Abstract: To obtain accurate hail information more easily and quickly, a three-level identification is designed, which is the first identification of microblog containing “hail” through Web crawler technology, the second identification of hail events based on classifier and the third identification of hail element information based on rules. In order to improve identification performance of hail events, an assessment function for extracting features is added, and a multi-assessment function to determine the feature vectors is proposed. Then a scheme based on combination of three classifiers is given. The test results show that hail events extraction rate is 89.5% by the presented method, mistaken identification rate is less than 13.4%; hail element information extraction rate is more than 96.0%, mistaken identification rate is less than 8.6%.

Key words: microblog, hail information, feature extraction, text classification, text elements recognition, Web crawler