为适应地面气象观测业务调整方向，提高新型自动气象站观测资料的质量及可用性，研究中对天津地区10个地面气象站1951—2014年历年2月人工观测及2014年2月自动观测和人工观测的轻雾、雾、霾现象进行对比评估。结果表明：天津地区历年2月轻雾的平均日数为10 d，雾和霾均为2 d，轻雾和霾同期出现的日数占有天气现象的7．4％，而雾和霾同期出现日数仅占0．7％；平行观测期的对比分析得到人工观测轻雾日数比自动观测多11 d，雾日数和霾日数均比自动观测少6 d，其中，轻雾和雾的判别差异集中出现在每日08：00（北京时，下同），霾则基本出现在每 日08：00，14：00，17：00，20：00；通过对比自动观测和人工观测的能见度数据发现，二者相对偏差达25．1％，能见度小于15．0 km 时，自动观测的能见度有60％～76％数值偏小，特别是08：00和20：00，因此，在相对湿度满足条件的情况下，能见度的判别误差是导致自动观测与人工观测轻雾、雾、霾现象判别差异的重要原因。%Based on the past records by manual observation at ten meteorological stations during 1951-2014 and parallel observations by automatic and manual observations in February 2014,discrepancies of mist,fog and haze phenomena are evaluated in Tianjin,in order to meet the reform direction of surface meteorologi-cal observation business,and to improve the quality and availability of data observed by new automatic sys-tem.Results indicate that in February,the mean number of mist days in Tianjin is 10,while numbers for fog or haze days are both 2.The proportion for mist accompanying haze days occupies 7.4% in all the weather phenomena,but for fog and haze days,it is only 0.7%.There is an increasing trend in mist days, but not for fog,and since 1990s,haze days have begun to increase obviously,especially for the year of 2007 during the last 60 years.Comparative analysis in parallel period by manual indicates there are 11 more mist days but 6 less fog and haze days than those by automation.Discrepancies of mist and fog phenomena arise at 0800 BT,manual observation captures more mist but automatic observation records more fog.Dis-crepancies of haze phenomenon arise at 0800,1400,1700 BT and 2000 BT,which are observed by manual way,but none according to automatic observations,while the phenomena of haze or mist and haze are to-tally the opposite.However,characteristics of phenomena judged by automatic and manual observations are of the same,i.e.,mist days are the most,haze days are the second,fog days are the least,and the number of mist accompanying haze days is more than that for fog accompanying haze.Comparing visibility values by manual observation with automation indicates that the average relative error between them is 25.1% in all the samples,54.5% of automatic observation is less than manual observation,28.5% out of these the difference exceeding 1 km,manual observation meets with automatic observation only for 6.5%of all cases.For differences of visibility in different order of magnitude,60%-76% of automatic observa-tion is smaller,when the visibility is less than 15.0 km,especially for 0800 BT and 2000 BT.The median of relative error within the threshold ranges of [1.0 km,5.0 km)and [5.0 km,10.0 km),judging the phe-nomenon of mist and haze,are both about 22%,and larger range of [10.0 km,15.0 km)and [15.0 km,+∞)are only about 15%.Accordingly,observation error of visibility is an important cause leading to dis-crepancies of mist,fog and haze phenomena by automatic and manual observations,in the case of relative humidity to meet suitable conditions.
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