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I. a ER = PN ase E EDEN MUR 
AN OPERATIONAL PROGRAM FOR MONITORING SURFACE TEMPERATURES 
OF LAKES AND COASTAL-ZONF WATERS IN CANADA FROM 
POLAR-ORBITING SATELLITE INFRARED DATA 
by 
G.J. IRBE and A. SAULESLEJA 
Atmospheric Environment Service 
4905 Dufferin Street 
Downsview, Ontario, Canada M3H 5T4 
ABSTRACT 
Surface temperatures of the Laurentian Great Lakes and Nova Scotia 
coastal waters in Canada are monitored regularly using infrared radiances in 
the 10.5 - 11.5 um region detected by sensors on board NOAA polar-orbiting 
satellites. Temperatures are corrected for atmospheric attenuation by 
radiative transfer calculations, using the Low Resolution Transmission 
(LOWTRAN) model of Selby et al. (1976), and local radiosonde cata for water 
vapour distribution in the atmosphere. The satellite-deriveG temperatures nave 
been found to have a root-mean-square difference of 0.6 C from temperatures 
measured at buoys. The performance of the method under diverse atmospheric 
conditions has been investigated in the course of operational temperature 
monitoring. Operational use of the method is limited to inland water bodies 
and coastal zones where radiosonde data are regularly available. 
INTRODUCTION 
Surface water temperature is an important parameter in many of the 
physical and biochemical processes occurring within a water mass and also in 
air-water interaction processes such as evaporation and air mass modification. 
Accurate and preferably regular synoptic-scale temperature data from water 
bodies of various sizes are required to assess and monitor these processes. 
During the past two decades the Hydrometeorology Division of the 
Atmospheric Environment Service (AES) of the Department of Environment of 
Canada has maintained water temperature data collection programs on the 
Laurentian Great Lakes. The Cata are used in forecasting local weather 
phenomena (e.g. occurrences of lake/land breeze, lake-effect snow, fog), in 
studies of local and regional climatic regimes, in predicting ice conditions on 
the St. Lawrence Seaway, in computing evaporation from the Great Lakes, and in 
other hydrometeorological studies. 
Initially water temperature data collection on the Great Lakes was 
accomplished by ships' cruises, followed in the mid-1960's by airborne 
radiation thermometer surveys (Richards et al., 1969; Irbe, 1972). In the 
early 1970's polar-orbiting sun-synchronous satellites, operated by the U.S. 
National Oceanic and Atmospheric Aéministration (NOAA), provided the 
opportunity for acquisition of truly synoptic water temperatures with full 
spatial resolution over large water surfaces. 
ATS has maintained a satellite data receiving station since the mid- 
1960's. Recording of digital data from NOAA satellites began in 1974, anc 
retrieval of surface water temperatures from satellite radiation thermometer 
(SRT) channel 4 (10.5-11.5 um) data was perfectec in 1977. Since 1980, surface 
temperature analyses from SRT data have been performec at two-to-three week 
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