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利用地面辐射计作为雷达定量测量降水的一种补充手段,是近年来刚刚发展起来的方法。中国科学院大气物理研究所在1980年研制了8mm和3.2cm的雷达一辐射计联合系统,进行了一些实测试验,并提出了这种联合系统测量降水的求解方案。本文通过数值实验方法,对3.2cm波段上的这种方法以及另两种雷达测雨的求解方法进行系统的考察和比较,对每种方法由各种因子引起的误差进行了初步讨论,从而对三种求解方法的实际可行性得出一些有意义的结论。 相似文献
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雨量计可以直接测量单点雨强随时间的连续变化 ,测量精度较高 ,但雨量计站网的密度不够 ,往往漏掉强降水、暴雨中心 .雷达能实时探测云和降水结构及系统发生、发展演变情况 ,能迅速提供一定区域的实时降水情况 ,但雷达测量误差较大 ,测定局地降水量精度不高 ,因此雨量计和雷达进行点面结合 ,采用一定的数学方法将雨量计单点测量精度较高和雷达能测量降水时空分布的优点结合起来 ,利用雨量计测量校准雷达定量测量降水 ,可获得比单纯用雷达方法在精度上有很大提高的降水测量结果 .1 变分法校准雷达定量估测降水的原理将雷达探测区网格化 ,在… 相似文献
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雨量计可以直接测量单点雨强随时间的连续变化,测量精度较高,但雨量计站网的密度不够,往往漏掉强降水、暴雨中心.雷达能实时探测云和降水结构及系统发生、发展演变情况,能迅速提供一定区域的实时降水情况,但雷达测量误差较大,测定局地降水量精度不高,因此雨量计和雷达进行点面结合,采用一定的数学方法将雨量计单点测量精度较高和雷达能测量降水时空分布的优点结合起来,利用雨量计测量校准雷达定量测量降水,可获得比单纯用雷达方法在精度上有很大提高的降水测量结果. 相似文献
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WSR—88D算法和产品改进的用户反馈信息 总被引:4,自引:0,他引:4
WSR-88D(WeatherSurveillanceRadar1998,Doppler),即美国1988年定型生产的下一代天气雷达,是目前美国全国天气雷达网的布点雷达。该雷达是全相干体制的多普勒天气雷达,它不但具有常规天气雷达扭具备的可以观测降水回波强度分布的特点,而且还能获得云体内部风场分 结构信息,是研究强对汉等中小尺度天气系统的有力工具。1998年上海市气象局从美国引进了一部WSR-88D 相似文献
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新一代天气雷达定量降水估测集成系统 总被引:10,自引:6,他引:4
降水的定量测量是天气雷达的重要应用之一,新一代天气雷达定量降水估测集成系统(QPEGS)是一套基于新一代天气雷达的雷达雨量计联合估测降水软件,利用多种雨量计校准雷达降水的方法,生成1小时降水分布。其产品的时间分辨率达10分钟,空间分辨率1 km×1 km,适合省市级业务台站使用。过去3年的数据评估表明:校准雨量计数量和估测精度有明显正相关,校准雨量计数越多,降水估测精度越高,2003年的小时降水估测误差约40%,过程降水量的估测误差小于20%;雨量计密度保持不变的情况下,降水时段越长,降水区域越大,降水估测的精度也越高。 相似文献
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基于漂移克里金融合雷达、雨量计定量估测降水研究 总被引:1,自引:0,他引:1
文中介绍了一种新的融合雷达和雨量计数据开展定量估测降水研究的空间信息统计学方法—Kriging with external drift(KED)方法。该方法能很好地融合高精度、低时空分辨率的雨量计数据和低精度、高时空分辨率的雷达数据进行插值。通过变异函数描述降水场的空间结构信息,能够充分利用数据间的空间相关性,来改进估测精度和提高处理速度。利用其优良的数学特性,以期在定量估测降水业务研究上进行新的探索和尝试。选用湖南省有代表意义的3次降水过程资料,通过雷达直接估测降水(RAD)、变分校准(VAR)以及KED 3种方法,分别与雨量计测量值进行对比分析,选用代表站进行交叉验证结果均表明:RAD的均方差、绝对误差、相对误差最大,VAR次之,而KED最小。KED估测的结果与雨量计测量降水最为接近,估测效果最好;3种方法与雨量计实测值计算一定范围的误差频率,KED估测值具有最小的均方差和最小的标准差,且误差分布相对集中在0值附近,斜度和峰度最佳,试验证明该方法不仅能提高降水估测精度,且优于其他方法,VAR均方差次之,RAD均方差效果相对较差。联合雷达、雨量计估测降水的实质是把雷达估测值与雨量计测量的结果相融合,以雨量计来校准雷达估测值,保留了雷达探测到降水的中、小尺度精细特征。校准后的雨量场数值接近雨量计测值,而且能够准确反映雷达测得的降水分布形式。 相似文献
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于洪君 《南京气象学院学报》2020,12(3):322-329
本文提出了在有限的感知范围内,提高二维空间中移动网络的拓扑鲁棒性和连接鲁棒性的方法.由于移动基站和网络用户的动态不同步,控制策略被假定为异步的.在基于封闭区域重新定义连接的基础上,导出了保持当前网络拓扑的条件,并设计了两种方法来保证在提高拓扑和连接鲁棒性的过程中满足该条件.然后,设计了一种组合方法,给出了网络拓扑保持完整的充分条件.最后,通过数值算例验证了所提方法的有效性. 相似文献
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利用华北平原47个农业气象观测站1986—2010年冬小麦的品种、发育期观测资料和同期气象数据,基于常用的发育期模型,对两种参数化方案下品种变化对发育期影响的特征进行研究。其中参数化方案1采用固定的三基点温度,参数化方案2通过循环优化得到三基点温度。结果表明:在华北平原冬小麦品种变化频繁的情况下,两种参数化方案均能较好地对返青-抽穗期与抽穗-成熟期的模拟过程进行参数化;两种参数化方案均认为品种变化使返青-抽穗期和抽穗-成熟期日数有延长趋势,但不同参数化方案的趋势值存在较大差异,且参数化方案1模拟的趋势值总是高于参数化方案2。此外,不同的参数化方案也会使模拟的趋势值在区域上的分布规律发生变化。研究表明:不同参数化方案的使用会对模拟结果产生明显影响,因此,在量化品种变化对发育期影响时,需关注不同参数化方案对结果的影响,以及由此带来的不确定性。 相似文献
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This paper presents a new method to estimate the height of the atmospheric boundary layer(ABL) by using COSMIC radio occultation bending angle(BA) data. Using the numerical differentiation method combined with the regularization technique, the first derivative of BA profiles is retrieved, and the height at which the first derivative of BA has the global minimum is defined to be the ABL height. To reflect the reliability of estimated ABL heights, the sharpness parameter is introduced, according to the relative minimum of the BA derivative. Then, it is applied to four months of COSMIC BA data(January, April, July, and October in 2008), and the ABL heights estimated are compared with two kinds of ABL heights from COSMIC products and with the heights determined by the finite difference method upon the refractivity data. For sharp ABL tops(large sharpness parameters), there is little difference between the ABL heights determined by different methods, i.e.,the uncertainties are small; whereas, for non-sharp ABL tops(small sharpness parameters), big differences exist in the ABL heights obtained by different methods, which means large uncertainties for different methods. In addition, the new method can detect thin ABLs and provide a reference ABL height in the cases eliminated by other methods. Thus, the application of the numerical differentiation method combined with the regularization technique to COSMIC BA data is an appropriate choice and has further application value. 相似文献
