Inhibition of Snowfall by Pollution Aerosols
Inhibition of Snowfall by Pollutant Aerosols (ISPA) studies the link between pollution aerosols and snowfall rates in the Mount Werner area near Steamboat Springs, Colorado from January 14 - February 28, 2010.
ISPA studied the link between pollution aerosols and snowfall rates in the Mount Werner area near Steamboat Springs, Colorado from January 14 - February 28, 2010. The study will help to determine the connection with pollution and snowfall amounts, as some pollutants decrease snowfall levels. The project is being carried out for the Desert Research Institute's Storm Peak Laboratory (SPL) on Mount Werner.
Pollution causes decreased droplet size which in turn decreases the riming collection effeficiency on snowflakes, resulting in decreased snowfall during the season. This has direct effects on hydrology, snow pack levels and the ski industry.
EOL provided the ISS-MAPR facility to obtain temperature and humidity profiles with altitude, cloud top height and temperature, depths of the snow layer, crystal fall speed and riming extent.
Along with the two ground-based systems, the University of Wyoming King Air will be deployed 6 times during ISPA to fly over Mount Werner, down to southwestern Colorado and back, to sample a high-altitude horizontal profile of the atmosphere. Additionally, SPL will launch weather balloons twice daily throughout the six week study.
- The ISPA effect of enhanced cloud condensation nuclei (CCN) suppresses snow water equivalent (SWE) on the upwind slope and enhances SWE on the leeward slop.
- This magnitude of the ISPA effect is directly dependent on the orographic cloud liquid water content (LWC), cloud depth, and cloud lifetime.
- The ISPA effect increases from low to moderate CCN levels (e.g., 100-500 cm-3), but levels off as CCN concentration increases further.
- The ISPA effect varies geographically: it is enhanced in the San Juan Mountains which are subject to higher LWC and greater variation in CCN concentration than in the northern Colorado mountain ranges.
- The Weather Research and Forecasting-Chemistry model can be used to accurately initialize CCN concentrations in the Regional Atmospheric Modeling System cloud-resolving model.