)
atmosphe
estimat-
sea state,
ts are
VATY
his factor
be the
tel pro-
is author
water sur-
2 when
for orien-
emissivi-
ed, the
an 1mm
o at a
water
ag dimensio
2 differen
Jotivity of
For the
lux from
Jed it
lis:
19)
= 1301. —
uhere: - Barnes PRT-5 measured temperature
T
B
Tg + A Orr z Tob = blackbody temperature
Top "A am? T (2) = radiation temperature at z meters
T (z) + oA. = T_(0) = radiation temperature at sea sur-
S a 8 face
T. (0) «A p = T, = skin temperature (i.e. that of the
8 upper water boundary layer from which
emerging infrared radiation is mea-
; sured)
To + A; = T = water bulk temperature (i.e. that mea-
sured in situ by conventional methods.)
Experimental Results
A) Data collection
To test tha suitability of the procedure data uere taken
from the oceanographic mission OELTA 77, which took place during
July 1977. The mission had as main goal the microstructural
study of coastal water characteristics in the region of the Ebro
delta and St, Jorge's bay. The area is schematically represent-
ed in figure § The oceanographic parameters of interest were
measured by an in situ oerating marine unit on a continous way,
thus allowing a comparison with remctely sensed data. The marine
unit operated simultaneously to the overflights of a CASA 212
aircraft from the cartographic service of the Ministery of Air.
B) Intervening factors: Evaluation of errors -
A data set corresponding to one day of observations has
been used to test the suitability of the global correction under
the above mentioned assumptions. The correcting factors uere
found to have the following mean values:
À corr = + 0 80
À a = ” 0,33 ;
Ar = 0 (for emissivity was assumed to be unity)
A am = = 0.20
^i = =~ 0,52
All this values are given in degrees centigrade. From the above.
corrections it results that T. is related to T, and that the
relation is lineal and that tlle final factor i8 -0,258C. Never-
theless, the calculatad water bulk temperature appears, in the
average, to be 0.29C greater then the ground measured temperature.
