Bull. Volcanol. Soc. Japan
Vol. /, (,**1) No. ,, pp. +*/ῌ++,Letter

A Compact Ultraviolet Spectrometer System (COMPUSS) for Monitoring
Volcanic SO, Emission: Validation and Preliminary Observation.
Toshiya MORIῌ, Jun-ichi HIRABAYASHIῌῌ, Kohei KAZAHAYAῌῌῌ, Takehiko MORIῌῌῌ,
Michiko OHWADAῌῌῌ, Makoto MIYASHITAῌῌῌῌ, Hideki IINOῌῌῌῌῌ
and Yasuhiro NAKAHORIῌῌῌῌῌῌ
(Received, July +2, ,**0 ; Accepted, February 0, ,**1)
A compact and handy system for measuring SO, ﬂuxes from volcanoes is newly built using a miniature UV
spectrometer. This COMPact Ultraviolet Spectrometer System (Hereafter referred as “COMPUSS”) is muchsmaller and lighter than a correlation spectrometer (COSPEC), which has been used for SO, ﬂux measurementsfrom volcanoes over -* years. Validation of the COMPUSS was carried out comparing COMPUSS and COSPEC
instruments at Sakurajima and Miyakejima volcanoes by car and heliborne traverse method, respectively. Our
results show that agreement of the SO, ﬂux between the COSPEC and the COMPUSS data is vouched for traverse
measurements. The COMPUSS has much advantage compared to the COSPEC for volcanic SO, ﬂux measurements, because of its portability and possibility for further improvement of the system.
Key words : SO, ﬂux, DOAS, UV spectrometer and COSPEC+. Introduction
For the last -* years, correlation spectrometer (COSPEC) has been used as the only method for groundbased remote sensing to measure sulfur dioxide emission
rate from volcanoes and had a prominent contribution
on the progress in recent volcanology. The COSPEC
was ﬁrst designed for monitoring industrial emission ofSO, and NO, in +30*’s (Ho# and Millan, +32+) andlater used for monitoring volcanic SO, emissions byvarious researchers (e.g., Mo#at and Millan,+31+ ; Stoiberand Jepsen, +31-). Integrated COSPEC measurements
showed that correspondence of SO, ﬂux with magma
discharge rates at Unzen volcano, Japan (Hirabayashi etal., +33/) or with seismicity and ground deformation at
Soufriere Hills volcano, Montserrat (Watson et al., ,***).
In the beginning of this century, a remarkably small
miniature ultraviolet spectrometer was introduced andused successfully to volcanic SO, ﬂux measurements(Galle et al., ,**,). This compact and low-cost UVῌ Laboratory for Earthquake Chemistry, Graduate School

spectrometer system o#ered a chance to carry out various kinds of new monitoring methods. Owing to its
compactness and portability, the instrument enabled us
to make walking traverse measurements (McGonigleet al., ,**, ; Oppenheimer et al., ,**.). At Soufriere
Hills volcano, continuous (day-time) measurements ofSO, ﬂux is carried out using two scanning systems withthe miniature UV spectrometer (Edmonds et al., ,**-).
Several groups developed new methods for measuring
the plume speed, which has been always a fundamental
problem for ﬂux estimation, by the use of the miniature
UV spectrometer (McGonigle et al., ,**/ ; William-Joneset al., ,**0). Under current situation, each researcher
builds their own systems using the spectrometer (Galleet al., ,**, ; Horton et al., ,**0 ; McGonigle et al., ,**,).
In ,**,, we started to develop a Japanese version of theminiature UV spectrometer system. The COMPUSS
and its operating software are specially designed focusing on easy handling for measurements and on availabil-Japan.
of Science, University of Tokyo, Bunkyo-ku, Tokyo, ῌῌῌῌῌ Sapporo District Meteorological Observatory, Japan++-ῌ**--, Japan.
Meteorological Agency, Sapporo, Hokkaido, *0*ῌ***,,
ῌῌ Volcanic Fluid Research Center, Tokyo Institute ofJapan.
Technology, Meguro-ku, Tokyo, +/,ῌ2/++ , Japan. ῌῌῌῌῌῌ Chubu Aviation Weather Service Center, Japan Meteoroῌῌῌ Geological Survey of Japan, National Institute of Adlogical Agency, Tokoname, Aichi, .13ῌ*22+, Japan.
vanced Industrial Science and Technology, Tsukuba,
Ibaraki, -*/ῌ2/01, Japan.
Corresponding author : Toshiya Moriῌῌῌῌ Seismological and Volcanological Department, Japane-mail : mori@eqchem.s.u-tokyo.ac.jp
Meteorological Agency, Chiyoda-ku, Tokyo, +**ῌ2+,,,