Generic Structured Data Types and

Hydrologic Concepts

From Russ Rew (Unidata)• Collection of point data (unconnected x,y,z,t) Examples: earthquake data. • Collection of trajectories (connected x,y,z,t, ordered t) Examples: aircraft

data, drifting buoy. • Collection of profiler data (unconnected x,y,t, connected z) Examples:

satellite profiles. • Station collection of point (unconnected x,y,z, connected t) Examples:

metars. • Station collection of profilers (unconnected x,y; connected z, connected t)

Examples: profilers. • Trajectories of sounding (connected x,y,z,t, ordered z, ordered t) Examples:

ship soundings.

Those are in addition to • Gridded data on regular grids• Swaths, like grids except each row has its own associated time and other

metadata• Data on unstructured grids• Radial data, from weather radars, for example.

NOAAhttps://www.nosc.noaa.gov/dmc/swg/wiki/index.php?

title=Structural_Data_Types

Structural Data Class Descriptions and subclasses Examples and further explanation

Grids (and collections of grids) • rectilinear grids • curvilinear grids • finite element meshes outputs • “unstructured” grids (variable

numbers of vertices)

• finite difference model outputs • finite element model outputs • gridded (binned) data products • level 4 (gridded) satellite fields • spherical harmonic spectral

coefficients (1)

Moving-sensor multidimensional fields (and collections of same)

• swaths • radials

• satellite passes • HF radar • side-scan sonar • weather radar

Time series (and collections of time series (2)) • time-ordered sequence of records

(2) associated with a point in space or a more complex spatial feature.

• ocean moored measurements (3) • fish landings at a port • stream flow records • sun spot activity • climate data (surface atmospheric

stations) • paleo-records from cores, corals,

tree rings, … • computed climate indices such as

SOI

Profiles (and collections of profiles) • height or depth-ordered sequence

of records (1) at a fixed (or approximately fixed) point in time and position in lat/long

• atmospheric soundings • ocean casts • profiling floats • acoustic Doppler instruments

(structural overlap with time series)

Trajectories (and collections of trajectories) • time-ordered sequence of records

(2) along a path through space • underway ship measurements • aircraft track data • ocean surface drifters • ocean AUV measurements

Geospatial Framework Data (4) • lines

• polygonal regions • map annotations

• shorelines • fault lines • marine boundaries • continually operating reference

stations (CORS)

Point data (5) • scattered points • tsunami or seismic occurrences

• species sitings • geodetic control • geospatial data

Metadata “data about data” – context information needed for the interpretation of data

Like other data types metadata has distinct requirements for storage, access, archival and transport.

Metadata content is a major focus of discussions within all of the data types. Metadata as a “data type” refers specifically to its unique requirement and properties with respect to archival, access, and transport

Hydrologic Notions

• common hydrologic sampling features (beyond points):– Transects– Observations measured along a trajectory (aka the Ferrymon

case – perhaps there is a common name for such type of sampling?)

– Observations made along a vertical section (sequence of points at different vertical offsets)

– Observations made (or interpolated) on a grid (or cube ?) – Any other common type of sampling (e.g. along a stream?  - and

especially common samplings expected as model inputs)• integrated concepts that organize several types of

hydrologic measurements:– Stream, Channel, drainage network, tributary, junction, water

body, watershed, estuary (please add to these)

From Alexandria Gazetteer(DaveV)

• hydrographic featuresUsed for:– bodies of water – eddies – fluvial features – marine features – overfalls – upwellings – water bodies – waterholes – whirlpools Narrower Terms:– aquifers – bays – channels – drainage basins – estuaries – floodplains – gulfs – guts – ice masses – lakes – seas – streams – thermal features Related Terms:

http://www.alexandria.ucsb.edu/gazetteer/FeatureTypes/ver070302/00000130.htm

What we need• formal definition and model, construction methods,

retrieval methods, and priority of inclusion. • Consider transect

– if you are to store data measured along a transect, what are the transect characteristics you’d need to record?

– If you are to request data for a transect (either previously stored transect, or a transect you arbitrarily define over some point cloud and an interpolation procedure), what would you expect as a return?

– is transect a common enough and well defined concept to have it included in the schema, as opposed to a more general treatment of “sampling feature with a user-defined geometry”

– Consider getTransect(location1, location2, timePeriod), or getTransect (TransectID) - versus getValues (featuregeometry, relationship, timePeriod)?

• At the services API level? At the application level? As a way to describe grouping in database?