Global S&T Development Trend Analysis Platform of Resources and Environment
DOI | 10.5194/acp-17-14353-2017 |
Sky radiance at a coastline and effects of land and ocean reflectivities | |
Kreuter, Axel1,2; Blumthaler, Mario1; Tiefengraber, Martin2,3; Kift, Richard4; Webb, Ann R. | |
2017-12-04 | |
发表期刊 | ATMOSPHERIC CHEMISTRY AND PHYSICS
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ISSN | 1680-7316 |
EISSN | 1680-7324 |
出版年 | 2017 |
卷号 | 17期号:23 |
文章类型 | Article |
语种 | 英语 |
国家 | Austria; England |
英文摘要 | We present a unique case study of the spectral sky radiance distribution above a coastline. Results are shown from a measurement campaign in Italy involving three diode array spectroradiometers which are compared to 3-D model simulations from the Monte Carlo model MYSTIC. On the coast, the surrounding is split into two regions, a diffusely reflecting land surface and a water surface which features a highly anisotropic reflectance function. The reflectivities and hence the resulting radiances are a nontrivial function of solar zenith and azimuth angle and wavelength. We show that for low solar zenith angles (SZAs) around noon, the higher land albedo causes the sky radiance at 20 degrees above the horizon to increase by 50% in the near infrared at 850 nm for viewing directions towards the land with respect to the ocean. Comparing morning and afternoon radiances highlights the effect of the ocean's sun glint at high SZA, which contributes around 10% to the measured radiance ratios. The model simulations generally agree with the measurements to better than 10%. We investigate the individual effects of model input parameters representing land and ocean albedo and aerosols. Different land and ocean bi-directional reflectance functions (BRDFs) do not generally improve the model agreement. However, consideration of the uncertainties in the diurnal variation of aerosol optical depth can explain the remaining discrepancies between measurements and model. We further investigate the anisotropy effect of the ocean BRDF which is featured in the zenith radiances. Again, the uncertainty of the aerosol loading is dominant and obscures the modelled sun glint effect of 7% at 650 nm. Finally, we show that the effect on the zenith radiance is restricted to a few kilometres from the coastline by model simulations along a perpendicular transect and by comparing the radiances at the coast to those measured at a site 15 km inland. Our findings are relevant to, for example, ground-based remote sensing of aerosol characteristics, since a common technique is based on sky radiance measurements along the solar almucantar. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000416941000003 |
WOS关键词 | RADIATIVE-TRANSFER ; OPTICAL-PROPERTIES ; SOFTWARE PACKAGE ; MODEL ; IRRADIANCE ; ATMOSPHERE ; ALBEDO ; SUN |
WOS类目 | Environmental Sciences ; Meteorology & Atmospheric Sciences |
WOS研究方向 | Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/30706 |
专题 | 地球科学 |
作者单位 | 1.Med Univ Innsbruck, Div Biomed Phys, Innsbruck, Austria; 2.Earth Observat Technol, LuftBlick, Mutters, Austria; 3.Univ Innsbruck, Inst Atmospher & Cryospher Sci, Innsbruck, Austria; 4.Univ Manchester, Sch Earth Atmospher & Environm Sci, Manchester, Lancs, England |
推荐引用方式 GB/T 7714 | Kreuter, Axel,Blumthaler, Mario,Tiefengraber, Martin,et al. Sky radiance at a coastline and effects of land and ocean reflectivities[J]. ATMOSPHERIC CHEMISTRY AND PHYSICS,2017,17(23). |
APA | Kreuter, Axel,Blumthaler, Mario,Tiefengraber, Martin,Kift, Richard,&Webb, Ann R..(2017).Sky radiance at a coastline and effects of land and ocean reflectivities.ATMOSPHERIC CHEMISTRY AND PHYSICS,17(23). |
MLA | Kreuter, Axel,et al."Sky radiance at a coastline and effects of land and ocean reflectivities".ATMOSPHERIC CHEMISTRY AND PHYSICS 17.23(2017). |
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