Midlatitude Volcanoes

Volcanic eruptions of great magnitude using the term Volcanic Explosivity Index, VEI >= 3, are capable of sending plumes of ash, steam and aerosols into the Stratosphere. Along the Ring of Fire, a subduction zone encompassing Alaska, Aleutian Islands, Kamchatka and the Kurile Islands are hundreds of active volcanoes. A few of these and volcanoes in Iceland erupt with Plinian force every year. Because these eruptions occur close to the Arctic Circle, they are capable of disturbing the Polar Vortex and changing regional climate. Sulfur dioxide emissions within the plume are converted to sulfate as can be noted on the chart. Aerosol Optical Depth (AOD) is a measure of sulfate interference with visible, infrared and ultraviolet wavelengths and is interpreted as mass. However satellites capture only a glimpse of the total mass emissions. There is also much cloud cover and less satellite coverage at high latitudes. Arctic Oscillation (AO)is an interpretation of sea level pressure between the top of Greenland and further south near Iceland. Usually after a major eruption of a midlatitude (30-60N+) volcano, if the plume is blown toward the pole and occurs just before or during Arctic winter, sulfate will enter the lower stratosphere of the Arctic region. This will result in the formation of Polar Stratospheric Clouds (PSCs). Within the PSCs ice forms from water vapor and nitrates on which CFCs accumulate. It is here wherein Ozone is depleted in reactions with free chlorine ions liberated by reactions with nitrates and hydroxyl ions. Another disturbance may occur if the ash plume is very large with a tremendous mass of hot water vapor, ash and aerosols. The heat of the ash plume is sufficient to displace or split the vortex as it has a greater potential vorticity. Just how this occurs depends on the strength and direction of upper stratospheric winds called Quasibiennial Oscillations. A displacement or split of the Polar Vortex is called a Stratospheric Warming. A major warming is a split of the vortex and the cold air within the vortex will descend south into the continents of Asia, Europe and North America. This is the first chart that illustrates how these volcanoes near the Arctic Circle sustain PSClouds, deplete Ozone and cause Stratospheric Warmings. It is well known  that Planetary waves generally cause SWs to occur. The transport of ozone between the tropics and the arctic is through the Brewer Dobson circulation. Planetary waves carry hot moist air with trace gases from the tropics to midlatitudes . If a Rossby wave has enough momentum to reach high latitudes it could slow down the polar night jet and displace or split the vortex, A volcanic plume reaching the stratosphere could push a planetary upward in latitude and altitude and thereby cause a stratospheric warming. Water has a very high heat capacity. Volcanic plumes from Plinian eruptions are composed mostly of ash, steam (water vapor) and carbon dioxide. If such an event occurs in late fall or during Arctic winter, these hot plumes of steam and ash breaking through the tropopause will change the course of the Rossby wave pushing in upward into the Polar vortex.  A tremendous eruption of ash, steam and aerosols has more than sufficient energy in the form of heat and chemical bonds, condensation nuclei to not only disturb the Polar Vortex but to be the primary source of its formation. This is my theory and the purpose of arcticvolcanoes. Energy is need for transport of aerosols and reactions to occur and these volcanic eruptions provide it.


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