International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B7, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
    
  
  
  
  
  
  
  
  
  
  
  
Figure 1. HJ-1 CCD and Radarsat-2 image of study area, (a) HJ-1 CCD (RGB normalization false color composition), (b) 
Radarsat-2(PauliRGB composition) 
Data source Acquisition data | Spatial data(m) Signal characteristic Other notation 
HJ-1 CCD 2010-08-04 30x30 spectral reflectance four band number 
RADARSAT-2 2010-08-01 12x8 backscattering coefficient | fine quad-polarization 
Table 1. Overview of RADARSAT-2 image and HJ-1 CCD image 
2.3 Situ measured data 
Coincident with the image, sea surface measurement data, 
including TIN and ocean surface condition (i.e., wind speed, 
wind direction, wave height and wave direction) were collected 
from Environmental Protection Department, the government of 
the Hong Kong Special Administrative Region 
(http://sc.epd.gov.hk). 
3. METHOD 
3.1 Selection of input variables 
In order to improve the accuracy of estimating TIN, the input 
variables which were relative sensitive to TIN were selected. 
To ascertain the sensitivity of the spectral parameters and 
polarization parameters to TIN in the study area, a series 
quadratic fit model were conducted from TIN value with 
spectral parameters and polarization parameters. In general, for 
polarization parameters, our results showed that HV has a 
06r 
d os. Ra 
E i T t 
# 0.4 "st E ose 2, io 
  
TIN(mg/L) 
= n 
Sin 
EFA n £x 
Qum 
    
  
  
1 : ; 
6.00 001 02 0.03 (£04 005 
Band4 
Figure 2. 
     
Relationship between different optical parameters, polarization parameters and TIN 
strong non-linear relationship with TIN, the correlation 
coefficient (R?) being 0.54; VH correlate positively to TIN, R° 
with 0.36 (Figure 2). 
For spectral parameters, Normalized Difference Spectral Index 
(NDSI) was proposed and computed by 
NDSI - (R, - R)/ (R, - R) (1) 
Where R, and R, are reflectance of 1” band and 
reflectance of 4™ band for HJ-1 CCD image. Our results 
indicated that single band, namely, reflectance of Band 4 was 
positively correlated with TIN, R? of 0.35; NDSI has 
correlation with TIN, R? with 0.32 (Figure 2). 
In sum, VH, HV, Band 4 and NDSI were selected as the input 
variables of model for estimating TIN in sea surface. 
  
  
  
4 AL [0 4.2 64 
NDSI