利用浙江省中尺度自动站的温度资料, 引入已广泛应用于测绘、 地球物理、 地图绘制等领域的Multiquadric插值法, 并与目前气象领域内采用较多的Cressman方法进行比较, 分析两者在不同站点分布和数量下对实况场的逼近程度, 并对Multiquadric中的自由设定参数进行讨论。结果表明, 总体而言, Multiquadric方法的均方根误差小于Cressman方法。当站点数为100时, 两者差异达0.3℃; 当站点数>1000时, Multiquadric方法相对Cressman的改进已经<1%, 两者差异非常小。在站点数较少或是站点间隔较大的情况下, Cressman方法较易产生虚假中心, 而Multiquadric方法则更加接近实况。Multiquadric平滑参数λ可以被认为是一种低通滤波器, 它将高频波滤去, 留下较大尺度的系统, 同时冷暖空气温度中心的强度随着平滑强度的增加也逐渐减弱。Multiquadric参数c存在一个上限值, 当c大于或小于该值时, 客观分析结果表现出不同的敏感度。
Objective analysis of mesoscale meteorological data has an important role in real time monitoring and diagnostic analysis. The Cressman method is very popular in meteorology.The Multiquadric method has been widely applied in geodesy, geophysics, geography and surveying and mapping problems. The Multiquadric method is compared to the Cressman method by using conventional observations and variable number of mesoscale automatic observationsto analyze the approximate extent to real data with different datadistribution and quantity.The results indicate that: The root mean squared error of the Multiquadric method is less than that the Cressman method. The difference between these two methods gradually diminishes with the increasing number of observations for objective analysis. When the distancebetween two observations is large or few observations are used, the Cressman method tends to produce untrue centers while the analytical field by using the Multiquadric method is more closer to observations. Multiquadric smoothing parameter λ is regarded as a low-pass filter which screens high frequency waves and preserves large scale systems. The intensity of temperature centers gradually diminishes with increasing λ. The multiquadric parameter c has an upper limit. When c is greater or less than the threshold, the analytical result shows different sensitivities.
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