Station requirements and categorization#

This sections defines the minimum requirements for a station to be included in in the list of high-quality solar radiation monitoring stations. The most restricting criteria is that all stations are required to measure at least two of the three irradiance components, such that the last component can be calculated.

Station categorization#

The stations are subdivided into two different categories: Tier 1 and Tier 2 stations.

Tier 1 stations#

Tier 1 stations are defined as those that meet all of the following requirements:

  • measurement of direct normal irradiance (DNI) with a Class A thermopile pyrheliometer mounted on a solar tracker

  • measurement of diffuse horizontal irradiance (DHI) with a Spectrally Flat Class A thermopile pyranometer shaded by a shading ball

  • measurement of global horizontal irradiance (GHI) with a Spectrally Flat Class A thermopile pyranometer

Seperate measurement of GHI is required for Tier 1 stations as most quality control procedures relies on comparing the measured and calculated GHI (closure equation). The stations in the BSRN network are examples of Tier 1 stations.

Tier 2 stations#

Tier 2 stations are defined as those that do not meet the Tier 1 requirements but meet one of the following specifications:

  • Meets two of the three requirements of Tier 1 stations

  • Measures GHI and DHI using a rotating shading band pyranometer

Non-qualifying stations#

Stations that measure DHI using a manually ajusted shadow band are not considered, as such measurements are notoriously unreliable due to the shadow band having to be adjusted every few days.

Station metadata#

The central part of the catalog is the list of stations and their metadata, which as a minimum should include:

  • Latitude, longitude, and elevation (according to ISO format)

  • Years of operation

  • City and Country

  • Station name

  • Station abbreviation

  • Station network (e.g., BSRN, SURFRAD)

  • Link to the station or network website (multiple links?)

Time-period#

The station time-period is useful for a number of reasons, e.g., in identifying which stations are still active and how long of a historical record of data is available. The time-period should identify for which years data is available. For example, for an active station from 2013 which does not have data for 2014 and 2017, the time-period would be: 2013&2015-2016&2018-. For BSRN stations the time period should be identified based on the available data, which can be seen here.