Gaoyuan qixiang (Dec 2022)
Research on a Quality Control Method for L Band Second-Level Radiosonde toward Assimilation Applications
Abstract
Since 2003， the World Meteorological Organization （WMO） proposed and coordinated a switch from traditional radiosonde format （TAC code） to second-resolution binary （BUFR） report， which leads the assimilation of second radiosonde data in numerical prediction model becoming the future trend.Data quality control is a key and basic work before assimilation application.In addition， the observational error characteristics of Lband second-level radiosonde are significantly different from that of conventional radiosonde.Therefore， a two-step quality control method for assimilation application is developed in this paper.The first step integrates conventional radiosonde quality control procedures and inserts several additional steps according to the data characteristics of second-level radiosonde， which aims at eliminating human-observation errors as much as possible.The second step introduces a dynamic blacklist checking module into the assimilation system， at the same time remaining the old OMB （observation minus background） check method， so as to control the representative deviation between the observation and the model background.By comparing and analyzing the statistical characteristics of the observation samples before and after the quality control procedure， and combining them with the actual assimilation analysis results of the NWP model， the rationality of the two-step quality control procedure has been comprehensively verified.It reveals that the data anomaly is greatly reduced after the two-step quality control procedure， at the same time the OMB is closer to a Gaussian distribution.Moreover， the validity of data assimilation is enhanced leading to a better assimilation analysis effect.The work lays a foundation for the future operational application of L-band second-level radiosonde data in GRAPES （Global/Regional Assimilation and Prediction System） model.
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