Deglaciation effects on the rotation of the Earth

Summary. The viscoelastic response of the Earth to the mass displacements caused by late Pleistocene deglaciation and concomitant sea level changes is shown to be capable of producing the secular motion of the Earth's rotation pole as deduced from astronomical observations. The calculations for a viscoelastic Earth yield a secular motion in the direction of 72° W meridian which is in excellent agreement with observed values. The average Newtonian viscosity and the relaxation time obtained from polar motion data are about (1.1 ± 0.6)10²³ poise (P) and 10⁴ (1 ± 0.5) yr. The non-tidal secular acceleration of the Earth can also be attributed to the viscoelastic response to deglaciation and results in an independent viscosity estimate of 1.6 × 10²³ P with upper and lower limits of 1.1 × 10²³ and 2.8 × 10²³ P. These values are in agreement with those based on the polar drift analysis and indicate an average mantle viscosity of 1–2 × 10²³ P.     

Detection of the 11 yr sunspot cycle signal in Earth rotation

Summary. A two-channel MESA or maximum entropy spectrum analysis (Morf et al. 1978) between Δ T °= ET – UT (Morrison 1973) and sunspot numbers spanning 1832–1975 yields the following results over a bandwidth 2–20yr: (1) The spectra of Δ T ° and sunspot numbers are both dominated by a narrow band signal at 11.0 yr; (2) On average the coherency over the continuum is 0.14 while at 11.0yr it peaks at 0.83; (3) The 11-yr sunspot cycle signal in length of day (lod) has an amplitude of 0.16 ms, and in time lags that in sunspot numbers by 3.4yr. Estimates obtained from segmenting the series yield extremal values which grossly bound the above estimates: The narrow band signal has period range (10.5–11.4yr) coherency (0.8–1.0), amplitude (0.06–0.31 ms), and time lag (3.0–3.Syr). In addition, a two channel analysis of sunspot numbers with a new Δ T ⁿ series from 1861–1978 (Morrison 1979) and an earlier segment of Δ T °, as well as a single-channel analysis of Δ T ° and Δ T ⁿ individually, further support the conclusion that the solar sunspot cycle in Earth rotation has been detected. These experimental results have implications in astronomy, solar physics, meteorology and climatology.     

近30年来中国地理学及相关学科期刊的发展

1978年以来的30年间,中国地理学及相关学科期刊取得了飞速发展.地理学及相关学科期刊种类增加,覆盖了自然地理、经济地理和地球信息科学等各专业;主办地理学及相关学科期刊的机构包括中国科学院所属研究所、省级科学院所属研究所和高等院校;地理学及相关学科期刊的版面迅速增加.与此同时,地理学及相关学科期刊的学术质量和国际影响力在不断提高,获得了国家期刊奖和各部委的多项奖励,英文版地理学及相关学科期刊被SCI等国际著名检索机构和数据库收录.     

Oceanic excitation of daily to seasonal signals in Earth rotation: results from a constant-density numerical model

Velocity and mass fields from a constant-density, near-global ocean model, driven with observed twice-daily surface wind stresses and atmospheric pressures for the period October 1992-September 1993, are used to calculate oceanic excitation functions for the length of day (LOD) and for polar motion (PM), and results are analysed as a function of the frequency band. Variable currents and mass redistributions are both important in determining oceanic excitation functions. For bands with periods longer than one month, wind-driven variability is the primary cause of oceanic excitation signals. At higher frequency bands, larger deviations from the inverted barometer response occur, and pressure-driven signals contribute more significantly to the variance in the excitation functions. Oceanic LOD excitation is generally small compared to that of the atmosphere, except for the 2-10 day band. At these scales, adding oceanic to atmospheric excitation series does not lead to better agreement with the observed LOD, although this result may be related to data quality issues. With regard to the excitation of PM, the ocean is in general as important as the atmosphere at most time scales. Combined oceanic and atmospheric excitation series compare visibly better with geodetic series than do atmospheric series alone, pointing to the ocean as a source of measurable signals in PM.     

1978-2015年喀喇昆仑山克勒青河流域冰川变化的遥感监测

本文采用1978、1991、2001和2015年的Landsat MSS、TM、ETM+和OLI遥感影像,通过遥感图像计算机辅助分类和目视解译等方法提取冰川边界,分析喀喇昆仑山克勒青河流域冰川在1978-2015年间的进退变化。结果表明：1978-2015年间研究区冰川面积由1821.70 km2减少至1675.92 km2,减少145.78 km2,占1978年冰川总面积的8.00%;冰川消融率较低,在气候变暖的背景下反而呈现出退缩速率由快变慢的趋势。研究区东南向冰川退缩率明显高于西北向,冰川退缩率随冰川规模的增大而减小。研究区内有27处冰川在1978-2015年间发生过特殊的前进现象,面积与长度显著增加。其中,木斯塔冰川西侧冰川末端在1996-1998年间前进速度为904 m/a,乔戈里冰川东侧冰川末端在2007-2009年间前进速度为446 m/a,5Y654D0097冰川末端在1978-1990年间前进速度为238 m/a,初步判定这三条冰川为跃动冰川。以10 a为滞后期分析研究区周边气象站点资料发现：研究区气温持续升高,降水量以1981年为分界点呈现“先减后增”趋势是冰川退缩速率减慢的原因之一;此外,亚大陆型冰川性质、巨大山势条件和高山冷储作用,也可能是冰川退缩幅度较小的原因。     

