Radiative Transfer Parameterizations And Reconstruction Of Driving Forces In Climate Change

Issues related climate chang have been a significant scientific problem, which has beenconcered by scienctst all over the word. In the paper, two physical issues (radiative transferparatermeziaon and reconstruction of driving forces) closely realted the climate changes isstudied. For transfer paratermeziaon, we develop delta-four-stream adding/doubing theory,and eventually propose efficient and accurate four-stream discrete ordinates adding/doubingmethod (δ-4DDA) and delta-four-stream spherical harmonic expansion adding/doubingmethod(δ-4SDA).In addition, we examine the accuracy and efficiency of the δ-4DDA andδ-4SDA.It is shown that δ-4DDA is slightly more accurate than δ-4SDA in heating rates andδ-4SDA is superior to δ-4DDA in computational efficiency. In generall, both of δ-4DDA andδ-4SDA is suitable for application in climate models. Then, it is found that the solution ofdiffuse radiation is a special case of the solution for direct radiation. No extra effort is neededto find out the solution of diffuse radiation. This kind of relation can be applied to calculatethe snow albedo, as the diffuse albedo can be obtained from the direct albedo withoutinvolving the angular integral. For reconstruction of driving forces, based on the calculationof cross-prediation errors, we propose several methods to reconstruct the external forcingfrom nonlinear nonstationary time series including stationary regions; Secondly, the theexternal forcing of Lorenz system is reconstructed inversion, which generalizes the application of the cross-prediction methods; and then an unkown driving force isreconstructed in the system controlled by two driving forces. What’s more, the driving forceof northern hemisphere climate system is retrieved from the time series of northernhemisphere surface air temperature. In addition, wavelet analysis is used to identify anddescribe variability of the driving forces. There are four different periods for driving forces ofNorthern Hemisphere temperatures in the last hundred years:55years (S1),20years (S2) and9years (S3).10-11years and71-78years are the fundamental wave.18-19years and32-35years are the two harmonics of the fundamental wave.