声雷达定量测量C_T~2中的几个问题

本文讨论了逾量衰减和风对声线的弯曲作用对声雷达接收功率的影响.分析和计算表明在很多情况下分子吸收、逾量衰减和风的影响对测量C_T~2是不能忽略的,不考虑这些因素有时可使C_T~2低估500％以上.引进有效湍流外尺度后使声散射截面表达式在实际应用中变得合理而简单.由简化的几何模型导出了风衰减因子,经计算和以往的实验事实相符.因此在原声雷达方程中应加入风衰减因子.声雷达方程加上逾量衰减算式、风衰减算式和分子衰减算式,组成了适合定量测量C_T~2的声雷达方程组.利用温度脉动仪测定低高度上的C_T~2值可使估算工作简化,此方法在多普勒声雷达上应用效果会较好,本文并给出了初步实验结果.

On the measurement of CT2 by sodar

After introducing the effective turbulent outer scale for excess attenuation estimation, the divergence of integral and the perplexity of applying the scatter section to the excess attenuation estimation have been avoided. According to an analysis, the excess attenuation for back scattering waves is stronger than that for the transmissive waves . A simplified formula for estimating the effect of wind refraction is also presented . CT2 may be underestimated by about 5% to 500% or more without considering these two factors. The modified sodar equations including these two factors and molecular absorption are constructed . It is possible to measure CT2 profiles with Doppler sodar and a platinum resistance thermometer without the calibration of sodar parameters . The results of primary experiments are presented .