Data structure

The data imported into the database have gradually evolved, and while at first only temporal data were imported, now spatial data are also becoming increasingly important.

Temporal data

A time series is defined as a set of random variables ordered with respect to time, and expresses the dynamics of a certain phenomenon over time.Historical series are studied both to interpret a phenomenon, identifying components of trend, cyclicality, seasonality and/or accidentality, and to predict its future trend.

Definitions

In order to analyze temporal data, these must be accompanied by other data describing the where, when and how (metadata). In this regard we need to give some definitions that they use in our OASI database.

Domain

The Domain is the environmental sector to which the measures refer, currently the following domains are present in the database:

  • Water

  • Air

  • Landslide

  • Light pollution

  • Weather

  • Non-ionizing radiation (NIR)

  • Noise

  • Soil

  • Traffic

Campaign

The Campaign is a conceptual grouping of measurement systems:

  • that are all part of a single measurement network

  • that are used in a given measurement campaign

A measurement system can be part of multiple campaigns.

Location

The Location is the generic place where the measuring station is located.

Warning

There is a tendency to think, incorrectly, that the location is the municipality where the measurement system resides while this could also be just a bounded area of a municipality. This happens because the system forces you to select the municipality where it resides.

Measurement system

The Measurement system, or station, is what comprises the set of measuring equipment, or devices. It is linked to a location and also defines the period during which the station was active.

Device

The Device is a physical instrument: a component of a station, a device or a sensor.

Parameter

The Parameter determines what a measurement, taken with an instrument, represents (e.g., temperature, ozone,…) and is associated with a specific measure unit and a specific type.

Parameter type

It’s a hierarchical ticipization used to determine the type of parameter. In oasi there are the following types:

  • Environmental: groups all parameters that have to do with or affect the environment

    • Physical: groups the parameters with physical properties (temperature, wind direction,…)

    • Chemical: groups the parameters with chemical properties (nitrogen dioxide, dissolved copper,…)

      • Micropollutant: groups the parameters of substances that, although present in small amounts, may have adverse effects on the environment and human health

    • Biological: groups the parameters that describe the condition or state of an ecosystem, organism, or biological process

    • Human activity: groups the parameters with properties, i.e. human-caused transformation of the natural environment

  • Control: groups the control parameters usually of a device (battery voltage, internal temperature,…)

  • Calibration: groups the parameters that are used to calibrate a device

Measure unit

The Measure unit is a predetermined quantity of a physical quantity, defined by parameter, which is used as a shared reference for measuring that quantity.

Measurement point

The Measurement Point is the exact place where a device, or instrument, acquires the measurement.

Resolution (or sampling)

The Resolution represents the time interval between two measurements (in minutes). In OASI, measurements are taken with the following resolutions:

  • < Daily: all samplings that occur several times a day (in minutes) or irregular samplings (0 minutes)

  • Daily: all samplings that occur daily (1440 minutes)

  • Monthly: all sampling that occur monthly (43200 minutes)

  • Yearly: all samplings that occur annually (525600 minutes)

Furthermore, for the daily, monthly and yearly cases, the following distinctions can also be made:

  • night: represent the samplings that occur during the night

  • day: represent the samplings that occur during the day

The hours considered for daytime are those from 06:00 to 21:59, and for nighttime those from 22:00 to 05:59.

Statistics or data aggregation

The data Statistics, namely the aggregations with integrated values, are done automatically by the OASI system starting from the raw data and with regular resolution. Minimum, maximum, and average statistics for daily, monthly, and annual resolutions are then created for each parameter. For some parameters there are more specific statistics such as:

  • sums for parameters such as precipitation, traffic volumes,…

  • vector average for wind direction,

  • energy average for some phonic parameters,

  • different hydrological sums,

  • air pollution indices,

  • …

It is possible, with the correct permissions, to calculate these statistics manually in the data analysis interface or in validation.

Organization

The Organization is the entity that owns and/or is responsible for a measurement system.

Spatial data

Spatial data refers to all those data related to objects in space, including, points, lines and polygons characterized by a geographic reference. The same are usually represented through a Geographic Information System (GIS).

Definitions

Geocatalog

The Geocatalog represents a collection of geographic data and information. The definition of geographic data and information is found in a series of ISO/TC 211 standards and is described as follows: an implicit or explicit association with a location relative to the Earth (a geographic location or geographic position).

Usually a geocatalog is composed of several geodata represented as layers.

In Palma the geocatalogs present are:

  • SPAAS: geocatalog of geodata managed at the Sezione dell’aria, dell’acqua e del Suolo (SPAAS),

  • geo.ti.ch: geocatalog of a subset of basic geodata related to the territory of the Repubblica e Canton Ticino <https://www4.ti.ch/dt/sg/sai/ugeo/temi/geoportale-ticino/tema/tema/>`_ that may be useful for environmental purposes,

  • IFDG: geocatalog of a sub-set of geodata from the Federal Spatial Data Infrastructure (FSDI <https://www.geo.admin.ch/en/federal-spatial-data-infrastructure-fsdi/>_) that may be useful for environmental purposes.

Geodata or layers

There are different types of geodata, including vector, raster, geographic databases, etc. These types of data are usually accessible through different standards, managed by the Open Geospatial Consortium (OGC), of which the most widely used are WMS, WFS and KML.

There are also some popular non-standard formats such as the shapefile (or ESRI shapefile) which was developed by ESRI and widely used in the business environment.

WMS

Web Map Service (WMS) refers to a technical specification defined by the OGC that dynamically produces spatially referenced data maps from geographic information. This international standard defines a “map” as a representation of geographic information by returning a digital image suitable for display on Web browsers.

WFS

Unlike WMS, the standard OGC Web Feature Service (WFS) interface returns vector data that must then be processed by a client. The returned data, which can be defined as the source code of a map, is usually defined as points, lines or polygons (in addition to metadata).

KML

Keyhole Markup Language (KML) is an XML-based language created to handle geospatial data in three dimensions (vector data) in Google Earth, Google Maps programs. KML became an international open standard recognized by OGC in 2008.

Shapefile

Shapefile, as mentioned earlier, is a popular vector format used in the business environment. A shapefile refers to a set of files with the extensions .shp, .dbf, .shx, and others, which have in common the name prefix that can alternately spatially describe points, polylines, or polygons.

Reference systems

All geodata need to be referenced to a particular coordinate system. The reference systems used in Switzerland are:

In addition, the WGS84 system compatible with Google Maps and other third-party maps is also used in the application.