Photochemical grid model implementation and application of VOC, NOx, and O3 source apportionment
Summary: The implementation and application of the Integrated Source Apportionment Method (ISAM) for O3 and its precursors for the Community Multiscale Air Quality (CMAQ) model are described. CMAQ-ISAM is a hybrid of source apportionment and source sensitivity in that O3 production is attributed to precursor sources based on the O3 formation regime. CMAQ-ISAM offers a source attribution tool for the purposes of quantifying and understanding sources and impacts of regional air pollution.
The impact of periodization methods on the kinetic energy spectra for limited-area numerical weather prediction models
Summary: The paper deals with the comparison of the common periodization methods used to obtain spectral fields of limited-area models for numerical weather prediction. The focus is on the impact the methods have on the spectra of the fields. The results show that detrending and DCT have little impact on the spectra, as does the Boyd method for extension zone. For the ALADIN and HIRLAM methods, the impact depends on the width of the extension zone - the wider the zone, the larger impact on the spectra.
A new Geoengineering Model Intercomparison Project (GeoMIP) experiment designed for climate and chemistry models
Summary: A new Geoengineering Model Intercomparison Project (GeoMIP) experiment “G4 specified stratospheric aerosols” (G4SSA) is proposed to investigate the impact of stratospheric aerosol geoengineering on atmosphere, chemistry, dynamics, climate, and the environment. In contrast to the earlier G4 GeoMIP experiment, which requires an emission of sulfur dioxide (SO2) into the model, a prescribed aerosol forcing file is provided to the community, to be consistently applied to future model experiments.
S. Tilmes, M. J. Mills, U. Niemeier, H. Schmidt, A. Robock, B. Kravitz, J.-F. Lamarque, G. Pitari, and J. M. English Geosci. Model Dev., 8, 43-49, 2015 AbstractFinal Revised Paper (PDF, 256 KB)Discussion Paper (GMDD)
15 Jan 2015
High-resolution air quality simulation over Europe with the chemistry transport model CHIMERE
Summary: The model reproduces the temporal variability of NO2, O3, PM10, PM2.5 better at rural than urban background stations.
The fractional biases show that the model performs slightly better at RB sites than at UB sites for NO2, O3 and PM10.
At UB sites, CHIMERE reproduces PM2.5 better than PM10.
This is primarily the result of an underestimation of coarse particulate matter (PM) associated with uncertainties on SOA chemistry and their precursor emissions, dust and sea salt.
Parameterizing deep convection using the assumed probability density function method
Summary: Representing clouds in climate models is a challenging problem. It is particularly difficult to represent deep convective clouds and, historically, deep convective parameterization is separate from the representation of other cloud types. Here we use a single-column cloud model to simulate three deep convective cases, and two shallow cloud cases. The results look reasonable, demonstrating that it may be possible to use one parameterization within a climate model for all cloud types.
ORACLE (v1.0): module to simulate the organic aerosol composition and evolution in the atmosphere
Summary: A computationally efficient module for the description of OA composition and evolution in the atmosphere has been developed. This module subdivides OA into several compounds based on their source of origin and volatility, allowing the quantification of POA vs. SOA as well as biogenic vs. anthropogenic contributions to OA concentrations. Such fundamental information can shed light on long-term changes in OA abundance, and hence project the effects of OA on future air quality and climate.
MeteoIO 2.4.2: a preprocessing library for meteorological data
Summary: The open-source MeteoIO library has been designed to perform the data preprocessing required by numerical models using large meteorological data sets, with a strong emphasis on simplicity and modularity. It retrieves, filters and resamples the data if necessary as well as provides spatial interpolations and parameterizations. It presents a uniform interface to meteorological data in the models, hides the complexity of the preprocessing and guarantees a robust behaviour in case of data errors.
A simplified permafrost-carbon model for long-term climate studies with the CLIMBER-2 coupled earth system model
Summary: Permafrost is ground that remains frozen for two or more consecutive years. An estimated 50% of the global below-ground organic carbon is stored in soils of the permafrost zone. This study presents the development and validation of a simplified permafrost-carbon mechanism for the CLIMBER-2 model. Our model development allows, for the first time, the study of the role of permafrost soils in the global carbon cycle for long timescales and for coupled palaeoclimate Earth system modelling studies.
DYPTOP: a cost-efficient TOPMODEL implementation to simulate sub-grid spatio-temporal dynamics of global wetlands and peatlands
Summary: Simulating the spatio-temporal dynamics of inundation is key to understanding the role of wetlands under past and future climate change. Here, we describe and assess the DYPTOP model that predicts the extent of inundation and the global spatial distribution of peatlands. DYPTOP makes use of high-resolution topography information and uses ecosystem water balance and peatland soil C balance criteria to simulate peatland spatial dynamics and carbon accumulation.
Evaluation of North Eurasian snow-off dates in the ECHAM5.4 atmospheric general circulation model
Summary: Snowmelt influences greatly the climatic conditions in spring. This study evaluates the timing of springtime end of snowmelt in the ECHAM5 model. A key finding is that, in much of northern Eurasia, snow disappears too early in ECHAM5, in spite of a slight cold bias in spring. This points to the need for a more comprehensive treatment of the surface energy budget. In particular, the surface temperature for the snow-covered and snow-free parts of a climate model grid cell should be separated.
P. Räisänen, A. Luomaranta, H. Järvinen, M. Takala, K. Jylhä, O. N. Bulygina, K. Luojus, A. Riihelä, A. Laaksonen, J. Koskinen, and J. Pulliainen Geosci. Model Dev., 7, 3037-3057, 2014 AbstractFinal Revised Paper (PDF, 1516 KB)Discussion Paper (GMDD)
18 Dec 2014
A global finite-element shallow-water model supporting continuous and discontinuous elements
Summary: This paper compares continuous and discontinuous discretizations of the shallow-water equations on the sphere using the flux reconstruction formulation. The discontinuous framework comes at a cost, including a reduced time step size and higher computational expense, but has a number of desirable properties which may make it desirable for future use in atmospheric models.
A strategy for GIS-based 3-D slope stability modelling over large areas
Summary: The article deals with strategies to (i) reduce computation time and to (ii) appropriately account for uncertain input parameters when applying an open source GIS sliding surface model to estimate landslide susceptibility for a 90km² study area in central Italy. For (i), the area is split into a large number of tiles, enabling the exploitation of multi-processor computing environments. For (ii), the model is run with various parameter combinations to compute the slope failure probability.
A Lagrangian advection scheme with shape matrix (LASM) for solving advection problems
Summary: In this paper we have developed a new Lagrangian advection scheme that describes the shape of discrete parcels by linear deformation matrix. An adaptive interparcel mixing algorithm is also devised to reduce the possible aliasing errors. Several test cases are conducted to validate the new scheme.
Predicting the response of the Amazon rainforest to persistent drought conditions under current and future climates: a major challenge for global land surface models
E. Joetzjer, C. Delire, H. Douville, P. Ciais, B. Decharme, R. Fisher, B. Christoffersen, J. C. Calvet, A. C. L. da Costa, L. V. Ferreira, and P. Meir Geosci. Model Dev., 7, 2933-2950, 2014 AbstractFinal Revised Paper (PDF, 1499 KB)Discussion Paper (GMDD)