Evidence for solar neutrino flux variability and its implications     

D.O. Caldwell  P.A. Sturrock 《Astroparticle Physics》2005,23(6):543-556

Although KamLAND apparently rules out resonant-spin-flavor-precession (RSFP) as an explanation of the solar neutrino deficit, the solar neutrino fluxes in the Cl and Ga experiments appear to vary with solar rotation. Added to this evidence, summarized here, a power spectrum analysis of the Super-Kamiokande data reveals significant variation in the flux matching a dominant rotation rate observed in the solar magnetic field in the same time period. Three frequency peaks, all related to this rotation rate, can be explained quantitatively. A Super-Kamiokande paper reported no time variation of the flux, but showed the same peaks, there interpreted as statistically insignificant, due to an inappropriate analysis. This modulation is small (7%) in the Super-Kamiokande energy region (and below the sensitivity of the Super-Kamiokande analysis) and is consistent with RSFP as a subdominant neutrino process in the convection zone. The data display effects that correspond to solar-cycle changes in the magnetic field, typical of the convection zone. This subdominant process requires new physics: a large neutrino transition magnetic moment and a light sterile neutrino, since an effect of this amplitude occurring in the convection zone cannot be achieved with the three known neutrinos. It does, however, resolve current problems in providing fits to all experimental estimates of the mean neutrino flux, and is compatible with the extensive evidence for solar neutrino flux variability.  相似文献   

X-RAY Periodicity in AGN     

Karen M. Leighly 《Astrophysics and Space Science》2005,300(1-3):137-142

Significant (marginal) detections of periodic signals have been recently reported in 3 (4) Active Galactic Nuclei. Three of the detections were obtained from long EUVE light curves of moderate-luminosity Seyfert galaxies; the fourth was discovered in Chandra data from the low-luminosity Seyfert 1 galaxy NGC 4395. When compared with Cyg X-1, I find that the period is related to the luminosity as P∝ L^2/3 rather than the expected one-to-one relationship. This result might be explained if the QPO is associated with the inner edge of the optically thick accretion disk, and the inner-edge radius depends on the source luminosity (or black hole mass). A discussion of uncertainties in the period detection methodology is also discussed.  相似文献   

Infiltration characteristics of a complex lateritic soil profile     

J. K. Ruprecht  N. J. Schofield 《水文研究》1993,7(1):87-97

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BOOK REVIEWS     

《The Professional geographer》1986,38(1):105-130

Book Reviewed in this article: Unfairly Structured Cities . Blair Badcock Religion and Rural Revolt . Janos M. Bak and Gerhard Benecke The Industrial Geography of Canada . Anthony Blackbourn and Robert G. Putnam The Cuban-American Experience, Culture, Images, and Perspectives. Thomas D. Boswell and James R. Curtis Quaternary Paleoclimatology . R. S. Bradley Development and Crisis in Brazil, 1930–1983 . Luiz Bresser Pereiras Centres of Origin in Biogeography . John C. Briggs Analytical Urban Geography . Martin Cadwallader Geomorphology . Richard J. Chorley , Stanley A. Schumm, and David E. Sugden South Africa: The Impact of Past Geographies . A. J. Christopher The Geography of Underdevelopment. A Critical Survey . D. K. Forbes Health Care in Developing Countries . Wilbert M. Gesler Place to Grow Old: The Meaning of Environment in Old Age . Stephen M. Golant The Emerging Marine Economy of the Pacific . Chennat Gopalakrishnan An Introduction to Agricultural Geography . David B. Grigg The Soviet Union: A Geographical Study . G. Melvyn Howe Geographical Aspects of Health: Essays in Honour of Andrew Learmonth . N. D. Mc Glashan and J. R. Blunden Physical Geography: A Landscape Appreciation . Tom L. Mc Knight Mountain Experience. The Psychology and Sociology of Adventure. Richard G. Mitchell Jr . Systematic and Regional Biogeography. Stanley A. Morain The Economic Transformation of American Cities. T. J. Noyelle and T. M. Stanback , Jr . Normal Accidents: Living With High-Risk Technologies. Charles Perrow Vanishing Farmland: A Legal Solution for the States. Sarah E. Redfield Applied Methods of Regional Analysis: The Spatial Dimensions of Development Policy. Dennis A. Rondinelli Urbanization in Romania. A Geography of Social and Economic Change Since Independence. Per Ronnas Statistical Techniques in Geographical Analysis. Gareth Shaw and Dennis Wheeler The Granite Garden: Urban Nature and Human Design. Anne Whiston Spirn Political Geography: Recent Advances and Future Directions. Peter Taylor and John House Geographia y Medio Ambiente. Manuel Valenzuela -Rubío Nãgara and Commandery: Origins of the Southeast Asian Urban Traditions. Paul Wheatley The Common Fisheries Policy of the European Community. Mark Wise Geography and Gender. Women and Geography Study Group of the IBG Technological Hazards. D. J. Zeigler , J. H. Johnson , S. D. Brunn  相似文献   

