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1.
Fluctuations in the length of the growing season in Minnesota 总被引：3，自引：0，他引：3
Fluctuations in growing season length and in the dates of the last spring freeze and first fall freeze between 1899 and 1982 were studied for five rural Minnesota stations with long, high quality records. A general increase in growing season length was found, but there was substantial variation in the pattern of fluctuations among the stations. The increase in growing season length is not clearly and uniformly related to changes in the dates of first and last freezes. The interannual variability of growing season duration is on the order of the increase in duration so that the change would not be readily apparent to a casual observer. Our results do not correspond well with certain other studies of growing season length nor with fluctuations in hemispheric mean temperature. We conclude that extreme care must be used in extrapolating results of growing season length studies in space and in relating them to mean temperature fluctuations. 相似文献
2.
Global warming exerts a lengthening effect on the growing season, with observational evidences emerging from different regions over the world. However, the difficulty for a global overview of this effect for the last century arises from limited availability of the long-term daily observations. In this study, we find a good linear relationship between the start (end) date of local growing season (LGS) and the monthly mean temperature in April (October) using the global gridded daily temperature dataset for 1960–1999. Using homogenized daily temperature records from nine stations where the time series go back to the beginning of the twentieth century, we find that the rate of change in the start (end) date of the LGS for per degree warming in April (October) mean temperature keeps nearly constant throughout the time. This enables us to study LGS changes during the last century using global gridded monthly mean temperature data. The results show that during the period 1901–2009, averaged over the observation areas, the LGS length has increased by a rate of 0.89 days decade?1, mainly due to an earlier start (?0.58 days decade?1). This is smaller than those estimates for the late half of the twentieth century, because of multidecadal climate variability (MDV). A MDV component of the LGS index series is extracted by using Ensemble Empirical Mode Decomposition method. The MDV exhibits significant positive correlation with the Atlantic Multi–decadal Oscillation (AMO) over most of the Northern Hemisphere lands, but negative in parts of North America and Western Asia for start date of LGS. These are explained by analyzing differences in atmospheric circulation expressed by sea level pressure departures between the warm and cool phases of AMO. It is suggested that MDV in association with AMO accelerates the lengthening of LGS in Northern Hemisphere by 53 % for the period 1980–2009. 相似文献
3.
1971~2013年我国四季开始日期及生长期长度的变化特征分析 总被引：1，自引：0，他引：1
利用中国气象局国家气象信息中心提供的中国584个气象站点1971～2013年的逐日气温数据,采用线性倾向估计和经验模态分解（EMD）等方法,以地理信息系统为数据处理平台,分析我国43年来四季起始日以及生长期的变化特征。结果表明：新疆、云南和四川地区的四季起始日变化呈现明显的南北差异;全国大部分地区春、夏季起始日提前,春季比夏季提前趋势更明显,江苏、安徽、湖北大部和云南北部春季提前显著,提前率为4.1～7.2 d/10 a;夏季提前的区域更广,新疆东部、甘肃西部、华南大部和云南南部夏季提前显著,提前率为2.9～4.6 d/10 a;全国大部分地区秋、冬季起始日推迟,秋季比冬季推迟的范围更大,新疆南部和四川西部秋季推迟明显,推迟率为4.4～8.6 d/10 a;冬季推迟趋势更显著,新疆东南部和青海大部冬季推迟明显,推迟率为4.7～13.8 d/10 a;全国各地区生长期均有延长,最显著的是云川交界处和新疆东南部地区,延长率为20.1 d/10 a。EMD和线性倾向估计的结果基本一致,但EMD得到的春季起始日推迟地区的范围更大,夏、秋、冬季起始日以及生长期的变化趋势更显著。 相似文献
4.
Summary A simple water balance method is used to compute the dates of the onset and termination and length of the growing season from long-term rainfall series in northern Nigeria. For most of the stations, the time series of onset and termination dates and growing season length are homogeneous and random, and can be taken as normally distributed. There is a progressive decrease in the length of the growing season from a mean of about 200 days in the south to less than 155 days in the extreme northern part. While there is no statistically significant trend in the onset dates, there is some evidence for statistically significant decreasing trend in the termination dates and the length of the growing season over the region. The results indicate that recent trends in the length of the growing season are more sensitive.to large interannual fluctuations in the start of the rains than to variations in the cessation dates.With 7 Figures 相似文献
5.