1978-2006年甘肃产业结构演进分析

以1978-2006年统计数据为基础,采用产业经济学、计量经济学和统计学的相关方法,对甘肃省改革开放以来的产业结构演进进行了定量分析,对其与同期全国产业结构演进进行了比较。研究结果表明,1978年以来,甘肃与全国产业结构演进存在差异,主要表现为:甘肃第二产业比重明显偏低,第三产业比重偏高;甘肃产业产值比重与就业比重不均衡度明显高于全国,近年有扩大趋势;甘肃的产业结构转换速度缓慢,且主要依赖第三产业的推动,转换方向不尽合理;甘肃经济增长结构效应在减弱,增长结构中夕阳产业比重高,比较优势产业竞争力有所提高。     

1978-2015年东莞豪华酒店时空演变与制度重构

东莞豪华酒店作为社会文化地理现象备受学术界与理论界的关注。本文采用深度访谈和文本分析方法,援引制度与空间的相关理论,探讨东莞豪华酒店时空演变背后的制度根源,试图解释在国家与地方的制度环境下,显性正式与非正式制度、隐性正式与非正式制度是如何成为一种内在的力量影响东莞豪华酒店的时空演变。研究发现：① 在地方尺度下,东莞豪华酒店经历了酝酿期（1978-1993年）、投资和投机探索期（1994-1999年）、腾飞发展和扭曲变异糅合期（2000-2004年）3个阶段,分别呈现出制度推动空间发展、制度与空间磨合、空间反作用于制度重构3个不同的特征;② 在区域尺度下,东莞豪华酒店迎来平行和稳步建构期（2005-2012年）,体现出权力空间从东莞流向外围。空间变化暗示权力关系的变化,表明东莞豪华酒店从深层次影响制度重构已经迫在眉睫;③ 在国家尺度下,东莞豪华酒店进入自上而下的整顿和转型重构期（2013-2015年）,显性正式制度迫使空间行为选择进入理性阶段。研究完善了制度与空间关系的理论,提出空间的发展最终受制于显性正式制度,中间经历了空间尺度的转换,经历了各种显性与隐性、正式与非正式制度的博弈,最终回归到显性正式制度。空间演变是一个被制度化的过程,制度在空间权力关系中不断完善与变迁才能形成符合空间景观与空间形态规律的制度体系。     

1978-2016年中国农业生态效率时空演变及趋势预测

基于1978-2016年中国各省市面板数据,采用超效率SBM模型测算省际农业生态效率,在时间序列分析和空间相关性分析的基础上,构建传统和空间马尔可夫概率转移矩阵,探讨中国农业生态效率的时空动态演变特征,并预测其长期演变的趋势。研究发现：① 中国农业生态效率呈现出在波动中稳定上升的“双峰”分布特征,且波峰高度的差距在缩小,但整体仍处于较低水平,农业生态效率仍存在较大提升空间,东部地区农业生态效率提升较中西部地区更加显著;② 中国农业生态效率整体上向高水平方向转移的趋势显著,但农业生态效率的演变具有维持原有状态的稳定性,且较难实现跨越式转移。地理空间格局在农业生态效率时空演变过程中发挥着重要作用,空间集聚特性显著,农业生态效率较高的省市具有正向的溢出效应,而农业生态效率较低的省市具有负的溢出效应,从而在空间格局上逐渐形成“高高集聚、低低集聚、高辐射低、低抑制高”的“俱乐部收敛”现象;③ 从长期演变的趋势预测来看,多数省市农业生态效率逐渐向上转移为较高水平,并逐渐演变为由低到高渐次递增的格局,在农业生态效率较低的地理背景下,其长期演变的稳定状态表现为偏“单峰”分布,而在农业生态效率较高的地理背景下,其长期演变为较高水平集聚的偏“双峰”分布。最后,分析当前研究需要改进的方向,并提出控制农业污染排放量、地区间农业生态政策联动、加强地区间农业生态合作交流与借鉴等能够有效提升中国农业生态效率及缩小省市间差距。     

2003-2017年植被变化对全球陆面蒸散发的影响

蒸散发是陆面水循环的关键环节和过程,是研究水循环对人类活动和气候变化响应的关键要素.过去十几年,全球下垫面的植被变化剧烈,但如何影响全球陆面蒸散发仍未得到清晰的揭示.本文采用500 m分辨率MODIS数据驱动PML-V2模型,定量解析了 2003-2017年植被变化对全球陆面蒸散发的影响.结果显示:在全球尺度上,植被变...     

