Precipitable water conversion rates over the Qinghai‐Xizang (Tibet) Plateau: changing characteristics with global warming     

Chenghai Wang  Yipeng Guo 《水文研究》2012,26(10):1509-1516

In this article, the trends and variability of precipitation and precipitable water (PW) over the Qinghai‐Xizang (Tibet) Plateau (QXP) (1970–2009) were analysed by using ERA‐40 (The European Center for Medium‐Range Weather Forecasts (ECMWF) 40 years Re‐analysis) and NCEP (The National Centers for Environmental Prediction)/NCAR reanalyses data and the ground observed precipitation data from 60 sites. The results showed that the precipitation over the QXP had an overall increasing trend; however, a slight decreasing trend was observed over the southeast. This decreasing precipitation trend might be related to the South Asia monsoon degradation. Since 1970, a decreasing PW trend has occurred over the QXP in which the southeast is the most significant region. Because of the rising temperatures in the QXP, a remarkable PW conversion rate (PWCR) increase of 0.87% per decade has occurred over the past 40 years. Because of its steep terrain, the PWCR in the middle eastern region of the QXP increased faster than that of the other regions. The mean PWCR in the wet southern region of the QXP was higher than that of the dry northern region, which was higher in the winter than that in the summer. Although much precipitation occurred in the summer, in the wet regions, the PWCR was higher in the winter than in the summer. The PWCR peak in the wet and dry regions occurred during the precipitation‐short and precipitation‐sufficient seasons, respectively. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Influence of land use/land cover (LULC) changes on atmospheric dynamics over the arid region of Rajasthan state,India     

《Journal of Arid Environments》2013

The present study examines the long-term effects of land use/land cover (LULC) changes in Rajasthan state, India on land-atmosphere fluxes and, possibly in precipitation and aerosol loading. By comparing the satellite observations from Landsat MSS (1972–73) and IRS-P6 AWiFS (2006–07) considerable LULC changes are observed, an increase in crop-land and vegetated areas of ∼57% in the eastern and ∼68% in the western Rajasthan. The increase in agriculture intensification from irrigation activities after the construction of the Indira Gandhi canal (IGC) seems to affect the land-atmosphere fluxes, i.e. increase in atmospheric humidity and latent heat and reduction in sensible heat. On the other hand, the multi-decadal variability (1951–2007) in annual rainfall amount and total number of rainy days reveals significant year-to-year fluctuations, exhibiting a slight increasing trend over arid western Rajasthan. However, the overall analysis shows that the variability in precipitation is much more influenced by the general monsoonal circulation (i.e. meteorological dynamics and intensity of the monsoon) and partly can be associated with local phenomena, such as LULC changes and modifications in land-atmosphere fluxes. Similarly to precipitation, the long-term (1979–2008) aerosol index (AI) variations over the region seem to be affected by atmospheric and meteorological dynamics and not by LULC changes.  相似文献   

Glacial/interglacial sea surface temperature changes in the Southwest Pacific ocean over the past 360 ka     

Kazuyo Tachikawa  Laurence Vidal  Corinne Sonzogni  Edouard Bard 《Quaternary Science Reviews》2009,28(13-14):1160-1170

The phase relationship between climate parameters during terminations gives insight into deglaciation mechanisms. By combining foraminiferal Mg/Ca and alkenone thermometers with planktonic and benthic foraminiferal δ¹⁸O, we determined the phase relationship between local sea surface temperature (SST) and global seawater δ¹⁸O changes in the Coral Sea in the Southwestern Pacific over the last 360 ka. The onset of the SST warming preceded the seawater δ¹⁸O change by several ka for Termination I, II and III. During Termination I, the SST warming started at 20 ka BP, earlier than atmospheric CO₂ rise suggesting that the greenhouse effect was not the main trigger of this early warming. Compilation of ¹⁴C-dated SST records from the whole Pacific during Termination I reveals that the onset of the warming is generally earlier in the Southern and the tropical Pacific than in the North Pacific. This spatio-temporal warming pattern suggests linkage between the southern ocean and tropical Pacific. The early tropical warming could provide heat and moisture to the northern high latitudes, modifying radiative balance and precipitation over ice sheets at the onset of deglaciation.  相似文献   