The river ice regime is considered a sensitive indicator of climate change and within this study long term changes (in case of River Daugava starting from 1530, but for other studied rivers starting from first half of twentieth century) river ice regimes in the Baltic region have been studied. The ice cover duration on the rivers (17 rivers) in the Baltic countries and Belarus has decreased during the recent decades. In addition to this, long term observational records of ice break on the rivers of the studied region exhibit a pattern of periodic changes in the intensity of ice regime. Both the ice regime and the seasonal river discharge are shown to be strongly influenced by large-scale atmospheric circulation processes over North Atlantic that manifests through close correlation with North Atlantic Oscillation index. 相似文献
6.
Zhihong Jiang Jie Song Laurent Li Weilin Chen Zhifu Wang Ji Wang 《Climatic change》2012,110(1-2):385-401
Observations from 550 surface stations in China during 1961–2000 are used to evaluate the skill of seven global coupled climate models in simulating extreme temperature and precipitation indices. It is found that the models have certain abilities to simulate both the spatial distributions of extreme climate indices and their trends in the observed period. The models’ abilities are higher overall for extreme temperature indices than for extreme precipitation indices. The well-simulated temperature indices are frost days (Fd), heat wave duration index (HWDI) and annual extreme temperature range (ETR). The well-simulated precipitation indices are the fraction of annual precipitation total due to events exceeding the 95th percentile (R95T) and simple daily intensity index (SDII). In a general manner, the multi-model ensemble has the best skill. For the projections of the extreme temperature indices, trends over the twenty-first century and changes at the end of the twenty-first century go into the same direction. Both frost days and annual extreme temperature range show decreasing trends, while growing season length, heat wave duration and warm nights show increasing trends. The increases are especially manifested in the Tibetan Plateau and in Southwest China. For extreme precipitation indices, the end of the twenty-first century is expected to have more frequent and more intense extreme precipitation. This is particularly visible in the middle and lower reaches of the Yangtze River, in the Southeast coastal region, in the west part of Northwest China, and in the Tibetan Plateau. In the meanwhile, accompanying the decrease in the maximum number of consecutive dry days in Northeast and Northwest, drought situation will reduce in these regions. 相似文献
7.
The aim of this study was to investigate long-term seasonal trends and decadal change patterns of monthly mean water vapor
pressure (WVP) observation series at 16 meteorological stations scattered point-wisely over the Southeastern Anatolian Project (GAP) area in Turkey, where large-scale soil and water development projects have been put into practice since the 1970s. The record
length of WVP observation series of each station varied between 31- and 41-years between 1962 and 2002. The monthly mean WVP
observation series of each station was rearranged on seasonal basis. Sequential Mann–Kendall trend test, Sen’s slope estimator,
and Spearman’s rank–order correlation tests were employed for detection of likely trends, and Kruskall–Wallis test was used
to detect decadal variations in WVP series of each observation station. A possible area of representation for each meteorological
station was determined by using the Thiessen polygons technique in a geographical information systems media. It was found
that 15 seasonal WVP series have a positive trend covering 97% of the GAP area in the summer season; although one WVP series
has a negative trend direction. However, in the spring season, 33% of the area had a positive trend, and a negative trend
did not appear in any stations. WVP records in the winter season showed an increasing trend over 19% of the GAP area, whereas
a decreasing trend prevailed in 9% of the area. The study results led us to conclude that the substantial increase of WVP
observations in summer season could be attributed to both the shift from rain-fed agriculture to irrigated agriculture being
made increasingly spacious year by year and building large water reservoirs in the GAP located in a semi-arid region. The
results also indirectly suggested that the historical trends in the WVP parameters might be related to global climate change
phenomenon. 相似文献
8.
