led 
It was found by trial that hovering over the water surface 
at about 60 ft altitude did not disturb the water environ 
ment. At that altitude MARTEK sensors were lowered in the 
water for in situ water parameter measurements. At the same 
time the other two crews on board the boat were also measur 
ing same parameters. The following table lists the measured 
values as taken with 
a- Airborne MARTEK MARK II equipment 
b- Seaborne MARTEK MARK II equipment 
c- Conventional procedures on board the boat. 
The last column to the right give the standard deviation 
sd of the three measurements. 
TABLE I 
MARTEK 
MARTEK 
Conven- 
Mean 
sd 
airborne 
seaborne 
tional 
Temperature 
(°C) 
Surface 
28.5 
28.5 
28.89 
28.63 
.19 
Bottom 
28.0 
28.6 
28.60 
28.40 
. 16 
Dissolved 
Oxygen(ppm) 
Surface 
5.8 
5.2 
5-57 
5.52 
.25 
Bottom 
5.2 
5.1 
5.52 
5.27 
.18 
Conductivity 
(m. mhos) 
Surface 
61.0 
62.0 
66.4 
63.13 
2.34 
Bottom 
62.0 
62.0 
66.6 
63.53 
2.17 
pH 
Surface 
8.12 
8.14 
8.15 
8.14 
0.01 
Bottom 
8.11 
8.08 
8.17 
8.12 
0.04 
DISCUSSION 
The list of observations given above indicates that, except 
for conductivity, the data sensed with physical sensors from 
helicopter or from a boat are in congruence with those 
measured in conventional techniques on board a boat. Stan 
dard deviations of 0.2°C for temperature, 0.2 ppm for dis 
solved oxygen and 0.05 for pH are exceeding the accuracy 
needed for correlation of remotely sensed data with environ 
mental conditions. 
About conductivity, there is a discrepancy of about 4.5 mil- 
limohs between Martek records and conventional method result. 
The difference is untolerable as it is interpreted in sali 
nity difference of about 4000 ppm. In fact this list is a 
copy of the one acquired immediately on board the boat and 
the plane at the epoch of the experiment. Conformity of both 
Martek results gives tendency that the results of physical 
sensors are more reliable. This tendencv has been streng-