Social equity and the probability of success of biodiversity conservation     

《Global Environmental Change》2015

Conservation actions generally benefit some groups more than others, and this inequity is thought to affect the probability of achieving conservation objectives. This has led to the common assumption that triple bottom line solutions – those that are effective, efficient, and equitable – are best and most likely to achieve each individual objective. Although this may be true, it has been little tested, and importantly lacks a conceptual foundation for understanding, predicting and evaluating how equity affects conservation outcomes. We describe types of equity relevant to conservation and explore how they may affect the probability of successfully achieving conservation outcomes. Depending on the equity type and context, the relationship between equity and conservation success varies. We find that the best conservation outcome is often achieved without perfect equity; highlighting the risk of ignoring the relationship between equity and success. We offer a conceptual foundation for better addressing this important issue in future research and application.  相似文献   

Improvements in the representation of the Indian summer monsoon in the NCEP climate forecast system version 2     

Rodrigo J. Bombardi  Edwin K. Schneider  Lawrence Marx  Subhadeep Halder  Bohar Singh  Ahmed B. Tawfik  Paul A. Dirmeyer  James L. Kinter III 《Climate Dynamics》2015,45(9-10):2485-2498

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A Bayesian model of factors influencing indigenous participation in the Torres Strait tropical rocklobster fishery     

《Marine Policy》2013

The tropical rocklobster fishery in the Torres Strait, based on the species Panulirus ornatus, is currently managed by input controls. The Australian Commonwealth government’s aim is to transition to a quota management system (QMS) for this fishery. The fishery is complex in terms of international boundaries, multiple jurisdictions and management objectives regulating a mix of commercial and traditional indigenous fishers and a commercial non-indigenous sector. One key objective is to promote indigenous fisher participation to meet their aspirations of achieving a greater control of the region’s fisheries resources. A Bayesian Network analysis has been applied that considers the variability in participation of indigenous fishers under key economic and socio-cultural drivers, such as the availability of a government employment program, lobster prices, social capital and capacity, and infrastructure availability. The model identifies three distinct indigenous fisher groups: full-time, active part-time, and casual lobster fishers. Scenario analyses suggest that changes in the government employment program will have a substantial impact on the relative proportion of fishers in these groups. Similarly, changes in the provision of logistics, infrastructure, and building social capital and capacity are expected to have a significant impact on the occurrence of full-time fishing. As the Commonwealth has an obligation under the Torres Strait Treaty to protect the traditional way of life and livelihood of Islanders as well as promoting employment opportunities for Traditional Inhabitants, it is important that management authorities consider both the effect of management changes for the fishery as a whole and for each indigenous fisher group separately.  相似文献   

International workshop on methodological evolution to improve estimates of life history parameters and fisheries management of data-poor deep-water snappers and groupers     

《Marine Policy》2015

Knowledge of both the life history characteristics and catch and effort statistics of exploited deep-water fishes such as snappers and groupers is typically limited. This contributes to increased uncertainty in stock assessments and, depending on the diligence in governance, is more likely to result in either highly conservative or unsustainable management arrangements. Developments, challenges and advances in the methods for obtaining life history data for these species were discussed at a workshop in May 2015. The key points raised included nascent methods for otolith sectioning and interpretation, the need for standardised international ageing protocols and the issues and challenges in characterising reproductive maturation, including during non-spawning months due to resource limitations. Strategic research directions are identified to address knowledge gaps and thus better inform fisheries management.  相似文献   

