Impact of diurnal variability on UARS synoptic products

We examine the impact of diurnal variability on the synoptic behavior of oz one observed by the Upper Atmosphere Research Satellite (UARS). Synoptic pr oducts generated via Kalman filtering are compared against those recovered via Fast Fourier Synoptic Mapping (FFSM). In FFSM products, tracer anomalie s defining distinct air masses that originate from different latitudes are approximately conserved. In Kalman products, the same anomalies and the acc ompanying air masses are diluted with their surroundings. The origin of the se differences is traced to the different space-time spectrum inherent to t he two synoptic products. In the spectrum of Kalman products, high zonal wa venumbers are exaggerated at low frequency relative to their counterparts i n FFSM. This pathological behavior appears to result through aliasing from diurnal variability that is undersampled in the UARS observations. We discu ss the relevance of these findings to subsequent analyses and to estimating momentum sources in the middle atmosphere.