Symposium on Remote Sensing for Resources Development and Environmental Management /Enschede /August 1986 
© 1987Balkema, Rotterdam. ISBN 90 6191 674 7 
Monitoring environmental resources through NOAA’s polar orbiting 
satellites 
Joan C.Hock 
National Oceanic & Atmospheric Administration (NOAA), National Environmental Satellite Data & Information Service, 
Assessment & Information Services Centre, Washington, D.C., USA 
ABSTRACT: Satellite imagery in combination with surface weather observations can provide a potential tool for 
evaluating ground and water conditions throughout the world. In order to monitor the economic impacts of 
anomalous weather, the Assessment and Information Services Center (AISC), of the National Environmental 
Satellite, Data, and Information Service (NESDIS), National Oceanic and Atmospheric Administration (NOAA) 
integrates satellite data, geographic information, agronomic, and economic models to monitor both land and 
marine resources. Such assessments can provide government officials with an early warning of crop failure in 
order to mitigate potential climate impacts and reduce climate vulnerability. 
SATELLITE ASSESSMENTS AND TRAINING FOR AGRICULTURE 
IN THE TROPICS 
AISC currently provides climatic assessments on food 
security of developing countries in the Caribbean 
Basin, Africa, South and Southeast Asia, and Central 
and South America. The program is based on weekly 
rainfal1/weather analyses and climatic impact 
assessment models for more than 400 agroclimatic 
regions. Regional rainfall estimates are determined 
from ground station reports received through the 
World Meteorological Organization communications 
network and satellite cloud data. The assessment 
program utilizes NOAA's polar orbiting and 
geostationary satellites for early warning of 
environmental problems. 
Many of AISC's current capabilities resulted from the 
1973 LACIE program (Large Area Crop Inventory 
Experiment) and later AgRISTARS (Agriculture and 
Resource Inventory Through Aerospace Remote Sensing). 
AgRISTARS contributed to the development of 
techniques for monitoring the extent and condition of 
major crops worldwide. In this cooperative effort, 
the U.S. Department of Agriculture (USDA), the 
National Aeronautics and Space Administration (NASA), 
the Department of Interior (DOI), and NOAA, 
collaborated in crop identification and area 
measurement using Landsat data. Special products 
included daily estimates of precipitation, 
insolation, maximum and minimum temperatures, 
vegetation indices, and snowcover. From this initial 
effort, NESDIS has continued to develop techniques 
that use AVHRR data from NOAA polar orbiting 
satellites to assess crop stress and drought 
conditions in the developing world. 
Assessments on the status of agricultural production 
can be provided at least one month prior to the crop 
harvest. This lead time may permit decision makers 
to adjust marketing and pricing policies, import and 
export plans, and economic programs for farmers. 
Drought/disaster preparedness plans can also be 
established to mitigate climatic impacts through 
improved agricultural practices, selection of drought 
resistant crops, and optimum planting dates. In the 
end, such assessments or monitoring activities reduce 
climate vulnerability and lower the risk of crop 
fai 1 ure. 
Since 1976, the Assessment and Information Services 
Center (AISC) has significantly expanded reliance on 
satellite imagery for agricultural monitoring. 
Training courses have been designed for in-country 
scientists to utilize meteorological data augmented 
by satellite imagery. Visible Channel 1 with a 
wavelength band of .58-.68 jpm is ideal for monitoring 
daytime clouds and for surface mapping. 
Near-infrared Channel 2 with a wavelength band of 
.725-1.10 gm is ideal for surface water delineation 
and vegetation assessment. Channels 3, 4, and 5 are 
thermal IR channels appropriate for cloud and surface 
temperature determination. Each channel is used to 
emphasize its strength. There are two key satellite 
products in the NOAA/Agency for International 
Development (AID) assessment program: (1) 
precipitation estimates, and (2) color graphic 
displays for agricultural and vegetation monitoring 
in the developing world. Both products provide 
monitoring information on the condition of land 
resources. 
To estimate rainfall, the Center uses the visible and 
thermal infrared channels of the polar orbiting 
environmental satellites. Assessors rely on 
satellite data to augment ground station 
precipitation reports. Computer generated rainfall 
estimates are produced and the assessors have the 
opportunity to change the estimates, if needed. The 
VAX computer reads daily worldwide Mercator AVHRR 
visible, day infrared, and night infrared data. This 
machine generates histograms of the data distribution 
over defined crop growing areas. Rainfall estimates 
are then produced by determining the areal coverage 
of clouds in predefined class intervals in the 
histograms. The assessors can view both the 
satellite scenes and rainfall estimates using the 
Log-E image processor. The histograms and images are 
then transferred to the VAX data base for assessment 
purposes. These satellite precipitation estimates 
are also input to agricultural crop-yield equations. 
A second product that is used in agroclimatic 
assessments is the vegetation index. Both PSG (Polar 
Stereographic) and GAC (Global Area Coverage) AVHRR 
data, in combination with crop calendar information, 
are used for assessments. The difference in 
reflectance between Channel 2 and 1 provides a 
signature of the plant vigor. Channel 1 responds to 
reflected sunlight in the long wave length visible 
region, and Channel 2 records near infrared reflected 
sunlight. Visible Channel 1 is relatively 
insensitive once initial greenup of vegetation has