福建沿海平原和山地地区的雨滴谱差异研究

A study on the difference of raindrop spectra between coastal plain and mountain areas in Fujian Province

中文关键词:  雨滴谱，山地和平原，经验关系，雷达定量降水估测

英文关键词:Raindrop size distribution, Mountain and plain sites, Empirical relations, Radar quantitative precipitation estimation

中文摘要:

      为研究福建沿海平原和山地两个地区降水的微物理特征和差异，利用2018–2022年福建泉州晋江站（平原站）和九仙山站（山地站）的雨滴谱资料，从整体统计、不同降水强度和不同降水类型等角度，研究了两个不同地区的雨滴谱特征和差异，并对两个地区的雷达观测量与雨强的经验关系进行了研究和初步检验。结果表明：福建沿海山地站的小雨滴（直径D＜1 mm）和大雨滴（D≥3 mm）数浓度明显高于平原站，但平原站的中雨滴（1≤D＜3 mm）数浓度则略高于山地站。两个站的小雨滴数浓度随着雨强增大呈现“先增加、后减小、再增加”的趋势，而中大雨滴的数浓度则随雨强的增大也持续增大。山地站降水整体具有更小的质量加权平均直径（Dm）和更大的广义截断参数（log10Nw）。因更多中大雨滴的贡献，平原站的雨滴谱在相同形状参数（μ）下，形状参数（Λ）较山地站更小，即雨滴数浓度随直径增大而下降的速率更慢。对两个站雨滴谱拟合得到的雷达定量降水估测公式进行初步检验，结果表明，实测雨滴谱拟合的反射率因子与降水强度（Z–R）关系和差分传播相移率与降水强度（Kdp–R）关系效果均好于现阶段我国业务常用的Z–R关系。

英文摘要:

      In order to study the microphysical characteristics and differences of precipitation in Fujian coastal plain and mountainous area, this paper uses the raindrop distribution observation data of the Jinjiang station (plain aera) and Jiuxianshan station (mountainous area) in Quanzhou, Fujian from 2018 to 2022. From the overall statistics and the perspective of different precipitation intensities and different precipitation types, the characteristics and differences of raindrop spectrum in the two different areas are studied, and the empirical relationship between radar observation and rain intensity in the two areas is compared. The results showed that the number concentration of small raindrops (diameter D < 1 mm) and large raindrops (D≥3 mm) in the mountain station was significantly higher than that in the plain station, but the number concentration of medium raindrops (1≤D < 3 mm) in the plain station was slightly higher than that in the mountain station. The number concentration of small raindrops in the two stations showed a trend of "first increasing, then decreasing, and then increasing" with the increase of rain intensity, while the number concentration of medium and large raindrops continued to increase with the increase of rain intensity. The mountain station as a whole has smaller mass-weighted mean diameter (Dm) and larger normalized intercept parameter (log10Nw), the standard deviation of both Dm and log10Nw is lower for the plain station than for the mountain station. Since the plain station has more medium and large raindrops, the slope parameters (Λ) value of the mountain station is higher than that of the plain station for the same shape parameters (μ), that is, raindrop number concentration decreases more slowly with increasing diameter. Preliminary examination of the radar quantitative precipitation estimation formulas obtained by fitting the raindrop spectra at the two stations shows that the reflectivity factor-precipitation intensity (Z–R) relationship and the specific differential phase-precipitation intensity (Kdp–R) relationship fitted to the measured raindrop spectra are both better than the Z–R relationship commonly used in China"s operations at this stage.