Volcanic SO2 emissions

On this page we describe the volcanic emissions inventories that are used by GEOS-Chem.

OMI-based volcanic emissions

Volcano emissions are obtained from NASA/GMAO. See the latest directory's README file in [1] for details on how these files were created.

The emission inventory is available as daily text (.rc) files in the format:

  ###  LAT (-90,90), LON (-180,180), SULFUR [kg S/s], ELEVATION [m], CLOUD_COLUMN_HEIGHT [m]
  ### If elevation=cloud_column_height, emit in layer of elevation
  ### else, emit in top 1/3 of cloud_column_height
  volcano::
  50.170 6.850 3.587963e-03 600. 600.
  45.780 2.970 3.587963e-03 1464. 1464.
  42.170 2.530 3.587963e-03 893. 893.
  38.870 -4.020 3.587963e-03 1117. 1117.
  ::

The text files can be read directly into HEMCO via the Volcano (formerly AeroCom_Volcano) extension. It can be activated in the HEMCO extension section:

  117     Volcano           : on    SO2
      --> Volcano_Source    :       AeroCom
      --> Volcano_Table     :       $ROOT/VOLCANO/v2019-04/$YYYY/$MM/so2_volcanic_emissions_Carns.$YYYY$MM$DD.rc

The Volcano_Source option was added to specify OMI or AeroCom emissions. If OMI-based emissions are used then the closest available year will be used if the simulation year is outside of the available time period.

Original implementation

Volcanic emissions of SO2 for 2005-2012 from Ge et al. (2016) are based on satellite measurements of SO2 from OMI (Ozone Monitoring Instrument) and ancillary information from the Global Volcanism Program. These data can be found in ExtData/HEMCO/VOLCANO/v2018-03/.

Cui Ge wrote:

Our degassing data are from Carn’s OMI retrieved data.

The difference for eruptive emissions is the 'cloud column height'. The emissions amount directly come from Carn’s, and the 'cloud column height' is from Smithsonian Institution Global Volcanism Program (GVP) report. Usually there are several records including radar, satellites and pilot reports for each eruption, we intended to get a better estimation by using the average of all the reasonable observations for each eruptive events. In the supplementary material of our paper, we did some sensitive tests about the uncertainties caused by different eruptive height and different eruptive activity duration.

Our data is only from 2005-2012, including:

• 48 eruptive volcanoes;
• 8 tropical degassing volcanoes.

If the elevation is the same as the cloud column height, the volcano is considered degassing, otherwise it's eruptive. Following the recommendation of Thomas Diehl, erruptive emissions are emitted into the top 1/3 of the emission plume. Most entries are degassing and there are only a few eruptive volcanoes each year.

--Melissa Sulprizio (talk) 17:17, 28 March 2018 (UTC)

References for OMI volcano emissions

1. Carn, S.A., K. Yang, A.J. Prata, and N.A. Krotkov, Extending the long-term record of volcanic SO2 emissions with the Ozone Mapping and Profiler Suite (OMPS) Nadir Mapper, Geophys. Res. Lett., 42, 925-932, doi:10.1002/2014GL062437, 2015.
2. Carn, S., Multi-Satellite Volcanic Sulfur Dioxide L4 Long-Term Global Database V3, Greenbelt, MD, USA, Goddard Earth Science Data and Information Services Center (GES DISC), Accessed: 28 Feb 2019, 10.5067/MEASURES/SO2/DATA404, 2019.
3. Ge, C., J. Wang, S. Carn, K. Yang, P. Ginoux, and N. Krotkov, Satellite-based global volcanic SO2 emissions and sulfate direct radiative forcing during 2005-2012, J. Geophys. Res. Atmos., 121(7), 3446-3464, doi:10.1002/2015JD023134, 2016. (PDF)

--Bob Yantosca (talk) 14:16, 22 March 2019 (UTC)

Previous issues that are now resolved

Bug fix for eruptive volcanic emissions

This update was included in GEOS-Chem 12.3.0, which was released on 01 Apr 2019.

Barron Henderson wrote:

I had previously brought up that I think there is a problem in the VOLCANO emissions. At the time a new volcano option was expected to supersede this option, but I think that VOLCANO is still the default.

The problem is with the eruptions being treated as cycling. The VOLCANO emissions use hemco's cycling option for both degassing and for eruptions. The last year in our dataset is 2009, which had a particularly active June. For example, 2009 June SO2 eruption mass is 4 times the average of the 2000-2009 June. The cycling option takes 2009 and applies it to *all* future years.

In pre-HEMCO emissions, the degassing was treated as cycling and eruptions were limited to available years. I think the old approach is preferable.

Obviously, an aware user can disable the cycling by replacing "C" with "R" for eruptions in HEMCO_Config.rc. I suspect, however, that many people are not thinking about this.

--Melissa Sulprizio (talk) 16:26, 28 March 2019 (UTC)