Analysis of the impact of inhomogeneous emissions in the Operational Street Pollution Model (OSPM)
Summary: Semi-parameterised street canyon models are popular due to their speed and low input requirements. One often-used assumption is that emissions are homogeneously distributed in the entire length and width of the street. It is thus the aim of the present study to analyse the impact of this assumption by implementing an inhomogeneous emission geometry scheme and validating it. The results show an improved performance, however, confounded by challenges in estimating the emissions accurately.
Geosci. Model Dev., 8, 3231-3245, doi:10.5194/gmd-8-3231-2015, 2015
An open and extensible framework for spatially explicit land use change modelling: the lulcc R package
Summary: The contribution of lulcc is to provide a free and open-source framework for land use change modelling. The software, which is provided as an R package, addresses problems associated with the current paradigm of closed-source, specialised land use change modelling software which disrupt the scientific process. It is an attempt to move the discipline towards open and transparent science and to ensure land use change models are accessible to scientists working across the geosciences.
Geosci. Model Dev., 8, 3215-3229, doi:10.5194/gmd-8-3215-2015, 2015
A new sub-grid surface mass balance and flux model for continental-scale ice sheet modelling: testing and last glacial cycle
Summary: A long-term challenge for any model of complex large-scale processes is accounting for the impact of unresolved sub-grid (SG) processes. We quantify the impact of SG mass-balance and ice fluxes on glacial cycle ensemble results for North America. We find no easy solutions to accurately capture these impacts. We show that SG process representation and associated parametric uncertainties can have significant impact on coarse resolution model results for glacial cycle ice sheet evolution.
Geosci. Model Dev., 8, 3199-3213, doi:10.5194/gmd-8-3199-2015, 2015
Simulation of atmospheric N2O with GEOS-Chem and its adjoint: evaluation of observational constraints
Summary: This paper introduces a new inversion framework for N2O using GEOS-Chem and its adjoint, which we employed in a series of observing system simulation experiments to evaluate the source and sink constraints provided by surface and aircraft-based N2O measurements. We also applied a new approach for estimating a posteriori uncertainty for high-dimensional inversions, and used it to quantify the spatial and temporal resolution of N2O emission constraints achieved with the current observing network.
Geosci. Model Dev., 8, 3179-3198, doi:10.5194/gmd-8-3179-2015, 2015
S2P3-R (v1.0): a framework for efficient regional modelling of physical and biological structures and processes in shelf seas
Summary: Our relatively shallow shelf seas are warmed at the surface in spring and summer, while strong tidal currents act to mix away the surface warmth. These competing effects strongly influence the conditions for seasonal growth of the phytoplankton that support marine food webs. We have developed a versatile framework for fast computer modelling of shelf seas, to explore seasonal and year-to-year variations of warming and plankton productivity, tested against observations in different regions.
Geosci. Model Dev., 8, 3163-3178, doi:10.5194/gmd-8-3163-2015, 2015
Development of a chlorine chemistry module for the Master Chemical Mechanism
Summary: A detailed chemical mechanism including 205 reactions is developed for use in the Master Chemical Mechanism. With this new chlorine mechanism, it was found that the nocturnal formation of ClNO2 has high potential to perturb the next day's atmospheric photochemistry, by enhancing the radical production and cycling, VOC oxidation and O3 formation, in the polluted coastal environments.
Geosci. Model Dev., 8, 3151-3162, doi:10.5194/gmd-8-3151-2015, 2015
DYNAMICO-1.0, an icosahedral hydrostatic dynamical core designed for consistency and versatility
Summary: The design of the icosahedral atmospheric dynamical core DYNAMICO is presented. The key contribution is to combine a strict separatation of kinematics from dynamics to a Hamiltonian formulation of the equations of motion in a non-Eulerian vertical coordinate to achieve energetic consistency. This approach allows for a unified treatment of various equations of motion: multi-layer shallow-water equations and hydrostatic primitive equations.
Geosci. Model Dev., 8, 3131-3150, doi:10.5194/gmd-8-3131-2015, 2015
Increasing vertical mixing to reduce Southern Ocean deep convection in NEMO3.4
Summary: Most ocean models, including NEMO, have unrealistic Southern Ocean deep convection. That is, through extensive areas of the Southern Ocean, they exhibit convection from the surface of the ocean to the sea floor. We find this convection to be an issue as it impacts the whole ocean circulation, notably strengthening the Antarctic Circumpolar Current. Using sensitivity experiments, we show that counter-intuitively the vertical mixing needs to be enhanced to reduce this spurious convection.
Geosci. Model Dev., 8, 3119-3130, doi:10.5194/gmd-8-3119-2015, 2015
Assessment of valley cold pools and clouds in a very high-resolution numerical weather prediction model
Summary: The formation of cold air pools in valleys under stable conditions represents an important challenge for numerical weather prediction (NWP). In this study a two-month cold pool simulation is presented using a high-resolution NWP model. Results are compared to observations and assumptions made in the cloud parametrization scheme about the sub-grid variability of humidity are shown to dominate model bias. Our results show that this is a key area for very high resolution modelling development.
Geosci. Model Dev., 8, 3105-3117, doi:10.5194/gmd-8-3105-2015, 2015
ECCO version 4: an integrated framework for non-linear inverse modeling and global ocean state estimation
Summary: The ECCO v4 non-linear inverse modeling framework and its reference solution are made publicly available. The inverse estimate of ocean physics and atmospheric forcing yields a dynamically consistent and global state estimate without unidentified sources of heat and salt that closely fits in situ and satellite data. Any user can reproduce it accurately. Parametric and external model uncertainties are of comparable magnitudes and generally exceed structural model uncertainties.
