ALBERT

Description: [1]  In this study we quantify the contribution of individual large-scale waves to ionospheric electrodynamics, and examine the dependence of the ionospheric perturbations on solar activity. We focus on migrating diurnal tide (DW1) plus mean winds, migrating semidiurnal tide (SW2), quasi-stationary planetary wave 1 (QSPW1), and nonmigrating semidiurnal westward wave 1 (SW1) under northern winter conditions, when QSPW1 and SW1 are climatologically strong. From TIME-GCM simulations under solar minimum conditions, it is found that the mean winds and DW1 produce a wave 2 pattern in equatorial vertical E  ×  B drift that is upward in the morning and around dusk. The modeled SW2 also produces a wave 2 pattern in the ionospheric vertical drift that is nearly a half wave cycle out of phase with that due to mean winds and DW1. SW1 can cause large vertical drifts around dawn, while QSPW1 does not have any direct impact on the vertical drift. Wind components of both SW2 and SW1 become large at mid to high latitudes in the E-region, and kernel functions obtained from numerical experiments reveal that they can significantly affect the equatorial ion drift, likely through modulating the E-region wind dynamo. The most evident changes of total ionospheric vertical drift when solar activity is increased are seen around dawn and dusk, reflecting the more dominant role of large F-region Pedersen conductivity and of the F-region dynamo under high solar activity. Therefore, the lower atmosphere driving of the ionospheric variability is more evident under solar minimum conditions, not only because variability is more identifiable in a quieter background, but also because the E-region wind dynamo is more significant. These numerical experiments also demonstrate that the amplitudes, phases and latitudinal and vertical structures of large-scale waves are important in quantifying the ionospheric responses.

Description: Author(s): C. Liu (刘晨), S. Y. Wang (王守宇), B. Qi (亓斌), D. P. Sun (孙大鹏), S. Wang (王硕), C. J. Xu (徐长江), L. Liu (刘雷), P. Zhang (张盼), Z. Q. Li (李志泉), B. Wang (王彬), X. C. Shen (沈晓晨), M. R. Qin (秦慕容), H. L. Liu (刘红亮), Y. Gao (高原), L. H. Zhu (竺礼华), X. G. Wu (吴晓光), G. S. Li (李广生), C. Y. He (贺创业), and Y. Zheng (郑云) High spin states in 108 Ag have been studied via in-beam γ spectroscopy techniques using the 104 Ru( 7 Li, 3 n ) reaction. The previously known level scheme has been extended, and a new band structure has been established. The configurations have been tentatively assigned to all observed rotational bands.... [Phys. Rev. C 88, 037301] Published Tue Sep 17, 2013

Description: Author(s): J. Rissanen, R. M. Clark, K. E. Gregorich, J. M. Gates, C. M. Campbell, H. L. Crawford, M. Cromaz, N. E. Esker, P. Fallon, U. Forsberg, O. Gothe, I.-Y. Lee, H. L. Liu, A. O. Machiavelli, P. Mudder, H. Nitsche, G. Pang, A. Rice, D. Rudolph, M. A. Stoyer, A. Wiens, and F. R. Xu The 257 Rf isotope has been populated via the 208 Pb( 50 Ti, n ) fusion-evaporation reaction and delayed γ -ray and electron decay spectroscopy has been performed. The existence of a high- K isomeric state in 257 Rf has been confirmed. The isomeric state decays into a rotational band based on the 11/2 − [725]... [Phys. Rev. C 88, 044313] Published Fri Oct 11, 2013

Description: The targeting and functions of miRNA-383 are mediated by FMRP during spermatogenesis Cell Death and Disease 4, e617 (May 2013). doi:10.1038/cddis.2013.138 Authors: H Tian, Y-X Cao, X-S Zhang, W-P Liao, Y-H Yi, J Lian, L Liu, H-L Huang, W-J Liu, M-M Yin, M Liang, G Shan & F Sun

Description: The swimming of a bacterium or a biomimetic nanobot driven by a rotating helical flagellum is often interpreted using the resistive force theory developed by Gray and Hancock and by Lighthill, but this theory has not been tested for a range of physically relevant parameters. We test resistive force theory...

