Measurement of Seawater Temperature at Carna, Co. Galway, Ireland (1974-2003)

Sea water temperature was monitored on a continuous basis from the start-up of the laboratory at Carna (Co. Galway) in July 1974 until 2003, when a rebuild of a section of the laboratory removed the recorder. The sea water intake pipe extended about 100m beyond the end of the pier, the pipe running in gullies between the rocks, weighed down with concrete weights to a point beyond the low water springs mark. It was 4inch Hydrodare pipe, pinned along the outside of the pier wall, to the lab, where it entered the building through a constant head arrangement of the pipework. The total distance from intake to the lab was about 200m. A pump house was built on the seaward side of the pier. The pumps were centrifugal patterns, and the pumps were change dover the years as larger volumes were required. The minimum flow rate was 600L per minute. This flow would increase slightly on a high tide. After installation, for a period of about three months, the displayed temperature was checked against the temperature at the tide edge and no discernible difference was noted. Pipe intake at approx. 53° 18.55'N, 9° 49.75'W. The measurement device was initially a Cambridge Instruments 10 inch circular chart recorder fitted with a seven day rotation motor. The first measurement system was a MIS expansion probe, connected to the recorder by a capillary, the actual measuring bulb was contained in a stainless steel pocket fitted into the incoming seawater line. On changing the chart, the temperatures were extracted by hand and then typed up. The temperatures were taken for midnight, 6am, noon and 6pm. Where the clocks went forward in Spring for Summer Time or back in Autumn to GMT, the changeover on the chart would usually have been on the following Monday morning about 9am. When the recorder pattern became outdated around 1998, and spares difficult to obtain, the recorder was changed for a Cambridge Instrument P100L, 4 inch strip chart recorder. The measuring probe was a Pt100 platinum resistance thermometer, BS1904 specification, again fitted into a stainless steel pocket fitted into the supply line. The charts on this instrument were changed on a fortnightly basis and again, the six-hourly temperatures extracted by hand and typed up.