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1.
Changes in Canada's Climate: Trends in Indices Based on Daily Temperature and Precipitation Data 总被引：1，自引：0，他引：1
ABSTRACTTrends in indices based on daily temperature and precipitation are examined for two periods: 1948–2016 for all stations in Canada and 1900–2016 for stations in the south of Canada. These indices, a number of which reflect extreme events, are considered to be impact relevant. The results show changes consistent with warming, with larger trends associated with cold temperatures. The number of summer days (when daily maximum temperature >25°C) has increased at most locations south of 65°N, and the number of hot days (daily maximum temperature >30°C) and hot nights (daily minimum temperature >22°C) have increased at a few stations in the most southerly regions. Very warm temperatures in both summer and winter (represented by the 95th percentile of their daily maximum and minimum temperatures, respectively) have increased across the country, with stronger trends in winter. Warming is more pronounced for cold temperatures. The frost-free season has become longer with fewer frost days, consecutive frost days, and ice days. Very cold temperatures in both winter and summer (represented by the 5th percentile of their daily maximum and minimum temperatures, respectively) have increased substantially across the country, again with stronger trends in the winter. Changes in other temperature indices are consistent with warming. The growing season is now longer, and the number of growing degree-days has increased. The number of heating degree-days has decreased across the country, while the number of cooling degree-days has increased at many stations south of 55°N. The frequency of annual and spring freeze–thaw days shows an increase in the interior provinces and a decrease in the remainder of the country. Changes in precipitation indices are less spatially coherent. An increase in the number of days with rainfall and heavy rainfall is found at several locations in the south. A decrease in the number of days with snowfall and heavy snowfall is observed in the western provinces, while an increase is found in the north. There is no evidence of significant changes in the annual highest 1-day rainfall and 1-day snowfall. The maximum number of consecutive dry days has decreased, mainly in the south. 相似文献
2.
华中地区2030年前气温和降水量变化预估 总被引：3，自引：0，他引：3
根据区域气候模式对华中地区1961-1990年和2001-2030年的逐月平均气温和降水量的模拟值（0.5°×0.5°经纬度格点,A2情景）,以1961-1990年为基准,计算并分析了该区域未来30 a（2001-2030年）的年、季平均气温和降水量的变化趋势。对气温变化而言,未来30 a华中地区年平均气温呈上升趋势,平均升温0.3℃,东部增温大于西部;春、夏季平均气温上升,分别为0.1～1.3℃、0.8～2.2℃;秋季北部地区气温下降,南部地区气温升高;冬季平均气温下降0.0～1.0℃。就降水而言,未来30 a华中地区年平均降水量大部分地区呈减少趋势,空间分布有南增北减的特点;春、夏、冬季平均降水量大部分地区减少,冬季平均降水量的减幅要大于春、夏季;秋季大部分地区平均降水量增加。 相似文献
3.
根据区域气候模式对华中地区1961-1990年和2001-2030年的逐月平均气温和降水量的模拟值（0.5°×0.5°经纬度格点,A2情景）,以1961-1990年为基准,计算并分析了该区域未来30 a（2001-2030年）的年、季平均气温和降水量的变化趋势。对气温变化而言,未来30 a华中地区年平均气温呈上升趋势,平均升温0.3℃,东部增温大于西部;春、夏季平均气温上升,分别为0.1～1.3℃、0.8～2.2℃;秋季北部地区气温下降,南部地区气温升高;冬季平均气温下降0.0～1.0℃。就降水而言,未来30 a华中地区年平均降水量大部分地区呈减少趋势,空间分布有南增北减的特点;春、夏、冬季平均降水量大部分地区减少,冬季平均降水量的减幅要大于春、夏季;秋季大部分地区平均降水量增加。 相似文献
4.
