TEMPORAL SPECTRAL MEASUREMENTS OF RICE CROP 
WITH THE GSFC MARK-II THREE BAND HAND-HELD RADIOMETER 
by 
A.J. CHEN 
H.T. WANG 
QC. TIN 
Department of Atmospheric Physics 
National Central University 
Chung-li, Taiwan 
Republic of China 
I. INTRODUCTION 
In the past, we had tried to utilize Landsat MSS data for agricultural resource 
assessment in Taiwan. Our case study indicated that over-all accuracy was about 
88% for estimating the acreage of the paddy field. As the land-use patterns and 
cultivated practices are very complicated in Taiwan, the spectral and spatial 
resolutions of the Landsat MSS data substentially limit its applications to 
various resource inventories. Recently, Taiwan Forestry Bureau scanner system, 
which consists of Daedalus DS-1260 Digital Scanner (12 channels), DS-1860 
Digital Multispectral Preprocessor, DS-1840 B/W Film Converter and DS-1813 
Color-Film Printer. The whole system is now in full operation. From the previous 
experiences, it becomes apparent that utilization of MSS data alone is not 
sufficient enough for practical applications. Ground-based in situ remote 
sensing studies are needed to better understand the physics between the natural 
materials and their reflectances as a function of wavelength. During normal 
operation, the airborne scanner scans a wild angle of + 40° across the flight 
path, and receives the reflected sunlight under a range of sun angles. It is 
thus important to determine the angular reflectance features of natural targets 
characterized by the bidirectional reflectance distribution function BRDF. If 
the BRDF exhibits significant anisotropy, the correction procedures must be 
followed to properly utilize the multispectral and multitemporal data sets taken 
under different illumination angles. In this report, we employ one GSFC Mark-II 
Three Band Hand-Held Radiometer, developed by NASA/Goddard Space Flight Center, 
for taking the bidirectional reflectance of rice crop over its various 
growing stages. The consensus is to find out the features of the bidirectional 
reflectance for future utilization of air-borne MSS data.