| 太阳直接辐射光量子通量的气候学计算方法 |
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| 引用本文： | 周允华,项月琴.太阳直接辐射光量子通量的气候学计算方法[J].地理学报,1987(2). |
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| 作者姓名： | 周允华 项月琴 |
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| 作者单位： | 中国科学院地理研究所农业生态系统试验站
(周允华)，中国科学院地理研究所农业生态系统试验站(项月琴) |
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| 摘 要： | 为了把太阳直接辐射通量密度换算成光量子通量密度,取用了一个简单的大气模式,计算了各种太阳高度、地面气压和大气浑浊度下太阳直接辐射中的光合有效辐射能量通量和光量子通量,从而得到了单位光合有效辐射能量所具有的光量子数。结果表明:这个数是比较稳定的。在平原地区,10—90°的太阳高度范围内,1W.m~(-2)的光合有效辐射通量密度具有4.72±0.11μmol.m~(-2).s~(-1)的光量子通量密度。本文还采用北京地区四个季节定时的太阳直接辐射分光测量资料和高原观测资料检验了模式计算结果的可靠性,获得了满意的结果。
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| 关 键 词： | 光合有效辐射 量子通量密度 简化的大气模式 大气浑浊度太阳光谱辐照度 太阳直接辐射 |
THE CLIMATIC ESTIMATION OF PHOTON FLUX DENSITY OF DIRECT SOLAR RADIATION |
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| Zhou Yunhua Xiang Yueqin.THE CLIMATIC ESTIMATION OF PHOTON FLUX DENSITY OF DIRECT SOLAR RADIATION[J].Acta Geographica Sinica,1987(2). |
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| Authors: | Zhou Yunhua Xiang Yueqin |
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| Abstract: | (1) Based on the transfer equation of direct solar radiation in the atmosphere a formula of estimating the amount of photons, n, corresponding to one unit of PAR (0.4-0.7 u,) of the direct solar radiation at sea level has been developed, i.g.
where U is the photon flux density, SPAR is the fux density of PAR. N is Avogadro number, k is the planck's constant, c is the velocity of light speed. X is the wave length. So is the spectral irradiance at the top of the atmosphere. P ,a and P,o3 are the spectral transmittances of air moleoules and the ozone, respectively, at the sea level, m and m* are the absolute and relatilve air masses, respectively. 8 is the Angstrom atmospheric tubidity coefficient, a is the wave length index.
Based on the information 14-15] the relationship between a and |3 has been derived (Fig. 1)
Using equation (I) the photon flux densities n were calculated at the air pressures of 1000 hP?and 700 hPa and at the Angstrom atmospheric tubidity coefficients, |3 of 0.02, 0.04, 0.10, 0.15, 0.20, 0.30 and 0.40, It showed that at sea level (1000 hP.) ?= 4.72?.11 umol ?J-1 PAR and at the height which is equvalent to 700 hPa,n= 4.64?.06 umol- J-1 PAR.
(2) Based on the measured spectral irradiance of direct solar radiation in six subdivisions of the PAR wave band in Beijing during the four seasons 1977-1978. That is n = 4.71?.05 umol-J-1 PAR, which is almost the same as the ones from the model calculation.
(3) The values of n at the various solar elevations h were calculated based on the measurements in Beijing and the information 17] in Changdu and Lhasa (3200?600 m in the heights) on the Xizang Plateau. The comparision of the esults from the measured data with the ones from the model calculation showed that both of the values of n were very similar at the solar elevations of h>50? i.g.n = 4.65 umol' J-1 PAR at sea level and n= 4.60 umol-J-1 PAR in Xizang Plateau. But in the case of solar elevation of A<50?the values of n which were calculated from the measured data were slightly smaller than the ones from the model calculation. |
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| Keywords: | : Photosynthetically active radiation Quantum flux density Simple atmospheric model Atmospheric tubidity Solar spectral irradiance Direct solar radiation |
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