Changes in temperature and precipitation extremes in the CMIP5 ensemble

Twenty-year temperature and precipitation extremes and their projected future changes are evaluated in an ensemble of climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5), updating a similar study based on the CMIP3 ensemble. The projected changes are documented for three radiative forcing scenarios. The performance of the CMIP5 models in simulating 20-year temperature and precipitation extremes is comparable to that of the CMIP3 ensemble. The models simulate late 20th century warm extremes reasonably well, compared to estimates from reanalyses. The model discrepancies in simulating cold extremes are generally larger than those for warm extremes. Simulated late 20th century precipitation extremes are plausible in the extratropics but uncertainty in extreme precipitation in the tropics and subtropics remains very large, both in the models and the observationally-constrained datasets. Consistent with CMIP3 results, CMIP5 cold extremes generally warm faster than warm extremes, mainly in regions where snow and sea-ice retreat with global warming. There are tropical and subtropical regions where warming rates of warm extremes exceed those of cold extremes. Relative changes in the intensity of precipitation extremes generally exceed relative changes in annual mean precipitation. The corresponding waiting times for late 20th century extreme precipitation events are reduced almost everywhere, except for a few subtropical regions. The CMIP5 planetary sensitivity in extreme precipitation is about 6 %/°C, with generally lower values over extratropical land.     

珠江流域1961-2007年气候变化及2011-2060年预估分析

 根据珠江流域1961-2007年气温、降水量观测资料和ECHAM5/MPI-OM模式2011-2060年预估结果,分析了流域过去47 a的气温和降水量变化,并预估未来50 a变化趋势。结果表明,在全球变暖的背景下,过去47 a温度呈上升趋势,约升高1.8℃。冬季增温最明显,夏季最弱。未来50 a流域温度仍呈上升趋势,A1B情景下升幅约1.9℃,并且年际变化增强。A2和B1两种排放情景下秋季升温最显著,冬季最弱,A1B排放情景与此相反。过去47 a秋季降水量呈减少趋势;春、夏、冬季和年降水量均呈增加趋势。未来50 a降水总体呈增加趋势,A1B排放情景降水增加最多,约为230 mm。A2、A1B和B1情景下降水季节分配未发生显著变化。年降水和冬季降水的年际变率增强,秋季减弱。     

On the evaluation of an integral connected with the thermonuclear reaction rate in closed form

The standard expression of the reaction rate for low-energy, nonresonant nuclear reactions in nondegenerate plasma contains a parameter-dependent integral which in all previous calculations with physical or astrophysical background is considered as not capable of being evaluated in a closed form. So one usually resorts to approximation methods concerning large values of the parameter. At first we point out that CONSUL (1964) has given a series representation of the integral which was identified with a MEIJER 's G-function by MATHAI (1971). Next, in view of a physically more exact determination of the reaction rate formula, especially in connection with calculations concerning stellar energy generation, we consider a more general integral containing the mentioned one as special case and give an approximation-free representation by means of MEIJER 's G-function. The G-function so obtained may be conceived as complex-valued continuation of CONSUL 's series representation of a certain class of integrals contained in the considered one. From the series we extract a small parameter approximation of the special integral.     

Metadolerite age relationships in the Dalradian of northwest Donegal,Ireland and their orogenic significance

The structural relationships of several intrusive sheets belonging to the extensive metadolerite suite of the Appin (lower) Dalradian rocks of the Creeslough area, northwest Donegal, Ireland have been examined. It is concluded that, relative to the regional chronology of deformation of the enclosing metasediments, sheet emplacement has occurred: pre-D2; syn-D2; between D2 and D3; and syn-D3. The height of activity came in the post-D2, pre-D3 interval and coincided with the peak of regional metamorphism in the area. These relationships in Donegal are compared with those of the pretectonic basic rocks of the southwest Highlands and models are discussed.     

Photometrische Kalibrierung von Schmidtspiegelaufnahmen durch ein bildteilendes Hilfsprisma

Plates of the Tautenburg Schmidt can be calibrated with the aid of a beam-splitting prisma only if Schraffierkassette plates are used. The effects of image structure, scintillation and intermittence on in-focus images are different for the main component and the prismatic companion. Therefore, such plates cannot be used to set up a photometric scale.     

Erste Ergebnisse der Erprobung des photometrischen Zwillingsreflektors

First measurements of the short time variations of Ap stars with the twin telescope show a nonlinear drift caused by a sensibility of the amplifier depending on temperature. Moreover we found a dependence of the impulse rate on the position of the star image in the diaphragm. Special test measurements with a simple incandescent lamp show that this telescope gives results with an accuracy of ± 0.002 mag after elimination of these effects.     

Statistical Properties of Ribbon Evolution and Reconnection Electric Fields in Eruptive and Confined Flares

A statistical study of the chromospheric ribbon evolution in H\(\alpha\) two-ribbon flares was performed. The data set consists of 50 confined (62%) and eruptive (38%) flares that occurred from June 2000 to June 2015. The flares were selected homogeneously over the H\(\alpha\) and Geostationary Operational Environmental Satellite (GOES) classes, with an emphasis on including powerful confined flares and weak eruptive flares. H\(\alpha\) filtergrams from the Kanzelhöhe Observatory in combination with Michelson Doppler Imager (MDI) and Helioseismic and Magnetic Imager (HMI) magnetograms were used to derive the ribbon separation, the ribbon-separation velocity, the magnetic-field strength, and the reconnection electric field. We find that eruptive flares reveal statistically larger ribbon separation and higher ribbon-separation velocities than confined flares. In addition, the ribbon separation of eruptive flares correlates with the GOES SXR flux, whereas no clear dependence was found for confined flares. The maximum ribbon-separation velocity is not correlated with the GOES flux, but eruptive flares reveal on average a higher ribbon-separation velocity (by ≈?10 km?s^?1). The local reconnection electric field of confined (\(cc=0.50 \pm0.02\)) and eruptive (\(cc=0.77 \pm0.03\)) flares correlates with the GOES flux, indicating that more powerful flares involve stronger reconnection electric fields. In addition, eruptive flares with higher electric-field strengths tend to be accompanied by faster coronal mass ejections.     

Shock waves and type II radiobursts in the interplanetary medium

The planetary radio astronomy experiment on the Voyager spacecraft observed several type II solar radiobursts at frequencies below 1.3 MHz; these correspond to shock waves at distances between 20R and 1 AU from the Sun. We study the characteristics of these bursts and discuss the information that they give on shock waves in the interplanetary medium and on the origin of the high energy electrons which give rise to the radioemission. The relatively frequent occurence of type II bursts at large distances from the Sun favors the hypothesis of the emission by a longitudinal shockwave. The observed spectral characteristics reveal that the source of emission is restricted to only a small portion of the shock. From the relation between type II bursts, type III bursts and optical flares, we suggest that some of the type II bursts could be excited by type III burst fast electrons which catch up the shock and are then trapped.