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Merapi Volcanic Cloud

Due to multiple volcanic eruptions in 2008-10, stratospheric sulfate aerosol concentrations are elevated compared to recent years, with possible impacts on atmospheric chemistry and radiation. Gaseous and aerosol clouds from major explosive eruption of Indonesia's Merapi volcano on November 4-5, 2010 were measured by multiple A-train sensors.

If a volcano injects a sufficient quantity of sulfur dioxide into the stratosphere, the resulting chemical reactions can create reflective and chemically reactive aerosols that linger for months or even years, cooling climate by reflecting sunlight. At just 7.5 degrees south of the equator, Mount Merapi is positioned to have such an impact. But in November 2010, Merapi had cumulatively emitted just 1 percent of what was released by Mount Pinatubo in 1991.

Aura OMI Merapi volcanic cloud
Cumulative burdens of volcanic sulfur dioxide gas emitted by explosive eruption of Indonesia's Merapi volcano on November 4-8, 2010, as observed by the Aura Ozone Monitoring Instrument (OMI). Sulfur dioxide is measured here in Dobson Units: The greatest concentrations appear in red; the lowest in lavender. Typically used to measure ozone, the Dobson Unit is the number of molecules of gas that would be required to create a layer 0.01 millimeters thick at a temperature of 0 degrees Celsius and a pressure of 1 atmosphere (the air pressure at the surface of the Earth). 

Aura MLS Merapi volcanic cloud
Data from the Aura Microwave Limb Sounder (MLS) instrument shows significant HCl content - consistent with expected Merapi volcanic gas composition.
CALIPSO observation of the Merapi volcanic cloud
NASA's CALIPSO satellite carries a pulsating laser (lidar) that sends short pulses of light through the atmosphere. Some of the light bounces off clouds and particles in the atmosphere and returns to the satellite. The strength of the returning signal (attenuated backscatter shown in the color bar on the right) provides information about the characteristics of the clouds or aerosols (particles).

 Aura's Ozone Monitoring Instrument (OMI) monitors volcanic and anthropogenic Sulfur dioxide (SO2) from space to detect trends in volcanic and anthropogenic aerosol precursors and will provide overlap with ESA Sentinel-5 precursor mission (TropOMI) planned to launch in 2014. NASA/NOAA Ozone Monitoring and Profiling Suite (OMPS) will continue the total ozone and SO2 observational record. Decadal Survey recommended the Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission is planned to launch after 2020. It will allow more frequent monitoring of volcanic and anthropogenic SO2 pollution over North and South America.

This work shows the importance of solar-related processes in the observed variation of the atmosphere. It will be important to carry out further measurements of hydrogen oxide radicals (HOx ) and  nitrogen oxides  (NOx) constituents in order to understand the variations in ozone. Thus, measurements of the proposed Decadal Survey's Global Atmospheric Composition Mission (GACM) are necessary to continue the work on the influence of solar protons on the mesosphere and stratosphere.

Reference: OMI SO2Krotkov N.A., M. Schoeberl, G. Morris, S. Carn, and Kai Yang (2010) Dispersion and lifetime of the SO2 cloud from the August 2008 Kasatochi eruption, J. Geophysical Research, 115, D00L20, doi:10.1029/2010JD013984, 2010; Carn, S.A., A.J. Krueger, N.A. Krotkov, K. Yang, and K. Evans (2009). Tracking volcanic sulfur dioxide clouds for aviation hazard mitigation. Nat Hazards (2009) 51(2), 325-343, doi: 10.1007/s11069-008-9228-4 CALIPSO: Winker, D. M., M. A. Vaughan, A. H. Omar, Y. Hu, K. A. Powell, Z. Liu, W. H. Hunt, and S. A. Young, 2009: "Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms", J. Atmos. Oceanic Technol., 26, 2310-2323, doi:10.1175/2009JTECHA1281.1.

11.15.2010