To identify a particular data set (sometimes referred to as a data stream) you need to specify the following: - a Domain - a Station - a stream or data Name - a Method - a SensorCode - an Aspect
Domain is a broad collection method or data discipline. Some volcano data have the envirosensor domain, and some the manualcollect domain.
The observation site, the feature at the volcano where the observations are collected, is referred to as the Station. Each is a unique five character code. Stations can be found using the Tilde API's DataSummary endpoint, or through Tilde's Data Discovery GUI.
For volcano observations, the first part of the Station code is two upper case letters which represents the volcano where the site is situated. For the manualcollect domain, the second part of the Station code is a three-digit number, with leading zeros. For envirosensor domain data, the same pattern is used, except when the data logger records data from more than one nearby, but differently named, features. In that case, the three-digit number is replaced by three upper case letters that reflect the location of the data logger. Examples are provided below.
| Volcano | Two Letter Code |
|---|---|
| Auckland | AU |
| Mayor Island | MY |
| Ngauruhoe | NA |
| Okataina | OT |
| Raoul Island | RL |
| Reporoa | RP |
| Rotorua | RR |
| Ruapehu | RU |
| Taranaki | TR |
| Taupō | TP |
| Tongariro | TG |
| Whakaari/White Island | WI |
| Whale Island | WH |
At Te Wai ā-moe (Ruapehu crater lake), where GeoNet collects several data streams, the Station code is RU001.
To indicate Ruapehu as a whole volcano, not a specific feature, the numeric part of the Station code is 000. For example, dealing with volcanic gases at Ruapehu, which can represent the aggregated output from all vents and features at the volcano, the Station code is RU000.
A data logger at Upper Emerald Lake on Tongariro collects data from two nearby features TO060 (Tongariro Upper Emerald Lake) and a nearby fumarole. The Station name used is TOUEM (Tongariro Upper Emerald).
For convenience, sites at a particular volcano that are used to collect the same kind of observation are assigned similar Station codes, with the numeric part of the Station code drawn from a consecutive series of numbers. For example, there are 22 sites on the shore of Lake Taupō used for periodic measurements of vertical ground deformation, and their Station codes range from TP001 to TP022. At Tongariro, Station codes for springs, pools and streams where water sampes are collected range from TO050 to TO063.
Name specifies the name of the data stream or series. It consists of two parts, the kind of feature at which the observations are made, followed by a - hyphen, and then the type of observation. There are no spaces in Name.
Examples of feature include air, fumarole, ground, lake, plume, and spring.
Examples of the type observation include CO2-gasflux, Fe-conc, rainfall, temperature, and vertical-displacement. Easily described observation types use one word, less easily described use two (or even three) words separated by a - hyphen.
Examples of a complete Name include plume-CO2-gasflux, ground-vertical-deformation, and spring-temperature.
Method specifies how data are collected. Data collection methods have advantages and disadvantages and it is important for many data users to understand what method was used. For the manualcollect domain this might be the measurement device used, e.g. thermocouple or the technique used, e.g. contouring. For the envirosensor domain, Method is typically either snapshot for an observation at a particular instant, or max or min for an obseravtion made over a time interval.
For the envirosensor domain, where there are likely to be several different sensors attached to a single data logger, SensorCode gives each sensor a number, 01, 02, 03, etc.
For the manualcollect domain, SensorCode is used to identify distinct parts of a feature. For example, at Te Wai ā-moe (Ruapehu crater lake) there are several sub-features where observations are commonly made, the lake's outlet, a central vent in the lake, and a northern vent in the lake. These are indicated by a SensorCode MC01, MC03, and MC04, respectively. SensorCode used with the manualcollect domain consists of MC followed by two digits, in contrast to envirosensor and other Tilde data domains where SensorCode is just two digits. This is because of the slightly different meaning it has with manualcollect.
Aspect is used to further distinguish between data sets if all the previous categories are not sufficient. An example might be where a single temperature sensor takes observations at several different depths below the ground surface. In this case, the Aspect might be 10-cm, 20-cm, etc.
In most cases, the manualcollect domain does not need to use Aspect so it is set to nil.
Tilde's data discovery GUI is an easy to use interface to Tilde through your web browser. As well as providing information about data in each Domain and links to additional information, it allows you to select, view, and download data. You need to start by selecting a data Domain and then you can select Name and Station, followed by Method, SensorCode, and Aspect, which are optional and whose value depends on the data set you are looking at. AFter selecting a Date Period, either the last few days (or hours) or a specific date range, you can submit your request and will be shown a graph of the data returned (if any). The graph is interactive and you can save a static image from the graph to your device. There are also options for data aggregation, e.g. providing a daily mean value rather than the raw data. The URL used for your query request is also provided so you can bookmark that or use it in your own applications.
THe data discovery GUI is the recommended way to start working with Tilde as you don't need to understand how to create data queries. But if you want to do that, you can interact with the API directly.
To retrieve data, the data API endoint must be used.
This is the minimum that can be specified to retrieve observation data from Tilde; what kind of data, from where, and when.
Manually collected (Domain = manualcollect) plume SO2 gas flux (Name = plume-SO2-flux) data from Ruapehu (Station = RU000) from 2020 to end-April 2024.
https://tilde.geonet.org.nz/v3/data/manualcollect/RU000/plume-SO2-gasflux/-/-/-/2020-01-01/2024-04-30
The issue with the results returned by this query is that we get data returned that have been collected using multiple different methods, as we didn't specify Method. But we can distinguish the different methods as it is provided in the output. If with want data from only one collection method, we need to include Method in our query.
Manually collected (Domain = manualcollect) plume SO2 gas flux (Name = plume-SO2-flux) data measured using the contouring method (Method = contouring) from Ruapehu (Station = RU000) from 2020 to end-April 2024.
https://tilde.geonet.org.nz/v3/data/manualcollect/RU000/plume-SO2-gasflux/-/contouring/-/2020-01-01/2024-04-30