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