Temporal and Spatial Variations in the Climate Controls of Vegetation Dynamics on the Tibetan Plateau during 1982–2011

The ecosystem of the Tibetan Plateau is highly susceptible to climate change. Currently, there is little discussion on the temporal changes in the link between climatic factors and vegetation dynamics in this region under the changing climate.By employing Normalized Difference Vegetation Index data, the Climatic Research Unit temperature and precipitation data,and the in-situ meteorological observations, we report the temporal and spatial variations in the relationships between the vegetation dynamics and climatic factors on the Plateau over the past three decades. The results show that from the early 1980s to the mid-1990s, vegetation dynamics in the central and southeastern part of the Plateau appears to show a closer relationship with precipitation prior to the growing season than that of temperature. From the mid-1990s, the temperature rise seems to be the key climatic factor correlating vegetation growth in this region. The effects of increasing temperature on vegetation are spatially variable across the Plateau: it has negative impacts on vegetation activity in the southwestern and northeastern part of the Plateau, and positive impacts in the central and southeastern Plateau. In the context of global warming, the changing climate condition(increasing precipitation and significant rising temperature) might be the potential contributor to the shift in the climatic controls on vegetation dynamics in the central and southeastern Plateau.     

沙尘暴天气监测预警服务业务系统设计思路及其实现

文中全面介绍了中国西北地区沙尘暴天气监测预警服务业务系统的设计思路及其先进性。该系统由沙尘天气资料库、沙尘天气监测预警和沙尘天气服务3个子系统构成。它的成功建设为西部大开发气象服务提供了有力的技术保障，为西部地区环境保护和环境监测奠定了基础。     

基于资源卫星图像对NDVI进行大气修正的一种简单方法

在遥感应用领域，植被指数己被广泛用来定性和定量表征植被覆盖度及其生长状况。由于大气变化的影响，使植被指数未能真实反映地表植被的真实分布状况，造成其应用的局限性。提出了一种简易方法，仅通过中巴资源卫星(CBERS：China Brazil Environment Resoure Satellite)图像的第3、第4波段中的水体，推算卫星接收到的大气程辐射，消除了大气对归一化植被指数(NDVI：Normalized Differece Vege—tation Index)的影响，减小植被指数所受的大气影响。应用结果表明，该方法能使植被指数较好地反映植被的生长及分布状况。     

基于综合监控和负载调控的中国天气网网站弹性架构

中国天气网是中国气象局面向公众提供气象信息服务的核心门户。为适应其日益增长的访问量,并保障网站可用性及访问体验等要求,网站已建立包含可用性、用户体验、网站访问、网络、安全、系统和应用等多方面的综合监控系统。实现了可根据体验、可用性、成本、安全等多方面因素,可面向多种具体业务场景的灵活多样的负载调控手段。基于监控和调控,构建了经内容本地加速的多源站弹性架构。在访问体验、可用性、带宽容量、安全、成本、业务特性需求等多方面提升了网站能力。     

玉米冠层反射率及净辐射的估算

在1994~1996年3年田间试验的基础上,根据玉米生长状况及其冠层特征,选取包括植株高度、平均叶面积密度、农田覆被率等植物特征量组成的植物参数——综合植被系数来描述玉米冠层状况,并以此为因子来估算玉米冠层的反射率和净辐射,取得了良好的结果。     

2000—2021年江西省植被生态质量时空分布及其与气候因子的关系

基于卫星遥感数据和气象数据,采用距平分析、趋势分析、相关性分析等方法,分析了2000—2021年江西省植被生态质量时空变化特征,及其与气温、降水、日照等气候因子的关系。结果表明：1） 自2000年以来江西省植被生态质量整体改善明显,植被净初级生产力和生态质量指数呈明显上升趋势,年平均分别增加3.92 gC/m2和0.4,尤其2011年以后植被净初级生产力和生态质量指数处于较高水平,其中2018年最佳。2） 江西省植被生态指标低值区域位于城区周边,以及由长江和江西五大河流域的泥沙沉积形成的、以鄱阳湖为中心的冲积平原,中值区域位于中南部丘陵,高值区域分布于省境边陲山脉。3） 江西省植被生态指标与年降水量、年平均气温呈显著相关关系,与日照时数相关性不显著。与气候因子的相关性呈现地域差异,南部区域受气温影响较为明显,而中部盆地和东北区域受降水量影响更为明显。     

2004年广东省干旱灾害遥感监测应用研究

针对广东省气候湿润、植被覆盖度高的特点,以NOAA/AVHRR资料为数据源,采用植被供水指数法,对2004年广东省发生的50年来最严重的一次干旱灾害进行遥感动态监测,并结合土地利用分类数据,采用掩膜技术提取干旱分类信息.研究结果表明,10月上旬全省部分地区出现旱情,10月下旬全省受旱总面积达到峰值,占全省面积的72.6%;11月上旬后期受旱面积有所减少,中旱、重旱区域有所增加,其后旱情总体呈减缓趋势,但在12月中旬出现了短暂的增加趋势.以11月上旬为例的干旱灾害分类研究还表明,水田、旱地、灌木、林地等不同的用地类型,其受旱比例依次递减.该研究结果较好地反映了本次干旱灾害的空间分布及发展过程,为相关部门进行干旱灾情评估、制定和实施抗旱减灾措施提供了科学依据.     

