Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The 1991 Mt. Pinatubo Eruption Provides a Natural Test for the Influence of Arctic Circulation onClimate

13.03.2003


A recent NASA-funded study has linked the 1991 eruption of the Mount Pinatubo to a strengthening of a climate pattern called the Arctic Oscillation. For two years following the volcanic eruption, the Arctic Oscillation caused winter warming over land areas in the high and middle latitudes of the Northern Hemisphere, despite a cooling effect from volcanic particles that blocked sunlight.


The Arctic Oscillation (AO)

A positive phase of the Arctic Oscillation (top) is associated with strengthening of winds circulating counterclockwise around the North Pole north of 55°N, that is, roughly in line with Moscow, Belfast, and Ketchikan, Alaska. In winter these winds pull more warm air from oceans to continents causing winter warming, and like a top spinning very fast, they hold a tight pattern over the North Pole and keep frigid air from moving south. Cool winds sweep across eastern Canada while North Atlantic storms bring rain and mild temperatures to Northern Europe. Drought conditions prevail over the Mediterranean region.

During the negative phase of the Arctic Oscillation (bottom), cool continental air plunges into the Midwestern United States and Western Europe while storms bring rainfall to the Mediterranean region. Credit: David W. J. Thompson, J. M. Wallace


Eruption of Mount Pinatubo, Philippines, July 1991

Strong explosive volcanic eruptions, like ones of the Mt. Pinatubo in Philippines in June 1991, inject millions of ton of sulfur dioxide gas at the altitudes of about 15 miles where it interacts with water vapor producing a volcanic aerosol layer that consists of tiny droplets of highly concentrated sulfuric acid.
As a result of the Pinatubo eruption, globally averaged surface temperature decreased by about 0.3 Kelvin (0.3 Celsius) for two years after the eruption and the temperature in the tropical lower stratosphere increased by about 2-3 Kelvin (2-3 Celsius). The tropospheric response over most land areas in the Northern Hemisphere is characterized by summer cooling and winter warming. Credit: U.S. Geological Survey, J.N. Marso, July 1991



One mission of NASA’s Earth Science Enterprise, which funded this research, is to better understand how the Earth system responds to human and naturally-induced changes, such as large volcanic eruptions.

“This study clarifies the effect of strong volcanic eruptions on climate, important by itself, and helps to better predict possible weather and short-term climate variations after strong volcanic eruptions,” said Georgiy Stenchikov, a researcher at Rutgers University’s Department of Environmental Sciences, New Brunswick, N.J., and lead author on a paper that appeared in a recent issue of the Journal of Geophysical Research.


A positive phase of the Arctic Oscillation has slowly strengthened over the few last decades and has been associated in prior research with observed climate warming.

“The study has important implications to climate change because it provides a test for mechanisms of the Arctic Oscillation,” Stenchikov said.

A positive phase of the Arctic Oscillation is associated with strengthening of winds circulating counterclockwise around the North Pole north of 55°N, that is, roughly in line with Moscow, Belfast, and Ketchikan, Alaska. In winter these winds pull more warm air from oceans to continents causing winter warming, and like a top spinning very fast, they hold a tight pattern over the North Pole and keep frigid air from moving south.

According to this research, temperature changes caused by a radiative effect of volcanic aerosols in two lower layers of the atmosphere, the troposphere and the stratosphere, can lead to a positive Arctic Oscillation phase. The troposphere extends from Earth’s surface to an altitude of 7 miles in the polar regions and expands to 13 miles in the tropics. The stratosphere is the next layer up with the top at an altitude of about 30 miles.

The study uses a general circulation model developed at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory to simulate how volcanic aerosols following the Pinatubo eruption impacted the climate.

In the troposphere, volcanic aerosols reflect solar radiation and cool the Earth’s surface, decreasing temperature differences between the equator and the North Pole in the bottom atmospheric layer. These changes end up inhibiting processes that slow counterclockwise winds that blow around the North Pole mostly in the stratosphere. This in turn strengthens a positive phase of the Arctic Oscillation.

In the stratosphere, volcanic aerosols absorb solar radiation, warm the lower stratosphere (about 15 miles above the Earth’s surface) and increase stratospheric temperature differences between the equator and the North Pole. These changes strengthen westerly winds in the lower stratosphere and help to create a positive phase of the Arctic Oscillation.

In previous research, an observed positive Arctic Oscillation trend has been attributed to greenhouse warming that led to an increase of stratospheric temperature differences between equator and pole. But this study finds that tropospheric temperature change in the course of climate warming may play an even greater role.

In one type of computer simulation, Stenchikov and colleagues isolated the contribution of a decreased temperature difference in the troposphere, and found that it could produce a positive phase of the Arctic Oscillation by itself. That’s because greenhouse heating near the North Pole melts reflective sea ice and snow, and reveals more water and land surfaces. These surfaces absorb the Sun’s rays and increasingly warm the Earth’s polar regions. Polar heating at the Earth’s surface lessens the temperature differences between the equator and North Pole in the troposphere, which ultimately strengthens a positive phase of the Arctic Oscillation.

The study also finds that when aerosols get into the stratosphere, very rapid reactions that destroy ozone (especially in high latitudes) take place on the surfaces of aerosol particles. When ozone gets depleted, less UV radiation is absorbed in the stratosphere. This cools the polar stratosphere, and increases the stratospheric equator-to-pole temperature difference, creating a positive phase of the Arctic Oscillation. Ozone data were obtained from NASA’s Total Ozone Mapping Spectrometer (TOMS) satellite and ozonesonde observations.

Krishna Ramanujan | NASA/Goddard Space Flight Center
Further information:
http://www.gsfc.nasa.gov/topstory/2003/0306aopin.html

More articles from Earth Sciences:

nachricht New studies increase confidence in NASA's measure of Earth's temperature
24.05.2019 | NASA/Goddard Space Flight Center

nachricht New Measurement Device: Carbon Dioxide As Geothermometer
21.05.2019 | Universität Heidelberg

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New studies increase confidence in NASA's measure of Earth's temperature

A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.

The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...

Im Focus: The geometry of an electron determined for the first time

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

On Mars, sands shift to a different drum

24.05.2019 | Physics and Astronomy

Piedmont Atlanta first in Georgia to offer new minimally invasive treatment for emphysema

24.05.2019 | Medical Engineering

Chemical juggling with three particles

24.05.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>