Geosci. Model Dev., 8, 3071-3104, doi:10.5194/gmd-8-3071-2015, 2015
A soil diffusion–reaction model for surface COS flux: COSSM v1
Summary: We report a soil COS flux model that is the first to resolve both vertical transport and microbial sources and sinks in soil and litter. By evaluation with field data, we show that the model can reproduce observed daily and long-term variations of soil COS flux. We also demonstrate that diffusion is important in controlling the flux, by limiting the COS available for soil uptake when there is strong litter uptake and modulating the water content dependence of soil uptake.
Geosci. Model Dev., 8, 3055-3070, doi:10.5194/gmd-8-3055-2015, 2015
Impact of climate, vegetation, soil and crop management variables on multi-year ISBA-A-gs simulations of evapotranspiration over a Mediterranean crop site
Summary: This paper investigates the impacts of uncertainties in the climate, the vegetation dynamic, the soil properties and the cropland management on the simulation of evapotranspiration from the ISBA-A-gs land surface model over a 12-year Mediterranean crop succession. It mainly shows that errors in the soil parameters and the lack of irrigation in the simulation have the largest influence on evapotranspiration compared to the uncertainties in the climate and the vegetation dynamic.
Geosci. Model Dev., 8, 3033-3053, doi:10.5194/gmd-8-3033-2015, 2015
Using satellite-based estimates of evapotranspiration and groundwater changes to determine anthropogenic water fluxes in land surface models
Summary: Current land surface models (LSMs) poorly represent irrigation impacts on regional hydrology. Approaches to include irrigation in LSMs are based on either potentially outdated irrigation inventory data or soil moisture curves that are not constrained by regional water balances. We use satellite remote sensing of actual ET and groundwater depletion to develop recent estimates of regional irrigation data. Remote sensing parameterizations of irrigation improve model performance.
Geosci. Model Dev., 8, 3021-3031, doi:10.5194/gmd-8-3021-2015, 2015
A 3-D RBF-FD solver for modeling the atmospheric global electric circuit with topography (GEC-RBFFD v1.0)
Geosci. Model Dev., 8, 3007-3020, doi:10.5194/gmd-8-3007-2015, 2015
The Louvain-La-Neuve sea ice model LIM3.6: global and regional capabilities
Summary: LIM3.6 presented in this paper is the last release of the Louvain-la-Neuve sea ice model, and will be used for the next climate model intercomparison project (CMIP6). The model's robustness, versatility and sophistication have been improved.
Geosci. Model Dev., 8, 2991-3005, doi:10.5194/gmd-8-2991-2015, 2015
Development of efficient GPU parallelization of WRF Yonsei University planetary boundary layer scheme
Summary: To expedite weather research and prediction, we have put tremendous effort into developing an accelerated implementation of the entire WRF model using GPU massive parallel computing architecture. This paper presents our efficient GPU-based design on WRF YSU PBL scheme. Using one NVIDIA Tesla K40 GPU, the GPU-based YSU PBL scheme achieves a speedup of 193x with respect to its runtime on 1 CPU core. We can even boost the speedup to 360x with respect to 1 CPU core as two K40 GPUs are applied.
Geosci. Model Dev., 8, 2977-2990, doi:10.5194/gmd-8-2977-2015, 2015
Calculations of the integral invariant coordinates I and L* in the magnetosphere and mapping of the regions where I is conserved, using a particle tracer (ptr3D v2.0), LANL*, SPENVIS, and IRBEM
Summary: The 2nd & 3rd adiabatic invariants (in particular their proxies I & L*) are commonly used to characterize charged particle motion in a magnetic field. However care should be taken when calculating them, as the assumption of their conservation is not valid everywhere in the Earth’s magnetosphere. In this paper we compare calculations of I and L* using LANLstar, SPENVIS, IRBEM and a 3D particle tracer, and we map the areas in the Earth’s magnetosphere where I & L* can be assumed to be conserved.
Geosci. Model Dev., 8, 2967-2975, doi:10.5194/gmd-8-2967-2015, 2015
Evaluation of modeled surface ozone biases as a function of cloud cover fraction
Summary: This study focuses on the evaluation of regional air quality model's performance based on the cloud information from satellites. While cloud information is crucial in photochemistry model, the definitions of cloud fraction from model and satellite are not physically consistent. We demonstrate that improper modeling of cloud fraction is correlated with surface ozone bias, and we also show that current model cloud field might be too bright, causing an overestimation of surface ozone level.
Geosci. Model Dev., 8, 2959-2965, doi:10.5194/gmd-8-2959-2015, 2015
MOPS-1.0: towards a model for the regulation of the global oceanic nitrogen budget by marine biogeochemical processes
Summary: We use a global model of oceanic P, N, and O2 cycles to investigate consequences of uncertainties in description of organic matter sinking, remineralization, denitrification, and N2-Fixation. After all biogeochemical and physical processes have been spun-up into a dynamically consistent steady-state, particle sinking and oxidant affinities of aerobic and anaerobic remineralization determine the extent of oxygen minimum zones, global nitrogen fluxes, and the oceanic nitrogen inventory.
Geosci. Model Dev., 8, 2929-2957, doi:10.5194/gmd-8-2929-2015, 2015
Improved simulation of precipitation in the tropics using a modified BMJ scheme in the WRF model
Summary: In this study the BMJ scheme, a convective adjustment scheme where temperature and humidity are relaxed towards reference profiles, as implemented in the WRF model version 3.3.1, is modified so that the precipitation produced by the model is in better agreement with that observed as given by the Tropical Rainfall Measuring Mission (TRMM) 3B42 data set. The "modified BMJ" scheme gives a better representation of the observed rainfall for the whole tropics in both winter and summer seasons.
Geosci. Model Dev., 8, 2915-2928, doi:10.5194/gmd-8-2915-2015, 2015