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TSTool Documentation This documentation can be printed double -sided and is best viewed as PDF to use the navigable table of contents and bookmarks. 2.1 Time Series Objects and Identifiers TSTool considers time series as objects that are queried, manipulated, viewed, and output. A time series is defined as a series of date /time versus data pairs. Data generally consist of floating point values; however, time series may contain other data (e.g., data quality flags). TSTool treats time series as either regular interval (equal spacing of date /time) or irregular interval (e.g., infrequent measurements, sometimes referred to as observations). Regular time series lend themselves to simpler storage and faster processing because date /time information only needs to be stored for the endpoints and processing is less complicated. TSTool defines each time series as having an interval base and multiplier (e.g., 1Month, 2 4Hour). In many cases, the multiplier is 1 and is not shown in output (e.g., Month rather than 1Month is shown). In addition to a period of record, interval, and data values, time series have attributes, or metadata, that include: • Units (e.g., CFS) • Data type (e.g., Streamflow) • Data limits (the maximum, minimum, etc.) • Description (generally a station or structure name) • Missing data value (used internally to mark missing data and trigger data filling, often — 9 9 9 or in some cases NaN [Not a Number]) • Comments (often station comments, if available) • Genesis history (a list of comments about how the time series was created and manipulated) To manage time series, TSTool associates each time series with an identifier that uses the notation: Location. Source. Type. Interval. Scenario [Seq]— InputType— InputName Location.Source. Type. Interval .Scenario[Seq]— DataStoreName The first five parts (Location. Source. Type. Interval. Scenario) are used to identify time series, with further explanation below: • Location — typically a physical location identifier, such as a station, basin, or sensor identifier. • Source — a data provider identifier, usually a government or system identifier (e.g., USGS, NWS), necessary because sometimes the provider for data changes for a location. • Type — the data type, typically specific to the data (e.g., Streamf low, Precip) — TSTool does not try to institute global data type definitions). • Interval — the data interval, indicating the time between data values (e.g., 6Hour, Day, Irregular). • Scenario — an optional item that indicates a scenario (e.g., Hist, Filled, Max, Critical). • Seq — an optional item used in cases where multiple time series traces may be available, with all other identifier information being equal (e.g., for simulations where multiple versions of input are used or for cases when a historical time series is cut into annual traces, collectively known as Introduction - 2 22