acceptable data availability is. Twenty years ago a researcher looking for a data set began by searching in a library through card catalogs and periodical indexes, not uncommonly spending weeks finding relevant citations, locating the appropriate publication and its authors, requesting a copy of their data, and then waiting for the data to arrive by mail. Twenty years ago, a month was a reasonable and acceptable time for the entire data discovery and acquisition process. Today the expectation for that time frame has been compressed to less than a day.

Today’s data users want to go to their favorite search engine and type in a few keywords describing the data they are looking for. They then expect to immediately see a listing of all relevant sources with direct links to Web pages that describe the data and are capable of delivering it directly to users’ desktops with a simple click of their mouse. Finally, they expect the data to be in a format that is directly usable by whatever software package they happen to have. These are not unreasonable expectations for a potential data user, given today’s technologies. In fact, NOAA could make this specific data discovery and delivery scenario integral to its goal for users’ access to and use of its environmental satellite data. The achievement of the goal of near-real-time data availability is dependent on NOAA’s fulfillment of the four “ease” factors mentioned above and discussed in more detail below.

Data cannot be used unless it has been found and understood. The first step in making data widely available is to specify a metadata standard that will be applied to all data sets produced by a data supplier. The purposes of a metadata standard are to provide a common terminology and set of definitions for documentation of the digital data being described. The standard should establish the names and the structure of data elements to be used for these purposes as well as their definitions and information about the values that are to be provided for the data elements. (Metadata for federal geospatial data are required by Executive Order 12906, “Coordinating Geographic Data Acquisition and Access: The National Spatial Data Infrastructure,” which was signed in 1994 by President Clinton.) These metadata can then be used as a mechanism for distributing key words to agency Web sites and public search engines, thus enabling users to quickly and easily find and understand the data.

A user who has located data he believes will be useful will want to acquire the data as quickly as possible. If the data set is of a reasonable size, then the user should be able to download the entire set to a workstation via a widely accepted transfer protocol such as FTP or HTTP. If the data set is too large for such a transfer, then the user should be able to either view a compressed or degraded version of the data, or alternatively, download a subset of the data at its full resolution. The user can then order a CD or DVD of the data and have it delivered within a day or two.

Once a user has downloaded a data set to her desktop, it is imperative that the data be in a format that can be used easily—ideally, the most widely usable binary formats. When that is not possible, the format of the data should be fully docu-

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