古新世-始新世暖期北半球野火演化研究

古近纪是现代气候和植被形成的关键过渡期, 而野火活动与气候、植被和碳循环等存在耦合关系。开展古新世-始新世(66~34 Ma)3个特征暖期, 即古新世-始新世极热事件(PETM, 约55.9 Ma)、早始新世气候适宜期(EECO, 53.3~49.1 Ma)、中始新世气候适宜期(MECO, 约40.5~40.1 Ma)的野火活动研究, 对于揭示气候和植被变化特征及其影响具有重要意义。本研究基于蒙古高原南部二连盆地古新世-始新世野火记录, 并结合北半球该时段其他12个地点的野火研究数据, 从长尺度地质记录视角, 重建北半球野火活动特征与演变, 并探讨其驱动机制。研究结果显示古新世-始新世不同特征暖期野火发生规模和强度存在差异, PETM极端暖期较EECO和MECO暖期野火强度更大, 但不十分显著。古新世-始新世暖期并没有持续的、大规模的野火发生, 呈现"低野火状态", 总体不支持强调燃烧活动影响全球碳循环的"野火假说"。通过野火发生与温度、降水、植被以及CO2浓度等环境因子之间的关系分析, 对"古近纪低火谜题"进行初探, 认为古新世-始新世气候的季节性并不分明, 较短的干季不利于可燃"燃料"和潜在火源的形成, 很可能是新生代早期"低野火"的主因。     

CHARACTERISTICS OF VEGETATION COVER,ROUGHNESS AND ALBEDO DISTRIBUTION OVER CHINA

To build land surface dataset for climate model,with application of remote sensing techniqueas well as the Geographic Information System(GIS),the data of surface type,roughness andalbedo over China in 1997 were retrieved,resolutions being 10 km×10 km.Based on these data,an analysis is conducted on the geographic distributions and seasonal variations of surfacevegetation cover and roughness as well as albedo over China.Results show that surface vegetationcover is mainly located to the south of Yangtze River,in Southwest and Northeast China andsparse vegetation cover is in the Northwest.The variation of land surface cover affects thevariations of land surface roughness and albedo.High albedo occurred in the north of XinjiangAutonomous Region,the north of Northeast China and the Qinghai-Xizang Plateau in winter,incorrespondence with the location of snow cover.For most part of China,surface roughness decreases and albedo increases in winter,while theroughness increases and the albedo decreases in summer,which could mainly result from landsurface cover(snow cover and vegetation cover)and soil moisture changes.This shows that thegeographic distribution and seasonal variation of the albedo are almost opposite to those of theroughness,in agreement with theoretical results.Temporally,the amplitude of surface roughnesschange is quite small in comparison with the roughness itself.     

Dynamik der Schilfröhrichte am Bodensee unter dem Einfluss von Wasserstandsvariationen

On the basis of different sets of aerial photos the dynamics of the reed bed areas of Lake Constance were investigated in relation to the dynamics of the water levels. The objectives of the study were to quantify the changes of reed areas due to different flood events in the last decades and their recovery in the time periods between these events. The results should given information of the relevance of water level variations on reed bed dynamics and the regeneration times of reed beds after extreme disturbance events.Following the extreme flood at Lake Constance in 1999 the reed belts of Lake Constance lost approximately 30 ha (24%) of the lakeside reed beds. The loss is comparable to the situation in the late 1960s, when approximately 40 ha died back due to the extreme flood in 1965 and the high spring water levels in the subsequent years. In the time period between the extreme floods of 1965 and 1999, the reed areas expanded to nearly 85% of the area before 1965. The expansion rates increased with increasing distance to the flood event of 1965. Especially in periods with series of years of low spring water level the expansion rates were high.The damage degrees of the reed areas in the years 2000 and 2002 showed a clear relation to the elevation (i.e. average water level) of the stands. The damage degree increased with decreasing elevation. Furthermore the regeneration process of severely damaged stands was related to the elevation level of the stands. Whereas stands at high elevation regenerate fast, those at low elevation died off completely in the years after the extreme flood. This supports the hypothesis that the water level flutuations play a major role in the reed dynamics of Lake Constance.As a consequence of the climate change an increase in the frequency of high spring water levels is expected. Thus, it seems unlikely that reed stands will ever expand again to the same area as before 1965.