对月日潮汐摩擦耗散的估计

月日潮汐摩擦和地球惯量矩变化是日长长期变化的主要原因．在本文中，利用最新的地球物理和古生物钟数据，对过去15亿年以来的月日潮汐摩擦、地球惯量矩变化和日长长期变化等作了数值对比研究．由此得到二个重要结论：一是仅利用地球的自转形变不能解释J2的变化，这说明地球的重力分异现象至今仍存在着；其二是在几亿年前的潮汐摩擦比现在大得多，若取潮汐耗散与距离的立方成反比时，理论结果与由古生物钟得到的回归年日数和朔望月日数数据较为符合。     

CLIMATIC TREND INDICATED BY VARIATIONS OF GLACIERS AND LAKES IN THE TIANSHAN MOUNTAINS

ＣＬＩＭＡＴＩＣＴＲＥＮＤＩＮＤＩＣＡＴＥＤＢＹＶＡＲＩＡＴＩＯＮＳＯＦＧＬＡＣＩＥＲＳＡＮＤＬＡＫＥＳＩＮＴＨＥＴＩＡＮＳＨＡＮＭＯＵＮＴＡＩＮＳ￥ＨｕＲｕｊｉ；ＹａｎｇＣｈｕａｎｄｅ；ＭａＨｏｎｇ；ＪｉａｎｇＦｅｎｇｑｉｎｇ（ＸｉｎｊｉａｎｇＩｎ...     

Researches in China on the Effects of Tides on the Earth Rotation

In this paper the tidal phenomena on the Earth are concisely specified, including solid tides, ocean tides and atmospheric tides due to the luni-solar tide-generating force, and the Earth pole tide due to the motion of the Earth's rotation axis (polar motion); as well as their effects on the Earth rotation. The outcomes of scientific researches of Chinese astronomers on these topics are described in some detail. These researches deal with the mechanisms responsible for tidal effects on the earth rotation, and on the measurements of the Earth rotation parameters. Finally, the effects discovered by Chinese researchers on the measurements of the period and change in period of pulsars are discussed. These effects are very small in magnitude but not negligible.     

Runoff responses to afforestation in a watershed of the Loess Plateau,China

Afforestation has been suggested as a means of improving soil and water conservation in north‐western China, especially on the Loess Plateau. Understanding of the hydrological responses to afforestation will help us develop sustainable watershed management strategies. A study was conducted during the period of 1956 to 1980 to evaluate runoff responses to afforestation in a watershed on the Loess Plateau with an area of 1·15 km², using a paired watershed approach. Deciduous trees, including locust (locusta L.), apricot (praecox L.) and elm (ulmus L.), were planted on about 80% of a treated watershed, while a natural grassland watershed remained unchanged. It was estimated that cumulative runoff yield in the treated watershed was reduced by 32% as a result of afforestation. A significant trend was also observed that shows annual runoff reduction increases with the age of the trees planted. Reduction in monthly runoff occurred mainly from June to September, which was ascribed to greater rainfall and utilization by trees during this period. Afforestation also resulted in reduction in the volume and peak flow of storm runoff events in the treated watershed with greater reduction in peak flow. Copyright © 2003 John Wiley & Sons, Ltd.     

The hydrological influence of black locust plantations in the loess area of northwest China

Black locust (Robina pseudoacacia) has become one of the most important shelter species in the loess area of northwest China. This paper summarizes recent research concerning its hydrological influence, including canopy interception, litter absorption capacity, its effect on rainfall kinetic energy, infiltration rates, surface runoff, soil moisture, and evapotranspiration, and its role in soil conservation. Several predictive models are listed. on the basis of existing results, optimum characteristics for an effective plantation are defined, and problems requiring further research are identified.     

