INTRODUCTION 
The information in this report was obtained from BI (bathythermograph) 
data collected at or near (within a radius of nine miles) the assigned positions of 
North Pacific Weather Ships. The observations are on file at the Scripps Institu- 
tion of Oceanography and were loaned to Texas A. & M. for this study. The methods 
of handling these data were given in detail in Technical Report No. 1 of this pro- 
ject, Some Methods Used in Representing Bathythermograph Data, but will be restated 
briefly here. 
For each year in which there are sufficient data at a given station to 
warrant this type of study, three time graphs have been drawn. ‘hese are: 
1) Depth of mixed layer and of water 2°F colder than the mixed 
layer; 
2) Temperature at selected depths; and 
3) Depths of selected differences from sea surface temperature. 
To obtain these time graphs of BT data, a procedure involving four separate steps 
was employed: 
1. Selection of cards. Onlyone card was used to represent a particular 
day. This card was one selected as being typical for that day, factors considered 
being sea surface temperature, depth of mixed layer, depth and nature of the ther- 
mocline, time of observation and general character of the curve. When possible, the 
observation made nearest to 2100 hours (GCT) was chosen. 
2. Reading of cards. Ateam of two people was used forall card reading, 
each reading being checked to assure accuracy. ‘Temperatures at ten chosen depths 
(0 ,30,50,75, 100,150, 200,250,350 and 450 feet) were read, with an agreement between 
readers of t0.1°F being required for each depth. The depth of the mixed layer 
(this depth being defined as the depth to a £ 0.3°F change from the temperature of 
the sea surface) and the depth of water 2F colder than the mixed layer were read, 
the required agreement in these cases being £3 feet. Finally the depths of se- 
lected differences from sea surface temperature were read, agreement again being 
3 £ 
s eet. 
3. Smoothing of data. ‘A running five-day average was determined to make 
a picture showing the nature of gradual changes with time. The value for a partic- 
ular day was obtained by averaging the value for that day with the two inmediately 
preceeding and the two following days. Exceptions occurred at the beginning or end 
of a series of days or at places where for one or two days there were no data avail- 
able. .Inthese cases four-day or, ina few cases, three-day averages were used. It 
should be noted that all curves are five-day running mean curves. 
4. Plotting of data. ‘The final step consisted of plotting the data in 
the form which appears in this report. It should be noted that only the values for 
the surface, 100, 200 and 350 foot depths have been plotted for temperatures at 
selected depths. Inthose cases where isothermal conditions exist, only the tempera- 
ture for the lowest depth has been plotted. Thus when the curve for a particular 
