基于TUV模式的银川光化辐射通量特征及其影响因子

Analysis of actinic flux and its influence factors in Yinchuan based on TUV model

利用TUV模式计算分析了银川光化辐射通量变化特征,探讨了云、气溶胶、臭氧柱浓度、NO_(2)柱浓度等因子对银川光化辐射通量的影响。结果表明:2019年7—9月银川月平均光化辐射通量分别为6.5E+16光子数·cm^(-2)·s^(-1)、5.6E+16光子数·cm^(-2)·s^(-1)和4.7E+16光子数·cm^(-2)·s^(-1),日最大值出现在13:00;波长小于325 nm时,光化辐射通量随波长增加缓慢上升,波长在325—480 nm之间时,光化辐射通量迅速升高,波长大于480 nm时,光化辐射通量随波长增加变化较小,此特征在中午前后较早晚表现更明显;云光学厚度和气溶胶光学厚度对光化辐射通量的衰减作用具有明显的“U”型日变化特征,比较而言,气溶胶光学厚度对光化辐射通量衰减作用的“U”型波形更为宽广;光化辐射通量衰减率对较低的云光学厚度的变化更敏感;光化辐射通量随气溶胶光学厚度增加而减小的变率要比随云光学厚度增加而减小的变率小;光化辐射通量对单次散射反照比大于0.6的强散射性气溶胶的变化更敏感,且气溶胶光学厚度越大,此特性整体表现越明显;波长指数对光化辐射通量的影响相对较小。

Based on the TUV(tropospheric ultraviolet-visible radiation)model,the variation characteristics of actinic flux in Yinchuan were calculated and analyzed,and the influence of cloud,aerosol,column concentration of ozone,and NO_(2) on actinic flux was further discussed.The results show that the monthly average actinic flux of Yinchuan from July to September of 2019 was 6.5E+16 quanta·cm^(-2)·s^(-1),5.6E+16 quanta·cm^(-2)·s^(-1),and 4.7E+16 quanta·cm^(-2)·s^(-1),respectively,with daily maximum appearing at 13:00.The actinic flux rises slowly with the increase of wavelength when the wavelength is less than 325 nm,and it rises rapidly when the wavelength is between 325 nm and 480 nm,whereas it changes slightly with the increase of wavelength when the wavelength is above 480 nm.The variations appear more significantly around noon than in the morning and evening.The attenuation effects of cloud optical thickness and aerosol optical depth on actinic flux have obvious“U”-shaped diurnal characteristics.Comparatively speaking,the“U”-shaped waveform of the attenuation effect of aerosol optical thickness on actinic flux is wider than that of aerosol optical thickness.The decay rate of actinic flux is more sensitive to the changes in lower cloud optical thickness.The variability of actinic flux decreasing with the increase of aerosol optical depth is smaller than that with the increase of cloud optical thickness.Actinic flux is more sensitive to the change of strong scattering aerosol with single scattering albedo greater than 0.6,and the larger the aerosol optical thickness is,the more obvious this characteristic is.The influence of wavelength exponent on actinic flux is relatively small.