Sources of variance of downwelling irradiance in water.
نویسندگان
چکیده
The downwelling irradiance in water is highly variable due to the focusing and defocusing of sunlight and skylight by the wave-modulated water surface. While the time scales and intensity variations caused by wave focusing are well studied, little is known about the induced spectral variability. Also, the impact of variations of sensor depth and inclination during the measurement on spectral irradiance has not been studied much. We have developed a model that relates the variance of spectral irradiance to the relevant parameters of the environmental and experimental conditions. A dataset from three German lakes was used to validate the model and to study the importance of each effect as a function of depth for the range of 0 to 5 m.
منابع مشابه
Wave-induced light field fluctuations in measured irradiance depth profiles: A wavelet analysis
Rapid variations in the intensities of light are commonly observed in profiles of downwelling plane irradiance in the ocean. These fluctuations are often treated as noise and filtered out. Here an effort is made to extract the pertinent statistics to quantify the light field fluctuations from vertical profiles of irradiance measured under clear skies. The irradiance data are collected in oceani...
متن کاملMonte Carlo radiative transfer simulation for the near-ocean-surface high-resolution downwelling irradiance statistics
We present a numerical study of the near-surface underwater solar light statistics using the state-ofthe-art Monte Carlo radiative transfer (RT) simulations in the coupled atmosphere-ocean system. Advanced variance-reduction techniques and full program parallelization are utilized so that the model is able to simulate the light field fluctuations with high spatial [Oð10−3 mmÞ] and temporal [Oð1...
متن کاملCDOM retrieval using measurements of downwelling irradiance [8888-17]
As it can strongly influence the availability of light and thus primary production, coloured dissolved organic matter (CDOM) affects the function of lake ecosystems. Therefore reliable methods are required for the monitoring of CDOM concentration. A new method using downwelling irradiance was tested for applicability in four selected lakes of the Bavarian Osterseen Lake District, which consists...
متن کاملAnalytic model for the direct and diffuse components of downwelling spectral irradiance in water.
The direct and diffuse components of downwelling irradiance have in general different path lengths in water, and hence they decrease differently with sensor depth. Furthermore, the ever-changing geometry of a wind-roughened and wave-modulated water surface induces uncorrelated intensity changes to these components. To cope with both effects, an analytic model of the downwelling irradiance in wa...
متن کاملOn the Parameterization of Irradiance for Open Ocean Photoprocesses
Measurements of downwelling spectral irradiance were made during the fall of 1982 in the North Pacific Ocean (near 33øN, 142øW). These data are used to produce vertical profiles of downwelling irradiance for visible energy (400-700 nm) and photosynthetic available radiation (PAR). The profiles demonstrate that the attenuation of visible energy and PAR are primarily functions of chlorophyll pigm...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Applied optics
دوره 50 15 شماره
صفحات -
تاریخ انتشار 2011