Regional population trends in the city of Moscow during the 1979-1989 intercensal period

"This article investigates regional population trends in the city of Moscow during the intercensal period of 1979-1989. Results indicate that the Outer Zone grew more rapidly than the Inner Zone, which experienced population decline overall. As a result, the population of Moscow continued to shift to the Outer Zone. Although the Inner Zone still had a higher population density, the density gradient between the zones had flattened appreciably. Regional population growth rates were strongly and positively related to changes in housing space."     

1978~2014年中国城市化与经济增长关系研究——基于省域面板数据

利用省域面板数据进行单位根检验和协整检验,对1978~2014年中国(不包括港澳台地区)经济增长和城市化的关系,以及不同省域经济增长与城市化作用程度进行研究,同时运用Mann-Kendall方法将中国城市化增长分成1978~1995年和1996~2014年两个阶段,并对不同阶段中国省域经济增长和城市化的相互作用关系进行研究,结果表明：① 1978~2014年中国经济增长对城市化具有促进作用,从各省域的相互作用程度来看呈现中东部较低,西南和东北部较高的区域格局,同时此阶段城市化对于经济增长的作用并没有得到证实。② 1978~1995年中国城市化和经济增长之间的相互作用关系没有得到证实。③ 1996~2014年中国城市化与经济增长相互促进,从各省域城市化对经济增长的作用强度来看呈现出中东部低,而周边内陆省区高的区域格局,而经济增长对城市化作用的区域格局与之相反。     

1978年以来中国旅游地理学的检讨与反思

自1978年以来,中国旅游地理学得到了较快发展,然而存在着理论和方法的研究薄弱、研究内容范围较为狭窄、重复工作较多且整体水平提高缓慢等问题.从以下角度反思中国旅游地理学25年的发展和问题,对这一学科将来的进步不无裨益.(1)学术研究与应用实践之间的关系.20多年来,中国旅游地理学界始终以服务于国民经济为主攻方向,旅游地理学的应用价值被无限夸大,反过来制约了其他方面的研究拓展和深入.实际上,旅游地理学研究,绝不只是一个经济问题,它也需要关注社会公平、环境伦理.(2)研究的观念与目标.中国旅游地理学有必要树立新的研究观念,认清自身的研究状态.没有反省、没有自我的怀疑、没有批判和创新的研究,其研究贡献是非常有限的.(3)研究的方法与成果.实证研究在过去25年的中国旅游地理研究中是一种常见方法,然而,不能把利用数学和量化的方法来进行研究看作解决问题的唯一途径,况且低水平的实证研究有时会成为无价值的案例堆积,浪费研究资源和研究者的时间与精力.对研究成果应该有新的认识:该成果的真正价值是什么?国内外类似成果的差异(而不仅仅是差距)在哪里?如何确认和尊重该成果的知识产权?(4)应对危机与挑战.将旅游地理学者的学术贡献与应用性工作例如规划混淆起来评价的做法是不恰当的,因为这类评价将使旅游地理学者的"社会价值"掩盖或超越其"学术价值",并深刻地影响着他们在研究与应用上的精力分配,这就可能使学科本身面临严重危机.     

Comprehensive analysis of changes to catchment slope properties in the high-sediment region of the Loess Plateau, 1978-2010

To control soil erosion and restore the degraded environment in the Loess Plateau, a large number of measures related to soil and water conservation have been employed that have profoundly affected catchment properties. This study constructed three indicators to characterize changes to the catchment slope, proposed both a method for a regression analysis of adjacent images and a sequence model, and applied multisource remotely sensed images and GIS spatial clustering analysis technologies to extract thematic information and comprehensively analyze the catchment change characteristics. The results indicate that the catchment slope properties changed significantly. At catchment scale, the average values of ARC, DVC and ART were 6.43%, 25.57% and 4.30%, respectively. There were six clustering types of catchment slope property changes. The maximum and minimum of the average similarities of the clustering types were 0.992 and 0.935. Each slope control measures had a distinct effect on catchment slope; the dominating factor of each clustering type was identified as: Type 1: D-VC, Type 2: D-VCLU, Type 3: D-LUVC, Type 4: D-TAVC, Type 5: D-TAC and Type 6: D-MFC. Type 5 and Type 1 covered the largest areas, respectively occupying 37.28% and 31.01%. Catchment slope property changes also had distinct types that depended on their geomorphological conditions. These findings provide a useful basis from which to further study catchment slope hydrological and soil erosion processes.     

Social-demographic development of Vologda Oblast during the intercensal period 1970-79

"Demographic trends in Vologda Oblast are analyzed on the basis of 1979 census results as a case study of an oblast involved in the [development] program for the Nonchernozem Zone of the RSFSR. The trend in the 1970-79 intercensal period was for continuing growth of urban population, especially in the two major urban centers of Vologda and the iron and steel city of Cherepovets, and depopulation of rural areas. The age-sex structure is distinguished by a strong aging trend and sex imbalance, especially in rural areas. Despite the proclaimed aim of fostering abandonment of tiny rural places (with 25 residents or less), the number of places in that size class actually increased during the intercensal period (from 40% of all rural places in 1970 to 52 percent in 1979)."