Is it possible to estimate aerosol optical depth from historic colour paintings?

The idea of estimating stratospheric aerosol optical thickness from the twilight colours in historic paintings – particularly under conditions of volcanically enhanced stratospheric aerosol loading – is very tantalizing because it would provide information on the stratospheric aerosol loading over a period of several centuries. This idea has in fact been applied in a few studies in order to provide quantitative estimates of the aerosol optical depth after some of the major volcanic eruptions that occurred during the past 500 years. In this study we critically review this approach and come to the conclusion that the uncertainties in the estimated aerosol optical depths are so large that the values have to be considered questionable. We show that several auxiliary parameters – which are typically poorly known for historic eruptions – can have a similar effect on the red–green colour ratio as a change in optical depth typically associated with eruptions such as, for example, Tambora in 1815 or Krakatoa in 1883. Among the effects considered here, uncertainties in the aerosol particle size distribution have the largest impact on the colour ratios and hence the aerosol optical depth estimate. For solar zenith angles exceeding 80∘, uncertainties in the stratospheric ozone amount can also have a significant impact on the colour ratios. In addition, for solar zenith angles exceeding 90∘ the colour ratios exhibit a dramatic dependence on solar zenith angle, rendering the estimation of aerosol optical depth highly challenging. A quantitative determination of the aerosol optical depth may be possible for individual paintings for which all relevant parameters are sufficiently well constrained in order to reduce the related errors.</p

A novel conceptual model facilitating the derivation of agent-based models for analyzing socio-technical optimality gaps in the energy domain

Optimization and simulation models are fit to work on a multitude of technical, economic, and techno-economic questions. However, they are by now not able to satisfactorily include societal aspects like acceptance, spatial implications and legal frameworks. In order to advance scope and explanatory power of simulation models, collaboration in interdisciplinary research teams is needed. Yet the exchange in such teams and its coordination can prove challenging. Furthermore, disciplinary approaches and methods for simulation and optimization might not be familiar to all participants. To this end, a new conceptual model is introduced. The conceptual model employs few basic elements and concepts for describing and explaining arbitrary societal and technical relationships. Most notably, the conceptual model is general in its design, so contributions to the problem formulation and design components can be made by all team members regardless of their discipline. The procedure is based on common agent-based concepts without using their terminology. Consequently, an exchange among all team members becomes possible without them necessarily being proficient in agent-based modeling. A reduced presentation of workshop results exemplifies the use of novel elements for deriving an emergent agent-based simulation

Die Energiewende regional gestalten : auf dem Weg zu einer Energiewende-Roadmap im Ruhrgebiet

Diese Broschüre ist ein Produkt des Rahmenprogramms zur Umsetzung der Energiewende in den Kommunen des Ruhrgebiets: Die Auf­gabe des Projektes bestand darin auszuloten, in welcher Weise Kommunen ihre Handlungskapazitäten zur Umsetzung der Energiewende in der Region bewahren beziehungsweise perspektivisch erweitern können. Das Rahmenprogramm steuerte in seiner dreijährigen Projektlaufzeit (2013-2016) einen Beitrag zur Analyse der Handlungsfähigkeit von Kommunen im Ruhrgebiet zur Umsetzung der Energiewende bei und systematisierte bisherige Handlungsansätze in der Region. Es setzte an bestehenden Rahmenbedingungen an und versuchte, in Zusammenarbeit mit regionalen Akteurinnen und Akteuren künftige Handlungsansätze für eine langfristig angelegte Umsetzung der Energiewende in der Region zu identifizieren. Das vorliegende Dokument führt Ergebnisse des Pro­jektes zusammen und formuliert strategische Hinweise für die weitere Umsetzung der Energiewende im Ruhrgebiet