Long-term variability of occurrence of precipitation forms in winter in Kraków, Poland 总被引：1，自引：0，他引：1
Robert Twardosz Ewa ?upikasza Tadeusz Nied?wied? Adam Walanus 《Climatic change》2012,113(3-4):623-638
The paper discusses long-term change in snowfall, rainfall and mixed precipitation viewed in conjunction with air temperature and North Atlantic Oscillation (NAO) in winter (December–February). In the study of contemporary climate change and its effect on the hydrological cycle it is useful to focus on winter precipitation forms. A 146-year secular observation series from Kraków, spanning the period 1863–2008, was used to extract data on the number of days with precipitation and on precipitation amount broken down by form. Statistically significant trends were found in total and mixed precipitation, but not in snowfall and rainfall. The climate warming effect has contributed to a material decrease in the snowfall to total winter precipitation ratio during the second half of the 20th c. The highest impact of air temperature was found in the wintertime variation in number of days with snowfall while the NAO had a significant influence on the frequency and amount of both rainfall and snowfall. 相似文献
5.
Spatial dependence of diurnal temperature range trends on precipitation from 1950 to 2004 总被引：2，自引：0，他引：2
Liming Zhou Aiguo Dai Yongjiu Dai Russell S. Vose Cheng-Zhi Zou Yuhong Tian Haishan Chen 《Climate Dynamics》2009,32(2-3):429-440
This paper analyzes the spatial dependence of annual diurnal temperature range (DTR) trends from 1950–2004 on the annual climatology of three variables: precipitation, cloud cover, and leaf area index (LAI), by classifying the global land into various climatic regions based on the climatological annual precipitation. The regional average trends for annual minimum temperature (T min) and DTR exhibit significant spatial correlations with the climatological values of these three variables, while such correlation for annual maximum temperature (T max) is very weak. In general, the magnitude of the downward trend of DTR and the warming trend of T min decreases with increasing precipitation amount, cloud cover, and LAI, i.e., with stronger DTR decreasing trends over drier regions. Such spatial dependence of T min and DTR trends on the climatological precipitation possibly reflects large-scale effects of increased global greenhouse gases and aerosols (and associated changes in cloudiness, soil moisture, and water vapor) during the later half of the twentieth century. 相似文献
6.
Global climate models predict that terrestrial northern high-latitude snow conditions will change substantially over the twenty-first century. Results from a Community Climate System Model simulation of twentieth and twenty-first (SRES A1B scenario) century climate show increased winter snowfall (+10–40%), altered maximum snow depth (?5 ± 6 cm), and a shortened snow-season (?14 ± 7 days in spring, +20 ± 9 days in autumn). By conducting a series of prescribed snow experiments with the Community Land Model, we isolate how trends in snowfall, snow depth, and snow-season length affect soil temperature trends. Increasing snowfall, by countering the snowpack-shallowing influence of warmer winters and shorter snow seasons, is effectively a soil warming agent, accounting for 10–30% of total soil warming at 1 m depth and ~16% of the simulated twenty-first century decline in near-surface permafrost extent. A shortening snow season enhances soil warming due to increased solar absorption whereas a shallowing snowpack mitigates soil warming due to weaker winter insulation from cold atmospheric air. Snowpack deepening has comparatively less impact due to saturation of snow insulative capacity at deeper snow depths. Snow depth and snow-season length trends tend to be positively related, but their effects on soil temperature are opposing. Consequently, on the century timescale the net change in snow state can either amplify or mitigate soil warming. Snow state changes explain less than 25% of total soil temperature change by 2100. However, for the latter half of twentieth century, snow state variations account for as much as 50–100% of total soil temperature variations. 相似文献
7.
