A MODEL STUDY OF THE TEMPORAL BEHAVIOR OF THE EMISSION INTENSITY AND ROTATIONAL TEMPERATURE OF THE OH MEINEL BANDS FOR HIGH-LATITUDE SUMMERCONDITIONS

The temporal variation of OH emission and weighted rotational tempera ture has been studied for high-latitude summer conditions. Observation s for 60 degrees N latitude show OH weighted temperatures that always exceed 145 K even during periods of noctilucent clouds. Using a one-di mensional model the effects in excited OH concentration produced by ch anges in temperature, eddy diffusion, and water concentration have bee n analysed. We are forced to conclude that there remains a discrepancy between the OH temperatures predicted by the model and that obtained from OH measurements. An increase in OH* concentration from June to t he beginning of August, followed by a slow decrease during August has been obtained in agreement with the measurements. The 16-day modulatio n present in the measurements was simulated in a simple manner by vary ing the temperature in the mesopause region. This variation produces p eriodic modulations in both OH concentration and weighted temperature of 16 days. The results show the temperature leading the OH column c oncentration by three days. This phase shift is also present in the ob servations.