SIMBAD RADIOMETER - INSTRUCTIONS
The SIMBAD radiometer measures direct sunlight intensity by viewing the
sun, and water-leaving radiance by viewing the ocean surface at 45 degrees
from nadir and 135 degrees from the sun's vertical plane. The wavelengths
are 443, 490, 560, 670, and 870 nm. It is powered by batteries, which allow
about 6 hours of continuous use. Accessories include 1) a GPS, 2) a cable
for charging the batteries, and 3) a rs232 cable to download the data.
Operating the instrument
1) Connect the GPS to the instrument, and secure the GPS outside, on a ship
structure. The GPS has a magnetic bottom, that allows easy fixation on the
ship.
2) Put the option knob on position PC, and turn the instrument on. The knob
must be on the PC position before turning the instrument on. The two red
and yellow lights will blink alternatively until the GPS is initialized.
This may take up to two-three minutes. When the GPS is initialized, there
is a beep, and all the lights go off.
3) Select one of three scenarios/modes, namely DRK (measurement of dark
current), SUN (sun viewing), or SEA (ocean viewing). The experimental
procedure is to make, consecutively, one DRK measurement, three SUN
measurements, three SEA measurements, and one DRK measurement.
-DRK mode: Put knob in DRK position. Place cardboard at the end of
collimator and/or dark cloth, so that no light can enter the instrument.
Press the red button. The two red lights will blink, until the end of the
measurement. The measurement lasts 20 seconds. A beep indicates the end of
the measurement. After the measurement, put the knob back in the PC
position.
-SUN mode: Put knob in SUN position. Aim at the sun, and press the red
button. The measurement lasts 10 seconds. A beep indicates the end of the
measurement. After the measurement, put the knob back in the PC position.
-SEA mode: Put knob in SEA position. Go to the side of the ship, and aim at
the ocean, after having approximately positioned the instrument at 135
degrees from the sun's vertical plane. The two yellow lights will both be
on when the nadir angle is 45 degrees. The two red lights will be on when
the polarizer is in the correct position. Thus, the desired position for
the radiometer is obtained when the four lights are on. Press the red
button. The measurement lasts 10 seconds. A beep indicates the end of the
measurement. Sometimes the red lights do not indicate properly the
polarizer position. Therefore is preferable not to refer to the red lights
for the polarizer position, but rather to refer to the horizon. After the
measurement, put the knob back in the PC position.
4) Check that the knob is in the PC position. Turn off the instrument. The
instrument should be in the PC position before turning it off.
Downloading the data
Install appropriate software (provided on a PC diskette) on a PC: 1) copy
"bwcc.dll" file in c:\windows\system\; 2) create directory for SIMBAD; and
3) copy diskette files into directory. Software works with windows 3.1 or
95. Check whether the right com port is used (com port is set in file
"simbad.ini"). Connect the rs232 cable to the instrument and to the PC. Put
the knob in PC position. Turn the instrument on (do not connect the GPS to
the instrument). Press the red button to stop the automatic GPS
initialization. Run the SIMBAD executable program, and follow instructions
on the menu. Save the data on a PC diskette. Delete the data from the
internal memory. Turn off the instrument.
Charging the batteries
After use, turn off the instrument, secure the instrument, and connect the
charging cable to the instrument and to an electric outlet (110V). The
instrument must be turned off for the batteries to charge. Charge the
batteries all night, from sunset until the next morning.
Cleaning the Optics
The SIMBAD exterior optics should be cleaned regularly, typically before or
after each series of measurements (once a day when measurements are made),
with non-abrasive paper and special cleaning solution. Do not put cleaning
solution directly on the optics, because it may leak into the internal
optics, but on the abrasive paper.
Experimental Procedures
The SIMBAD measurements should be made during daytime, when the sun disk is
not obscured by clouds, outside foam and whitecaps. Ideally, weather
permitting, the measurements should be made 1) at each station during
daytime (if the ship stops offshore), and 2) while the ship is moving
around local noon (time of SeaWiFS overpass). The best ship location to
make the measurements is the bow. Since SIMBAD does not like sea water, "en
route" measurements should be made only when there is no risk of wetting
the instrument. If sea water gets into the instrument, immediately put the
instrument in PC position, turn off the instrument, and clean the exterior
optics (see above).
The following meteorological data should be acquired concomitantly,
whenever possible: date, time, lat., lon., cloud cover and type, air
temperature, dew point (or wet bulb) temperature, surface pressure,
visibility, wind speed, wind direction, whitecaps (none, low, moderate, or
high), water temperature, surface chlorophyll, phaeo ( log sheet). Some of these data
may be available from the bridge log.
Contact:
Robert Frouin, SIO:
rfrouin@ucsd.edu,
858/534-6243 (voice), 858/534-7452 (fax)