The Study Of The Polarized Characteristics Of Water

More than70%of the earth’s surface area is covered by water, so it is veryimportant to monitor water body for the global environmental research. Aquaticmonitoring by remote sensing has been an effective technology along with thedevelopment of remote sensing technology. The reflection strength of water surface,on the premise of remote sensing, is weaker than other surface features, but it containsmany characteristics of the water body, such as water bubble, oil spill, suspendedsediment and plankton, which can be reflected directly or indirectly, by the opticscharacteristics of the water body.There are many constraints to get real aquatic reflection information in practicaloperations, such as atmospheric effect, variation of the solar incident angles,observing position of detectors, and water status, and atmospheric effect is inevitablein these factors. Because the atmospheric statue varies swiftly, atmospheric reflectiveradiation information usually mask the aquatic information, in both visible spectrumand infrared spectrum. And variation of the solar incident angles, observing positionof detectors and water status make great effect on the aquatic reflection informationreceived by sensors. The most common factor is the solar flare by specular reflection,which makes the information in flares over several tens times stronger than itscounterpart in common range, because sensors are not able to obtain any aquaticinformation in the saturated condition.Aquatic remote sensors are able to obtain real aquatic information, only afteravoiding the reflection direction of the solar vertical incident rays (i.e. surfacedirection). The inverting accuracy to chlorophylls in the water, suspended sedimentswill get great improved, if flares can be eliminated from the total reflection, somulti-angle sensors are able to make aquatic observations from more angles. Ininfrared band, solar flares are still making influence on the water radiation, which ismainly embodied in the specular reflection. In the specular direction, polarized light happens which is caused by aquatic features in both visible and infrared band. Sopolarization technique can make effects in the range that conventional remote sensorcan not achieve. Decomposing reflected lights into different components bypolarization detection technology can make the object polarization degreemeasurement independent from calibrating sensors. So the calculation doesn’t have tostandardize the reflection information.The dissertation, whose theoretical foundation is radiation transfer theory,Fresnel theory and the relationship between Stokes scattering parameters and incidentradiation field, analyzes water surface reflective radiation and emitted radiationpolarization from visible and near infrared to thermal infrared band and the effect ofoil films, atmosphere and water surface flares on polarizations, combining differentdetection angles, incident angles and polarization information. Finally, it, on the basisof Stokes parameters and Fresnel reflection refraction theory, sets up a model forobtaining water reflection information on the calm water surface at different angles bypolarization measurement, and proves the hypothesis is feasible that the polarizationdegree of water-leaving radiance luminance information is zero. The comparisonbetween calculation values and actual measured ones shows that the difference isminor and it’s able to satisfy the measurement precision to water-leaving radiance.The research on water polarization reflection can not only make a more detaileddescription to water radiation and transfer process, but also provide an additionalauxiliary method for water body remote sensing. It can obtain water reflectioninformation in large observation range cooperating with multi-angle sensors withoutavoiding direct sunlight, so that remote sensing technology offers more benefits towater environment monitoring.