东亚土地覆盖动态与季风气候年际变化的关系

以东亚地区1982－1989年时间序列降水资料及AVHRR 8km NDVI数据为基本数据源，应用地理信息系统技术，分别研究了东亚地区夏季（5－9月）降水及土地覆盖的年际变化，并揭示了研究时间段内各自的变化规律。进一步用奇异值分解（SVD）模型方法分析了以降水变化为表征的东亚地区气候年际变化与土地覆盖年际变化之间的关系。     

东亚夏季风的年际变化及其对环流和降水的影响

Using NCEP/NCAR reanalysis geopotential height (GHT) and wind at 850 hPa, GHT at 500 hPa, precipitation rate, sea level pressure (SLP) and precipitation observations from more than 600 stations nationwide in June–August from 1951 to 2006, and focusing on the East Asia-West Pacific region (10°–80°N, 70°–180°E), interannual variation of East Asian summer monsoon (EASM) and its correlations with general circulation and precipitation patterns are studied by using statistical diagnostic methods such as 9-point high pass filtering, empirical orthogonal function (EOF) analysis, composite analysis and other statistical diagnosis, etc. It is concluded as follows: (1) EOF analysis of SLP in the East Asia-West Pacific region shows the existence of the zonal dipole oscillation mode (APD) between the Mongolia depression and the West Pacific high, and APD index can be used as an intensity index of EASM. (2) EOF analysis of GHT anomalies at 500 hPa in the East Asia-West Pacific region shows that the first EOF mode is characterized with an obvious meridional East Asian pattern (EAP), and EAP index can also be used as an EASM intensity index. (3) The composite analysis of high/low APD index years reveals the close correlation of APD index with EAP at 500 hPa (or 850 hPa). The study shows an obvious opposite correlation exists between APD index and EAP index with a correlation coefficient of −0.23, which passes the confidence test at 0.10 level. (4) Both APD and EAP indexes are closely correlated with precipitation during flood-prone season in China and precipitation rate over the East Asia-West Pacific region. The significant correlation area at 5% confidence level is mainly located from the southern area of the Yangtze River valley to the ocean around southern Japan, and the former is a positive correlation and the latter is a negative one. Foundation: Cooperative Project funded by the Ministry of Science and Technology of the People’s Republic of China, No.2007DFB20210; National Natural Science Foundation of China, No.90502003; JICA China-Japan Technical Cooperative Project “China-Japanese Cooperative Research Center on Meteorological Disasters”. Author: Yu Shuqiu, Associate Professor, specialized in climate and climate change.     

近159 年东亚夏季风年代际变化与中国东部旱涝分布

利用1850-2008 年我国东部地区90 个测站的旱涝等级和北半球夏季海平面气压格点等资料,使用BP 典型相关等方法,分析了近159 年旱涝等级与东亚夏季海平面气压的耦合相关关系。利用关键区域的海平面气压资料,定义出与我国东部旱涝分布有密切联系的东亚夏季风指数,在此基础上分析了东亚夏季风年代际变化对我国东部旱涝分布的影响。结果表明：(1) 近159 年中国东部旱涝具有4 种典型空间分布型,即华南与中国东部其他地区旱涝趋势相反型、黄淮地区与长江流域及其以南旱涝趋势相反型、江淮流域与中国东部其他地区旱涝趋势相反型和中国东部与西部旱涝趋势相反型。近159 年东亚夏季海平面气压场主要呈现亚洲大陆与西太平洋海平面气压强弱相反的分布特征;(2) 本文定义的夏季风指数的年代际变化与我国东部旱涝典型分布型的年代际变化有密切关系,但两者的相关关系并不是稳定不变的,存在显著的年代际位相差异,即20 世纪20 年代之前,当东亚夏季风偏强(弱) 时,长江流域以北容易偏旱(偏涝),长江流域及其以南容易偏涝(偏旱),20 世纪20 年代以后,当东亚夏季风偏强(弱) 时,长江流域以北容易偏涝(偏旱),长江流域及其以南容易偏旱(偏涝)。可见,使用较长年代资料进行考察,研究结论丰富了大多数使用近50-60 年资料的研究结果。东亚夏季风与我国东部旱涝分布之间关系的年代际位相差异,可能与东亚夏季风对太阳活动等外强迫的非线性反馈相联系     

