1975-2015年鄂尔多斯市沙漠化的时空演变过程

鄂尔多斯市地处温带草原向荒漠草原过渡的半干旱区,是中国沙漠化问题较为严重的区域之一,其土地沙漠化发展和逆转过程及影响因素在北方农牧交错带具有代表性。以7期Landsat卫星遥感数据为信息源提取沙漠化土地类型及程度的时空格局信息,分析了该地区自1975年以来的土地沙漠化过程,并结合气象及社会经济数据采用主成分分析法对驱动因子进行定量分析。结果表明：在脆弱生态环境背景下,鄂尔多斯市土地沙漠化受人口数量增加、过垦及过牧等人为因素的严重影响。不同时段土地沙漠化发展的方向与驱动力都有所不同,1975-2000年是土地沙漠化的急剧发展期,驱动力以人为因素为主导,自然因素为基础;2000-2015年是土地沙漠化的逆转期,驱动力以自然因素为主,人为因素为辅。     

Integration of InVEST-habitat quality model with landscape pattern indexes to assess mountain plant biodiversity change: A case study of Bailongjiang watershed in Gansu Province

Journal of Geographical Sciences - Mountains in western China, hosted rich biodiversity and millions of people and inhabitant with vital ecosystem services, had experienced the most serious...     

MONITORING OF 1991 EASTERN CHINA FLOODING WITH POLAR ORBITING METEOROLOGICAL SATELLITES FY-1 AND NOAA

With polar orbiting meteorological satellites FY-1 and NOAA,flooding was monitored in the areas of the HuaiheRiver basin and the Taihu Lake region during June and July 1991.All satellite images from FY-1 and NOAA for concerned areas before and during flooding were examined.Thoseof cloud-free,with small amount of cumulus or thin cirrus were selected to exam the situation.Navigation and projec-tion were carefully performed,to ensure the projected images at different time overlap accurately with each other in 1—2pixels.Channel 1 (CH1) and Channel 2 (CH2) data of FY-1 and NOAA satellites with wavelength of 0.58—0.68μm and0.725—1.1μm were used to monitor the flooding.Albedo of Channel 2 and normalized vegetation index (NDVI) wereadopted as indicators to identify water body from land.With histogram and man-machine interactive methods,analysiswas done.In cloud-free condition,the two indicators identified the same area and scope of the water body.Totally cloud-free image in a large area is quite rare.To understand flood process,it is necessary to use more fre-quent images.It was investigated to distinguish water from land in partly cloudy condition.The result showed that whenthere is small amount of cumulus or thin cirrus,satellite images are still valuable in monitoring water body.In case ofmonitoring area covered with cirrus,vegetation index is useful,and while there is small amount of cumulus on land,albedo of Channel 2 can be used.Ten images from May 16 to August 18 of 1991 were examined.The results show that in the Lixiahe area,JiangsuProvince,the area submerged in total was the largest;along main stream of the Huaihe River,the Chuhe River,andaround the Chaohu Lake,a large percentage of area submerged;while in the Taihu Lake area,less field submerged.Flood monitoring was performed for 87 counties in the region concerned.These counties were put in order accord-ing to the percentage of submerged area in total.This order showed the extent of disaster at one view point.     

纬圈平均大气运动特征的振动

本文考虑高度非线性的大气中期运动是一种准涡旋运动,引用了准涡旋观点和方法来处理二维无辐散和三维运动方程,即在开始时保留涡旋项,而在对方程进行纬圈平均后,去掉一些涡旋项,得到了某些大气运动特征如西风指数、纬向动量和涡度的经向输送的纬圈平均值等的变化或摆动的振动方程,并求出谐波解。振动周期决定于经向动能二倍的纬圈平均值的平方根(v2)1/2。基本周期约二十天左右。所得结果可能对极端复杂的大气运动总有出现中期振动的趋势和精致设计的圆盘模拟实验出现摆动的事实,提供某种程度的动力学解释,同时也可能对中期预报的实践提供一些依据。本文的主要科学目的,是想指出对极端复杂的大气中期过程还是可能用线性理论来研究其某些特征的。     

