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1.
Extreme temperatures are key drivers controlling both biotic and abiotic processes, and may be strongly modified by topography and land cover. We modelled mean and extreme temperatures in northern Fennoscandia by combining digital elevation and land cover data with climate observations from northern Finland, Norway and Sweden. Multivariate partitioning technique was utilized to investigate the relative importance of environmental variables for the variation of the three temperature parameters: mean annual absolute minima and maxima, and mean annual temperature. Generalized additive modeling showed good performance, explaining 84–95 % of the temperature variation. The inclusion of remotely sensed variables improved significantly the modelling of thermal extremes in this system. The water cover variables and topography were the most important drivers of minimum temperatures, whereas elevation was the most important factor controlling maximum temperatures. The spatial variability of mean temperatures was clearly driven by geographical location and the effects of topography. Partitioning technique gave novel insights into temperature-environment relationship at the meso-scale and thus proved to be useful tool for the study of the extreme temperatures in the high-latitude setting. 相似文献
2.
利用1951—2009年南京日平均气温、日最高气温以及日最低气温等资料,分析了南京日最高气温和最低气温的长期演变趋势及其与平均温度的关系。结果表明：近60 a来,南京年平均气温、年平均最高气温、年平均最低气温均呈变暖趋势,20世纪90年代增温尤为明显;日最高气温,除夏季表现为降温趋势外,其他季节均为升温趋势;而四季平均气温和平均最低气温均为增温趋势;夏季气温日较差下降趋势明显,导致夏季昼夜温差减小;极端高温、低温的发生日数均呈下降趋势。极端气温与平均气温之间存在明显的相关性,且极端低温对平均气温影响更为明显。 相似文献
3.
1955-2005年中国极端气温的变化 总被引：27，自引：0，他引：27
利用1955-2005年中国234站逐日最高、最低气温资料,通过计算趋势系数等,研究了中国年、季极端气温变化趋势的时空特征。结果表明：空间分布上,我国年和四季的极端低温均表现出稳定的增温趋势;年、春季和夏季极端高温在黄河下游地区出现了较明显的降温趋势,而在华南地区增温趋势较显著;时间演变上,无论年还是四季,极端低温的增温幅度明显大于极端高温的增幅;极端气温在四季均有增温趋势,尤其以冬季的升温最明显;年极端高温和低温的年代际变化基本一致。 相似文献
4.
The experiment described here resulted from simulation analyses of climate-change studies that highlighted the relative importance of changes in the mean and variance of climatic conditions in the prediction of crop development and yield. Growth and physiological responses of four old cultivars of winter wheat, to three temperature and two carbon dioxide (CO2) regimes (350 or 700 ppmv) were studied in controlled environment chambers. Experimental results supported the previous simulation analyses. For plants experiencing a 3 °C increase in day and night temperatures, relative to local long-term mean temperatures (control treatment), anthesis and the end of grain filling were advanced, and grain and dry matter yields were reduced by 27% and 18%, respectively. Increasing the diurnal temperature range, but maintaining the same mean temperature as the control, reduced the maximum leaf area (27%) and grain yield (13%) but did not affect plant development. Differences among the temperature treatments in both phyllochron interval and anthesis date may have resulted from differences between measured air, and unmeasured plant, temperatures, caused by evaporative cooling of the plants. Thermal time (base = 0 °C), calculated from air temperature, from anthesis to the end of grain filling was about 650 °C d for all cultivars and treatments. Doubling ambient CO2 concentration to 700 ppmv reduced maximum leaf area (21%) but did not influence plant development or tiller numbers. 相似文献
5.
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
6.
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
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
7.
