求翻译：请输入您需要翻译的文上海地区一般雨量站的观测的雨量资料长度在50年以下，自动记录的雨量资料往往不足30年，并且这些资料中还含有特大值。根据这些雨量资料，在进行短历时暴雨频率分析，推求含有特大值的百年一遇或其它稀遇的设计频率时，任意性较大。如通过调查、考证，合理确定特大暴雨的重现期，这样可以提高了暴雨系列样本的代表性，使计算成果更加合理、可靠，就像在频率曲线的上端增加了一个控制点。是什么意思？

Please enter the text Shanghai area you need to translate the general observations of rainfall stations rainfall data length of less than 50 years, automatically recording the rainfall data is often less than 30 years, and King also contains the value of these data. These rainfall data during short-

Please enter the text you need to be translated in Shanghai General rainfall station of the observation of the rainfall information in length 50 of the following, and automatically record rainfall information is often less than 30 years, and these materials also contain King Size value. In accordanc

Please enter the text you need to translate general observations of rainfall station in Shanghai area rainfall information for lengths under 50 years of age, automatically record rainfall information is often less%2