CryoNet Station and Cluster Types

The GCW surface observation network is comprised of a core component, called CryoNet, and contributing stations that are not part of CryoNet. The GCW network builds on existing cryosphere observing programmes and promotes the addition of standardized cryospheric observations to existing facilities in order to create more robust environmental observatories. The basic component of the GCW network is the station. A station measures one or more components of the cryosphere and one or more variables of each component, for example depth and density of the component snow. CryoNet Stations must meet a minimum set of requirements, which includes providing ancillary meteorological measurements. Potential attributes of CryoNet stations are given below. All stations will be either Primary or Reference, and may have one or more additional attributes.

• Primary - Have a target (intent) of long-term operation and have at least a 4-year initial commitment.
• Reference - Have a long-term operational commitment and long-term (more than 10 years) data records.
• Cal/val - In addition, the station is being used for calibration and/or validation of satellite products and/or (earth system) models, or it has been used for such purposes in the past and it still provides the needed facilities.
• Research - In addition, the station has a broader research focus related to the cryosphere.

A CryoNet Cluster¹ generally encompasses an area greater than a conventional observing station and is comprised of two or more active GCW stations with varying capabilities that are operated as a coordinated unit. At least one station has to be a CryoNet station. A cluster may encompass several micro-climatological regions or extend over larger altitudinal gradients. Thus, further ancillary meteorological stations are part of a cluster. Different partners may operate the stations, but they are co-ordinated through one agency or institute. Each CryoNet cluster has to provide a concept describing the research approach and the cluster management (e.g. cooperation between different partners). CryoNet clusters must also meet a certain requirements.

Typically, clusters have a broader research focus related to the cryosphere compared to stations. Whereas simple clusters investigate the cryosphere only, integrated clusters aim to provide a better understanding of the cryosphere and/or its linkages to other components of the earth system, for example, the atmosphere, the hydrosphere, the biosphere, the oceans, soil, vegetation, etc. Potential attributes of CryoNet clusters are:

• Basic - Monitor single or multiple components of the cryosphere.
• Integrated - Monitor at least two components of cryosphere or at least one cryosphere component and one other component of the earth system. Integrated clusters are particularly important for the study of feedbacks and complex interactions between these components.

A GCW contributing station is required to measure at least one variable of at least one cryosphere component (e.g. snow, permafrost, sea ice, etc.). Contributing stations are those that provide useful measurements of the cryosphere but do not fulfill CryoNet minimum requirements, or in some other way do not provide the quality and/or consistency of data required by CryoNet stations; for example, where data records may be short or with large gaps. These stations may be in remote, hard to access regions where cryospheric observations are scarce or in regions where they complement other cryospheric measurements. Mobile platforms such as ships, drifting stations and buoys may also be contributing stations. Contributing stations may have this attribute:

• Reference - Have a long-term operational commitment and/or long-term (more than 10 years) data records.

Synoptic/climate stations of the NMHSs measuring cryospheric variables to WMO standards, and providing their metadata and data via WIS and WIGOS, could fulfill the necessary requirements in order to contribute to GCW and to be accepted as stations in the GCW surface network.

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¹CryoNet "Clusters" were called "Sites" until January 2018. The terminology change was made to avoid confusion, as the word "site" is used interchangeably with "station" in some countries.