Follow On Comment To The Post – New Paper “Why Do Tornados And Hail Storms Rest On Weekends” By Rosenfeld and Bell 2011

I received an e-mail comment on the post

New Paper “Why Do Tornados And Hail Storms Rest On Weekends” By Rosenfeld and Bell 2011

The very informative comment is

Not all aerosols peak during the week. It appears that elemental (also called black) carbon, mainly from diesels, is at its lowest concentrations on Sunday and Monday in rural middle America. Natural dusts are also lower on Sundays and Mondays – perhaps also due to less driving generally, less stirring up of road dust?  Or, is it possible that farmers do less dirt-moving on the weekends, or at least on Sunday?  Is the black carbon missing on Sundays possibly due to less use of farm equipment?  Nitrates (mainly but not exclusively a vehicular emission) exhibit the same weekly cycle. Surprisingly, power plant particle emissions do not, although sulfur dioxide levels (a gas) are lower on weekends. See this link:

Here are parts of the Abstract:

“Data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) network of aerosol samplers and NOAA monitoring sites are examined for weekly cycles. At remote and rural sites, fine particle elemental carbon, crustal elements, and coarse particle mass had pronounced (up to 20%) weekly cycles with minima on Sunday or Monday. Fine particle organic carbon and mass had smaller amplitude cycles, also with Sunday or Monday minima. There was no statistically significant weekly cycle in fine particle sulfate despite a 5 to 15% weekly cycle in power plant SO2 emissions. Although results for nitrate may be more susceptible to sampling artifacts, nitrate also showed a pronounced weekly cycle with an amplitude similar to elemental carbon……These results support a large role of diesel emissions in elemental carbon aerosol over the entire United States and suggest that a large fraction of the airborne soil dust is anthropogenic. They also suggest that studies of  weekly cycles in temperature, cloudiness, precipitation, or other meteorological variables should look for causes more in light-absorbing particles and possible ice nucleation by dust rather than sulfate or total aerosol….”

Hope this is of interest,

Tom Grahame

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