Reduction of radiometric miscalibration--applications to pushbroom sensors.

The analysis of hyperspectral images is an important task in Remote Sensing. Foregoing radiometric calibration results in the assignment of incident electromagnetic radiation to digital numbers and reduces the striping caused by slightly different responses of the pixel detectors. However, due to uncertainties in the calibration some striping remains. This publication presents a new reduction framework that efficiently reduces linear and nonlinear miscalibrations by an image-driven, radiometric recalibration and rescaling. The proposed framework-Reduction Of Miscalibration Effects (ROME)-considering spectral and spatial probability distributions, is constrained by specific minimisation and maximisation principles and incorporates image processing techniques such as Minkowski metrics and convolution. To objectively evaluate the performance of the new approach, the technique was applied to a variety of commonly used image examples and to one simulated and miscalibrated EnMAP (Environmental Mapping and Analysis Program) scene. Other examples consist of miscalibrated AISA/Eagle VNIR (Visible and Near Infrared) and Hawk SWIR (Short Wave Infrared) scenes of rural areas of the region Fichtwald in Germany and Hyperion scenes of the Jalal-Abad district in Southern Kyrgyzstan. Recovery rates of approximately 97% for linear and approximately 94% for nonlinear miscalibrated data were achieved, clearly demonstrating the benefits of the new approach and its potential for broad applicability to miscalibrated pushbroom sensor data.

Reproductive cycle of northern largemouth bass Micropterus salmoides salmoides.

The seasonal dynamics of the northern largemouth bass (Micropterus salmoides salmoides) reproductive cycle was investigated in a Midwestern United States population. Mature largemouth bass (n = five males and five females) were collected each month over a one-year period. Environmental cues (water temperature and photoperiod) were recorded in situ using data loggers. Temporal changes in plasma sex steroid hormones (testosterone [T], 11-ketotestosterone [11-KT], and estradiol-17ß [E2 ]) and vitellogenin (Vtg), gamete development (histology), and organosomatic indices were highly associated with temporal water temperature and photoperiod dynamics. Female plasma concentrations of T and E2 and organosomatic indices exhibited similar temporal patterns, with peaks occurring in early summer. Gamete development in females was associated with increases in gonadosomatic index (GSI) and Vtg. In males, plasma concentrations of T and organosomatic indices exhibited bimodal peaks; high peaks occurred in the spring for T and GSI and in the fall for viscerosomatic and hepatosomatic indices. Male gamete development and GSI closely tracked temporal patterns in plasma T, with GSI lagging behind the T cycle by approximately one sampling period. Plasma concentrations of 11-KT were elevated in late winter and spring and were considerably higher than T throughout the reproductive cycle. Unlike the Florida largemouth bass (M. salmoides floridanus) advanced gamete development was observed in both sexes before winter, which may reduce the immediate energy required for gamete development in the spring. Results from this study also provide baseline information necessary for off-season spawning procedures and endocrine-disruption studies in northern largemouth bass.