CLOUD IMAGES

Directory Structure:
Under the name of each vessel are a series of directories, being the dates when cloud photos were taken. Under each date are a series of files, each one a JPEG image scanned at a resolution of 500 DPI, and about 40 Kb size. The files are e.g 09janf14.jpg, which indicates the film STARTED on the 9th jan (UTC) on Franklin (f=Franklin, w=Wecoma and m=Malaita), and the 14th exposure in sequence. The date and time recorded on this photo are 10 2:01 which is actually midday local time. Note that local midday may not always be on the 14th frame - it depends what time the operator started the camera in the morning!

The Cameras:
Two Canon automatic cameras, with fisheye lenses and waterproof enclosures, were kindly provided by Prof. Ann Henderson-Sellers and Dr. Kendall McGuffie, then of Macquarie University, Sydney. Their technique using these cameras is described in EOS, Trans. AGU, Vol. 69, No 28, pp 713-720, July 12, 1988.

During COARE, one camera was carried on R/V Franklin, and the other on R/V Wecoma. A third camera owned by the Oak Ridge group was carried on S/V Malaita. Franklin's camera was mounted above the wheelhouse, 14m aft of the bow and 3m inboard from the starboard side, 12m above sea level. Franklin is 55m long overall with 11m beam. Wecoma's camera was about 10m forward of the stern, about 1m inboard from the starboard side and about 8m above sea level. Being aft of the smoke-stack may explain what appear to be specks of soot on some images. Wecoma is 56.4m long and the beam is 10.1m. Position of Malaita's camera is unknown.

The cameras were set to take a photograph on the hour and half-hour throughout daylight hours. So there were about 24 exposures taken each day. The date and time stamps recorded on the film are UTC. Because of the limited capability of the camera back, it was not possible to also record the month. To avoid becoming mixed up therefore, each month's batch of film from each ship had to be kept separate and labelled from the time it was unloaded on the ship, through processing and filing. The month and vessel name were added to the images during the scanning process.

Position:
The position of each vessel at the time the photo was taken may be retrieved from the archived surface met. data, which is recorded at 15 or 30-min periods. If spatial distribution of the clouds in earth co-ordinates is required, then the orientation of the camera relative to the ship is needed, and the ship's heading, preferably from 1-minute data. In the case of both Franklin and Wecoma, the axes of the camera frame were aligned with the ship and the bottom of the picture looks over the bow.

Frank Bradley (Frank.Bradley@enmech.csiro.au)