通用大气辐射传输软件CART在场景计算中的应用(特邀)

Applications of scene calculations of atmopsheric radiative transfer by using of CART(Invited)

研制了通用大气辐射传输软件CART,可以根据大气参数计算可见光到远红外波段的大气光谱透过率和背景辐射(包括环境散射太阳辐射和热辐射)。光学工程特别关注某一波段的大气透过率随天顶角、距离等参数的多维变化,需要快速计算这些场景变化的大气光学特性。介绍了CART新增的大气辐射传输二维场景计算功能。引入离散坐标法(DISORT)模块,一次计算可同时得到各方位角和天顶角的多次散射辐射强度,大大提高了计算效率。对于大气透过率和热辐射随空间位置的变化缓慢的特点,采用抽样计算、样条插值的方法,在保持计算精度基本不变的情况下,大大节省了计算时间。对于场景计算,相对于逐点串行计算,速度提高了2~3个量级。这在实际工程应用的大气辐射传输场景计算中将有重要的应用。

A Combined Atmospheric Radiation Transfer(CART)software was developed,which could be used to calculate the spectral transmittance and background radiation(including ambient scattered solar radiation and thermal radiation)of the atmosphere from visible to far infrared wavelength bands based on atmospheric parameters.The multi-dimensional variations of atmospheric transmittance and background radiation in a certain wavelength-band with zenith angle and distance were paid special attention by researches in optical engineering area.Thus,it was necessary to quickly calculate the scene atmospheric optical characteristics.The newly twodimensional scene fast computing function of atmospheric radiative transfer by using CART was mainly introduced.According to the characteristics of discrete coordinate method(DISORT)which could simutaniously output the radiance at various zenith angles and azimuth angles,the program to calculate the multiple-scattered atmospheric radiance was designed at each direction(azimuth and zenith angles)simultaneously,which greatly improved the calculation efficiency.As the atmospheric transmittance and heat radiation change slowly with space position,sampling calculation and spline interpolation were adopted to save the calculation time greatly while keeping the calculation accuracy.For a scene with more than 10000 times calculations,the speed was 2-3 orders of magnitude faster than before.It will be usefull in the calculation of atmospheric radiative transfer scenarios in practical engineering applications.