BT data collected over a satisfactory niomber of years, depending on approx- 

 imation req.uirenients, are quite accurate. Mean annual surface temperatures 

 computed from the BT data for the locations in this study depart only 0.8°F, 

 on the average, from mean annual surface temperatures computed from long- 

 range data (approximately 100 years) as shown in the annual temperature 

 chart (figure 2). This is a very good agreement when one considers the 

 small amount of data available for this study, especially in areas F, G, 

 and H, and allows considerable confidence in mean temperatures at ^00 feet 

 computed with the same BT data. Certainly, mean monthly temperatures may 

 show greater variation; however, time smoothing will eliminate many incon- 

 sistencies. In general, mean annual and monthly temperatures at 400 feet 

 computed with the BT data used in this study may be considered representa- 

 tive of these conditions. 



C. Mean Temperature Time Series 



Time -smoothed and imsmoothed mean temperature curves are shown for 

 the surface and 1|00 feet at OWS BRAVO in figure 3 and at OWS ECHO in figure 

 k. Curves for area H mean latitudes of 23.5°N, 30.5% 35-5% and 38.5°K 

 are shown in figure 5« 



Mean temperature distributions at the ocean weather stations and 

 along 58°N within area F have predominantly annual periods at the surface 

 and ^00 feet. The relationship between mean temperatures at the surface 

 and 400 feet at a given location may be characterized by (a) difference of 

 mean annual temperatures, (b) ratio of mean annual temperature amplitudes, 

 and (c) phase lag angle. This relationship varies with latitude; mean 

 annual temperature difference between two levels and mean annual temperature 

 amplitudes decrease with increasing latitude. The phase lag angle, quite 

 large in subtropical areas, approaches zero at high latitudes. 



In areas G and H, mean temperature distributions at 400 feet show 

 semiannual and shorter periods in addition to annual period. In area H 

 there is no evidence of phase lag angle variation, but latitudinal vari- 

 ation of mean annual amplitudes and differences is quite conspicuous. Data 

 were insufficient for comparing temperature distributions along two lati- 

 tudes in area G; however, it is assumed that variations of mean annual 

 temperature amplitudes and differences with latitude approach those which 

 occur at the ocean weather stations and area H. 



Normal probability fvinctions have been applied to obtain smoothing 

 operators for all curves. Seven discrete weights were used as ordinates 

 of the normal curve at intervals of standard deviation, cr , so that the 

 entire smoothing period {6a ) corresponds to 6 months. The values of 

 weights are: O.OOU, 0.054, 0.242, 0.400, 0.2^2, O.O5U, 0.004. Rounding 

 of weights to 3 decimals makes their siAm equal to unity, so that the mean 

 values of original and smoothed series remain unchanged. The principal 

 weight corresponds to the ordinate of the normal curve at the mean. Since 

 the smoothing operator is symmetrical with respect to the principal weight, 

 tbe phase angle of the mean temperature distribution remains unchanged. 