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Different attenuation correction methods for the X-band dual linear polarimetric radar are analyzed in this paper.The specific differential phase shift K DP is always considered as an effective factor in radar signal attenuation correction.However,the values of K DP for light rains are too small,which results in unstable quality and large errors of rainfall estimation.Therefore,radar horizontal reflectivity Z H and specific differential phase shift are combined together in the Z H –K DP method to correct th... 相似文献
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The results of computation of wind wave fields for two versions of the WAM model (the original version of the European wind wave model WAM4 and its modified version WAM4-M) are compared with satellite measurements. The mapped data on the daily averaged wave height obtained from the data of combined measurements of several satellite altimeters are used. Significant correlation between wind wave series for both models and satellite data is demonstrated as well as the advantage of the WAM4-M model over its original version in accuracy and some statistical parameters of comparison with the altimeter. Advantages and shortcomings of numerical and remote sensing methods of wind wave investigation at the ocean scales are noted. 相似文献
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《Atmospheric Research》2009,94(4):673-679
Since climate trends are getting considerable attention in recent years, we aimed in this study to compare trends and rhythms of complexity (fractal dimension, FD) of rainfall data series between two continents: Latin America and Europe. Two parallel nonlinear methods for calculating FD of a temporal data series, Higuchi's and consecutive differences, were combined with Fast Fourier Transform (FFT) to obtain FD oscillations of monthly accumulated rainfall. The data were collected for the last thirty years in Pastaza province, Ecuador and Veneto province, Italy. In order to calculate their FD time dependence, FD(t), moving windows of different lengths (short, 10–20 and long 21–350 samples), were applied. Both methods, each combined with FFT, detected identical (or very similar) rhythms of detrended FD(t) in the two data series, but frequencies with dominant amplitudes differed (4.4 years in Ecuador, 10.3 years in Italy). Long-term FD(t) trends were also studied using optimized long window lengths (~ 200 samples). A linear positive trend was obtained for the Ecuadorian rainfall data over the whole recorded period. Italian fractal trend profile was, however, characterized by two periods: a constant high value for years 1974–1993, followed by a linear decrease for 1993–2005. Trend results, obtained with two different methods, were also similar. Accordance of the results, reported in the present paper by applying these two methods, validates their use as a tool in future fractal meteorological measurements. As well, these results indicate that positive FD trend obtained for Pastaza (Ecuador) and negative trend computed for Veneto (Italy) account for a local or regional phenomenon, most probably caused by extensive deforestation and land use change (Ecuador) and continental or global atmospheric pattern variability (Italy). 相似文献