To test potential satellite instrumentation, sea 

 surface temperature discontinuities have been de- 

 tected from aircraft in the visible, infrared, and 

 microwave regions of the spectrum. Infrared in- 

 struments have been used to map and measure 

 areas of strong thermal contrast. It also has been 

 possible under night-time, cloud-free conditions 

 to detect areas of sharp temperature contrast, 

 such as currents and upwelling, from NIMBUS 

 Satellite High Resolution Infrared (HRIR) imagery, 

 and several sea-surface temperature analyses have 

 been prepared.* 



TIROS-M, planned to be in orbit in 1969, will 

 have a two-channel radiometer on board, to 



An excellent summary of work in this field to date is 

 provided by Wamecke, G., L. M. McMillin, and L. J. 

 Allison, Ocean Current and Sea Surface Temperature 

 Observations from Meteorological Satellites, NASA Tech- 

 nical Report, Goddard Space Flight Center, Greenbelt, 

 Maryland, in press. In&ared instrumentation is reviewed 

 in Goldberg, I. L., 1968: Meteorological Infrared Instru- 

 ments for Satellite, NASA, Goddard Space Flight Center, 

 Greenbelt, Maryland. 



E LONGITUDE 



135° 140° 145° 150 155'160°165°170 175" 180 135M40° 145° 150 155' 160° 165= 170° 175 180° 



observe the atmosphere and ocean in both the 

 infrared band and the visible band. This will 

 provide daytime cloud/non-cloud discrimination, 

 and indicate when the infrared radiometer is 

 sensing the sea surface. A possible future develop- 

 ment is the laser altimeter to give precise measure- 

 ments of the mean sea surface from a satellite. 

 Such data, when used with appropriate equations 

 of motion for the ocean, could yield estimates of 

 major surface current speeds. 



Most available sea-state data are visual observa- 

 tions made aboard ships; for wdder coverage, 

 sea-state information is inferred from wind data. 

 Possible methods for determining sea-state from 

 orbital altitudes are based on changes in the 

 reflective properties of the ocean surface. Photo- 

 graphs of "sun gUtter" or "sun glint" have been 

 made from aircraft and sateUites. Another optical 

 technique, to yield a directional distribution of sea 

 slope as well as information about wave fre- 



EQUIVALENT BLACKBODY TEMPERATURE (• K) AND APPROXIMATE CLOUD TOP HEIGHTS 



<230":>11KM 



230"-240":9.5-11KM 



240"-250°:8.0-9,5KM 

 250'-260":6.5-8.0KM 

 260'-270":5.0-6.5KM 



270"-280":3.5-5.0KM 

 280"-290':1.5-3.5KM 

 290"-300-;0-1.5KM 



Figure 21. Comparison of satellite infra-red "picture" (NIMBUS II) and TV photograph 

 (ESSA 3) of typhoon Marie, Nov. 1, 1966. Infra-red data have been converted to cloud- 

 top height estimates (right) to provide analysis of visible cloud structure (left). (NASA photos) 



11-43 



