Project

Global Energy Balance ; Radiation Budget; Climate Change; Solar radiation; Global Dimming; Surface Albedo

Lead
Lay summary
The genesis and evolution of Earth’s climate is largely regulated by the balance between inflow of solar energy (received from the Sun) and outflow of thermal energy (emitted by the Earth). Human interference with climate occurs first of all through a perturbation of this energy balance, as a result of anthropogenic modification of greenhouse gas and aerosol concentration. Changes in the global energy balance affect not only global warming, but also other aspects of climate change, such as the intensity of the water cycle, snow cover and glacier retreat, plant productivity and terrestrial carbon uptake. Despite the central importance of the global energy balance for the climate system and climate change, substantial uncertainties still exist in the quantification of its different components and their decadal variations. The long-term research goal of the investigators aims at an improved understanding of the mean state and the spatio-temporal variations of the global energy balance. While our knowledge on the energy exchange between Sun, Earth and space has recently been improved through new satellite programs, the distribution of radiative energy within the climate system, which cannot directly be measured by satellites, is still afflicted with large uncertainties. The present project aims at reducing the uncertainties in the absorption of solar radiation within the climate system, a crucial component of the global energy balance, through an optimal usage of the information contained in worldwide surface and satellite measurements. These investigations should allow for the best possible estimates on the disposition of solar radiation in the climate system. Such estimates are urgently needed for a better understanding and representation of the global energy balance in the framework of the 5th IPCC assessment report, and for the assessment and improvement of climate models.

Direct link to Lay Summary

Last update: 21.02.2013

Active participation

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The genesis and evolution of Earth’s climate is largely regulated by the Global Energy Balance. Anthropogenic climate change is, from a physical point of view, first of all a perturbation of the energy balance of the globe, through the modification of the atmospheric composition of greenhouse gases and aerosols. Changes in the global energy balance affect not only the thermal conditions on the planet, but also various other climate elements, such as the components of the hydrological cycle, snow cover and glaciers, plant productivity and terrestrial carbon uptake. Despite the central importance of the global energy balance for the climate system and climate change, substantial uncertainties still exist in the quantification of the different components of the energy balance and their decadal variations. The long term research goal of the applicant aims at an improved understanding of the mean state and the spatio-temporal variations of the different components of the energy balance of the globe. While our knowledge on the energy exchange between Sun, Earth and space has recently been improved through new satellite programs, the distribution of radiative energy within the climate system, which cannot directly be measured by satellites, is still afflicted with large uncertainties. The proposed PhD project aims at reducing the uncertainties in the absorption of solar radiation within the climate system, a crucial aspect of the global energy balance, through an optimal usage of the information contained in worldwide surface radiation measurements in combination with satellite products. This project makes extensive use of the comprehensive dataset of surface radiation measurements compiled by the applicants’ group in the Global Energy Balance Archive (GEBA), as well as of the Baseline Surface Radiation Network (BSRN). These data will be combined with recent satellite data (in particular CERES and MODIS) to quantify the top of the atmosphere fluxes and surface albedo. A number of long-standing and pressing issues with respect to surface radiation data are addressed in this project. This includes quality assessment of the stations collected in GEBA, homogenization of time series, the assessment of station representativeness, as well as best estimates of the surface albedo to infer absorbed solar fluxes from the measured downwelling fluxes. The aim of these investigations is to establish the best possible information contained in the surface radiation observations on the absorption of solar radiation at the Earth surface. In combination with collocated satellite data of top of atmosphere fluxes, this will provide a unique dataset of key reference (anchor) stations to investigate the disposition and variation of solar radiation in the climate system, as well as its representation in climate models and satellite-derived products. Such investigations are urgently needed for a better understanding and representation of the Global Energy Balance in the framework of the 5th IPCC assessment report.