共查询到20条相似文献，搜索用时 109 毫秒
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利用1966—2018 年海南岛18个台站逐日降水和高温资料,对海南岛西南部干旱与高温进行相关分析。结果表明:海南岛西南部4—6月高温、干旱的空间分布较为相似,西南部高温多,也是干旱的易发地;降水极端偏少年与高温日数的极端偏多年有较好的一致性,均出现重大干旱灾害,这说明高温过程的出现会加重气象干旱的发展。利用NCEP/NCAR再分析资料对比分析4—6月极端旱年和涝年大气环流异常特征,发现阻塞高压、东亚大槽和阿留申低压偏弱,南亚高压偏强,海南岛上空为反气旋式异常环流,高层辐合、低层辐散,是造成4—6月海南岛西南部高温干旱的异常环流背景。 相似文献
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对平乐站1957～2003年夏季实况资料进行分析,阐述了当地夏季高温干旱天气分布概况,分析了夏季高温干旱天气的天气背景。 相似文献
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2013年夏季浙江省高温干旱环流异常分析 总被引：5，自引：4，他引：1
利用浙江省10个站的温度和降水资料、国家气候中心160站的降水资料、NOAA的ERSST和OLR资料及NCEP再分析资料,对2013年7至8月发生在浙江省的持续高温干旱天气过程的基本特征和环流异常进行了分析。结果表明:浙江省各站的高温日数、高温持续日数、持续无降水日数、干旱指数都远超历史同期纪录,降水较常年偏少3成以上。南亚高压强度偏强,面积偏大,东侧脊点位置偏东;西太平洋副高强度偏强,西侧脊点位置偏西;东亚季风异常偏强及其造成的水汽辐合偏弱,是高温干旱天气产生的重要原因。其中7月底西太平洋副高的异常西伸及8月异常持续偏西对浙江8月持续高温干旱的发生起了决定性作用,这与同期热带西太平洋暖池区增暖、菲律宾周围对流活动加强有关,后者通过EAP/PJ遥相关型对前者产生影响。 相似文献
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2009年盛夏湖南持续高温干旱及同期大气环流异常分析 总被引：3，自引：0，他引：3
利用湖南省97个台站降水、气温资料、NCEP/NCAR再分析资料,分析了2009年8月湖南持续高温干旱的时空分布及同期大气环流的异常特征。结果表明:高温时段从8月中旬初开始一直持续到下旬后期,其中8月中旬到下旬高温范围和持续时间大部分地区为1959年以来最严重的时段。西太平洋副热带高压面积偏大、强度偏强、西伸脊点偏西,湖南地区在副高控制下,盛行下沉气流是引起持续高温干旱的直接原因。从南海到湖南地区存在经向水汽输送的负异常中心,这种水汽输送形势有利于持续高温干旱的发展。 相似文献
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2013年夏季湖南严重高温干旱及其大气环流异常 总被引：2，自引：0，他引：2
利用湖南省97个台站降水、气温资料和NECP/NCAR再分析资料以及NOAA卫星观测的OLR场资料,系统分析了2013年6月30日至8月14日湖南持续高温干旱的时空分布及同期大气环流异常特征。结果表明：2013年夏季是湖南1951年以来降水最少、高温干旱程度最严重的一年。西太平洋副热带高压强度偏强、西伸脊点偏西,湖南处在副高控制下,盛行下沉气流是发生持续高温干旱的直接原因;西太平洋副高内增强的下沉气流,致使多数县市高温日数和极端高温突破历史同期最高记录。位于菲律宾附近的OLR低值带中心偏西,致使副热带地区下沉区偏西,进而造成西太平洋副高偏强偏西。此外,湖南地区上空为水汽输送异常辐散中心,这在一定程度上促使了干旱的发生发展。 相似文献
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平乐县夏季高温干旱天气的天气气候背景分析 总被引：3，自引：1，他引：3
对平乐站1957～2003年夏季实况资料进行分析，阐述了当地夏季高温干旱天气分布概况，分析了夏季高温干旱天气的天气背景。 相似文献
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入夏,最高温度的出现,持续时间以及干旱问题,是人们在生产和日常生活中十分关心的问题、特别是对桐乡县来说1988、1990年都出现了严重的高温干旱,7月份的高温(≥35℃)日都在20天以上,蒸发量在200mm 以上。本文就本县的情况,利用1988～1991的资料和预报经验,谈谈高温干旱关键期预报的一些体会。 相似文献
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Sukanta Kumar Das Sanjib Kumar Deb C. M. Kishtawal P. K. Pal 《Theoretical and Applied Climatology》2012,109(1-2):81-94
Seasonal prediction of Indian Summer Monsoon (ISM) has been attempted for the current year 2011 using Community Atmosphere Model (CAM) developed at the National Centre for Atmospheric Research (NCAR). First, 30?years of model climatology starting from 1981 to 2010 has been generated to capture the variability of ISM over the Indian region using 30 seasonal simulations. The simulated model climatology has been validated with different sets of observed climatology, and it was observed that the simulated climatological rainfall is affected by model bias. Subsequently, a bias correction procedure using the Tropical Rainfall Measuring Mission (TRMM) 3B43 rainfall has been proposed. The bias-corrected rainfall climatology shows both spatial and temporal variability of ISM satisfactorily. Further, four sets of 10-member ensemble simulations of ISM 2009 and 2010 have been performed in hindcast mode using observed sea surface temperature (SST) and persistence of April SST anomaly, and it has been found that the bias-corrected model rainfall captures the seasonal variability of ISM reasonably well with some discrepancies in these two contrasting monsoon years. With this positive background, the seasonal prediction of ISM 2011 has been carried out in forecast mode with the assumption of persistence of May SST anomaly from June through September 2011. The model assessment shows an 11% deficiency in All-India Rainfall (AIR) of ISM 2011. In particular, the monthly accumulated rains are predicted to be 101% (17.6?cm), 86% (24.3?cm), 83% (21.0?cm) and 95% (15.5?cm) of normal AIR for the months of June, July, August and September, respectively. 相似文献
