Precision IR and visible solar photometry     

H. Lin  J. R. Kuhn 《Solar physics》1992,141(1):1-26

A precision Solar Photometric Telescope (SPT) was constructed to study the large-scale thermal structure of the solar photosphere. This instrument does full-disk, broad-band (10 nm FWHM), two-color (500 and 650 nm) imaging of the solar photosphere. Data obtained by the SPT reveals network structures correlated with the supergranulation velocity field, and the CaK network of the chromosphere. Infrared array photometry extends these measurements to 1.6 and 2.2 micron. The observed correlation of the network brightness signal with the CaK network is positive at visible wavelengths. The correlation between the network at the opacity minimum (1.6 micron) and in the higher photosphere (2.2 micron) is positive also. The root-mean-square (r.m.s.) amplitude of the contrast at disk center is (2.34 ± 0.38) × 10^-3, (1.83 ± 0.51) × 10^-3, (1.02 ± 0.21) × 10^-3, and (1.11 ± 0.21) × 10^-3 for the green, red, H, and K band, respectively. It is consistent with a brightness temperature modulation of 2.9 K. The r.m.s. amplitude of the contrast of active region network shows a large increase toward the limb, and the quiet region network shows little center-to-limb variation (CLV). Power-spectrum analysis shows that the bright facular points in the active regions appear in the form of enhanced network.  相似文献   

P-wave velocities in rocks at high pressure and temperature and the constitution of the central California crust     

Wunan Lin  Chi-yuen Wang 《Geophysical Journal International》1980,61(2):379-400

Summary. Velocities of compressional waves are determined for central California rocks at pressures up to 0.7 GPa (7 kb) and temperatures up to 450°C. These data are used to interpret the seismic velocity structure of the crust in the California Coast Ranges. The seismic data on both sides of the San Andreas fault are consistent with the following model; besides some patches of surface sediments the upper 10—15 km of the crust on the northeast side consists predominantly of sedimentary and metasedimentary rocks of the Franciscan assemblage; the lower crust, of a thickness of 15—20 km, may be composed of gabbroic or other mafic rocks. Across the fault on the south-west side, the entire crustal section is probably a granitic complex similar to that exposed on the surface. The proposed model is shown to be consistent with the observed gravity anomaly.  相似文献   

Fast solar electrons,interplanetary plasma and km-wave type-III radio bursts observed from the IMP-6 spacecraft     

Hector Alvarez  Robert P. Lin  Samuel J. Bame 《Solar physics》1975,44(2):485-501

IMP-6 spacecraft observations of low frequency radio emission, fast electrons, and solar wind plasma are used to examine the dynamics of the fast electron streams which generate solar type-III radio bursts. Of twenty solar electron events observed between April, 1971 and August, 1972, four were found to be amenable to detailed analysis. Observations of the direction of arrival of the radio emission at different frequencies were combined with the solar wind density and velocity measurements at 1 AU to define an Archimedean spiral trajectory for the radio burst exciter. The propagation characteristics of the exciter and of the fast electrons observed at 1 AU were then conpared. We find that: (1) the fast electrons excite the radio emission at the second harmonic; (2) the total distance travelled by the electrons was between 30 and 70% longer than the length of the smooth spiral defined by the radio observations; (3) this additional distance travelled is the result of scattering of the electrons in the interplanetary medium; (4) the observations are consistent with negligible true energy loss by the fast electrons.  相似文献   

面向Internet的农业气象产量动态预报   总被引：2，自引：1，他引：1  

王石立  马玉平  刘文泉  林日暖  庄立伟 《气象》2004,30(4):42-45

针对信息时代Internet网上用户对产量预报动态查询的需求 ,探讨了面向Inter net的农业气象产量预报的解决方案。试验结果表明 ,由于作物生长发育和产量形成是一个光、温、水、土条件长期、综合作用 ,生物量长期累积的过程 ,因此利用积分回归方法 ,考虑全生育期光、温、水气象因子的综合影响 ,根据已出现的天气实况 ,在假定后期天气条件正常的情况下 ,有可能预测出未来产量的趋势。随着天气实况的逐一出现 ,后期的预报结果可望逐步接近实际值。统计检验和试报结果误差均在允许范围内。  相似文献   

Polycrystalline calcite to aragonite transformation kinetics: experiments in synthetic systems     

Shueh-Jung?Lin  Wuu-Liang?HuangEmail author 《Contributions to Mineralogy and Petrology》2004,147(5):604-614

The kinetics of the calcite to aragonite transformation have been investigated using synthetic polycrystalline calcite aggregates, with and without additional minerals present. The reaction progresses as a function of time were measured at four temperature/pressure conditions: (1) 550 °C/1.86 GPa; (2) 600 °C/2.11 GPa; (3) 650 °C/2.11 GPa, and (4) 700 °C/2.29 GPa. Experiments reveal that Mg-calcite and Fe-calcite transforms to aragonite at considerably slower rates than pure calcite, and that Sr-bearing calcite and calcite + quartz aggregates transform at significantly higher rates than pure calcite. The reaction progresses vs. time data for pure calcite were fitted to Cahns grain-boundary nucleation and interface-controlled growth model. Evidence for interface-controlled growth is provided by petrographic observations of grain boundaries. The activation energy for aragonite growth from the synthetic polycrystalline calcite determined in this study is significantly lower than that previously determined from a natural marble. The discrepancy in rates and activation energy may be attributed to the nature of grain boundaries, to deformational strain or the presence of impurities in the studied samples, and likely to uncertainties in experimental conditions. The results of this study imply that the variation of local petrologic conditions, in addition to temperature, pressure and grain size, may play an important role in determining the rates for the calcite to aragonite transformation in nature.Editorial responsibility: W. Schreyer  相似文献   

