Opera: Objective-Prism Reduction Package

Surveys of star-forming galaxies are of vital importance to constrain galactic evolution theories. One of the most successful searching methods is the objective-prism (OP) technique, which can register thousands of low resolution spectra in large areas. The UCM-CIDA (Universidad Complutense de Madrid-Centro de Investigación F. J. Duarte) project expects to cover 150 square degrees and detect ∼ 2000 Hα emission line galaxies. OPERA (Objective Prism Enhanced Reduction Algorithms) is an automatic method to handle and analyze such amount of data. It goes trough the detection of the objects in the image, extraction of one-dimensional spectra and identification of the emission line feature. The main advantages of a method of this kind are: 1) to avoid subjectivity inherent to visual inspection used in past studies; and 2) the ability to obtain physical parameters without follow-up spectroscopy. This revised version was published online in July 2006 with corrections to the Cover Date.     

Deriving Wind Force Terms from Nautical Reports Through Content Analysis. The Spanish and French Cases

Records of wind strength taken onboard Spanish and French ships during the 1750–1850 period have been digitized and examined using content analysis techniques to derive the equivalent wind strength in terms of the current Beaufort scale, this conversion being a key step in any attempt to compare ancient records with modern climatologies. During the analysis it was evident that Spanish and French officers used a great number of different terms to describe the wind force. However, when the records are analyzed and homogenized, a broadly common and essentially narrow vocabulary was identified, indicating that, at this period, a great effort had been made to regulate the maritime language. Using contemporary dictionaries and navigation manuals, an equivalence was established between the original wind force terms and the Beaufort scale.     

Interannual Variability of the Annual Cycle of Temperature over Northern Africa

In this study, the imprints of two major atmospheric variability modes - ENSO and NAO - on the annual cycle of temperature over Northern Africa, a region sensitive to both modes, are investigated. Results from adjusting the annual cycle from daily data on a high resolution grid, indicate that both NAO and ENSO are able to influence significantly the amplitude and phase of the seasonal cycle and, consequently, that interannual trends found in amplitude and phase can be not exclusively due to greenhouse gases effects.