Blazars with strong emission lines were found to be associated mostly with broad-line type 1 Active Galactic Nuclei (AGN). Hitherto, evidence for blazars identified with Narrow Line Seyfert 1 (NLS1) AGN was limited to very few individual cases. Here we present a comprehensive study of a sample of 23 genuine radio-loud NLS1 galaxies which have the radio-loudness parameters, the ratio of radio (21 cm) to optical (4400Å) luminosity, greater than 100. The sample, drawn from the SDSS and FIRST, is homogeneous and the largest of this kind. A significant fraction of the sample objects show interesting radio to X-ray properties that are unusual to most of the previously known radio-loud NLS1 AGN, but are reminiscent of blazars. These include flat radio spectra, large amplitude flux and spectral variability, compact VLBI cores, very high brightness temperatures (10 11−14 K) derived from variability, enhanced optical emission in excess of the normal ionising continuum, flat X-ray spectra, and blazar-like SEDs. We interpret them as evidence for the postulated blazar nature of these very radio-loud NLS1 AGN, which might possess at least moderately relativistic jets. We suggest that those steep spectrum radio-loud NLS1 AGN in the sample are of the same population but with their radio jets aligned at large angles to the lines-of-sight. Intrinsically, some of the objects have relatively low radio power and would have been classified as radio-intermediate AGN.The black hole masses, estimated from the broad Balmer line width and luminosity, are within 10 6−8 M ⊙ , and the inferred Eddington ratios are around unity. Unless the black hole masses are largely under-estimated, our result stretches the low mass end of the black holes of luminous, fast accreting radio-loud AGN to a smaller mass regime (the order of 10 6 M ⊙ ) in the black hole mass-radio-loudness space where other normal AGN are seldom found. The results imply that radio-loud AGN may be powered by black holes with moderate masses (∼ 10 6−7 M ⊙ ) accreting at high rates (Eddington ratios up to unity or higher). The host galaxies of a few nearby objects appear to be disk-like or merger; and some of the objects show imprints of young stellar populations in their SDSS spectra. We find that some of the objects, despite having strong emission lines, resemble high-energy peaked BL Lacs in their SED with the synchrotron component peaked at around the UV; such objects constitute an intriguingly high fraction of the sample. The radio sources of the sample are ubiquitously compact. They are smaller than at most several tens of kilo-parsecs, suggesting a possible link with compact steep-spectrum radio sources. Given the peculiarities of blazar-like NLS1 galaxies, questions arise as to whether they are plain downsizing extensions of normal radio-loud AGN, or whether they form a previously unrecognised population.

Hourly observational records and 6-hourly reanalysis data were used to investigate the influences of large-scale forcings on the diurnal variation of summer rainfall along the Yangtze River (YR). The results show that longduration (more than six hours) rainfall events dominate the summer rainfall along the YR. These events tend to start during the night and to peak after several hours of development. The eastward-delayed initiation of the nocturnal long-duration rainfall events is thought to be due to the diurnal clockwise rotation of the lowtropospheric circulation, especially the accelerated nocturnal southwesterlies. In the early evening, the anomalous easterly flow toward the Tibetan Plateau (TP) causes low-level convergence over the Plateau's eastern slope that induces the formation of rainfall in the upper YR valley. The anomalous wind sequentially rotates clockwise to a southerly flow at midnight and accelerates the meridional wind in the middle valley, resulting in the initiation of rainfall between 2300 and 0300 LST. In the early morning, the accelerated southwesterlies in southern China, when combined with decelerated winds in the north of the YR, causes a strong convergence along the YR and contributes to the early morning rainfall in the lower valley. Furthermore, the development of the convection systems is suppressed in the afternoon by the mid-and low-level warm advection downstream from the TP. This helps explain why long-duration events do not typically start in the afternoon in the upper YR valley.

Quaternary Research 52 (1999) 369-380. doi:10.1006/qres.1999.2072Received by publisher: 1999-05-14Harvest Date: 2016-01-04 12:20:38DOI: 10.1006/qres.1999.2072Page Range: 369-38

Context. The quasar 3C 279 is among the most extreme blazars in terms of luminosity and variability of flux at all wavebands. Its variations in flux and polarization are quite complex and therefore require intensive monitoring observations at multiple wavebands to characterise and interpret the observed changes. Aims. In this paper, we present radio-to-optical data taken by the WEBT, supplemented by our VLBA and RXTE observations, of 3C 279. Our goal is to use this extensive database to draw inferences regarding the physics of the relativistic jet. Methods. We assemble multifrequency light curves with data from 30 ground-based observatories and the space-based instruments SWIFT (UVOT) and RXTE, along with linear polarization vs. time in the optical R band. In addition, we present a sequence of 22 images (with polarization vectors) at 43 GHz at resolution 0.15 milliarcsec, obtained with the VLBA. We analyse the light curves and polarization, as well as the spectral energy distributions at different epochs, corresponding to different brightness states. Results. We find that the IR-optical-UV continuum spectrum of the variable component corresponds to a power law with a constant slope of −1.6, while in the 2.4-10 keV X-ray band it varies in slope from −1.1 to −1.6. The steepest X-ray spectrum occurs at a flux minimum. During a decline in flux from maximum in late 2006, the optical and 43 GHz core polarization vectors rotate by ∼300• . Conclusions. The continuum spectrum agrees with steady injection of relativistic electrons with a power-law energy distribution of slope −3.2 that is steepened to −4.2 at high energies by radiative losses. The X-ray emission at flux minimum comes most likely from a new component that starts in an upstream section of the jet where inverse Compton scattering of seed photons from outside the jet is important. The rotation of the polarization vector implies that the jet contains a helical magnetic field that extends ∼20 pc past the 43 GHz core.