Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Model evaluation paper
04 Oct 2017
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Geoscientific Model Development (GMD).
Air quality in the Kathmandu Valley: WRF and WRF-Chem simulations of meteorology and black carbon concentrations
Andrea Mues1, Axel Lauer2, Aurelia Lupascu1, Maheswar Rupakheti1, Friderike Kuik1, and Mark G. Lawrence1 1Institute for Advanced Sustainability Studies (IASS), Potsdam, 14467, Germany
2Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
Abstract. An evaluation of the meteorology simulated using the Weather Research and Forecast (WRF) model for the region South Asia and Nepal with a focus on the Kathmandu Valley is presented. A particular focus of the model evaluation is placed on meteorological parameters that are highly relevant to air quality such as wind speed and direction, boundary layer height and precipitation. The same model setup is then used for simulations with WRF including chemistry and aerosols (WRF-Chem). A WRF-Chem simulation has been performed using the state-of-the-art emission database EDGAR HTAP v2.2, along with a sensitivity simulation using observation-based black carbon emission fluxes for the Kathmandu Valley. The WRF-Chem simulations are analyzed in comparison to black carbon measurements in the valley and to each other.

The evaluation of the WRF simulation with a horizontal resolution of 3 × 3 km2, shows that the model is often able to capture important meteorological parameters inside the Kathmandu Valley and the results for most meteorological parameters are well within the range of biases found in other WRF studies especially in mountain areas. But the evaluation results also clearly highlight the difficulties of capturing meteorological parameters in such complex terrain and reproducing subgrid-scale processes with a horizontal resolution of 3 × 3 km2. The measured black carbon concentrations are typically systematically and strongly underestimated by WRF-Chem. A sensitivity study with improved emissions in the Kathmandu Valley shows significantly reduced biases but also underlines several limitations of such corrections. Further improvements of the model and of the emission data are needed before being able to use the model to robustly assess air pollution mitigation scenarios in the Kathmandu region.

Citation: Mues, A., Lauer, A., Lupascu, A., Rupakheti, M., Kuik, F., and Lawrence, M. G.: Air quality in the Kathmandu Valley: WRF and WRF-Chem simulations of meteorology and black carbon concentrations, Geosci. Model Dev. Discuss.,, in review, 2017.
Andrea Mues et al.
Andrea Mues et al.

Model code and software

Modifications of WRF-Chem 3.5.1 described in Mues et al., Geosci. Model Dev. A. Mues and A. Lauer
Andrea Mues et al.


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