505 
Symposium on Remote Sensing for Resources Development and Environmental Management / Enschede / August 1986 
Global vegetation monitoring using NOAA GAC data 
H.Shimoda, K.Fukue, T.Hosomura & T.Sakata 
Tokai University Research & Information Center, Tokyo, Japan 
ABSTRACT: In the last decade, the necessity of global monitoring of vegetations or bio-mass 
has become a more urgent matter. In order to prevent the large disaster which may be caused 
by vegetation decrease, accurate conditions or stage of the world vegetation should be 
monitored. The only satellite system and observation data which can be used for the purpose 
is TIROS/NOAA system and Vegitation Index Data(VID) made of AVHRR, respectively. The 
purpose of this study is to establish the method to derive a global vegetation map from a 
VID set. 
One data set was used in this study. A large shading effects mainly caused by sun angle 
deviations were first eliminated. The classification was done using a maximum liklihood 
method with four channels of VID. Training data composed of 67 categories were chosen 
according to bhe World Vegetation Map made by Preston James et al. 
After the classification, these 67 categories were unified to 17 categories. Then the 
classified image were transformed to longitude and latitude coordinates. As a result of 
this study, NOAA Vegetation Index Data were proved to be a suitable data for world wide 
vegetation monitorings. 
1. INTRODUCTION 
In the last decade, the necessity of 
global monitoring of vegetations or 
bio-mass has become a more urgent matter. 
Large forest areas in Asia and South 
America are dissapearing because of cut 
and burn agricultures as well as soil 
erosions. In Africa and also in Asia, 
Sahel areas are penetrated by deserts. 
The total amount of vegetation dis 
appearing- areas is estimated to be about 
3 00,000Kin for a year, which corresponds 
to be about the same of the area of Japan. 
These vegetation decrease in a world scale 
are causing heavy shortage of foods 
production, which results in many people 
starved especially in developing countries 
in Africa. It may also cause a world 
scale meteorological change. 
In order to prevent the large disaster 
which may be caused by these vegetaion 
decrease, accurate conditions or stages of 
the world vegetaion should be monitored. 
It is obvious that this kind of monitoring 
could be accompalished only through the 
use of earth observation satellites. 
However, past earth observation 
satellite data were not appropriate for 
this global monitoring purpose. Landsat 
MSS data has proved that they are very 
good tools for vegetation monitorings, but 
it is almost impossible to use those data 
in a global scale. There are two other 
operational satellite systems. They are 
TIROS/NOAA series satellites and weather 
satellites in geosynchronous orbits. 
However, the latter satellites are not 
appropriate for vegetation monitoring 
because of their wavelength ranges. They 
lack the near infra-red channels which are 
best for vegetaion discriminations. 
Thus, the only satellite system which 
can be used for this purpose is TIROS/NOAA 
system. The mam sensor of these 
satellites is AVHRR (Advanced Very High 
Resolution Radiometer) and it has one band 
in visible and one band in near infra-red 
regeon. Their repetitive rate is twice a 
day at least, and the ground resolution is 
about lKm at the nadir. This ground 
resolution is stil too high for monitoring 
purposes, because it means that we need 
about 500 million pixels to cover the 
whole earth, and also we must mosaic about 
18 paths of each ground coverage. 
But now, we have more convenient data 
for our purpose. It is called as a 
vegetation index data made of these NOAA 
data. In this data set, each hemisphere 
is composed of 1024 x 1024 pixels in a 
Polar Stereo projection, which is a 
moderate data quantity for data pro 
cessings and analyses. The purpose of 
this study is to establish the method to 
derive a global vegetation map from a NOAA 
vegetation index data set. 
2. NOAA SATELLITES 
The TIROS/NOAA sereies satellites were 
first launched in 1960 by NOAA (United 
States National Oceanic and Atmospheric 
Administration) for weather and ocean 
monitoring. Recently these two satellites 
were unified and called as NOAA satel 
lites . 
The orbit of this series satellites is a 
polar orbit with about 99 inclination and 
the altitudes are about 850Km. The main 
sensor is AVHRR and it has 4(5) spectral 
bands in visible, near and thermal 
infra-red regeon. The swath width of 
AVHRR is about 3000Km and one satellite 
covers the same area twice a day in 
ascending and descending mode.