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1引言日照是指太阳在一地实际照射的时数。日照时数也称实照时数[1];其定义为,在一给定时间,太阳直接辐照度达到或超过120瓦·米-2(W·m-2)的那段时间总和,以小时(h)为单位,取一位小数。日照时数表示一个地区接受太阳光照射的时间长短,直观反映太阳辐射,是农业生产重要的环境因素,对人民的日常生活影响重大。 相似文献
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准确记录日照时数应注意的几个问题 总被引：2，自引：0，他引：2
目前 ,各基层气象台站所使用的日照计均为暗筒式日照计。这种仪器可利用太阳光在涂有感光药剂的日照纸上留下感光迹线来测量日照时数 ,笔者在统计日照时数时 ,有时发现当天的太阳光照时间与其实有日照时数不符的异常情况。本文在假定日照测量仪安装无误的前提下 ,仅从气象观测员在观测日照时数时所依据的有关操作规范出发 ,指出了准确观测日照时数应注意的若干问题。1 日照时数观测中应注意的若干问题1 .1 日照迹线起止时刻的辨认日照迹线的开始和终止时刻的准确辨认是保证日照时数统计无误的关键。而在一些特殊天气条件下对其迹线的开始… 相似文献
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利用线性分析方法,根据河南31个站1954~2005年的日照资料分析了河南省及濮阳市的日照变化特征。结果表明,河南省年日照时数呈减少趋势,平均减少每10年74.2 h,东部平原地区年日照时数的递减幅度明显大于西部山区年日照时数的递减幅度。濮阳市年日照时数的递减幅度为每10年135 h,冬季与夏季日照的递减幅度大于春季和秋季日照递减幅度,日照时数减少时段主要发生在日出后和日落前太阳高度角较低的两段时间内。造成日照减少的气候原因主要是空气污染逐年加重,加之风速逐年减小,利于大气气溶胶在低空积聚,空气湿度增大,轻雾日数增多,造成大气透明度降低。非气候因素的影响主要是观测场周围障碍物高度角逐年增高,遮挡了部分阳光,使记录到的日照时数减少,气候因素对日照的影响大于非气候因素的影响。 相似文献
4.
台站使用的暗筒式日照计,是利用通过仪器上的小孔射入筒内的太阳光在日照纸上留下的感光迹线计算日照时数的。上午和下午的日照迹线应是对称的两条曲线。可照时数是太阳中心从出现在一地的东方地平线到进入西方地平线,其直线光线在无地物、云、雾等任何遮蔽的条件下,照射到地面所经历的时间。因此,日照时数应＜可照时数。然而,在审核或检查台站的记录时,却发现有日照时数＞可照时数（或半天日照时数＞半天可照时数）的现象。这往往是观测员在感光迹线的开始（或终止）处向前（或向后）多划铅笔线所造成。由于早上和傍晚太阳光线较弱,… 相似文献
5.
濮阳日照变化趋势及成因分析 总被引：5，自引：1，他引：4
利用线性分析方法,分析了濮阳市1955—2005年日照变,艺特征,分析结果表明：濮阳市年日照时数的趋减幅度为135h／10a,冬季与夏季日照的递减幅度大于春季和秋季日照递减幅度,日照时数减少时段主要发生在日出后和日落前太阳高度角较低的两段时间内。造成日 照减少的气候原因主要是空气污染逐年加重,加之风速逐年减小,利于大气气溶胶在低空积聚,空气湿度增大,使轻雾目数增多,造成大气透明度降低。非气候因素的影响主要是观测场周围障碍物高度角逐年增高,遮挡了部分阳光,使记录到的目照时数减少。气候因素对日照的影响大于非气候因素的影响。 相似文献
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近50年云贵高原楚雄市日照时数变化特征及其成因分析 总被引：4，自引：0，他引：4
利用近50年云南省楚雄市气象观测站日照资料,采用线性倾向估计法分析了楚雄市日照随时间的变化特征,并使用统计分析软件对日照变化的影响因素进行了相关性分析。结果表明,近50年楚雄市日照时数年代际变化呈减少趋势;日照时数月变化为11月一次年4月多于5-10月,即干季多于雨季;日照时数最多的月份是3月,最少的是7月;对近10年日照时数日变化而言,14:00(北京时)日照最为充足。通过相关分析得到日照时数的变化与自然因子中的云量、雾日和年降水量呈负相关关系;与人为因子也呈负相关关系。 相似文献
8.
