| DOI: | 10.1002/jgrd.50182
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| 论文题名: | Optical power and energy radiated by natural lightning |
| 作者: | Quick M.G.; Krider E.P.
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| 刊名: | Journal of Geophysical Research Atmospheres
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| ISSN: | 21698996
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| 出版年: | 2013
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| 卷: | 118, 期:4 | | 起始页码: | 1868
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| 结束页码: | 1879
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| 语种: | 英语
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| 英文关键词: | lightning
; optical
; radiation
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| Scopus关键词: | Electromagnetism
; Heat radiation
; Infrared radiation
; Light extinction
; Lightning
; Atmospheric extinction
; Central Great Plains
; Cloud-to-ground lightning
; Electromagnetic power
; Intracloud discharge
; optical
; Satellite measurements
; Visible and near infrared
; Clouds
; calibration
; electromagnetic radiation
; estimation method
; lightning
; near infrared
; optical property
; radiation balance
; satellite imagery
; Portulaca sclerocarpa
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| 英文摘要: | Calibrated measurements of the visible and near-infrared radiation produced by both negative and positive cloud-to-ground (CG) lightning strokes have been made at distances of 5 to 32 km in southern Arizona (AZ) and the central Great Plains using a photodiode sensor with a flat spectral response between 0.4 and 1.0 μm. Time-correlated video images (60 fps) of the channel development provided information about the types of strokes that were detected and reports from the U.S. National Lightning Detection Network indicated their locations, polarities, and estimates of their peak current. In our sample of negative strokes that were suitable for analysis, there were 23 first (or only) strokes (FS), 19 subsequent strokes that created new ground contacts (NGC), and 101 subsequent strokes that re-illuminated a preexisting channel (PEC). We also analyzed 10 positive strokes (in nine flashes), and 73 of the larger impulses that were radiated by intracloud discharges (CPs). Assuming that these events can be approximated as isotropic sources and that the effects of atmospheric extinction are negligible, the peak optical power (Po), total optical energy (Eo), and characteristic widths of the sources (t cw = Eo/Po) have been computed. Median values of Po for negative FS, NGC, and PEC strokes were 1.8 × 10 10 W, 1.1 × 1010 W, and 4.4 × 109 W, respectively. Median values of Eo were 3.6 × 106 J, 3.5 × 106 J, and 1.2 × 106 J, respectively. The median characteristic widths of negative FS, NGC, and PEC strokes were 229 μs, 244 μs, and 283 μs, respectively. Positive CG strokes produced a median Po, Eo, and tcw of 1.9 × 10 10 W, 9.3 × 106 J, and 497 μs, respectively. Estimates of the space-and-time-average power per unit length (ℓo) in the lower portion of negative FS, NGC, and PEC channels had medians of 2.8 × 106 W/m, 3.2 × 106 W/m, and 1.4 × 10 6 W/m, respectively, and the median ℓo for four positive strokes was 8.8 × 106 W/m. Median values for the estimated peak electromagnetic power (PEM) radiated at early times in the strokes are 2.0 × 109 W, 2.5 × 109 W, 1.0 × 109 W, and 9.1 × 109 W for FS, NGC, PEC and positive strokes, respectively. CP events produced a median Po, E o, and tcw of 2.0 × 109 W, 0.7 × 106 J, and 311 μs, respectively, and are in good agreement with aircraft and satellite measurements. The values of Po, Eo, and ℓo for negative CG strokes in AZ are significantly larger than prior measurements in Florida, likely because there is less atmospheric extinction in our dataset, and due to extinction, all the above values of Po, Eo, and ℓo are lower limits at the source. Key PointsGives absolute optical power and energy produced by lightningCompares different types of CG strokesPeak optical and electromagnetic powers are of comparable magnitude © 2013. American Geophysical Union. All Rights Reserved. |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/63909
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| Appears in Collections: | 影响、适应和脆弱性
气候减缓与适应
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作者单位: | Institute of Atmospheric Physics, University of Arizona, Physics-Atmospheric Sciences Bldg, 1118 E 4th St, Tucson, AZ 85721-0081, United States
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| Recommended Citation: | |
Quick M.G.,Krider E.P.. Optical power and energy radiated by natural lightning[J]. Journal of Geophysical Research Atmospheres,2013-01-01,118(4)
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