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| Jiuxin Shi and Yutian Jiao prepare the optical seawater profiler
for deployment. The optical instrument must be lowered at the side facing
the sun, and finding an appropriate opportunity with reasonable winds, sea
ice, clouds sun is very important for the deployment, but can be difficult
in the Arctic Ocean. Photo by Rick
Krishfield, WHOI. |
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| Yutian Jiao (middle) deploys the optical seawater profiler from
the forward A-frame with the assistance of Chief Officer John Jenner (near)
and Dan MacLean (far).
Photo by Jiuxin Shi, OUC. |
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| The surface optical sensor fixed at to the ship's railing near the
deployment location in order to provide a reference for the profiler when
lowered into the water. Photo by Jiuxin Shi, OUC. |
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Cruise - 2006 Dispatches
Calendar
Dispatch 11, August 15, 2006
By Jinping Zhao (Ocean University of China)
Light in the ocean
Jiuxin Shi and Yutian Jiao from the Ocean University of China are participating on this cruise to the Arctic Ocean to
observe the physical and optical profiles of seawater. The optical
properties of water respond primarily to incident solar radiation
(sunlight), and longwave radiation generated by the mass of the Earth.
Their objective is to establish the connection between physical and
ecological processes, which will be helpful to understand heating process in
the marginal ice zones and open water areas of the Arctic Ocean. Both
scientists have experience in both the Antarctic and Arctic regions in the
1990s and 2000s.
When the ship is stopped for a CTD station, Jiuxin and Yutian deploy
an optical profiler down to 120 m that measures the upward and downward
optical fluxes which are used to obtain the optical attenuation coefficient.
The instrument (produced by the Biospherical Instruments Inc.) measures the
fluxes at 18 wavelengths from 313 to 873 nm with high sensitivity, so as to
capture the weak light in deeper water. Another profiling instrument with
sensors of temperature, salinity, pressure, and fluorescence is combined
with the optical measuring profiler to measure the hydrographic properties,
chlorophyll and turbidity. Water samples at 5 m, 20 m and the depth where
the maximum amount of chlorophyll is observed, are filtered by different
films to measure the intrinsic optical absorptions by various substances in
water. In addition, a separate surface optical instrument is mounted to the
ship's railing in the air to measure the solar radiance simultaneously with
the underwater profiling.
So far this cruise, eighteen casts have been conducted by Jiuxin and
Yutian, including 4 on this day alone. The results analyzed together with
nutrient data obtained by the CTD chemistry group will establish linkages
among the physical, optical, chemical, biological processes. The OUC group
is dispatched by an Arctic project "Adjustment of thermodynamical structure
of Arctic Ocean under the background of global change and its feedback to
Arctic climate" funded by the National Nature Science Foundation of China.
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