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1.
Temperature data for phenological models   总被引:5,自引:0,他引:5  
In an arid environment, the effect of evaporation on energy balance can affect air temperature recordings and greatly impact on degree-day calculations. This is an important consideration when choosing a site or climate data for phenological models. To our knowledge, there is no literature showing the effect of the underlying surface and its fetch around a weather station on degree-day accumulations. In this paper, we present data to show that this is a serious consideration, and it can lead to dubious models. Microscale measurements of temperature and energy balance are presented to explain why the differences occur. For example, the effect of fetch of irrigated grass and wetting of bare soil around a weather station on diurnal temperature are reported. A 43-day experiment showed that temperature measured on the upwind edge of an irrigated grass area averaged 4% higher than temperatures recorded 200 m inside the grass field. When the single-triangle method was used with a 10°C threshold and starting on May 19, the station on the upwind edge recorded 900 degree-days on June 28, whereas the interior station recorded 900 degree-days on July 1. Clearly, a difference in fetch can lead to big errors for large degree-day accumulations. Immediately after wetting, the temperature over a wet soil surface was similar to that measured over grass. However, the temperature over the soil increased more than that over the grass as the soil surface dried. Therefore, the observed difference between temperatures measured over bare soil and those over grass increases with longer periods between wettings. In most arid locations, measuring temperature over irrigated grass gives a lower mean annual temperature, resulting in lower annual cumulative degree-day values. This was verified by comparing measurements over grass with those over bare soil at several weather stations in a range of climates. To eliminate the effect of rainfall frequency, using temperature data collected only over irrigated grass, is recommended for long-term assessment of climate change effects on degree-day accumulation. In high evaporative conditions, a fetch of at least 100 m of grass is recommended. Our results clearly indicate that weather stations sited over bare soil have consistently higher degree-day accumulations. Therefore, especially in arid environments, phenology models based on temperature collected over bare soil are not transferable to those based on temperature recorded over irrigated grass. At a minimum, all degree-day-based phenology models reported in the literature should clearly describe the weather station site. Received: 25 October 2000 / Revised: 10 July 2001 / Accepted: 10 July 2001  相似文献   

2.
Evaluation of several degree-day estimation methods in California climates   总被引:1,自引:0,他引:1  
 Procedures for estimating degree-day accumulations are frequently employed instead of the more accurate method of calculating degree-days from hourly temperature data because on-site temperature data are commonly restricted to daily minimum and maximum temperature records. Data from seven methods of estimating degree-days at each of nine locations during 2 years in California were compared by month to degree-day values calculated by hourly summation. Methods included three sine-wave approaches, three triangulation approaches and the averaging (i.e., rectangle) method. Results of the double-sine and corrected-sine (i.e., corrected for day length) methods were nearly identical to those of the single-sine method. The double triangulation and corrected triangulation methods produced very similar results to the single triangulation method. The averaging method and sine-wave methods deviated to a greater extent from degree-day accumulations calculated from hourly temperatures from November through February than did the triangulation methods. Degree-day estimations from the late spring and summer months were more similar to one another for all estimation methods than during the cooler months of the year. Since no advantages were noted in the more complicated double and corrected methods, the single triangulation method or the sine-wave method is preferred as they are less complicated procedures. Of the various temperature threshold cut-off methods evaluated, error levels were unaffected when estimating degree-days using the sine-wave method. The employment of a horizontal cut-off with the triangulation method did not significantly increase the amount of error in the estimation of degree-days. However, an increase in error was observed when employing the intermediate cut-off and vertical threshold cut-off techniques with the triangulation method for computing degree-days. Received: 26 May 1998 / Accepted: 28 October 1998  相似文献   

