Sensitivity of mesoscale dust simulation to WRF_Chem boundary layer scheme (Case study: March 14th 2012)

Recently, local dust events increased in Khuzestan province. Therefore, knowledge on its properties can have a crucial role in future prediction and planning.

This study investigated the effect of different boundary layer schemes for dust simulation by WRF_Chem model on March 14th 2012 in Khuzestan province. To validate the model, observation data such as horizontal visibility, 10-m wind speed and PM10 were provided.

The results indicated that the MYN scheme has the highest correlation between model outputs and observation for 10-m wind speed, PM10 and horizontal visibility. Due to the highest correlation of the 10 m wind speed, horizontal visibility, PM10 respectively with 0.83, -0.76 and 0.76 values and the highest consistency with the day-night variation of PM10, MYN scheme can be selected as the most suitable scheme. At the second level, UW scheme seems to be an appropriate option. In MYN and UW schemes, the maximum wind speed in 925 hPa level was estimated 24 m/s at 03 UTC, March 14th which caused an increase in the 10 m wind speed at 06 and 09UTC. Therefore, the dust emitted from the surface to the air. Although the results of MYJ scheme showed proper correlation and temporal variation with observed, but as it determined PM10 concentration with high difference, it can’t be considered as a suitable scheme for simulation dust concentration.

Although the PM10 concentration obtained by WRF_Chem showed difference with the observation for all the selected boundary layer schemes, MYN scheme gives the most appropriate result.