294 to 301°K , or a difference of about 7°K, which is in agreement with the tem- 

 perature gradient as analyzed from the IR data. 



Upper air data from the Japanese station at Tateno indicated a hot and moist 

 troposphere, with a slight subsidence inversion at 820 mb. Taking 275 K as the 

 average temperature of the field, and considering the 20 minimum IR sensor 

 nadir angle of the pass, an approximate atmospheric attenuation correction of 9 K 

 was determined. This, plus a 2 K sensor degradation correction, adjusts the 

 average observed temperature to 286 K, still short of the 300 K indicated in mean 

 monthly charts for this region. 



Conventional ship measurements of SST were extracted from the National 

 Meteorological Center (NMC) charts over a five day period centered on the date 

 of this pass (II August). These conventional measurements were generally in 

 line with the climatological values, leaving the approximately 14 discrepancy in 

 the IR data unexplained. The ship data were converted to degrees Kelvin, and then 

 reduced by 25 K to simplify the comparisons with the IR data. (The conversion of 

 the ship data to a Channel 2 base, rather than vice versa, was used to reduce the 

 amount of data to be modified, since only a very limited amount of conventional 

 data was available. ) The modified ship data are plotted in Figure 5-3. Considering 

 the lack of dependability of typical ship reports of SST, and the fact that the ship 

 data cover a five day period, the two types of data correlate quite well. It seems 

 reasonable to infer that, given a suitable conventional observation to serve as a 

 benchmark, absolute temperatures as well as temperature gradients may be deduced 

 from the TIROS IR measurements. 



5. 2. 2 Yellow Sea Case 



The FMR tapes for this case were processed in the same manner as those for 

 the Kuroshio Current case discussed in the previous section. Again the noise level 

 was such that averaging in 1 squares was necessary. When relative changes in the 

 Channel 5 data were used to eliminate cloud points, only a narrow clear strip re- 

 mained, running southwestward from the southern tip of Korea to about 25 North. 



The data taken from Pass 780 of TIROS VII, at 0417 Z on 1 1 August 1963, 



revealed an unpatterned, essentially isothermal field with an average uncorrected 



o 15 



temperature of 279 K. Climatological maps reveal a temperature gradient of 



less than 2. 5 K from the tip of Korea to 2 5 North. 



23 