借鉴梅雨指数的定义,选取贵溪、德兴、玉山、衢州、龙泉为5个代表站,建立了江南南部初夏雨季指数。近50a来,江南南部初夏雨季平均开始日和结束日分别是6月10日和7月1日,比江淮梅雨早约8d左右;雨季平均长度为20．5d,雨季内雨日数平均为15．5d;江南南部初夏雨季开始日经历了一个显著的“V型”变化过程,结束日呈“纺锤型”振荡变化;雨季的长度和雨日数没有明显的线性趋势变化,但20世纪80年代期间的雨季长度和雨日数年际变化大,旱涝频率高、强度强;20世纪60年代和21世纪以后雨季偏弱年较多。影响江南南部初夏雨季开始早晚的大气环流关键区主要在乌拉尔山附近,若乌拉尔山附近为阻高型（低槽型）,则雨季开始早（晚）;中高纬系统、太平洋副高和南亚高压也都有影响。影响雨季强度的大气环流关键区分别在东半球的北极区、中低纬度西北太平洋和鄂霍次克海附近上空。 相似文献
9.
Variations and trends of onset, cessation and length of climatic growing season over Xinjiang, NW China 总被引：3，自引：1，他引：2
Feng-qing Jiang Ru-ji Hu Yan-wei Zhang Xue-mei Li Li Tong 《Theoretical and Applied Climatology》2011,106(3-4):449-458
In this study, we assess spatial patterns of variations and trends of onset, cessation, and length of growing season using mean air temperature data recorded at 51 stations in Xinjiang province, NW China over the period 1959?C2008. Rank-based Mann?CKendall trend test and linear regression method are used to detect the significance and the magnitude of growing season change, respectively. Regionally, the average onset of the growing season has shifts 5.3?days earlier while the average ending date has moved 7.1?days later, increasing the length of the growing season by an average of 12.6?days. This study reveals a quite different result from previous studies. While the lengthening of the growing season in Xinjiang in the past 50?years is similar to that of previous studies, we find that the lengthening can be mainly attributed to delay of cessation in autumn rather than advance of onset in spring. The extended growing season will have strong implications in regional agricultural production of Xinjiang. 相似文献
10.
We present an analysis of the inter-annual variability of hydrography—temperature and salinity – and ice conditions at the coastal site of Tvärminne, Gulf of Finland, Baltic Sea during the period 1927–2012. The aim is to analyze the natural variability and trends of the hydrographic characteristics, freezing and breakup dates, ice thickness, and the heat content during the last century. The study also includes the inter-connections between the ice season and the surface temperature and salinity in the open water season. The results showed a significant decrease of the ice season length, by almost 30 days. The maximum annual ice thickness decreased by 8 cm in the last 40 years. The surface water temperature increased by almost 1 °C and there was also an increasing trend in the heat content. The thermal memory of the system was 2–2.5 months. The surface salinity increased by 0.5 psu in the last 85 years. The results are discussed and compared to related studies. 相似文献
11.
A number of studies have reported an extension of the thermal growing season in response to the warming climate during recent decades. However, the magnitude of extension depends heavily on the threshold temperature used: for a given area, a small change in the threshold temperature results in significant differences in the calculated thermal growing season. Here, we specified the threshold temperature for determining the thermal growing season of local vegetation across 326 meteorological stations in temperate China by using vegetation phenology based on satellite imagery. We examined changes in the start, end, and length of the thermal growing season from 1960 to 2009. The threshold temperatures for determining the start and end increased strongly with increasing mean annual temperature. Averaged across temperate China, the start of the thermal growing season advanced by 8.4?days and the end was delayed by 5.7?days, resulting in a 14.1-day extension from 1960 to 2009. The thermal growing season was intensively prolonged (by 0.59?day/year) since the mid-1980s owing to accelerated warming during this period. This extension was similar to that determined by a spatially fixed threshold temperature of 5?°C, but the spatial patterns differed, owing to differences in the threshold temperature and to intra-annual heterogeneity in climate warming. This study highlights the importance of specifying the temperature threshold for local vegetation when assessing the influences of climate change on thermal growing season, and provides a method for determining the threshold temperature from satellite-derived vegetation phenology. 相似文献
12.
