共查询到20条相似文献，搜索用时 31 毫秒
1.
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
2.
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
3.
Phenological data have shown an increase of ca. 10 days in European growing season length in the latter part of the twentieth
century. In general, these changes have been associated with global warming. Here we present a study of thermal growing season
(GS) trends in the Greater Baltic Area, northern Europe. Yearly dates for the start, end and length of the GS were computed
for 49 stations in the studied area, using daily mean temperature measurements. Trends and tendencies of the GS parameters
were analysed within the twentieth century. We also examined GS trends in long records (starting before 1850) from the region.
The results show a general increase of the length of the GS of ca one week since 1951 in the area, where the most considerable
change has occurred in spring (starting ∼6 days earlier). The largest increases were found at stations adjacent to the Baltic
Sea and North Sea, where some Danish stations showed significant increasing trends in the length of the GS of more than 20 days.
The only tendency for a shorter GS was found in Archangelsk, north western Russia. The three longest records displayed large
inter-annual and decadal variability, with tendencies for increased frequencies of longer growing seasons since the 1950s. 相似文献
4.
Most climate change studies on high elevation ecosystems identify changes in biota, while several report abiotic factors. However, very few report expansion of the freeze-free period, or discuss monthly changes of temperature and growing degree days (GDD) during the growing season. This study provides initial data on agriculturally-related aspects of climate change during the growing season (M-J-J-A-S) in the inter-montane desert of the San Luis Valley (SLV), Colorado. Temperature data were gathered from 7 climate stations within the SLV. Based on ordinal days, the last vernal freeze is occurring (p?<?0.05) earlier at 3 stations than in prior years, ranging between 5.52 and 11.86?days during 1981–2007. Significantly-later autumnal freezes are occurring at 5 stations by 5.95–18.10?days, while expansion of the freeze-free period was significantly longer at all stations by 7.20–24.21?days. The freeze-free period averaged about 93?days prior to the 1980s, but now averages about 107?days. Increases (p?<?0.05) in daily mean, maximum, minimum temperature occurred at nearly all stations for each month. Increases in GDD10, GDD4.4 (potato) and GDD5.5 (alfalfa) also occurred at nearly all stations for all months during 1994–2007. Higher temperatures increase the number of GDD, quickening crop growth and maturity, and potentially reducing yield and quality unless varieties are adapted to changes and water is available for the season extension and increased evapotranspiration. 相似文献
5.
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
6.
SONG Yanling Elisabeth SIMELTON CHEN Deliang DONG Wenjie 《Acta Meteorologica Sinica》2005,19(4):501-510
1. IntroductionChinese agriculture has undergone tremendousstructural changes over the last decades. The averagestaple crop productivity has doubled in 25 yr while thepopulation increased by 25 % [China Statistical Year-book (CSY), 2003]. Winter wheat is one of China'smost important staple food crops, with a total farm-ing area of nearly 24 million hectares and a produc-tion exceeding 92 million ton in 2002 (CSY, 2003).Although China has been the world's largest wheatproducer since 1983 (… 相似文献
7.
我国水稻生育期的生态规律及其区划 总被引：9，自引：0，他引：9
在总结水稻生育期生态规律研究成果的基础上,提出了一个水稻发育速度的优化模式。该模式综合考虑了温度和日长对水稻发育速度的影响,经回代检验,预报效果良好。以模式为仿制,用全国主要稻区１６５站１９５１￣１９８０年的光温资料求算早、中、晚稻的生育期,并绘出生育期的日数的距平百分率空间分布图,据图分析我国水稻生育期的时空变化规律并解释其生态原因。 相似文献
8.
利用通化市所属5个气象站1954—2006年日平均温度组成的区域平均时间序列资料、季平均温度资料,分析了短期气温的剧烈变化(本文称之为寒潮和气温骤升)与后期季温度异常的关系,结果发现,冬季短期气温的剧烈变化与后期春、夏季气温距平存在联系,表现在一些特定的寒潮(或气温骤升)爆发日期段总是与后期季的高或低温相对应。在一定的年代背景下,一些日期段还与极端季温度距平存在明显的联系。与后期气温异常联系明显的寒潮爆发、气温骤升日期段存在着周期性,与春季低温对应明显的寒潮爆发日期有5 d的时间间隔;与春季低温对应明显的气温骤升的日期存在着9~11 d的周期,且随着日期的变化,爆发日期之间的间隔有规律的延长和缩短。一些寒潮爆发和气温骤升日期与东北夏季低温冷害存在明显的联系。 相似文献
9.
