A Study On Quality Control And Preliminary Analysis Of Precipitation Characteristics With Ground-based Microwave

The ground-based microwave radiometer which is applied in remote sensing technology is a promising meteorological observation instrument. Compared with conventional radiosonde data, it has a much shorter observation interval and more sufficient atmosphere information. As a result, it can greatly make up the shortcoming of the convnentional radiosonde observation, and it can be more generally applied in remote sensing technology.In order to make better use of the data of ground-based microwave radiometer and ensure the reliability of the information, we select observed brightness temperatures of38clearsky days throughout June, September, and October in2010and the corresponding radiosonde data at20:00pm. After that we use MWCLD radiation transfer model, combined with different frequency characteristics of observation channels to control the quality of the ground-based microwave radiometer data. First, we need to obtain the simulated brightness temperatures of each channel based on the MP-3000A in Wuhan, the radiosonde data are introduced into the radiative transfer model. The selected cases are used to make a comparison of the brightness temperatures between the calculated values by radiative transfer model and observational values by the radiometer. Based on analyzing the consistency of simulated and observed brightness temperatures, the observation rationality of each channel can be judged. The analysis results show an excellent agreement between the simulated and observed brightness temperatures. After deviation corrections or linear correction, these data can be used to check the state of each channel of microwave radiometer, so as to establish a quality control scheme of the ground-based microwave radiometer data effectively.In this paper, we collected the data of atmospheric vapor content (V) and cloud liquid water content (L) one hour before precipitation throughout July, August and September in2009by the MP-3000A of Wuhan after the quality control, combined with meteorological data in historical observations, we further analyzed the distribution and evolution of atmospheric vapor and cloud liquid water one hour before precipitation, as well as their relationship with precipitation, the results showed that:1) one minite before the start of the heavy rain, vapor content value≥6.5cm, the value of V corresponding to moderate rain was close to6cm, the V value corresponding to light rain was between5-6cm;2) the V value exceed to5cm, the L value exceed to lmm could be used as an indicator of close to precipitation;3) one hour before the start of precipitation, the growth of vapor content could be divided into two condition:one grew steadily and the other increased first to a peak and then declined,5-10minutes before precipitation increased again;4) after the removal of background values (we use the mean values of L and V of Clear sky as the background values) of L and V one hour before precipitation we found that the value, fluctuation range and trend of L basically have no change; the value of V and fluctuation range had been reduced, but the fluctuation trend had no significant change;5) after the Fast Fourier Transform, V and L value showed different characters in the first turning point could be used as an indicator of approaching precipitation;6) the change of the near ground water vapor density profile can provide some references for precipitation.