Purdue University



This is a nice unbiased study that I find intriguing and has merit. I think it would be interesting to have some talk about the instrument accuracy and type ?for the various mentioned wind speed measurements. This may have also been done, but I would also like to see the measurement times for each of the instruments to ensure they are recording for the same time. Also, understanding measurement heights is essential. Not all of these instruments are measuring at the same height.Local effects can plague several of these instruments, especially if instrument placement is not sited correctly (which is very common with Weather Underground, Accuweather, and WeatherBug. These instruments are also not calibrated/maintained regularly and can potentially yield troubling reports.As far as inversions, they can set up on very small scales (two locations within a mile of each other may not yield same observations). There are inversion measurement sticks where you can measure the temperature at two different heights and determine if an inversion is present. I’m not sure how these apps are determining inversion presence/forecasts (and we will probably never be allowed to see what’s inside the black box). This presentation does a good job of conveying the uncertainty and the inconsistency between the tools. None of them truly replace measuring the wind speed and inversion presence while in the field. Which one should we trust? Well… I’d say that the Purdue Spray App would probably be the least likely to correctly predict ( I did enjoy Joe’s humor though). I am finding it interesting that all of the apps have a False Positive of 11%. Were these all the same days? I think it would be interesting to dig deeper into this to find common times that the models are forecasting false positives. It would also be nice to do a study to determine general setup times for temperature inversions. Some setup fairly early.I don’t have a comment/enough experience with inversions to provide comment on effect of spraying during particular inversions. I’m also not sure any studies looking into this. Maybe look into studies in Missouri?Austin PearsonPurdue Tipton County, ANR educator1-8-2019 ................
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