基于对汛期的理解和认识, 利用Samel等人设计的半客观统计分析方法、Mann-Kendall突变分析、滑动t检验等方法, 通过分析和研究1957—2006年华北台站的日降水资料, 确定了华北汛期起讫的日期。结果表明:华北汛期始于6月30日, 止于8月18日, 持续期为50d。华北汛期的起讫日期、持续天数以及空汛发生的频次, 具有鲜明的地域特征:冀北山地汛期开始最早, 结束较迟, 持续天数较长, 空汛发生频次最少; 黄土高原汛期开始较迟, 其北部汛期结束最迟, 持续期也最长, 发生空汛的频次也比较多; 黄河下游地区汛期开始比较早, 结束最早, 汛期最短, 发生无大汛的频次较大; 河北平原地区, 汛期开始最迟, 结束较迟, 汛期较长, 发生无大汛的频次最多。与华北汛期开始和结束日相对应的东亚大气环流特征是:当西太平洋西部上空500hPa存在正的位势高度距平, 华北上空存在负的位势高度距平, 同时地面为“东高西低”的异常海平面气压场配置时, 异常偏南风到达30°N, 华北汛期开始; 当华北上空500hPa为较小的位势高度正距平, 日本海为位势高度正距平, 而地面上, 我国大陆和西太平洋之间为“西高东低”的异常海平面气压场配置时, 异常偏北风控制我国东部地区, 华北汛期结束。 相似文献
10.
Summary Freeze thaw cycles are examined in Toronto Canada. Using data from 1960 to 1989 for three Toronto area weather stations, trends
in freeze thaw activity, the relationship to mean monthly temperature and projections of freeze thaw activity are examined.
For downtown Toronto the annual frequency of freeze thaw cycles is decreasing significantly, most notably in the shoulder
months of October and April. At the Pearson International Airport and the Toronto Island Airport similar annual trends were
not found, however there was evidence of decreased freeze thaw activity in April and October. Polynomial curve fitting provided
functional relationships between mean monthly temperature and freeze thaw activity. These relationships enabled the assessment
of freeze thaw activity under synthetic warming conditions. The results of this analysis show that the warming of the magnitude
typically projected for the rest of this century will not likely generate a significant change in the freeze thaw activity
although there are indications that the freeze thaw season will contract. 相似文献
11.
Thermal Climate Variations and Potential Modification of the Cropping Pattern in Bangladesh 总被引：1，自引：0，他引：1
R. Mahmood 《Theoretical and Applied Climatology》1998,61(3-4):231-243
Summary Changes in the thermal climate due to inter-annual climatic variability can potentially modify existing cropping pattern
by forcing farmers to rearrange transplanting and harvesting dates. In the present study, a crop climate model, the YIELD,
has been applied to 12 meteorological stations located in major rice growing regions in Bangladesh to estimate the effect
of thermal climate variations on the transplanting and harvesting dates of boro rice and the resultant potential changes in
cropping pattern and spatial shift. The abnormal thermal climate scenarios have been created by synthetically perturbing mean
air temperatures (Tair) up to −5 °C to +5 °C with an interval of 1 °C for each of these stations. Historical meteorological records of air temperature
in Bangladesh have been used to prepare these scenarios. The study finds that under abnormally cool conditions transplanting
dates will be pushed well into February to avoid plant injury and harvesting dates will be moved into the monsoon. The growing
seasons will be longer under cooler than normal thermal conditions. Under abnormally warm conditions harvesting dates will
be established well into March and will cause reduction of yield due to a shorter growing season. These conditions will also
cause spatial shift in crop potential and changes in the cropping pattern. Due to a longer boro rice growing season farmers
will lose a significant amount of cropping land which is usually used for low and deep water rice cultivation. New crops will
need to be introduced during the beginning of a year to overcome the loss of production under abnormally cool conditions.
