Série du marégraphe de Marseille : mesures de températures de surface de la mer de 1895 à 1956 : une correction

In 2007, a daily temperature series, which has been collected from 1885 to 1967 at the Marseilles tide recorder, was published here. Upon the available information provided by the data managing office, they were considered as sea-surface temperatures. Unfortunately they were not but air temperature inside the building. In the present paper, the authors correct this error by studying the true seawater temperature series which had been dug out after the publication of the precedent paper. The study of this slightly shorter series (1895–1956) leads to close conclusions. Along these 61 years, the warming trend of the surface seawater rises to +1.6 °C, to +1.3 °C if only January to May and December are selected and +2.2 °C during the June to November period. In the first half part of the series (1895–1925), the average value of each month distributions (except January) and annual minimal (except 1956) are significantly lower than along the second (1925–1956).     

Testing the Ep,i–Lp,iso–T0.45 correlation on a BeppoSAX and Swift sample of gamma-ray bursts

Using a sample of 14 BeppoSAX and 74 Swift GRBs with measured redshift we tested the correlation between the intrinsic peak energy of the time-integrated spectrum,   E _{p, i}   , the isotropic-equivalent peak luminosity,   L _p,iso  , and the duration of the most intense parts of the GRB computed as T _0.45 ('Firmani correlation'). For 41 out of 88 GRBs we could estimate all of the three required properties. Apart from 980425, which appears to be a definite outlier and notoriously peculiar in many respects, we used 40 GRBs to fit the correlation with the maximum likelihood method discussed by D'Agostini, suitable to account for the extrinsic scatter in addition to the intrinsic uncertainties affecting every single GRB. We confirm the correlation. However, unlike the results by Firmani et al., we found that the correlation does have a logarithmic scatter comparable with that of the   E _{p, i} – E _iso  ('Amati') correlation. We also find that the slope of the product   L _p,iso  T _0.45  is equal to ∼0.5, which is consistent with the hypothesis that the   E _{p, i} – L _p,iso– T _0.45  correlation is equivalent to the   E _{p, i} – E _iso  correlation (slope ∼0.5). We conclude that, based on presently available data, there is no clear evidence that the   E _{p, i} – L _p,iso– T _0.45  correlation is different (both in terms of slope and dispersion) from the   E _{p, i} – E _iso  correlation.     

Estimation of mean spectral directions in random seas

A method for obtaining the directional spectrum, on assuming that the frequencies of the elementary waves are all different from one another, is re-proposed in a form suitable for applications to sea states near a coast. The method is applied to an interval of 10 h during which the sea state remained basically steady state off the beach at Reggio Calabria (east coast of the Straits of Messina). It is shown that the directional spectrum converges as the length of the time series data grows. A numerical simulation of a 10 h sea state confirms that the directional spectrum converges as the length of the time series grows, and the convergence is onto the known directional spectrum used to make the numerical simulation. Through the numerical simulation, it is proved that the method, generally, is suitable for applications even with short time series of wind waves (duration of about 100T_p). Finally, it is shown that the method is not necessarily inadequate even with short records of multimodal sea states with different modal directions, modal amplitude ratios and intermodal distances.     

Investigation of Shuttle Radar Topography Mission data of the possible impact structure at Serra da Cangalha,Brazil

Abstract— The Serra da Cangalha crater structure in northeast Brazil, ?13 km in diameter, has long been widely considered to be a confirmed impact structure, based on reports of shatter cone findings. Only very limited field work has been carried out at this crater structure. Landsat Thematic Mapper (TM) and Shuttle Radar Topography Mission (SRTM) data sets for the region around this crater structure are compared here with regard to their suitability to determine first‐order structural detail of impact crater structures. The SRTM data provide very detailed information regarding drainage patterns and topography. A pronounced central ring of up to 300 m elevation above the surrounding area, two comparatively subdued intermediate rings of 6 and 10.5 km diameter, respectively, and the broad, complex crater rim of up to >100 m elevation can be distinguished in the Serra da Cangalha data. The maximum cratering‐related regional deformation (radial and concentric features) seems to be limited to a radial distance of 16–18 km from the center of the structure. A first comparison of macrostructural information from several impact structures with that from Serra da Cangalha does not yield firm trends, but the database is still very small at this stage. The varied nature of the target geology strongly influences the development of structural features in any impact event.     

The Sustainable Pumping Rate Concept: Lessons from a Case Study in Central Italy

The term sustainable pumping rate (SPR) is defined as the maximum pumping rate that can be maintained indefinitely without mining an aquifer, and is different from the concept of safe yield (SY), which takes into account also aspects related to the much wider concept of sustainability. The assessment of the SPR for the case study of Petrignano d'Assisi, an alluvial aquifer located in Central Italy, shows the need for a reliable estimate of the global water budget of the aquifer, particularly of the recharge under undisturbed conditions; however, the latter is not sufficient, because the SPR is affected also by the geometry of the aquifer, the hydraulic conductivity pattern, the variation of recharge/discharge ratio induced by the abstractions, and so on. All these aspects are analyzed by means of a numerical flow model calibrated both under undisturbed conditions (1974) and under exploitation conditions (1998 to 2004). The steady-state modeling results show that the relation between recharge and abstractions both at local and global scale is a key point in order to estimate a long-term SPR. Moreover, as it could be necessary to overexploit the aquifer for short periods, e.g., during drought episodes, the estimate of SPR must be performed also in transient conditions, in order to take into account the characteristic time of depletion and the successive recovery.     

A Comparative Analysis of Photospheric Bright Points in an Active Region and in the Quiet Sun

We present a comparative study of photometric and dynamic properties of photospheric bright points (BPs) observed at the disk centre in the active region (AR) NOAA 10912 and in the quiet Sun. We found that the average concentration of BPs is 54% larger in the AR than in the quiet Sun. We also measure a decrease of the BP concentration and an increase of their size moving away from the AR centre. However, these variations can be ascribed to the variation of the spatial resolution and image quality in the field of view of the AR dataset. We also found that BPs in the quiet Sun are associated with larger downflow motions than those measured within the AR. Finally, from our measurements of contrast and velocity along the line of sight, we deduced that BPs are less bright in high magnetic flux density regions than in quiet regions, due to a lower efficiency of convection in the former regions.