Evaluation of Atmospheric Circulation in the Southern Hemisphere in 20CRv2

Evaluation of the mean climate and climate variability in the Southern Hemisphere(SH)in the Twentieth Century Reanalysis data version 2(20CRv2)is conducted and the results are compared with the NCEP/NCAR version 2 Reanalysis data(NCEPv2)and the Hadley Center sea-level pressure data(HadSLPv2).The results show that SH polar High,SH subtropical High,upper level split jet,cross-equatorial flow,Antarctic Oscillation(AAO),and the pattern of Pacific-South-America(PSA)has been effectively captured by 20CRv2 during1979–2010,with an apparent zonal asymmetry of AAO in the austral winter(June-July-August,JJA).The notable upward linear trend of AAO in the entire period of 1871–2010 is represented in both 20CRv2 and HadSlPv2.The most remarkable discrepancy of the SH climate variability between 20CRv2 and HadSLPv2 occurred in 1897–1920and was partly caused by such factors as the paucity of meteorological and oceanographic data in the SH to be assimilated,the handling of the specified sea-ice concentration in South Pole,and imperfect climate models.The consistency of these reanalysis data is increased with the use of a large amount of satellite observation and radiosonde data,particularly after 1979.     

Observations of EUV and soft X-ray recurring jets in an active region

We present simultaneous observations of three recurring jets in EUV and soft X-ray (SXR), which occurred in an active region on 2007 June 5. By comparing their morphological and kinematic characteristics in these two different wavelengths, we found that EUV and SXR jets had similar locations, directions, sizes and velocities. We also analyzed their spectral properties by using six spectral lines from the EUV Imaging Spectrometer (EIS) onboard Hinode and found that these jets had temperatures from 0.05 to 2....     

Potential forest fire danger over Northern Eurasia: Changes during the 20th century

Significant climatic changes over Northern Eurasia during the 20th century have been reflected in numerous variables of economic, social, and ecological interest, including the natural frequency of forest fires. For the former USSR, we are now using the Global Daily Climatology Network and a new Global Synoptic Data Network archive, GSDN, created jointly by U.S. National Climatic Data Center and Russian Research Institute for Hydrometeorological Information. Data from these archives (approximately 1500 of them having sufficiently long meteorological time series suitable for participation in our analyses) are employed to estimate systematic changes in indices used in the United States and Russia to assess potential forest fire danger. We use four indices: (1) Keetch–Byram Drought Index, (KBDI; this index was developed and widely used in the United States); (2) Nesterov, (3) Modified Nesterov, and (4) Zhdanko Indices (these indices were developed and widely used in Russia). Analyses show that after calibration, time series of the days with increased potential forest fire danger constructed using each of these three indices (a) are well correlated and (b) deliver similar conclusions about systematic changes in the weather conditions conducive to forest fires. Specifically, over the Eastern half of Northern Eurasia (Siberia and the Russian Far East) statistically significant increases in indices that characterize the weather conditions conducive to forest fires were found. These areas coincide with the areas of most significant warming during the past several decades south of the Arctic Circle. West of the Ural Mountains, the same indices show a steady decrease in the frequency of “dry weather summer days” during the past 60 yr. This study is corroborated with available statistics of forest fires and with observed changes in drought statistics in agricultural regions of Northern Eurasia.     

LAND RECLAMATION PROCESS IN NORTHEAST CHINA SINCE 1900

Landuse/coverchange(LUCC)isafocalthemeandemergingissueinthestudyofglobalenvironmentalchange.Humanmodificationsandalterationstotheenvironmentcauseimpactsonthesurfaceoftheearth,threatenglobalsustainabilityandlivelihoodsystems,andcontributetochangeinthebiogeochemicalcyclesoftheearth,whichinturnaffectatmosphericlevelsofgreenhouseandothertracegases.ConsequentlytheInternationalGeosphere-BiosphereProgram(IGBP)andtheInternationalHumanDimensionsProgram(IHDP)initiatedLUCCProgramtodevelopabette…     