The observed long-term trends in extreme temperatures in Hong Kong were studied based on the meteorological data recorded at the Hong Kong Observatory Headquarters from 1885-2008. Results show that, over the past 124 years, the extreme daily minimum and maximum temperatures, as well as the length of the warm spell in Hong Kong, exhibit statistically significant long-term rising trends, while the length of the cold spell shows a statistically significant decreasing trend. The time-dependent return period analysis also indicated that the return period for daily minimum temperature at 4°C or lower lengthened considerably from 6 years in 1900 to over 150 years in 2000, while the return periods for daily maximum temperature reaching 35°C or above shortened drastically from 32 years in 1900 to 4.5 years in 2000. Past trends in extreme temperatures from selected weather stations in southern China from 1951-2004 were also assessed. Over 70% of the stations studied yielded a statistically significant rising trend in extreme daily minimum temperature, while the trend for extreme maximum temperatures was found to vary, with no significant trend established for the majority of stations. 相似文献
8.
近半个世纪辽宁省气温、降水极值特征分析 总被引：10，自引：4，他引：6
利用辽宁省53个气象站近半个世纪以来的气温、降水极值资料,分析了辽宁省气温、降水极值的时空变化特征。结果表明:辽宁省累年极端最高、最低气温具有区域性,辽西极端最高气温最高,辽东极端最低气温最低,累年极端日降水的局域性较强;最高气温极值多发生在6~8月,但有很多地区都出现在6月,最低气温极值最易发生在1月,降水极值在7月或8月出现最多;最高气温极值和日降水极值的趋势性较弱,而最低气温极值的升温趋势十分显著,且远大于平均气温的增幅;最高(低)气温极值异常主要存在5(4)个空间型,各空间型均存在一定的时间变化特征;最高、最低气温和日降水极值具有不完全一致的长、短周期,但分别以9年、18年、11年左右的周期振动最强;近46年来三个极值要素均出现过增温或减少的突变。 相似文献
9.
利用1961~2015年CN05.1高分辨率的逐日最高、最低气温格点资料,计算6个极端气温指数（极端最高气温、极端最低气温、结冰日数、霜冻日数、暖日日数、冷夜日数）,通过趋势分析和Mann-Kendall突变检验,考察青藏高原极端气温事件的时空变化规律。结果表明:青藏高原极端最高气温、极端最低气温的总体分布呈现西冷东暖的特征,与地形西高东低一致;该地区极端最高气温、极端最低气温及暖日日数均呈上升趋势,倾向率分别为0.25℃/10a、0.42℃/10a、2.14d/10a,极端最低气温的线性增温趋势较极端最高气温更为明显;而结冰日数、霜冻日数及冷夜日数均呈下降趋势,倾向率分别为?3.09d/10a、?4.75d/10a、?2.31d/10a;从空间分布看,青海地区极端最高气温的增温趋势最为显著,柴达木盆地是明显的升温中心;在时间变化上,极端最高气温、结冰日数、暖日日数均在1997年发生了突变。 相似文献
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11.
近年华北地区大面积推行保护性耕作措施和作物秸秆粉碎还田,冬小麦与夏玉米一年两熟连续轮作种植,为沟金针虫创造了有利的取食和栖息环境。地处华北北部的中国气象局固城农业气象野外科学试验基地2018—2019年秋季、冬季、春季气温出现了冷暖交替,尤其最低气温显著偏高,诱发麦田沟金针虫爆发性发生为害。据春季麦田挖土调查,虫口密度最高达144头·m-2,虫口重量最重达18.764 g·m-2。58个调查点达防治指标5头·m-2占98.27%。拔节-收获期调查虫口密度孕穗期最高,拔节期次之,收获期最低。冬小麦与夏玉米禾本科作物连作种植田间虫口密度达35.3~40.4头·m-2,显著高于前茬大豆、玉米、冬小麦休闲地,且花生地、春玉米地比大豆地虫口密度高5倍多,虫口重量高10倍以上。成熟期虫害麦田测产,籽粒减产36.8%;虫口密度增加10头·m-2,籽粒减产率增加4.824%;虫口重量增加1 g·m-2,籽粒减产率增加3.871%;植株虫害率增加10%,籽粒减产率增加11.587%。 相似文献
12.
