海-气CO2通量实测数据通量计算中误差传递模拟与敏感性分析

海-气CO₂通量估算模型中参数的可靠性是决定模型可靠性的重要因素, 也决定了模型估算结果的可靠性, 因此开展海-气CO₂通量计算模型中误差传递规律与敏感性分析, 对模型参数端元因子的误差控制, 提高模型预测精度和降低不确定性十分重要。但由于模型中参数众多, 且各种参数间彼此相互影响, 使得误差传递过程与敏感性分析十分复杂困难。本文在海-气界面CO₂通量观测建模过程详细分析的基础上, 以海-气界面CO₂分压差的经典通量计算模型为基础, 以实测数据通量计算过程为例, 针对模型中的参数变量, 在假设参数变量的误差正态分布的前提下, 利用Monte Carlo手段分析各参数变量的误差在模型中的传递规律, 并将单因子扰动试验法用于海-气界面CO₂通量建模的参数敏感性分析。模拟和分析结果表明:CO₂通量计算过程中误差经模型传递后的分布规律存在正态分布、指数分布等多种形式;气体交换系数对通量计算结果的敏感性最大, 通量估算中的风速和表层海水温度是必须进行精度控制的关键参数。

Error propagation simulation and sensitivity analysis for air-sea CO2 fluxes calculate by measured data

The reliability of air-sea CO₂ fluxes estimation model parameters is an important factor in determining the reliability of the model and also determines the reliability of the model estimation results, so it is important to carry out the sea-air CO₂ fluxes estimation model error propagation law and sensitivity analysis for controlling the endmember factors of the model parameters, improving the model prediction accuracy and reducing the uncertainty. Since there are many parameters in the model, and various parameters influence each other, it is difficult to analyze error propagation process and sensitivity analysis. In this paper, based on the detailed analysis of air-sea CO₂ fluxes estimation model establishment process and the classic computation model of the air-sea CO₂ fluxes 2 partial pressure difference, taking the in situ data fluxes model establishment as an example, in term of the parameters in the model, assuming the normal distribution of the parameter error, the error propagation law of each parameter in the model was analyzed using the Monte Carlo technique, and the single-factor perturbation test method was used for the air-sea CO₂ fluxes estimation model parameters sensitivity analysis. It was shown from the simulation and analytical results: CO₂ flux measurement model error propagation law meet various forms, such as the normal distribution and exponential distribution; gas exchange coefficient is sensitive to the flux calculation results, and the wind speed and sea surface temperature accuracy are the critical parameters to be concerned and controlled in the process of the flux estimation.