Volcanic impact on the climate – the stratospheric aerosol load in the period 2006–2015

• Abstract. We present a study on the stratospheric aerosol load during 2006–2015, discuss the influence from volcanism and other sources, and reconstruct an AOD data-set in a resolution of 1° latitudinally and 8 days timewise. Our attempt is to include the entire stratosphere, from the tropopause to the almost particle free altitudes of the mid-stratosphere. A dynamic tropopause of 1.5 PVU was found to be the best suited one, enclosing almost all of the volcanic signals in the CALIOP data-set. New methods were developed to handle bias in the data. The data were successfully cleaned from polar stratospheric clouds using a temperature threshold of 195 K. Furthermore, a method was developed to correct data when the CALIPSO laser beam was strongly attenuated by volcanic aerosol, preventing a negative bias in the AOD data-set. Tropospheric influence, likely from upwelling dust, was found in the extratropical transition layer in spring. Eruptions of both extratropical and tropical volcanoes that injected aerosol into the stratosphere impacted the stratospheric aerosol load for up to a year if their clouds reached lower than 20 km altitudes, whereas deeper reaching tropical injections rose in the tropical pipe and impacted it for several years. Over the years 2006–2015, volcanic eruptions increased the stratospheric AOD on average by ~ 40 %. In absolute numbers the stratospheric AOD and radiative forcing amounted to 0.008 and −0.2 Wm−2, respectively.

Ämnesord

NATURVETENSKAP  -- Fysik -- Subatomär fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Subatomic Physics (hsv//eng)

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