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Coherent Area Study, 1963-1971
The Coherent Area Study (CAS) was an interdisciplinary study of the biology, chemistry, geology, meteorology, and physical limnology of Lake Michigan. Funded by the U.S. Public Health Service, CAS aimed at gathering scientific information on the behavior of large lakes, particularly the process of and factors leading to eutrophication. The study was conducted in two phases, 1963-1967 and 1967-1971, under the direction of John Ayers, professor of oceanography and GLRD research scientist. Data for the study was gathered at monitoring stations and from research vessel cruises. Records in this series include field and laboratory data, analysis and reports, and a variety of research vessel logs.
The arrangement of the CAS series begins with a series of background and summary files. These are followed by series for each of the major areas of scientific study: water temperature, biological, chemical, climatological, meteorological, and wind current studies. There are small series of audiotapes and photographs and films.
Arranged in a separate series are two series of ship's logs which relate in part to the Comprehensive Area Study. The ship's logs series and chief scientist's logs series, described below, cover research vessel cruises for CAS as well as earlier and later studies. Researchers should note the interrelationships among these records, particularly the various field data logs and the ship's logs. It may be necessary to consult the ship's logs to determine precisely where in the lake and under what conditions readings or samples were taken.
Background and Summary Files
The Background and Summary Files subseries includes the grant renewal application, a summary report on the first phase of the study, bibliographies, and several historical data files The Grant Renewal Application, 1966, provides summary information on the preliminary findings of the 1963-1967 phase of the project and describes the studies to be carried out in the second phase. The draft Supplemental Progress Report, Oct. 1966 provides an outline of CAS work completed to date.
Bibliographies consists of abstracts of previous publications and research on Lake Michigan. Historical Data is time-series data on water temperature, wind, and meteorological conditions from cities around Lake Michigan. Some series were apparently compiled by Ayers, others were provided by local agents such as city water filtration plants. It was part of a "weather library" created by Ayers and GLRD. The Summaries of Data Collecting Logs of Research Vessel Cruises provide summaries of the type, extent, and location for data collected on GLRD research vessel cruises, 1962-1967.
Water Temperature Studies
The Water Temperature Studies subseries consists of several files relating to bathythermograph recordings and other water temperature logs. A bathythermograph is a device which is lowered into the lake to record changes in water temperature as a function of depth. The instrument etches a line on a coated glass slide. The slide is then projected and photographed against a graph for interpretation.
Files include: Station Locations, a list of fixed stations from which recordings were made; Bathythermograph Logs, a record of the date, time, location, and other information for observations made from research vessels; Bathythermograph Glass Slides and Bathythermograph Photographs of some slides. The bathythermograph logs, slides, and photographs are arranged by year and research vessel. Other logs record water temperatures at fixed stations in Lake Michigan and Lake Huron. The Airborne Radiant Thermograph file is data from an experimental system using an ASWEPS (Anti-submarine Warfare Environmental Predictions Services) Oceanographic research plane to measure lake surface water temperature.