Reduction of skylight reflection effects in the above-water measurement of diffuse marine reflectance.
نویسندگان
چکیده
Reflected skylight in above-water measurements of diffuse marine reflectance can be reduced substantially by viewing the surface through an analyzer transmitting the vertically polarized component of incident radiance. For maximum reduction of effects, radiometric measurements should be made at a viewing zenith angle of approximately 45 degrees (near the Brewster angle) and a relative azimuth angle between solar and viewing directions greater than 90 degrees (backscattering), preferably 135 degrees. In this case the residual reflected skylight in the polarized signal exhibits minimum sensitivity to the sea state and can be corrected to within a few 10(-4) in reflectance units. For most oceanic waters the resulting relative error on the diffuse marine reflectance in the blue and green is less than 1%. Since the water body polarizes incident skylight, the measured polarized reflectance differs from the total reflectance. The difference, however, is small for the considered geometry. Measurements made at the Scripps Institution of Oceanography pier in La Jolla, Calif., with a specifically designed scanning polarization radiometer, confirm the theoretical findings and demonstrate the usefulness of polarization radiometry for measuring diffuse marine reflectance.
منابع مشابه
Polarization impacts on the water-leaving radiance retrieval from above-water radiometric measurements.
Above-water measurements of water-leaving radiance are widely used for water-quality monitoring and ocean-color satellite data validation. Reflected skylight in above-water radiometry needs to be accurately estimated prior to derivation of water-leaving radiance. Up-to-date methods to estimate reflection of diffuse skylight on rough sea surfaces are based on radiative transfer simulations and s...
متن کاملRemoval of surface reflection from above-water visible-near infrared spectroscopic measurements.
Water quality estimation in fresh and marine water systems with in situ above-water spectroscopy requires measurement of the volume reflectance (rhov) of water bodies. However, the above-water radiometric measurements include surface reflection (Lr) as a significant component along with volume reflection. The Lr carries no information on water quality, and hence it is considered as a major sour...
متن کاملDIFFUSE REFLECTANCE MEASUREMENTS FROM DIFFERENT SURFACES
Relative diffuse reflection measurements from the original and ground surfaces using a He-Ne laser are reported. The intensity measurements for the metallic, transparent dielectric, matte plastic surfaces and colored papers are presented. Our results indicate that among metallic surfaces tested, aluminum has the highest diffuse reflectance; while the original stainless steel surface shows the l...
متن کاملDevelopment of spacecraft black thermal control coatings using the synthesized mesoporous Co3O4 pigment
The thermo-optical properties of coated surface are important for spacecraft thermal control coatings which depend on the optical properties and structure of the coating material. These coatings control the temperature by their capability of outer energy absorption and its emission. The optical properties of pigment can be improved if the pigment contains a high fraction of voids in its structu...
متن کاملتاثیر عوامل هندسی بر جزر و مد در خورهای طویل
Tidal behavior of esturies is more complicated than open seas. It arises from the effects of geometrical parameters. Also other parameter such as wave reflection from the end of estuaries, sieche, bed friction and coriolis forces cause the water level changes in the esturies to be several times as in the open sea. This paper evalutes the effects of gemetric parameters (such as length, wide and ...
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 38 18 شماره
صفحات -
تاریخ انتشار 1999