中国省域农业碳生产率的空间分异特征及依赖效应

科学测度农业碳生产率并探究其空间关联状况是构建兼具差异化和协调性的碳减排政策的基石。本文对2001-2012年中国31个省（市、区）的农业碳生产率进行测度,在此基础上利用空间相关性指数对其空间相关性、聚类状况进行考察,并运用空间杜宾模型分析农业碳生产率变动的主要影响因素及空间效应。结果表明：①2001-2012年中国各省区农业碳生产率均呈现较为明显的提升趋势,除个别省域外,省域农业碳生产率与其所属地区的经济发展程度基本一致;与此同时,农业碳生产率区域间“异质化”与区域内“均质化”的趋势显现,且以地区间农业碳生产率的“分化”与“极化”的现象较为严重;②省域农业碳生产率存在着较强的空间自相关性,各省区农业产业结构对本地区农业碳生产率具有负向影响,农村教育水平和农业开放程度对其具有正向影响,而农业经济发展水平、受灾程度和农业公共投资对其影响不甚明显;此外,省域农业碳生产率在空间上存在较为明显的溢出效应,其中一省区农村教育水平和农业开放水平对邻域农业碳生产率的提高具有正向带动作用,农业经济发展水平对其则起到抑制作用,而农业产业结构、自然灾害和农业公共投资对周边地区农业碳生产率的影响并不明显。     

1900年以来贝加尔湖水位变化及其原因分析

水位变化作为湖泊水文过程和水量平衡的动态反映,是湖泊生态环境的重要影响因素。全球最大的淡水湖——贝加尔湖,在自然变化与人为活动的双重影响下,过去100多年水位表现出较大的年内、年际和多年变化。贝加尔湖水位变化与入湖径流量变化密切相关,与贝加尔湖最大支流色楞格河的径流量变化较为一致。气候变暖带来的气温上升和降水减少使得入湖径流量减少,贝加尔湖水位下降。人类活动对贝加尔湖水位变化影响表现在两个方面：一方面,全球变暖条件下耕地面积扩张和灌溉用水增加导致贝加尔湖流域用水增加,使得入湖径流量减少,贝加尔湖水位下降;另一方面,1958年伊尔库茨克水电站投入运营之后,贝加尔湖水位变化受到了安加拉河水位顶托的影响。在下游水电站人为调控影响下,贝加尔湖年平均水位升高,年内水位波动幅度增加,年最低和最高水位出现日期推迟。地处全球气候与环境变化敏感区的贝加尔湖,其水位变化对湖泊及周边生态环境影响显著。因此,探究在全球变化背景下贝加尔湖的水位变化及影响因素对保护当地生态环境具有重要意义。     

深圳冬季多层地温日变化特征

分析深圳冬季不同天气影响下地温日变化,结果表明,没有冷空气影响的晴天,地面温度和浅层地温呈现正弦曲线日变化,白天高,夜间低. 各层地温振幅、位相不同,地面温度振幅最大,越往深层,振幅越小,位相越后,周期越长. 地温垂直结构也有日变化,正午时段从地面到40cm 土壤,温度随深度降低,40cm 以下地温随深度升高. 凌晨从地面至320cm 土壤,地温依次升高. 冷空气影响下的阴天,地面温度和浅层地温也呈现正弦曲线日变化,但日变化幅度远小于晴天;地温垂直结构,除了正午前后几个小时地面温度要高于5cm 地温外,其他时间从地面到320cm 土壤,温度依次升高. 冷空气影响下的阴雨天,地面温度和浅层地温随时间逐步降低,地温从地面到320cm 土壤依次升高. 无论是晴天、阴天,还是阴雨天,160cm 以下深层地温,其日变化幅度均小于0.2℃.     