土地利用/土地覆盖变化与土壤侵蚀关系研究进展

土壤侵蚀作为LUCC引起的主要环境效应之一,是自然和人为因素叠加的结果。不合理的土地利用和地表植被覆盖的减少对土壤侵蚀具有放大效应。土地利用/土地覆盖变化与土壤侵蚀关系的研究已逐渐成为LUCC研究和土壤侵蚀研究的一项新的重要课题。目前,涉及土地利用/土地覆盖的土壤侵蚀研究方法有很多,本文介绍了基于模型的定量研究、基于GIS和RS的研究、基于放射性同位素的研究以及基于湖泊(水库)沉积物的研究的基本原理与研究进展,同时指出了每种方法中存在的不足。     

东亚土地覆盖环境背景数字地面模型研究

应用地理信息系统、遥感技术及数字地面模型方法,选取影响东亚土地覆盖环境背景的主要因素高程带、坡度、坡向、气温、降水量、最大可能蒸散量、湿润度及植被指数等指标,在统一的投影、统一的空间分辨率、统一的空间范围等前提下,对它们进行单要素的专题数字地面模型研究,并用主成份分析方法将各单项数字地面模型进行集成,生成包含各单项要素特征的综合性的数字地面模型,最后对综合性数字地面模型所反映的东亚土地覆盖环境背景特征作了分析     

1974-2011年白洋淀土地覆盖时空变化特征

在野外调查的基础上,运用遥感和地理信息系统技术对1974年、1979年、1984年、1987年、1989年、1991年、1996年、2001年、2006年和2011年10期遥感影像进行解译和分析,揭示了白洋淀近37年土地覆盖动态变化。结果表明:近37年白洋淀土地覆盖类型变化极为复杂,主要表现为水体、芦苇地、耕地3种土地覆盖类型相互转化。1974-2011年,水体面积从58.01 km2上升到80.07 km2,芦苇地面积从104.94 km2下降到72.95 km2,水生植被从14.02 km2下降到4.27 km2。1974-2011年,耕地、水体、芦苇地、居民点转化为其它类型的比例相对较小,分别为39.25%、34.46%、53.74%和18.15%。水体面积增加主要分布在地势较低的东部和北部地区,水体面积减少主要分布在地势较高的西南地区。水位变化、入淀径流量变化、淀区气候变化、人类活动及管理政策是白洋淀土地覆盖变化的驱动因子。研究揭示了白洋淀土地覆盖与人类活动的相互作用关系,对白洋淀土地管理和生态系统服务可持续供给具有重要意义。     

Relationship between land cover and monsoon interannual variations in east Asia

Asian monsoon have multiple forms of variations such as seasonal variation, intra-seasonal variation, interannual variation, etc. The interannual variations have not only yearly variations but also variations among several years. In general, the yearly variations are described with winter temperature and summer precipitation, and the variations among several years are reflected by circulation of ENSO events. In this study, at first, we analyze the relationship between land cover and interannual monsoon variations represented by precipitation changes using Singular Value Decomposition method based on the time series precipitation data and 8km NOAA AVHRR NDVI data covering 1982 to 1993 in east Asia. Furthermore, after confirmation and reclassification of ENSO events which are recognized as the strong signal of several year monsoon variation, using the same time series NDVI data during 1982 to 1993 in east Asia, we make a Principle Component Analysis and analyzed the correlation of the 7th component eigenvectors and Southern Oscillation Index (SOI) that indicates the characteristic of ENSO events, and summed up the temporal-spatial distribution features of east Asian land cover’s inter-annual variations that are being driven by changes of ENSO events.     

