Assertion: aerosol's impact | /r/HasProperty | studied via observation
Facets:
Source sentences:
text: Mimics a natural process :  Stratospheric sulfur aerosols are created by existing natural processes (especially volcanoes), whose impacts have been studied via observations.  
text: : Stratospheric sulfur aerosols are created by existing natural processes (especially volcanoes), whose impacts have been studied via observations.