GRAIN PRODUCTION AND CLIMATIC VARIATION IN TAIHU LAKE BASIN     

沈小英  陈家其 《中国地理科学(英文版)》1993,3(2):173-178

Before the end of the Ming Dynasty to the early of the Qing Dynasty, climate was warm, and heat energy was plentiful, so double-cropping of rice in Taihu Lake basin could grow without any protection. Later the global climate entered the Little Ice Age, the double-cropping of rice was extirpated nearly, grain output decreased heavily. After the Little Ice Age, although, the global climate got warm, sometimes, the thermal condition was enough for two crops no three crops one year throughout the period. So both the area and output of of double-cropping of rice was fluctuated with variation of cold/ warm. The condition of heat energy, with the movement of climatic zone, becomes a sensitive factor effecting grain production. Recently, as CO2concentra-tion in atmosphere is increasing, climate is getting warm. With the comprehensive effect of such warming and natural cooling trend, the climate in Taihu Lake basin shows the following trend: warm in winter, cooling in summer, decreasing of annual accumulated tem  相似文献   

基于AEZ模型的产量动态预报研究     

徐延红 《气象与环境科学》2018,41(2):20-24

利用洛阳地区1981-2014年夏玉米产量资料、9个气象站点的逐日观测资料、农田0-50 cm土壤墒情资料,结合夏玉米生物学特性,采用农业生态区域法(AEZ模型),计算了夏玉米不同生长阶段的气候生产潜力,通过气候生产潜力与夏玉米产量的相关关系,建立以旬为尺度的夏玉米产量动态预报模型,并进行历史回代和试报检验。结果表明:气候生产潜力与夏玉米单产增减率呈显著正相关,气候生产潜力可以客观地反映夏玉米单产水平及其动态变化。构建的产量动态预报模型对1981-2010年单产历史回代检验的准确率为88.3%~90.7%,单产丰歉趋势回代检验准确率为65.5%~75.9%;对2011-2014年模型准确性试报检验,单产预报准确率为82.7%~87.5%,趋势预报准确率为50.0%~100.0%。  相似文献   

ENSO对中国南方降水低频变率的可能影响          下载免费PDF全文

张文君  雷徐奔  耿新  祁莉 《大气科学学报》2018,41(5):585-595

利用1979—2012年Hadley中心海表温度、中国2 474个台站逐日降水和NCEP/NCAR全球再分析资料,分析了不同类型ENSO事件秋冬季和次年春季中国南方地区10~30 d降水低频变率的变化特征。结果表明,中国南方地区10~30 d降水低频变率对不同类型ENSO事件的响应存在显著的季节差异。EP型El Ni1o的冬季和次年春季,低频降水变率显著增强; CP型El Ni1o秋冬季低频降水强度呈现相反的异常,秋季低频降水偏弱,而冬季则偏强; La Ni1a事件期间中国南方低频降水变率的变化较小且不稳定。进一步分析发现,ENSO对南方地区10~30 d低频降水变率的影响与西北太平洋地区季节平均大气环流背景场对ENSO的响应密切相关。相比正常年份,EP型El Ni1o冬春季菲律宾反气旋性异常环流的强度较强且范围较大,其西侧的异常西南风向中国南方地区输送了大量水汽,从而有利于低频降水的增强; CP型El Ni1o年秋季西北太平洋表现为气旋性环流异常,抑制了热带水汽向东亚大陆的输送,而冬季却产生了与EP型El Ni1o年类似的异常反气旋环流,只是强度有所减弱,因此中国南方地区低频降水强度在秋冬季呈相反异常。La Ni1a年菲律宾附近虽然存在气旋性环流异常,但强度较弱,因而我国南方地区低频降水变率的响应也较弱。  相似文献   

