The operational configuration of the CALIOPE-AQFS is described in Arévalo et al., 2014.
Whereas the operational outputs from the CALIOPE-AQFS were used for the analysis performed in Chapter 4, two specific simulations were run for the pollution dynamics characterisations of Chapters 5 and 6. For the latter, this section presents the setup of the CALIOPE-AQFS system that was used.
The meteorological model, WRF-ARW, version 3.5.1 runs over EU12 using initial and boundary conditions from the Global Forecast System (GFS/FNL) dataset that has 6-h
temporal resolution and 0.5º x 0.5º horizontal resolution (http://rda.ucar.edu/datasets/ds083.2/). In order to heat the model, a 12-hour spin-up is used prior the 24-h run of each simulated day. Vertically, WRF-ARW is configured with 38 σ vertical levels from the surface up to 50 hPa, with 11 levels characterizing the planetary boundary layer (PBL). The configuration and setup of CALIOPE-AQFS for Chapters 5 and 6 is shown in Table 3-1.
Chemical Transport Model CMAQv5.0.1 (Chapter 5) / CMAQv5.0.2 (Chapter 6) Chemical mechanism cb05cl_ae5_aq (Chapter5) / cb05-TUCL-aero6
(Chapter 6)
Chemical boundary conditions MOZART4-GEOS5 forecast (1.7º x 2.5º, 6h) CTM spin-up period 3 days (Chapter 5) / 7 days (Chapter 6) ISAM tracked species O3, NOx, NMVOC (Chapter 6) Mother domain 12 km x 12 km resolution
over Europe (nx, ny, nz) 478 x 398 x 15 Nested domain 4 km x 4 km over the
Iberian Peninsula (nx, ny, nz) 397 x 397 x 15
CMAQ parametrizations Horizontal/Vertical advection scheme: Horiz.:
Yamartino mass-conserving/ Vert.: Piecewise Parabolic Method (PPM)
Vertical diffusion module: Asymmetric Convective Model v2 (ACM2) Eddy diffusivity approach
Dry deposition routine: Models-3 + Cl species
The Meteorology-Chemistry Interface Processor of CMAQ (MCIPv4.1) is used to collapse the 38 σ levels of WRF into 15 vertical layers, 12 of which are below 1500 meters above ground level (magl). The chosen diffusion and advection schemes are shown in Table 3-1.
It has been proven that using daily time and space varying chemical boundary conditions improves air quality model skills over Europe respect seasonal or invariant boundary conditions (Szopa et al., 2009; Akritidis et al., 2013). This is why the CALIOPE-AQFS uses the outputs of a global chemistry model as boundary conditions for the CMAQ model.
However, the choice of chemical boundary conditions is an important factor of variability of the performance of an area-limited air quality modelling system (Marécal et al., 2015).
For example, a recent study by Terrenoire et al. (2015) over Europe using the CHIMERE CTM shows that there is an overestimation of O3 concentrations related to an underestimation of NO2 and an overestimation of O3 concentrations of the chemical boundary conditions (from the global model Laboratoire de Météorologie Dynamique- INteraction avec la Chimie et les Aérosols – LMDz-INCA–; Hauglustaine et al., 2014). Pay et al. (2015) recently analysed the performance of two state-of-the-art 3-D global CTMs – the Model for OZone And Related chemical Tracers, Version 4 (MOZART4, Emmons et al., 2010) and the Monitoring Atmospheric Composition and Climate model (MACC, Inness et al., 2013) – in the simulation of O3 vertical profiles in several sites in Europe. To that end, they evaluated the 15-day averaged O3 concentration from ozone-sondes against the model outputs. Their results proved that MACC performs better than MOZART-4 for O3 vertical profiles. The same conclusion was obtained when using MOZART-4 and MACC as boundary conditions of the EU12 domain within the CALIOPE-AQFS and evaluating the O3 surface concentration against AirBase monitoring stations in the same 15-day period as in Pay et al. (2015) (Table 3-2).
Table 3-2. CALIOPE-AQFS performance in EU12 domain for surface O3 concentration in Europe using two different chemical boundary conditions: MACC and MOZART-4.
Average of 198 rural background stations from AirBase on the 21-31 July 2012 period Mean Bias
For the CALIOPE-AQFS simulations performed in this Ph.D. Thesis, the lack of MACC data for all the periods of study lied to the use of MOZART-4 as chemical boundary conditions for CMAQ in the EU12 domain. This model, developed by the US National Center for Atmospheric Research (NCAR) (https://www2.acom.ucar.edu/gcm/mozart) is an offline global chemical transport model particularly suited for studies of the troposphere. A comprehensive description of the model and its chemical mechanism, and a
thorough evaluation over the 2000–2007 period can be found in Emmons et al. (2010).
MOZART-4 is driven by the Atmospheric Global Climate Model Goddard Earth Observing System Model, Version 5 (GEOS-5). GEOS-5 is developed by –US National Aeronautics and Space Administration (NASA) to support its research in the fields of climate and weather prediction (http://geos5.org/wiki/index.php?title=GEOS-5_Earth_System_Modeling_and_Data_Assimilation).
The MOZART-4/GEOS-5 outputs contain 80 variables including the concentration of the main atmospheric gases and aerosols and they can be downloaded in netCDF format from a web repository (http://www.acd.ucar.edu/gctm/mozart/subset.shtml). The temporal resolution is 6 hours. The horizontal resolution is Latitude 1.9º x Longitude 2.5º. Vertically, the model is configured with 56 hybrid sigma pressure levels. The anthropogenic emissions are provided by the Argonne National Laboratory (University of Chicago) emission inventory developed for the Arctic Research of the Composition of the Troposphere (ARCTAS) project (http://bio.cgrer.uiowa.edu/arctas/emission.html) whereas the fire emissions come from the Finish Fire INventory from NCAR, Version 1.0 (FINN-v1) model that proved 1 km resolution, global estimates of the trace gas and particle emissions from open burning of biomass.
A time-independent vertical concentration profile was used to settle the initial chemical conditions and a 3-day and 7-day spin-up was used to heat the model, respectively for experiments in Chapters 5 and 6.
Regarding the CTM, two different versions have been used in this Ph.D. Thesis, version 5.0.1 (Chapter 5) and version 5.0.2 (Chapter 6). Both versions contain the updated carbon bond gas-phase mechanism (CB05) with new toluene chemistry (Whitten et al., 2010). The last release of CMAQ (Version 5.0.2) has an update on the aerosol module (AERO6 with ISORROPIA v2.1 inorganic chemistry) that is needed to perform source apportionment studies and that is the reason why the 5.0.2 version had to be used. The CB05 chemical mechanism is chosen because it performs better than other gas-phase mechanisms (SAPRC-99, CB4) implemented in CMAQ (Luecken et al. 2008; Pay et al., 2012c).