The compilation of the Comprehensive Ocean-Atmosphere Data Set (COADS) as documented by Slutz et al. (1985) and Woodruff et al. (1987) has provided climate researchers with the most complete record of surface marine climate to date. The availability of this data set has contributed significantly to advancing our understanding of the atmosphere-ocean climate system. In addition to observational studies based on COADS, atmospheric and oceanic modelers have relied on this data set for boundary conditions in long-term integrations of atmospheric and oceanic circulation models.
One of the main contributions of the COADS project was to unify several historical data sets in a single, consistent format, and to subject the ship reports to the same quality control procedure. This homogenized data set is available in two forms: as monthly mean summaries in 2- by 2-degree boxes over the global oceans, and as raw individual observations. Due to the massive number of individual ship reports, the majority of researchers have used the monthly mean summaries.
In addition to the directly observed quantities (sea surface temperature, surface air temperature, etc.), COADS monthly mean summaries include a wealth of derived quantities such as moisture and pseudo oceanic fluxes, in which transfer coefficients have been ignored. In an attempt to extend and improve the oceanic fluxes in COADS, a collaborative project between the Department of Geosciences of the University of Wisconsin-Milwaukee (UWM) and the National Oceanographic Data Center/NOAA was initiated. The main goal of this project was to produce high resolution (1-degree by 1-degree), stability dependent heat and momentum fluxes, as well as evaporation, precipitation and radiational fluxes which were absent from the COADS monthly mean summaries. In addition to improved resolution and boundary layer parameterizations, a new scientific Beaufort equivalent scale was developed which reduces wind speed bias and artificial wind speed trends in the post World War II period.
Our revised monthly mean summaries (henceforth referred to as UWM/COADS monthly mean summaries) are available in the form of raw monthly means, standard deviations, and number of observations in 1 by 1-degree boxes over the global oceans, from 1945 to 1989. These raw data are made available for those users desiring to perform their own objective analysis. In addition, the monthly mean fields have been objectively analyzed with essentially the same successive correction scheme used by Levitus (1982). It is important to note that although the analyzed fields are given with a 1-degree grid spacing, only wavelengths greater than about 770 km remain due to the smoothing effects of the analysis. Climatological half-degree by half-degree analyses have also been produced; these results will be discussed elsewhere.
This atlas series presents objectively analyzed seasonal mean anomalies along with climatology, standard deviations, and observation density. This publication describes in detail the method of analysis, bias corrections, and parameterizations adopted. Also described is the format of the data in the UWM/COADS data set, along with information on the software used to read the data. The actual anomaly maps appear in subsequent volumes. The directly observed quantities are presented in Volume 2. Volume 3 deals with heat and momentum fluxes at the ocean surface. The buoyancy and fresh water fluxes are presented in Volume 4 and additional derived quantities are included in Volume 5.