CLM4.5模式对青藏高原土壤湿度的数值模拟及评估     

袁源  赖欣  巩远发  文军  丁旭  朱丽华  张永莉  王炳赟  王欣  王作亮  孟宪红  陈金雷 《大气科学》2019,43(3):676-690

本文利用1981～2016年的CRUNCEP资料（0.5°×0.5°）作为大气驱动数据,驱动CLM4.5（Community Land Model version 4.5）模式模拟了青藏高原地区1981～2016 年的土壤湿度时空变化。将模拟数据与台站观测资料、再分析资料（ERA-Interim和GLDAS-CLM）和微波遥感FY-3B/MWRI土壤湿度资料对比验证,表明了CLM4.5模拟资料可以合理再现青藏高原地区土壤湿度的空间分布和长期变化趋势。而且基于多种卫星遥感资料建立的较高分辨率（0.1°×0.1°）的青藏高原地表数据更加细致地刻画了土壤湿度的空间变化。对比结果表明:CLM4.5模拟土壤湿度与各个台站观测的时空变化一致,各层土壤湿度的模拟和观测均显著相关,且对浅层的模拟优于深层,但模拟结果比台站观测系统性偏大。模拟与再分析资料和微波遥感资料土壤湿度的空间分布具有一致性,均表现为从青藏高原的西北部向东南部逐渐增加的分布特点,三江源湿地和高原东南部为土壤湿度的高值区,柴达木盆地和新疆塔里木盆地的沙漠地区为低值区,土壤湿度由浅层向深层增加。土壤湿度的长期变化趋势基本表现为“变干—变湿”相间的带状分布,不同层次的土壤湿度变化趋势基本一致。模拟资料也合理地再现了夏季土壤湿度逐月的变化:高原西南地区的土壤湿度明显大范围增加,北部的柴达木盆地的干旱范围也明显的向北收缩,高原南部外围土壤湿度也明显增加,CLM4.5模拟土壤湿度比再分析资料和微波遥感资料更加细致地描述了夏季逐月土壤湿度空间分布及其变化特征。  相似文献   

地基微波遥感评估黄河源区草原下垫面土壤冻融过程研究     

蒋雨芹  文军  吕少宁  王作亮  刘闻慧  武月月  邓浩 《冰川冻土》2021,43(6):1718-1731

土壤冻融过程对气候变化非常敏感,如何准确监测土壤冻融过程具有重要的科学意义。利用2017年6月至2018年6月中国科学院若尔盖高原湿地生态系统研究站玛曲观测场地基微波辐射计观测数据、浅层土壤温度和近地面气温数据,通过构建归一化极化比值冻结因子、极化差值冻结因子、组合水平极化差值冻结因子和组合垂直极化差值冻结因子等不同土壤冻结因子,评估了黄河源区草原下垫面土壤冻融过程。结果表明：L波段微波辐射计监测土壤冻融状态的结果与近地面气温和浅层土壤温度表征的土壤冻融过程基本一致。当入射角为50°时,归一化极化比值冻结因子和极化差值冻结因子与实测数据的一致性分别达到83.6%和82.8%。每种冻结因子具有明显的季节性变化,四种冻结因子在春季时的准确度低于夏、秋、冬三个季节。归一化后的相对冻结因子的标准差在秋季最大,可达0.3;在冬季和夏季最小,值小于0.2。在土壤发生冻结和融化转换时,垂直极化和水平极化下的亮温同时下降,其差值较完全冻结或者完全融化时的亮温差大。研究结果可为微波遥感监测土壤冻融过程提供技术参考。  相似文献   

春季热带海温与北疆夏季极端降水的关系研究   总被引：1，自引：0，他引：1  

周雅蔓  刘晶  赵勇  马超  李娜 《冰川冻土》2021,43(4):1166-1178

基于1961—2017年北疆47站夏季逐日降水资料、NOAA海温资料和NCEP/NCAR再分析资料,利用90%分位确定北疆夏季单站降水阈值,得出极端降水量,讨论了春季热带海温与北疆夏季极端降水的关系。结果表明：北疆夏季极端降水和春季热带印度洋（20° S~15° N,50°~110° E）及赤道东太平洋（15° S~15° N,90°~180° W）海温呈正相关,两个关键区春季热带海温异常偏暖时,北疆夏季极端降水偏多,仅春季热带印度洋关键区海温异常偏暖时,北疆西北地区夏季极端降水偏多。当春季热带印度洋和赤道东太平洋关键区海温同时异常偏暖时,200 hPa西风急流轴明显偏南,500 hPa西西伯利亚和中亚地区低值系统活跃,南方路径输送的水汽增加,有利于北疆夏季极端降水的发生;仅春季热带印度洋关键区海温异常偏暖时,200 hPa西风急流强度增强,500 hPa西西伯利亚地区低值系统活跃,配合偏东路径的水汽输送,北疆西北地区夏季极端降水偏多。  相似文献