3.
Phenological models based on degree-day accumulation have been developed to support the integrated pest management of many insects. Most of these models are based on linear relationships between temperature and development, and on daily time step simulations using daily minimum and maximum temperatures. This approach represents an approximation that does not take into account the insect physiological response to temperature, and daily temperature fluctuations. The objective of this work has been to develop a phenological model for the European corn borer (ECB) based on the insect physiological response to temperature and running at an hourly time step. Two modeling solutions based on the same generic compartmental system have been compared: the first based on a physiologically based relationship between temperature and development, and using hourly derived temperatures as input (HNL modeling solution); and the second based on a linear relationship between temperature and degree-day accumulation and using daily temperature (DL modeling solution). The two approaches have been compared using ECB moth capture data from the Piemonte region in Northern Italy. The HNL modeling solution showed the best results for all the accuracy indicators. The DL modeling solution showed a tendency to anticipate ECB phenological development too early. This tendency is attributable to the linear relationship between temperature and development, which does not take into account (1) the decline of this relationship at high temperatures, and (2) the daily fluctuation of temperature. As a consequence, degree-days accumulation is accelerated in the DL modeling solution and the phenological development anticipated.  相似文献   

4.
Ectotherms, such as insects, experience non-constant temperatures in nature. Daily mean temperatures can be derived from the daily maximum and minimum temperatures. However, the converse is not true and environments with the same mean temperature can exhibit very different diurnal temperate ranges. Here we apply a degree-day model for development of the grape berry moth (Paralobesia viteana, a significant vineyard pest in the northeastern USA) to investigate how different diurnal temperature range conditions can influence degree-day accumulation and, hence, insect life history. We first consider changes in diurnal temperature range independent of changes in mean temperatures. We then investigate grape berry moth life history under potential climate change conditions, increasing mean temperature via variable patterns of change to diurnal temperature range. We predict that diurnal temperature range change can substantially alter insect life history. Altering diurnal temperature range independent of the mean temperature can affect development rate and voltinism, with the magnitude of the effects dependent on whether changes occur to the daily minimum temperature (Tmin), daily maximum temperature (Tmax), or both. Allowing for an increase in mean temperature produces more marked effects on life history but, again, the patterns and magnitude depend on the nature of the change to diurnal temperature range together with the starting conditions in the local environment. The study highlights the importance of characterizing the influence of diurnal temperature range in addition to mean temperature alone.  相似文献   

5.
有效积温Sine函数拟合模型及其应用   总被引:2,自引:0,他引:2       下载免费PDF全文
阐述了昆虫物候分析的SSPM模型(single sine phonological model)计算方程和过程,该模型采用Sine函数拟合每天温度变化,并利用积分,获取每天有效积温和一定时间内日度累积值.SSPM重要的参数有发育起点温度和上限温度,参与模型计算包括日最高气温和日最低气温2个输入值,在输入值和参数值组合条件下,模型有6个不同计算方程.以棉铃虫(Helicoverpa armigera)为例,介绍了SSPM在昆虫发育历期分析过程,简单表述了模型预测功能.随自动化气象站分布密度增加和Internet技术的发展,模型在区域化害虫管理中有着重要的应用前景.  相似文献   

6.
The activity of the slug Limax maximus was studied in relation to weather. Three hundred-and-fifty-eight hourly observations of activity and weather were made on 21 nights from May until October, 1976. Factors causally important to molluscan activity were included in a step-down correlation-regression analysis of daily and seasonal behavior. The analysis was also performed using weather data from the previous hourly observation. Models using lag-weather did not explain as much variability as did concurrent weather. The regression models explained about 73% to 87% of the observed variation in activity. The most important factors included in the regression models were time of day (circadian rhythm), light intensity, changes in light intensity and surface temperature. Shelter temperature, temperature gradients, length of the night, and time of sunset were also included in some models. Age and hydration were shown to be key factors in other experiments. A model incorporating weather thresholds estimated from field data explained 83.06% of the variability in the activity of L. maximus over the season. The values predicted from the model did not differ significantly from those actually observed in the field (Kolmogorov-Smirnov test, p>0.50).  相似文献   

7.
在建立植物生态生理模型(如光合作用、蒸腾作用数理模型)的过程中,气温、太阳辐射、相对湿度等气象要素的日变化及瞬时资料是必不可少的.本文根据常规台站的日常观测资料,建立了气温、太阳辐射、风速、相对湿度等气象要素日变化的数理模型.并应用实测资料对所建模型进行了验证.实践表明:(1)描述气温日变化的正弦一指数模型通常其模拟结果不甚理想,但通过引用最高温度的时间延迟参数及惯性系数,可增加模拟结果的准确性.(2)根据测量的太阳辐射日总量值以及太阳高度的日变化值等,可准确地模拟太阳辐射的日变化;(3)根据实际水汽压的日均值和气温常规资料可准确模拟相对湿度的日变化.如果区域参数已知或被正确估计。上述方法可得到较为理想的气象要素日变化的模拟结果.  相似文献   

