3.7 x 1013 cm-3, 3 x 109 cm-3, and 7.5 x 1012 cm-3, respectively, at the lower boundary, and that of O3 is fixed at 6 x 10" cm-3 in order to conform to measured values. To assess the influence of ozone on the temperature structure (and thus the chemical composition) of the upper stratosphere and lower mesosphere, we have included a heating and cooling code, which is not described in our earlier papers. The heating algorithm is developed from the work of Lacis and Hansen (21). Their method, a parametric treatment based on accurate multiple-scattering computations, includes the effects of Earth's albedo. (The planetary albedo is assumed to be constant and equal to 0.34; see Ref. 22, p. 2-2.) The vertical distributions of ozone both above and below the calculation point are accounted for in the calculation of the absorbed and scattered solar radiation. Because the heating rate is dependent on the zenith angle and on the number of hours of daylight, diumally averaged heating rates are calculated, as described by Cogley and Borucki (11). The heating rates are calculated at each latitude and altitude every 7 days so that the changing solar position and number of hours of daylight are taken into account. The cooling rates are computed from a Newtonian cooling model (23) such that where R is the cooling rate (in degrees per day), AT is the model-calculated temperature minus the standard atmosphere reference temperature, and A(0,P) and B(P) are latitude-dependent (0) and pressure-dependent (P) parameters. The were determined by requiring the radiative cooling to exactly balance the radiative heating for the standard reference temperature (AT = 0) and ozone profiles. The B(P) were taken from the work of Dickinson (23). In Fig. 3, 2-D-model predictions for the ambient atmosphere (autumn, latitude 40 °N) are shown. The agreement with observational data is about the same as that obtained with the 1-D model, except for NO; the mesospheric concentrations appear to be about an order of magnitude too small between 55 and 85 km (34-53 mi). We attribute the low predicted values to the absence of a mesospheric source of NO |see processes (6)] in the model and to slow upward transport of NO from the stratosphere; the vertical eddy diffusivity in the mesosphere is probably a factor of 2 to 3 too low, a state of affairs that is not readily correctable because of limitations in calcula- tional stability. To complement our one-dimensional and two-dimensional analyses of the widespread photochemical effects caused by rocket emissions, we utilize a simple model of an expanding rocket plume to study potentially important local effects of the rocket plume. The model is applied for both rocket launch and reentry events, and is predicted on several approximations. The simulated launch-reentry plume is oriented vertically and has cylindrical symmetry. The 1-D model is used to sample the entire plume, although the plume may be truncated in altitude extent to simulate a flight trajectory. The plume is given an initial width corresponding to a short period of expansion. The rocket ejecta at each height are averaged over the initial area of the trail, and these concentrations, when added to the ambient concentrations, represent the starting conditions for the calculations. The area of the rocket trail is assumed to increase with time according to the relation (24) where A is the area (cm2), K is the effective horizontal diffusion coefficient (cm2
RkJQdWJsaXNoZXIy MTU5NjU0Mg==