oretures 
Lerres- 
[on (1). 
Jiometer 
indicated 
jing of 
/ some 
3rence 
nain al- 
19 radia- 
and iii) 
3e The 
3. of. a 
interface 
‘ong, the 
jeen that 
in the 
|'e kinetic 
jit with 
surements 
in the 
| such as 
'er, than 
ig it is 
in tne 
face, 
Ss respect. 
‚he con- 
tter re- 
at flight 
se of the 
indicated 
to or 
perature 
| the sur 
f -3DO m 
to + 0.5 
n accor- 
even of 
he many 
given 
his paper 
included 
olution 
of a 
p yin- 
tortions 
ons vith 
water 
account 
ture rea 
- 1295 - 
ding, for otherwise icorrect thermal patterns may result in an 
inaccurate thermzl pictureof the area under investigation. The 
problem of calibrating the radiometer has beon treated by other 
authors (10), (11). Tuo methods ere generally used: thes inter- 
nal calibration method and the correl:tion met::cd. The last is 
relatively simple but has a serious drawdzck since severel 
flight paths over the marine unit ars nerdad in order to assure 
a good calibration. The internal calibration method is applica 
bles when the used radiometer is a scanning radicreter; thus that 
it won't be considered here. For the Darnes radiometer however, 
no calibration procedure was found with exception of thes attach 
ed with the operations manual -in which flight altitude effects 
are not considered- or the given by GALLAGHER (12), who also 
doesn't consider atmospheric influence. Only two articles (5), 
(9) referred to global correction considerations applicable to 
our case. This article gives a method of global correcting ra- 
diometric data by considering ail the up tó nou neglected inter 
vening factors. 
Background 
The use of remote sensors operating in the thermal portion 
of the electromagnetic spectrum was first initiated for civil 
work in 1953 (13), but it is only in the last decade thst ther- 
mal infrared remote sensing became oporstionsi on a routine ba- 
sis for measuring accurate sea surface temperature. 
There are two general types of radiometers operating either 
in the 8 - 14 pm or in the restricted 5,5 - 11.5 um uavelenath 
bands. The basic difference between them is that one scans 
across the monitored area whereas the other m»ssures only tne 
incoming radiation from the overfloun spot. We shall be con- 
cerned with the utilization and criticzl revizw of tha secand 
type of radiometer. The relationship bstyesn the tuo types of 
radiometers are discussed in (5) and won't be treated here. 
Radiometer 
In this study we used a Barnes Precission Radiation Ther- 
mometer model PRT-5. The characteristics of this instrument 
are given belou: 
« wavelength range: 8 - 14 um limited to 9.5 - 11.5 pm 
by a band pass filter 
e field of vieu: 29 nominal 
»« temperature range: a) -309C to «109€ 
e] -109C to «409C (used here) 
c) 4209C to +8GQC 
« sensitivity: over 0 - 25°C range better than 0.1 
. response: 0.5 to. 30 cps. s 500 to 5 millisec. 
« lens: 10mm Irtran 2 f/2.8 
« detector: bolcmeter type 
« output: 0 - 5V with 10Kohm impedance