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computations, which form the basis for the present study, were made manually. 

 The computational procedure has been described in technical reports (Laevastu, 

 1963), where also nomographs are given. Before averaging the meteorological 

 elements (reported by observing ships) by areas (e.g., 2 l/2° or 5° squares), 

 a subjective contouring of the distributions is necessary. This subjectivity 

 will be eliminated in computer programs of synoptic heat exchange now in 

 preparation at Fleet Numerical Weather Facility, Monterey. 



Detailed discussions of the sources and magnitudes of errors are given 

 in the aforementioned technical imports . It has been concluded that the 

 plausibility of the results obtained depends largely on the density of 

 meteorological elements reported over the ocean and on their analysis because 

 not the absolute values of the elements, but rather the differences between 

 the properties at the sea surface and some higher observation level (e.g., 

 8 to 10 meters), are used in most cases. Other difficulties, such as the 

 analysis of distribution of cloud cover, estimation of wind speed over the 

 sea, etc., are well known. 



In the evaluation and use of the computed results one must also be 

 conscious of the possible effects of short-term (diurnal and interdiumal) 

 variability of meteorological elements. However, as will be shown later, the 

 patterns of heat exchange components are usually larger in scale and relatively 

 persistent from day to day, changing in intensity and position in relation to 

 the change of corresponding surface pressure patterns, thus eliminating partly 

 the effect of short-term variations. The effects of diurnal fluctuations of 

 meteorological elements on computed heat exchange are discussed by the present 

 author elsewhere (Laevastu, I960, 1963)- 



Considering that rather large variability in meteorological conditions 

 occurs from day to day, that many of the heat exchange formulas use the dif- 

 ferences between the sea surface and the surface air properties, that the 

 relations of the influence of the elements in these formulas are often non- 

 linear, and that the formulas have mostly been worked out for and verified on 

 short-period (e.g., 2^4- hours) measurements and computations, it becomes 

 obvious that synoptic computations of heat exchange are usually not comparable 

 to heat exchange patterns computed with monthly or seasonal averages. The 

 above described condition is numerically illustrated in Table 2. Four values 

 of sea-air temperature and water vapor pressure are arbitrarily selected. 

 Furthermore, four values of wind speeds are taken in two different sequences, 

 which give two different values of sea-air exchange (q ) in the last two 

 columns. The average values of meteorological elements as well as the 

 averages of the computed sea-air exchange are giyen on, the sixth line. The 

 averaged Qg values are 59.3 and 182.5 g cal cm" 2i4-h" and illustrate the 

 differences in results caused by a difference in the sequence of wind speeds 

 used, even though the average wind speed is 6.25 m sec" in both cases. The 

 seventh line gives the Q value (10^4-) computed with the averaged values of 

 meteorological elements . It can be concluded from Table 2 and from a 

 knowledge of the variability of meteorological conditions that monthly and 

 seasonal computations can be expected to yield only an approximate distri- 

 bution of heat exchange patterns and their relative numerical values. To 



