一种顾及异常区域的海温多尺度分区方法

空间聚类分析是空间数据挖掘的主要方法之一,旨在发现海量数据中潜在的空间分布模式和异常特征。此处采用空间聚类分析和多尺度分析相结合的策略对海温进行多尺度气候分区。首先,针对气候时间序列特征和异常区域特征,提出一种顾及异常区域的多尺度分区方法;进而,分别采用传统方法和新方法对海温进行多尺度气候分区,通过比较分析发现新方法更优越;最后,利用气候指数对分区结果进行验证,说明新方法是有效的。     

乌鲁木齐夏季强降水过程GPS-PWV的演变特征

利用乌鲁木齐GPS观测站数据反演得到1h间隔GPS遥测的大气可降水量(GPS-PWV)和乌鲁木齐自动气象站逐时降水资料,分析了乌鲁木齐地区夏季10次中雨以上降水过程的GPS-PWV演变特征。结果表明,乌鲁木齐地区的强降水过程中GPS-PWV呈现出明显的1～3天增湿过程和1～2次跃变过程,且降水时GPS-PWV几乎约为气候平均值的2倍,跃变过程与降水发生和结束有较好的关系,可为干旱区降水短期预报提供一个明确的水汽演变指标。     

Projection of Water Availability in the Miyun Watershed from an RCM Simulation

Based on a high-resolution regional climate model (RegCM3) simulation over East Asia, future climate changes over the Miyun Reservoir in the 21st century under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) A1B scenario are analyzed. The model simulation extends from 1951 to 2100 at a grid spacing of 25 km and is one-way nested within a global model of MIROC3.2_ hires (the Model for Interdisciplinary Research on Climate). The focus of the analysis is on the Watershed of Miyun Reservoir, the main water supply for Beijing in northern China. The results show that RegCM3 reproduces the observed temperature well but it overestimates precipitation over the region. Significant warming in the 21st century is simulated in the annual mean, December-January-February (DJF) and June-July-August (JJA), although with differences concerning the spatial distribution and magnitude. Changes in precipitation for the annual mean, DJF, and JJA also show differences. A prevailing increase of precipitation in DJF and a decrease of it in JJA is projected over the region, while little change in the annual mean is projected. Changes of the difference between precipitation and evapotranspiration to measure the potential water availability are also presented in the paper.     

基于多时相遥感图像智能变化检测方法的研究

采用一种智能变化检测方法,首先对多实相遥感图像进行预处理;其次进行特征提取;然后通过数量差异计算、阀值确定、空间滤波进行检测;最后提取出感兴趣的区域,得出定量结果,并通过试验证明这种方法在实际应用中是可行的和有效的。     

中国黄土高原塬区表层土壤水分盈缺状况的研究

陆地表层水分的盈缺直接关系到局地气候变化.本文利用黄土高原塬区初夏至盛夏期两次陆面过程野外试验(LOess Plateau land surface process field EXperiment 2005,LOPEX05和LOPEX06)的野外试验观测资料,分析了试验期间黄土高原白庙塬区不同下垫面的水分蒸散和表层土壤水分盈缺状况.结果表明:在土壤水分比较充足的条件下,植被蒸腾增加量在正午时的峰值为0.05 mm·h-1,而较大降水发生后的首个晴日.冬小麦地和裸地的蒸散分别可达4.60 mm·d-和3.70 mm·d-1.局地降水是影响陆面蒸散量变化的主要因素,而植被冠层的存在增加了陆面蒸散发量中的植物蒸腾量值.2006年4月下旬到7月中旬,裸地的水分缺失为16.3 mm·m2,冬小麦地的水分缺失为39.9mm·m2.其中缺失最严重的时间段为5月下旬到6月上旬,最大旬缺失量达16.5 mm·m2,7月上旬和中旬,由于降水季节来临,土壤水分有少量盈余.在2005年7月中旬至8月下旬,玉米地和裸地的水分盈余分别为17.9 mm·m2和25.3 mm·m2.不同时间尺度的统计均表明,降水不仅是影响陆面蒸散量的主要因素,而且也是表层土壤水分盈缺的决定性因子.     

黑龙江省短时暴雨天气分型及雷达回波特征

通过统计黑龙江省2005～2006年260个短时暴雨样本,结合天气图和雷达图进行分析,对黑龙江省短时暴雨分类,并总结出不同天气形势下短时暴雨的雷达回波特征.     

Impacts of the Three Gorges Reservoir on its immediate downstream hydrological drought regime during 1950–2016

Natural Hazards - Impacts of the Three Gorges Reservoir (TGR) on the downstream hydrological extremes always draw public attentions, particularly during its (quasi) normal water storing period. To...     

Cyclostratigraphic Calibration of the Upper Ordovician (Sandbian–Katian) Pagoda and Linhsiang Formations in the Yichang Area, South China

正1 Introduction The Sandbian-Katian is a critical period for the transition from"hot-house"in the Lower Ordovician to"ice-house"in the end-Ordovician (Trotter et al.,2008).During this interval,the South China Block was located in the equatorial region (Torsvik and Cocks,2016),with the widespread accumulation of Pagoda and Linhsiang formations (Zhan and Jin,2007).Although these strata have been investigated for decades and their     

Towards Regional Synergy: Reconciling Rangeland Ecological Functioning with Forage Production of Cultivated Pasture

Animal husbandry and crop farming are specialized for development in separate areas on the Tibetan Plateau. Such a pattern of isolation has led to current concerns of rangeland and farming system degradation due to intensive land use. The crop-livestock integration, however, has been proven to increase food and feed productivity thorough niche complementarity, and is thereby especially effective for promoting ecosystem resilience. Regional synergy has emerged as an integrated approach to reconcile rangeland livestock with forage crop production. It moves beyond the specialized sectors of animal husbandry and intensive agriculture to coordinate them through regional coupling. Therefore, crop-livestock integration (CLI) has been suggested as one of the effective solutions to forage deficit and livestock production in grazing systems. But it is imperative that CLI moves forward from the farm level to the regional scale, in order to secure regional synergism during agro-pastoral development. The national key R & D program, Technology and Demonstration of Recovery and Restoration of Degraded Alpine Ecosystems on the Tibetan Plateau, aims to solve the problems of alpine grassland degradation by building up a grass-based animal husbandry technology system that includes synergizing forage production and ecological functioning, reconciling the relationship between ecology, forage production and animal husbandry, and achieving the win-win goals of curbing grassland degradation and changing the development mode of animal husbandry. It is imperative to call for regional synergy through integrating ecological functioning with ecosystem services, given the alarming threat of rangeland degradation on the Tibetan Plateau. The series of papers in this issue, together with those published previously, provide a collection of rangeland ecology and management studies in an effort to ensure the sustainable use and management of the alpine ecosystems.