A New Statistical Downscaling Scheme for Predicting Winter Precipitation in China

An effective statistical downscaling scheme was developed on the basis of singular value decomposition to predict boreal winter(December-January-February)precipitation over China.The variable geopotential height at 500 hPa(GH5)over East Asia,which was obtained from National Centers for Environmental Prediction’s Coupled Forecast System(NCEP CFS),was used as one predictor for the scheme.The preceding sea ice concentration(SIC)signal obtained from observed data over high latitudes of the Northern Hemisphere was chosen as an additional predictor.This downscaling scheme showed significantly improvement in predictability over the original CFS general circulation model(GCM)output in cross validation.The multi-year average spatial anomaly correlation coefficient increased from–0.03 to 0.31,and the downscaling temporal root-mean-square-error(RMSE)decreased significantly over that of the original CFS GCM for most China stations.Furthermore,large precipitation anomaly centers were reproduced with greater accuracy in the downscaling scheme than those in the original CFS GCM,and the anomaly correlation coefficient between the observation and downscaling results reached～0.6 in the winter of 2008.     

双线偏振雷达差分反射率因子系统误差订正

差分反射率因子ZDR易受雷达系统自身的影响而产生明显偏差,这种偏差是不随空间积累而改变的.为了保证雷达资料及其产品的质量,根据中国气象科学研究院灾害天气国家重点实验室车载C波段双线偏振多普勒雷达(C-band Polarimetric Doppler Radar on Wheel,CPDRW)的外场试验,对观测的ZDR进行了分析,并以垂直扫描数据的订正结果为参考,重点讨论了以体扫模式最高仰角下的小雨和干雪这两种自然目标物为订正对象得到的订正结果.结果表明,高仰角体扫资料的这两种自然目标物都能较好地订正ZDR的系统误差.但相较于小雨,干雪的订正效果更加稳定,是进行ZDR系统误差订正的最优气象目标物,而利用高仰角体扫资料的干雪粒子进行ZDR系统误差订正也就成为垂直扫描订正法的最佳替代方法.     

Structural controls on a geothermal system in the Tarutung Basin,north central Sumatra

The Sumatra Fault System provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity. Whereas most of the geothermal systems in Indonesia are controlled by volcanic activity, geothermal systems at the Sumatra Fault System might be controlled by faults and fractures. Exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling. We present field geological, structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the Tarutung Basin in north central Sumatra. Our results indicate that the fault pattern in the Tarutung Basin is generated by a compressional stress direction acting at a high angle to the right-lateral Sumatra Fault System. NW–SE striking normal faults possibly related to negative flower structures and NNW-SSE to NNE-SSW oriented dilative Riedel shears are preferential fluid pathways whereas ENE–WSW striking faults act as barriers in this system. The dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the Sumatra Fault System. Our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited.     

Identification of non-linear and non-stationary soil properties during the 1995 Hyogoken-nanbu earthquake

An extended Kalman filter algorithm with local iteration is presented for the identification of non-linear and non-stationary soil properties. Borehole-array strong motions were recorded at a liquefied site during the 1995 Hyogoken-nanbu earthquake. In this study, a modified Kalman filtering method in which the extended Kalman filter is iteratively used at every local time-step to track rapid parameter changes is proposed. The method is then applied to the instrumented soil layer, which is modeled by an equivalent linear model. An identification of non-linear and non-stationary soil properties was conducted successfully; and non-linear restoring force–displacement relationships including progression with time were obtained.     

连翘高产栽培技术

本文介绍了现在比较常用的W in2000操作系统下安全功能配置,如何在Internet网上采取信息安全防范措施,以及使用这些防范措施过程中的一些经验和技巧,以提高整个系统的安全性和稳定性。     

Precession of the lunar core

Goldreich (Goldreich, P. [1967]. J. Geophys. Res. 72, 3135) showed that a lunar core of low viscosity would not precess with the mantle. We show that this is also the case for much of lunar history. But when the Moon was close to the Earth, the Moon’s core was forced to follow closely the precessing mantle, in that the rotation axis of the core remained nearly aligned with the symmetry axis of the mantle. The transition from locked to unlocked core precession occurred between 26.0 and 29.0 Earth radii, thus it is likely that the lunar core did not follow the mantle during the Cassini transition. Dwyer and Stevenson (Dwyer, C.A., Stevenson, D.J. [2005]. An Early Nutation-Driven Lunar Dynamo. AGU Fall Meeting Abstracts GP42A-06) suggested that the lunar dynamo needs mechanical stirring to power it. The stirring is caused by the lack of locked precession of the lunar core. So, we do not expect a lunar dynamo powered by mechanical stirring when the Moon was closer to the Earth than 26.0-29.0 Earth radii. A lunar dynamo powered by mechanical stirring might have been strongest near the Cassini transition.     