Interannual Variations in Synoptic-Scale Disturbances over the Western North Pacific     

Xingyan ZHOU  Riyu LU  Guanghua CHEN  Liang WU 《大气科学进展》2018,35(5):507-517

The present study investigates the interannual variation of June–November synoptic disturbance activity over the western North Pacific(WNP) and its relationship with large-scale circulation for the period 1958–2014. Two leading modes of eddy kinetic energy for the disturbance variability over the WNP are obtained by EOF analysis, characterized by anomalous eddy kinetic energy over the subtropical WNP and around the Philippines, respectively. These modes explain a large portion of the interannual variance of synoptic disturbance activity over the WNP. Both are associated with lower-level cyclonic anomalies, but with different locations: over the subtropical WNP for the first mode and over the South China Sea for the second mode. Considering the impact of ENSO on synoptic disturbance activity over the WNP, we repeat the analyses after removing the effect of ENSO, which is simply defined as the components linearly regressed onto the Ni o3.4 index, and find similar results, suggesting that the leading modes and their relationships with large-scale circulation exist without SST effects.Further analyses suggest that the meridional shear of zonal winds caused by cyclonic anomalies is crucial for maintaining the leading modes through barotropic conversion.  相似文献   

The 30–60-day Intraseasonal Variability of Sea Surface Temperature in the South China Sea during May–September     

Jiangyu MAO  Ming WANG 《大气科学进展》2018,35(5):550-566

This study investigates the structure and propagation of intraseasonal sea surface temperature(SST) variability in the South China Sea(SCS) on the 30–60-day timescale during boreal summer(May–September). TRMM-based SST, GODAS oceanic reanalysis and ERA-Interim atmospheric reanalysis datasets from 1998 to 2013 are used to examine quantitatively the atmospheric thermodynamic and oceanic dynamic mechanisms responsible for its formation. Power spectra show that the 30–60-day SST variability is predominant, accounting for 60% of the variance of the 10–90-day variability over most of the SCS. Composite analyses demonstrate that the 30–60-day SST variability is characterized by the alternate occurrence of basin-wide positive and negative SST anomalies in the SCS, with positive(negative) SST anomalies accompanied by anomalous northeasterlies(southwesterlies). The transition and expansion of SST anomalies are driven by the monsoonal trough–ridge seesaw pattern that migrates northward from the equator to the northern SCS. Quantitative diagnosis of the composite mixed-layer heat budgets shows that, within a strong 30–60-day cycle, the atmospheric thermal forcing is indeed a dominant factor, with the mixed-layer net heat flux(MNHF) contributing around 60% of the total SST tendency, while vertical entrainment contributes more than 30%. However, the entrainment-induced SST tendency is sometimes as large as the MNHF-induced component, implying that ocean processes are sometimes as important as surface fluxes in generating the30–60-day SST variability in the SCS.  相似文献   

任意时段累年气候数据统计流程优化及应用     

刘尉  吴门新  庄立伟 《气象科技》2018,46(2):250-256

任意时段累年气候数据的统计是气象部门一项常规实时(准实时)业务,需要相应业务系统的支撑。为了提高该系列数据的统计检索效率,本文对获取该数据的统计流程进行了优化,提出了优化后的原始数据逻辑分解流程,并以关系型数据库Oracle为例,利用广东省86个国家气象观测站近65年,及2313个区域自动气象站近10年逐日气象数据,进行了任意时段累年气候数据统计流程优化前后效率的对比。结果显示:基于优化前的流程,随着任意时段日期跨度的增长,数据统计效率逐步降低;而基于优化后的流程,无论任意时段起止日期的跨度大小,数据统计均可以保持很高的效率。本文将优化后的统计流程应用于广东省农业气象业务系统(AGROS)对应的功能模块,对提高系统效率、优化用户体验起到了很大作用,并进一步推动了该系统在广东全省的推广应用。对于全国各省区乃至国家级气象部门业务系统相关模块的开发也有参考价值。  相似文献