Century‐long records reveal slight,ecoregion‐localized changes in Athabasca River flows          下载免费PDF全文

Stewart B. Rood  Geoff W. Stupple  Karen M. Gill 《水文研究》2015,29(5):805-816

Reports of abruptly declining flows of Canada's Athabasca River have prompted concern because this large, free‐flowing river could be representative for northern North America, provides water for the massive Athabasca oil‐sands projects and flows to the extensive and biodiverse Peace–Athabasca, Slave and Mackenzie River deltas. To investigate historic hydrology along the river and its major tributaries, we expanded the time series with interpolations for short data gaps; calculations of annual discharges from early, summer‐only records; and by splicing records across sequential hydrometric gauges. These produced composite, century‐long records (1913–2011) and trend detection with linear Pearson correlation provided similar outcomes to nonparametric Kendall τ‐b tests. These revealed that the mountain and foothills reaches displayed slight increases in winter discharges versus larger declines in summer discharges and consequently declining annual flows (~0.16% per year at Hinton; p < 0.01). Conversely, with contrasting boreal contributions, the Athabasca River at Athabasca displayed no overall trend in monthly or annual flows, but there was correspondence with the Pacific Decadal Oscillation that contributed to a temporary flow decline from 1970 to 2000. These findings from century‐long records contrast with interpretations from numerous shorter‐term studies and emphasize the need for sufficient time series for hydrologic trend analyses. For Northern Hemisphere rivers, the study interval should be at least 80 years to span two Pacific Decadal Oscillation cycles and dampen the influence from phase transitions. Most prior trend analyses considered only a few decades, and this weakens interpretations of the hydrologic consequences of climate change. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Elevation‐dependent responses of streamflow to climate warming          下载免费PDF全文

Christopher J. Tennant  Benjamin T. Crosby  Sarah E. Godsey 《水文研究》2015,29(6):991-1001

Warming will affect snowline elevation, potentially altering the timing and magnitude of streamflow from mountain landscapes. Presently, the assessment of potential elevation‐dependent responses is difficult because many gauged watersheds integrate drainage areas that are both snow and rain dominated. To predict the impact of snowline rise on streamflow, we mapped the current snowline (1980 m) for the Salmon River watershed (Idaho, USA) and projected its elevation after 3 °C warming (2440 m). This increase results in a 40% reduction in snow‐covered area during winter months. We expand this analysis by collecting streamflow records from a new, elevation‐stratified gauging network of watersheds contained within high (2250–3800 m), mid (1500–2250 m) and low (300–1500 m) elevations that isolate snow, mixed and rain‐dominated precipitation regimes. Results indicate that lags between percentiles of precipitation and streamflow are much shorter in low elevations than in mid‐ and high‐elevation watersheds. Low elevation annual percentiles (Q₂₅ and Q₇₅) of streamflow occur 30–50 days earlier than in higher elevation watersheds. Extreme events in low elevations are dominated by low‐ and no‐flow events whereas mid‐ and high‐elevation extreme events are primarily large magnitude floods. Only mid‐ and high‐elevation watersheds are strongly cross correlated with catchment‐wide flow of the Salmon River, suggesting that changes in contributions from low‐elevation catchments may be poorly represented using mainstem gauges. As snowline rises, mid‐elevation watersheds will likely exhibit behaviours currently observed only at lower elevations. Streamflow monitoring networks designed for operational decision making or change detection may require modification to capture elevation‐dependent responses of streamflow to warming. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

A shift towards wetter and windier conditions in southern Sweden around the prominent solar minimum 2750 cal a BP          下载免费PDF全文

ANETTE MELLSTRÖM  NATHALIE VAN DER PUTTEN  RAIMUND MUSCHELER  RIXT DE JONG  SVANTE BJÖRCK 《第四纪科学杂志》2015,30(3):235-244

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云南腾冲青海湖泊沉积物物化参数的特点、环境意义及末次冰消期以来气候环境变化     

刘亚生  常凤琴  张虎才  牛洁  段立曾  李华勇  文新宇  吴汉 《第四纪研究》2015,35(4)

根据对云南腾冲青海湖泊沉积钻孔样品的粒度特征、总有机碳、碳酸盐、磁化率及年代学分析测试,探讨了各指标的变化特点及其环境指示意义,指出了云南高原湖泊沉积物化指标的特殊性及其变化特点.在此基础上,重建了云南腾冲地区末次冰消期(15830a B.P.)以来沉积环境与气候干湿变化历史.通过青海沉积物年代序列的重建和综合各物化参数分析得出,云南腾冲地区自15830a B.P.以来总体呈现冷湿-温湿-暖干-温和偏干的气候演变过程,并可分为4个阶段,即15830～12790a B.P.气候温凉偏湿;12790～4680a B.P.为温暖湿润期,湖泊水位高,气候湿暖,降水多;4680～312a B.P.气候特征呈现出从温湿到暖干气候逐渐演化,降水减少,湖泊水位下降;312a B.P.以来气候特征为前期温和湿润,后期具有暖干化特征,反映了近几十年来全球气候变暖导致的气候变化趋势并叠加了研究区人类活动对区域环境的影响.  相似文献   

