Location: New York
Author: Michael Schlacter
Date: Tuesday, March 24, 2009
For a few months now we have been monitoring Mount Redoubt in Alaska. This volcano has finally erupted, with volcanic ash raining down in mostly sparsely populated areas of Alaska. Preliminary reports indicate that Volcanic Ash clouds have been released into the upper Troposphere [~50,000 feet ~ 15km] and partially the lower Stratosphere for these Polar latitudes.
Besides needing to send copious amounts of volcanic ash into the stratosphere to affect worldwide weather, its latitude [60.5°N] is way too far to the North (see below) to have a significant impact on the global climate. There may be more localized effects over Northern North America and the polar regions over the next several months, but until the precise amount of ejecta is known, specific impacts are mere speculation at this juncture.
Another volcano, an undersea volcano near Tongatapu (Kingdom of Tonga) in the South Pacific Ocean, has been erupting. Its explosive eruptions have created a new volcanic island. While it is located at a more optimal latitude [21°S] (see below), its underwater source should prevent too much volcanic ash from getting too far up into the atmosphere.
Our preliminary research indicates that some ash plumes may have reached the Stratosphere, but the amount of volcanic ash does not appear at this point to be dense enough to cause global impacts. We will continue to monitor the physics & chemistry of this situation - which would have an approximate 12-month lag-time before Northern Hemispheric impacts, if any, are realized.
1.) In order for Volcanoes to have weather/climate impacts beyond its region of the World, the erupted particles need to be forcefully ejected through the Tropopause and into the Stratosphere (> 12km/9 mi. for mid-Latitudes and > 16 km/11 mi. closer to the Equator), where they can diffuse and eventually have a global reach.
2.) Separately, keep in mind that any Volcanoes located Poleward of 30° have only small impacts on Hemispheric climate. Unlike Pinatubo and Tungurahua (both located in the Tropics), Volcanoes closer to the Poles will have their contents advected toward the Northeast/Poles.
3.) Regionally, larger soot and erupted particles (> 2.2 µm) are more effective at keeping in Infrared radiation and can impart some warming effects. Smaller particles (usually containing lots of sulfur) are less effective in the IR spectrum, but stay aloft longer and increase Albedo and hence lead to cooling. (FYI, Volcanic Ash is not actually ash, but tiny jagged particles of rock and natural glass). After the infamous 1980 Mount Saint Helens eruption it took several weeks to cart away all the Ash & Soot, and until that is done in any future events, could be blown around obscuring visibility in much the same way a Forest Fire would.
4.) At the lower levels of the Troposphere, Soot & Ash (if fine enough) could also act as condensation nuclei and perhaps help "feed" regional storm systems during an upcoming Season. Ionization of the atmosphere is a tertiary impact of this particulate matter that could translate into increased lightning events also during the upcoming Season. Such particles were detected as far away as New England following the 1980 Mount St. Helens eruption.
Re-Included from last week's Discussions, for pertinence:
* Mesoscale dynamics will be primed for severe weather/tornado outbreaks early next week (possibly Sunday PM), across the South-Central U.S. Closer to the Southwest U.S. (on the rear flanks of the Dry Line from Western Kansas to southern Arizona ), this instability will spur Brush/Wild fire outbreaks.
* Regardless of rumors of a fading La Niña (it was barely an event in the 11th hour of Winter anyway) or MJO, don't overlook the fact that the East Coast [such as Boston, New York City, Washington D.C.] has had - and will end up with - a colder than normal March 2009.
* This was the 3rd consecutive March in which the Eastern U.S. experienced a top-35 NESIS-ranked Snowstorm, and March 2009 still has a ways to go. As the "surprise" snow showers this morning across NYC demonstrate: Teleconnections continue to support episodes Wintery weather through Easter, whether computer models say so or not.
* Pacific Storms will impact the Western U.S. from southwestern British Columbia down to the mountains of central California. The subsequent significance for Spring Stream-flow remains: Below the robust flow of 2008, but Above prevailing expectations of only 50-80% of normal.
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