The mesoscale convection life cycle: Building block or prototype for large-scale tropical waves?   总被引：1，自引：0，他引：1  

Brian Mapes  Stefan Tulich  Jialin Lin  Paquita Zuidema 《Dynamics of Atmospheres and Oceans》2006,42(1-4):3

A cumulonimbus cloud may ascend and spawn its anvil cloud, precipitation, and downdrafts within an hour or so. This paper inquires why a similar progression of events (life cycle) is observed for tropical weather fluctuations with time scales of hours, days, and even weeks. Regressions using point data illustrate the characteristic unit of rain production: the mesoscale convective system (MCS), covering tens of kilometers and lasting several hours, with embedded convective rain cells. Meanwhile, averages over larger spatial areas indicate a self-similar progression from shallow to deep convection to stratiform anvils on many time scales.Synthetic data exercises indicate that simple superpositions of fixed-structure MCS life cycles (the Building Block hypothesis) cannot explain why longer period life cycles are similar. Rather, it appears that an MCS may be a small analogue or prototype of larger scale waves. Multiscale structure is hypothesized to occur via a Stretched Building Block conceptual model, in which the widths (durations) of zones of shallow, deep, and stratiform anvil clouds in MCSs are modulated by larger scale waves.Temperature (T) and humidity (q) data are examined and fed into an entraining plume model, in an attempt to elucidate their relative roles in these large-scale convection zone variations. T profile variations, with wavelengths shorter than troposphere depth, appear important for high-frequency ( 2–5-day period) convectively coupled waves, as density directly links convection (via buoyancy) and large-scale wave dynamics (via restoring force). Still, the associated q anomalies are several times greater than adiabatic, suggesting a strong amplification by shallow convective feedbacks. For lower frequency (intraseasonal) variability, q anomalies are considerably larger compared to T, and may be dominant.  相似文献   

Characterizing the severe turbulence environments associated with commercial aviation accidents. A real-time turbulence model (RTTM) designed for the operational prediction of hazardous aviation turbulence environments     

M. L. Kaplan  J. J. Charney  K. T. WaightIII  K. M. Lux  J. D. Cetola  A. W. Huffman  A. J. Riordan  S. D. Slusser  M. T. Kiefer  P. S. Suffern  Y.-L. Lin 《Meteorology and Atmospheric Physics》2006,94(1-4):235-270

Summary In this paper, we will focus on the real-time prediction of environments that are predisposed to producing moderate-severe (hazardous) aviation turbulence. We will describe the numerical model and its postprocessing system that is designed for said prediction of environments predisposed to severe aviation turbulence as well as presenting numerous examples of its utility. The purpose of this paper is to demonstrate that simple hydrostatic precursor circulations organize regions of preferred wave breaking and turbulence at the nonhydrostatic scales of motion. This will be demonstrated with a hydrostatic numerical modeling system, which can be run in real time on a very inexpensive university computer workstation employing simple forecast indices. The forecast system is designed to efficiently support forecasters who are directing research aircraft to measure the environment immediately surrounding turbulence. The numerical model is MASS version 5.13, which is integrated over three different grid matrices in real-time on a university workstation in support of NASA-Langley’s B-757 turbulence research flight missions. The model horizontal resolutions are 60, 30, and 15 km and the grids are centered over the region of operational NASA-Langley B-757 turbulence flight missions. The postprocessing system includes several turbulence-related products including four turbulence forecasting indices, winds, streamlines, turbulence kinetic energy, and Richardson numbers. Additionally there are convective products including precipitation, cloud height, cloud mass fluxes, lifted index, and K-index. Furthermore, soundings, sounding parameters, and Froude number plots are also provided. The horizontal cross section plot products are provided from 16,000–46,000 feet in 2,000 feet intervals. Products are available every three hours at the 60 and 30 km grid interval and every 1.5 hours at the 15 km grid interval. The model is initialized from the NWS ETA analyses and integrated two times a day.  相似文献   

抚顺市市区地质灾害遥感调查研究   总被引：1，自引：0，他引：1       下载免费PDF全文

马小计  杨自安邹 林张普斌张建国 《中国地质》2006,33(5):1167-1173

抚顺市是中国重要的大型煤炭工业基地之一。由于长期的采掘施工,其采矿场和采矿坑不断扩大加深,导致了矿区及其周边地带地面不稳定性的不断加剧,且已发生了局部的地面沉降等地质灾害,给人们的生产和生活带来了直接的威胁,并严重地影响着该地区社会经济的可持续发展。本研究工作采用遥感技术手段,快速地查明该地区现有的地质灾害类型、数量及其表现形式,以及地质灾害与断裂构造的相互关系,从而为在该地区进行地质灾害防治工作提供准确可靠的依据,取得了良好的应用效果。  相似文献   

RTK技术在高速公路土地登记测量中的应用     

彭琳  詹长根  胡凯 《测绘通报》2006,(3):50-51

首先讨论RTK在高速公路土地登记测量中的优越性,根据两个实例,比较RTK与全站仪、不同的RTK结果之间的差异,RTK与全站仪的点位互差为3cm,不同方式的RTK结果的点位互差也为3cm。  相似文献   

基于生态事件序列的时态关联规则挖掘   总被引：1，自引：0，他引：1  

翟亮  李霖  姜文亮  陈媛媛 《测绘科学》2006,31(3):41-44

本文分析了时态关联规则挖掘的相关定义,介绍了强时态关联规则挖掘的步骤,设计并实现了基于时间约束的T-Apriori算法。提出了生态事件和生态时间序列的概念,以我国南海大亚湾海域的赤潮现象为例,研究了基于生态事件序列的时态关联规则挖掘问题。  相似文献