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Indonesian volcano may cut President's visit short

By: Dr. Jeff Masters, 3:01 PM GMT on November 09, 2010

President Obama is in Jakarta, Indonesia, but that nation's most active volcano--Mount Merapi on Java--is spewing enough ash to potentially cut the President's visit short. Merapi (literally "Mountain of Fire" in Javanese) has been erupting since late October, and the mountain's pyroclastic flows and ash have been blamed for the deaths of over 150 Indonesians since the eruption began. The capital city of Jakarta lies about 250 miles west-northwest of Merapi, and received ash from the volcano over the weekend. At Jakarta's Soekarno-Hatta Airport, airlines canceled 36 flights on Saturday, and an additional 50 flights on Sunday. The airport handles about 900 flights per day. The Indonesian Disaster Management Office reported that volcanic ash from Merapi fell in Jakarta and some nearby areas such as Bogor and Puncak on Saturday night, but only in very light falls. No flights were canceled yesterday, as the ash cloud remained about 50 miles to the south of the city.

Figure 1. Signs of the eruption at Mount Merapi managed to puncture the persistent cloud cover over Java on November 5, 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this natural-color image the same day. The volcano's plume formed a V shape, fanning out to the west from the summit and casting shadows on the surrounding clouds below. According to the Volcanic Ash Advisory Center in Darwin, Australia, the ash plume rose to at least 55,000 feet (16 kilometers) in altitude and stretched 220 miles (350 km) to the west and southwest, as of 12:13 a.m. local time on November 6 (17:13 UTC, Nov 5). Image credit: NASA.

The winds today are blowing from east to west over the Merapi volcano, and are expected to continue this direction for the remainder of the day. According to the latest Volcanic ash advisory from the Darwin, Australia Volcanic Ash Advisory Center (Figure 2), the ash from Merapi extends about 140 miles to the west of the volcano, and is expected to remain just south of Jakarta today. However, the ash cloud is sufficiently close to the city that just a small change in wind direction could bring ash to Jakarta, which might shut down the airport. A run I performed using NOAA's HYSPLIT trajectory model (Figure 2, right side) shows the potential for ash to reach Jakarta if Merapi erupts continuously for 48 hours, beginning at 1am EST this morning. So, the President will have to keep a careful eye on Merapi today in case the ash cloud approaches Jakarta.

Figure 2. Latest volcanic ash advisory from the Darwin, Australia Volcanic Ash Advisory Center (left) predicts that ash from Merapi will stay just south of Jakarta today. NOAA's HYSPLIT trajectory model was run assuming a continuous 48-hour eruption of the volcano began at 1am EST this morning. That model predicts that the ash could from Merapi could come very close to Jakarta by 1am EST on Thursday.

Impact of Merapi on the climate
The amount of sulfur dioxide and ash that Merapi has thrown into the atmosphere thus far has been relatively minor as volcanic eruptions go, and I don't expect Merapi's eruption will cause a noticeable influence on the climate. As I discuss on our Volcanoes and climate web page, major volcanic eruptions in the tropics have, in the past, caused substantial cooling of Earth's climate by injecting large amounts of sulfur dioxide into the stratosphere. The most notable such eruption in recent history was in 1815 by the Indonesian volcano Tambora. The sulfur pumped by this eruption into the stratosphere dimmed sunlight so extensively that global temperatures fell by about 2°F (1°C) for 1 - 2 years afterward. This triggered the famed Year Without a Summer in 1816. Killing frosts and snow storms in May and June 1816 in Eastern Canada and New England caused widespread crop failures, and lake and river ice were observed as far south as Pennsylvania in July and August. Birger Lühr, a volcano researcher at the GFZ in Potsdam, Germany, commented in Der Spiegel magazine that Merapi has a magma reservoir triple the size of Tambora's. Lühr did not expect that the current eruption of Merapi would cause a massive climate-cooling event, but he did caution that the current cone of the volcano lies on top of the ruins of a more ancient crater, evidence that Merapi has had a cataclysmic eruption in the past.

Invest 93L in the Caribbean not currently a threat
An area of disturbed weather (Invest 93L) has developed in the central Caribbean, a few hundred miles south of the Dominican Republic and Puerto Rico. The heavy thunderstorm activity associated with 93L is rather limited, due in part to some dry air to the north. Wind shear is a low 5 - 10 knots and SSTs are very warm, 29°C, so we will have to watch this area for signs of development. None of the reliable global forecast models for predicting tropical cyclone formation (GFS, NOGAPS, ECMWF, and UKMET) are developing 93L into a tropical depression over the coming week, and NHC is giving 93L a 10% chance of developing into a tropical depression by Thursday.

Figure 3. Morning satellite image of Invest 93L.

I'll have a new post Wednesday morning.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.