Physical Oceanography Data Reduction Programs for the
8-169
PDP-8 (II)

C. K. Ross, R. Reiniger and A. B. Grant
Submitted by: Joann E.Gauan, Department of Energy, Mines
& Resources, Marine Sciences Branch, Dartmouth, Nova
Scotia, Canada

This system gives the capability of automating and improving
handling and processing of oceanographic data at sea.

It presents an oceanographic data processing system for use at
sea on a small computer with a basic configuration of 4K
memory, ASR-33 Teletype, high-speed paper tape reader/
punch and a 31 inch CalComp Plotter. The system was written:

1) to increase the speed, ease and accuracy of the
data reduction at sea.

2) to give quality control on the original data. This
allows malfunctioning instruments to be quickly
detected so that appropriate action may be taken.

3) to calculate various parameters which are used
by the oceanographer. The manual calculation
of these parameters is not practical because of
their complexity.

4) to digitize the data suitable for transfer to a
larger and more powerful shore-based system.

This PDP-8 oceanographic data processing system is capable
of accepting pressure, temperature, salinity, oxygen and
silicate as measured parameters. It is usual to have the
information necessary to calculate the pressure and temperature
shortly after the completion of an oceanographic station.
However, it is not possible to complete the determination of
the chemistry (salinity, oxygen and silicate) until several hours
later. Hence, the data input to the system is divided into
two parts. The first basic input contains the information from
the 'deck sheet' which is used to calculate the corrected
temperatures and observed pressures. A least square polynomial
is fitted to the observed pressures to give a final pressure at
each sampling depth. At this point a plot of temperature vs.
pressure may be obtained. To continue processing, it is
necessary to have the chemistry data which constitutes the
second basic input to the system. For each station the chemistry
data are combined with the pressures and corrected temperatures.
From these data the depth, specific volume anomaly, potential
temperature and density anomalies are calculated.

Certain approximations were made in the system because of
the limited core memory and to simplify the programming.
However, in all cases sufficient accuracy has been retained
to ensure meaningful results.

The following routines are included:

Temperature Formatting
Additions to Floating Point Package
Pack Thermometer Calibration
Pressure Curve Fit
Final Pass
DHUN
PLOPRM
Distance and Bearing
Formatting of Chemistry
Department PLOTCO

Catalog: November 1969