Ground reflectance measurement techniques: a comparison.
The relative accuracies of reflectance factor measurement methods involving the simultaneous, as compared to the sequential, measurement of irradiance on and radiance reflected from the target are discussed. Data are presented to support a statistical demonstration that the simultaneous measurement technique is the more accurate.
Factors controlling the manual and automated extraction of image information using imaging polarimetry
The factors governing the extraction of useful information from polarimetric images depend upon the image acquisition and analytical methodologies being used, and upon systematic and environmental variations present during the acquisition process. The acquisition process generally occurs with foreknowledge of the analysis to be used. Broadly, interactive image analysis and automated image analysis are two different procedures: in each case, there are technical challenges. Imaging polarimetry is more complex than other imaging methodologies, and produces an increased dimensionality. However, there are several potential broad areas of interactive (manual) and automated remote sensing in which imaging polarimetry can provide useful additional information. A review is presented of the factors controlling feature discrimination, of metrics that are used, and of some proposed directions for future research.
Frequency distributions of the mixing height over an urban area from SODAR data
The height of the mixing-layer (MLH) is an important parameter in the assessment of the dilution of primarily emitted or secondarily formed air pollutants in the atmospheric boundary-layer. A continuous measurement of MLH is possible only by remote sensing. Here, 17 months of SODAR data have been analysed automatically to derive the MLH over the city of Hannover in Northern Germany. In contrast to earlier studies the MLH has been determined from vertical profiles of the acoustic backscatter intensity and from the variance of the vertical velocity component. The results are presented in form of monthly frequency distributions and mean daily courses of MLH. These statistical evaluations of MLH show a clear annual course and interannual variability. The study shows the possibility to derive meaningful climatological information from long-term SODAR measurements for air quality issues.