A second generation adjusted precipitation daily dataset has been prepared for trend analysis in Canada. Daily rainfall and snowfall amounts have been adjusted for 464 stations for known measurement issues such as wind undercatch, evaporation and wetting losses for each type of rain-gauge, snow water equivalent from ruler measurements, trace observations and accumulated amounts from several days. Observations from nearby stations were sometimes combined to create time series that are longer; hence, making them more useful for trend studies. In this new version, daily adjustments are an improvement over the previous version because they are derived from an extended dataset and enhanced metadata knowledge. Datasets were updated to cover recent years, including 2009. The impact of the adjustments on rainfall and snowfall total amounts and trends was examined in detail. As a result of adjustments, total rainfall amounts have increased by 5 to 10% in southern Canada and by more than 20% in the Canadian Arctic, compared to the original observations, while the effect of the adjustments on snowfall were larger and more variable throughout the country. The slope of the rain trend lines decreased as a result of the larger correction applied to the older rain-gauges while the slope of the snow trend lines increased, mainly along the west coast and in the Arctic. Finally, annual and seasonal rainfall and snowfall trends based on the adjusted series were computed for 1950–2009 and 1900–2009. Overall, rainfall has increased across the country while a mix of non-significant increasing and decreasing trends was found during the summer in the Canadian Prairies. Snowfall has increased mainly in the north while a significant decrease was observed in the southwestern part of the country for 1950–2009. 相似文献
8.
Leo Šeparović Adelina Alexandru René Laprise Andrey Martynov Laxmi Sushama Katja Winger Kossivi Tete Michel Valin 《Climate Dynamics》2013,41(11-12):3167-3201
The fifth-generation Canadian Regional Climate Model (CRCM5) was used to dynamically downscale two Coupled Global Climate Model (CGCM) simulations of the transient climate change for the period 1950–2100, over North America, following the CORDEX protocol. The CRCM5 was driven by data from the CanESM2 and MPI-ESM-LR CGCM simulations, based on the historical (1850–2005) and future (2006–2100) RCP4.5 radiative forcing scenario. The results show that the CRCM5 simulations reproduce relatively well the current-climate North American regional climatic features, such as the temperature and precipitation multiannual means, annual cycles and temporal variability at daily scale. A cold bias was noted during the winter season over western and southern portions of the continent. CRCM5-simulated precipitation accumulations at daily temporal scale are much more realistic when compared with its driving CGCM simulations, especially in summer when small-scale driven convective precipitation has a large contribution over land. The CRCM5 climate projections imply a general warming over the continent in the 21st century, especially over the northern regions in winter. The winter warming is mostly contributed by the lower percentiles of daily temperatures, implying a reduction in the frequency and intensity of cold waves. A precipitation decrease is projected over Central America and an increase over the rest of the continent. For the average precipitation change in summer however there is little consensus between the simulations. Some of these differences can be attributed to the uncertainties in CGCM-projected changes in the position and strength of the Pacific Ocean subtropical high pressure. 相似文献
9.
Glaciers of the conterminous United States have been receding for the past century. Since 1900 the recession has varied from a 24 % loss in area (Mt. Rainier, Washington) to a 66 % loss in the Lewis Range of Montana. The rates of retreat are generally similar with a rapid loss in the early decades of the 20th century, slowing in the 1950s–1970s, and a resumption of rapid retreat starting in the 1990s. Decadal estimates of changes in glacier area for a subset of 31 glaciers from 1900 to 2000 are used to test a snow water equivalent model that is subsequently employed to examine the effects of temperature and precipitation variability on annual glacier area changes for these glaciers. Model results indicate that both winter precipitation and winter temperature have been important climatic factors affecting the variability of glacier variability during the 20th Century. Most of the glaciers analyzed appear to be more sensitive to temperature variability than to precipitation variability. However, precipitation variability is important, especially for high elevation glaciers. Additionally, glaciers with areas greater than 1 km2 are highly sensitive to variability in temperature. 相似文献
10.
采用东英吉利大学气候研究中心（CRU）提供的月地表温度和降水资料,分析了全球年平均及冬季地表温度变化趋势,发现在北半球中高纬地区半干旱区冬季快速增温。在此基础上通过分析帕默尔干旱指数（PDSI）研究了北美和欧亚大陆冬季地表干湿变化的时空特征和差异,并讨论北美和欧亚大陆冬季快速增温对地表干湿变化的影响。结果表明,北美大陆南部微弱变湿,加拿大北极群岛变湿明显,而在北美大陆的中西部有明显的变干趋势;欧亚大陆大部分地区在冬季有一定的变干趋势,其中尤以西欧南部,中国华北、东北,蒙古中北、东北部及俄罗斯远东地区变干最为显著。但北美和欧亚大陆1950-2008年冬季降水并无显著变化趋势,地表干湿变化主要受气温的影响,尤其是在冬季增温最为快速的地区。 相似文献
11.