Description: [1]  Ionospheric day-to-day variability is a ubiquitous feature, even in the absence of appreciable geomagnetic activities. Although meteorological perturbations have been recognized as an important source of the variability, it is not well represented in previous modeling studies, and the mechanism is not well understood. This study demonstrates that TIME-GCM (Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model) constrained in the stratosphere and mesosphere by the hourly Whole Atmosphere Community Climate Model (WACCM) simulations is capable of reproducing observed features of day-to-day variability in the thermosphere-ionosphere. Realistic weather patterns in the lower atmosphere in WACCM was specified by Modern Era Retrospective reanalysis for Research and Application (MERRA). The day-to-day variations in mean zonal wind, migrating and non-migrating tides in the thermosphere, vertical and zonal E  ×  B drifts, and ionosphere F2 layer peak electron density (NmF2) are examined. The standard deviations of the drifts and NmF2 display local time and longitudinal dependence that compare favorably with observations. Their magnitudes are 50% or more of those from observations. The day-to-day thermosphere and ionosphere variability in the model is primarily caused by the perturbations originated in lower atmosphere, since the model simulation is under constant solar minimum and low geomagnetic conditions.

Description: Author(s): G. X. Dong, X. B. Wang, H. L. Liu, and F. R. Xu The abnormally large collectivity of neutron-rich magnesium isotopes in the “island of inversion” has not been well understood. It has been commented that the unexpectedly large deformations observed in the magnesium isotopes are attributed to the neutron f 7/2 intruder orbits involved remarkably eve... [Phys. Rev. C 88, 024328] Published Fri Aug 30, 2013

Description: Author(s): H. L. Liu and F. R. Xu Configuration-constrained potential-energy-surface calculations with reflection asymmetry show enhanced octupole correlations in the K π =6 − states with configuration ν 5/2 + [633]⊗ ν 7/2 − [743] in N =142,144 isotones, where a 33.5- μ s isomer has been observed in 234 U. High- K isomeric states in other nuclei a... [Phys. Rev. C 87, 067304] Published Fri Jun 14, 2013

Description: [1]  The Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter (EAKF) is employed to perform data assimilation in the Whole Atmosphere Community Climate Model (WACCM). To demonstrate the potential of the WACCM + DART for studying short-term variability in the mesosphere and lower thermosphere (MLT), results are presented based on the assimilation of synthetic observations that are sampled from a known model truth. We assimilate temperature and wind from radiosondes and aircraft, satellite drift winds, and COSMIC refractivity in the lower atmosphere, and SABER temperature observations in the middle/upper atmosphere. Relative to an unconstrained WACCM simulation, the assimilation of only lower atmosphere observations reduces the global root mean square error (RMSE) in zonal wind by up to 40% at MLT altitudes. Using data assimilation to constrain the lower atmosphere can therefore provide significant insight into MLT variability. The RMSE in the MLT is reduced by an additional 10-15% when SABER observations are also assimilated. The WACCM + DART is shown to be able to reproduce the large-scale features of the day-to-day variability in the zonal mean, migrating, and nonmigrating tides in the MLT. Though our simulation results are based on idealized conditions, they demonstrate that the WACCM + DART can reproduce the day-to-day variability in the MLT. Assimilation of real observations in the WACCM + DART will therefore enable significant insight into the real day-to-day dynamical variability from the surface to the lower thermosphere.

Description: [1]  Based on Whole Atmosphere Community Climate Model (WACCM) simulations, Pedatella and Liu [2012] recently demonstrated that significant interannual variability occurs in migrating and nonmigrating tides in the mesosphere and lower thermosphere (MLT) due to the El Niño Southern Oscillation. The role of changes in tropospheric forcing, changes in the zonal mean atmosphere, and planetary wave-tide interactions on generating the tidal variability in the MLT are investigated in the present study. The ENSO driven variability in the migrating diurnal tide ( DW 1) is found to be primarily due to changes in the tropospheric forcing of the DW 1. Changes in tropospheric forcing are also the source of the changes in the eastward propagating nonmigrating diurnal tide with zonal wavenumber 3 ( DE 3). However, changes in the zonal mean atmosphere also contribute to interannual variability of the DE 3 due to the ENSO. Variability in the eastward propagating nonmigrating diurnal tide with zonal wavenumber 2 ( DE 2) is largely due to changes in the background atmosphere, with a smaller additional contribution due to changes in tropospheric forcing. Variability in the westward propagating semidiurnal tide with zonal wavenumber 4 ( SW 4) is believed to be due to changes in planetary waves during the ENSO which will enhance generation of the SW 4 through the nonlinear interaction of the migrating semidiurnal tide and stationary planetary waves with zonal wavenumber 2. The influence of the interannual tidal variability on the longitude structure of the low-latitude ionosphere is also investigated in the present study. Comparison of El Niño and La Niña time periods reveals that the ENSO introduces changes of ~2-4 ms −1 in the daytime vertical drift velocity at certain longitudes. Simulation results further illustrate that the variability in the vertical drift velocity drives interannual variability in the low-latitude daytime F-region maximum electron density (NmF2). The results demonstrate that the ENSO introduces variability of ~10-30% in the MLT and ~10-15% in the ionosphere. The ENSO should therefore be considered as a potentially significant source of variability in the Earth's upper atmosphere.