Towards a more complete assessment of the impact of solar variability on the Earth’s climate

• Research unit: COST
• Project number: C11.0135

Key words (English)

Solar irradiance; modeling; climate; solar atmosphere; Sun-Earth connection

Research programs (English)

COST-Action ES1005 - Towards a more complete assessment of the impact of solar variability on the Earth’s climate

Short description (English)

Solar irradiance is a key parameter for climate modeling and its UV component is affecting directly space weather. During the last decade the role of spectral and total irradiance has gained increased attention and presently, many groups are worldwide highly active in measuring and modeling solar irradiance. To contribute to the action goal to 'more completely assess the variability of solar irradiance', we focus on the analysis of solar irradiance data from the operating European missions PROBA-2 (launched on November 2, 2009) and PICARD (launched on June 15, 2010). The PMOD/WRC has built the hardware of the radiometer experiments on both missions: LYRA on PROBA-2 and PREMOS for PICARD. An essential part of our contribution to the COST action (as well as to the FP7 project eHEROES) is to deliver operationally calibrated PREMOS spectral irradiance data, which will be publicly available to the space weather community. We will develop means to compute and nowcast the full solar spectrum in high resolution from these observational data. On the theoretical side we will develop new solar atmosphere models for the interpretation of the irradiance variability and refining our understanding of the physical origin of the solar variability. The final product will be a new improved reconstruction of the spectral and total solar irradiance back to 7000 BC, which will be a crucial as forcing input to climate models for understanding change in historical times.

Further information (English)

Full name of research-institution/enterprise: Physikalisch-Meteorologisches Observatorium Davos Weltstrahlungszentrum Director PMOD /WRC

Partners and International Organizations (English)

AT; BE; BG; HR; CY; CZ; DK; FI; FR; DE; EL; HU; IL; IT; NO; RO; ES; UK; RU

Abstract (English)

The project is aimed on analyzing measurements of Spectral Solar Irradiance (SSI), which have been obtained by PREMOS/PICARD, which is a space experiments built at PMOD/WRC. Although it has been known since 1978 that the solar irradiance is not constant but instead varies on different time scales, a complete picture of the solar variability is still missing. Knowledge of the solar irradiance is important because it is impacting Earths climate on long time scales and the so termed “space weather” on shorter time scales. Nowadays several datasets are available for past SSI variations, which are based on different reconstruction approaches and satellite measurements. However, the substantial disagreements between these data sets lead to different atmospheric responses when they are used in the climate models. Thus the task of monitoring the Spectral Solar Irradiance (SSI) as well as creating a tool for its reconstruction to the past and now casting remains of high importance. There are two objectives within this project. The primary objective is the analysis of the PREMOS/PICARD measurements to improve our understanding of the solar irradiance variability. The second objective is to develop a new solar irradiance model, COSIR (COde of Solar Irradiance Reconstruction), based on the evolution of the magnetic features on the solar surface. From the UV to infrared spectral range, the COSIR model has been very successful at reproducing the solar irradiance variability on short timescales.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C11.0135