Articles | Volume 10, issue 8
Atmos. Meas. Tech., 10, 3057–3071, 2017
Atmos. Meas. Tech., 10, 3057–3071, 2017

Research article 23 Aug 2017

Research article | 23 Aug 2017

Revising shortwave and longwave radiation archives in view of possible revisions of the WSG and WISG reference scales: methods and implications

Stephan Nyeki1, Stefan Wacker2, Julian Gröbner1, Wolfgang Finsterle1, and Martin Wild3 Stephan Nyeki et al.
  • 1Physikalisch-Meteorologisches Observatorium Davos and World Radiation Centre (PMOD/WRC), Davos, Switzerland
  • 2Deutscher Wetterdienst, Meteorologisches Observatorium Lindenberg/Richard-Aßmann-Observatorium, Lindenberg, Germany
  • 3IACETHZ, Zurich, Switzerland

Abstract. A large number of radiometers are traceable to the World Standard Group (WSG) for shortwave radiation and the interim World Infrared Standard Group (WISG) for longwave radiation, hosted by the Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre (PMOD/WRC, Davos, Switzerland). The WSG and WISG have recently been found to over- and underestimate radiation values, respectively (Fehlmann et al., 2012; Gröbner et al., 2014), although research is still ongoing. In view of a possible revision of the reference scales of both standard groups, this study discusses the methods involved and the implications on existing archives of radiation time series, such as the Baseline Surface Radiation Network (BSRN). Based on PMOD/WRC calibration archives and BSRN data archives, the downward longwave radiation (DLR) time series over the 2006–2015 period were analysed at four stations (polar and mid-latitude locations). DLR was found to increase by up to 3.5 and 5.4 W m−2 for all-sky and clear-sky conditions, respectively, after applying a WISG reference scale correction and a minor correction for the dependence of pyrgeometer sensitivity on atmospheric integrated water vapour content. Similar increases in DLR may be expected at other BSRN stations. Based on our analysis, a number of recommendations are made for future studies.

Short summary
A large number of radiometers used to measure solar and terrestrial broadband radiation are traceable to World Standard Groups at PMOD/WRC in Davos, Switzerland. A small correction of each group may be required in the future, and this study examines the methods and implications of this on data sets collected at four remote baseline stations since the 1990s. The goal is to develop a better estimate of the solar and terrestrial radiation budget at the Earth's surface.