13.
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
14.
Summary Reports of changes in the seasonal and annual rainfall in Nigeria suggests that a more detailed analyses of the geographic
extent of these changes and of their impact on agriculture could be of value. Variation in the growing season (April to September)
rainfall from stations across Nigeria was analysed over the 30-yr period, 1960–90. Regression analyses were used to examine
long-term trends. Principal component and cluster analyses were used to group stations with similar trends in standardised
seasonal rainfall. Mean accumulated standardised seasonal rainfall were used to examine short- and medium-term trends for
each of the groups identified. Significant (P ≤ 0.05) decreases in rainy season rainfall were found at 8 stations mostly in the Guinea and arid/semi-arid savannas of northern
Nigeria, whereas no station showed significant increases. Examination of the monthly (April through September) rainfall showed
that only three – Kano, Sokoto and Potiskum in the arid/semi-arid savanna – of the twenty-three stations used in the analysis
had declining rainfall trends for each of the months April to September and subsequently declining seasonal rainfall trends.
However, 12 to 15 stations had consistently declining rainfall trends in atleast some but not all the growing season months.
However, a similar pattern was not the case in terms of increasing rainfall trends, where only one to three stations had consistently
increasing rainfall trends in some but not all of the months from April to September. Stations that showed increasing rainfall
trends were in the southern parts of Nigeria.
Six groups with similar patterns in standardised seasonal rainfall were identified by Principal Component and Cluster analyses.
For most of the groups, the period from 1967 to 1973 was that of consistently below average seasonal rainfall. However, the
timing and extent of the decline varied with location. Common to stations in four of the six groups was a negative trend in
seasonal rainfall for the period considered. The geographic variation in seasonal rainfall trends has tremendous agricultural
significance since there are indications that the reliability of the season is decreasing from the humid forest zone with
positive seasonal trends to the arid/semi-arid savanna with significant negative seasonal trends.
Received June 24, 1998 Revised December 18, 1998 相似文献
15.
基于GIS技术的武威市山洪灾害风险区划初探 总被引：3，自引：0，他引：3
应用1971～2012年武威市各乡镇山洪灾害调查记录,以及武威市内78个区域气象站和4个自动气象站2008～2012年5-9月降水资料,通过对山洪灾害形成的动力条件、孕灾环境、降水背景的分析,确定临界雨量、地形因子、河网密度、汛期雨量、汛期降水日数、汛期中雨日数、汛期大雨日数为影响山洪灾害形成的主要因子,采用主成分分析方法建立武威市山洪灾害区模型。在ArcGIS软件的支持下,对各影响因子进行空间插值、栅格图层计算等操作,将武威市分为山洪灾害高发区、易发区、一般区和低发区4类,初步探索了武威市山洪灾害分布区划。分析表明,武威市山洪灾害由东南向西北递减,南部天祝县呈高发区,易发区主要在南部古浪县,中部平原凉州区为一般区,北部荒漠带民勤极少能形成山洪灾害,为低发区。 相似文献
16.
A study of long term temperature data for fourteen Canadian cities showed that the length of the annual frost free season has increased by average of 7 days since 1940. Change in individual stations ranged from 26 to -17 days resulting in significant shifts in the mean probable dates for the first and the last frost of the season at most stations. No similar trend was shown in three non-urban control stations. Three urban factors: heat island effect, enhanced cloud cover and the rate of population growth - together accounted for 80% of the explained variance in the phenomenon. A multiple regression model was developed to describe the relationship between the change in the season and the urban factors. It is shown that for any appreciable gains to be made in the length of the season at reasonably predictable changes in temperature, such changes in temperature should be accompanied by a modest increase in cloud cover. 相似文献
17.