Wavelet analysis of inter‐annual variability in the runoff regimes of glacial and nival stream catchments,Bow Lake,Alberta

Continuous wavelet analyses of hourly time series of air temperature, stream discharge, and precipitation are used to compare the seasonal and inter‐annual variability in hydrological regimes of the two principal streams feeding Bow Lake, Banff National Park, Alberta: the glacial stream draining the Wapta Icefields, and the snowmelt‐fed Bow River. The goal is to understand how water sources and flow routing differ between the two catchments. Wavelet spectra and cross‐wavelet spectra were determined for air temperature and discharge from the two streams for summers (June–September) 1997–2000, and for rainfall and discharge for the summers of 1999 and 2000. The diurnal signal of the glacial runoff was orders of magnitude higher in 1998 than in other years, indicating that significant ice exposure and the development of channelized glacial drainage occurred as a result of the 1997–98 El Niño conditions. Early retreat of the snowpack in 1997 and 1998 led to a significant summer‐long input of melt runoff from a small area of ice cover in the Bow River catchment; but such inputs were not apparent in 1999 and 2000, when snow cover was more extensive. Rainfall had a stronger influence on runoff and followed quicker flow paths in the Bow River catchment than in the glacial catchment. Snowpack thickness and catchment size were the primary controls on the phase relationship between temperature and discharge at diurnal time scales. Wavelet analysis is a fast and effective means to characterize runoff, temperature, and precipitation regimes and their interrelationships and inter‐annual variability. The technique is effective at identifying inter‐annual and seasonal changes in the relative contributions of different water sources to runoff, and changes in the time required for routing of diurnal meltwater pulses through a catchment. However, it is less effective at identifying changes/differences in the type of the flow routing (e.g. overland flow versus through flow) between or within catchments. Copyright © 2003 John Wiley & Sons, Ltd.     

ANALYSIS ON THE SPATIAL DISTRIBUTION VARIATION CHARACTERISTIC OF URBAN HEAT ENVIRONMENTAL QUALITY AND ITS MECHANISM——A Case Study of Hangzhou City

Urban heat environmental quality(UHEQ) is affected by the interacting of weather condition and underlying surface framework of urban area .In the last two decades,many researchers from domestic and overseas have studied many problems at the aspect of urban heat environment such as urban heat islands ,urban air temperature and their rela-tion with urban land cover,city population,air pollution etc,In the recent years,Hangzhou,acting as a center city of Zhejiang Province in China,its urbanization quantum and quantity have both changed greatly,in particular ,representing as business affairs building,resident real property and all kins of specialty market having arisen in built-up zone,Based on Landsat TM images data in 1991 and 1999,urban underlying surface temperature value and Normalized Difference Vegetation Index (NDVI) were calculated using image interpreting and supervised classification technique by remote sensing software ERDAS image 8.4,The relation model between urban underlying surface temperature (UUST )and urban air temperature was setup according to the certain correlation patten .Reference to the relational standard of assessing human comfort and other meteorology data of Hangzhou City in summer,the spatial distribution characteristic and the spatial varia-tion degree of human comfort of heat environmental quality are estimated and mapped on a middle scale,that is ,in six districts of Hangzhou City .Then the paper reveals the main characteristic of spatial variation from 1991 to 1999.Lastly,the change mechanism is analyzed and discussed from the viewpoint of city planning,construction and environmental protec-tion.     

The importance of oxygen isotope provenance in relation to solute content of bulk meltwaters at Imersuaq Glacier,West Greenland

Stable oxygen isotope analysis and measurement of several dissolved cations and anions of bulk meltwater samples have provided information about the hydrochemical environment of the glacial hydrological system at Imersuaq Glacier, an outlet tongue from the Greenland ice‐sheet, West Greenland. The samples were collected at frequent intervals during the period 20–28 July 2000 in a small (<20 L s^?1) englacial meltwater outlet at the glacier margin. The results document the following findings: (i) a marked diurnal variation of δ¹⁸O is related to the composition of oxygen isotope provenances, mainly near‐marginal local superimposed ice and basal up‐sheared ice further up‐glacier; (ii) a relationship is seen between all base cations (Na⁺, K⁺, Ca²⁺, Mg²⁺), SO₄^2? and δ¹⁸O, indicating that solute acquisition is provided by solid–solution contact with the up‐sheared ice—as the relationship with Cl^? is weak the influence of seasalt‐derived solutes is small in the area; (iii) when the melt rate is high, two diurnal maxima of δ¹⁸O values and solute concentrations are measured, and it is suggested that a snow meltwater component is responsible for the second maximum of δ¹⁸O—a short residence time leads to a delayed decrease in ion concentrations. Copyright © 2003 John Wiley & Sons, Ltd.