观测场四周障碍物对日照记录的影响分析 总被引：3，自引：0，他引：3
分别计算赤道、赤道与北回归线之间、北回归线、北回归线以北测站的太阳高度角和日出、日落方位,分析其变化规律,通过分析,给出我国纬度范围内日照记录受障碍物影响的范围。以宜昌站(30°42′N,111°18′E)为例,给出了测站障碍物对日照记录影响分析流程,有利于指导气象台站对障碍物影响程度的定量计算,还可为日照、太阳辐射测量仪器的安装位置的确定,提供有益的借鉴。以广州站(23°10′N,113°20′E)、宜昌站(30°42′N,111°18′E)和北京站(39°48′N,116°28′E)为例,给定障碍物,统计分析出可能影响日照记录的日数和日期、影响日内可能受到影响的时间和日照时数,以及全年最大可能影响日照时数和日照百分率。结果表明:在我国,各地日出所处方位为37°～143°,日落所处方位为217°～323°,在323°～37°方位(正北偏东或偏西)的任何障碍物对日照记录都不会产生影响;南面的障碍物及其偏东或偏西一定范围内,由于太阳高度角较高,不容易对日照产生影响;相同宽度角和高度角的障碍物,单日影响日照时数的最大值随着纬度的增高而增大,最大影响方位的障碍物对年日照百分率影响程度基本相同。 相似文献
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锡林浩特市太阳辐射变化及相关气象要素分析 总被引：1，自引：0，他引：1
利用1990—2010年锡林浩特气象站太阳总辐射、日照时数、日照百分率、降水量、气温以及总云量的观测资料,运用5a滑动平均及最小二乘原理等方法,分析了锡林浩特市1990—2010年来的总辐射变化规律,并分析了气温、降水、日照、云量等的变化以及与太阳总辐射的相关关系。研究结果表明,锡林浩特市太阳总辐射呈现波动增加的趋势,但四季太阳辐射量在近21a的年际波动略有不同。相关要素分析表明,太阳总辐射与日照时数和夏季、秋季气温有很显著的正相关关系,与降水量和春季、夏季的总云量呈负相关关系。 相似文献
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利用1961-2010年杭州站太阳总辐射、日照、降水、云量、水汽压和视程障碍日数资料,采用气候倾向率、突变检测和相关分析等方法,研究了近50 a太阳总辐射和日照时数的变化特征及其成因.结果表明,近50 a杭州年太阳总辐射和日照时数均呈减少趋势,以日照时数下降更明显,其突变年份分别发生在1975和1971年;年太阳总辐射下降主要出现在1961-1992年,1993-2010年呈波动变化,1993年以后未出现明显“变亮期”,而年日照时数在上述两个时段都表现为显著下降趋势,至21世纪00年代降到最低.夏、秋、冬3季太阳总辐射和日照时数趋势变化与年变化基本一致,春季两者在1961-1992年均呈下降趋势,1993年后存在较明显的“变亮期”.降水量、低云量和轻雾日的增加是造成杭州年及夏、秋、冬3季太阳总辐射和日照时数减少的主要原因,春季太阳总辐射的增加则主要与降水量、雨日、总云量和低云量减少关系密切,此外,霾日数变化对日照时数的影响也非常重要. 相似文献
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The Combined Effect of Initial Error and Model Error on ENSO Prediction Uncertainty Generated by the Zebiak-Cane Model 
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下载免费PDF全文 Initial errors and model errors are the source of prediction errors. In this study, the authors compute the conditional nonlinear optimal perturbation （CNOP）-type initial errors and nonlinear forcing singular vector （NFSV）- type tendency errors of the Zebiak-Cane model with respect to El Nifio events and analyze their combined effect on the prediction errors for E1 Nino events. The CNOP- type initial error （NFSV-type tendency error） represents the initial errors （model errors） that have the largest effect on prediction uncertainties for E1 Nifio events under the perfect model （perfect initial conditions） scenario. How- ever, when the CNOP-type initial errors and the NFSV- type tendency errors are simultaneously considered in the model, the prediction errors caused by them are not am- plified as the authors expected. Specifically, the predic- tion errors caused by the combined mode of CNOP-type initial errors and NFSV-type tendency errors are a little larger than those caused by the NFSV-type tendency er- rors. This fact emphasizes a need to investigate the opti- mal combined mode of initial errors and tendency errors that cause the largest prediction error for E1 Nifio events. 相似文献
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Time-Dependent Nonlinear Forcing Singular Vector-Type Tendency Error of the Zebiak-Cane Model 下载免费PDF全文
下载免费PDF全文 Based on the Zebiak-Cane model, the timedependent nonlinear forcing singular vector （NFSV）-type tendency errors with components of 4 and 12 （denoted by NFSV-4 and NFSV-12） are calculated for predetermined El Nifio events and compared with the constant NFSV （denoted by NFSV-1） from their patterns and resultant prediction errors. Specifically, NFSV-1 has a zonal dipolar sea surface temperature anomaly （SSTA） pattern with negative anomalies in the equatorial eastern Pacific and positive anomalies in the equatorial central-western Pa- cific. Although the first few components in NFSV-4 and NFSV-12 present patterns similar to NFSV-1, they tend to extend their dipoles farther westward; meanwhile, the