Observational Characteristics of Atmospheric Anomalies with Short Meridional and Long Zonal Scales

Abstract

Puzzling short-meridional-scale perturbations of the lower stratospheric temperature field have recently been observed by Stanford and Short in analyses of satellite microwave radiance data. In this paper, we present corroborating evidence from rawinsonde, National Meteorological Center and European Centre for Medium Range Weather Forecasting analyses which confirm that the satellite-observed anomalies are atmospheric in origin, rather than some peculiarity in the data-gathering system. While data filtering is conveniently used for display purpose, it is shown that the anomalies unambiguously exist in unaltered data of several types. We also present results from further investigations utilizing a number of satellite microwave and infrared channels which more completely specify the character of this unusual phenomenon. In particular, it is shown that the temperature anomalies 1) clearly exist daily over large geographical regions in both summer hemisphere 2) exhibit a 180° phase change in the perturbation temperature structure between the upper troposphere and lower stratosphere and 3) are not apparent in the middle and upper stratosphere. In addition, the anomalies exhibit considerable scale anisotropy: over 45?50°N latitudes, individual anomaly peaks can be continuously traced over zonal dimensions of 5000?10 000 km, whereas their meridional scale is 1000?2000 km.