近47 a来黑河流域的降水时空特征分析及预报评估   总被引：8，自引：3，他引：5       下载免费PDF全文

丁荣  王伏村  王静  梁俊宁 《中国沙漠》2009,29(2):335-341

 利用1960—2006年黑河流域13个气象站, 地面气温、降水等观测资料,对该流域降水的气候年代际特征及干旱变化的成因进行了初步分析。结果表明,该流域降水量,由于受地形地貌、海拔高度和不同尺度大气环流的影响,流域内降水分配极不均匀,南北差异很大, 呈现为东南多西北少, 但降水日数的年月分布和流域的地理分布与降水量分布基本一致。总体上变化均呈波动性上升状态。同时,对2000年承担黑河流域分水的预报任务中研制的黑河流域降水预报服务系统输出的24~48 h降水量预报过程的准确率进行了TS评分检验。证明该系统对黑河流域的降水具有较强的预报能力,预报产品在气象服务工作中有重要参考价值,同时也为今后的精细化预报业务工作打下了一定的基础。  相似文献   

云南1971—2006年暖冬的时空变化分析   总被引：1，自引：0，他引：1  

徐虹  余凌翔 《云南地理环境研究》2009,21(6):22-24,F0004

暖冬的频繁发生已经对农业生产、人类健康和生态系统产生直接的影响。根据云南省1971～2006年冬季平均气温观测资料，采用概率气候事件划分方法确定单站暖冬阈值和暖冬强度等级标准，得到全省逐年暖冬指数，分析云南省“暖”冬的变化趋势和分布特征。结果表明：云南省冬季普遍增暖，1971～2006年共出现13个暖冬年，暖冬年在时间分布上很不均匀，在1997年以后呈现明显变暖趋势。  相似文献   

1961-2004年宁夏极端气温变化趋势分析   总被引：4，自引：1，他引：3       下载免费PDF全文

陈晓光  Declan Conway  郑广芬  陈晓娟 《气候变化研究进展》2008,4(2):73-077

 利用1961-2004年宁夏逐日最高、最低气温资料，分析了宁夏44 a来最高、最低气温的变化趋势。结果表明：宁夏的最高、最低气温表现出了明显的变化趋势，最高气温＜0℃的日数减少，＞30℃的日数增加；在年平均最低气温升高的同时，极冷日数也在增加，相对于1961-1990年的平均值，20世纪90年代和21世纪最初的4 a年极冷日数分别增加了1.1 d和0.7 d，距平百分率分别达350%和275%。  相似文献   

1959-2003年中国天山积雪的变化     

杨青  崔彩霞  孙除荣  Ren Yiyong 《气候变化研究进展》2008,4(Z1)

Mcteorological data at 17 weather stations in the Tianshan Mountains from 1959 to 2003 were analyzed to explore the variations in temperature and snow cover.The abrupt change test for snow depth was performed using Mann-Kendall statistic.The spatial distribution of maximum snow depth was calculated by employing GIDS interpolation and DEM data.The results show that mean temperature in winter had a rising trend at a rate of 0.44℃/10a.The minimum temperature in winter increased more evidently at a rate of 0.79℃/10a.The maximum snow depth has obviously deepened at a rate of 1.15 cm/10 a in the past 45 years,and it was about 16% higher than the average during 1991-2003.The Mann-Kendall statistic test of snow depth indicates that the abrupt change occurred in 1976.The maximum increment for snow cover depth occurred in Zhaoshu(Kunes)(39.3%)and Nilka(39.7%)in the west Tiansban Mountains.In contrast,the snow cover depth reduced by 17% in Barkol in the east Tianshan Mountains.There was a primary change periodicity of about 2.8 years in snow cover.In addition,snow cover days with a depth more than 10 cm increased distinctly,however,there was no obvious advance or delay in snow beginning and ending dates.  相似文献   

气候变化适应行动进展及对我国行动策略的若干思考     

居煇  韩雪 《气候变化研究进展》2008,4(5):257-260

 巴厘岛会议，即《联合国气候变化框架公约》（简称《公约》）第13次缔约方会议，明确了将气候变化适应和减缓并重的立场，并对适应工作进行了一系列的安排和部署。通过介绍《公约》下适应认识的发展过程，阐述了巴厘岛会议针对适应行动的一些进展，讨论了我国在适应方面可开展的行动和关注的领域。分析认为，目前适应已成为和减缓并重的关注议题，适应行动的呼声越来越强烈，但行动的落实还需要经过漫长的过程，适应基金募集和分配在发达国家和发展中国家之间、发展中国家内部也将有一个艰难而激烈的谈判交锋。  相似文献   

应对气候变化的国际技术协议评述   总被引：1，自引：1，他引：0  

裴卿  王灿  吕学都 《气候变化研究进展》2008,4(5):261-265

 国际技术协议通过促进技术的转让与升级，在发展中解决气候变化问题，因此受到越来越多的关注。根据"巴厘路线图"中的重要议题，在对国际技术协议进行简要介绍的基础上，评价了国际技术协议内在的价值与局限性。最后对国际技术协议的前景进行了展望，指出国际技术协议应当着眼于通过促进环境友好的先进技术由发达国家向发展中国家的转让，推动在应对气候变化领域内更深层次的南北合作，实现发展中国家的可持续发展，逐步解决气候变化问题。同时，为中国如何参与国际技术协议给出了建议。  相似文献