Clouds and ozone
It's been a week since the field site had fresh snowfall, but the clouds have not gone away. Ozone has also stayed relatively low. Clouds do two things to mitigate ozone formation. 1) They lower the intensity of sunlight reaching the surface, which is an important ingredient in ozone formation. 2) They can prevent the formation of a stable boundary layer, which tends to trap pollutants close to the surface. So far, fresh snow has not coincided with sunlight, which may be why ozone is relatively low compared to last year, when there was lots of fresh snow AND sunlight.
The good news is that we have had snow throughout the campaign, so will still get the data we need to calculate NOx recycling rates by the snow. This information will be used in models to determine the efficacy of VOC versus NOx emission reductions for ozone in wintertime.
There is one week left in this year's field campaign. I will update you on the status next week! Below, is a beautiful picture of snow crystals that Maria took in the field yesterday.