Increased yield potential of wheat-maize cropping system in the North China Plain by climate change adaptation 总被引：11，自引：0，他引：11
In the North China Plain, the grain yield of irrigated wheat-maize cropping system has been steadily increasing in the past decades under a significant warming climate. This paper combined regional and field data with modeling to analyze the changes in the climate in the last 40 years, and to investigate the influence of changes in crop varieties and management options to crop yield. In particular, we examined the impact of a planned adaptation strategy to climate change -“Double-Delay” technology, i.e., delay both the sowing time of wheat and the harvesting time of maize, on both wheat and maize yield. The results show that improved crop varieties and management options not only compensated some negative impact of reduced crop growth period on crop yield due to the increase in temperature, they have contributed significantly to crop yield increase. The increase in temperature before over-wintering stage enabled late sowing of winter wheat and late harvesting of maize, leading to overall 4–6% increase in total grain yield of the wheat-maize system. Increased use of farming machines and minimum tillage technology also shortened the time for field preparation from harvest time of summer maize to sowing time of winter wheat, which facilitated the later harvest of summer maize. 相似文献
13.
江苏省近45a极端气候的变化特征 总被引：13，自引：8，他引：5
利用江苏省35个测站1960—2004年45 a的逐日最高温度、最低温度、日降水量资料集,分析了近45 a江苏省极端高温、极端低温以及极端降水的基本变化特征。结果表明:(1)多年平均年极端高温的空间分布表现为西高东低,而极端低温则表现为自北向南的显著增加,极端降水的发生频次自南向北逐渐减少;(2)极端高温在江苏中部以及南部大部分地区有上升趋势,而西北地区则有弱的下降趋势;全省极端低温表现为显著的升高趋势;极端降水频次在南部地区有增加的趋势,北部减少趋势,中部则无变化趋势。(3)江苏极端高温、低温和极端降水的年际和年代际变化具有区域性差异,其中极端降水频次变化的区域性差异最为明显。 相似文献
14.
The purpose of this paper is to analyze the trends and variability in extreme temperature indices and its impact on rice–wheat productivity over two districts of Bihar, India, which is part of the middle Indo-Gangetic Basin. Mann–Kendall non-parametric test was employed for detection of trend and Sen slope was determined to quantify the magnitude of such trends. We have analyzed 10 extreme temperature indices for monthly and seasonally. The influence of extreme temperature indices on rice–wheat productivity was determined using correlation analysis. As far as Patna is concerned, if the number of cool days during September ≥10, the rice productivity will increase due to the availability of sufficient duration to fill up the grain. However, higher warm days during all the months except June will affect the productivity. A significant negative correlation was noticed between maximum value of minimum temperature during September and rice productivity. Highly significant positive correlation was noticed between number of cool days during September with rice productivity while it was highly significant negative correlation in the case of number of warm days during the same month. As far as Samastipur is concerned, a negative correlation was noticed between wheat productivity and maximum value of maximum temperature (TXx) during February, but not statistically significant. The higher temperature may affect the kernel weight and thereby yield. It is seen that a critical value of TXx ≥29.2 °C will be harmful to wheat crop during February. A significant positive correlation of number of cool nights with wheat productivity also supports the above relationship. The critical values of extreme temperature indices during rice and wheat growing months provide an indicator to assess the vulnerability of rice–wheat productivity to temperature for Patna and Samastipur districts and there is a need to prepare an adaptive strategy and also develop thermo-insensitive rice–wheat high yielding varieties suitable for this region to sustain rice–wheat productivity under projected climate change situation. 相似文献
15.
