I’m experiencing abnormal drops in concentration near the +/-50m mark along the side of the road where the direction of the wind is blowing from. When running R-LINE on cases where the wind direction is close (<5 degrees) to perpendicular relative to the road axis. For example, a wind blowing westward for a north-south road.
Below I’ve attached the concentration contour plot generated from a sample run with input of a wind direction of 90 degrees (westward) at a speed of 0.86. The road is the shaded grey rectangle in the plot. For this run, I adapted numbers from the example cases that were provided in the R-LINE v1_2 download. I’ll also include screenshots of the input meteorological data.
Met data used:
I’ve tested this in the 270 degree direction as well with similar results.
Similar met data with 270 degree as wind direction!
I’ve also conducted a test with north-south winds on a east-west road, and found similar abnormalities.
I’ve also conducted tests for perpendicular wind cases using the Idaho Falls sample data provided on the CMAS website. No alternations were done to the data except for adding more receptors to construct the contour plot. I analyzed results for the hour with meteorological conditions as follows: wind speed (8.1) wind direction (272.4). The Idaho Falls contour plot shows a depression as well, although the depression is less severe. I also conducted a run with a wind speed of 4 at 90 degrees, and it appears that a lower wind speeds make the abnormality more apparent compared to higher speeds.
Please advise on a) an explanation of why this abnormality occurs and b) solutions to this issue. It’s important for me to analyze winds at these angles as I need my results to reflect many real life possibilities.