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What Type of Instruments
were Used During the TOMS3F Campaign?
Ozone measurements were
taken in Fairbanks by several different instruments for 2 weeks during
the spring of 2001. The instruments used were 3 Brewer spectrophotometers,
2 Dobson spectrophotometers, ozone sondes launched daily, the Earth
Probe satellite carrying the Total Ozone Mapping Spectrophotometer (TOMS),
and several MicroTops spectrophotometers. High school students in Delta
Junction and Nenana took ozone measurements daily for two weeks with
a MicroTops spectrophotometer.
Spectrophotometers
Brewer Spectrophotometer
A ground-based instrument that measures the amount
of ozone in the stratosphere.
The Brewer spectrophotometer measures the amount of UV light from the
sun at 5 different wavelengths between 306 and 320 nm. Click here to
see a picture of a Brewer Spectrophotometer.
Dobson Spectrophotometer
A ground-based instrument
that measures the amount of ozone present in the stratosphere.
The Dobson spectrophotometer measures UV light from the sun from 2 to
6 different wavelengths between 305 and 345 nm. Click here to see a
picture of a Dobson Spectrophotometer.
MicroTops
A hand held spectrophotometer
that measures the amount of ozone in the stratosphere. The Sun is used
as the light source. By lining up the Sun in its window, ozone measurements
are made easily. The UV intensity is measured at 3 wavelengths between
305.5 and 320 nm. Click here to see a picture of a MicroTops.
Sondes
Ozone Sondes
Ozone sondes measure ozone
in the atmosphere by a chemical reaction. A weather balloon carries
the sonding instrument from the surface of the Earth to nearly 35 km
above the surface. Ozone sondes consist of a pump that pulls air into
a chamber that contains dilute potassium iodide. Another chamber contains
concentrated potassium iodide. The two chambers are connected by an
ion bridge. As ozone is pumped into the chamber of dilute potassium
iodide, a chemical reaction occurs that converts the potassium iodide
(KI) to iodine (I2).
2KI + O3
+ H2O => I2
+ O2 + 2KOH
The chemical reaction causes
the two chambers of potassium iodide to become out of equilibrium and
electrons flow through a circuit creating an electrical current. The
current is measured by the ozone sonding instrument. The sonding instrument
works like a battery that runs on ozone. The more ozone that reacts
with the potassium iodide the higher the electrochemical current. A
radio relays information back to a computer on the ground. Click here
to see a picture of an ozone sonde.
Satellites
Total Ozone Mapping
Spectrometer (TOMS)
The latest spectrophotometer
aboard the Earth Probe satellite launched by NASA in 1996. TOMS is a
spectrophotometer that measures the amount of UV light from the Sun
that is reflected off of the Earth. The TOMS spectrophotometer measures
UV light at wavelengths between 312 and 360
nm. The TOMS spectrophotometer
takes ozone measurements daily all over the world. To see the latest
images from TOMS go to the TOMS images
page or to the TOMS
web site.
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