Diagnosis of dynamics and energy balance in the mesosphere and lower thermosphere

A diagnostic technique has been developed to consistently derive all the dy namical and chemical tracer fields based on one or a few well-measured fiel ds such as temperature and ozone distributions. The technique is based on t he new Johns Hopkins University/Applied Physics Laboratory (JHU/APL) global ly balanced 2D diagnostic model that couples the dynamics with photochemist ry. This model is especially useful for studying the mesosphere and lower t hermosphere where dynamics, radiation, and photochemistry strongly interact . The novelty of the diagnostic model is to derive the wave drag and eddy d iffusion coefficient directly from the better-defined thermal forcing with its major contributions derived from the zonal mean components. The latter is also affected by the advective and diffusive transports. The derived tra cer distributions together with input field(s) provide the necessary radiat ive and chemical heating rates for the calculation of the thermal forcing. Two numerical experiments with different input fields are conducted with th e JHU/APL 2D diagnostic model. Using the COSPAR International Reference Atm osphere 1986 model atmosphere as the input temperature field, the first exp eriment produces a meridional velocity of similar to 10 m s(-1) and a peak ozone mixing ratio of similar to2 ppmv near the mesopause. The second exper iment incorporates additional ozone information obtained from the High Reso lution Doppler Imager (HRDI) measurements as part of the input fields. Mont hly zonal mean HRDI ozone (similar to4-8 ppmv near the mesopause) is merged with the lower values of model climatology using statistical scaling. In t his second experiment, the diagnostic model produces the enhancements in ra diative and chemical heating, wave drag, residual circulation, and eddy dif fusion coefficient that are necessary to maintain the high input ozone conc entration near the mesopause.