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Distribution of convective energy at upper level in South Korea and the possibility of artificial showery rain caused by activated CAPE 总被引：1，自引：0，他引：1
This paper reports a theoretical study on the possibility of inducing artificial showery rain using the convective available potential energy, which is naturally stored in the troposphere. We calculated the environmental parameters (frequency of climatic values, extreme value of stability index, etc.) in the upper troposphere using rawinsonde data from six main stations in Korea from 2001 to 2008 and examined the temporal spatial convective energy according to region. Our results showed that convective available potential energy, which can induce artificial rainfall, existed in the troposphere mainly in summer and were low in other seasons. Its value was found to be highest during late afternoon and in inland regions. We examined the vertical structure of the atmosphere using moisture convergence and vertical velocity (omega) and found that precipitation occurred under strong real latent instability conditions with high convective available potential energy (>3,000?J/kg) in summer and was characterized by moisture convergence at 1,000?C400?hPa, moisture divergence at 400?C300?hPa, and continuous ascending air current at 1,000?C300?hPa (?C??), on average. However, precipitation still did not occur in more than half the cases with high convective available potential energy because, according to the analysis, convective rainfall is affected to a greater extent by the value of convective inhibition than by convective available potential energy. It was also verified that in spite of zero convective inhibition, if the updrafts at a lower level were not sufficient to generate high convective available potential energy at a level higher than the level of free convection, convective rainfall would not occur under real latent instability. Therefore, we suggest it might be possible during the summer to secure the water resources in regions without precipitation by inducing ascending air current artificially under unstable atmospheric conditions to induce showery rain. 相似文献
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Summary Ground-based spectroradiometric measurements obtained in Athens have been used in order to derive the aerosol optical depth
and the ?ngstr?m parameters. Their derivation is achieved using three well-established and widely used techniques; the Volz
method, the direct method and the least-squares fit to the experimental aerosol optical depth values. This study aims at investigating
the ability of the different methods to derive similar ?ngstr?m turbidity coefficients and their dependence on the spectral
range used for their determination. In addition, the uncertainties revealed especially in the UV spectral band are highlighted.
