二氧化碳浓度增加对冬小麦生长发育影响的数值模拟

根据国内外小麦生长模拟研究成果,借鉴荷兰学者的模拟思路,从作物生长的主要生理过程人手,综合考虑气候变暖与大气中CO2浓度增加等因素对作物生长发育和产量形成的影响,修正了在一级生产水平下冬小麦生长模拟模式,使得模式能够对CO2浓度的变化做出相应的反应。经资料检验,在当前CO2浓度下,冬小麦总干重和穗干重的模拟平均相对误差小于10％,其它器官干重及叶面积指数的模拟也取得了较好的结果。运用改进后的模式模拟试验了未来气候变暖和CO2倍增对冬小麦生长发育的可能影响。     

CO2快速测定方法的应用研究

在新疆水磨沟形变站院内 ,布设了一个 CO2 快速测定法观测点。 2 0 0 1年 7月 4日呼图壁 MS3.9级地震前 ,在该观测点观测到了明显的短临异常     

Quantifying CO2 fluxes from soil surfaces to the atmosphere

Measurements of CO₂ fluxes from ground surface of the atmosphere (soil respiration) are needed to quantify biotic and abiotic reaction rates in unsaturated zones and to gain insight into the importance of these processes on global warming. The use of three techniques (dynamic closed chambers, static chambers, and gradient calculations) to determine soil respiration was assessed by measuring fluxes of microbially produced CO₂ from an unsaturated mesocosm (2.4 m dia.×3.2 m thick) and two unsaturated minicosms (0.58 m dia.×1.2 m thick), one maintained at 18–23 °C (HT) and the other at 5 °C (LT). By injecting known and constant CO₂ fluxes into the bottom of the HT minicosm and measuring the resulting fluxes, it was shown that the dynamic closed chamber (DCCS) technique yielded accurate measurements of fluxes over the range observed from natural unsaturated media. Over this same range, results showed that the concentration gradient method yielded reasonable estimates of fluxes but its accuracy was limited by uncertainties in both the concentration gradient and the gaseous diffusion coefficient in the soil atmosphere. The static chamber method underestimated the actual flux at higher CO₂ fluxes and when adsorption times of >24 h were used.     

世界气候变暖及二氧化碳埋存现状与展望*

由于CO₂大量排放而引起的全球气候变暖问题日趋严峻。21世纪环境保护受到国际社会高度关注,全球气温上升控制目标比工业革命前水平高2 ℃以内,因此必须采取积极有效措施。捕获和埋存废气中的CO₂是避免气候变化的有效途径之一,同时要求CO₂须埋存几百或几千年。埋存对环境产生的影响最小、成本较低且遵守国际法规。CO₂地下埋存的主要场所是枯竭的油气藏、深部的盐水储集层、不能开采的煤层和深海等。CO₂地下埋存可应对因能源需求增长和CO₂排放量增加带来的挑战,必将为全球资源及环境的高水平、高效益开发和可持续发展提供理论及实践依据。     

GALILEO试验星GIOVE—A信号质量分析

介绍了GIOVE-A卫星信号,分析了GIOVE-A卫星信号质量;与GPS CA码信号质量进行了比较。     

居住自选择视角下的广州出行碳排放影响机理

国内外已有不少研究从国家、城市和社区层面探讨了交通出行碳排放的影响因素,然而,很少研究考虑到居住自选择的影响。若忽略该影响,将很可能会错误地估计建成环境的作用,以至于相关规划与政策制定有所偏离。中国城市是否与西方国家一样也具有居住自选择效应?在考虑了居住自选择后,建成环境是否对出行碳排放具有显著的影响,如何产生影响?为了回答以上科学问题,基于2015年广州15个社区1239份问卷数据和出行O-D点智能查询系统（TIQS）的开发与应用,对居民出行碳排放进行了测度,并通过构建结构方程模型（SEM）探究了不同类型出行碳排放的影响机理。研究发现：中国城市同样存在居住自选择效应,转变居民出行方式选择偏好有利于减少出行碳排放。在控制居住自选择效应后,建成环境仍然对居民出行碳排放产生显著的影响。这些影响有的属于直接影响,有的则是通过影响其他中介变量,例如小汽车拥有或出行距离,进而再对出行碳排放造成间接影响。对于不同类型出行,其碳排放的影响机理并不一样。     

The molecular composition of Comet C/2007 W1 (Boattini): Evidence of a peculiar outgassing and a rich chemistry

We measured the chemical composition of Comet C/2007 W1 (Boattini) using the long-slit echelle grating spectrograph at Keck-2 (NIRSPEC) on 2008 July 9 and 10. We sampled 11 volatile species (H₂O, OH^∗, C₂H₆, CH₃OH, H₂CO, CH₄, HCN, C₂H₂, NH₃, NH₂, and CO), and retrieved three important cosmogonic indicators: the ortho-para ratios of H₂O and CH₄, and an upper-limit for the D/H ratio in water. The abundance ratios of almost all trace volatiles (relative to water) are among the highest ever observed in a comet. The comet also revealed a complex outgassing pattern, with some volatiles (the polar species H₂O and CH₃OH) presenting very asymmetric spatial profiles (extended in the anti-sunward hemisphere), while others (e.g., C₂H₆ and HCN) showed particularly symmetric profiles. We present emission profiles measured along the Sun-comet line for all observed volatiles, and discuss different production scenarios needed to explain them. We interpret the emission profiles in terms of release from two distinct moieties of ice, the first being clumps of mixed ice and dust released from the nucleus into the sunward hemisphere. The second moiety considered is very small grains of nearly pure polar ice (water and methanol, without dark material or apolar volatiles). Such grains would sublimate only very slowly, and could be swept into the anti-sunward hemisphere by radiation pressure and solar-actuated non-gravitational jet forces, thus providing an extended source in the anti-sunward hemisphere.     

不同实验条件下GPS伪距定位精度分析

研究概括了在不同的实验条件下利用GPS伪距获得较高精度定位结果的方法。实验结果的精度表明,这些方法的定位结果都能比常规的GPS伪距定位法的结果精度高,而且定位效果稳定。同时该方法也可为后续高精度定位及定轨等研究工作打好基础。     

Some results of solar radio emission observations at the Siberian Solar Radio Telescope

This paper gives the main characteristics of the Siberian Solar Radio Telescope as well as some results derived by investigating the s-component sources and radio bursts on the Sun using the SSRT.     

淮河流域南部丘陵森林地区土壤-植被-大气相互作用:长期野外试验观测的初步分析

本文简要介绍了包括三部分观测的安徽淮南长期野外试验观测站,特别是土壤-植被-大气的集中观测,对小塔运行前三个月(2018年6月至8月)的数据,并结合同一时段大塔获得的数据,进行了初步分析.结果表明这些资料有合理的变化特征,日变化和夏季值特征显著,各月份间气象变化有明显差异.土壤水分和温度受降雨影响,在不同的下垫面条件下...