positive anomalies gradually cover much smaller regions with the lag times. In addition, the authors calculate the predic- tion errors caused by the three kinds of NFSVs, and the results indicate that the prediction error induced by NFSV-12 is the largest, followed by the NFSV-4. However, when compared with the prediction errors caused by random tendency errors, the NFSVs generate significantly larger prediction errors. It is therefore shown that the spatial structure of tendency errors is important for producing large prediction errors. Furthermore, in exploring the tendency errors that cause the largest prediction error for E1 Nifio events, the timedependent NFSV should be evaluated. 相似文献
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我国散射辐射的气候计算方法及其分布特征 总被引：1，自引：0，他引：1
使用全国６４个日射站的散射辐射资料，首先计算与建立了各地１月、４月、７月和１０月的月散射辐射值与总云量、日照百分率之间的相关系数与经验关系式，并对经验关系式进行了方差检验。该经验关系式为：Ｄ＝Ｑ０（ｓ１＋０．０１）（ａ＋ｂＮ）。应用该经验关系式和２００多个地面气象站的资料，计算了各地的１月、４月、７月和１０月的散射辐射值。最后对我国四季散射辐射的分布及其年变化作简要的分析。 相似文献
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本文用2019年1～3月四川全省156个国家级地面观测站日照时数平行观测资料，对比评估了自动与人工观测日照时数的小时、日值一致性及分级一致性，分析空间分布规律和不同日照时长对一致性的影响，结果表明:大多数台站人工日照时数略> 自动观测，人工观测值较自动值偏小的台站、二者间均方根误差较大、小时相关系数较低的台站均多出现在盆地地区；攀枝花、甘孜、阿坝、凉山(以下简称“攀枝花、三州”)等日照充足的地区相较于多阴雨的盆地，人工与自动日照时数更接近；攀枝花、三州区域人工观测在日照时长较长的情况下更准确，盆地区域人工观测在日照时长较短的情况下更准确；日自动日照时数> 8h时，人工观测值较自动值易出现偏小，全省人工观测值与自动观测值之间的误差更小，相关性更高；日自动日照时数< 8h时，人工观测值较自动值易出现偏大，在2～8h时，全省人工与自动观测值之间的误差更大，相关性也更差。 相似文献
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The Soil Moisture and Net Primary Production Affected by CO_2 and Climate Change Using a Coupled Model 下载免费PDF全文
下载免费PDF全文 In this paper, a coupled model was used to estimate the responses of soil moisture and net primary production of vegetation （NPP） to increasing atmospheric CO2 concentration and climate change. The analysis uses three experiments simulated by the second-generation Earth System Model （CanESM2） of the Canadian Centre for Climate Modelling and Analysis （CCCma）, which are part of the phase 5 of the Coupled Model Intercomparison Project （CMIP5）. The authors focus on the magnitude and evolution of responses in soil moisture and NPP using simulations modeled by CanESM, in which the individual effects of increasing CO2 concentration and climate change and their combined effect are separately accounted for. When considering only the single effect of climate change, the soil moisture and NPP have a linear trend of 0.03 kg m^-2 yr^-1 and-0.14 gC m^- 2 yr^-2, respec- tively. However, such a reduction in the global NPP results from the decrease of NPP at lower latitudes and in the Southern Hemisphere, although increased NPP has been shown in high northern latitudes. The largest negative trend is located in the Amazon basin at -1.79 gC m^-2 yr^-2. For the individual effect of increasing CO2 concentration, both soil moisture and NPP show increases, with an elevated linear trend of 0.02 kg m^-2 yr^-1 and 0.84 gC m^-2 yr^-2, respectively. Most regions show an increasing NPP, except Alaska. For the combined effect of increasing atmospheric CO2 and climate change, the increased soil moisture and NPP exhibit a linear trend of 0.04 kg m^2 yr^-1 and 0.83 gC m^2 yr^-2 at a global scale. In the Amazon basin, the higher reduction in soil moisture is illustrated by the model, with a linear trend of-0.39 kg m^-2 yr^-1, for the combined effect. Such a change in soil moisture is caused by a weakened Walker circulation simulated by this coupled model, compared with the single effect of increasing CO2 concentration （experiment M2）, and a consequence of the reduction in NPP is also shown in this area, with a linear trend of- 相似文献