北京地区气温诊断分析

本文讨论了北京地区百余年气温的变化特征，依据加法模型理论，提出了一种气候诊断和预测方法─—逐步回归多重因子方法，其优点在于将序列的周期因子、谱成分及外界气候振动因子同时引入回归模型中。这一方法，对单序列的气候诊断和预测具有明显效果。     

Investigation on semi-direct and indirect climate effects of fossil fuel black carbon aerosol over China

A Regional Climate Chemistry Modeling System that employed empirical parameterizations of aerosol-cloud microphysics was applied to investigate the spatial distribution, radiative forcing (RF), and climate effects of black carbon (BC) over China. Results showed high levels of BC in Southwest, Central, and East China, with maximum surface concentrations, column burden, and optical depth (AOD) up to 14 μg?m^?3, 8 mg?m^?2, and 0.11, respectively. Black carbon was found to result in a positive RF at the top of the atmosphere (TOA) due to its direct effect while a negative RF due to its indirect effect. The regional-averaged direct and indirect RF of BC in China was about +0.81 and ?0.95 W?m^?2, respectively, leading to a net RF of ?0.15 W?m^?2 at the TOA. The BC indirect RF was larger than its direct RF in South China. Due to BC absorption of solar radiation, cloudiness was decreased by 1.33 %, further resulting in an increase of solar radiation and subsequently a surface warming over most parts of China, which was opposite to BC’s indirect effect. Further, the net effect of BC might cause a decrease of precipitation of ?7.39 % over China. Investigations also suggested large uncertainties and non-linearity in BC’s indirect effect on regional climate. Results suggested that: (a) changes in cloud cover might be more affected by BC’s direct effect, while changes in surface air temperature and precipitation might be influenced by BC’s indirect effect; and (b) BC second indirect effect might have more influence on cloud cover and water content compared to first indirect effect. This study highlighted a substantial role of BC on regional climate changes.     

气象条件对高速公路路面抗滑性能影响的试验

对高速公路路面抗滑性能与温度、路面状况及使用融雪剂等不同条件的关系进行测试和分析,测试在实验室条件下和实际路面上分别进行。测试及分析结果表明:路面抗滑性能因气温和路面状况不同而有很大差异,尤其是冬季的冰雪和低温天气,对路面抗滑性能的不利影响最为显著。此外,气象条件与路面实际抗滑性能的关系还与其标准抗滑性能有关。     

长江三峡地区第四纪以来新构造上升速度和形式

本文以长江三峡地区各级夷平面和阶地作为重要标志,用地层学、古地磁测年、热释光测年和14C测年等手段,确定了它们的时代,从而分别计算2Ma、0.73Ma和0.2Ma以来的新构造上升速度。本文还探讨了新构造上升的特征:（1）长江三峡是一个以巴东为中心的不对称的新构造穹形隆起区,宜昌以东和万县以西是相对坳陷区;（2）2Ma以来,新构造上升节奏为缓慢—较快—较慢;（3）0.73Ma以来,新构造上升中心有向东迁移的趋势。     

基于数字化集中控制的气象视频会议系统

视频会议系统在气象行业应用较广,近年来随着多点(会议室)会议需求增加,设备复杂度提高,原有分立、单独管理模式对人员造成较大的压力。以湖北省气象局所建的数字化视频会议系统为例,在需求分析基础上,结合气象部门的信息网络条件,提出了基于数字化集中控制的视频会议系统建设方案。通过集中配备主要设备,对综合信号进行远程采集、分配,以数字化中控系统进行网络集中控制管理的方式,实现了召开多会议室、多会议模式的视频会议功能。业务应用情况表明,该方案既保证了视频会议效果和会场分布规模,又提高了管理效率,对同类系统的构建具有较好的参考价值。     

2015-2019年贵港市臭氧污染特征及其与气象要素的关系

为研究贵港市O3(臭氧)污染特征及其与气象要素的关系,对2015-2019年贵港市国家空气自动监测站和同期贵港国家气象观测站逐日、逐时气象资料进行了研究和分析.结果表明:近5a来贵港市O3污染日趋严重;O3污染存在明显的季节变化,秋＞夏＞春＞冬;O3浓度日变化特征呈单峰型,8:00出现谷值,15:00-16:00出现峰...