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Systematic satellite observations of the impact of aerosols from passive volcanic degassing on local cloud properties
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Sayer, Andrew M. Grainger, R. G. Ebmeier, S. K. Carboni, E. Mather, T. A. |
| Copyright Year | 2014 |
| Description | The impact of volcanic emissions, especially from passive degassing and minor explosions, is a source of uncertainty in estimations of aerosol indirect effects. Observations of the impact of volcanic aerosol on clouds contribute to our understanding of both present-day atmospheric properties and of the pre-industrial baseline necessary to assess aerosol radiative forcing. We present systematic measurements over several years at multiple active and inactive volcanic islands in regions of low present-day aerosol burden. The timeaveraged indirect aerosol effects within 200 kilometers downwind of island volcanoes are observed using Moderate Resolution Imaging Spectroradiometer (MODIS, 2002-2013) and Advanced Along-Track Scanning Radiometer (AATSR, 2002- 2008) data. Retrievals of aerosol and cloud properties at Kılauea (Hawaii), Yasur (Vanuatu) and Piton de la Fournaise (la Reunion) are rotated about the volcanic vent to be parallel to wind direction, so that upwind and downwind retrievals can be compared. The emissions from all three volcanoes - including those from passive degassing, Strombolian activity and minor explosions - lead to measurably increased aerosol optical depth downwind of the active vent. Average cloud droplet effective radius is lower downwind of the volcano in all cases, with the peak difference ranging from 2 - 8 micrometers at the different volcanoes in different seasons. Estimations of the difference in Top of Atmosphere upward Short Wave flux upwind and downwind of the active volcanoes from NASA's Clouds and the Earth's Radiant Energy System (CERES) suggest a downwind elevation of between 10 and 45 Watts per square meter at distances of 150 - 400 kilometers from the volcano, with much greater local (less than 80 kilometers) effects. Comparison of these observations with cloud properties at isolated islands without degassing or erupting volcanoes suggests that these patterns are not purely orographic in origin. Our observations of unpolluted, isolated marine settings may capture processes similar to those in the pre-industrial marine atmosphere. |
| File Size | 1287962 |
| Page Count | 18 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150000356 |
| Archival Resource Key | ark:/13960/t0tr0x20w |
| Language | English |
| Publisher Date | 2014-10-09 |
| Access Restriction | Open |
| Subject Keyword | Aerosols Cloud Properties Satellite Observations Atmospheric Effects Earth Observing System Eos Indian Ocean Hawaii Satellite Observation Cap Clouds Pacific Islands Microwave Radiometers Degassing Albedo Cloud Physics Vents Clouds Meteorology Modis Radiometry Volcanoes Optical Thickness Volcanic Eruptions Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
