ReadMe
The information reported in this dataset was obtained through a series of research grants to Professor John T. Lehman of the University of Michigan from the U.S. National Science Foundation: OCE84-15970, OCE86-13880, OCE87-16187, OCE89-10999, OCE92-07945, and OCE-9508087. Additional research support was provided to J. T. Lehman by Michigan Sea Grant: MICHU-SG-92-302-R/ES-5.
The main directory contains general descriptions of the dataset including the master list of sampling stations (StationList_Master) that contains the following station identifiers: Year, Date, Lake, Latitude (degrees and decimal minutes N), Longitude (degrees and decimal minutes W), Latitude in decimal degrees (decLat), Longitude in decimal degrees (decLong), and maximum station depth in meters (Zmax).
Data are organized in four zipped folders: Chemistry, CTD profile data, Plankton, and Ship Logs as follows:
Chemistry
This folder contains one RTF document (Chemical_Methods) that describes the analytical protocols for water chemistry data and a second Word document (Key to File Chemistry85-97_Master) that explains the abbreviations and measurement units used in the chemistry dataset. The water chemistry data are contained in the Excel file Chemistry85-97_Master.
Chemistry85-97_Master contains data tabs as follows: Stations lists all stations for which data are available using the same station identifiers as StationList_Master. Data themselves are organized in tabs by year according to Cruise, Date, Time (24-hour format), Station, Latitude, Longitude, depth of sample collection (m), and the various analytes.  
CTD profile data
This folder contains a master list (CTDcatalog_Master) of the CTD casts by year, filename, lake, date and time, latitude, longitude, station depth, and type of cast (vertical profile). It also contains an RTF document describing data processing steps taken with the data (CTD Data Processing Log) as well as an Excel file listing water temperatures (C) measured with an electronic bathythermograph (EBT) organized by Lake, Station, Date and Time for the years 1985, 1986, 1987, and 1989.
The CTD data themselves are in six subfolders: Erie, Huron, Michigan, Saginaw Bay, St. Clair, and Superior. Each lake folder contains two subfolders named “Processed files” and “Raw data.” The data are organized in subfolders by year. Processed data are in ASCII format. Raw data are in Seabird binary file format.
Plankton
This folder contains a master list (PlanktonLog_Master) of zooplankton samples collected by submersible pump (1985 and 1986 only) or Puget Sound vertical closing net (all years). Descriptors include sample number, sample type, Date, Time, station ID, latitude and longitude (both in degrees and decimal minutes and in decimal degrees N and W respectively), upper and lower depths sampled in meters, net mesh in micrometers, the split fraction used for counting, and any incidental remarks. The folder also contains three Excel data files. Mysis-Counts_Master and ZoopCountSummary_Master  contain abundance data for Mysis relicta and other crustacean zooplankton, respectively. The RTF document “Key to Files Mysis-Counts_Master and ZoopCountSummary_Master” identifies the data descriptors and taxon abbreviations used in these two data files. The third Excel data file is ZoopSize85-86, which contains length-frequency data for individual taxa measured by ocular micrometer from 1985 to 1990. The RTF document “Key to File ZoopSize85-90” identifies the data descriptors and taxon abbreviations used in that third data file. 
 Ship Logs
This folder contains pdf copies of ship logs handwritten by the Ship Master. The files are labelled with the format YEAR_MMDD for single day cruises and YEAR_MMDD-MMDD for multiple day cruises.