MMIV: de SGR 1806–20 Anno Mirabili

On 27th December 2004 SGR 1806–20, one of the most active Soft γ-ray Repeaters (SGRs), displayed an extremely rare event, also known as giant flare, during which up to 10⁴⁷ ergs were released in the ∼1–1000 keV range in less than 1 s. Before and after the giant flare we carried out IR observations by using adaptive optics (NAOS-CONICA) mounted on VLT which provided images of unprecedented quality (FWHM better than 0.1″). We discovered the likely IR counterpart to SGR 1806–20 based on positional coincidence with the VLA uncertainty region and flux variability of a factor of about 2 correlated with that at higher energies. Moreover, by analysing the Rossi-XTE/PCA data we have discovered rapid Quasi-Periodic Oscillations (QPOs) in the pulsating tail of the 27th December 2004 giant flare of SGR 1806–20. QPOs at ∼92.5 Hz are detected in a 50 s interval starting 170 s after the onset of the giant flare. These QPOs appear to be associated with increased emission by a relatively hard unpulsed component and are seen only over phases of the 7.56 s spin period pulsations away from the main peak. QPOs at ∼18 and ∼30 Hz are also detected ∼200–300 s after the onset of the giant flare. This is the first time that QPOs are unambiguously detected in the flux of a Soft Gamma-ray Repeater, or any other isolated neutron star. We interpret the highest QPOs in terms of the coupling of toroidal seismic modes with Alfvén waves propagating along magnetospheric field lines. The lowest frequency QPO might instead provide indirect evidence on the strength of the internal magnetic field of the neutron star.      

Search for fast optical activity of SGR 1806-20 at the SAO RAS 6-m telescope

The region of SGR 1806-20 localization was observed during its gamma-ray activity in 2001. The observations have been performed on the 6-meter telescope of the Special Astrophysical Observatory, using the Panoramic Photometer-Polarimeter (PPP). The search for variability was performed on the 10⁻⁶–10 s time scale, and its results were compared to the properties of corresponding X-ray flares. This work has been supported by the Russian Foundation for Basic Research (grant No 04-02-17555), Russian Academy of Sciences (program “Evolution of Stars and Galaxies”), and by the Russian Science Support Foundation. The authors would also like to thank the anonymous referee for his/her valuable comments.     

TASTE IV: Refining ephemeris and orbital parameters for HAT‐P‐20b and WASP‐1b

We present four new light curves of the transiting exoplanets WASP‐1b and HAT‐P‐20b, observed within the TASTE (The Asiago Search for Transit timing variations of Exoplanets) project. We re‐analyzed light curves from the literature in a homogeneous way, calculating a refined ephemeris and orbital‐physical parameters for both objects. WASP‐1b does not show any significant Transit Timing Variation signal at the 120 s level. As for HAT‐P‐20b, we detected a deviation from our re‐estimated linear ephemeris that could be ascribed to the presence of a perturber or, more probably, to a previously unnoticed high level of stellar activity. The rotational period of HAT‐P‐20 A that we obtained from archival data (P_rot ≃ 14.5 d), combined with its optical variability and strong emission of Ca ii H & K lines, is consistent with a young stellar age (<1 Gyr) and support the hypothesis that stellar activity may be responsible of the measured deviations of the transit times. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

New aspects for new generation telescopes

A selection of future observing facilities relevant to galaxy evolution science covering the wavelength range from X-rays to the radio regime are summarized. Scientific aspects that can be investigated with these next generation telescopes are briefly discussed. While prospects look bright for highly advanced and innovative future facilities, it will be important to ensure that human resources in observational astronomy and theory – both in terms of expertise, funding, and available positions – are keeping pace with the technological developments. This revised version was published online in August 2006 with corrections to the Cover Date.