基于多期数据集的中亚五国土地利用/覆盖变化分析

针对目前中亚地区土地利用变化和分布格局方面的信息相对匮乏,现有资料较为陈旧且零散,无法满足中亚生态与环境变化研究需求的现状,利用全球的UMD, DISCover,GLC2000,GlobCover2005和GlobCover2009的5期土地覆被遥感数据集,提取中亚地区长时间序列土地覆被信息。并针对上述4个土地覆被分类系统无法进行直接对比和变化分析的问题,分别将其综合为4类土地覆被类型：耕地、自然植被、水体和其他,以分析近30 a中亚土地利用/土地覆被变化趋势。中亚土地利用类型多样,草地、裸地、农田、灌丛占绝对优势。自前苏联解体以后,20世纪90年代初至2000年期间,耕地面积大幅度减少,至2010年尽管有所恢复,但仍无法达到20世纪90年代初水平。而自然植被表现出了相反的趋势,这说明在此时间段内,由于社会政治制度的变化和市场经济的建立,耕地发生了较大规模的弃耕,弃耕地通常转换为草地、灌丛等自然植被。近10 a由于社会经济条件的变化,前苏联解体后所弃耕的土地又被收复和重新开发为耕地。90年代初至2000年期间,水体呈现先减少后增加的趋势。利用全球基于多期不同信息源获得的中亚土地覆被数据,尽管分类体系不统一,但均可较好地表征当时地表覆被状况。这在一定程度上弥补了中亚地区土地覆被数据不足的现状。通过对耕地、自然植被、水体及其他土地覆被类型进行大类合并,可基本体现中亚土地覆被的宏观特征和变化趋势。     

Spatial distributions and interannual variations of snow cover over China in the last 40 years

By using the observational snow data of more than 700 weather stations,the interannual temporal and spatial characteristics of seasonal snow cover in China were analyzed.The results show that northern Xinjiang,northeastern China-Inner Mongolia,and the southwestern and southern portions of Tibetan Plateau are three regions in China with high seasonal snow cover and also an interannual anomaly of snow cover.According to the trend of both the snow depth and snow cover days,there are three changing patterns for the seasonal snow cover:The first type is that both snow depth and snow cover days simultaneously increase or decrease;this includes northern Xinjiang,middle and eastern Inner Mongolia,and so on.The second is that snow depth increases but snow cover days decrease;this type mainly locates in the eastern parts of the northeastern plain of China and the upper reaches of the Yangtze River.The last type is that snow depth decreases but snow cover days increase at the same time such as that in middle parts of Tibetan Plateau.Snow cover in China appears to have been having a slow increasing trend during the last 40 years.On the decadal scale,snow depth and snow cover days slightly increased in the 1960s and then decreased in the 1970s;they again turn to increasing in the 1980s and persist into 1990s.     

中国降水量变化的空间分布特征与东亚夏季风

利用NCEP/NCAR海平面气压场和中国站点月降水量资料,研究了中国近47 a来的降水量变化空间分布特征及东亚夏季风与中国夏、秋季降水的关系.1961-2007年中国年降水量减少的区域主要在东北、华北、西北东部、西南东部和华南西部,形成一个东北一西南向的带状区域,其余大部为增加趋势,其中陕西北部和四川中南部减少趋势显著...     

中国北方春季沙尘暴频数与北半球500hPa高度场的SVD分析

选取1957-2000年中国北方地区春季沙尘暴发生次数资料和北半球500hPa秋、冬、春季的平均高度场资料,对沙尘暴和高度场作SVD分析。结果表明,我国北方春季沙尘暴次数各地具有比较一致的变化趋势,表明可能与大尺度气候背景的变化有联系。变化的最敏感区域为内蒙古中西部地区、新疆西部、青海西部和东北地区。我国北方春季沙尘暴发生次数与同期及前期500hPa高度场有较好的相关关系,前期环流形势对春季沙尘暴频数有一定的指示和预测意义,冬季环流场尤其具有预报指示意义,因为前一年冬季北大西洋涛动对我国春季北方沙尘暴发生次数有影响。     

气候和地貌对晚第四纪冰川发育差异性的影响

中国第四纪冰川作用极大地推动了高亚洲乃至全球冰川形成机制的探讨。青藏高原以及喜马拉雅山地冰川作用的时限和规模研究得到了广泛关注,为西风带与西南季风带对晚第四纪冰川作用差异性问题的解决提供了有利条件。然而,对于中亚西风环流与东亚季风环流影响下的冰川演化差异性关系不甚明确,两大气候系统控制下的山地第四纪冰川的冰进时序、冰期历史和冰川规模显示出不同特点,其差异性主要体现在:西部山地的冰期启动时间早,冰川规模随时间而逐渐缩小,冰川历史较为完整,绝对年代证据显示冰川作用的启动时间是450 ka 左右的中梁赣冰期(MIS12);东部山地的冰期历史较短,仅保留末次冰期(~75 ka)的冰川遗迹,冰川作用的阶段性明显;冰川演化时间与空间的差异性表明,影响冰川发育的因素不仅仅是区域气候,构造因素也起着相当重要的作用。     

Vertical distribution changes in land cover between 1990 and 2015 within the Koshi River Basin,Central Himalayas