The various techniques lead to different ?ngstr?m turbidity coefficients especially if narrow spectral bands at the shorter
wavelengths are used. It is also established that the ?ngstr?m turbidity coefficients derived by any of the three methods
at short wavelengths are not representative of the whole spectrum, while their derivation exhibits large uncertainties especially
under low turbidity conditions. Therefore, the comparison of α and β values obtained using the three above-mentioned techniques
in several spectral bands is not an easy task, since these values differ significantly. From the whole analysis it is established
that the least-squares method is the least imprecise, also exhibiting the least wavelength dependence.
Correspondence: Dimitris G. Kaskaoutis, Institute for Environmental Research and Sustainable Development, National Observatory
of Athens, Lofos Nymphon, P.O. Box 20048, 11810 Athens, Greece 相似文献
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This study provides a multi-site hybrid statistical downscaling procedure combining regression-based and stochastic weather generation approaches for multisite simulation of daily precipitation. In the hybrid model, the multivariate multiple linear regression (MMLR) is employed for simultaneous downscaling of deterministic series of daily precipitation occurrence and amount using large-scale reanalysis predictors over nine different observed stations in southern Québec (Canada). The multivariate normal distribution, the first-order Markov chain model, and the probability distribution mapping technique are employed for reproducing temporal variability and spatial dependency on the multisite observations of precipitation series. The regression-based MMLR model explained 16?%?~?22?% of total variance in daily precipitation occurrence series and 13?%?~?25?% of total variance in daily precipitation amount series of the nine observation sites. Moreover, it constantly over-represented the spatial dependency of daily precipitation occurrence and amount. In generating daily precipitation, the hybrid model showed good temporal reproduction ability for number of wet days, cross-site correlation, and probabilities of consecutive wet days, and maximum 3-days precipitation total amount for all observation sites. However, the reproducing ability of the hybrid model for spatio-temporal variations can be improved, i.e. to further increase the explained variance of the observed precipitation series, as for example by using regional-scale predictors in the MMLR model. However, in all downscaling precipitation results, the hybrid model benefits from the stochastic weather generator procedure with respect to the single use of deterministic component in the MMLR model. 相似文献
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利用NCEP再分析资料、ECWMF预报风场和历史降水量资料,分别采用前人提出的相似量和本文改进的相似量进行动力相似选择试验。结果表明:改进后的相似量的相似选择效果最好。对于南充2012年7月4日区域大暴雨过程,用改进相似量筛选出与此次过程最相似的历史个例,进行对比分析后,发现最相似个例风场与预报风场在形状、强度和影响系统空间配置都很相似,降水实况接近。表明最相似个例的风场和降水资料对该次大暴雨过程的降水量级、落区预报有较高的参考和指示意义。 相似文献
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J.R. Philip 《Boundary-Layer Meteorology》1997,84(1):85-98
Previous studies of blending heightsfor scalars, using periodic solutions of atmosphericconvection-diffusion equations, raise two questions. 1. What is the relation between growth of the internalboundary-layer height downwind of a step in surfaceconditions, and the increase of blending height withdownwind pattern wavelength? 2. Can the approach beextended to shear stress? The answers are: 1. Thedependence of boundary-layer height on fetch has thesame functional form as that of blending height onwavelength; but it is greater by a factor of about1.9. 2. Representing eddy diffusivity as the productof mean windspeed and a power of height gives a linearhorizontal momentum equation. A further approximationgives a convection-diffusion equation for shearstress, analogous to those used previously forscalars. 相似文献