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Results of a CLM4 Land Surface Simulation over China Using a Multisource Integrated Land Cover Dataset 下载免费PDF全文
下载免费PDF全文 In this study, the high-accuracy multisource integrated Chinese land cover （MICLCover） dataset was used in version 4 of the Community Land Model （CLM4） to assess how the new land cover information affected land surface simulation over China. Compared to the default land cover dataset in CLM4, the MICL data indicated lower values for bare soil （14.6% reduction）, nee- dleleaf tree （3.6%）, and broadleaf tree （1.9%）; higher values for shrub cover （1.8% increase）, grassland （9.9%）, cropland （5.0%）, glaciers （0.5%）, lakes （1.6%）, and wetland （1.1%）; and unchanged for urban areas. Two comparative CLM4 simulations were conducted for the 33-yr period from 1972 to 2004, one using the MICL dataset and the other using the default dataset. The results revealed that the MICL data produced a 0.3% lower mean annual surface albedo over China than the original data. The largest contributor to the reduced value was semiarid regions （2.1% reduction）. The MICL-data albedo value agreed more closely with observations （MODIS broad- band black-sky albedo products） over arid and semiarid regions than for the original data to some extent. The simulated average sensible heat flux over China increased by only 0.1 W m 2 owing to the reduced values in arid and semiarid regions, as opposed to increases in humid and semihumid regions, while an increased latent heat flux of I W m-2 was reflected in almost identical changes over the whole region. In addition, the mean annual runoff simulated by CLM4 using MICL data decreased by 6.8 mm yr-1, primarily due to large simulated decreases in humid regions. 相似文献
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Integration of Multi-source Measurements to Monitor Dust over North China：A Case Study 总被引：1，自引：0，他引：1
The aerosol optical depth （AOD） data from the Moderate Resolution Imaging Spectroradiometer （MODIS） aboard Satellite Aqua, along with the altitude-resolved aerosol subtypes product from the Cloud-Aerosol LIdar with Orthogonal Polarization （CALIOP）, as well as surface PM 10 measurements, were utilized to investigate the dust activities common in springtime of northern China. Specifically, a dust storm episode that occurred over the North China Plain （NCP） during 17-21 March 2010 was identified. The PM 10 concentration at Beijing （39.8 °N, 116.47 °E） reached the peak value of 283 μgm -3 on 20 March 2010 from the background value of 15 μg m-3 measured on 17 March 2010, then dropped to 176 μgm-3 on 21 March 2010. Analysis of the CALIOP aerosol subtypes product showed that numerous large dust plumes floated over northern China, downwind of main desert source regions, and were lifted to altitudes as high as 3.5 km during this time period. The MODIS AOD data provided spatial distributions of dust load, broadly consistent with ground-level PM 10 , especially in cloud free areas. However, inconsistency between the MODIS AOD and surface PM 10 measurements under cloudy conditions did exist, further highlighting the unique capability of the CALIOP lidar. CALIOP can penetrate the cloud layer to give unambiguous and altitude-resolved dust measurements, albeit a relatively long revisit period （16 days） and narrower swath （90 m）. A back trajectory simulation using the Hybrid Single-Particle Lagrangian Integrated Trajectory （HYSPLIT） model was performed, and it was found that the sand-dust storm originated from the Gobi Desert on 18 March 2010 travelled approxi-mately 1200-1500 km day-1 eastward and passed over the NCP on 19 March 2010, in good agreement with previous findings. In addition, the multi-sensor measurements integrated with the HYSPLIT model output formed a three-dimensional view of the transport pathway for this dust episode, indicating that this episode was largely associated with the desert source regions to the northwest of the NCP. The results imply the importance of integration of multi-sensor measurements for clarifying the overall structure of dust events over northern China. 相似文献
