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王鹏飞 《南京气象学院学报》2002,25(4):539-547
否定了美国格林勒于1980年提出的摄身光影半影原理，阐述了摄身光影能自宝光环中变大漫出的科学原理，并将最常见的摄身光影分为3种类型，还解释了历来观察摄身光影时常提到而未能回答的“各人自见其影”之说，并对此说作了符合实际的修正。 相似文献
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否定了美国格林勒于1980年提出的摄身光影半影原理,阐述了摄身光影能自宝光环中变大漫出的科学原理,并将最常见的摄身光影分为3种类型,还解释了历来观察摄身光影时常提到而未能回答的“各人自见其影”之说,并对此说作了符合实际的修正。 相似文献
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In recent high-resolution observations of complex active regions, long-lasting and well-defined regions of strong flows were
identified in major flares and associated with bright kernels of visible, near-infrared, and X-ray radiation. These flows,
which occurred in the proximity of the magnetic neutral line, significantly contributed to the generation of magnetic shear.
Signatures of these shear flows are strongly curved penumbral filaments, which are almost tangential to sunspot umbrae rather
than exhibiting the typical radial filamentary structure. Solar active region NOAA 10756 was a moderately complex β
δ sunspot group, which provided an opportunity to extend previous studies of such shear flows to quieter settings. We conclude
that shear flows are a common phenomenon in complex active regions and δ spots. However, they are not necessarily a prerequisite condition for flaring. Indeed, in the present observations, the photospheric
shear flows along the magnetic neutral line are not related to any change of the local magnetic shear. We present high-resolution
observations of NOAA 10756 obtained with the 65-cm vacuum reflector at Big Bear Solar Observatory (BBSO). Time series of speckle-reconstructed
white-light images and two-dimensional spectroscopic data were combined to study the temporal evolution of the three-dimensional
vector flow field in the β
δ sunspot group. An hour-long data set of consistent high quality was obtained, which had a cadence of better than 30 seconds
and subarcsecond spatial resolution. 相似文献
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黑臭水体水面阴影对水面光谱信息产生干扰,严重地影响了利用高空间分辨率遥感数据进行水质状况监测的精度,因此,在数据预处理中必须进行阴影剔除。本研究基于无人机高光谱遥感数据,通过分析各种波段组合下黑臭水体水面的阴影像元和水体像元的光谱特征空间,选择以492、666和792 nm处的反射率建立黑臭水体的河面阴影指数（RSSI）,并利用最大类间方差法（OTSU）自动确定划分本影、半影以及水体的阈值。利用南京金川河和龙江河的无人机高光谱遥感影像对算法进行测试,结果表明：RSSI阴影指数能突出显示阴影与水体的差异;OTSU自适应确定的阈值能较好地区分本影、半影和水体,阴影的总体识别精度达到85%以上。该算法能够有效地识别黑臭水体水面阴影,为后续开展水体的定性、定量遥感监测提供数据预处理的技术支持。 相似文献
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