Jäkel Evelyn, Wendisch Manfred, Kniffka Anke, Trautmann Thomas
Leibniz-Institute for Tropospheric Research, Permoserstrasse 15, D-04318 Leipzig, Germany.
Appl Opt. 2005 Jan 20;44(3):434-44. doi: 10.1364/ao.44.000434.
An airborne system for fast measurements of spectral actinic flux densities in the wavelength range 305-700 nm is introduced. The system is called the Actinic Flux Density Meter (AFDM). The AFDM utilizes the diode array technique and measures downwelling and upwelling spectral actinic flux densities separately with a time resolution of less than 1 s. For airborne measurements this means a spatial resolution of approximately 60 m, assuming an average aircraft velocity of 60 m/s. Thus the AFDM resolves fast changes in the actinic radiation field, which are of special importance for conditions of inhomogeneous clouds or surface reflection. Laboratory characterization measurements of the AFDM are presented, and a method to correct the nonideal angular response of the optical inlets is introduced. Furthermore, exemplar field data sampled simultaneously with spectral irradiance measurements are shown. The horizontal variability of the measured spectra of actinic flux density is quantified, and profile measurements for overcast situations are presented. Finally, the effects of clouds on the spectral actinic flux density are discussed.
介绍了一种用于快速测量波长范围在305 - 700 nm光谱光化通量密度的机载系统。该系统称为光化通量密度计（AFDM）。AFDM采用二极管阵列技术，以小于1 s的时间分辨率分别测量下行和上行光谱光化通量密度。对于机载测量，假设飞机平均速度为60 m/s，这意味着空间分辨率约为60 m。因此，AFDM能够分辨光化辐射场的快速变化，这对于不均匀云层或表面反射的情况尤为重要。给出了AFDM的实验室特性测量结果，并介绍了一种校正光学入口非理想角度响应的方法。此外，还展示了与光谱辐照度测量同时采样的典型现场数据。对测量的光化通量密度光谱的水平变化进行了量化，并给出了阴天情况下的剖面测量结果。最后，讨论了云层对光谱光化通量密度的影响。