为了全面把握20世纪80年代以来中国生态脆弱区气候变化的特征,利用基于全国2000多个站点的格点化逐月资料,对中国典型生态脆弱区1980～2014年的日平均气温、日最高和最低气温、降水、相对湿度、风速和蒸发皿蒸发量的变化特征进行了分析。结果表明:（1）中国生态脆弱区日平均气温、日最高和最低气温几乎都呈上升趋势;日平均气温增幅北方大于南方;北方生态脆弱区日平均气温、日最高和最低气温、南方生态脆弱区日最低气温的季节增幅多为春季最大,秋季或冬季最小。（2）全区平均降水变化趋势不明显;生态脆弱区降水距平百分率春季多为增长趋势,夏季多为减少趋势,秋、冬季和年北方多为增长趋势,南方多为减少趋势。（3）相对湿度以减少趋势为主,只有黄土高原南部脆弱区秋、冬季和干旱半干旱区脆弱区冬季相对湿度距平百分率的趋势为正,这几个正值区同时也是降水增长大值区。（4）风速基本为减少趋势,春季减少趋势最大。（5）全区平均蒸发皿蒸发量春、夏季和年为减少趋势,冬季为增长趋势;北方生态脆弱区蒸发皿蒸发量四季和年多呈减少趋势;南方生态脆弱区蒸发皿蒸发量春、夏季以减少趋势为主,秋、冬季和年呈增长趋势。 相似文献
12.
利用喜马拉雅山脉中段南、北两侧6个气象站1971-2007年逐月气温、降水资料,分析了该地区气候变化趋势、异常及突变特征。结果表明：喜马拉雅山脉中段南、北两侧年、季平均气温均呈明显上升趋势,冬半年升温幅度大于夏半年。年及夏半年平均气温均为随年代升高趋势,而冬半年气温在20世纪80年代较70年代略偏低,90年代后又逐渐升高。21世纪前7 a升温最为显著,较20世纪70年代升高0.6～1.1℃。1997年该地区南侧年平均气温发生突变,突变后增温趋势更加明显。20世纪90年代末以来,异常偏暖年份出现的几率明显增加,且南侧多于北侧。喜马拉雅山脉中段北侧年及冬夏半年降水均呈增多趋势。南侧年和夏半年降水呈减少趋势,冬半年为增多趋势。降水异常出现在20世纪80、90年代,21世纪后降水出现异常的概率明显减少。近40 a,北侧气候具有暖湿化趋势;南侧冬半年与之类似,但夏半年及全年呈暖干化趋势。 相似文献
13.
P. V. Novorotskii 《Russian Meteorology and Hydrology》2007,32(2):102-109
Tendencies in climate change in the Amur River basin are generally synchronous to the global ones. During the last century, the annual mean temperature of surface air increased by 1.3°C, minimum warming being observed in the east part of the basin (0.6°C) and maximum one in the west part (1.7–2.5°C). The largest impact on the annual mean temperature growth comes from winter and spring temperature increase (2–4°C/100 years). During the last 30 years, the warming rate in the basin was 2–3 times higher than during the whole period of 1891–2004. Simultaneously with warming in the Amur River basin, annual and warm-season precipitation totals increased by 8 and 6%, respectively, during the 115-year period. The highest increase in precipitation totals occurs in cold season (29% during 115 years). During the last 30 years, together with intense warming in the Amur River basin, the annual precipitation totals are found to decrease by an average of 2.1%/10 years. 相似文献
14.
青海南部地区初冬雪灾变化及环流特征 总被引：3，自引：1，他引：2
利用青海南部地区1961~2004年气温、降水、积雪等资料,分析了初冬雪灾变化及环流特征。结果表明:青海南部地区初冬降雪量呈缓慢减少的变化趋势,平均积雪量变化与年及其它季相比,呈微弱的减少趋势,平均积雪量与气温呈反相关,而与降雪量呈正相关;影响青海南部地区初冬降雪的主要天气系统是西风带南北槽结合类、移动性高原槽类、高原低涡类、高原切变类、孟加拉湾风暴类;典型多雪(少雪)年高原及南亚与中亚地区850 hPa温度距平场配置为“南正北负”(“南负北正”)型5、00 hPa高原与东部沿海地区距平分布为“西低东高”(“西高东低”)型。 相似文献
15.
