为了准确地描述悬浮颗粒物粒径的分布特征,探索高精度的悬浮颗粒物粒径分布模拟,本文基于2014年11月黄、渤海的现场悬浮颗粒物粒径数据,研究了幂律模型在黄、渤海的适用性;同时,参考粒径作为幂律模型的重要参数,影响着幂律模型的斜率(颗粒粒径分布斜率)和模拟精度,因此对不同参考粒径下幂律模型的斜率变化情况以及模型模拟精度也进行了分析。结果显示:黄、渤海区域颗粒粒径分布斜率在0.46~7.53(均值:4.09),其中84.2%的斜率在3.2~4.5范围内;当参考粒径小于7.33μm时,颗粒粒径分布斜率变化大(均值为5.60±1.09),颗粒粒径分布模拟误差大,平均相对误差绝对值在20%~85%范围内,平均相对误差绝对值的平均值为48.2%;当参考粒径为7.33~19.8μm时,颗粒粒径分布斜率为4.08±0.29,颗粒粒径分布模拟的平均相对误差绝对值在5%~25%范围内,平均相对误差绝对值的平均值为9.8%;当参考粒径大于19.8μm时,颗粒粒径分布斜率为3.87±0.25,颗粒粒径分布模拟的平均相对误差绝对值在2%~10%范围内,平均相对误差绝对值的平均值为6.0%。误差分析表明:参考粒径取值大于19.8μm,幂律模型对颗粒粒径分布的模拟效果较好,最优参考粒径可选为122.0μm,此时模拟误差最小(平均相对误差绝对值的平均值为4.79%±1.78%)。
To accurately describe the distribution of the suspended particle size and achieve a high-precision simulation of the suspended particle size distribution in the Yellow and Bohai Seas, in this study, we examined the applicability of the power law for simulating the particle size distribution(PSD) of suspended particles based on LISST-100 measurements from November 2014. The reference diameter, an important parameter of the power law model, affects the PSD power–law slope and PSD simulation accuracy. We analyzed the influence of different reference diameters on the PSD power–law slope and PSD simulation accuracy. Our results show that most power–law-fitted PSD slopes range from 0.46 to 7.53, and 84.2% of these values are within the range of 3.20 to 4.50(mean: 4.09). Changes in the reference diameter(D0) have a significant influence on the PSD slope and PSD simulation accuracy: when D0 〈7.33 μm, significant changes occur. PSD slopes ranged from 0.46 to 7.53(mean = 5.60, standard deviation = 1.09) and large errors(mean absolute percentage errors(EMAP): 20%–85%, mean EMAP: 48.2%) were observed in PSD slope and PSD simulation, respectively. When 7.33 μm〈 D0 〈19.8 μm, the PSD slope was 4.08 ± 0.0.29 and the PSD simulation error was small(EMAP: 5%—25%, mean EMAP: 9.8%). When D0 〉19.8 μm, the PSD slope was 3.87 ± 0.25, and PSD simulation error was at a minimum(EMAP: 2%—10%, mean EMAP: 6.0%). Through error analysis, we found that for the reference diameter selection greater than 19.8 μm, the PSD simulation results fitted well. We found the optimal reference diameter to be 122.0 μm, at which the simulation error was at a minimum(mean EMAP is 4.79% ± 1.78%).