海面大气和海洋条件变化引起的太阳辐照度高频变化分析

Analysis for the High-Frequency Variation of the Downwelling Irradiance Caused by Different Atmosphere and Sea Surface Condition

海洋光学考察时需要同步测量大气中的下行太阳辐照度,其测量采样频率比常规大气辐射观测高300倍,可记录到达海面太阳辐射的高频变化。利用2007年在白令海考察的数据,详细研究了辐照度高频变化的特征与原因,得出影响辐照度记录的主要因素有云层、海雾和海浪。结果表明,这3种因素的影响有明显的差别,使作者有可能在不确切知道现场情况的条件下,由数据本身判断辐照度变化的原因,并获取有关的参数。云层引起的辐照度变化具有低频率、大振幅的特征。海雾引起的辐照度变化最为复杂,变化幅度大,变化周期复杂,从几秒到上百秒,与云层效应相区别。晴空条件下,海浪调制的反射信号通过空气中的水汽散射影响辐照度计测量数值,形成周期短、振幅小的稳定振动信号,与云和雾的效应有明显区别。文中提供了云、雾和浪对辐照度影响的定性特征和定量分析结果,对理解海面辐照度记录,并正确处理数据有指导意义。

The downwelling irradiance at the sea surface and some factors are simultaneously measured during the marine optical observation with much higher sampling rate of 0.2 s,which is benefit to study the high-frequency variation in the irradiance record.The data obtained by the authors in Bering Sea of 2007 spring is used to analyze main factors causing the high-frequency variation of the irradiance.The in-fluences of cloud,fog,and sea wave on the irradiance are distinguishable from our data itself.It thus is possible for us to judge and calculate the impact from different factors without detailedin situinforma-tion.The variations of irradiance by the cloud are usually with lower frequency and higher amplitude.Whereas those caused by fog express complex variation with higher amplitude and varying periods from several to a hundred seconds.The complexity is useful to distinguish fog influence from that of cloud.Under the clear sky condition,the steady incident solar radiation is reflected at the sea surface,modulated by the wave oscillation,and then scattered from the particles in the air to the collector of the instrument.So the sea wave signal appears in the irradiance record with short period and low amplitude,clearly differ-ent from the influence of cloud and fog.In this study,the influence of cloud,fog,and wave on irradiance is analyzed and calculated,which is valuable for understanding the irradiance and the corresponding varia-tion in the under water record.