THE IMPACT OF NON-LAMBERTIAN WAVELENGTH-DEPENDENT REFLECTING SURFACESON STRATOSPHERIC RADIATION AND PHOTOCHEMISTRY

We have developed models of physically-based cloud and ocean surfaces for use in photochemical models. These surface models are described in terms of a flux albedo and a normalized reflection function. Through these, the dependence of albedo on wavelength, solar zenith angle, clo ud optical depth (cloud surfaces) and surface windspeed (ocean surface s) are allowed for. In addition, the non-Lambertian nature of these su rfaces is accounted for. We have integrated these surface models into a multiple scattering radiative transfer model to assess their effects on the stratospheric radiation field and J-values. This was accomplis hed by comparison with results obtained using Lambertian, constant alb edo surfaces. Comparisons of stratospheric radiation fields revealed t hat both the wavelength and directional dependences of the cloud and o cean surfaces could be large effects. Differences between calculated J -values varied from 0 to 12% depending upon species, solar zenith angl e, and height. ?The J-values were then used as input for a chemical bo x model to examine the effects these surfaces had on stratospheric che mistry. Comparisons were made against box model runs using J-values fr om constant surfaces. Overall, the effect was on the order of 10%. Dif ferences in number densities using these different surfaces varied wit h latitude, height and species. Runs were made with and without hetero geneous chemistry.