基于瑞利分馏模式的水体蒸发线斜率模型

Slope of evaporation lines in a model based on Rayleigh fractionation formula

瑞利分馏模式是研究水体蒸发同位素变化规律的重要方法。分析了瑞利分馏中分馏系数的影响因子,基于瑞利分馏模式推导了自由水体蒸发线斜率理论方程。分析了湿度和温度因子对于蒸发线斜率的影响。结果表明,在温度不变的情况下,蒸发线斜率随着湿度的增加而减少;在湿度不变的情况下斜率随着温度的升高而增大。利用黄河中游地区的湿度和温度气象因子,基于该斜率模型模拟了黄河中游地区地表水体蒸发线斜率,并进行了实例验证。

The Rayleigh fractionation formula is an important method to study the isotope variation in water bodies un- der the influence of evaporation. The influencing factors on the coefficients of the Rayleigh fractionation formula are analyzed. A model based on the formula is solved for the slope of evaporation lines in water bodies. The influence of humidity and temperature on the slope is analyzed. The result shows that the slope of evaporation lines would reduce with the increase in humidity, and it would become larger with the increase in temperature. Using humidity and tem- perature data, the model is applied and validated on the middle reach region of the Yellow River Basin. The simulated slope of evaporation lines is compared with the surface water isotope data.