A novel model to assess soil productivity in the dry-hot valleys of China

Accurate evaluation of soil productivity has been a long-standing challenge. Although numerous models for productivity assessment exist, most are cumbersome to use and require substantial parameter inputs. We developed a new empirical soil productivity model based on field investigations of soil erosion, soil physicochemical properties, and crop yields in the dry-hot valleys (DHVs) in China. We found that soil pH, and organic matter and available potassium contents significantly affected crop yields under eroded conditions of the DHVs. Moreover, available potassium content was the key factor affecting soil productivity. We then modified an existing soil productivity model by adding the following parameters: contents of effective water, potassium, organic matter, and clay, soil pH, and root weighting factor. The modified soil productivity model explained 63.5% of the crop yield. We concluded that the new model was simple, realistic, and exhibited strong predictability. In addition to providing an accurate assessment of soil productivity, our model could potentially be applied as a soil module in comprehensive crop models.     

More than two hundred and fifty thousand spectroscopic binary or variable star candidates discovered by LAMOST

About 786.4 thousand stars were observed by LAMOST twice or more during the first stage of its spectroscopic survey. The radial velocity differences for about 256 thousand targets are larger than10 km s^-1 and they are possible spectroscopic binary or variable candidates(SBVCs). It is shown that most SBVCs are slightly metal poorer than the Sun. There are two peaks in the temperature distribution of SBVCs around 5760 K and 4870 K, while there are three peaks in the distribution of the gravitational acceleration at 2.461, 4.171 and 4.621 cm s^-2. The locations of SBVCs on the [Fe/H]-T, [Fe/H]-log g, log g-T and H-R diagrams are investigated. It is found that the detected SBVCs could be classified into four groups. The first group has higher log g～4.621 and lower T ～ 4870 K which are mainly cool red dwarf binaries. The second group of SBVCs has logg around 4.171 cm s^-2 that includes binaries and pulsating stars such as δSet and γ Dor variables. The gravitational accelerations of the third group of SBVCs are higher and some of them are below the zero-age main sequence. They may be contact binaries in which the primary components are losing energy to the secondaries in the common envelopes and are at a special stellar evolutionary stage.The last group is composed of giants or supergiants with log g around 2.461 cm s^-2 that may be evolved pulsating stars. One target(C134624.29+333921.2) is confirmed as an eclipsing binary with a period of 0.65 days. A preliminary analysis suggests that it is a detached binary with a mass ratio of 0.46. The primary fills its critical Roche lobe by about 89%, indicating that mass transfer will occur between the two components.     

The Photospheric Convection Spectrum

Spectra of the cellular photospheric flows are determined from observations acquired by the MDI instrument on the SOHO spacecraft. Spherical harmonic spectra are obtained from the full-disk observations. Fourier spectra are obtained from the high-resolution observations. The p-mode oscillation signal and instrumental artifacts are reduced by temporal filtering of the Doppler data. The resulting spectra give power (kinetic energy) per wave number for effective spherical harmonic degrees from 1 to over 3000. Significant power is found at all wavenumbers, including the small wavenumbers representative of giant cells. The time evolution of the spectral coefficients indicates that these small wavenumber components rotate at the solar rotation rate and thus represent a component of the photospheric cellular flows. The spectra show distinct peaks representing granules and supergranules but no distinct features at wavenumbers representative of mesogranules or giant cells. The observed cellular patterns and spectra are well represented by a model that includes two distinct modes – granules and supergranules.     

Coupled convection and tidal dissipation in Europa’s ice shell using non-Newtonian grain-size-sensitive (GSS) creep rheology

We present self-consistent, fully coupled two-dimensional (2D) numerical models of thermal evolution and tidal heating to investigate how convection interacts with tidal dissipation under the influence of non-Newtonian grain-size-sensitive creep rheology (plausibly resulting from grain boundary sliding) in Europa’s ice shell. To determine the thermal evolution, we solved the convection equations (using finite-element code ConMan) with the tidal dissipation as a heat source. For a given heterogeneous temperature field at a given time, we determined the tidal dissipation rate throughout the ice shell by solving for the tidal stresses and strains subject to Maxwell viscoelastic rheology (using finite-element code Tekton). In this way, the convection and tidal heating are fully coupled and evolve together. Our simulations show that the tidal dissipation rate can have a strong impact on the onset of thermal convection in Europa’s ice shell under non-Newtonian GSS rheology. By varying the ice grain size (1-10 mm), ice-shell thickness (20-120 km), and tidal-strain amplitude (0-4 × 10⁻⁵), we study the interrelationship of convection and conduction regimes in Europa’s ice shell. Under non-Newtonian grain-size-sensitive creep rheology and ice grain size larger than 1 mm, no thermal convection can initiate in Europa’s ice shell (for thicknesses <100 km) without tidal dissipation. However, thermal convection can start in thinner ice shells under the influence of tidal dissipation. The required tidal-strain amplitude for convection to occur decreases as the ice-shell thickness increases. For grain sizes of 1-10 mm, convection can occur in ice shells as thin as 20-40 km with the estimated tidal-strain amplitude of 2 × 10⁻⁵ on Europa.     