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Trends in six indices of precipitation in China for seasons during 1961-2007 were analyzed based on daily observations at 587 stations. The trends were estimated by using Sen＇s method with Mann-Kendall＇s test for quantifying the significance. The geographical patterns of trends in the seasonal indices of extremes were similar to those of total precipitation. For winter, both total and extreme precipitation increased over nearly all of China, except for a small part of northern China. Increasing trends in extreme precipitation also occurred at many stations in southwestern China for spring and the midlower reaches of the Yangtze River and southern China for summer. For autumn, precipitation decreased in eastern China, with an increasing length of maximum dry spell, implying a drying tendency for the post-rainy season. Wetting trends have prevailed in most of western China for all seasons. The well-known ＇flood in the south and drought in the north＇ trend exists in eastern China for summer, while a nearly opposite trend pattern exist for spring. 相似文献
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Tides and Wind-Driven Circulation in the Tropical and Southern Atlantic Ocean:The BRAZCOAST System 下载免费PDF全文
下载免费PDF全文 The Brazilian coast is characterized by dif- ferent tidal regimes and distinct meteorological influ- ences. The northern part has larger tidal amplitudes and is permanently affected by trade winds and tropical distur- bances; the southern portion has smaller tidal amplitudes and is frequently influenced by extratropical cyclone ac- tivity. Besides these aspects, many features regarding current structure and behavior are also present, such as the equatorial system of currents, the subtropical gyre and the corresponding western boundary currents, and the Bra- zil-Malvinas confluence region. Within this context, ef- forts were made to develop the BRAZCOAST system, capable of describing the processes that determine the oceanic circulation from large to coastal scales. A cus- tomized version of the Princeton Ocean Model （POM） was implemented in a basin-scale domain covering the whole of the tropical and southern Atlantic Ocean, with 0.5° spatial resolution, as well as three nested grids with （1/12）° resolution covering the different parts of the Bra- zilian shelf, in a one-way procedure. POM was modified to include tidal potential generator terms and a par- tially-clamped boundary condition for tidal elevations. The coarse grid captured large-scale features, while the nested grids detailed local circulations affected by bathymetry and coastal restrictions. An interesting aspect at the coarse grid level was the relevance of the Weddell Sea to the location of the tidal amphidromic systems. 相似文献
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In May 2008, ScienceWatch.com named Advances in Atmospheric Sciences a Rising Star among Geosciences journals. According to Essential Science IndicatorsSM from Thomson Reuters, the journal＇s cur-rent citation record includes 764 papers cited a total of 1,658 times between January 1, 1998 and February 29 2008. 相似文献