Vertical structure of Jupiter’s Oval BA before and after it reddened: What changed?

To constrain the properties of Oval BA before and after it reddened, we use Hubble methane band images from 1994 to 2009 to find that the distribution of upper tropospheric haze atop the oval and its progenitors remained unchanged, with reflectivity variations of less than 10% over this time span. We quantify measurement uncertainties and short-term fluctuations in velocity fields extracted from Cassini and Hubble data, and show that there were no significant changes in the horizontal velocity field of Oval BA in 2000, 2006, and 2009. Based on models of the oval’s dynamics, the static stability of the oval’s surroundings was also unchanged.The vertical extent of the oval did not change, based on the unchanged haze reflectivity and unchanged stratification. Published vortex models require Brunt-Väisälä frequencies of about 0.08 s⁻¹ at the base of the vortex, and we combine this value with a review of prior constraints on the vertically variable static stability in Jupiter’s troposphere to show that the vortex must extend down to the condensation level of water in supersolar abundance.The only observable change was an increase in short-wavelength optical absorption that appeared not at the core of the oval, but in a red annulus. The secondary circulation in the vortex keeps this red annulus warmer than the vortex core. Although the underlying cause of the color change cannot be proven, we explore the idea that the new chromophores in the red annulus may be related to a global or hemispheric temperature change.     

Families among high-inclination asteroids

We present a new classification of families identified among the population of high-inclination asteroids. We computed synthetic proper elements for a sample of 18,560 numbered and multi-opposition objects having sine of proper inclination greater than 0.295. We considered three zones at different heliocentric distances (inner, intermediate and outer region) and used the standard approach based on the Hierarchical Clustering Method (HCM) to identify families in each zone. In doing so, we used slightly different approach with respect to previously published methodologies, to achieve a more reliable and robust classification. We also used available SDSS color data to improve membership and identify likely family interlopers. We found a total of 38 families, as well as a significant number of clumps and clusters deserving further investigation.     

Modification of Jupiter’s stratosphere three weeks after the 2009 impact

Infrared spectroscopy sensitive to thermal emission from Jupiter’s stratosphere reveals effects persisting 23 days after the impact of a body in late July 2009. Measurements obtained on 2009 August 11 UT at the impact latitude of 56°S (planetocentric), using the Goddard Heterodyne Instrument for Planetary Wind and Composition mounted on the NASA Infrared Telescope Facility, reveal increased ethane abundance and the effects of aerosol opacity. An interval of reduced thermal continuum emission at 11.744 μm is measured ∼60-80° towards planetary east of the impact site, estimated to be at 305° longitude (System III). Retrieved stratospheric ethane mole fraction in the near vicinity of the impact site is enhanced by up to ∼60% relative to quiescent regions at this latitude. Thermal continuum emission at the impact site, and somewhat west of it, is significantly enhanced in the same spectra that retrieve enhanced ethane mole fraction. Assuming that the enhanced continuum brightness near the impact site results from thermalized aerosol debris blocking contribution from the continuum formed in the upper troposphere and indicating the local temperature, then continuum emission by a haze layer can be approximated by an opaque surface inserted at the 45-60 mbar pressure level in the stratosphere in an unperturbed thermal profile, setting an upper limit on the pressure and therefore a lower limit on the altitude of the top of the impact debris at this time. The reduced continuum brightness east of the impact site can be modeled by an opaque surface near the cold tropopause, which is consistent with a lower altitude of ejecta/impactor-formed opacity. The physical extent of the observed region of reduced continuum implies a minimum average velocity of 21 m/s transporting material prograde (planetary east) from the impact.