretation of observations. We introduce a major update to CO simulation in the GEOS-Chem chemical transport model that removes fundamental inconsistencies relative to the standard model, resolving biases of more than 100 ppb and errors in vertical structure. We also add source-tagging of secondary CO and demonstrate it provides added value in low-emission regions.

Description: TempestExtremes: a framework for scale-insensitive pointwise feature tracking on unstructured grids Paul A. Ullrich and Colin M. Zarzycki Geosci. Model Dev., 10, 1069-1090, doi:10.5194/gmd-10-1069-2017, 2017 Automated pointwise feature tracking is used for objective identification and tracking of meteorological features, such as extratropical cyclones, tropical cyclones and tropical easterly waves, and has emerged as an important and desirable data-processing capability in climate science. In the interest of exploring tracking functionality, this paper introduces a framework for the development of robust tracking algorithms that is useful for intercomparison and optimization of tracking schemes.

Description: Update of the SWIFT model for polar stratospheric ozone loss (SWIFT version 2) Ingo Wohltmann, Ralph Lehmann, and Markus Rex Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-19,2017 Manuscript under review for GMD (discussion: open, 0 comments) The SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in Global Climate Models (GCMs) and Earth System Models (ESMs) to enable the simulation of interactions between the ozone layer and climate. So far, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. SWIFT is based on a set of coupled differential equations, which simulate the polar vortex averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O 3 , active chlorine (ClO x ), HCl, ClONO 2 and HNO 3 . The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at single processes and an independent validation of the different parameterizations for the single processes contained in the differential equations. The training of the original SWIFT model was based on fitting complete model runs to satellite observations and did not allow this. A revised formulation of the system of differential equations is developed, which closely fits vortex averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the SWIFT model are purely chemical rates of change in the new version, while the rates of change in the original SWIFT version included a transport effect caused by the original training on satellite data. Hence, the new version allows for an implementation into climate models in combination with an existing stratospheric transport scheme. Finally, the model is now formulated on several vertical levels encompassing the vertical range in which polar ozone depletion is observed. The results of the SWIFT model are validated with independent MLS satellite observations and the results of the original detailed chemistry model of ATLAS.

Description: The SUPECA kinetics for scaling redox reactions in networks of mixed substrates and consumers and an example application to aerobic soil respiration Jinyun Tang and William J. Riley Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-46,2017 Manuscript under review for GMD (discussion: open, 0 comments) We proposed the SUPECA kinetics to scale from single biogeochemical reactions to a network of mixed substrates and consumers. The framework for the first time integrates single substrate reactions, two-substrate reactions and mineral surface sorption reactions as a scaling consistent network, which is an essential feature of nature. This new theory is theoretically solid and outperforms existing theories. The test with aerobic soil respiration showed its strengths for pragmatic applications.

Description: An Operational Thermodynamic-Dynamic Model for the Coastal Labrador Sea Ice Melt Season Ian D. Turnbull and Rocky S. Taylor Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-39,2017 Manuscript under review for GMD (discussion: open, 0 comments) We developed a model to forecast the timing of the seasonal break-up of coastal Labrador land-fast ice in order to aid offshore operators in the region with their planning and decision-making process. The model additionally provides shorter-term (several days) ice drift forecasts for the operators. Our model can forecast the break-up of the land-fast ice at specific locations along the Labrador coast accurately to within hours to days when initialized up to a month in advance.

Description: Assimilation of MODIS Dark Target and Deep Blue observations in the dust aerosol component of NMMB-MONARCH version 1.0 Enza Di Tomaso, Nick A. J. Schutgens, Oriol Jorba, and Carlos Pérez García-Pando Geosci. Model Dev., 10, 1107-1129, doi:10.5194/gmd-10-1107-2017, 2017 A data assimilation capability has been built for a chemical weather prediction system, with a focus on mineral dust. Before this work, dust was produced uniquely from model estimated emissions. As emissions are recognized as a major factor limiting the accuracy of dust modelling, satellite observations have been used to improve the description of the atmospheric dust load, with a significant impact on dust forecast from assimilating observations particularly relevant for dust applications.

Description: Neodymium isotopes in the ocean model of the Community Earth System Model (CESM1.3) Sifan Gu, Zhengyu Liu, Alexandra Jahn, Johannes Rempfer, Jiaxu Zhang, and Fortunat Joos Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-40,2017 Manuscript under review for GMD (discussion: open, 0 comments) This paper is the documentation of the implementation of neodymium (Nd) isotopes in the ocean model of CESM. Our model can simulate both Nd concentration and Nd isotope ratio in good agreement with observations. Our Nd-enabled ocean model makes it possible for direct model-data comparison in paleoceanographic studies, which can help to resolve some uncertainties and controversies in our understanding of past ocean evolution. Therefore, our model provides a useful tool for paleoclimate studies.

Description: A new urban surface model integrated in the large-eddy simulation model PALM Jaroslav Resler, Pavel Krč, Michal Belda, Pavel Juruš, Nina Benešová, Jan Lopata, Ondřej Vlček, Daša Damašková, Kryštof Eben, Přemysl Derbek, Björn Maronga, and Farah Kanani-Sühring Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-61,2017 Manuscript under review for GMD (discussion: open, 0 comments) A realistic numerical modelling of urban climate still poses a serious challenge. The paper describes a new Urban Surface Model (USM), integrated into the large-eddy simulation model PALM. The USM covers the most important urban canopy processes (e.g. radiation, energy balance on surfaces, thermal diffusion). The model was tested in the real conditions of a city and shows good agreement with observations. The USM is optimized for high-performance computing systems and is freely available.

Description: Numerical simulations of glacier evolution performed using flow-line models of varying complexity Antonija Rimac, Sharon van Geffen, and Johannes Oerlemans Geosci. Model Dev. Discuss., doi:10.5194/gmd-2017-67,2017 Manuscript under review for GMD (discussion: open, 0 comments) The main aim of this paper is to use explicit glacier flow-line models of a different complexity to analyse the glacier length and volume evolution, and to disentangle climatic signals from geometric effects. We compare length and volume evolution of a synthetically designed glaciers simulated using Full-Stokes model based on Elmer/Ice code with the results obtained using SIA model.