Is Air Pollution Impacting Winter Orographic Precipitation in Utah?

Authors

  • Don A Griffith North American Weather Consultants, Inc. Sandy, Utah
  • Mark E Solak North American Weather Consultants, Inc. Sandy, Utah
  • David P Yorty North American Weather Consultants, Inc. Sandy, Utah

Abstract

Winter precipitation data from selected locations within the States of Utah and Nevada were analyzed to determine if there were any indications of reductions in mountainous precipitation when compared with upwind valley precipitation. This work followed the approached utilized in a comprehensive study of precipitation in Israel and California that indicated the orographic component of precipitation was declining at precipitation stations at mountain locations which were downwind of major cities. The authors of that study theorized that these reductions were due to the transport of air pollution from the cities into winter storms at these downwind mountainous locations leading to microphysical changes within the affected clouds resulting in reductions in observed precipitation. The work which we performed in Utah and Nevada indicated similar reductions in mountainous precipitation downwind of the Salt Lake City/Provo metropolitan complex. These indicated reductions in precipitation extended downwind of the first mountain barrier into a mountain valley location and into the upwind slope of a second mountain barrier some 80 km downwind. Reductions in precipitation at other mountain stations in Utah and Nevada were not indicated. These stations were located in more rural settings which may suggest that air pollution from major cities may in fact be related to the reductions in precipitation that are indicated downwind of the Salt Lake City/Provo metropolitan complex.

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Scientific Papers