Wheat and potato can be good options for the farmers for such conditions. New aus rice variety needs to be introduced after
the boro harvesting under warmer than the normal conditions to overcome the loss of yield due to a shorter growing season.
Received September 16, 1996 Revised September 8, 1997 相似文献
12.
近40年温州双季晚稻安全齐穗期变化 总被引：1，自引：0，他引：1
依据温州全市各县(市)气象站自建站以来的逐日日平均气温,分别计算了各站的逐年22℃稳定通过终日,分析了各站该日期的变化特点,确定其变化趋势。运用SPSS(Statistical Product and Service Solution)软件对各站的变化进行显著性检验,判断其变化是由于样本的抽样误差造成还是总体的期望值确实发生了变化。基于温州各站历年的22℃稳定通过终日变化特点,分两个时间段进行讨论,分别计算具有显著性变化站点1990年前后两段时期内的80%保证率22℃稳定通过终日,以此为依据确定当地双季晚稻安全齐穗期的变化,进而计算双季晚稻安全齐穗期的可推迟天数,提出播种期安排建议,从而为更好地利用气候资源,提高当地农田利用效率提供客观依据。 相似文献
13.
中国木本植物物候对气温变化的响应 总被引：1，自引：0，他引：1
本文利用全国21个站的木本植物物候资料和全国599个站的逐日气温资料,分析了1963~1988年中国木本植物物候对气温变化的响应,研究表明:26年来,植物春季物候期与春季气温在全国总体呈负相关,气温越高,物候期越提前;植物秋季物候期与秋季气温在全国呈正相关,但相关性没有春季物候期显著;我国木本植物物候生长季长度有明显的南-北向梯度,早春气温对植物物候生长季的影响比秋末气温对其影响更大。 相似文献
14.
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
15.
浙江省四季划分方法探讨 总被引：3，自引：0，他引：3
利用1971—2011年浙江省63个站逐日气温资料,结合物候观测资料,经过统计计算及对比分析,发现运用候温法来判断换季时间常造成换季偏晚;运用气象学法和气候学法则会造成换季偏早,也很容易造成换季偏晚;各种方法造成的换季异常在各地区呈现出不同的特征。而分析各种方法造成换季时间异常的主要原因,基本都是由于期间几天的气温波动导致换季条件不满足造成的,波动持续时间一般不长,以3～5天为主,波动幅度一般也不大。因此充分考虑各种方法的优缺点,并考虑尽量减少气温波动的影响,总结出一套能够解决这些方法存在的问题,并且相对合理、适用于浙江地区的四季划分方法,得到的结果大大减少了其他方法偏早或由弱冷空气造成的偏晚现象,全省平均四季换季时间分别为3月16日、5月29日、9月30日、12月8日,换季明显偏早或偏晚的频次较其他方法明显减少,在全省各地区均比较符合物候现象。 相似文献
16.
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
17.
Frost-free season lengthening and its potential cause in the Tibetan Plateau from 1960 to 2010 总被引：1，自引：0，他引：1
Dan Zhang Wenhui Xu Jiayun Li Zhe Cai Di An 《Theoretical and Applied Climatology》2014,115(3-4):441-450
Frost-free season was an important index for extreme temperature, which was widely discussed in agriculture and applied meteorology research. The frost-free season changed, which was associated with global warming in the past few decades. In this study, the changes in three indices (the last frost day in spring, the first frost day in autumn, and the frost-free season length) of the frost-free season were investigated at 73 meteorological stations in the Tibetan Plateau from 1960 to 2010. Results showed that the last frost day in spring occurred earlier, significantly in 39 % of the 73 stations. For the regional average, the last frost day in spring occurred earlier, significantly at the rate of 1.9 days/decade during the last 50 years. The first frost day in autumn occurred later, significantly in 31 % of the stations, and the regional average rate was 1.5 days/decade from 1960 to 2010. The changing rate of the first frost day in autumn below 3,000 m was 1.8 times larger than the changing rate above 3,000 m. In addition, the first frost day in autumn above 3,000 m fluctuated dramatically before the early 1990s and then it was later sharply after the early 1990s. The frost-free season length increased significantly at almost all stations in the Tibetan Plateau from 1960 to 2010. For the regional average, the frost-free season lengthened at the rate of 3.1 days/decade. The changing rate of the frost-free season length below 3,000 m was more significant than the changing rate above 3,000 m. Eight indices of large-scale atmospheric circulation were employed to investigate the potential cause of the frost-free season length change in the Tibetan Plateau during the past 50 years. There was a significant relationship between the frost-free season length and the Northern Hemisphere Polar Vortex indices. The weakening cold atmospheric circulation might be an essential factor to the Tibetan Plateau warming since 1960. 相似文献
18.
