Data Evaluation and the Advantage of the Double Automatic Weather Stations

Anhui Provincial Meteorological Service starts pilot run of double automatic weather stations at national weather stations in 2010. The stations are deployed in Xiuning, Anqing, Kuche and other districts, and they have been put into test run one after another since October of 2010. A detailed assessment is carried out to evaluate the hourly data of temperature, air pressure, relative humidity, 2 min average wind speed, 5 cm ground temperature and grass temperature of the double automatic weather stations in Xiuning, Anqing and Qimen from January to August of 2011. At the same time, the advantages and disadvantages of the double automatic weather stations are discussed.The data integrity of the double automatic weather stations is analyzed by calculating missing rate. The missing rate of air pressure of Station A is 0.38%, and Station B is 0.15% in Xiuning, but rate of Station A and B both missing at the same time is only 0.07%. So it is considered that the double automatic weather stations can reduce missing rate, and ensuring the integrity of data. The difference of the double sets of data is discussed by the statistical features, consistent rate, rate of gross errorand out-of-tolerance rates. Through the detailed analysis, it shows that most elements (such as temperature, air pressure and relative humidity) of the double automatic weather stations have stable and smaller difference.For example, the average air pressure of station A is lower than station B in Anqing, with the difference of 0.01 hPa. In 5812 effective samples of difference data, there are 1659 samples with difference of 0.0 hPa, and for 99.2% of all the samples, differences are within ±0.1 hPa. The standard deviation of difference is 0.08 hPa.The difference has higher concordance rate, lower out-of-tolerance rates and lower gross error. For example, the consistency rate of temperature is 96.6% in Qimen, the out-of-tolerance rates of humidity is 0.0% in Xiuning, the gross error rate of air pressure is 0.0% in Anqing. However, some elements of the double automatic weather stations have lager difference, such as the grass surface temperature and ground temperature. For example, the gross error of grass surface temperature is 12.7% in Xiuning, and the out-of-tolerance rate of ground temperature is 29.7% in Anqing.The data evaluation shows that the abnormal data, instrument systematic error can be found through monitoring the difference and the moving average of difference data, and whether the instruments have significant changes in performance can be determined by the daily change characteristic difference data of the double data. Thus, the double automatic weather stations have the potential advantages of ensuring the quality of data, and resolve the deficiency of current automatic stations in some degree in operation.