近50年中国气温日较差的变化趋势分析 总被引：23，自引：2，他引：23
利用近50年的气温观测资料,对中国地区的气温日较差的空间分布和时间序列变化特征进行了分析。同时分析了与日最高气温、最低气温以及平均气温时空分布之间的关系。结果发现,近50年来气温日较差呈下降趋势,其平均减小幅度为高纬度地区大于低纬度地区;不同地区及同一地区的DTR季节变化特征也不相同,我国北方多为冬季DTR下降最大,其次是春季和秋季,夏季最小。在黄淮和长江流域,以夏季和春季DTR下降最为显著。华南地区仍以冬季下降最大。气温日较差整体呈现下降趋势,中高纬度下降比低纬度明显。在相同纬度带上,由于地理状况的不同,变化趋势有所不同。同时,气温日较差的变化有明显的区域和季节性差异,特别在西部的青藏高原和新疆地区的DTR变化与东部地区的差异明显。 相似文献
16.
Permafrost Thaw Accelerates in Boreal Peatlands During Late-20th Century Climate Warming 总被引：7，自引：0，他引：7
Philip Camill 《Climatic change》2005,68(1-2):135-152
Permafrost covers 25% of the land surface in the northern hemisphere, where mean annual ground temperature is less than 0°C. A 1.4–5.8 °C warming by 2100 will likely change the sign of mean annual air and ground temperatures over much of the zones of sporadic and discontinuous permafrost in the northern hemisphere, causing widespread permafrost thaw. In this study, I examined rates of discontinuous permafrost thaw in the boreal peatlands of northern Manitoba, Canada, using a combination of tree-ring analyses to document thaw rates from 1941–1991 and direct measurements of permanent benchmarks established in 1995 and resurveyed in 2002. I used instrumented records of mean annual and seasonal air temperatures, mean winter snow depth, and duration of continuous snow pack from climate stations across northern Manitoba to analyze temporal and spatial trends in these variables and their potential impacts on thaw. Permafrost thaw in central Canadian peatlands has accelerated significantly since 1950, concurrent with a significant, late-20th-century average climate warming of +1.32 °C in this region. There were strong seasonal differences in warming in northern Manitoba, with highest rates of warming during winter (+1.39 °C to +1.66 °C) and spring (+0.56 °C to +0.78 °C) at southern climate stations where permafrost thaw was most rapid. Projecting current warming trends to year 2100, I show that trends for north-central Canada are in good agreement with general circulation models, which suggest a 4–8 °C warming at high latitudes. This magnitude of warming will begin to eliminate most of the present range of sporadic and discontinuous permafrost in central Canada by 2100. 相似文献
17.
Influence of the warm pool and cold tongue El Niños on the following Caribbean rainy season rainfall
Caribbean rainfall and associated regional-scale ocean–atmosphere anomalies are analyzed during and after warm pool (WP) and cold tongue (CT) El Niño (EN) events (i.e. from the usual peak of EN events in boreal winter to next summer from 1950 to 2011). During and after a CT event, a north–south dipolar pattern with positive (negative) rainfall anomalies over the northern (southern) Caribbean during the boreal winter tends to reverse in spring, and then to vanish in summer. On the contrary, during and after a WP event, weak rainfall anomalies during the boreal winter intensify themselves from spring, with anomalous wet conditions over most of the Caribbean basin observed during summer, except over the eastern coast of Nicaragua and Costa Rica. The Caribbean rainfall anomalies associated with WP and CT events are shaped by competition between at least four different, but interrelated, mechanisms; (1) the near-equatorial large-scale subsidence anomaly over the equatorial Atlantic linked to the zonal adjustment of the Walker circulation; (2) the extra-tropical wave-like train combining positive phase of the Pacific/North American mode and negative phase of the North Atlantic Oscillation; (3) the wind-evaporation-sea surface temperature (SST) positive feedback coupling warmer-than-normal SST with weaker-than-normal low level easterlies over the tropical North Atlantic; and (4) the air-sea coupling between the speed of low level easterlies, including the Caribbean low level jet, and the SST anomaly (SSTA) gradient between the Caribbean basin and the eastern equatorial Pacific. It seems that Caribbean rainfall anomalies are shaped mostly by mechanisms (1–3) during CT events from the boreal winter to spring. These mechanisms seem less efficient during WP events when the atmospheric response seems driven mostly by mechanism (4), coupling positive west-east SSTA gradient with weaker-than-normal low level easterlies, and secondary by mechanism (3), from the boreal spring to summer. 相似文献
18.