With temperatures increasing as a result of global warming,extreme high temperatures are becoming more intense and more frequent on larger scale during summer in China.In recent years,a variety of researches have examined the high temperature distribution in China.However,it hardly considers the variation of temperature data and systems when defining the threshold of extreme high temperature.In order to discern the spatio-temporal distribution of extreme heat in China,we examined the daily maximum temperature data of 83 observation stations in China from 1950 to 2008.The objective of this study was to understand the distribution characteristics of extreme high temperature events defined by Detrended Fluctuation Analysis(DFA).The statistical methods of Permutation Entropy(PE)were also used in this study to analyze the temporal distribution.The results showed that the frequency of extreme high temperature events in China presented 3 periods of 7,10—13 and 16—20 years,respectively.The abrupt changes generally happened in the 1960s,the end of 1970s and early 1980s.It was also found that the maximum frequency occurred in the early 1950s,and the frequency decreased sharply until the late 1980s when an evidently increasing trend emerged.Furthermore,the annual averaged frequency of extreme high temperature events reveals a decreasing-increasing-decreasing trend from southwest to northeast China,but an increasing-decreasing trend from southeast to northwest China.And the frequency was higher in southern region than that in northern region.Besides,the maximum and minimum of frequencies were relatively concentrated spatially.Our results also shed light on the reasons for the periods and abrupt changes of the frequency of extreme high temperature events in China. 相似文献
16.
Summer Extreme Temperatures over East China during 1984-2004 Simulated by LASG/IAP Regional Climate Model CREM 
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下载免费PDF全文 The authors examine extreme summer temperatures over East China during 1984-2004 using a regional climate model named CREM(the Climate version of Regional Eta-coordinate Model),which was developed by LASG/IAP.The results show that the main features of the extreme summer temperatures over East China are reproduced well by CREM,and the skill for the minimum temperature is higher than that for the maximum temperature,especially along the Yangtze-Huai River Valley(YHV).The simulated extreme temperatures are lower than those of observation,especially for the maximum temperature.The bias of extreme temperatures is consistent with the cold bias of the climatological mean summer surface air temperature.The skill of the model in simulating the interannual variability of extreme temperatures increases from north to south.The simulated interannual variation of the minimum temperature is more reasonable than the maximum temperature.The underestimation of net solar radiation at the surface leads to a cold bias of the climatological mean temperature.Furthermore,the model underestimates the light and moderate rain,while overestimates heavy rain.It causes the simulated minimum temperature more reasonable than the maximum temperature. 相似文献
17.
Record-breaking extreme temperatures have been measured in the last two decades all over Turkey, with recent studies detecting positive trends in extreme temperature time series. In this study, nonstationary extreme value analysis was performed on extreme temperature time series obtained from fifty stations scattered over the seven geographical regions of Turkey. Basic characterization of the data set was defined through outlier detection, homogeneity, trend detection, and stationarity tests. Trend-including non-stationary extreme temperature time series were analyzed with non-stationary Generalized Extreme Value distribution. Three main physical drivers were considered as the leading causes that trigger the observed trends in extreme temperatures over Turkey: time, teleconnection patterns of the Arctic Oscillations, and those of the North Atlantic Oscillations. The results showed that most of the absolute annual minimum and maximum temperature time series are inhomogeneous while the possible breakpoints date back to the1970s and 1990s, respectively. More than half of the absolute annual maximum time series (26/50 and many of the absolute annual minimum time series (21/50) showed a positive trend. No negative trend was detected in the extreme temperature time series. Based on the frequency analysis of the 21 annual maximum time series, the non-stationary estimations of 50-year return levels were detected to be higher than in the stationary model (between 0.44 °C and 3.73 °C). The return levels in 15 of the 20 minimum temperature time series increased from 0.11 °C up to 12.28 °C. Elevation increases the nonstationarity impact on absolute minimum temperatures and decreases it on absolute maximums. The findings in this study indicate that the consideration of non-stationarity in extreme temperature time series is a necessity during return level estimations over the study area. 相似文献
18.
