Abstract:
As a new type of detection instrument, wind profile radar (WPR) can detect meteorological factors such as wind profiles. The special detecting ability of WPR decides its broad application in atmospheric science research, climate research, meteorological operation application, aviation security and many other areas. Data quality control and accuracy of WPR for application of comprehensive developing meteorological operation has the vital significance.Based on basic data of WPR and meteorological background information, a new method of evaluating wind measurement precision of WPR is proposed. Combined with PB-type Ⅱ troposphere WPR detection data from Yanqing Meteorological Observatory of Beijing, the feature of WPR data is analyzed, processing all continuous observation data of four months (March, June, September and December) of 2010, except for some missing measurements. According to rain gauge data hour by hour, all data are divided into two categories: Clear sky and rainfall, rainfall data are extended to five hours before and after the precipitation. Yanqing is located in the north mountain areas of Beijing, few days of precipitation are observed by WPR site, only 15 times in all. A total of 34380 individual observation cycle data of clear sky and 2580 individual observation cycle data of rainfall are statistically analyzed, respectively.Results show that the maximum height is 8 km in June and September, 6 km in March and December when the velocity error is less than 1.5 m·s
-1, and the wind direction error is less than 10°, which basically meets the design requirements of the radar detection height. Quality of radar return signal and inhomogeneity of atmosphere are the two influencing issues for wind measurement accuracy of radar.Signal quality directly affects the detection height, and the SNR (signal to noise ratio) of radar return signal has influences on wind measurement precision on the upper air, where -15.0 dB of SNR can be judged as the threshold of maximum detection height of radar wind measurement reliability. Inhomogeneity of atmosphere underclear air conditions affects the precision of wind measurement slightly.Larger errors of horizontal wind direction and speed appear when it rains, making the wind accuracy unacceptable especially. 1 or 2 hours before the convective precipitation, horizontal wind direction and speed of the variance increase rapidly, which could be a sign of strong precipitation.This new method and the evaluating approaches have the following advantages: Four groups of three-beam detected pattern are used to evaluate effective detected height and accuracy of wind measurement under clear sky conditions.The wind levels are determined through the threshold value combined horizontal speed and direction.The thresholds are based on different months and different heights under clear air conditions.The influences of wind measurement precision are given by analyzing two different types of precipitation.Inhomogeneity of atmosphere is found obviously before rainfall, which can be seen as a warning indicator before strong precipitation.