We examine trends in climate variables and their interrelationships over the Tibetan Plateau using global climate model simulations
to elucidate the mechanisms for the pattern of warming observed over the plateau during the latter half of the twentieth century
and to investigate the warming trend during the twenty-first century under the SRES A1B scenario. Our analysis suggests a
4°C warming over the plateau between 1950 and 2100. The largest warming rates occur during winter and spring. For the 1961–2000
period, the simulated warming is similar to the observed trend over the plateau. Moreover, the largest warming occurs at the
highest elevation sites between 1950 and 2100. We find that increases in (1) downward longwave radiation (DLR) influenced
by increases in surface specific humidity (q), and (2) absorbed solar radiation (ASR) influenced by decreases in snow cover extent are, in part, the reason for a large
warming trend over the plateau, particularly during winter and spring. Furthermore, elevation-based increases in DLR (influenced
by q) and ASR (influenced by snow cover and atmospheric aerosols) appear to affect the elevation dependent warming trend simulated
in the model. 相似文献
19.
An analysis of climate change for global domain and for the European/Mediterranean region between the two periods, 1961–1990 (representing the twentieth century or “present” climate) and 2041–2070 (representing future climate), from the three-member ensemble of the EH5OM climate model under the IPCC A2 scenario was performed. Ensemble averages for winter and summer seasons were considered, but also intra-ensemble variations and the change of interannual variability between the two periods. First, model systematic errors are assessed because they could be closely related to uncertainties in climate change. A strengthening of westerlies (zonalization) over the northern Europe is associated with an erroneous increase in MSLP over the southern Europe. This increase in MSLP is related to a (partial) suppression of summer convective precipitation. Global warming in future climate is relatively uniform in the upper troposphere and it is associated with a 10% wind increase in the subtropical jet cores. However, spatial irregularities in the low-level temperature signal single out some regions as particularly sensitive to climate change. For Europe, the largest near-surface temperature increase in winter is found over its north-eastern part (more than 3°C), and the largest summer warming (over 3.5°C) is over south Europe. For south Europe, the increase in temperature averages is almost an order of magnitude larger than the increase in interannual variability. The magnitude of the warming is larger than the model systematic error, and the spread among the three model realisations is much smaller than the magnitude of climate change. This further supports the significance of estimated future temperature change. However, this is not the case for precipitation, implying therefore larger uncertainties for precipitation than for temperature in future climate projections. 相似文献
20.
Arctic sea ice and Eurasian climate: A review 总被引：12，自引：0，他引：12
GAO Yongqi SUN Jianqi LI Fei HE Shengping Stein SANDVEN YAN Qing ZHANG Zhongshi Katja LOHMANN Noel KEENLYSIDE Tore FUREVIK SUO Lingling 《大气科学进展》2015,32(1):92-114
The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades,including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate.Paleo, observational and modelling studies are covered to summarize several major themes, including: the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era,as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East Asia, spring snowfall over Eurasia, East Asian winter monsoon, and midlatitude extreme weather; and the remote climate response(e.g., atmospheric circulation, air temperature) to changes in Arctic sea ice. We conclude with a brief summary and suggestions for future research. 相似文献