Development and Application of Energy Balance Climatology

Abstract

Energy balance processes play a vital role in characterizing the climate and in causing climate change. The traditional method for energy balance studies tended strongly toward computational methods, sacrificing to some extent the consideration of the observed values. High-quality observations of energy fluxes were also lacking, and their data were often not organized for scientific purposes. To overcome these problems, the author initiated two projects to obtain and organize instrumentally measured energy balance components. The Global Energy Balance Archive (GEBA, World Climate Programme-Water A7) extracted all observed fluxes based on the information available in publications and existing data sources, such as national meteorological services. GEBA also maintains records of the oldest measured fluxes, such as solar global radiation of Stockholm going back to 1922. A specialty of GEBA is the inclusion of nonradiative fluxes, such as sensible heat and latent heat fluxes. As an example, the longest continuous data on evapotranspiration are those observed at Rietholzbach over the 45-year period from 1977 to 2023. The main problem of the GEBA data is the uncertainty of their accuracy, as the available data were all accepted with a rather broad error screening process. The accepted data were obtained by different organizations for different purposes. The Baseline Surface Radiation Network (BSRN, WCRP/DEWEX project; GCOS network), on the other hand, is designed to monitor radiative fluxes with the highest accuracy currently possible. The instruments, observation methods, and calibration procedures are standardized. The calibration of the instruments is traceable to World Standard instruments at the World Radiation Centre in Davos, Switzerland. The project began in 1992 and continues to the present. The databank of BSRN, however, has only radiative components. These data sources contributed greatly to improving computational processes of the energy balance components in climate models. The work based on these data ultimately led to discoveries of missing absorption, global dimming and brightening of solar radiation, and missing emission of the atmospheric downwelling radiation. The errors corrected with observed irradiances are on the order of 20 W m⁻². The weight of the flux errors of this order is much more substantial in comparison with climatic change factors such as the radiative forcing held by all anthropogenic greenhouse gases, which is estimated at 2.3 W m⁻². The BSRN stations continue to play a role as radiation monitors. Recently discovered global increases in atmospheric counterradiation have a large acceleration, which necessitates the correction of the current radiative forcing. Long-term monitoring of radiative fluxes contributes to climate prediction by presenting changing irradiances that help steer the course of prediction toward the correct target.