8.
长白山阔叶红松林生长季反射率特征   总被引:14,自引:0,他引:14  
关德新  金明淑  徐浩 《应用生态学报》2002,13(12):1544-1546
根据长白山阔叶红松林气象观测塔上太阳总辐射和反射辐射资料 ,计算了 2 0 0 1年 5月 2 2日~10月 14日森林下垫面的每日整点反射率 .结果表明 ,森林的反射率与太阳高度角有关 ,在太阳高度角很小的日出和日落附近反射率较高 ,太阳高度角大于 30°时反射率变化不大 ,反射率的日变化曲线为U形 .森林的反射率与天空状况有关 ,晴天条件下低太阳高度时的反射率高值明显 ,U形曲线突出 ,昙天时曲线两端高值相对较低 ,U形曲线也相对平坦 ,阴天的日变化曲线则没有明显的规律 ,在某范围内波动 .生长季反射率的变化特点为 6月上旬较高 ,6月下旬稍有下降 ,7~ 9月较稳定 ,10月上旬则逐渐下降 ,反映了冠层叶片物候变化特征 .  相似文献   

9.
1961-2014年中国沿海极端气温事件变化及区域差异分析   总被引:1,自引:0,他引:1  
王晓利  侯西勇 《生态学报》2017,37(21):7098-7113
基于1961-2014年156个地面气象站日尺度的气温数据集,利用趋势分析、小波分析、Mann-Kendall检验、累积距平、Pettitt检验、主成分分析等方法分析了中国沿海地区极端气温事件的时空变化特征。结果表明:中国沿海及各子区域极端气温暖指数呈上升趋势,冷指数和气温日较差呈下降趋势,夜指数的年际倾向率明显大于昼指数的年际倾向率;除相对指数、极高值指数和冷(暖)持续日数的多年均值在各子区域之间相差不大以外,霜冻日数、冰冻日数以及气温日较差的多年均值从北至南依次递减,与之相反,夏季日数、热夜日数、极端气温极低值指数以及生长季长度的多年均值则从北至南依次增加。各子区域极端气温指数年际间的主周期介于2-8 a,均无显著的年代际震荡周期;各子区域极端气温指数的突变主要发生在1980s和1990s期间,冷指数和极低值指数的突变时间稍早于暖指数和极高值指数的突变时间,突变后,极端暖事件和气温的极值事件进入多发阶段,极端冷事件进入相对少发的阶段;主成分分析中第一主成分高载荷的极端气温指数对日均气温和日最高(低)气温均有较好的指示性,这类极端指数两两之间的相关性也较强,低载荷的极端气温指数对日均气温和日最高(低)气温的指示性相对较弱,与其他极端气温指数之间的相关性也均较弱。  相似文献   

10.
温度是苹果花期最为敏感的生态因子,选择两种在黄土高原区具有代表性的不同树龄和树形结构(盛果期小冠开心形和初挂果期自由纺锤形)的富士苹果园,利用小气候梯度自动测定系统在2011—2014年苹果花期进行定位观测,分析花期不同天气类型下(晴天、阴天或多云、雨天)的果园温度梯度及树体温度的变化特征,并基于气象站温度(TM)建立了果园冠下温度(TL)的推算模型.结果表明: 花期果园温度的垂直分布及与园外的差异主要取决于树形结构,而不同天气类型下的差异不显著.平均温度、日最低温度从树冠下到顶部递增,日最高温度、日较差递减.小冠开心形冠层下部晴天日较差最大,多云或阴天冠层中部和顶部日较差较自由纺锤形小.园内外温差的日变化自由纺锤形呈现高 低 高的单波谷形态、而小冠开心形呈单峰形态,园外最低温度高于冠层下部而与冠层中部的温度接近,小冠开心形冠层下的最低温度较园外最低温度更低,特别是多云或阴天更明显,而冠层中部和顶部与园外的温度差异则较自由纺锤形小.线性模型能够较好地推算树冠下部的温度,误差绝对值在1 ℃以内,特别是自由纺锤形果园和雨天条件下效果更好.  相似文献   

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