image that also presented, in the enhanced and pseudo- 
color images, a well-defined lens of warmer water in the 
position of the estuarine front. The lowest gradient was 
verified for the image of 1984 (20,6 °C - 22,7 °C), 
which showed no visual discrimination. 
The wider thermal amplitude detected in 1986 is 
possibly a consequence of the higher heat capacity of 
the dark water, rich in yellow substance. The 
comparison between the obtained values with 
simultaneous in situ water temperature measurements 
(routinely recorded by a station of the Oceanographic 
Institute-USP) presented a very good correlation. 
Similar results were obtained by Nichol (1993), and 
validate the use of band TM-6 as a secondary indicator 
of organic dissolved matter in estuarine fluxes. 
5, CONCLUSIONS 
Although cloud coverage is a widely know limitation 
for optical remote sensing in many coastal areas, this 
study demonstrated that satellite time series can 
effectively be used in the evaluation of estuarine surface 
fluxes and matter exportation through tidal inlets, even 
without simultaneous field missions. 
The importance in determining the main characteristics 
of these fluxes is multiplied in tropical and sub-tropical 
areas located in the western boundaries of the oceans, 
since the main source of nutrients that reach these 
coasts are related to the continental drainage. 
The characterization of estuarine influence in the 
adjacent coastal waters, obtained from TM time series, 
may also be applied in the monitoring of eventual 
environmental impacts in the region. The presented 
methodology also demonstrated a potential application 
for planning later field investigations. 
A previous knowledge of the oceanographic 
characteristics of the area is essential in this kind of 
work, and permitted the secure interpretation of the 
images. The synoptic vision offered by the satellite can 
lead to the identification of some geometrical aspects of 
the estuarine front that would be impossible to be 
obtained by traditional oceanographic sampling. 
From the integration of oceanographic and orbital 
information it was clear that the inner waters of 
Cananéia-Iguape Lagoonal-Estuarine system influenced 
the coastal area by the exportation of suspended 
sediments and dissolved organic matter, although local 
resuspension also occurs. The preferential northeastern 
redistribution of waters was also demonstrated. Further 
studies may confirm if there is a real seasonal control in 
the determination of the nature of transported 
material. 
80 
6. ACKNOWLEDGEMENTS 
The author sincerely thanks Prof. Dr. Valdenir 
Veronese Furtado and Prof. Dr. Teodoro Isnard 
Ribeiro de Almeida, from the University of Säo Paulo, 
for their genuine incentive and support to this 
research. 
7. REFERENCES 
Baban, S. M. J. 1993. Detecting and evaluating the 
influence of water depth, volume and altitude on the 
variations in the surface temperature of lakes using 
Landsat imagery. International Journal of Remote 
Sensing, 14(15), pp. 2747-2758. 
Bonetti Filho, J.; Almeida, T. I. R.; Conti, L. A.; & 
Furtado, V. V. 1994. Ladsat-TM and Digital Terrain 
Model applications in the study of abiotic parameters 
as a proposal to coastal monitoring. In: International 
Archives of Photogrammetry and Remote Sensing, Rio 
de Janeiro, Brazil, Vol. XXX, Part 7B, pp. 202-209. 
Bonetti Filho, J.; Conti, L. A. & Furtado V. V. 1995. 
Suspended Sediment Concentration Relation to Tidal 
Currents in a Microtidal Estuarine System. Anais da 
Academia Brasileira de Ciéncias (in press). 
Chavez, P. S. 1975. Atmospheric, solar and MTF 
corrections of ERTS digital imagery. In: American 
Society of Photogrammetry Fall Convention, Phoenix, 
USA, pp. 69-692. 
Froidefond, J. M; Castaing, P.; Mirmand, M. & Ruch, 
P. 1991. Analysis of the turbid plume of the Gironde 
(France) based on SPOT radiometric data. Remote 
Sensing of Environment, 36, pp. 149-163. 
Johnson, R. W. & Munday Jr., J. C. 1983. The marine 
environment. In: Colwell, R. N. (Ed). Manual of 
Remote Sensing. Vol. 2. American Society of 
Photogrammetry, Falls Church, pp. 1371-1496. 
Nichol, J. E. 1993. Remote sensing of water quality in 
the Singapore-Johor-Riau growth triangle. Remote 
Sensing of Environment, 43, pp. 139-148. 
Robinson, I. S. 1985. Satellite Oceanography. An 
Introduction for Oceanographers and Remote-Sensing 
Scientists. Ellis Horwood, Chichester, 455 pp. 
Witte, W. G.; Whitlock, C. H.; Harriss, R. C.; Usry, J. 
W.; Poole, L. R.; Houghton, W. M.; Morris, W. D. & 
Gurganus, E. A. 1982. Influence of dissolved organic 
materials on turbid water optical properties and remote 
sensing reflectance. Journal of Geophysical Research, 
87(C1), pp. 441-446. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B7. Vienna 1996