Assessing atmospheric dust modelling performance of WRF-Chem over the semi-arid and arid regions around the Mediterranean

Abstract

Abstract. In this study we aim at optimizing the WRF-Chem model performance for the purpose of operational forecasting of dust transport over the eastern Mediterranean. For this reason, we compare the model output to observations in order to assess its capacity to realistically reproduce the aerosol optical depth (AOD), focusing on three key regions: North Africa, the Arabian Peninsula and the eastern Mediterranean. Three sets of four simulations each have been performed for the sixmonth period of spring and summer 2011. Each simulation set uses a different dust emission parametrisation and for each parametrisation, the dust emissions are multiplied with various coefficients in order to tune the model performance. Our approach is based on the model assessment across spatial and temporal scales by comparing its outputs to AOD observations from satellites and ground-based stations, as well as airborne measurements of aerosol extinction coefficients over the Sahara.Tuning the model performance by applying a coefficient to dust emissions may reduce the model AOD bias over a region, but may increase it in other regions. Concerning dust transport over the eastern Mediterranean, the model was shown to realistically reproduce the major transport events, however failing to capture the regional background AOD. Model assessment over the entire domain and simulation period shows that the model presents temporal and spatial variability similar to observed AODs, regardless of the applied dust emission parametrisation. However, when focusing on specific regions, the model's skill may vary significantly. Further comparison of the model simulations to airborne measurements of the vertical profiles of extinction coefficients over North Africa suggests that the model may realistically reproduce the total atmospheric column AOD. Finally, we show that the inclusion of a finer dust mode (less than 1 μm) in the model presents the advantage of relaxing unrealistically large atmospheric dust loads and yet reproducing realistic AOD values.

Analysis of a severe dust storm and its impact on air quality conditions using WRF-Chem modeling, satellite imagery, and ground observations

“…Data is referred to hourly AQIs calculated in the UAE over the selected period Fig. 10 Breakdown of the Air Quality Indexes (AQIs) calculated in the UAE during the days of the dust event from 29 March to 4 April 2015 concentration might be supported by the fact that PM 10 was mostly generated by natural contributions rather than anthropogenic contributions (Flaounas et al 2016).…”

Simulating the meteorology and PM10 concentrations in Arizona dust storms using the Weather Research and Forecasting model with Chemistry (Wrf-Chem)

“…Arid and semi-arid climates produce occasional meteorological regimes of turbulent, gusty winds and blowing dust, wherever the landscapes might be: North Africa (e.g., Flaounas et al 2016), China and Mongolia (e.g., Su and Fung 2015), or the southwestern United States (e.g., Vukovic et al 2014). The predominant global source of mineral dust aerosols, these storms wreak havoc at local and regional scales and alter the global atmospheric energy and heating balances (e.g., Kumar et al 2014;Zhao et al 2011;.…”

The AFWA dust emission scheme for the GOCART aerosol model in WRF-Chem v3.8.1

“…As a result, an alternative dust emission scheme option was developed to augment the WRF-Chem GOCART code. Several journal articles briefly discuss the use of the AER and AFWA modifications (e.g., Su and Fung, 2015;Wang et al, 2015;Teixeira et al, 2016;Rizza et al, 2016;Fountoukis et al, 2016;Flaounas et al, 2016;Uzan et al, 2016;Nabavi, 2017;Cremades et al, 2017), but full documentation of the AFWA scheme has not yet been published. The purpose of this publication is therefore to document for the broader modeling community the alternate dust emission scheme (hereafter referred to as the AFWA scheme), its intended use, and how it compares with the other available dust emission schemes included in WRF-Chem GOCART.…”