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MOS预报最优子集模型,通过消除数值模式系统性误差,可最大程度地提高其预报技巧。为了建立Na?ve Bayes降水最优模型,利用2008—2011年T511数值预报产品和单站观测资料,对介休、运城、丰宁3个站Na?ve Bayes降水概率分级预报模型进行研究。通过设计恰当的适应度函数,提出了一种用遗传算法搜寻Na?ve Bayes模型最优子集的计算方案,得到了3个站的最优子集模型。结果表明:最优子集的拟合效果明显高于普通初始子集,能够显著提升数值模式在单站的预报技巧。最优子集模型主要通过降低数值模式空报率提高单站晴雨、小雨预报效果,通过小幅提高正确次数和降低空报次数改善对中雨预报效果。 相似文献
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Surface solar radiation (SSR) can affect climate, the hydrological cycle, plant photosynthesis, and solar power. The values of solar radiation at the surface reflect the influence of human activity on radiative climate and environmental effects, so it is a key parameter in the evaluation of climate change and air pollution due to anthropogenic disturbances. This study presents the characteristics of the SSR variation in Nanjing, China, from March 2016 to June 2017, using a combined set of pyranometer and pyrheliometer observations. The SSR seasonal variation and statistical properties are investigated and characterized under different air pollution levels and visibilities. We discuss seasonal variations in visibility, air quality index (AQI), particulate matter (PM10 and PM2.5), and their correlations with SSR. The scattering of solar radiation by particulate matter varies significantly with particle size. Compared with the particulate matter with aerodynamic diameter between 2.5 μm and 10 μm (PM2.5?10), we found that the PM2.5 dominates the variation of scattered radiation due to the differences of single-scattering albedo and phase function. Because of the correlation between PM2.5 and SSR, it is an effective and direct method to estimate PM2.5 by the value of SSR, or vice versa to obtain the SSR by the value of PM2.5. Under clear-sky conditions (clearness index ≥0.5), the visibility is negatively correlated with the diffuse fraction, AQI, PM10, and PM2.5, and their correlation coefficients are ?0.50, ?0.60, ?0.76, and ?0.92, respectively. The results indicate the linkage between scattered radiation and air quality through the value of visibility. 相似文献
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1INTRODUCTIONTropicalwesternPacificOceanisanareathathasthehighestoceantemperatureacrosstheglobe.Asmostofthewarmwaterconcentratesintheregion,itisknownasthe搘esternPacificwarmpool?Asshowninsomestudies[1-5],thegeneralcirculationandshort-termclimaticchangeswillbeseriouslyaffectedifthermodynamicconditionchangesinthewaters,whichthenhaveanimportantroletoplayintheonsetofanyENSOepisodes.Therehasnotbeenanyunifieddefinitionoftheindexforthewarmpool.FollowingthecriterionofWyrtki[4],however,theareae… 相似文献
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Rakhyun E. Kim 《Global Environmental Change》2013,23(5):980-991
The conventional piecemeal approach to environmental treaty-making has resulted in a ‘maze’ of international agreements. However, little is known empirically about its overall structure and evolutionary dynamics. This study reveals and characterizes the evolving structure of the web of international environmental treaty law. The structure was approximated using 1001 cross-references among 747 multilateral environmental agreements concluded from 1857 to 2012. Known network analysis measures were used to answer the following questions: has a complex system of international environmental treaty law emerged? If so when, and what does it look like? What are its topological properties? To what extent is the institutional complex fragmented? The network analysis suggested that multilateral environmental agreements have self-organized into an interlocking system with a complex network structure. Furthermore, the system has defragmented as it coevolved with the increasing complexity and interconnectivity of global environmental challenges. This study demonstrates the need to approach multilateral environmental agreements in the context of a complex networked system, and recommends against assuming the overall institutional structure is fragmented. Proposals for global environmental governance reform should pay attention to this network's emergent polycentric order and complexity and to the implications of these features for the functioning of the multilateral environmental agreement system. 相似文献