General concepts

Report

A homogeneous group of stations with the same kind of measures and management (for example: synop, metar, a specific kind of forecast…).

The type of report implicitly defines a priority of the measured value over other equivalent values. This can be used to select a “best value” from a specific set of coordinates, where for example, values measured by synoptic stations are preferred over values measured by a satellite, which in turn is preferred over a value computed by a forecast model (see Possible values for query modifiers).

Priorities associated to the report type can be customized when creating the database.

Station

Stations are uniquely identified by:

  • latitude.

  • longitude.

  • station identifier (if the station is mobile).

  • report

Station values

Each station entry can have zero or more values associated to it. They are just like measured variables, but lack date, time, level, and time range information. They can be used to store station attributes, like the height above sea level, or the center operating it.

Level or layer

The vertical coordinate of a value in DB-All.e is described using a level description or a layer description.

A level is defined univocally by a code table (leveltype1) and a numerical value (l1).

A layer is defined univocally by its two bounding levels (leveltype1, l1, leveltype2, l2).

See Level type values for a description of the level types and associated level values.

Time range

A value in DB-All.e is also defined by the time period to which the datum refers: it can be, for example, a value measured in a specific instant, or a cumulated or averaged value over an interval of time.

The time range is defined by a table code (pindicator) and two numerical values (p1 and p2). For their meaning, see Time range values.

Variable code (varcode)

A code from a local variation of BUFR/CREX Table B that describes the nature of the variable, such as what it measures and the units used for measuring. It is identified by a local B table descriptor (see Local B table codes).

Value

A measured value is a datum that can be expressed as a floating point (single or double precision), integer, character or byte, depending on what value it measures.

Every datum is univocally defined by a system of coordinates with 7 dimensions:

  1. A report type (see Report).

  2. The variable code (see Variable code (varcode)).

  3. The date and time of validity of the datum, be it observed, forecast or estimated.

  4. station information about what generated the value (also defining its x and y coordinates).

  5. The vertical coordinates in space, as a description of the level.

  6. The time range of the measurement.

Attributes

Values in DB-All.e are also associated to zero or more attributes. An attribute is a value that describes an aspect of a variable, like for example a confidence interval.

Attributes in DB-All.e consist on a value and a local B table descriptor, which describes the nature of the variable, such as what it represents and the units in which it is represented.

Attributes are uniquely identified by the variable they refer to and the B table descriptor of the attribute. As a consequence, you can only have one attribute per value with a specific B table descriptor. This means that, for example, a variable can have at most one confidence interval attribute.