Allison M. Thomson Robert A. Brown Steven J. Ghan R. Cesar Izaurralde Norman J. Rosenberg L. Ruby Leung 《Climatic change》2002,54(1-2):141-164
Crop growth models, used in climate change impact assessments to project production on a local scale, can obtain the daily weather information to drive them from models of the Earth's climate. General Circulation Models (GCMs), often used for this purpose, provide weather information for the entire globe but often cannot depict details of regional climates especially where complex topography plays an important role in weather patterns. The U.S. Pacific Northwest is an important wheat growing region where climate patterns are difficult to resolve with a coarse scale GCM. Here, we use the PNNL Regional Climate Model (RCM) which uses a sub-grid parameterization to resolve the complex topography and simulate meteorology to drive the Erosion Productivity Impact Calculator (EPIC) crop model. The climate scenarios were extracted from the PNNL-RCM baseline and 2 × CO2 simulationsfor each of sixteen 90 km2 grid cells of the RCM, with differentiation byelevation and without correction for climate biases. The dominant agricultural soil type and farm management practices were established for each grid cell. Using these climate and management data in EPIC, we simulated winter wheat production in eastern Washington for current climate conditions (baseline) and a 2 × CO2 `greenhouse' scenario of climate change.Dryland wheat yields for the baseline climate averaged 4.52 Mg ha–1 across the study region. Yields were zero at high elevations where temperatures were too low to allow the crops to mature. The highest yields (7.32 Mgha–1) occurred at intermediate elevations with sufficientprecipitation and mild temperatures. Mean yield of dryland winter wheat increased to 5.45 Mg ha–1 for the 2 × CO2 climate, which wasmarkedly warmer and wetter. Simulated yields of irrigated wheat were generally higher than dryland yields and followed the same pattern but were, of course, less sensitive to increases in precipitation. Increases in dryland and irrigated wheat yields were due, principally, to decreases in the frequency of temperature and water stress. This study shows that the elevation of a farm is a more important determinant of yield than farm location in eastern Washington and that climate changes would affect wheat yields at all farms in the study. 相似文献
19.
重庆市气温变化趋势及其可能原因分析 总被引：3，自引：1，他引：2
通过对重庆市1924～2007年的平均气温、平均最高气温、平均最低气温、极端最高气温、极端最低气温随时间变化特征进行分析发现:近84年来重庆市平均气温微弱变冷,与全国平均温度相比线性变化趋势存在一定差异;平均最高和平均最低气温、极端最高和极端最低气温的非对称性变化显著,最高气温的下降对平均气温的影响很大,平均最低气温除春季外增暖都非常显著,最低温度的增高对气温日较差减小的影响更明显.夏季副热带高压位置偏南,使得我国西南地区东部夏季降水天气增多、云量增加、日照时数减少,加之轻雾日数增多,可能是重庆市夏季最高温度持续下降的主要原因.冬季最低气温的显著升高主要是由于降水天气减少、云量增加和城市热岛效应所致. 相似文献
20.
Consensus on global warming is the result of multiple and varying lines of evidence, and one key ramification is the increase in frequency of extreme climate events including record high temperatures. Here we develop a metric—called “record equivalent draws” (RED)—based on record high (low) temperature observations, and show that changes in RED approximate changes in the likelihood of extreme high (low) temperatures. Since we also show that this metric is independent of the specifics of the underlying temperature distributions, RED estimates can be aggregated across different climates to provide a genuinely global assessment of climate change. Using data on monthly average temperatures across the global landmass we find that the frequency of extreme high temperatures increased 10-fold between the first three decades of the last century (1900–1929) and the most recent decade (1999–2008). A more disaggregated analysis shows that the increase in frequency of extreme high temperatures is greater in the tropics than in higher latitudes, a pattern that is not indicated by changes in mean temperature. Our RED estimates also suggest concurrent increases in the frequency of both extreme high and extreme low temperatures during 2002–2008, a period when we observe a plateauing of global mean temperature. Using daily extreme temperature observations, we find that the frequency of extreme high temperatures is greater in the daily minimum temperature time-series compared to the daily maximum temperature time-series. There is no such observable difference in the frequency of extreme low temperatures between the daily minimum and daily maximum. 相似文献