辽宁中尺度数值模式产品和T213产品对比检验分析

利用国家级的气象预报产品质量客观检验评价系统,对辽宁中尺度模式预报MM5和T213数值预报的结果分别进行检验分析.检验类型分为历史资料检验和实时资料检验,检验要素包括地面降水、气温和高空500 hPa环流.检验结果显示,对于降水、气温的预报MM5模式预报检验结果优于T213数值预报,而对于500 hPa环流的检验结果T213更可信.     

Periodicities in Global Mean TEC from GNSS Observations

As an important measurement parameter, global total electron content (TEC) is appropriate for the study of the Sun–Earth connection. In this paper, the wavelet technique is employed to investigate the periodicities in global mean TEC during 1995–2008. Analysis results show several remarkable components (including 27-day, semiannual and annual cycles) existing in global mean TEC with obvious time-variable characteristics, besides 11-year cycle. After analyzing sunspot numbers and solar extreme ultra-violet (EUV) radiation variations during this time period, except for semiannual variations, close correlation between global mean TEC and solar variations is found, especially, a strong resemblance of the 27-day fluctuation exists in global mean TEC, sunspot and solar EUV radiation variations.     

Turbulence Heating for Protons in High-Speed Solar Wind

In high-speed solar wind, propagating Alfvén waves can be transferred into fast magnetosonic waves. When both the magnetic field strength and Alfvén wave velocity approach zero, fast magnetosonic waves will be transferred into ion-acoustic waves. As the phase velocity of ion-acoustic waves is slightly greater than the thermal velocity of protons, the turbulence energy of ion-acoustic waves can largely be absorbed by protons and can cause the mean temperature of protons to be greater than that of electrons by stochastic turbulence heating of ion-acoustic waves for protons.     

Application of Astronomic Time-latitude Residuals in Earthquake Prediction

After the earthquake (Ms = 6.1) occurred in Luquan county of Yunnan province on April 18, 1985, the relationship between major earthquakes and astronomical time-latitude residuals (ATLR) of a photoelectric astrolabe in Yunnan Observatory was analyzed. ATLR are the rest after deducting the effects of Earth’s whole motion from the observations of time and latitude. It was found that there appeared the anomalies of the ATLR before earthquakes which happened in and around Yunnan, a seismic active region. The reason of the anomalies is possibly from change of the plumb line due to the motion of the groundmass before earthquakes. Afterwards, using studies of the anomalous characters and laws of ATLR, we tried to provide the warning information prior to the occurrence of a few major earthquakes in the region. The significant synchronous anomalies of ATLR of the observatory appeared before the earthquake of magnitude 6.2 in Dayao county of Yunnan province, on July 21, 2003. It has been again verified that the anomalies possibly provide the prediction information for strong earthquakes around the observatory.     

J1128+592: a highly variable IDV source

Short time‐scale radio variations of compact extragalactic radio quasars and blazars known as IntraDay Variability (IDV) can be explained in at least some sources as a propagation effect; the variations are interpreted as scintillation of radio waves in the turbulent interstellar medium of the Milky Way. One of the most convincing observational arguments in favor of a propagation‐induced variability scenario is the observed annual modulation in the characteristic time scale of the variation due to the Earth's orbital motion. So far there are only two sources known with a well‐constrained seasonal cycle. Annual modulation has been proposed for a few other less well‐documented objects. However, for some other IDV sources source‐intrinsic structural variations which cause drastic changes in the variability time scale were also suggested. J1128+592 is a recently discovered, highly variable IDV source. Previous, densely time‐sampled flux‐density measurements with the Effelsberg 100‐m radio telescope (Germany) and the Urumqi 25‐m radio telescope (China), strongly indicate an annual modulation of the time scale. The most recent 4 observations in 2006/7, however, do not fit well to the annual modulation model proposed before. In this paper, we investigate a possible explanation of this discrepancy. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)