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22 CHAPTER 2. ATMOSPHERE AND REMOTE SENSING
2.1.5 NOVAC - Network for Detection of Volcanic and Atmospheric Change
Christoph Kern
Abstract A novel passive DOAS instrument was designed and built explicitly for the measurement
of volcanic emissions in the scope of the NOVAC project. The first measurements with the instrument
prototype were conducted at Mt. Etna, Sicily.
Figure 2.5: Left panel: example results of an SO2 flux measurement on Oct. 2, 2006 az Mt. Etna.
Each graph represents a MAX DOAS scan through the volcanic plume. The integral over the entire
scan yields the amount of SO2 in the plume cross section. By measuring the wind speed, the flux can
subsequently be derived. The photo on the right shows the measurement geometry.
Background NOVAC is an EU funded project
started in October 2005 with the aim to establish
a global network of stations for the quantitative
measurement of volcanic gas emissions.
The project is based on a newly designed scanning
mini-DOAS instrument. Primarily, the instruments
will be used to provide new parameters
in the toolbox of the observatories for risk
assessment, gas emission estimates and geophysical
research on the local scale. In addition to this,
data will be exploited for other scientific purposes,
e.g. global estimates of volcanic gas emissions and
large scale volcanic correlations. Moreover, the instruments
also allow studies of climate change and
studies of stratospheric ozone depletion. In particular,
large scale validation of satellite instruments
for observing volcanic gas emissions will be possible
for the first time, thus bringing the observation
of volcanic gas emissions from space a significant
step forward [Khokhar et al. , 2005].
Methods and results During the first year of
the project, the main emphasis was on the design
and production of a fully functional prototype of
a scanning DOAS instrument specifically suited
for the measurement of volcanic emission fluxes.
The first measurements were conducted with this
prototype at Mt Etna, Sicily, Italy, in September
2006 (see Figure 2.5). During this measurement
campaign, it was established that the proto-
type is capable of measuring both SO2 and BrO
in volcanic plumes, as well as the wind speed inside
the plume. By combining this information,
BrO/SO2 ratios and real-time SO2 fluxes can be
compiled. The instruments are designed to operate
on a stand-alone basis over long periods of
time. Therefore, a large amount of data will be
compiled, and a database for archiving this data
was designed and tested. A fully functional search
mask was conceived to allow quick access to data
of interest.
Outlook/Future work The next step is to install
a larger number of NOVAC instruments at
the respective sites. Besides the studies mentioned
above, we also plan to conduct investigations
with respect to chemical components and
processes taking place inside volcanic plumes. After
validating satellite measurements of volcanic
emissions, worldwide monitoring will be possible
and global estimates of volcanic gas emissions
(SO2, BrO, CS2) will be compiled. These will allow
us to analyze the impact of volcanic emissions
on global climate change and tropospheric chemistry.
Funding EU Project: NOVAC
Main publications www.novac-project.eu