阿米娜.麦图尔迪 《沙漠与绿洲气象(新疆气象)》2013,7(5):44-50
长白山温带针阔叶混交林作为典型的温带森林生态系统,对气候变化的反应比较敏感,其生长季及积温的变化是准确评价该我国东北林区气候变化的重要依据。本研究采用中国科学院长白山森林生态系统定位站获取的1982-2010年气温目值观测资料,分析了近20a该地区生长季长度及积温的变化,结果标明长白山温带针阔叶混交林29a的平均温度为3．6℃,29a中该地区气温有较弱的上升趋势;长白山温带针阔叶混交林1990-2010年生长季长度的平均值为174d,近20a中生长季长度呈弱增长趋势;长白山温带针阔叶混交林1990～2010年生长季起始日期变化较稳定,生长季终止日期有推后的趋势;长白山温带针阔叶混交林1990-2010年≥5℃的活动积温和有效积温平均值分别为2616．9℃、1744．8℃。近20a中,≥5℃活动积温和有效积温都有着缓慢升高的趋势。 相似文献
19.
以不高于0℃最低气温作为霜冻指标, 利用1961—2006年大连地区3个国家级气象站逐日最低气温资料, 采用现代气候诊断分析方法, 分析了该地区初、终霜冻事件和无霜期变化的特征。结果表明:近46年来, 大连和瓦房店站均表现为初霜冻日推迟、终霜冻日提早、无霜冻期延长的变化趋势, 其中瓦房店站表现得更为显著; 庄河站的初霜冻日和终霜冻日表现出相似的变化, 但各自的变化趋势不显著, 而无霜冻期延长趋势显著; 大连境内极早初霜冻日和极晚终霜冻日发生频数分别为1~3次和1~4次, 大连最多, 瓦房店最少; 大连站的初霜冻日期存在2年和11年的显著周期, 终霜冻日期存在22年的显著周期, 庄河站的初霜冻日期和无霜冻期均存在11年左右显著周期; 异常霜冻事件大连和庄河站20世纪60年代出现的频数最多, 21世纪初最少; 而瓦房店21世纪初异常霜冻事件出现的频数最多, 20世纪80年代最少。 相似文献
20.
M. Bannayan A. Lakzian N. Gorbanzadeh A. Roshani 《Theoretical and Applied Climatology》2011,105(3-4):485-494
Accurate use of precipitation can be considered as one of the best options to decrease the amount of underground water extraction for agriculture in arid and semi-arid areas such as northeast of Iran. For this reason, characteristics of the growing season such as onset, cessation, and length of the growing period should be analyzed. In this paper, we have calculated growing season characteristics of five locations in northeast of Iran using 45?years historical daily weather data and employed four approaches with different calculation methods. As temperature is one of the limiting factors in irrigation-based agriculture, the first approach has been based on this factor. The three remaining approaches were based on joint rainfall and temperature approach, rainfall, evapotranspiration, and temperature approach, and the final approach was based on availability of adequate water in 0.25?m of soil profile. The calculated onset dates using second and third approaches have been based on soil water balance model and relative evapotranspiration rate, and both were evaluated also to find whether the onset is a false start occurrence or not. The results showed that, when temperature was the only limiting factor, Bojnourd station with 197?days showed the longest growing season, however, when precipitation was used along with temperature, longest growing season (124?days) was obtained for Sabzevar station. The third approach which benefits from a water balance model and is similar to rainfed conditions showed the longest growing season with 147?days for Mashhad station. When adequate soil water approach was used, Bojnourd station with 255?days showed the longest growing season. Evaluation of false start of the growing season indicated the lowest probability of false start occurrence for Mashhad compared with other locations. 相似文献