The variation of the residual ionization with pressure at different altitudes,and its relation to the cosmic radiation

Measurements have been made of the residual ionization in a closed vessel of steel one inch thick, shielded by a two inch casing of lead, over a range of pressure from atmospheric to one thousand pounds per sq. inch, at Pike's Peak (alt. 14,000 ft.), Colorado Springs (alt. 6,ooo ft.), and New Haven (alt. 6,000 ft.). The ionization-pressure curves presents features of interest in relation to the interpretation of the processes associated with ionization in the vessel. However, in the present investigation they are used simply to obtain average relative value of the ionization due to the cosmic rays at the three altitudes concerned. A method of correcting the observations for absorption by the iron sphere, the lead case, and the walls of the buildings, has been developed. It is found that the data for the three stations can be correlated by the assumption of a pair of frequencies in the original cosmic radiation; and, as a matter of fact, an infinite number of such pairs are possible. They are represented in graphical form in Fig. 7 If we permit the assumption of three different frequencies in the cosmic radiation, it is possible in general to assign two of the frequencies, and determine an infinite number of possibilities as regards the third, distributed over a definite range. The possibilities inherent in the assumption of three frequencies are contained in tabular form in Table XVII. Of course, the inclusion of observations from more than three altitudes would serve to fix more definitely the possibility as regards the analysis. However, the result of the analysis for the three stations concerned is possibly of interest for comparison with other data, and as an indication of the kind of information which it is possible to extract from observations of this kind. It is probable that the very large range of possibilities inherent in a solution with three coefficients of absorption will be rather surprising to anyone who considers a situation of this kind for the first time.In addition to those whose assistance has already been acknowledged, I wish to acknowledge the assistance of Professor J. W. Broxon, who visited me while on Pike's Peak, and assisted in setting up the apparatus; and my thanks are due to Mr. C. A. Kotterman, and particularly to Mr. Andrew Longacre, and Mr. W. E. Ramsey for assistance in the reduction of the observations, and in the computational work.     

精密测量雷达大气折射误差的实时修正方法探讨

文章主要介绍了大气折射对雷达测量数据的影响,通过大气模型来计算折射率,分析对雷达数据造成的影响,并得出修正公式.     

贵州省极端气温时空变化特征分析

随着全球变暖趋势加剧,西南地区极端天气事件频发,对国民经济发展和生态环境保护构成了严重威胁。利用1960—2016年33个气象站点的逐日气温数据集,采用线性趋势、滑动平均、空间插值、M-K突变检验等方法,对贵州极端气温时空变化特征及影响因素进行分析。结果表明：贵州极端气温暖系列指数呈上升趋势,夏日日数、暖日日数、热持续指数、热持续发生次数的年际变化倾向率分别为：0.6d/10a、2.7d/10a、0.02d/10a、0.2次/10a;冷系列指数呈下降趋势,霜冻日数、冷夜日数、冷持续指数、冷持续发生次数的年际变化倾向率分别为-1.6d/10a、-8.0d/10a、-0.5d/10a、-1.0次/10a,进入21世纪后升温速度加快。极端气温表现出非对称性现象,冷系列极端气温指数变化幅度大于暖系列指数,其中暖日日数升幅最大,冷夜日数降幅最大,且与海拔关系密切。多数极端气温指数突变发生在19世纪末到21世纪初。厄尔尼诺对暖系列指数影响较大;拉尼娜对冷系列指数影响较大,在次年其影响程度达到最高水平。     

The variation of secondary emission with heat treatment

The ratio of the number of electrons striking a surface to the number leaving it was determined under various conditions for a number of metals contaminated by the condensation of grease vapors on them.The curves showing the variation of secondary emission with incident electron energy (evidently characteristic of the contamination rather than of the metals) are similar for all the targets and resemble the results obtained by Gehrts. Reducing the amount of the contamination by heating the metals at first reduces the secondary emission until it falls below that expected from a clean metal. The emission then increases with further heating and the characteristics of the metal appear. The variation of the work function during the “outgassing” process is indicated by this increase of the secondary emission followed by a decrease of the secondary emission as the process continues.     

Thermodynamics; work,heat, and temperature concepts,and an examination of the temperature scale

In this paper the concepts of work, heat, and temperature are examined from the stand-point of a complete equation (1) 2 for the internal energy of a system. In an incomplete system energy necessarily remains with the system, which results in the inefficiency of a process. This inefficiency is, of course, appreciable for processes taking place at a finite speed, but is not necessarily eliminated by means of a quasistatic process.The Kelvin temperature scale is shown to be based on an incomplete equation for the internal energy and, therefore, offers certain difficulties. A temperature scale based on a complete equation is shown to have advantages over the Kelvin scale, and it is further shown that the temperature of absolute zero as based on a complete equation is lower than that on the Kelvin scale.A suggestion is offered whereby an actual system may be treated as complete and a temperature scale may be based on this.