Talk:Geocode

Geocodes are used by PANGAEA to geo-reference the origin of data values in space and time on Earth. In PANGAEA’s relational data, each value is geo-referenced, using diverse Geocodes. They define and indicate in which environment the samples or measurements were taken.

Spatial Geocodes (x,y,z)
Spatial Geocodes are used to define sampling points, sensor locations, etc. Most important and mandatory Geocodes for georeferenced data are the geographical coordinates.

LATITUDE and LONGITUDE (x,y)
LATITUDE and LONGITUDE are given in decimal degree (positive for North, negative for South, WGS84). They are specified in each Event and can additionally expand the data tables and georeference individual samples more precisely.
 * For data sets from a single location (= one point on Earth, sediment cores, ice core, outcrop, vertically used net, single CTD, etc.) the coordinated latitude and longitude are defined through the Event. Example: https://doi.org/10.1594/PANGAEA.953292.
 * For data sets from many locations (several points on Earth, surface sampling, profile series, etc.) or horizontal profiles (horizontal nets, acoustic profiles etc.) latitude and longitude are given in the data table. Example for many locations: https://doi.org/10.1594/PANGAEA.953880, example for horizontal profiles: https://doi.org/10.1594/PANGAEA.953917.

Third spatial dimension (Depth/Height) (z)
There are several options for specifying the third spatial dimension (Depth/Height) (z). These Geocodes also specify the sample milieu: lithosphere, hydrosphere, cryosphere, atmosphere, biosphere

DEPTH
Depending on the origin of the data:
 * DEPTH, sediment/rock [m] for geological, geochemistry, biogeochemisty, paleontological, geophysical measurements and samples. Describing the specific sampling depth in the sediment core, example: https://doi.org/10.1594/PANGAEA.945578.
 * DEPTH, sediment, experiment [m] for georeferenced experiments in sediment environments, i.e., lander experiments. Experiments in the field must be distinguished from real field measurements. They do not reflect reality, but manipulated values. Therefore, we use experiments geocodes, example: https://doi.org/10.1594/PANGAEA.896026.
 * DEPTH, soil [m] for pedological studies. Describing the specific sampling depth in a pedologic profile or core, example https://doi.org/10.1594/PANGAEA.943118.
 * DEPTH, water [m] for all studies in water columns, e.g., CTD profiles, moorings, biological sampling, hydrochemistry, etc. This GEOCODE describes the water depth in which the measurement or sample was collected, example https://doi.org/10.1594/PANGAEA.952363.
 * DEPTH, water, experiment [m] for georeferenced experiments in the water column, e.g., mesocosm data. Experiments in the field must be distinguished from real field measurements. They do not reflect reality, but manipulated values. Therefore, we use experiments geocodes, example: https://doi.org/10.1594/PANGAEA.933089.
 * DEPTH, ice/snow [m] for sampling and measurements in shelf- and sea-ice. Example: https://doi.org/10.1594/PANGAEA.945857.

HEIGHT
Depending on the milieu and position on Earth:
 * ELEVATION [m a.s.l.] Height/bottom depth relative to sea level. Positive above mean sea level, negative below mean sea level – i.e., for specifying a location of a sediment core site at the bottom of the Mariana Trench = -10984 m, or the position of an instrument on the Mount Everest = 8848 m. Specified in each event and can additionally expand the data tables and georeferences the individual samples more precisely. Below sea level, ELEVATION is identical to negative bottom depth/bathymetric depth. Can be used for samples taken on the Earth surface, for example, for geological rock sampling along a mountain climb. Example: https://doi.org/10.1594/PANGAEA.918658.
 * ALTITUDE [m] for measurements in height above sea level, i.e. in the air. Example: https://doi.org/10.1594/PANGAEA.944409.
 * HEIGHT above ground [m] for measurements in meter above ground (not above sea level). Used whenever we specify the height above the ground, both on land and above the ocean floor. The elevation to this sample point is defined in the event label, example: https://doi.org/10.1594/PANGAEA.943231.

Relative spatial Geocodes
The following geocodes do not give an absolute position on Earth. They are used to position the samples/measurements relative to a defined location (Event). This is always the case when a distance indication in an object or transect is decisive, and not the absolute orientation on the Earth.
 * DISTANCE [cm] is a relative measurement in an object. It gives the distance from a measurement start point and can be used for corals, trees, shells, nodules etc. Please keep in mind that the object position on Earth must be defined in the Event label. Example: https://doi.org/10.1594/PANGAEA.945784.
 * POINT DISTANCE from start [m] is used for measurements along a horizontal transect. It gives the relative distance from a start point for example on sea ice, shelf ice, vegetation observation. The Start point’s position on Earth is defined via the Event label. Example: https://doi.org/10.1594/PANGAEA.951583.
 * SECTION, height [m] gives the relative height of a vertical profile. This Geocode is often used for geological data and gives the height from the bottom of an outcrop, or the height related to a specific geological layer. The outcrop’s position on Earth is defined by the Event label. Example: https://doi.org/10.1594/PANGAEA.943591.
 * ORDINAL NUMBER may be used if samples should just be kept in order. It can be used as a single geocode or in combination with other geocodes, example https://doi.org/10.1594/PANGAEA.949186.

Time Geocodes
In addition to the vertical Geocodes, a time coding of the data should be used whenever possible. These Geocodes describe either the time of sampling or the geological age of a sample.
 * AGE [kyr BP] is the Geocode for geological samples. All geologic ages in PANGAEA are given in ka to have an overall timeline of geology. In addition, the ages can also be given in millions year [Ma] or years [a] in Greogorian calender year [a AD/CE] with AD = Anno Domini, CE = Common Era. Geologic studies are far more comparable by age dating than by sediment depth. Therefore, if possible, all geological data should include ages. Examples: https://doi.org/10.1594/PANGAEA.950681 or https://doi.org/10.1594/PANGAEA.944532.
 * DATE/TIME Sample time is essential for biological data and time series. This also applies to experimental data. Date/time format follows the ISO-standard 8601 yyyy-MM-ddThh:mm:ss. Example: https://doi.org/10.1594/PANGAEA.953917. Different formats can be displayed in the data set, depending on the accuracy of the date/time specification, see below.