The study of mountain vertical natural belts is an important component in the study of regional differentiation.These areas are especially sensitive to climate change and have indicative function,which is the core of three-dimensional zonality research.Thus,based on high precision land cover and digital elevation model (DEM) data,and supported by MATLAB and ArcGIS analyses,this paper aimed to study the present situation and changes of the land cover vertical belts between 1990 and 2015 on the northern and southern slopes of the Koshi River Basin (KRB).Results showed that the vertical belts on both slopes were markedly dif-ferent from one another.The vertical belts on the southern slope were mainly dominated by cropland,forest,bare land,and glacier and snow cover.In contrast,grassland,bare land,sparse vegetation,glacier and snow cover dominated the northern slope.Study found that the main vertical belts across the KRB within this region have not changed substantially over the past 25 years.In contrast,on the southern slope,the upper limits of cropland and bare land have moved to higher elevation,while the lower limits of forest and glacier and snow cover have moved to higher elevation.The upper limit of alpine grassland on the northern slope retreated and moved to higher elevation,while the lower limits of glacier and snow cover and vegetation moved northward to higher elevations.Changes in the vertical belt were influenced by climate change and human activities over time.Cropland was mainly controlled by human activities and climate warming,and the reduced precipitation also led to the abandonment of cropland,at least to a certain extent.Changes in grassland and forest ecosystems were predominantly influenced by both human activities and climate change.At the same time,glacier and snow cover far away from human activities was also mainly influenced by climate warming.     

Unplanned urban growth: land use/land cover change in the Guwahati Metropolitan Area,India

Unplanned urban growth, particularly in developing countries has led to changes in land use/land cover (LULC). Numerous Indian cities face problems of unplanned LULC change due to nominal or non-existent planning efforts compounded by rapid urban population growth. The Guwahati Metropolitan Area (GMA) is one such urban centre. The present study assesses the trajectories of LULC change using Landsat imageries acquired in 1976, 1989, 2002 and 2015. Natural and semi natural vegetated area and artificial and natural water bodies decreased while built-up areas, cultivated and managed areas, and natural and semi natural non-vegetated areas increased. The built-up area increased from 23.9 in 1976 to 115.1 km² in 2015 becoming the dominant land cover class accounting for 41.8% of the total geographical area. During this period, natural and semi natural vegetated land were reduced by 88.9 km² at an annual rate of 2.2 km². Over the years there was an increasing trend of built-up land and cultivated and managed areas in the peripheral areas of the city while natural and semi natural vegetated land diminished. Consequently, as in many other developing countries, there is an urgent need for the governmental authorities and other stakeholders to implement effective urban planning policies.     

Mapping land cover changes in Mexico, 1976–2000 and applications for guiding environmental management policy

Land use conversion typically implicates deforestation and fragmentation of primary land cover types, which invariably translates into impoverishment of both natural and cultural capital. Understanding where conversion is taking place crucially underpins sound environmental policy instruments to prevent these enormous social and economic costs. This paper examines 30 years of semi‐detailed (1:250 000) land cover mapping in Mexico. Pre‐existing analogue databases describing land cover patterns in the 1970s and 1990s were reviewed, corrected, reorganized and transformed into a digital format. Current land cover patterns were depicted by conducting updated reinterpretation on Landsat ETM+ imagery. Digital cartographic overlaying was performed and the results were used to construct a spatially explicit land use/land cover change (LULCC) database with an additional accuracy assessment procedure. The value of the results of this analysis is also seen in the light of their direct applications for identifying critical watershed trends, for guiding the allocation of financial funds for sound land use planning and for assessing the effectiveness of established protected areas. This effort highlights the importance of new and more effective geographical approaches to depict, understand and contribute to informed measures to mitigate ongoing negative trends in land cover and climatic changes.     

黄土高原春季降水对青藏高原感热异常的响应

利用1961—2000年黄土高原56站的春季降水和NCEP/NCAR再分析资料,采用SVD方法分析了黄土高原春季降水与青藏高原地面感热的关系。结果表明,黄土高原春季降水量与青藏高原地面感热的前两个模态代表了两场间的主要耦合特征,具有高度的时空相关。青藏高原感热对黄土高原降水影响最显著的区域在西部和南部、北部。前期高原感热场的第一、二模态对黄土高原春季干旱的预测具有指示意义。