Messung und Modellierung der spektralen Sonnenstrahlung Schlussbericht

Small band measurements of spectral solar radiation by means of commercially available spectral radiometers - which are generally designed for laboratory work - require thorough aptitude tests and mostly special fitting measures. For the already available DM 150, first of all an entrance optics to correct cosine errors, a thermostatted weathercasing, as well as a special control lamp device for field use were developped. An international IEA-field intercomparison of 12 spectral radiometers in the Oberpfaffenhofen area of DLR showed deviations between the global radiation spectra of #+-#15% and #+-#40% for the best and the worst case, resp. The latter was caused by the operational requirements in the field and the mechanical instabilities of some radiometers (including the DM 150). Generally a remarkable portion of the deviations belongs to calibration uncertainties and imperfect cosine corrections. With regard to the summarized experience only principal recommendations on the use of spectral radiometers are given. Measured data of atmospheric heat radiation A and other meteorological data of 16 IEA stations were compiled in a data base at MOH to facilitate the fast uniform validation of 30 formulae for parametrization of A. For the case of sky clouded in 3 layers a parametrization formula was improved and successfully validated. A special reliable A-formula could be developped from the sufficiently high number of data of station Schleswig for the case of low cloudiness only. (orig.)Available from TIB Hannover: F96B618+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Observations and modelling of the global distribution and long-term trend of atmospheric 14CO2

Global high-precision atmospheric Δ14CO2 records covering the last two decades are presented, and evaluated in terms of changing (radio)carbon sources and sinks, using the coarse-grid carbon cycle model GRACE. Dedicated simulations of global trends and interhemispheric differences with respect to atmospheric CO2 as well as δ13CO2 and Δ14CO2, are shown to be in good agreement with the available observations (1940–2008). While until the 1990s the decreasing trend of Δ14CO2 was governed by equilibration of the atmospheric bomb 14C perturbation with the oceans and terrestrial biosphere, the largest perturbation today are emissions of 14C-free fossil fuel CO2. This source presently depletes global atmospheric Δ14CO2 by 12–14‰ yr−1, which is partially compensated by 14CO2 release from the biosphere, industrial 14C emissions and natural 14C production. Fossil fuel emissions also drive the changing north–south gradient, showing lower Δ14C in the northern hemisphere only since 2002. The fossil fuel-induced north–south (and also troposphere–stratosphere) Δ14CO2 gradient today also drives the tropospheric Δ14CO2 seasonality through variations of air mass exchange between these atmospheric compartments. Neither the observed temporal trend nor the Δ14CO2 north–south gradient may constrain global fossil fuel CO2 emissions to better than 25%, due to large uncertainties in other components of the (radio)carbon cycle

Bestimmung verdichteter Flaechenverteilungen der Globalstrahlung aus Messnetzdaten und Erhoehung der Messgenauigkeit von solarer und terrestrischer Strahlung Schlussbericht

Based on global solar radiation data from the radiometric network of Deutscher Wetterdienst and from measurements of the European meteorological satellite METEOSAT, several statistical methods were applied to the topographic and climatic conditions in the Federal Republik of Germany in order to compute and plot dense spatial distributions of global solar radiation on the regional scale. Best results were obtained by using the so-called Kriging method. The measuring accuracy of global solar radiation is increased when direct and diffuse solar radiation are measured separately. For this purpose, a so-called global solar radiation reference radiometer consisting of an absolute pyrheliometer and a pyranometer with shadow-disk on the same solar tracker was developed; for solar elevation angles above 40 and little cloudiness, #+-# 1% measuring accuracy was attained. - By test series it was demonstrated that pyranometers of types PSP and CM11 do not show aging. However, for PSP pyranometers the cosine error function is to be determined by lamps adjusted to the solar spectrum; for CM11 pyranometers, the temperature function of the responsivity is to be measured. - The measuring accuracy of atmospheric thermal radiation at simultaneous high global solar radiation is around #+-# 10%. The large scattering of given calibration and correction values was found to be the main error source. The measuring accuracy is substantially improved by ventilating the pyrgeometer and screening the direct solar radiation by a sun-tracking shadow disk. (orig.)Ausgehend von Globalstrahlungsdaten aus dem Strahlungsmessnetz des Deutschen Wetterdienstes und aus Messungen des europaeischen meteorologischen Satelliten METEOSAT wurden mehrere statistische Verfahren auf die topographischen und klimatischen Bedingungen in der Bundesrepublik Deutschland angewandt, um verdichtete Flaechenverteilungen der Globalstrahlung im regionalen Massstab zu berechnen und kartographisch darzustellen. Dabei lieferte die sog. Kriging-Methode die besten Ergebnisse. Die Messgenauigkeit der Globalstrahlung wird erhoeht, wenn direkte und diffuse Sonnenstrahlung getrennt gemessen werden. Dazu wurde ein sog. Globalstrahlungs-Referenzradiometer als Kombination von Absolut-Pyrheliometer und Pyranometer mit Schattenscheibe auf derselben Sonnennachfuehrung entwickelt, das bei Sonnenhoehenwinkeln ueber 40 und geringer Bewoelkung eine Messgenauigkeit von #+-# 1% erreicht. - Durch Testreihen wurde nachgewiesen, dass Pyranometer vom Typ PSP und CM11 keine Alterung erleiden. Bei PSP-Pyranometern ist jedoch mit sonnenaehnlichen Pruefstrahlern die Cosinusfehler-Funktion, bei CM11-Pyranometern die Temperatur-Funktion der Messempfindlichkeit zu bestimmen. - Die Messgenauigkeit der atmosphaerischen Waermestrahlung betraegt bei gleichzeitiger hoher Globalstrahlung rund #+-# 10%. Als Hauptfehlerquelle wurde die grosse Streuung der angegebenen Kalibrier- und Korrekturwerte festgestellt. Die Messgenauigkeit laesst sich erheblich verbessern, wenn das Pyrgeometer ventiliert sowie mit einer sonnennachgefuehrten Schattenscheibe von der direkten Sonnenstrahlung abgeschirmt wird. (orig.)SIGLEAvailable from TIB Hannover: F94B0633+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

The European Solar Radiation Atlas Vol.2: Database and exploitation software

CD-ROM with databases and software included; CD-Rom avec bases de données et logiciels inclusInternational audienc

The European Solar Radiation Atlas Vol.1: Fundamentals and maps

CD-ROM with databases and software included CD-Rom avec bases de données et logiciels inclusInternational audienc