Response of the starting dates and the lengths of seasons in Mainland China to global warming 总被引：1，自引：0，他引：1
The climatic seasons in China, defined by station-specific daily temperature measures, have changed substantially during the past decades. In the majority of the country, the length of summer has extended and the length of winter has shortened since the 1950s. These changes in the lengths of seasons are linked to the changes in the starting dates of seasons. Namely, the starting date of summer has advanced and the starting date of winter has shifted back. Averaged across the whole country, the starting date of summer has been brought forward by 5.8 days and the season has extended 9 days. On the other hand, the starting date of winter has been delayed by 5.6 days and the season has shortened by 11 days. The changes for spring and fall are relatively smaller. Particularly, spring has started earlier by 5.7 days but shortened by 0.3 day, and fall has started later by 3.2 days but lengthened by 2.3 days. The changes in seasons exhibit apparent regional differences. They are more significant in the north than in the south where the trend of some local changes in seasons is opposite to that of the rest of the country. 相似文献
18.
Jaak Jaagus Agrita Briede Egidijus Rimkus Kalle Remm 《Theoretical and Applied Climatology》2014,118(1-2):57-68
Spatial distribution and trends in mean and absolute maximum and minimum temperatures and in the diurnal temperature range were analysed at 47 stations in the eastern Baltic region (Lithuania, Latvia and Estonia) during 1951–2010. Dependence of the studied variables on geographical factors (latitude, the Baltic Sea, land elevation) is discussed. Statistically significant increasing trends in maximum and minimum temperatures were detected for March, April, July, August and annual values. At the majority of stations, the increase was detected also in February and May in case of maximum temperature and in January and May in case of minimum temperature. Warming was slightly higher in the northern part of the study area, i.e. in Estonia. Trends in the diurnal temperature range differ seasonally. The highest increasing trend revealed in April and, at some stations, also in May, July and August. Negative and mostly insignificant changes have occurred in January, February, March and June. The annual temperature range has not changed. 相似文献
19.
Changes of Accumulated Temperature, Growing Season and Precipitation in the North China Plain from 1961 to 2009 
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下载免费PDF全文 Using the high-quality observed meteorological data, changes of the thermal conditions and precipitation over the North China Plain from 1961 to 2009 were examined. Trends of accumulated temperature and negative temperature, growing season duration, as well as seasonal and annual rainfalls at 48 stations were analyzed. The results show that the accumulated temperature increased significantly by 348.5℃ day due to global warming during 1961-2009 while the absolute accumulated negative temperature decreased apparently by 175.3℃ day. The start of growing season displayed a significant negative trend of -14.3 days during 1961- 2009, but the end of growing season delayed insignificantly by 6.7 days. As a result, the length of growing season increased by 21.0 days. The annual and autumn rainfalls decreased slightly while summer rainfall and summer rainy days decreased significantly. In contrast, spring rainfall increased slightly without significant trends. All the results indicate that the thermal conditions were improved to benefit the crop growth over the North China Plain during 1961-2009, and the decreasing annual and summer rainfalls had no direct negative impact on the crop growth. But the decreasing summer rainfall was likely to influence the water resources in North China, especially the underground water, reservoir water, as well as river runoff, which would have influenced the irrigation of agriculture. 相似文献
20.
Using the high-quality observed meteorological data,changes of the thermal conditions and precipitation over the North China Plain from 1961 to 2009 were examined.Trends of accumulated temperature and negative temperature,growing season duration,as well as seasonal and annual rainfalls at 48 stations were analyzed.The results show that the accumulated temperature increased significantly by 348.5℃ day due to global warming during 1961 2009 while the absolute accumulated negative temperature decreased apparently by 175.3℃ day.The start of growing season displayed a significant negative trend of-14.3 days during 1961-2009,but the end of growing season delayed insignificantly by 6.7 days.As a result,the length of growing sea.son increased by 21.0 days.The annual and autumn rainfalls decreased slightly while summer rainfall and summer rainy days decreased significantly.In contrast,spring rainfall increased slightly without significant trends.All the results indicate that the thermal conditions were improved to benefit the crop growth over the North China Plain during 1961-2009,and the decreasing annual and summer rainfalls had no direct negative impact on the crop growth.But the decreasing summer rainfall was likely to influence the water resources in North China,especially the underground water,reservoir water,as well as river runoff,which would have influenced the irrigation of agriculture. 相似文献